Simultaneous determination of bisoprolol Fumarate and hydrochlorothiazide in tablets by derivative spectrophotometry and densitometry

Derivative spectrophotometry [second and fourth] and densitometry were used to determine bisoprolol fumarate [I] and hydrochlorothiazide [II] simultaneously in combined pharmaceutical dosage form. Using second derivative spectrophotometry, the amplitudes in the second derivative spectra at 272.6nm and 284.8nm were selected for simultaneous determination of [I] and [II], respectively, in the mixture. Where, the HZ concentration was calculated from the amplitude at 284.8 nm [where BSF showed no absorbance] and BSF concentration was calculated from the amplitude at 272.6 nm after subtraction of the amplitude due to HZ. While, applying fourth-derivative spectrophotometry technique, the peak amplitudes at 289.8 nm and 272.8 nm were selected to determine [I] and [II], respectively. The calibration graphs were linear in the range of 30-280 microg/ml for [I] and 3-24 microg/ml for [II] in both methods. Furthermore, a densitometric procedure with ultraviolet detection at 223nm was applied using chloroform: ethanol: Glacial acetic acid [7:3:2 by volume] as a developing system. The plot of peak area of [I] and [II] to the respective concentrations of each drug was found to be linear in the range of 2.5-30micro g/spot and 1-7 micro g/spot, respectively. The suggested methods were used to determine both compounds in synthetic mixtures and in commerical tablets. The validity of the proposed methods was further assessed by applying standard addition technique. The obtained results were statistically compared with compandial HPLC method, showing no significant difference with respect to accuracy and precision

Spectrophotometric determination of aminoglutethimide in pure form, in its tablets and in plasma

Simple, rapid and accurate spectrophotometric method for the assay of aminoglutethimide [AG] was described. This method is based on the formation of a highly colored stable radical anion complex between the drug as an n-electron donor and chloranilic acid [CLA] as a p-electron acceptor. The spectra of the complex showed a maximum absorbance at about 728 nm. Beer's law was obeyed in the concentration range of 0.15-0.5 mg ml-1. The proposed method was applied successfully for the determination of aminoglutethimide in pure form, in its tablets and in plasma. The results were favorably comparable to the official method

Spectrophotometric determination of cimetidine in dosage forms using chloranilic acid

A simple, rapid and sensitive spectrophotometric procedure is described for the determination of cimetidine either in pure form or in pharmaceutical formulations. The method is based on the reaction of cimetidine as an electron donor with chloranilic acid as a pie electron acceptor. The charge transfer complex formed has a purple colour with a maximum absorbance at about 530 nm. The calibration graph was linear over the range of 25-200 [micro] g/ml. The method was applied to cimetidine in pharmaceutical formulations giving accurate, precise and reproducible results. Comparing these results with those obtained using the British Pharmacopeal method, and with one of the compendial colourimetric methods, there is no significant difference between the performance of the three methods using the Student's t-test and the variance ratio F-test. In addition the proposed method is more simple and rapid

Stability indicating permanganometric procedure for the determination of doxycycline hydrochloride

A permanganometric method for the quantitative determination of the intact doxycycline hydrochloride is described. The method depends upon the preliminary TLC separation of 1-14 mg of doxycycline hydrochloride on silica gel-H glass plates, using n-butanol, NH4OH, water [5: 1: 5] as a developing solvent. The spot corresponding to the intact molecule parallel to that of a reference sample is identified under U.V. lamp, scratched extracted with water, treated with 25% H2SO4 heated to 60-70C and titrated with 0.05 N KMnO4. The concentration of doxycycline hydrochloride is computed from a standard calibration curve, or from the equivalence factor calculated to be 0.542 mg doxycycline hydrochloride for each milliliter of 0.05 N KMnO4. The efficiency of the method is assessed by mixing a reference sample of doxycycline hydrochloride with controlled, alkaline degraded samples, and the results obtained are found to concord nicely. The method is applied to doxycycline hydrochloride bulk power and to its capsule pharmaceutical formulation