A Validated High-Performance Thin-Layer Chromatographic Method for the Simultaneous Determination of Zofenopril Calcium and Hydrochlorothiazide in the Presence of the Hydrochlorothiazide Impurities: Chlorothiazide and Salamide.

The chromatographic analysis of either process-related impurities or degradation products is very important in the pharmaceutical industry. In this work, a simple, selective, and sensitive HPTLC method was developed and validated for the simultaneous determination of zofenopril calcium (ZOF) and hydrochlorothiazide (HCT) in the presence of the HCT impurities: A) chlorothiazide (CT) and B) salamide, in raw materials and in pharmaceutical formulation. The separation was carried out on HPTLC silica gel 60 F254 using ethyl acetate-glacial acetic acid-triethylamine (10 + 0.1 + 0.1, v/v/v) as a developing system. The separated bands were scanned densitometrically at 270 nm. Polynomial equations were used for the regression. Calibration curves were constructed for ZOF, HCT, CT, and salamide in the ranges of 0.5-10, 0.2-4, 0.05-1.4, and 0.05-1.0 µg/band, respectively. Different parameters affecting the suggested method, including developing systems of varying composition/ratios and different detection wavelengths, were studied to achieve the best resolution and precision with good sensitivity. System suitability parameters were also tested. The proposed method was validated as per the International Conference on Harmonization guidelines and was successfully applied for the quantification of the studied drugs in their pharmaceutical formulation, with no interference from excipients observed. The results obtained by the developed HPTLC method were compared statistically with those obtained by the reported HPLC method using Student's t and F ratio tests, and no significant difference was obtained, indicating the ability of the proposed method to be used for routine analysis of drug product.

Stability of furosemide and chlorothiazide stored in syringes.

PURPOSE: The results of a study to determine the stability of solutions of furosemide and chlorothiazide over 96 hours are reported. METHODS: Chlorothiazide and furosemide were diluted in 5% dextrose USP to final concentrations of 10 and 1 mg/mL, respectively, and combined. In addition, sample solutions of chlorothiazide in dextrose, furosemide in dextrose, and dextrose alone were prepared for control purposes. The resulting solutions were analyzed immediately after preparation and 24, 48, 72, and 96 hours later using a liquid chromatography-tandem mass spectroscopy (LC-MS/MS) system with an electrospray ionization source. Mixtures and samples were diluted 10,000-fold prior to LC-MS/MS analysis so that concentrations of both drugs would be within the assay's linear range of detection. RESULTS: LC-MS/MS analysis showed that chlorothiazide typically eluted at 2.6 minutes and furosemide at 4.8 minutes. Each compound was degraded by exposure to strong ultraviolet light in a time-dependent manner. Both unmixed and mixed solutions retained over 90% of the original concentrations of chlorothiazide and furosemide for up to 96 hours. Furosemide and chlorothiazide are commonly used concomitantly to maximize diuresis in pediatric patients; the study findings suggest that solutions of furosemide and chlorothiazide can be combined in the same syringe without loss of stability for up to 96 hours. CONCLUSION: Solutions of chlorothiazide (10 mg/mL) and furosemide (1 mg/mL) stored either separately or together in polypropylene syringes remained stable for up to 96 hours at room temperature and protected from light.

Simultaneous determination of hydrochlorothiazide and benazepril hydrochloride or amiloride hydrochloride in presence of hydrochlorothiazide impurities: chlorothiazide and salamide by HPTLC method.

Simple, selective and sensitive high-performance thin layer chromatographic (HPTLC) method has been developed and validated for the simultaneous determination of hydrochlorothiazide (HCZ) in the presence of its impurities (chlorothiazide (CT) and salamide (DSA)), in two quaternary mixtures with benazepril hydrochloride (BZ) or amiloride hydrochloride (AM). The separation was carried out on HPTLC silica gel 60 F254 using ethyl acetate-methanol-glacial acetic acid (85:2:0.3 v/v/v) followed by densitometric measurement of bands at 240 nm for the first mixture containing HCZ, CT, DSA, BZ and by using ethyl acetate-methanol-water-ammonia (90:10:5:3 v/v/v) followed by densitometric measurement at 278 nm for the second mixture containing HCZ, CT, DSA, AM. Calibration curves were constructed in the range of (0.2-1.8 µg/band) and (0.4-2.2 µg/band) with good accuracy for HCZ and BZ, respectively, for the first mixture and in the range of (0.6-1.8 µg/band) and (0.4-2.4 µg/band) with good accuracy for HCZ and AM, respectively, for the second mixture. The developed method was validated according to ICH guidelines and demonstrated good accuracy and precision. Moreover, the methods were successfully applied for the determination of HCZ and BZ and AM in pure form and pharmaceutical dosage forms. The results were statically compared with the reported methods with no significant difference, indicating the ability of the proposed method to be used for routine analysis of drug product.

Linear support vector regression and partial least squares chemometric models for determination of Hydrochlorothiazide and Benazepril hydrochloride in presence of related impurities: a comparative study.

Partial least squares regression (PLSR) and support vector regression (SVR) are two popular chemometric models that are being subjected to a comparative study in the presented work. The comparison shows their characteristics via applying them to analyze Hydrochlorothiazide (HCZ) and Benazepril hydrochloride (BZ) in presence of HCZ impurities; Chlorothiazide (CT) and Salamide (DSA) as a case study. The analysis results prove to be valid for analysis of the two active ingredients in raw materials and pharmaceutical dosage form through handling UV spectral data in range (220-350 nm). For proper analysis a 4 factor 4 level experimental design was established resulting in a training set consisting of 16 mixtures containing different ratios of interfering species. An independent test set consisting of 8 mixtures was used to validate the prediction ability of the suggested models. The results presented indicate the ability of mentioned multivariate calibration models to analyze HCZ and BZ in presence of HCZ impurities CT and DSA with high selectivity and accuracy of mean percentage recoveries of (101.01±0.80) and (100.01±0.87) for HCZ and BZ respectively using PLSR model and of (99.78±0.80) and (99.85±1.08) for HCZ and BZ respectively using SVR model. The analysis results of the dosage form were statistically compared to the reference HPLC method with no significant differences regarding accuracy and precision. SVR model gives more accurate results compared to PLSR model and show high generalization ability, however, PLSR still keeps the advantage of being fast to optimize and implement.

Multi-residue analytical method for human pharmaceuticals and synthetic hormones in river water and sewage effluents by solid-phase extraction and liquid chromatography-tandem mass spectrometry.

Pollutants such as human pharmaceuticals and synthetic hormones that are not covered by environmental legislation have increasingly become important emerging aquatic contaminants. This paper reports the development of a sensitive and selective multi-residue method for simultaneous determination and quantification of 23 pharmaceuticals and synthetic hormones from different therapeutic classes in water samples. Target pharmaceuticals include anti-diabetic, antihypertensive, hypolipidemic agents, ß2-adrenergic receptor agonist, antihistamine, analgesic and sex hormones. The developed method is based on solid phase extraction (SPE) followed by instrumental analysis using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) with 30 min total run time. River water samples (150 mL) and (sewage treatment plant) STP effluents (100 mL) adjusted to pH 2, were loaded into MCX (3 cm(3), 60 mg) cartridge and eluted with four different reagents for maximum recovery. Quantification was achieved by using eight isotopically labeled internal standards (I.S.) that effectively correct for losses during sample preparation and matrix effects during LC-ESI-MS/MS analysis. Good recoveries higher than 70% were obtained for most of target analytes in all matrices. Method detection limit (MDL) ranged from 0.2 to 281 ng/L. The developed method was applied to determine the levels of target analytes in various samples, including river water and STP effluents. Among the tested emerging pollutants, chlorothiazide was found at the highest level, with concentrations reaching up to 865 ng/L in STP effluent, and 182 ng/L in river water.

Determination of reserpine and chlorothiazide in commercial tablets by liquid chromatography with fluorescence and UV absorbance detectors in series.

A procedure is presented for determination of reserpine and chlorothiazide in commercial tablets by liquid chromatography (LC). Powdered sample, equivalent to the weight of one tablet, is dissolved in 10.0 mL dimethyl sulfoxide, the mixture is diluted to 100.0 mL with methanol, and the solution is filtered; 10 mL of the filtrate is then diluted to 100.0 mL with methanol. The standard solution is prepared in the same solvent mixture and contains the 2 ingredients in approximately the same quantities as in the diluted sample solution. For LC, a 7.5 cm long normal-phase column is used; mobile phase consists of methanol containing a small volume of an aqueous solution of 1-pentanesulfonic acid, sodium salt. Two detectors are arranged in series: a fluorescence detector set at 280 nm excitation and 360 nm emission quantitates reserpine and a UV absorbance detector set at 300 nm determines chlorothiazide. Several synthetic mixtures containing the 2 ingredients in amounts ranging from 80 to 120% of quantities declared in commercial tablets were analyzed by the proposed method. Two samples of commercial tablets were also analyzed; for each sample, 5 determinations were made on a ground composite of 20 tablets; 10 individual tablets were also analyzed. The composites were also analyzed by the current U.S. Pharmacopeia method for this product.

First-derivative UV spectrophotometric and high-performance liquid chromatographic analysis of some thiazide diuretics in the presence of their photodecomposition products.

Ethanolic solutions of three thiazide diuretics, chlorothiazide, hydrochlorothiazide and trichlormethiazide, were irradiated with a high-pressure mercury lamp. The products were isolated and their first-derivative UV spectra in ethanol were recorded and compared to those of the parent compounds. The determination of the parent compounds in the presence of the decomposition products was carried out at wavelengths near 220 nm using the zero-crossing technique. Three reversed-phase HPLC methods were also developed for the analysis of the parent compounds. In parallel analyses of the reaction mixtures a good correlation was achieved between these two methods in the determination of hydrochlorothiazide and trichlormethiazide while there was greater variation in the results of chlorothiazide.

Validated micellar electrokinetic capillary chromatography method for quality control of the drug substances hydrochlorothiazide and chlorothiazide.

A stability-indicating, quality control analysis method was developed and validated for the diuretic drug substances hydrochlorothiazide (HCTZ) and chlorothiazide (CTZ). Micellar electrokinetic capillary chromatography employing the anionic detergent sodium dodecyl sulfate at 30 mM in 20 mM sodium borate buffer pH 9.5 was utilized to separate and quantify the active drug substance HCTZ from CTZ and the common impurity, 4-amino-6-chloro-1,3-benzenedisulfonamide (DSA). A 100 microns I.D. uncoated fused-silica capillary was necessary to provide the sensitivity, i.e. 1 microgram/ml, for quantification of the DSA impurity. In this study, the linearity, precision, selectivity, accuracy, reproducibility and limit of quantitation for the method were investigated for HCTZ, CTZ and DSA. As the first validation of a drug substance method by capillary electrophoresis in this laboratory, unusual care was taken to insure reliability and ruggedness with multiple instruments, capillaries and analysts. Precision and reproducibility in the range of 1% R.S.D. was achieved by controlling subtle injection factors. These included minimizing the time in which the capillary ends were not immersed in buffer or sample during the injection process and minimizing the number of assays for each anode or inlet buffer vial. Stacking induced by differences in ionic strength between sample and capillary buffer was reduced by using a sample buffer concentration similar to that of the capillary buffer. Although stacking accomplished by using lower sample buffer concentrations increased sensitivity, reproducibility was decreased. Achievement of the 1% R.S.D. precision level means that many quality control assays for drugs with good absorbance characteristics can be validated with HPLC reproducibility and CE efficiency. These micellar electrokinetic capillary chromatography methods conform to the USA and European Pharmacopoeial validation guidelines.

Effect of temperature and fat content on the solubility of hydrochlorothiazide and chlorothiazide in milk.

The solubility of hydrochlorothiazide and chlorothiazide in milk has been studied. Experiments were carried out at 5, 15, 25, and 37 degrees C on a buffer solution of pH 6.5, a 2.6% solution of casein, bovine skim milk samples, and bovine milk samples with fat contents of 0.75, 1.70, and 3.50%. The "total" solubility of both drugs in the media studied was higher than the buffer solubility. The highest "total" solubility for both drugs was observed in skim milk. Based on binding data of thiazides to milk, the "total" solubility was split into "free" and "bound" solubility. The increases of solubility noted cannot be explained on the basis of drug-milk binding data. The enhancement of solubility was attributed to the increase of intrinsic solubility of drugs in milk. Results of the thermodynamic analysis of solubility data showed that a different solubilization process of hydrochlorothiazide may be responsible for the high solubility values found in skim milk for this drug. In contrast, the thermodynamic parameters of chlorothiazide in all types of milk are similar, indicating a common solubilization mechanism. The biopharmaceutical significance of the findings is discussed in light of the freeze-dried drug-milk formulations and coadministration of drugs with milk in general.

Liquid chromatographic determination of methyldopa and methyldopa-thiazide combinations in tablets: collaborative study.

A reverse phase liquid chromatographic method for the determination of methyldopa, methyldopa-hydrochlorothiazide, and methyldopachlorothiazide in tablets was collaboratively studied by 8 laboratories. Each collaborator received 20 samples that included drug substance, synthetic and commercial tablet compositions. The overall repeatability and reproducibility standard deviations for commercial tablets were 1.11 and 1.75% for methyldopa, 0.96 and 1.62% for chlorothiazide, and 1.21 and 2.15% for hydrochlorothiazide, respectively. The overall recoveries of methyldopa, chlorothiazide, and hydrochlorothiazide added to synthetic tablets were 100.78, 100.70, and 101.34%, respectively. The method has been adopted official first action.

High-pressure liquid chromatographic determination of chlorothiazide and hydrochlorothiazide in plasma and urine: preliminary results of clinical studies.

High-pressure liquid chromatographic procedures were developed for the determination of chlorothiazide and hydrochlorothiazide in plasma and urine. The plasma assay incorporates a preextraction procedure that eliminates interference by endogenous substances. Chromatography is carried out on an octadecyl reversed-phase column. Mobile phases are 15% methanol in 0.01 M acetic acid for plasma and 4% acetonitrile in 0.01 M sodium perchlorate, adjusted to pH 4.6, for urine. At a flow rate of 2.5 ml/min, the retention times for chlorothiazide and hydrochlorothiazide are 3.5 and 4.6 min for plasma and 10.5 and 13.5 min for urine, respectively. Preliminary results of a clinical study in fasting male volunteers showed that the plasma levels and urinary excretion rate of chlorothiazide peaked at 1-2 hr following a 500-mg oral dose and subsequently declined irregularly. On the other hand, the plasma levels and urinary excretion rate of hydrochlorothiazide peaked at 2-3 hr following a 50-mg oral dose and subsequently declined in biphasic fashion. Urinary excretion rates of both chlorothiazide and hydrochlorothiazide closely resemble their concentration profiles in plasma.

Drugs in breast milk.

PIP: Data on the pharmacology of drugs in breast milk are incomplete. The concentration in milk of drugs present in maternal blood depends on the lipid solubility of the drug and its degree of ionization. The immature renal and hepatic functions in the nursing infant can delay excretion of drugs. There has been no documented harm to nursing infants due to maternal use of oral contraceptives although long-term studies are unavailalbe. Breast feeding is contraindicated if the mother uses therapeutic doses of radioactive iodine, is a severe chronic alcoholic, or takes corticosteroids, phenobarbitone, and anticancer drugs. During lactation, drugs should be avoided as much as possible.^ieng