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Cefpodoxime proxetil is commonly used to treat cetacean patients with suspected or confirmed bacterial infections; however, pharmacokinetic data are needed to guide proper dosing in these species. Cefpodoxime proxetil is a time-dependent, semisynthetic, third-generation cephalosporin, appropriate for once-daily dosing and U.S. Food and Drug Administration-approved for use in dogs with a broad spectrum of activity including gram-positive and gram-negative species. The objective of this study was to evaluate the population pharmacokinetics of cefpodoxime in bottlenose dolphins ( Tursiops truncatus ). A sparse-sampling design was used, with serum from dolphins receiving cefpodoxime proxetil at 10 mg/kg orally every 24 h to treat suspected or confirmed bacterial infections. Serum samples ( n = 57) from 24 dolphins were analyzed at 12 time points from 0 to 96 h postdose. Serum samples were analyzed using liquid chromatography-mass spectrometry. Population pharmacokinetic analysis was performed using nonlinear mixed-effects modeling. One- and two-compartment linear models with first order absorption were tested. Covariates including weight, age, and sex were considered for inclusion in the model, and between-subject variability was incorporated. A two-compartment model performed best, where following an oral dose of 10 mg/kg, serum concentration reached a mean maximum concentration of 23.0 µg/ml, mean time to maximum concentration of 5.0 h, and mean half-life of 11.4 h. With daily dosing, accumulation was approximately 18% and steady state was reached by the second dose. Serum protein binding was 82.8% as determined by equilibrium dialysis, similar to plasma protein binding reported in dogs. Based on the population pharmacokinetic model, once-daily oral dosing was systemically absorbed and quickly reached maximum concentrations. The half-life in dolphins appears to be longer than other species studied to date. Given the paucity of antimicrobial pharmacokinetic studies in dolphins, and limited once-daily oral antibiotic options for this species, these data are helpful for clinicians to make informed antimicrobial choices.

Disposition of ceftizoxime was studied in Indian crossbred cows following a single IV dosing in field conditions. Six healthy lactating and six mastitic crossbred cows were assigned to two groups (Group 1 and Group 2). A single IV administration of ceftizoxime at the dose rate of 20mg/kg was administered to cows in both groups. Peak concentrations were recorded at 5min, decreasing sharply until 1h with plasma concentrations of 46.38±0.30μg/mL; concentrations were below detection limits at 24h. Ceftizoxime achieved peak concentrations at 96h and persisted up to 120h at a concentration of 36.71±0.96μg/mL in the milk of mastitic Indian crossbred cows. Staphylococcal colony count in acute mastitis was 52.33±4.98×10 5 colony forming units/mL milk and no growth was detected at 96h post-dosing, indicating that ceftizoxime following single IV administration at 20mg/kg may be effective to treat acute staphylococcal mastitis., (Copyright © 2018. Published by Elsevier Ltd.)

One of the relatively advance 3rd generation cephalosporins, cefpodoxime proxetil, is being used all-around. Generally, these are used for the cure of infections allied to urinary and respiratory tract. These cephalosporins have showed a remarkable in vitro activity against many strains of bacteria which are resistant to other orally used active medicinal substances. It is the first oral 3rd generation cephalosporin to be used in the cure of skin infections. The practice of H2 receptor antagonists, concerning lots of treatments recommended in patients with different types of ulcers and allergic urticarial condition, is raising hazards of unwanted secondary outcomes and drug interactions. Learning of in-vitro interaction between cefpodoxime poxetil and H2 blockers (Ranitidine, Famotidine and Cimetidine) were examined applying UV/Visible spectrophotometry and Infrared spectrometry. In the existence of H2 receptor blockers, the cefpodoxime proxetil availability was found to be decreased in vitro only under specific conditions. Furthermore, complexes of Cefpodoxime proxetil-H2 receptor antagonists were manufactured approving the interaction of these drugs. Finally, the above mentioned spectrophotometric techniques were employed to examine the complexes formed (Cefpodoxime proxetil-cimetidine, cefpodoxime proxetil-famotidine and cefpodoxime proxetil-ranitidine).

The renal excretion of creatinine and most drugs are the net result of glomerular filtration and tubular secretion, and their tubular secretions are mediated by individual transporters. Thus, we hypothesized that the increase of serum creatinine (SCr) levels attributing to inhibiting tubular transporters but not glomerular filtration rate (GFR) could be used to evaluate the tubular excretion of drugs mediated by identical or partial overlap transporter with creatinine. In this work, we firstly developed the creatinine excretion inhibition model with normal GFR by competitively inhibiting tubular transporters, and investigated the renal excretion of metformin, ceftizoxime and ofloxacin in vivo and in vitro. The results showed that the 24-hour urinary excretion of metformin and ceftizoxime in model rats were decreased by 25% and 17% compared to that in control rats, respectively. The uptake amount and urinary excretion of metformin and ceftizoxime could be inhibited by creatinine in renal cortical slices and isolated kidney perfusion. However, the urinary excretion of ofloxacin was not affected by high SCr. These results showed that the inhibition of tubular creatinine transporters by high SCr resulted to the decrease of urinary excretion of metformin and ceftizoxime, but not ofloxacin, which implied that the increase of SCr could also be used to evaluate the tubular excretion of drugs mediated by identical or partial overlap transporter with creatinine in normal GFR rats., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Cefpodoxime proxetil is a third generation cephalosporin antibiotic demonstrates pH dependent solubility and is highly soluble only in acidic pH. The purpose of this investigation was to design and develop immediate release tablets of cefpodoxime proxetil by direct compression method and determine the effect of different solid buffers (organic acids) such as fumaric acid (formulations F1-F4), maleic acid (formulations M1-M4) and citric acid (formulations C1-C4) by using cefpodoxime and acid in the ratios of 4:1, 2:1, 1:1 and 1:2 to achieve pH-independent release of the drug. Physical parameters and assay were found to be within the acceptable range as prescribed in USP 36 / NF 31. In vitro dissolution studies of each formulation were performed in distilled water, USP dissolution medium, HCl buffer solution of pH 1.2, phosphate buffer solutions of pH 4.5 and 6.8 to observe the drug release. The formulations F3, F4, M4 were selected for film coating on the basis of better drug release profile, to protect the drug from chemical degradation through hydrolysis. Film coated formulation F3, F4 and M4 showed a remarkable in vitro release of the drug (72.88±0.43 to 92.67±0.71%) within 30min of observation in all dissolution media and further evaluated by model independent and model dependent approaches. The drug release was found to be best fit to Weibull model as highest r 2 adjusted (0.924-0.998) and lowest AIC (18.416-54.710) values were obtained in all dissolution media. R Gui® applied for stability studies of F3 and F4 formulations, showing shelf lives of 28 & 27months at ambient and 33 months at accelerated temperatures. Formulation F4 was chosen as best formulation on the basis of physical properties, highest dissolution rate and stability studies.

The aim of this study is to develop a simple and applicable HPLC method for the detection of cefpodoxime acid (CFA) in rabbit plasma after oral administration of cefpodoxime proxetil (CFP) loaded chitosan-alginate (CH-ALG) beads formulation. CFP is a prodrug that is deesterified in vivo to its active metabolite CFA to exhibit antibiotic activity. Chromatographic separation of CFA and internal standard (IS) was achieved by a RP18(C18), Phenomenax®100, (250×4.6mm) with the mobile phase consisting of (0.02mol/l (20mM) ammonium acetate solution and acetonitrile (92:8, v/v, pH=4.6) at a flow rate of 1.0ml/min. The method was validated according to the requirements of US-FDA guidelines for bioanalytical method validation. The linear regression analysis for the calibration plots showed good linear relationship (R 2 =0.9905) in the working concentration range of 0.5-50μg/ml. The limits of detection and quantification (S/N=3) were 0.069 and 0.136μg/ml. Plasma CFA levels were successfully determined in rabbit with satisfactory precision and accuracy. The analyte was found to be stable after a number of stability studies. The proposed HPLC method was successfully applied to pharmacokinetic study in rabbits for CFP loaded CH-ALG beads and marketed immediate release (IR) tablets. All pharmacokinetic parameters were assessed., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The objective of the study was to use Monte Carlo simulation to determine the optimal treatment dosing regimen of the cefetamet sodium for injection by analysing the pharmacokinetics (PK) parameters in healthy Chinese volunteers, and antibacterial activity in vitro was also examined. A three-cross Latin square single-dose PK study was designed. Twelve healthy volunteers were randomized to receive 500, 1000, and 2000 mg of cefetamet sodium for IV infusion over 30 minutes in three periods sequentially; and the washout time in between periods was 3 days. The drug concentrations in plasma were analysed by high-performance liquid chromatography, and the PK parameters were calculated using DAS2.0 PK software. The peak concentrations (Cmax) at 0.5 hours were 37.78±7.29, 76.18±12.81, and 149.32±29.94 mg/l, the areas under concentration-time curve (AUC0-t) were 69.75±14.44, 139.06±22.62, and 278.54±53.12 mg h/l, and the elimination half-life (t1/2) were 1.69±0.19, 1.69±0.27, and 1.81±0.23 hours for 500, 1000, and 2000 mg of cefetamet sodium for injection, respectively. The disposition of cefetamet was appear to fit a two-compartment model with linear kinetics. Antibacterial activity in vitro showed that most Gram-negative bacteria, including non-extended-spectrum beta-lactamases (ESBL)-producing Enterobacter, Haemophilus influenzae, Moraxella catarrhalis, and Neisseria gonorrhoeae, were sensitive to cefetamet. The result of Monte Carlo simulation showed that the probability of target attainment for bactericidal response (%fT>MIC≧50%) for susceptible bacteria was reached at all three dosing regimens of 500 mg, q6h, 1000 and 2000 mg, q8h and q6h. Considering the efficacy, safety, and pharmacoeconomy comprehensively, we recommended the dosing regimen of 500 mg, q6h for further clinical treatment based on the principle of minimum daily dosage.

Ceftizoxime sodium is a third-generation cephalosporin available for parenteral administration, which is mainly excreted through urine. A rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) method was developed and validated for the determination of ceftizoxime in human serum and urine. The samples were purified by protein precipitation and separated on an XTerra Phenyl column (4.6 × 50 mm, 5 µm). Electrospray ionization in the positive ion mode and multiple reaction monitoring were used to monitor the ion transitions at m/z 383.9/227.0. The results revealed that the method had excellent selectivity. The linear range covered from 2.50 to 10,000 ng/mL in serum and from 0.500 to 50.0 µg/mL in urine, respectively. Intra-batch and inter-batch precisions (in terms of relative standard deviation) were all <15% and the accuracies (in terms of relative error) were within the range of ± 15%. The lower limit of quantification, stability and extraction recovery were also validated and satisfied the criteria of validation. Finally, the method was successfully applied to a pharmacokinetic study of Chinese elderly healthy subjects after intravenous administration. The Cmax values in serum were 34,721.3 ± 5,697.3 ng/mL. Serum concentrations declined with t1/2 of 2.57 ± 0.22 h., (© The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The pharmacokinetic (PK) and pharmacodynamic (PD) properties of intravenously (IV) administered cefetamet-Na and per os (PO) administered cefetamet pivoxil were investigated in eighteen healthy dogs at three different dose levels. The three doses for IV cefetamet-Na were 95, 190 and 380 mg, while those for oral cefetamet pivoxil were 125, 250 and 500 mg (both equivalent to 90, 180 and 360 mg of cefetamet). An efficacy predictor, measured as the ratios of the time that the concentration of the free drug is over the MIC90 (T > MIC90) and the dosing interval (f% T > MIC90) of IV and PO administration were calculated. The PK parameters' maximum concentration (C max), half-life (t 1/2) and area under the curve (AUC0-t ) after three IV doses were 42.85 ± 11.79 μg/mL, 1.66 ± 0.36 h and 80.10 ± 28.92 mg h/L (95 mg); 93.50 ± 30.51 μg/mL, 1.47 ± 0.13 h and 1.47 ± 0.13 mg h/L (190 mg); 185.74 ± 113.83 μg/mL, 1.60 ± 0.38 h and 263.20 ± 73.27 mg h/L (380 mg). After PO administration, the C max, t 1/2 and AUC0-t at three doses were 9.25 ± 1.02 μg/mL, 1.79 ± 0.50 h and 31.90 ± 4.76 mg h/L (125 mg); 9.75 ± 1.77 μg/mL, 1.93 ± 0.65 h and 42.69 ± 8.93 mg h/L (250 mg); 15.55 ± 6.65 μg/mL, 2.02 ± 0.54 h, and 68.72 ± 24.11 mg h/L (500 mg). The IV f% T > MIC90 was greater than PO f% T > MIC90 when MIC90 was within the range of 0.25-256 mg/L.

Osteomyelitis is a progressive destruction of bones caused by microorganisms. Inadequate or absent treatment increases the risk of bone growth inhibition, fractures, and sepsis. Among the diagnostic techniques, functional images are the most sensitive in detecting osteomyelitis in its early stages. However, these techniques do not have adequate specificity. By contrast, radiolabeled antibiotics could improve selectivity, since they are specifically recognized by the bacteria. The incorporation of these radiopharmaceuticals in drug-delivery systems with high affinity for bones could improve the overall uptake. In this work, long-circulating and alendronate-coated liposomes containing (99m)technetium-radiolabeled ceftizoxime were prepared and their ability to identify infectious foci (osteomyelitis) in animal models was evaluated. The effect of the presence of PEGylated lipids and surface-attached alendronate was evaluated. The bone-targeted long-circulating liposomal (99m)technetium-ceftizoxime showed higher uptake in regions of septic inflammation than did the non-long-circulating and/or alendronate-non-coated liposomes, showing that both the presence of PEGylated lipids and alendronate coating are important to optimize the bone targeting. Scintigraphic images of septic or aseptic inflammation-bearing Wistar rats, as well as healthy rats, were acquired at different time intervals after the intravenous administration of these liposomes. The target-to-non-target ratio proved to be significantly higher in the osteomyelitis-bearing animals for all investigated time intervals. Biodistribution studies were also performed after the intravenous administration of the formulation in osteomyelitis-bearing animals. A significant amount of liposomes were taken up by the organs of the mononuclear phagocyte system (liver and spleen). Intense renal excretion was also observed during the entire experiment period. Moreover, the liposome uptake by the infectious focus was significantly high. These results show that long-circulating and alendronate-coated liposomes containing (99m)technetium-radiolabeled ceftizoxime have a tropism for infectious foci.

Objective: To investigate the safety and maximum tolerable dosage of injectable cefetamet sodium Sixty healthy volunteers were enrolled in this study. with a single infusion in Chinese healthy volunteers., Methods: A double-blinded, randomized, placebo-controlled design was adopted. Eight dosages ranging from 100 mg to 5 000 mg were tested. The pharmacokinetics of the drug was analyzed using a Latin square three-cross self-controlled design, with 12 healthy volunteers receiving 500 mg, 1 000 mg and 2 000 mg of injectable cefetamet sodium in a randomized sequence. Blood and urine samples were collected and analyzed using high performance liquid chromatography with UV detection. The main pharmacokinetics parameters were calculated with DAS2.0 software., Results: 59 healthy volunteers completed the tolerance tests. Clinical adverse reactions occurred in 22.73% of participants in the test group and 6.67% of participants in the placebo group; but the difference was not statistically significant. Common adverse events included infusion pain and dizziness. Rare adverse events such as palpitations, diarrhea and rash occurred in participants in the test group. All of the adverse reactions were mild. Abnormal laboratory test results occurred in 43.18% participants in the test group and 53.33% participants in the placebo group; again the difference was not statistically significant. Common abnormal laboratory test results included abnormal bowel flora, stool abnormalities, abnormal urine and elevated serum potassium. After a single infusion of 500 mg, 1 000 mg and 2 000 mg of injectable cefetamet sodium, peak concentration of the drug at 0.5 h reached (37.92 +/- 7.43), (74.90 +/- 10.67) and (148.54 +/- 31.63) mg/L, with areas under concentration-time curve of (72.08 +/- 14.98), (144.28 +/- 24.57) and (286.66 +/- 54.25) (mg x h)/L, respectively. Their elimination half-life was (2.03 +/- 0.38), (2.04 +/- 0.26), and (2.12 +/- 0.26) h, respectively. The disposition of cefetamet was presented as a two-compartment model with linear kinetics. The 24-hour urinary accumulation excretion was 76.6%-67.5%., Conclusion: The maximum single tolerated dose of injectable cefetamet sodium is 5 000 mg. The pharmacokinetics is a two-compartment model with linear kinetics within a dose range 500-2 000 mg.

Cefpodoxime proxetil (CFP), a broad-spectrum third-generation cephalosporin, has been used most widely in the treatment of respiratory and urinary tract infections. For bioequivalence study of CFP in rabbit plasma, it was necessary to develop a highly sensitive and selective high-performance liquid chromatographic (HPLC) method with fluorescence (FL) detection. The pre-column labeling of cefpodoxime acid (CFA) (active metabolite) with an efficient benzofurazan type fluorogenic reagent, 4-N,N-dimethyl aminosulfonyl-7-fluoro-2,1,3-benzoxadiazole (DBD-F) was carried out in the present study in 100mM borate buffer (pH=8.5) at 50°C for 15min. The obtained fluorescent products were separated on C18 column with an isocratic elution of the mobile phase, which consists of 10mM phosphate buffer (pH=3.5)/CH3CN (70:30, v/v). The fluorescent product (DBD-CFA) was detected fluorimetrically at 556nm with an excitation wavelength of 430nm. Cefotaxime sodium was used as internal standard. The method was validated according to the requirements of US-FDA guidelines. The correlation coefficient of 0.999 was obtained in the concentration ranges of 10-1000ngmL(-1). The limits of detection and quantification (S/N=3) were 3 and 10ngmL(-1), respectively. Plasma CFA levels were successfully determined in rabbit with satisfactory precision and accuracy. The proposed HPLC-FL method was successfully applied to study bioequivalence in rabbits for two formulations of different brands contained CFP (prodrug) in a randomized, two-way, single-dose, crossover study and all pharmacokinetic parameters for the two formulations were assessed., (Copyright © 2013 Elsevier B.V. All rights reserved.)

A sensitive HPLC method was developed for the determination of cefpodoxime in human plasma. After protein precipitation with acetonitrile, sample was injected into the HPLC system for analysis. The chromatographic separation was carried out on a Diamonsil C18 column with a mobile phase consisting of acetonitrile-water. The mobile phase composed of water (containing 20 mmol/L monoammonium phosphate) and acetonitrile (90: 10, v/v). The detection wavelength was set at 254 nm. The standard curve for cefpodoxime was linear over the concentration range of 0.05-8 μg/mL with a lower limit of quantification of 0.05 μg/mL. The intra- and inter-day RSD values were lower than 10%, and the RE values were within±5%. For the pharmacokinetic analysis of plasma, the mean (SD) values obtained for the formulation were: Cmax, 4.21 (0.62) µg/mL; Tmax, 2.47 (0.61) h; t1/2, 2.38 (0.46) h; AUC0-24 h, 21.13 (3.39) µg/mL/h; and AUC0-∞, 23.34 (3.87) µg/mL/h; MRT, 2.21 (0.41) h, respectively., (© Georg Thieme Verlag KG Stuttgart · New York.)

A sensitive and selective electrochemical method for Cefpodoxime Proxetil (CP) determination has been developed by incorporating gold nanoparticles (AuNPs) onto the poly-1,5-diaminonapthalene layer (p-DAN) coated pyrolytic graphite. The modified sensor was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The sensor exhibited an effective catalytic response towards oxidation of CP with excellent reproducibility and stability. The peak current of CP was found to be linear in the range of 0.1-12 μM and detection limit and sensitivity of 39 nM (S/N=3) and 4.621 μA μM(-1), respectively, were observed. The method was successfully applied for the determination of CP in pharmaceutical formulations and human urine samples. The common metabolites present in human urine such as uric acid, ascorbic acid, xanthine and hypoxanthine did not interfere in the determination. A comparison of the results obtained by using developed method with high performance liquid chromatography (HPLC) indicated a good agreement. The method is simple, sensitive, rapid and precise and is useful for the routine determination of CP in pharmaceutical dosages and biological samples., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Osteomyelitis is an infectious disease located in the bone or bone marrow. Long-circulating and pH-sensitive liposomes containing a technetium-99m-labeled antibiotic, ceftizoxime, (SpHL-(99m)Tc-CF) were developed to identify osteomyelitis foci. Biodistribution studies and scintigraphic images of bone infection or non infection-bearing rats that had been treated with these liposomes were performed. A high accumulation in infectious foci and high values in the target-non target ratio could be observed. These results indicate the potential of SpHL-(99m)Tc-CF as a potential agent for the diagnosis of bone infections., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

This study aims to prove the complexation of cefpodoxime proxetil (CP) by hydroxypropyl-β-cyclodextrin (HP-β-CD) in the presence of sodium carboxymethyl cellulose (Na CMC), and makes a comparison of commercial tablets by dissolution and antimicrobial activity studies. The CP--HP-β-CD complex was prepared by kneading method and characterized by SEM, FTIR and DSC. The solubility method was used to investigate the effect of HP-β-CD and Na CMC on the solubility of CP. The complex tablets were prepared using direct compression method. Dissolution studies were performed with complex tablets and commercial tablets in pH 1.2, 4.5, 6.8 and 7.4 buffer solutions. It was observed that complexation occurred in all formulations, and HP-β-CD is able to increase CP solubility and dissolution rate of CP was improved from complex tablets, when compared with commercial tablets. Furthermore, the antimicrobial activity studies revealed that the CP--HP-β-CD complex and complex tablets were shown to have more effective antimicrobial activity than commercial tablets. It is evident from the results that complexation with HP-β-CD in the presence of Na CMC is feasible way to prepare a more efficient tablet formulation with improved dissolution and antimicrobial activity.

Cefetamet is a potent antibiotic to treat respiratory and urinary tract infections. To improve oral bioavailability, it is administered as a prodrug, cefetamet pivoxyl hydrolyzed by esterase following absorption. A quantification method using a mass spectrometry was developed for the determination of cefetamet in human plasma. After a protein precipitation with acetonitrile, the analytes were chromatographed on a reversed-phase C₁₈ column and detected by a tandem mass spectrometer with electrospray ionization. The accuracy and precision of the assay were in accordance with FDA regulations for the validation of bioanalytical methods. This method was used to measure the concentrations of the cefetamet in plasma after a single oral administration of 500 mg cefetamet pivoxyl., (Copyright © 2010 John Wiley & Sons, Ltd.)

Pharmacokinetics of cefpodoxime in plasma (total concentration) and subcutaneous fluid (free concentration using microdialysis) was investigated in dogs following single oral administration of prodrug cefpodoxime proxetil (equivalent to 5 and 10 mg/kg of cefpodoxime). In a cross over study design, six dogs per dose were utilized after a 1 week washout period. Plasma, microdialysate, and urine samples were collected upto 24 h and analyzed using high performance liquid chromatography. The average maximum concentration (C(max) ) of cefpodoxime in plasma was 13.66 (±6.30) and 27.14 (±4.56) μg/mL with elimination half-life (t(1/2) ) of 3.01 (±0.49) and 4.72 (±1.46) h following 5 and 10 mg/kg dose, respectively. The respective average area under the curve (AUC(0-∞) ) was 82.94 (±30.17) and 107.71 (±30.79) μg·h/mL. Cefpodoxime was readily distributed to skin and average free C(max) in subcutaneous fluid was 1.70 (±0.55) and 3.06 (±0.93) μg/mL at the two doses. Urinary excretion (unchanged cefpodoxime) was the major elimination route. Comparison of subcutaneous fluid concentrations using pharmacokinetic/pharmacodynamic indices of fT(>MIC) indicated that at 10 mg/kg dose; cefpodoxime would yield good therapeutic outcome in skin infections for bacteria with MIC(50) upto 0.5 μg/mL while higher doses (or more frequent dosing) may be needed for bacteria with higher MICs. High urine concentrations suggested cefpodoxime use for urinary infections in dogs., (© 2010 Blackwell Publishing Ltd.)

Background: Cefpodoxime is a semisynthetic third generation cephalosporin analogue with a relatively broader spectrum of antimicrobial activity against gram negative and gram positive organisms. This is attributed to their somewhat increased resistance to degradation by the betalactamase. Cefpodoxime shows good activity against Klebsiella pneumonia, many members of enterobactericeae and almost all strains of Escherichia coli. It is extensively used in human beings against infections caused by susceptible organisms for a prolonged period and even without its judicious indication. Though various researchers have worked on the pharmacokinetic aspects of the drug, its effects on biochemical parameters and spermatozoa activity are scarcely available in literature., Aim: To determine the oral kinetic ( blood and tissue) after single therapeutic dose of cefpodoxime proxetil (20mg/kg oral bid 7 days) in rats of either sex on tissue half life and certain biochemical parameters such as glucose, hemoglobin, protein, ALT, AST and other parameters like tissue residue, sperm count and spermatozoa motility in male rats., Materials and Methods: For kinetic studies,24 Wister rats of either sex, 3 months of age, (180-210 gm) were used.(Group I-IV; n=6) Blood samples collected from each animal of Group IV through heart puncture at 0 hour to serve as predrug control. All the group (I-IV) received cefpodoxime proxetil 20 mg/kg once orally as a single dose. At the end of 1,4,12 and 24 hour post oral administration, GroupI,II,III and IVwere utilized for kinetic studies. Blood samples were collected from each animal and vital organs viz brain, lung, liver, spleen, kidney and heart were dissected out for drug analysis and determination of weight. For biochemical parameters, tissue residue and spermatozoa motility, twelve male rats were randomly divided into Groups A and B (n=6) Group B received cefpodoxime (20mg/kg orally bid 7 days) while Group A served as control. Biochemical parameters [Blood glucose, protein, Aspartate transaminase(AST), Alanine transaminase(ALT)and hemoglobin] were measured at 0 and 7 th day while sperm count (total,live and dead)and mean organ weight (study and control group) and tissue residue of drug were evaluated at the end of treatment. Absorption of cefpodoxime was observed at 2 hour and reached a maximum at 4 hour and persisted in blood till 24 hour. Elimination half life in lung was highest followed by heart, liver, kidney and spleen while t½ k in plasma was very low suggesting more affinity of cefpodoxime for tissues than blood., Results and Conclusion: Blood glucose, protein, AST and ALT activities were not significantly altered but the hemoglobin level and total and live sperm count decreased significantly in the study group compared to the control group. Residual level of cefpodoxime was highest in liver followed by kidney and other study organs. Therefore, the drug should be used in human beings judiciously and further study on human subjects is warranted.

Objective: To determine the effect of protein binding on the pharmacokinetics and distribution from plasma to interstitial fluid (ISF) of cephalexin and cefpodoxime proxetil in dogs., Animals: 6 healthy dogs., Procedures: In a crossover study design, 25 mg of cephalexin/kg or 9.6 mg of cefpodoxime/kg was administered orally. Blood samples were collected before (time 0) and 0.33, 0.66, 1, 2, 3, 4, 6, 8, 10, 12, 16, and 24 hours after treatment. An ultrafiltration device was used in vivo to collect ISF at 0, 2, 4, 6, 8, 10, 12, 16, and 24 hours. Plasma and ISF concentrations were analyzed with high-pressure liquid chromatography. Plasma protein binding was measured by use of a microcentrifugation technique., Results: Mean plasma protein binding for cefpodoxime and cephalexin was 82.6% and 20.8%, respectively. Mean ± SD values for cephalexin in plasma were determined for peak plasma concentration (Cmax, 31.5±11.5 μg/mL), area under the time-concentration curve (AUC, 155.6±29.5 μg•h/mL), and terminal half-life (T½, 4.7±1.2 hours); corresponding values in ISF were 16.3±5.8 μg/mL, 878±21.0 μg•h/mL, and 3.2±0.6 hours, respectively. Mean±SD values for cefpodoxime in plasma were 33.0±6.9 μg/mL (Cmax), 282.8±44.0 μg•h/mL (AUC), and 5.7±0.9 hours (T1/2); corresponding values in ISF were 4.3±2.0 μg/mL, 575±174 μg•h/mL, and 10.4±3.3 hours, respectively., Conclusions and Clinical Relevance: Tissue concentration of protein-unbound cefpodoxime was similar to that of the protein-unbound plasma concentration. Cefpodoxime remained in tissues longer than did cephalexin.

Poorly water-soluble drugs such as cefpodoxime proxetil (400 μg/ml) offer a challenging problem in drug formulation as poor solubility is generally associated with poor dissolution characteristics and thus poor oral bioavailability. According to these characteristics, preparation of cefpodoxime proxetil microparticle has been achieved using high-speed homogenization. Polymers (methylcellulose, sodium alginate, and chitosan) were precipitated on the surface of cefpodoxime proxetil using sodium citrate and calcium chloride as salting-out agents. The pure drug and the prepared microparticles with different concentrations of polymer (0.05-1.0%) were characterized in terms of solubility, drug content, particle size, thermal behavior (differential scanning calorimeter), surface morphology (scanning electron microscopy), in vitro drug release, and stability studies. The in vivo performance was assessed by pharmacokinetic study. The dissolution studies demonstrate a marked increase in the dissolution rate in comparison with pure drug. The considerable improvement in the dissolution rate of cefpodoxime proxetil from optimized microparticle was attributed to the wetting effect of polymers, altered surface morphology, and micronization of drug particles. The optimized microparticles exhibited excellent stability on storage at accelerated condition. The in vivo studies revealed that the optimized formulations provided improved pharmacokinetic parameter in rats as compared with pure drug. The particle size of drug was drastically reduced during formulation process of microparticles.

Cefpodoxime proxetil (CP) is a prodrug, the third generation cephem-type broad-spectrum antibiotic administered orally. However, CP was found to be a poorly water-soluble drug with low bioavailability when orally administered. In the present investigation, the spray-dried cefpodoxime proxetil nanosuspension (SDN) was prepared. The physicochemical properties were characterized by rheological evaluation, particle size measurement and its distribution, dynamics of reconstitution, in-vitro dissolution testing, surface morphology, surface area and pore size measurements. The pharmacokinetic study of SDN, in comparison to a marketed cefpodoxime proxetil for oral suspension (MS), was also performed in rabbits after a single oral dose. It was found that SDN exhibited a significant decrease in t(max), a 1.60-fold higher area under curve (AUC) and 2.33-fold higher maximum plasma concentration (C(max)) than MS.

Cefpodoxime proxetil (CP) is a prodrug with poor oral bioavailability because of its metabolism to Cefpodoxime acid (CA) in luminal contents and intestinal epithelial cells. In the present investigation, regional variability in different segments of the gastrointestinal tract vis-à-vis solubility and metabolism were investigated, and the results indicated potential for a gastro retentive (GR) dosage form. Suitability of a GR dosage from for CP and finally in vivo efficacy were investigated. Thereafter, an effervescent floating GR dosage form was developed for CP and evaluated in rats. The GR dosage form improved the oral bioavailability of CP significantly by about 75%, hence providing a proof-of-concept. The Tmax value increased to 1.43+/-0.24 h from 0.91+/-0.23 h of pure drug, while Cmax values of 4735+/-802 ng/ml and 3094+/-567 ng/ml were obtained for the GR dosage form and pure drug respectively.

The pharmacokinetic properties of cefpodoxime, and its prodrug, cefpodoxime proxetil, were evaluated in two separate studies, one following intravenous (i.v.) administration of cefpodoxime sodium and the second after oral (p.o.) administration of cefpodoxime proxetil to healthy dogs. After cefpodoxime administration, serial blood samples were collected and plasma concentrations were determined by high performance liquid chromatography (HPLC). A single i.v. administration of cefpodoxime sodium at a dose of 10 mg cefpodoxime/kg body weight resulted in a cefpodoxime average maximum plasma concentration (Cmax) of 91 (+/-17.7) microg/mL, measured at 0.5 h after drug administration, an average half-life (t1/2) of 4.67 (+/-0.680) h, an average AUC(0-infinity) of 454 (+/-83.1) h.microg/mL, an average V(d(ss)) of 151 (+/-27) mL/kg, an average Cl(B) of 22.7 (+/-4.2) mL/h/kg and an average MRT(0-infinity) of 5.97 (+/-0.573) h. When dose normalized to 10 mg cefpodoxime/kg body weight, cefpodoxime proxetil administered orally resulted in Cmax of 17.8 +/- 11.4 microg/mL for the tablet formulation and 20.1 +/- 6.20 microg/mL for the suspension formulation and an average AUC(0-LOQ) of 156 (+/-76.1) h.microg/mL for the tablet formulation and 162 (+/-48.6) h.microg/mL for the suspension formulation. Relative bioavailability of the two oral formulations was 1.04 (suspension compared with tablet), whereas the absolute bioavailability of both oral formulations was estimated to be approximately 35-36% in the cross-study comparison with the i.v. pharmacokinetics. Combined with previous studies, these results suggest that a single daily oral dose of 5-10 mg cefpodoxime/kg body weight as cefpodoxime proxetil maintains plasma concentrations effective for treatment of specified skin infections in dogs.

The purpose of the present study was to investigate the role of multidrug resistance-associated protein 4 (MRP4) in the tubular secretion of cephalosporin antibiotics. Most of the injectable cephalosporins have an inhibitory effect on the ATP-dependent uptake of [(3)H]dehydroepiandrosterone sulfate by membrane vesicles expressing hMRP4, whereas cephaloridine, cefsulodin, and cefepime do not. Aminocephalosporins have a weak inhibitory effect. Significant ATP-dependent transport of ceftizoxime (K(m), 18 microM), cefazolin (K(m), 80 microM), cefotaxime, and cefmetazole has been observed only in the membrane vesicles expressing hMRP4. Ceftizoxime and cefazolin were given by a constant intravenous infusion to wild-type and Mrp4(-/-) mice. The steady-state plasma concentrations of ceftizoxime and cefazolin were unchanged in Mrp4(-)(/)(-) mice. The urinary recovery of ceftizoxime was significantly reduced in Mrp4(-/-) mice, whereas it was unchanged for cefazolin. The kidney-to-plasma concentration ratio of ceftizoxime and cefazolin was increased 2.0- and 2.7-fold in Mrp4(-/-) mice, respectively; thus, the renal clearance with regard to the kidney concentration was reduced in Mrp4(-/-) mice, to 7.5 and 34% of the corresponding control values, respectively. These results suggest that Mrp4 is involved in the tubular secretion of ceftizoxime and cefazolin, in concert with basolateral uptake transporters.

Cefpodoxime proxetil (CP) is a prodrug of cefpodoxime acid (CA), and is supplied as racemic mixture of R- and S-enantiomers. CP has only 50% absolute bioavailability, and the reasons responsible for low bioavailability remain poorly understood. The present work ascertains physicochemical and biological properties of individual isomers of CP and explores their capacity to optimize delivery of CP. Both isomers showed similar pH stability behavior, but R-isomer was more susceptible to enzymatic metabolism compared to S-isomer, when incubated with enzymes collected from various segments of GIT. Based on the in vitro and in vivo results, use of S-isomer for development of a dosage form such as gastro-retentive dosage form can improve oral bioavailability of CP.

Learning about the behavior of a drug in biological environment enables application of better formulation strategies to improve bioavailability of the same. Cefpodoxime proxetil (CP) is a prodrug, which is orally administered cephalosporin with only 50% absolute bioavailability. Despite previous studies, reasons responsible for low bioavailability of CP remain poorly understood. The present study tries to ascertain reasons for the low oral bioavailability of CP. The in vitro, in situ and ex vivo studies showed interesting results, where metabolism of CP into cefpodoxime acid (CA) inside the intestinal epithelial cell and preferential efflux of CA into lumen was identified as primary reason for low oral bioavailability of CP. Presence of specific carriers or transportation mechanism on the apical side membrane of enterocyte, than basal side of the same was observed.

The present work explains the development and validation of a simple and reliable isomer specific liquid chromatographic method for the quantitative determination of cefpodoxime proxetil (CP) in rat in situ intestinal perfusate samples. Chromatography was carried out by reversed-phase technique on a C-18 column with a mobile phase composed of 20 mM ammonium acetate buffer (pH 5.0) and acetonitrile in the ratio of 62:38 pumped at a flow-rate of 1 ml/min. The detection was carried out at 235 nm and a column temperature of 30 degrees C. The method was evaluated for the various validation parameters, such as linearity, accuracy, precision, LOD, LOQ, specificity, selectivity, and sample stability. The results of intra- and inter-day validation (n = 3) showed the method to be efficient and the same was applied in an in situ permeability study conducted for CP in rats.

Unlabelled: This study aimed to investigate the biodistribution of the 99mTc-ceftizoxime in normal rats and in rats bearing septic and sterile induced abscess., Material and Methods: Three groups of rats were studied. a) Six normal rats b) 15 rats with E. coli induced abscess and c) 15 rats with sterile zymosan induced abscess. Septic abscess was induced with 2 x 10(8) colony forming units of E. coli and sterile one with 0.1 mL of 5% sterile Zymosan. 24 h after the abscess induction, 12 MBq of 99mTc-CFT were injected iv. and whole body images were collected at 30 min, 1, 2, 4 and 6 h p.i. Areas of interest were drawn and lesion/background index was calculated. The 6 normal rats were scanned at the same times, killed at 6 h p.i and kidney, liver, spleen, lung, heart and muscle activity were measured. Each organ was weighed, cut and its activity measured. Parallelly, the biological activity of the labeled antibiotic and its binding to the E. coli and S. aureus bacteria were analyzed., Results: High biliary excretion was seen in all rats. Organ measurement showed the maximal uptake in kidney and very low uptake in muscles. Mean +/- s.d abscess/background ratio at 30 min, 1, 2, 4 and 6 h were 2.60 +/- 0.36, 2.67 +/- 0.66, 2.6 0 +/- 0.58, 2.78 +/- 0.84, 3.24 +/- 1.00 for septic abscess and 2.37 +/- 0.39, 2.10 +/- 0.38, 1.97 +/- 0.34, 1.82 +/- 0.25, 1.65 +/- 0.23 for aseptic abscess. The 99mTc-CFT uptake was significantly higher in the septic abscess than in sterile one (p < 0.05). The 99mTc-CFT uptake in the septic abscess remains stable or increases until along the 6 h. The 99mTc-CFT uptake in the aseptic abscess decreases along the time., Conclusions: The scintigraphy with 99mTc-CFT seems able to differentiate sterile inflammation from infection. High biliary excretion limits its application in abdomen. Main application could be diagnosis of osteoarticular infection.

Purpose: The aim of this study was to investigate the pharmacokinetics of cefpodoxime in interstitial tissue fluids (skeletal muscle and lung) in rats by microdialysis, and to examine the relationship between free drug levels in plasma and in tissues., Methods: Cefpodoxime was administered to anesthetized male Wistar rats as single intravenous bolus of 10 or 20 mg/kg and constant infusion of 260 microg/h with a loading dose. The protein binding of cefpodoxime in rat plasma was determined using ultrafiltration., Results: The average protein binding of cefpodoxime in rat plasma was 38%. The half-lives in plasma, muscle and lung were similar (approximately 5 h). After constant rate infusion, the free concentrations in the muscle and the lung were almost identical, but lower than total and free plasma concentrations. The data were modeled simultaneously using a two-compartmental body model., Conclusions: Free interstitial levels of cefpodoxime in muscle and lung tissue are very similar. Since muscle is more accessible than lung, free muscle concentrations may serve as a good surrogate for unbound concentrations in lung.

Aim of Study: To demonstrate that administration of fluids and the consequent improvement of fluid balance during a surgical procedure can modify the tissue diffusion of ceftizoxime., Methods: Twenty-eight patients (30-79 years) undergoing major abdominal surgery of the colon were administered ceftizoxime 30 mg/kg i.v. at induction of anesthesia. A sample of arterial blood was taken before administration of the drug (t0) and then again at the time of vascular occlusion of the colon segment to be removed (t1). A sample of the segment of removed colon was taken. The patients were divided into two groups on the basis of the fluid balance between t0 and t1: group A (n = 17) with a fluid balance <1,000 ml and group B (n = 11) with a fluid balance >1,000 ml. The parameters evaluated in each group were: weight, height and age of the patients, serum and tissue antibiotic concentration, percent ratio of serum and tissue concentration, time elapsed between t0 and t1, volume of administered fluids between t0 and t1, diuresis and hourly diuresis between t0 and t1 and body fluid distribution, obtained using a bioelectrical impedance analyzer. The mean results obtained in the two groups were then compared using Student's t test., Results: The balance of fluids calculated up to t1 was 675 +/- 308 ml for group A and 1,411 +/- 405 ml for group B (p < 0.01). The means of the recorded values that showed statistically significant differences were: mean percent concentration ratio (43.6 +/- 8.4 vs. 84 +/- 16%; p < 0.05), concentration in the colonic segment (16.3 +/- 7.9 vs. 37.2 +/- 25.9 mg/ml; p < 0.05), urinary volume gathered up to t1 (538 +/- 557 vs. 169 +/- 104 ml; p < 0.05), hourly urinary volume up to t1 (311.1 +/- 296 vs. 97.6 +/- 77.9 ml/h; p < 0.05), percent variation of resistance (95.1 +/- 5.1 vs. 89.7 +/- 8.6; p < 0.05). The other means did not show any significant statistical differences., Conclusions: A higher tissue water level seems to facilitate the penetration of the antibiotic into the tissue according to the pharmacokinetic characteristics of ceftizoxime: high amount of free drug (not bound to plasma proteins) and high hydrosolubility., (Copyright 2005 S. Karger AG, Basel)

Microdialysis is a technique that allows the measurement of free antibiotic concentrations in different tissues, which are responsible for the antibacterial activity at the infection site. In an open, randomized, 2-way crossover study in healthy volunteers, the muscle penetration of orally administered cefpodoxime (400 mg) and cefixime (400 mg) was compared using microdialysis. The results show that the total plasma concentration-time profiles of each antibiotic were similar; the area under the curve for cefpodoxime was 22.4 +/- 8.7 versus 25.6 +/- 8.5 mg/L*h for cefixime. However, tissue penetration was twice as high for cefpodoxime (area under the curve 15.4 +/- 5.1 mg/L*h) as for cefixime (area under the curve 7.3 mg/L*h). This degree of tissue distribution is consistent with their protein binding of 21% for cefpodoxime and 65% for cefixime. After equilibration, the unbound tissue concentrations of both antibiotics were similar to their unbound plasma concentrations. Pharmacokinetic modeling was applied to describe the pharmacokinetic profiles in plasma and muscle. The study demonstrates that cefpodoxime shows greater tissue penetration than cefixime.

The bacterial time-kill curves of cefpodoxime and cefixime against four bacterial strains (Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae/penicillin sensitive and S. pneumoniae/penicillin intermediate) were compared in in vitro infection models in which various human pharmacokinetic profiles of unbound antibiotic were simulated. This approach offers more detailed information than the minimum inhibitory concentration (MIC) does about the time course of antibacterial efficacy of an antibiotic. A pharmacokinetic-pharmacodynamic (PK-PD) model based on unbound antibiotic concentrations at the site of infection, and a sigmoid Emax-relationship with EC50 as the antibiotic concentration necessary to produce 50% of the maximum effect, effectively described the antimicrobial efficacy of both cefpodoxime and cefixime. The EC50 values of cefpodoxime and cefixime were consistent with their respective MIC values. Both antibiotics had similar high potency against H. influenzae (EC50: 0.04 mg/L) and M. catarrhalis (EC50: 0.12 mg/L), while the potency of cefpodoxime against S. pneumoniae strains was about 10-fold higher than that of cefixime (EC50s/sensitive strain: 0.02 mg/L versus 0.27 mg/L; EC50s/intermediate strain: 0.09 mg/L versus 0.69 mg/L). Applications of this model and unbound tissue PK profiles obtained from a previous clinical study performed in our group, showed that cefpodoxime has higher bacteriological potency than cefixime against S. pneumoniae. Simulations based on this model allow the comparison of antibacterial efficacy of different antibiotics and dosing regimens.

Objectives: To determine the disposition of orally administered cefpodoxime proxetil in foals and adult horses and measure the minimum inhibitory concentrations (MICs) of the drug against common bacterial pathogens of horses., Animals: 6 healthy adult horses and 6 healthy foals at 7 to 14 days of age and again at 3 to 4 months of age., Procedure: A single dose of cefpodoxime proxetil oral suspension was administered (10 mg/kg) to each horse by use of a nasogastric tube. In 7- to 14-day-old foals, 5 additional doses were administered intragastrically at 12-hour intervals. The MIC of cefpodoxime for each of 173 bacterial isolates was determined by use of a commercially available test., Results: In 7- to 14-day-old foals, mean +/- SD time to peak serum concentration (Tmax) was 1.7 +/- 0.7 hours, maximum serum concentration (Cmax) was 0.81 +/- 0.22 microg/mL, and elimination half-life (harmonic mean) was 7.2 hours. Disposition of cefpodoxime in 3- to 4-month-old foals was not significantly different from that of neonates. Adult horses had significantly higher Cmax and significantly lower Tmax, compared with values for foals. The MIC of cefpodoxime required to inhibit growth of 90% of isolates for Salmonella enterica, Escherichia coli, Pasteurella spp, Klebsiella spp, and beta-hemolytic streptococci was 0.38, 1.00, 0.16, 0.19, and 0.09 microg/mL, respectively., Conclusions and Clinical Relevance: Oral administration at a dosage of 10 mg/kg every 6 to 12 hours would appear appropriate for the treatment of equine neonates with bacterial infections.

Objective: To compare the pharmacokinetics/pharmacodynamics property of cefdinir, cefpodoxime proxetil and cefaclor against common bacteria of community acquired infections and evaluate the recommended regimens., Methods: The antibacterial activities of 3 agents against 238 clinical isolates were determined by standard agar dilution test and the pharmacokinetics of these antibiotics in male healthy volunteers were conducted in Latin-square manner. The time over MIC (T > MIC) of serum antibiotic concentrations were calculated with pharmacokinetic equation and MIC., Results: The value of MIC90 s cefdinir against these bacterial strains except penicillin non-sensitive pneumococci were 0.031-1 mg/L. Cefpodoxime held similar antibacterial activity with cefdinir, but was less potent against staphylococci. Cefaclor had much higher MIC values than other two drugs. After oral administration of 250 mg cefaclor, the drug concentration quickly reached peak concentration of 4.95 mg/L +/- 2.41 mg/L and the eliminative half time was 0.69 h +/- 0.6 h; the Tmax, Cmax and T1/2beta of cefdinir and cefpodoxime after oral administration of 100 mg were 2.5 h +/- 0.48 h, 0.81 mg/L +/- 0.19 mg/L, 1.73 h +/- 0.3 h and 2.38 h +/- 0.43 h, 1.12 mg/L +/- 0.28 mg/L, 1.92 h +/- 0.55 h, respectively. T > MIC of cefdinir in thrice daily administration were longer than 40% of medication interval against most of the tested isolates; no T > MIC period was found in cefpodoxime against staphylococci and the T > MICs of cefaclor after 250 mg oral administration were shorter than expected values against most bacteria., Conclusion: With powerful antibacterial activity, the T > MICs of cefdinir after 100 mg oral administration can meet with the clinical requirement in most infections; PK/PD value of cefpodoxime proxetil against staphylococci is lower than expectancy and 250 mg cefaclor 3 times daily is not enough to the treatment of common community acquired infections, the regimens of cefpodoxime proxetil and cefclor should be furtherly optimized.

Cefpodoxime is a oral third generation cephalosporin active against most of gram positive and gram negative bacteria except Pseudomonas, B. fragilis and Entrococcous. Clinical studies have confirmed efficacy of cefpodoxime in acute otitis media, sinusitis and tosillopharyngitis. Twice daily administration and safety profile increases compliance and decreases failure rate. It has a role as switch over therapy from intravenous ceftriaxone in serious respiratory tract infections (RTIs). In areas where common respiratory pathogens show decreased sensitivity to penicillins and macrolides cefpodoxime can be used as empirical first line therapy in respiratory tract infections. It seems to be a promising molecule in pediatric typhoid fever because of its excellent activity against Salmonella species but clinical trials are limited.

The influence of temperature and relative humidity on the stability of cefetamet pivoxil (CFP) and its hydrochloride (CFP.HCl) in solid phase was investigated. The process of degradation was studied using HPLC with UV detection. The degradation of CFP and CFP.HCl occurring at air humidity RH>50% is an autocatalytic first-order reaction with respect to substrate concentration, while at 0% relative humidity of the ambient air it is a first-order reaction relative to substrate concentration for CFP.HCl, and a reversible first-order reaction for CFP. The rate constants (k) were determined in dry air at 373 K, 378 K, 383 K, 388 K and 393 K; at air humidity RH = 76.4% at 333 K, .343 K, 353 K, 363 K and 373 K; and at 363 K at air humidity RH>50%. The kinetic and thermodynamic parameters of the degradation were calculated.

Absolute bioavailability of cefpodoxime proxetil is both limited by its low solubility in aqueous solution and its intraluminal hydrolysis. The oil-in-water submicron emulsion was proven to be effective in protecting the prodrug from the enzymatic attack in rabbit intestinal washings. The aim of the study was to perform a pharmacokinetic study in conscious rats to confirm o/w submicron superiority in comparison to other oral formulations (hydro-alcoholic solution, suspension and coarse emulsion). The pharmacokinetic study was performed in conscious rats implanted with permanent aortic catheters. A parenteral solution of cefpodoxime was injected via this catheter, and oral formulations were administered orally. The cefpodoxime plasma level was performed by a HPLC validated method. The pharmacokinetic parameters, t1/2, Cmax, tmax, AUC and absolute bioavailability (F) were determined with a non-compartmental analysis. The results show a significant increase of F for submicron emulsion (97.4%) between the other oral formulations. No significant difference of F was found between the other oral formulations, even with the coarse o/w emulsion. The o/w submicron emulsion made the enhancement of the absolute bioavailability of cefpodoxime proxetil possible. This benefit could be explained by the low droplet size of the submicron emulsion which improve the absorption process of the prodrug.

Cefpodoxime is a semi-synthetic, third generation cephalosporin. The drug is available for use as a prodrug-Cefpodoxime proxetil, which is absorbed readily from the gut. It reaches adequate levels exceeding the MIC in most of the body fluids. It is excreted by kidneys, unchanged. Dose needs adjustment in compromised renal function. The drug is active against common gram-positive cocci like staphylococci including penicillinase producing strains, streptococci and gram negative bacteria like Hemophilus, E. coli, Klebsiella, Moraxella, Meningococci, Gonococci etc. The drug is useful in common upper and lower respiratory tract infections, sinusitis, and otitis media. The drug is also used in skin and soft tissue infections, urinary tract infection and respiratory tract infection. Cefpodoxime is being used as a step down from parenteral cephalosporin. The recommended dose is 8-10 mg/kg/d in a single or two doses. Different schedules have been given for different infections. The drug is safe, effective as a short course (5 vs. 10 days). With a low incidence of side effects, and twice a day dosing, it proves to be a useful drug.

Microdialysis is a technique that allows the measurement of concentrations of free antibiotic in tissue. The free antibiotic concentration is responsible for the antibacterial effect at the target site. We used microdialysis in animal and human studies to investigate the tissue penetration of cefpodoxime. In the animal study, total plasma and free muscle and lung concentrations of cefpodoxime were measured after male Wistar rats had received either 10 mg/kg or 20 mg/kg i.v. cefpodoxime over 5 h or a continuous i.v. infusion of 260 microg/h cefpodoxime after a loading dose of 6 mg/kg. Free muscle concentrations of cefpodoxime were similar to free lung concentrations and therefore provided a surrogate measure of cefpodoxime concentrations at the pulmonary target site. In an open, randomized, two-way crossover, single-dose study in six healthy male volunteers, total plasma and free muscle concentrations were measured after a single oral dose of cefpodoxime 400 mg or cefixime 400 mg. The total plasma concentrations of each antibiotic were similar and higher than free muscle concentrations. The tissue penetration of cefpodoxime was, however, greater than that of cefixime, as shown by two-fold higher peak free muscle concentrations after dosing with cefpodoxime than with cefixime (2.1 mg/L versus 0.9 mg/L). In addition, the area under the curve for tissue (AUC(t)) of cefpodoxime (400 mg) was more than double that of cefixime (400 mg), based on free antibiotic concentrations (15.4 mg x h/L versus 7.3 mg x h/L). These findings indicate that, taking into account pharmacokinetic/pharmacodynamic considerations, cefpodoxime is likely to be more efficacious than cefixime, due to its greater tissue penetration.

Background: The excretion of medicated drugs into saliva may disturb the oral environment and antibiotic excretion into saliva appears to be regulated by many factors that have not been fully explored., Methods: Excretion of four cephem antibiotics into saliva was examined in healthy volunteers and rats, using high-performance liquid chromatography, and the relationship between excretion levels and plasma protein-binding activities of the antibiotics was investigated., Results: Following addition of 50 microgram/ml of each antibiotic to human plasma, protein binding rates (PBRs) of cefuzonam (CZON, molecular weight (MW): 535.58), cefotaxime (CTX, MW: 477.45), flomoxef (FMOX, MW: 518.45) and cefozopran (CZOP, MW: 551.99) were 87.8 +/- 1.2, 70.8 +/- 0.8, 36.2 +/- 0.5 and 8.3 +/- 0.3%, respectively. In rat plasma, PBRs of the four antibiotics were 94.0 +/- 0.5, 62.1 +/- 1.4, 54.0 +/- 0.8 and 6.0 +/- 0.8%, respectively. Similar PBRs were observed when the antibiotic concentration was increased to 100 and 200 microgram/ml. CZOP was most rapidly excreted into saliva and had the highest concentration in saliva among the tested antibiotics, while the plateau level of CZON was the lowest. The excreted levels of each antibiotic in saliva, when locally perfused through the rat facial artery, were inversely associated with each PBR. Similarly, the ratios of antibiotic concentration in saliva to rat plasma were almost constant for each antibiotic, revealing an inverse relationship with PBRs., Conclusion: These results appear to indicate that low molecular weight antibiotics are excreted into saliva through passive diffusion, inversely relating to their PBRs, and that high concentrations of antibiotics in the saliva have the potential to change the oral ecological environment.

The effects of pretreatment with the gastrointestinal stimulant domperidone and the suppressant scopolamine butylbromide on the absorption of AS-924, a novel prodrug-type cephem antibiotic, were investigated in six healthy adult male volunteers by a cross-over method. The T(max) of ceftizoxime (CTIZ), the active moiety of AS-924, was slightly prolonged by scopolamine butylbromide (T(max)=1.8 vs. 1.5 h for the group without pretreatment). However, there were no significant differences in pharmacokinetic parameters including T(max), cumulative urinary excretion rates of CTIZ and cumulative urinary excretion rates of pivaloylcarnitine for 12 h after the dosing between the pretreated and control groups. Domperidone did not affect the absorption of AS-924.

The effect of pretreatment with ranitidine, an antacid, on the absorption of AS-924, a novel prodrug-type cephem antibiotic derived from ceftizoxime (CTIZ), was examined in eight healthy adult male volunteers by the cross-over method, using cefteram-pivoxil (CTER-PI) as the control drug. The C(max) and area under the concentration (AUC) values and cumulative urinary excretion rate (0-24 h) of cefteram (CTER) after administration of CTER-PI decreased by 32, 38 and 37%, respectively, in the ranitidine pretreatment group whereas those of AS-924 were not affected by the antacid. The urinary levels of pivaloyl-carnitine determined to evaluate the solubility of these antibiotics in the gastrointestinal tract suggested that this was not affected by ranitidine. These results indicate that the absorption of CTER-PI was affected by pretreatment with ranitidine largely due to inactivation of this antibiotic in the gastrointestinal tract at high pH rather than to a decrease in solubility. In contrast, isomerization of AS-924 was hardly induced by the elevation of pH, thus demonstrating that AS-924 was less likely to be affected by pretreatment with antacids.

The effect of the quantity of water ingested concomitantly with drugs, on the absorption of AS-924, a novel prodrug-type cephem antibiotic, was studied in five healthy adult volunteers by a cross-over method, using cefteram-pivoxil (CTER-PI) as the control drug. In addition, the effect of milk on the absorption of AS-924 was also investigated. The absorption of CTER-PI was significantly reduced when administered together with 30 ml of water compared with its absorption when administered together with 150 ml of water, whereas no such reduction was found in the case of AS-924. Ingestion of milk did not significantly affect the absorption of AS-924. These results confirm that absorption of AS-924 after oral administration is not likely to be affected by the quantity of water taken concomitantly with the drug, nor by milk.

The effects of food intake and age on intestinal absorption of AS-924, a novel prodrug-type cephem antibiotic, were examined in 16 healthy adult volunteers (eight young volunteers and eight elderly volunteers) by the cross-over method, using cefpodoxime proxetil (CPOD-PR) as the control drug. The gastrointestinal absorption of AS-924 and CPOD-PR was increased slightly by food intake and the extent of increase was slightly greater after administration of CPOD-PR. The absorption of AS-924 was not affected by age, whereas intestinal absorption of CPOD-PR increased with age. In conclusion, these results confirmed that AS-924 has the unique characteristics as a novel prodrug and that its absorption is less likely to be affected by food intake and age.

To investigate the effects of gastrectomy on the absorption of drugs, the blood concentrations of the active moieties, cefcapene (CCAP) and ceftizoxime (CTIZ), were determined in 36 gastrectomized patients after oral administration of cefcapene pivoxil (CCAP-PI) and AS-924, prodrug type cephem antibiotics with different solubility-profiles. In patients with gastrectomy, the C(max) and AUC for CCAP-PI whose solubility depended on the acidity of gastric juice, were lower than in the controls; whereas those for AS-924 were comparable with values in the control group. The T(max) was affected by the extent of gastrectomy; the T(max) value was the lowest in patients who had undergone total gastrectomy Roux-Y, followed by Billroth II and Billroth I procedure of subtotal gastrectomy. These results indicate the need to select drugs and to instruct gastrectomized patients regarding dosage and administration, taking the pharmacokinetics of drugs into consideration.

AS-924 is an oral prodrug of the antibiotic ceftizoxime (CTIZ), a parenteral use cephalosporin. This novel prodrug, produced by esterifying CTIZ with a lipophilic pivaloyloxymethyl (POM) group and introducing a water soluble L-alanyl group, is expected to increase the bioavailability and thereby, augment the antibacterial activity of CTIZ in vivo compared with existing prodrugs. To study the effect of the L-alanyl group in AS-924 on its bioavailability, the plasma concentration profiles of CTIZ in dogs were examined following the dosing of AS-924 and CTIZ-POM, in powder form, after pretreatment with the antacid ranitidine, and following the dosing of AS-924 after pretreatment with a gastrointestinal motility stimulant metoclopramide or suppressant scopolamine butylbromide. The absorption rate of AS-924 was constant under these different conditions due to its unique balance of lipophilicity and water solubility. CTIZ is as antibacterially active as pre-existing oral cephalosporins against Gram-positive clinical isolates, while being more active against all Gram-negative isolates-particularly Enterobacteriaceae and Haemophilus influenzae. A simulation model for the eradication profile of bacteria in computer programmed pharmacokinetic (PK) system was carried out to study the antibacterial action of CTIZ in human. CTIZ was proven to eradicate Streptococcus pneumoniae and H. influenzae effectively, while cefpodoxime (CPOD), the active moiety of CPOD proxetil, eradicated S. pneumoniae, but not H. influenzae. These results confirm that, AS-924 is a potent oral antibiotic and would be expected to be clinically effective and efficient.

We investigated the effect of infusion rate and experimental renal failure on the pharmacodynamics of cefoselis (CFSL)-induced seizures. As an animal model of CFSL-induced seizures, male Wistar rats received an intravenous infusion of CFSL at one of three different rates (1.4-5.8 g/h/rat) until the onset of maximal seizures (which occurred after 8.0 to 36.0 min of infusion). Samples of cerebrospinal fluid (CSF), blood (for serum), and brain were obtained immediately after stopping infusion of CSFL. The serum concentration of CFSL at the onset of seizures increased with increasing infusion rate, but brain and CSF concentrations of CFSL at the onset of seizures were not affected by the infusion rate. Ureter-ligated (UL) and control rats received an intravenous infusion of CFSL at 1.4 g/h/rat until the onset of seizures. Then the same procedure as used to determine the effect of infusion rate on the concentrations of CFSL was carried out. Renal failure was associated with a significant decrease in the amount of CFSL required to induce seizures. Serum, brain, and CSF concentrations of CFSL in UL rats were significantly lower than those in control rats. These results indicate that the experimental strategy and animal model in this investigation would be useful to assess the effects of diseases and other variables on the pharmacodynamics of CFSL-induced seizures and that renal failure is one of the risk factors for neurotoxicity of CFSL.