Three simple spectrophotometric methods have been described for the assay of olanzapine in its pure and pharmaceutical formulations. The direct method (A) is based on the drug oxidation with excess of N-bromosuccinimide in acidic medium and the two indirect methods (B and C) are based on the oxidation of the drug with excess of Nbromosuccinimide and cerium(IV)sulfate, followed by the reaction of the unconsumed oxidants with celestine blue. The calibration graphs were linear over the range 10 -120 μg mL -1 (method A), 0.5 -6.0 μg mL -1 (method B) and 0.6 -3.0 μg mL -1 (method C). After validation, the proposed methods were successfully applied to assay of olanzapine in its commercial tablets with mean percentage recoveries of 101.23 ± 0.10, 96 ± 0.10 and 94 ± 0.04%. The mechanism of olanzapine oxidation with N-bromosuccinimide was also proposed.

A simple spectrophotometric method for the determination of bezafibrate (BZF) is described. The procedure is based on the ternary complex formation between an investigated drug, palladium(II) ion, and eosin in buffered medium and in the presence of methyl cellulose as a surfactant. The composition of the compound, studied by spectrophotometric methods shows that the molar ratio BZF:Pd(II):eosin is 1:1:1. Optimal conditions for the reaction were established and the procedure was validated. The calibration graph was linear over the range 0.06-0.3 mg mL 21 , with relative standard deviation (RSD) 0.3%. The proposed method was successfully applied for the determination of bezafibrate in its pharmaceutical product with mean percentage recoveries of 99.74%.

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