Two simple and sensitive indirect spectrophotometric methods for the assay of propranolol hydrochloride (PPH) and piroxicam (PX) in pure and pharmaceutical formulations have been proposed. The methods are based on the oxidation of PPH by a known excess of standard N-bromosuccinimide (NBS) and PX by ceric ammonium sulfate (CAS) in an acidic medium followed by the reaction of excess oxidant with promethazine hydrochloride (PMH) and methdilazine hydrochloride (MDH) to yield red-colored products. The absorbance values decreased linearly with increasing concentration of the drugs. The systems obeyed Beer's law over the concentration ranges of 0.5 -12.5 and 0.3 -16.0 µg/ml for PPH, and 0.4 -7.5 and 0.2 -10 µg/ml for PX with PMH and MDH, respectively. Molar absorptivity values, as calculated from Beer's law data, were found to be 1.36 × 10 4 and 2.55 × 10 4 l mol -1 cm -1 for PPH, and 2.08 × 10 4 and 2.05 × 10 4 l mol -1 cm -1 for PX with PMH and MDH, respectively. The common excipients and additives did not interfere with their determinations. The proposed methods have been successfully applied to the determinations of PPH and PX in various dosage forms. The results obtained by the proposed methods compare favorably with those of official methods.
Pyridine-4-carboxilic acid hydrazide, commercially known as isoniazid (INH), is an antitubercular drug and is now widely used together with rifampicin and streptomycin for the chemotherapy of tuberculosis. This has prompted many researchers to develop accurate and rapid methods for the determination of INH in pure and pharmaceutical formulations. Of the various techniques used for the determination of this drug, FIA-spectrofluorometry, 1,2 polarography 3 and adsorptive stripping voltammetry 4 are of high cost and are not available at most quality-control laboratories. Other methods include highperformance liquid chromatography 5 and indirect potentiometric titration.
6Many spectrophotometric methods have been described for the assay of INH in pharmaceutical preparations; some of these are either time bound, 7-9 involve extraction, 10 require heating, 11,12 need cooling to lower the temperature for a long time 13 or are less sensitive. 11,14 The United States Pharmacopoeia (USP) method 15 involves a titration procedure, which is both laborious and time consuming. Hence, it was planned to develop a reasonably sensitive and economically viable technique, like a spectrophotometric procedure.In the present paper, we report on a rapid and sensitive spectrophotometric method for the determination of INH in pure and pharmaceutical formulations based on the oxidation of 4,5-dihydroxy-1,3-benzenedisulfonic acid (Tiron) by sodium metaperiodate (SPI) followed by oxidative coupling with INH in an alkaline medium.
Experimental
ApparatusA Hitachi UV-visible spectrophotometer Model U-2001 with 1-cm matched quartz cells was used for all absorbance measurements.
Reagents and samplesAll of the chemicals used were of either pharmaceutical or analytical grade. Quartz-processed high-purity distilled water was used throughout. A standard solution of INH was prepared by dissolving a requisite amount of INH in distilled water. It was diluted as and when required. A 0.5% solution of each of SPI and tiron and a 0.1 M NaOH solution were prepared separately in distilled water.
Determination of pure drugAliquots of standard solutions of INH were transferred into a series of 10 ml calibrated flasks. To each of these were added 0.25 ml of SPI, 0.5 ml tiron and 1.25 ml of NaOH and diluted to the mark with distilled water. The absorbances of the redcolored product were determined at 507 nm against a reagent blank. Calibration graph was constructed or the regression equation calculated.
Analysis of pharmaceutical formulationsTwenty tablets of INH were weighed, finely powdered and an amount equivalent to 50 mg of INH was dissolved in water and filtered. The filtrate was made up to 100 ml and a suitable amount of an aliquot was treated as described above for a pure sample.For the syrup, an appropriate volume of the sample was taken and analyzed for INH using the procedure described for a pure sample.
Results and DiscussionTiron readily undergoes oxidation by SPI, which further couples with INH in the presence of sodium hydroxide to form an intense ...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.