Bromometric Estimation of Cefixime, Clarithromycin and Clindamycin in Bulk and Dosage forms

Two spectrophotometric methods are described for determination of Clarithromycin, Clindamycin and Cefixime in bulk and pharmaceutical dosage forms using insitu generated bromine as oxidizing agent and either methylene blue or methyl orange as chromogenic agents. Drugs are treated with known excess of bromine and residual unreacted bromine is determined by treating with fixed amount of either methylene blue or methyl orange then measuring absorbance at (666nm for clindamycin and cefixime or 678 nm for clarithromycin) and 510 nm respectively. The amount of bromine reacted corresponds to the amount of each drug. The effect's of acidity, bromate-bromide volume and time, on the absorption were studied. Calibration curves were linear over ranges of 3.2-16 μg.ml^-1 for Clarithromycin,1.6- 4.8 μg.ml^-1 for Clindamycin, 0.8-7.2 μg.ml^-1 for Cefixime in case of methylene blue and of 6.4-19.2 μg.ml^-1 for Clarithromycin, 0.8-4.0μg.ml^-1 for Clindamycin, 0.4-2 μg.ml^-1 for Cefixime in case of methyl orange. The methods were satisfactory applied for the determination of drugs in both bulk and pharmaceutical dosage forms and results were compared statistically with reference methods.