Simultaneous estimation of montelukast sodium and d esloratadine by ratio spectra derivative spectrophotometry method in comb ined dosage forms

Montelukast sodium is a leukotriene receptor antago nist, used in the treatment of asthma and Deslorata dine is a drug used to treat allergies The combination formul ation is used for the treatment of allergic rhiniti s. The Ratio spectra derivative spectrophotometric method was de veloped for the simultaneous determination of Monte lukast sodium (MTKT) and Desloratadine (DESLO) in combined dosage forms. The method depends on the use of the first derivative of the ratio-spectra obtained by dividin g the absorption spectrum of binary mixtures by a s tandard spectrum of one of the compounds. The first derivat ive amplitudes at 218.6 and 262 nm were selected fo r the determination of MTKT and DESLO respectively. The w avelength interval (Dl) was selected as 8 nm. Metha nol was used as the solvent. Both the drugs showed linearit y in the range of 5-40μg/ml. The method was validat e statistically and recovery studies were carried out . It was found to be accurate, precise and reproduc ible. The method was applied to the assay of the drugs in mar keted formulation, which were found in the range of 99.47% to 101.25% of the labeled value for both Montelukast s odium and Desloratadine. Hence, the method here in described can be successfully applied in quality control of c mbined pharmaceutical dosage forms.