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A gradient elution high-performance liquid chromatographic method with a diode array detector is introduced for the first time for the simultaneous estimation of three drugs, namely, oxytetracycline hydrochloride (OXT), lidocaine (LDC), and bromhexine hydrochloride (BRH), in a veterinary formulation (OxyClear® solution) that contains many interfering additives. The method used a C-8 column. The chromatographic eluting solution included acidified water (0.1% trifluoroacetic acid in water) and acetonitrile at a 1-ml/min flow rate and 254 nm as a nominated detection wavelength. The chromatographic process was assessed in terms of linearity, precision, accuracy, LOD, and LOQ. OXT, LDC, and BRH were linear in the range of 1-60, 5-100, and 1-60 μg/ml, respectively. The three drugs were determined successfully without the interference of three excipients having UV absorbances. Furthermore, the purities of the peaks of the three drugs were confirmed by comparing the UV spectra of investigated peaks to the UV reference spectra in Clarke's Analysis of Drugs and Poisons. The greenness value of the method was 0.69 with a faint green-colored pictogram using the AGREE tool. These merits recommend the application of the planned method in QC laboratories for purity testing and concentration assays for the pure drugs and commercial formulations., (© 2021 Deutsche Pharmazeutische Gesellschaft.)

For the first time in China, the chemical profiling of cocaine specimens was performed at the National Narcotics Laboratory. An ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry (UHPLC-QTOF-MS) method was developed and validated for simultaneous analysis of 14 cocaine alkaloids and 5 main adulterants. Among them, ecgonine methyl ester, ecgonine, benzoylecgonine, and norcocaine were identified by comparing with the standard materials; tropacocaine, 3,4,5-trimethoxycocaine, cis-/trans-cinnamoylcocaine were tentatively identified based on the exact masses of protonated molecules and product ions; six unidentified alkaloids of 182/1.47, 316/9.54, 659/9.85, 316/9.87, 420/10.34, and 420/10.85 were marked with 'extracted mass/retention time' for convenience. Minimum sample preparation and analysis time were required, which was suitable for routine analysis. Based on the semi-quantitative data set of 14 alkaloid impurities in 131 linked/unlinked cocaine samples, 50 combinations of pretreatment methods and distance/correlation measurements were tested for their potential discrimination power for cocaine profiling, and Logarithm/Pearson exhibited the best result. After hierarchical cluster analysis (HCA), 183 cocaine samples collected from 2011 to 2015 were classified into 7 major groups. Moreover, 37 groups of linked samples were found within and between provinces, which provide intelligence for the case connection and revealing of the distribution networks. Our results highlighted the practical utilities of drug profiling, especially to support the investigation through operational intelligence and to improve the knowledge related to the drug trafficking through strategic intelligence. Copyright © 2016 John Wiley & Sons, Ltd., (Copyright © 2016 John Wiley & Sons, Ltd.)

A simple, isocratic, high-resolution and prompt HPLC-PDA method was developed and validated for the simultaneous quantification of prilocaine (PCL) and lidocaine (LCL) hydrochlorides in in vitro buccal iontophoresis-driven permeation studies. A reversed-phase C18 column (250 mm x 4.6 mm, 3μm, 110Å) was used for the chromatographic separation. The mobile phase contained acetonitrile: 0.1M sodium phosphate buffer, pH 7.0 (1:1, v/v), plus 0.05% (v/v) diethylamine. The isocratic flow rate was set at 1 mL/min and the detection wavelength was 203 nm. PCL and LCL eluted in 8.9 min and 13 min, respectively, and the system suitability parameters varied within an acceptable range. The method was selective, sensitive, precise, accurate and robust, producing a linear plot at the concentration range of 0.25 to 10 µg/mL. The application of this method was demonstrated by a significant enhancement of the permeation of PCL and LCL with the application of iontophoresis (1 mA/cm(2) per 1 h) through isolated porcine esophageal epithelium. The amount of the drug retained in the epithelium also increased with the application of an electrical current. Copyright © 2015 John Wiley & Sons, Ltd., (Copyright © 2015 John Wiley & Sons, Ltd.)

The potential and applicability of UHPSFC-MS/MS for anti-doping screening in urine samples were tested for the first time. For this purpose, a group of 110 doping agents with diverse physicochemical properties was analyzed using two separation techniques, namely UHPLC-MS/MS and UHPSFC-MS/MS in both ESI+ and ESI- modes. The two approaches were compared in terms of selectivity, sensitivity, linearity and matrix effects. As expected, very diverse retentions and selectivities were obtained in UHPLC and UHPSFC, proving a good complementarity of these analytical strategies. In both conditions, acceptable peak shapes and MS detection capabilities were obtained within 7 min analysis time, enabling the application of these two methods for screening purposes. Method sensitivity was found comparable for 46% of tested compounds, while higher sensitivity was observed for 21% of tested compounds in UHPLC-MS/MS and for 32% in UHPSFC-MS/MS. The latter demonstrated a lower susceptibility to matrix effects, which were mostly observed as signal suppression. In the case of UHPLC-MS/MS, more serious matrix effects were observed, leading typically to signal enhancement and the matrix effect was also concentration dependent, i.e., more significant matrix effects occurred at the lowest concentrations., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Topically applied tetracaine is a local anaesthetic. A novel HPLC method for the rapid and sensitive analysis of tetracaine was developed and compared with a short end direction capillary zone electrophoresis (CZE) method. The method was developed and validated for the separation and quantification of tetracaine in skin samples removed by 'tape-stripping'. Tetracaine was extracted from tape with 100% methanol, which was then diluted to 50% with water for injection. Tetracaine and the internal standard, procaine, were separated on a reversed-phase Luna PFP(2), 3 µm, 150 × 4.6 mm column at ambient temperature using isocratic elution with KH2 PO4 buffer (pH 2.5) and methanol (35:65, v/v). The flow rate was 1 mL/min, with detection at 312 nm. The limit of quantification for tetracaine was 0.03 µg/mL. Calibration lines were linear with r(2) values >0.99. The within- and between-assay imprecision and the percentage of inaccuracy for the QC samples including lower and upper limits of quantitation were <6 and <10%. The absolute mean recovery of tetracaine was >92%. Compared with CZE, the mean percentage error and the absolute mean percentage error were 0.62 and 6.29, respectively. The two methods were compared in a number of pharmacokinetic studies., (Copyright © 2014 John Wiley & Sons, Ltd.)

An HPLC method with amperometric detection was developed for analysis of two local anesthetics (lidocaine and benzocaine) in products for delaying ejaculation illegally marketed in Polish sex shops. Chromatographic elution on an RP column C18 with mobile phase composed of acetate buffer with acetonitrile, provides an optimal separation not only of active substances but also electroactive preservatives which are occasionally added to cosmetic creams (methylparaben and propylparaben). Application of glassy carbon electrode as a working electrode and a procedure with pulsed potential waveforms enables a sensitive, accurate measurement within a relatively short analysis time (250 s). This method has been successfully employed for the determination of local anesthetics in products under investigation. The obtained results show that most samples contained therapeutic concentrations of lidocaine or benzocaine. According to European law, a sale of products containing lidocaine or benzocaine outside the pharmacy sector is forbidden.

The pharmaceutical combination of miconazole nitrate (MZ) and lidocaine hydrochloride (LD) is used in the curative and prophylactic therapy of the oral and gastro-intestinal infections caused by Candida albicans. To the best of our knowledge, no attempts have yet been made to assay this combination by any analytical method. A simple and selective high-performance liquid chromatography-diode array detection (HPLC-DAD) stability-indicating method was developed for the simultaneous determination of MZ and LD in their combined formulation. Effective chromatographic separation was achieved using a Zorbax SB-C8 column with gradient elution of the mobile phase composed of 0.05 M phosphoric acid and acetonitrile. The gradient elution started with 25% (by volume) acetonitrile, ramped up linearly to 65% in 6 min, then kept constant until the end of the run. The mobile phase was pumped at a flow rate of 1 mL/min. The multiple wavelength detector was set at 215 nm and analytes were quantified by measuring their peak areas. The retention times for LD and MZ were approximately 4.1 and 8.4 min, respectively. The reliability and analytical performance of the proposed HPLC procedure were statistically validated with respect to linearity, ranges, precision, accuracy, selectivity, robustness, detection and quantification limits. Calibration curves were linear in the ranges of 5-100 µg/ml for both drugs with correlation coefficients > 0.999. Both drugs were subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. The proposed method proved to be stability-indicating by the resolution of the two analytes from the related substance and potential impurity (2,6-dimethylaniline) and from the forced-degradation products. The validated HPLC method was applied to the analysis of MZ and LD in the combined oral gel preparation, in which the two analytes were successfully quantified and resolved from the pharmaceutical additives. The proposed method made use of DAD as a tool for peak identity and purity confirmation., (© The Author [2012]. Published by Oxford University Press. All rights reserved.)

Quantitative structure-retention relationships (QSRR) were proposed for Separon SGX C18 and Separon SGX Phenyl columns using physico-chemical molecular descriptors for the compounds, which are potential local anaesthetic drugs. Chemometrical methods were used for the QSRR studies of the HPLC retention factor k of 59 esters of alkoxyphenylcarbamic acid, which exhibit surface and/or infiltration anaesthetic activity. Four separation systems were used: phenyl column and acetonitrile/water mobile phase, phenyl column and methanol/water mobile phase, C18 column and acetonitrile/water mobile phase, and C18 column and methanol/water mobile phase. The values of logP and logS and ¹³C and ¹H NMR chemical shifts were simulated and utilized in calculating the corresponding QSRR models and predicting the retention factors by artificial neural networks (ANN). In addition, principal component analysis and cluster analysis were used for a closer characterization of alkoxyphenylcarbamic acid esters. The proposed ANN models, based on optimally selected species descriptors, showed a high degree of correlation between k predicted and k measured. The intercepts and the slopes of the obtained dependences were close to the theoretically expected values of 0 and 1, respectively., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A simple and rapid high-performance liquid chromatography method coupled with UV detector was developed and validated for the simultaneous determination of ropivacaine, bupivacaine and dexamethasone in biodegradable poly(lactic-co-glycolic acid) (PLGA) microspheres within 11 min. Chromatographic separation was performed on a XDB-C(18) column using a mobile phase comprised of acetonitrile-NaH(2)PO(4) buffer (pH 3.5, 30 mM) (30:70, v/v) with a flow rate gradient program. The method was in good linearity (r>0.999) over the range of 0.025-40.0 microg/ml for ropivacaine and bupivacaine, and 0.05-40 microg/ml for dexamethasone. The method was proved to be precise with intra- and inter-day precision less than 3.0% and 6.0% for all drugs and accurate with intra- and inter-day accuracy between -8.0% to 4.5% and between -5.0% to 5.5% for all drugs. The assay was rapid, simple and easy to apply. Therefore, it was very suitable for routine determination and quality control of ropivacaine, bupivacaine and dexamethasone in PLGA microspheres.

An RP-HPLC method has been optimized and validated for the simultaneous determination of hydrocortisone acetate and of lidocaine in suppositories. For the method optimization, response surface methodology was applied, and the obtained model was tested using analysis of variance. The optimal separations were conducted on a Beckman-Coulter 150 x 4.6 mm, 5 microm particle-size column at 20 degrees C. The mobile phase was methanol-water (65 + 35, v/v), pH adjusted to 2.5 with 85% orthophosphoric acid, with a flow rate of 1.0 ml/min. UV detection was performed at 250 nm. Phenobarbital was used as an internal standard. The method was validated for selectivity, linearity, precision, and robustness.

A simple high-performance liquid chromatography (HPLC) method with ultraviolet diode array (UV-DAD) and electrospray ionisation mass spectrometry (ESI-MS) detection has been developed for the determination of vardenafil, sildenafil, tadalafil, testosterone, procaine, lidocaine, prilocaine, and benzocaine in cosmetic creams sold as promising remedies for male erectile dysfunction and female genitals stimulation. The presence of these substances in commercial cosmetic samples is prohibited. Aliquots (1 g) of the cosmetic creams under investigation were diluted 1:100 in methanol, subjected to ultrasonic treatment, added with benzoic acid as internal standard, and analyzed by HPLC-DAD and HPLC-ESI-MS after a further 1:1000 dilution. The compounds were separated by reversed phase chromatography with water (0.02% trifluoroacetic acid) and acetonitrile gradient elution and detected by UV-DAD at 228, 255 and 290 nm and by ESI-MS positive ionisation mode. Benzoic acid was used as internal standard. Linearity was studied with UV-DAD detection from 2.5-7.8 to 250 microg/g range, depending on the different compounds and with ESI-MS in the 3.3-8.9 to 250 ng/g range. Good determination coefficients (r(2) > or = 0.99) were found in both UV-DAD and ESI-MS. Limits of quantifications ranged between 2.5 and 7.8 microg/g for HPLC-UV-DAD assay and between 3.3 and 8.9 ng/g for HPLC-ESI-MS assay depending on different analyzed substances. At three concentrations spanning the linear dynamic ranges of both UV-DAD and ESI-MS assay, mean recoveries were always higher than 90% for the different analytes and intra-assay and inter-assay precision always better than 15% and 12%. This method was successfully applied to the analysis of substances under investigations present in cosmetic creams, freely sold on the Internet web-sites.

A high-performance liquid chromatography-diode array detection method was developed and validated to simultaneously determine tramadol (TMD), metamizole (MTZ), ropivacaine (RPV), and bupivacaine (BPV) in the presence of 4-methylaminoantypirine (4-MAA), the metabolite of MTZ, in analgesic mixtures samples used in Patient Controlled Analgesia (PCA). Chromatographic separation is achieved with a C-18 column using a mixture of ACN-methanol-water adjusted to pH 3.0 with NaH(2)PO(4) 0.05M (10:25:65 v/v) in an isocratic mobile phase at a flow rate of 0.8 mL/min. 0.5 mg/mL of Na(2)SO(3) in the water of the mobile phase was necessary to prevent the fast MTZ hydrolysis process to 4-MAA. Ultraviolet-diode array detection was used and chromatograms were registered at the wavelength of 230 nm. The method was linear in the range of 2.2-80.0 mg/L for TMD, 4.1-140.0 mg/L for MTZ, 2.3-40.0 mg/L for RPV, and 2.9-40.0 mg/L for BPV. Validation of the method was made in terms of accuracy, intra- and interday precision, as well as quantification and detection limits. The hydrolysis of MTZ to 4-MAA was studied and verified by mass spectrometry. The developed method was used successfully to evaluate the chemical stability of binary analgesic TMD mixtures with MTZ, RPV, or BPV. The mixtures were tested at standard concentrations used in PCA and in different storage conditions. When mixtures contained MTZ, a chromatographic peak from the metabolite 4-MAA was always detected in the chromatograms.

A simple, rapid, accurate, precise and specific analytical method has been developed, validated and applied for determination of cinchocaine in guinea pig and albino rabbit dorsal skins, after in vivo application of cinchocaine formulations. Extraction was performed using a solvent mixture of ethanol and 0.1 M hydrochloric acid (90:10; v/v). Samples were chromatographed on Spheri-5, RP(18) column with a particle size of 5 microm and 220 mm x 4.6 mm i.d. The mobile phase was a mixture of acetonitrile and triethylamine phosphate buffer (pH 2.8; 0.04 M) (60:40, v/v). UV detection was carried out at 247 nm and the run time was 6 min with typical retention time of cinchocaine of 3.63 +/- 0.02 min. Specificity was demonstrated, showing that the cinchocaine peak was free of interference from skin endogenous components. The detector response was found to be linear in the concentration range 0.96-56.00 microg/mL with a coefficient of correlation r = 0.99996. The relative standard deviations of within- and between-day analyses were all below 5%. The drug extraction procedure was validated. Satisfactory recoveries with relative standard deviation values below 5% were obtained, indicating efficient quantitative reproducible extraction procedure., ((c) 2006 John Wiley & Sons, Ltd.)

The chromatographic retention and membrane activity relationships of local anesthetics were studied to address the possible mechanisms for structure specificity and inflammation-associated decrease of their effects. Five representative drugs (3 mM for each) were reacted with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine liposomes in 25 mM potassium phosphate buffer (pH 5.9-7.9, containing 100 mM NaCl and 0.1 mM EDTA) for 10 min at 37 degrees C and the membrane fluidity changes were analyzed by measuring fluorescence polarization with 1,6-diphenyl-1,3,5-hexatriene. Their capacity factors were determined on octadecyl-, octyl- and phenyl-bonded silica columns with a mobile phase consisting of 25 mM potassium phosphate buffer (pH 5.9-7.9, containing 100 mM NaCl and 0.1 mM EDTA)-methanol (30:70, v/v) at a flow rate of 1.0 ml/min and at a column temperature of 37 degrees C and diode-array detection. Mepivacaine, prilocaine, lidocaine, ropivacaine and bupivacaine fluidized membranes in increasing order of intensity, which agreed with their clinical potency. The relative degree of membrane fluidization correlated with that of retention on an octadecyl stationary phase more significantly than the other phases. Both membrane-fluidizing effects and capacity factors decreased by lowering the reaction and mobile phase pH, being consistent with the hypothesis that anesthetic potency is reduced in inflammation because of tissue acidity. Reversed-phase liquid chromatography appears to be useful for estimating the structure-specific and pH-dependent membrane-fluidizing effects of local anesthetics.

An HPLC method with ultraviolet detection coupled with a solid-phase extraction sample clean up was developed for the analysis of five local anaesthetics and four antihistaminics in cosmetic products. The presence of these compounds in commercial cosmetic samples is fordbidden. Extracts from real samples were applied to a solid-phase extraction C18 cartridge, and the analytes were eluted with 8:2 (v/v) acetonitrile/water containing 1% trifluoroacetic acid. HPLC separation was then performed for the identification and determination of the analytes using a Purospher RP-18 column, two gradient eluting systems and a photodiode-array detector. The accuracy of the method was verified by spiking experiments on home-made cosmetic samples. The analytical recoveries were satisfactory.

An isocratic reversed-phase high performance liquid chromatographic method is developed and validated for the determination of 2-(diethylamino)-N-(2,6-dimethylphenyl) acetamide (0.3%, w/w) in a gel formulation. The chromatographic separation is achieved with potassium phosphate buffer (pH 7.0)-acetonitrile (47:53, v/v) as mobile phase, a C(18) column, and UV detection at 254 nm. The calibration curve is linear (r(2) = 1.000) from 20-140% of the analytical concentration of 1.4 microg/mL. The mean percent relative standard deviation values for intra- and interday precision studies are < 1%. The recovery ranges 99.95-100.23% from a gel formulation. The method is specific and successfully routinely used in quality control for the analysis of bulk gel samples and final product release.

A reverse-phase high-performance liquid chromatographic (HPLC) method to determine hydrocortisone acetate, hydrocortisone hemisuccinate and lidocaine is described in this paper. The separation was made in a LichrCART C(18) column using a methanol-NaH(2)PO(4)/Na(2)HPO(4) (0.1 mol L(-1)) (pH=4.5) buffer solution as a mobile phase in isocratic mode (60:40 (v/v)). The mobile phase flow rate and the sample volume injected were 1 mL min(-1) and 20 micro L, respectively. The detection was made with a diode-array detector measuring at the maximum for each compound. Quantification limits ranging from 0.18 to 0.84 micro g L(-1) were obtained when the peak area was measured. The method was applied in pharmaceutical formulations that were compared with those obtained by through multivariate regression spectrophotometry and micellar capillary electrophoresis (MEKC). HPLC results are in accordance with the results obtained by MEKC. The spectrophotometric method was suitable only for synthetic samples.

Two methods are presented for the determination of benoxinate HCI and its acid and alkali-induced degradation products using first derivative (1D) spectrophotometry with zero-crossing measurements and liquid chromatography. Benoxinate HCl was determined by measurement of its first derivative amplitude in mcllvaine's-citric acid phosphate buffer pH 7.0 at 268.4 and 272.4 nm in the presence of its alkali- and acid-induced degradation products, respectively. The acid- and alkali-induced, degradation products were determined by measurement of their first derivative amplitude in the same solvent at 307.5 nm. The LC method depends upon using a mu bondapak CN column with a mobile phase consisting of acetonitrile-water triethylamine (60:40:0.01, v/v) and adjusted to apparent pH 7. Quantitation was achieved with UV detection at 310 nm based on peak area. The proposed methods were utilized to investigate the kinetics of the acidic and alkaline degradation processes at different temperatures. The pH-rate profile of degradation of benoxinate HCl in Britton-Robinson buffer solutions was studied.

A method has been developed for the quantitative determination of low concentrations of sufentanil citrate (1.0 microg/ml), in the presence of bupivacaine hydrochloride (0.125%), in the quality control of pharmaceutical preparations. The main problem in analysis of this combination is the low concentration of sufentanil citrate in the presence of relatively high concentrations of bupivacaine hydrochloride. This paper describes the validation of a HPLC method of sufentanil citrate in an admixture with bupivacaine hydrochloride using solid phase extraction (SPE). The optimized method shows good linearity, precision and accuracy. The limits of detection (0.09 microg/l) and quantification (0.29 microg/l) for sufentanil citrate are lower than the maximal accepted limits. This method is currently used in stability studies.

Two methods are presented for the determination of cinchocaine HCl in presence of its acid-induced degradation product using first (1D) derivative spectrophotometry and high-performance liquid chromatography. Cinchocaine HCl was determined by measurement of its first derivative amplitude at the zero crossing point of 2-hydroxyquinoline-4-carboxylic acid diethylaminoethylamide as its acid degradation product (at 333.5 nm). The HPLC method depends upon using a mu Bondapak C18 column at ambient temperature with a mobile phase consisting of acetonitrile--0.01 M sodium acetate trihydrate (45:55, v/v) containing 0.06% (w/v) heptane sulphonic acid sodium salt and adjusted to apparent pH 4.5 with acetic acid at a flow rate 2 ml min-1. Quantitation was achieved with UV detection at 254 nm based on peak area. The HPLC method was applied for simultaneous determination of cinchocaine HCl, methylparaben and propylparaben. The two proposed methods were successfully applied to the determination of the cinchocaine HCl in laboratory-prepared mixtures in the presence of its acid degradation product and in cream. Moreover, the proposed methods were utilized to investigate the kinetics of the acid degradation process at different temperatures and the apparent pseudo first-order rate constant, half-life and activation energy calculated.

A sensitive and selective bioanalytical method for simultaneous determination of diclofenac and oxybuprocaine in human aqueous humor using reversed-phase HPLC and electrochemical detection is described. Chromatographic separation was achieved by using a Regis SPS 100 RP-8 column (5 microns; 150 x 4.6 mm I.D.). This support is coated with a hydrophilic polyoxyethylenepolymer. It allows protein-containing samples to be injected directly onto the column. The electrochemical detector permit a detection limit of 500 pg diclofenac per ml (daily relative standard deviation 6.3%) and 50 ng oxybuprocaine per ml (daily R.S.D. 2.6%), respectively. Results of administered and measured drug-concentrations in time dependent decrease are presented.

A rapid and accurate reversed-phase HPLC method for separation and simultaneous quantitation of some local anesthetics, antihistamines and preservatives in skin cosmetics is described. The investigated compounds (procaine, lidocaine, mepivacaine, bupivacaine, benzocaine, brompheniramine, benzoic acid, methyl, ethyl and propyl p-hydroxybenzoate, o-phenylphenol) are extracted by ultrasonic treatment in methanol from cosmetic form. Methanol-aqueous orthophosphoric acid (pH 2.8) containing 0.9% dibutylamine has been used as eluent. The influence of different percentages of methanol on chromatographic behaviour has been studied using both isocratic conditions and gradient elution program. The gradient program allows a rapid resolution and quantitation also for acidic preservatives.