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Animal pharmacokinetic/pharmacodynamic studies are commonly used to provide meaningful preclinical information that can be utilized by the scientific community to conduct first-in-human studies. Poor presentation and interpretation of the data limit study reproducibility, and may result in rejection when the study is submitted to a journal, leading to loss of time and resources at multiple levels. In addition, inconsistencies in reporting the results of animal studies may limit the ability to extrapolate the experimental findings to humans. A few guidelines have been published to make the reporting of animal studies consistent; however, strict implementation of these guidelines by authors, reviewers, and journal editors is still lacking. In an attempt to make the reporting of animal pharmacokinetic/pharmacodynamic studies consistent and improve the standard of reporting, this article provides guidelines that can be followed when submitting such studies to a journal. A detailed checklist, based on these guidelines, has been developed that can be used by the authors, reviewers, and editors to check if the required information is included in the manuscript. These guidelines can also be used for designing and performing such studies.

Regulatory agencies do not specify how to plan the sampling intervals in pharmacokinetics (PK) studies. Every interval between each sampling point forms one of the fractions of the area under the curve (AUC). The aim of this study is to propose a method of qualitative evaluation of PK studies, on the basis of the analysis of the partial AUC fields' values. For the pharmacokinetic analysis, average concentrations of high variability drug-itraconazole were used before (BO) and after sampling intervals optimization (AO). PK calculations were performed using Phoenix(TM) WinNonlin 6.3(®) (Certara L.P.) and in house software Biokinetica 4.0. Arithmetic formula and acceptance limit (AL%) was established, below which the mean of partial fields (MAF) value in PK study can be considered optimal. In case of MAF the CV% value before optimization was 125.35 and after the optimization 46.51. In the cases of AUC fractions for several partial fields BO data, the AL% value was exceeded. The values of AUC fractions did not exceed AL% established for AO data. The paper proposes an empirical method of quality assessment, made on the basis of the percentage of the AUC fractions. This method can be used in the quality assessment of PK studies., (© Georg Thieme Verlag KG Stuttgart · New York.)

Key elements of pharmacokinetics (PK) studies include both, the number of sampling points (NSP) as well as the spacing between the sampling points (SSP). Optimization of the SSP is discussed in guidelines of all key regulatory agencies (RA). Those however, provide only very general rules on how to properly distribute the NSPs in proposed PK studies. Here we demonstrate that the six sigma (SX) method can be effectively used to assess the quality of SSPs. We have tested a modified SX method analyzing 466 PK profiles from 16 studies including a total of 368 healthy volunteers. Non-compartmental modeling was used to estimate PK parameters. The arithmetic means of minimum and maximum values of SX obtained for each subject in all studies were 1.97 and 3.83, respectively. The method described here allows comparing quality of studies performed at different centers, even if they cover different chemical entities. We propose that the SX values can be used to assess quality of PK studies, what is consistent with recommendations of the RAs.

For many drugs administered per os, high variability in the concentration-time (C-T) values from first sampling to the phase of distribution may cause difficulty in pharmacokinetic analysis. Therefore, the aim of this study was to propose a method of transformation of C-T data, which would allow significantly reducing the standard deviation (SD) value of observed concentrations, without a statistically significant influence on the value of the mean for each sampling point in group. In the presented study, the lowest value of relative standard deviation of concentrations observed in the elimination phase and the value of precision of the used analytical method, were used to optimize the arithmetic, geometric means, median, and the value of SD obtained after single oral administration of itraconazole in human subjects. Non-compartmental modeling was used to estimate pharmacokinetic parameters. The analysis of SD pharmacokinetic parameters after C-T value optimization indicated more than twice the lower value of SD. After transforming the itraconazole data, lower variability of concentration data gives more selective pharmacokinetics profile in absorption and early distribution phase.

The aim of this study was to verify the values of maximal observed concentration (C max,obs) and the time, at which maximum concentration is observed (t max,obs) using the analysis of the absorption rate constant (k ab). It focused on the changes in concentration over time (C-T) for drugs, for which several peaks of concentration occur. In addition, the attempt was made to use Fibonacci sequence to facilitate the visual analysis of the dynamics in changes of concentration on C-T graphs. The analyses were conducted with the use of three hypothetical data groups (groups I, II and III), which had distinct C-T profiles, and with the in vivo data form healthy subjects (n = 10) taking part in a bioequivalence study, who was given a single oral dose of topiramate (100 mg). The comparison of hypothetical and real in vivo data demonstrated that for the C-T curves, in which there are several peaks of concentration C max,obs and t max,obs values can easily be miscalculated when the increase in concentration is not properly related to the appropriate absorption phase (63.2, 87.50, 96.88 %). It was also demonstrated that the data transformation with the use of Fibonacci sequence exposes slight differences in the observed concentration values in a semi-logarithmic scale. The results of this study show that in case of C-T curves with several peaks of concentration, the verification of C max and t max data obtained taking into account different absorption phases enables more precise evaluation of these parameters.

Many registration agencies and other organizations define how to calculate the elimination rate constant (kel) value. No validation procedures have been introduced to verify the correct selection of the concentration-time (C-T) points used for the kel calculation. The purpose of this paper is to discover whether kel analysis can be subjected to the condensed validation procedure and what acceptance criteria should be adopted for such a procedure. For the analysis, data collected during bioequivalence studies of 4 drugs were selected, including 2 highly lipophilic drugs (itraconazole, atorvastatin) and 2 weakly lipophilic drugs (trimetazidine, perindopril). Pharmacokinetic calculations were performed with the use of WinNonlin Professional v 5.3. Internal validation of the kel analysis using leave-one-out cross-validation was performed. The present analysis proves that the C-T selection process for the kel calculations cannot be automated. In each of the analysed data series there were such C-T sequences that did not meet even one of the validation criteria. This paper proposes 3 validation criteria which need to be met in order to confirm the optimal selection of C-T data to calculate kel: Q 2≥0.6, R2≥ 0.85, Q 2-R2<0.3, were Q 2 - squared cross-validated correlation coefficient, R2 - coefficient of determination). Application of the validation procedure for the kel analysis under discussion proves the accuracy of the calculations, even if repeated kel analysis is based on a different sequence of points in the elimination phase., (© Georg Thieme Verlag KG Stuttgart · New York.)

Guidelines published by the European Union Regulatory Authority, regarding the planning of bioequivalence studies, are the primary source of knowledge about the study design optimization. The goal of this paper is to compare the key elements (27 points) of bioequivalence study optimization based on a comparison of the two European Medicines Agency guidelines relating to medicines used for humans (HB) and to veterinary drugs (AB). In case of the latter, one can get the impression that the issues of species differences in relation to the physiology and anatomy have been completely ignored. Many details that the AB guideline omits are included in the new HB guideline and were present in many other guidelines from the last 20 years. Most have not been adopted by the AB document, even though they are the product of many years of work of many teams and specialists from various agencies in the regulatory affairs field., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The correlation between 52 physicochemical parameters and mean residence time (MRT) for 27 drugs used in human and dog were investigated. The physicochemical parameter values calculated provided a basis for deriving a series of arithmetic expressions, which were used to build a mathematical model describing the relationship between them and the MRT values. From the entire set of analyzed parameters, a subset of 14 was identified that contributed to the derivation of an arithmetic expression: Log(PSA - WPSA + ACID) x [XlogP - (LogKp - EAxLn(Caco2 + AMINE + SAF))] + (AMIDE + IP - FG) - Ln(MW + PISA) the value of which is highly correlated with the MRT value in dogs (P < .001) and allowed prediction of the MRT predicted (MRT(pred)). In humans, no correlation was found that allowed the calculation of MRT(pred). These results indicate that predicting the pharmacokinetics of any specific drug for humans based on pharmacokinetic data obtained in the dog should be undertaken with knowledge of the inherent limitations.

OBJECTIVE: Chronic pancreatitis (CP) is a disease leading to irreversible pancreas dysfunction. One of the main symptoms is pain. Many patients require pharmacological therapy which should be started with paracetamol or, in selected groups of patients, ketoprofen. If the effect of ketoprofen is irrelevant, patients receive tramadol. The aim of this study is the evaluation of ketoprofen and tramadol pharmacokinetics (PK) in CP patients. PATIENTS AND METHODS: 36 patients were divided into two groups: I - receiving ketoprofen (n=18; mean [SD] age, 48.61 [13.32] years; weight, 73.28 [20.48] kg), II - receiving tramadol (n=18; mean [SD] age, 46.78 [10.28] years; weight, 74.22 [14.04] kg, and BMI (Body Mass Index), 24.61 [4.51] kg/m²). The plasma concentrations of ketoprofen and tramadol with its active metabolite M1 (0-desmethyltramadol) were measured with the validated high-performance liquid chromatography method. RESULTS: The main PK parameters for ketoprofen were as follows: Cmax (maximum plasma concentration), 3.41 [2.32] mg/L; AUC0-inf (area under the plasma concentration-time curve from time zero to infinity), 10.45 [5.57] mg h/L; tmax (time to first occurrence of Cmax), 1.94 [1.25] h; Cl (clearance), 0.199 [0.165] L/kg·h, and Vd/kg (volume of distribution per kilogram of body weight), 0.71 [0.58] L/kg. The main PK parameters for TRM and M1 were as follows: Cmax, 226.4 [80.5] and 55.6 [23] ng/mL; AUC0-inf, 1903.3 [874.8] and 790.4 [512.4] ng⋅h/mL; tmax, 1.78 [0.73] and 2.67 [1.19] h, respectively. CONCLUSIONS: Chronic pancreatitis led to a decrease in the total amount of absorbed ketoprofen. Consequently, the analgesic effect of the drug may be weaker. Cmax of tramadol for most CP patients was within the therapeutic range associated with its analgesic activity. M1/TRM ratios for Cmax and AUC were unchanged. [ABSTRACT FROM AUTHOR]

1. The aim of this study was to determine if the pharmacokinetics (PK) of florfenicol (FF) undergo age-dependent changes in broilers. Since drug elimination depends on cardiovascular functions, a haemodynamic study was performed in parallel. 2. Broilers of 0.68, 1.27, 2.45 and 5.13 kg were administered FF in a single intravenous dose of 30 mg/kg body weight. Plasma drug concentrations were determined using high-performance liquid chromatography and PK parameters were calculated using a non-compartmental model. Echocardiography was used to measure haemodynamic functions. 3. During growth, the area under the drug concentration-time curve (AUCinf) increased from 25.7 ± 2.9 to 39.0 ± 8.0 mg h/l. Total body clearance (ClB) gradually decreased from 1.19 ± 0.14 to 0.80 ± 0.15 l/h/kg. Elimination half-life increased from 0.73 ± 0.08 to 1.07 ± 0.07 h, whereas volume of distribution (Vss) remained unchanged. Haemodynamic measurements revealed an increase in cardiac output, from 495 ± 65 to 1303 ± 306 ml/min, in the respective body weight groups. 4. Allometric models for PK and haemodynamic parameters were developed and validated. All models proved to be statistically significant; however, only models for ClBandVssmet stringent validation criteria. Model for ClBwas used to calculate an optimal dose for a given age group that provides uniform AUCinf. 5. Age-dependent change in FF kinetics may cause variability in therapeutic response under clinical conditions. A novel approach to the dosing protocol was proposed as a means of optimising therapeutic efficacy. [ABSTRACT FROM PUBLISHER]

Metamizole ( MT) is a pyrazolone nonsteroidal anti-inflammatory drug labelled for humans and animals. The aim of this study was to assess the pharmacokinetics of its active metabolites 4-methylamino-antipyrine ( MAA) and 4-amino-antipyrine ( AA) in male piglets after a single intramuscular injection of MT. Eight healthy male piglets were administered MT (100 mg/kg) intramuscularly. Blood was sampled at scheduled time intervals, and drug plasma concentrations evaluated by a validated HPLC method. MAA and AA plasma concentrations were quantitatively detectable from 0.25 to 48 h and 0.50 to 72 h, respectively, in 6 of 8 and 7 of 8 animals. The average maximum concentrations of MAA and AA were of 47.59 and 4.94 mg/ mL, respectively. The average half-lives were 8.57 and 13.3 h for MAA and AA, respectively. This study showed that the amount of MAA and AA produced in piglets is different to that in the animal species previously investigated. Further studies are necessary to understand whether these differences in MAA and AA plasma concentrations between animal species necessitate diverse therapeutic drug dosing. [ABSTRACT FROM AUTHOR]

Whereas interspecies variation in pharmacokinetics is a commonly investigated issue, variations in drug kinetics within a species are less documented. The aim of the study was to assess the influence of age-related changes in haemodynamics on the pharmacokinetics of metronidazole ( MTZ) and its hydroxy metabolite ( MTZ- OH) in turkeys. MTZ was administered intravenously and orally at a dose of 25 mg/kg. Plasma drug and metabolite concentrations were assessed by high-performance liquid chromatography, and pharmacokinetic parameters were calculated by noncompartmental analysis. Haemodynamic parameters (heart rate, stroke volume, cardiac output) were assessed by echocardiography and extraction ratio for MTZ was calculated based on total body clearance (ClB). Between the 5th and 15th week of age, ClB of MTZ decreased from 3.6 to 1.2 mL/min/kg causing a twofold increase in the mean residence time ( MRT) and elimination half-life (T1/2el). The MTZ- OH production decreased threefold and its MRT and T1/2el increased. Although heart rate significantly decreased with age, cardiac output increased. Extraction ratio was low in all age groups. It is concluded that significant age-dependent decrease in ClB of MTZ in turkeys resulted from decreased perfusion of the clearing organs and their reduced metabolic capacity. This phenomenon is probably species specific and may apply to other therapeutic agents. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the influence of growth on the pharmacokinetics of sodium salicylate ( SS) in male turkeys. SS was administered intravenously at a dose of 50 mg/kg. Plasma drug concentrations were assessed by high-performance liquid chromatography, and pharmacokinetic parameters were calculated by noncompartmental analysis. As the age increased from 6 to 13 weeks (body weight increase from 2.35 to 9.43 kg), median body clearance decreased from 1.34 to 0.87 ml/min/kg. This caused a significant increase in the median mean residence time from 3.42 to 4.44 hr. Elimination phase proved to be biphasic and two elimination half-lives ( T1/2el) were distinguished. Whereas T1/2el1 was found to increase with age by 128%, T1/2el2 represented a later but faster and less age-dependent phase of elimination (increase by 56% in the respective groups). Volume of distribution decreased with age. These effects may lead to different therapeutic response to SS in turkeys of different age and body weights. [ABSTRACT FROM AUTHOR]

Introduction: Quercetin is a polyphenolic flavonoid which has been used in traditional Chinese medicine as a natural therapeutic agent with a broad spectrum of activities (antioxidant, anticancer, neuroprotective, anti-inflammatory, antiviral and antibacterial). The aim of this study was to develop and validate a rapid and simple ultra-high-performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) method for the determination of quercetin in milk.

OBJECTIVE: Oxycodone is a semi-synthetic opioid with a stronger analgesic effect than morphine and codeine. The efficacy of this opioid in the treatment of postoperative pain has been proved in different groups of patients. The drug has a favourable adverse reaction profile, which encourages doctors and patients to use it more and more widely. The drug is also used in the patients who underwent an abdominal surgery, e.g. stomach resection. Gastrectomy leads to pathophysiological changes within the gastrointestinal tract, which may cause changes in the drug absorption. In consequence this leads to a change in the pharmacokinetics and effect of the drug. The aim of the research was an analysis of the pharmacokinetics of oxycodone from prolonged release tablet in patients after total gastrectomy. PATIENTS AND METHODS: The research was carried out on patients after gastrectomy with Roux-en-Y reconstruction. The patients (n=24; mean [SD] age, 67.6 [9.8] years; weight, 69.1 [13.6] kg; and BMI, 25.2 [4.0] kg/m²) received oxycodone in a prolonged release tablet in a single orally administered dose of 10 mg. Blood samples were collected within 12 h after the drug administration. The plasma concentrations of oxycodone and noroxycodone were measured with validated high-pressure liquid chromatography coupled with triple tandem mass spectrometery method. RESULTS: The main pharmacokinetic parameters for oxycodone in men (n = 14) and women (n = 10) were as follows: Cmax, 14.40 (3.76) and 11.54 (6.98) ng/ml (p = 0.2066); AUC0-∞, 157.87 (56.89) and 106.44 (61.31) ng'h/ml (p = 0.0460); tmax, 2.18 (0.58) and 2.15 (0.58) h (p = 0.8008), respectively. CONCLUSIONS: Total gastrectomy did not affect the pharmacokinetics of oxycodone administered in prolonged release tablets, but the exposure to the drug was significantly lower in women. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the pharmacokinetics and pharmacodynamics of ciprofloxacin in critically ill patients after the first intravenous administration of 400 mg. Material/methods. Plasma concentrations were measured in 20 critically ill patients (mean [SD]; age, 55.5 [16.5] years; weight, 80.3 [16.9] kg; and creatinine clearance, 110.0 [71.5] rnL/min). Four blood samples were drawn at the following time points 0, 0.5, 6, 8 hours after infusion. Ciprofloxacin concentrations were determined by high-performance liquid chromatography. Results. In the cases where ciprofloxacin was applied in targeted antibiotic therapy the minimum inhibitory concentrations (MIC) were ≤0.5 mg/l. The maximum and minimum plasma concentrations of ciprofloxacin were 1.74 (0.58-7.90) and 0.45 (0.16-2.96) mg/l, respectively. The main pharmacokinetic parameters for ciprofloxacin in the analyzed patients were as follows: kel,0.21 h-1; t1/2kel, 3.37h; AUC0-inf, 10.10mgxh/l; AUMC0-last, 15.36 mgxh²/1; MRT, 1.71 h; Vd, 214.8 1; Cl, 39.70 1/h. Considering the maximum value of MIC (0.5 mg/1) only 30% and 25% of analyzed patients had desired values of the PK/PD indexes AUIO125 and Cmax/MIC>10, respectively. Conclusions. The target plasma concentrations after the first dose of ciprofloxacin were reached only in a few critically ill patients. Considerable inter-subject variability for PK/PD parameters in ICU patients requires systematic monitoring. [ABSTRACT FROM AUTHOR]

The pharmacokinetics of florfenicol (FF), thiamphenicol (TP) and chloramphenicol (CP) after single intravenous (i.v.) or oral (p.o.) administration was studied in an independent cross-over study in broiler turkeys. All the fenicol antibiotics were administered at a dose of 30 mg/kg b.w. and their concentrations in plasma samples were assayed using the same validated high-performance liquid chromatography method. Pharmacokinetic parameters were calculated by a noncompartmental method. The kinetic profiles of the compounds were compared with the results of the structure–activity relationship. According to the proposed mathematical description, no differences in plasma clearance values for the studied antibiotics were observed. The mean residence time values of FF, TF, and CP after i.v. injection were 3.37 ± 0.63, 2.43 ± 0.29, and 2.12 ± 0.21 h, respectively. The mean values of Varea for FF (1.39 ± 0.31 L/kg) and TP (1.31 ± 0.19 L/kg) were similar, but significantly different from that of CP (1.04 ± 0.12 L/kg). The bioavailabilities of FF, TP, and CP after oral administration were 82%, 69%, and 45%, respectively. Differences in the bioavailability values of the compared fenicol antibiotics correspond to the ratio of the apolar/polar surface areas of their particles. [ABSTRACT FROM AUTHOR]