DEVELOPMENT AND VALIDATION OF RAPID STABILITY INDICATING HPLC-DETERMINATIONS OF ANTIEPILEPTIC DRUGS PHENOBARBITAL IN SUPPOSITORIES AND PHENYTOIN IN CAPSULES AS WELL AS IN URINE SAMPLE

Abstract

Two simple, rapid, accurate, and stability indicating HPLC methods are described for quantitation of Phenobarbital and Phenytoin in bulk powders, dosage forms, or urine. Chromatographic quantitation of Phenobarbital was developed on Chromolith® Performance RP-18e column, using isocratic binary mobile phase of MeOH and H2O (38: 62, V/V) at flow rate of 3 mLmin−1. Determination of Phenytoin was achieved using a conventional RP C-18, applying isocratic binary mobile phase of ACN and H2O (25: 75, V/V) at flow rate of 1 mL min−1. The elution times of Phenobarbital and Phenytoin are 1.397 ± 0.039 and 5.604 ± 0.013 min, respectively. Each method was validated for system suitability, linearity, precision, limits of detection and quantitation, specificity, stability, and robustness. Stability tests were done through exposure of the analyte solutions to four different stress conditions: reflux with 1 N HCl, reflux with 1 N NaOH, reflux with 30% H2O2, and exposure to UV radiation. Limits of detection and quantitation were 0.125 and 0.250 µgmL−1 as well as 0.250 and 0.500 µgmL−1 for Phenobarbital and Phenytoin, respectively. Due to the short separation time of Phenobarbital, the method was applied for dissolution study in presence of beta-cyclodextrin. The proposed methods can be used for routine samples or stability studies.