Validated Stability – Indicating Methods for Determination of Oseltamivir Phosphate

Aims: Two simple and sensitive stability- indicating methods were developed and validated for the quantitative determination of oseltamivir phosphate in presence of its degradation product.

Place and Duration of Study: Analytical Chemistry Department, Faculty of Pharmacy (Girls), Al-Azhar University, between January 2016 and Augest 2016.

Methodology: The first method depends on densitomeric determination of thin layer chromatograms of the drug using a mobile phase of methanol – toluene – ammonia (8: 10: 2, v/v/v). The second method was UPLC method, in which efficient separation was carried out on phenomenex kinetex 2.6 μm C18100 A column using a mobile phase consisting of 85% potassium hydrogen phosphate - methanol (80:20, v/v), adjusted to pH 3.5 with orthophosphoric acid at a flow rate of 1 mL min-1 and UV detection at 207 nm.

Results: Beer’ law was obeyed in the range of 1-15 mg/spot and 6-14 μg mL–1 of the drug using the two procedures, respectively.

Conclusion: The proposed methods were successfully applied for the determination of oseltamivir phosphate in bulk powder, laboratory prepared mixtures and pharmaceutical dosage form with good accuracy and precision. The methods were validated according to ICH guidelines. The results obtained were compared with those of the reported method and were found to be in good agreement.