Extractive Spectrophotometric Methods for the Determination of Oxomemazine Hydrochloride in Bulk and Pharmaceutical Formulations Using Bromocresol Green, Bromocresol Purple and Bromophenol Blue

Enantiomeric separation of oxomemazine in rabbit plasma by ultra-fast LC and application in a stereoselective pharmacokinetic study

Aim: Ultra-fast LC was used to establish a new bioanalytical method for enantiomeric separation of oxomemazine. Methods: The proposed study was carried out using the ultra-fast LC technique with an amylose chiral column. The bioanalytical approach was used in rabbit plasma following US FDA regulations and then extended to oxomemazine enantiomeric separation using metronidazole as the internal standard. Results: The retention times of (R)-oxomemazine, (S)-oxomemazine and the internal standard were found to be 9.511, 10.712 and 6.503 min, respectively. Within-run and between-run precision (percent relative standard deviation) was found to be in the range of 0.018-0.102% for (R)-oxomemazine and 0.028-0.675% for (S)-oxomemazine, whereas accuracy (%) was found to be in the range of 95.971-99.720% for (R)-oxomemazine and 97.199-103.921% for (S)-oxomemazine. Conclusion: The findings revealed that stereospecific distribution of oxomemazine enantiomers does not change significantly.

Spectrophotometric Determination of Thioridazine Hydrochloride in Tablets and Biological Fluids by Ion-Pair and Oxidation Reactions

Two simple, sensitive and selective spectrophotometric methods have been described for the determination of the psychoactive drug, thioridazine HCl in tablets and in biological fluids. The first method is based on the oxidation of thioridazine HCl with measured excess of KMnO4under acidic conditions followed by the determination of unreacted oxidant using indigo carmine and methyl orange. The second method is based on the formation of ion-pair complexes with the acidic sulphophthalein dyes such as bromocresol green and bromocresol purple at pH 1.8 of KCl-HCl buffer. The formed complexes were extracted into methylene chloride and their absorbance was measured at 412 nm. Optimizations of the different experimental conditions are described for both methods. The proposed methods were successfully applied for determination of the drug in tablets and biological fluids with good accuracy and precision. Statistical comparison of the results with those obtained by an official method showed good agreement and indicated no significant difference in accuracy and precision.

Spectrophotometric determination of benzydamine HCl, levamisole HCl and mebeverine HCl through ion-pair complex formation with methyl orange

A simple, rapid and sensitive spectrophotometric method has been proposed for the assay of benzydamine HCl (BENZ), levamisole HCl (LEV) and mebeverine HCl (MBV) in bulk and pharmaceutical formulations. The method based on the reaction of the selected drugs with methyl orange (MO) in buffered aqueous solution at pH 3.6. The formed yellow ion-pair complexes were extracted with dichloromethane and measured quantitatively with maximum absorption at 422 nm. The analytical parameters and their effects on the reported systems are investigated. The extracts are intensely colored and very stable at room temperature. The calibration graphs were linear over the concentration range of 2-10 microg ml(-1) for BENZ, 6-24 microg ml(-1) for LEV and 4-14 microg ml(-1) for MBV. The stoichiometry of the reaction was found to be 1:1 in all cases and the conditional stability constant (K(f)) of the complexes have been calculated. The proposed method was successfully extended to pharmaceutical preparations-tablets. Excipients used as additive in commercial formulations did not interfere in the analysis. The proposed method can be recommended for quality control and routine analysis where time, cost effectiveness and high specificity of analytical technique are of great importance.