Two Simple, fast and reliable derivative spectrophotometric methods were developed for determination of efavirenz in bulk and pharmaceutical dosage forms. The solutions of standard and the sample were prepared in methanol. The quantitative determination of the drug was carried out using the zero order derivative values measured at 239 nm and the first order derivative values measured at 248 nm. Calibration graphs constructed at their wavelengths of determination were linear in the concentration range of efavirenz using 5-40 μg.mL-1 (r² = 0.9997 and r² = 0.9998) for zero order and first order derivative spectrophotometric method. All the proposed methods have been extensively validated as per ICH guidelines. There was no significant difference between the performance of the proposed methods regarding the mean values and standard deviations. These methods were successfully applied to pharmaceutical formulations because no interferences from tablet excipients were found. The proposed methods were found to be simple, sensitive, accurate, precise, rapid and economical for the routine quality control application of efavirenz in pharmaceutical formulations.
