Stability-indicating RP- HPLC -DAD method for the simultaneous estimation of Tramadol HCl and Diclofenac sodium

A Specific stability-indicating high performance liquid chromatographic method was developed and validated for the determination of Tramadol HCl and Diclofenac sodium in a tablet dosage form. The separation was achieved on a reverse phase C18 column (Agilent ODS) (250 × 4.6 mm, 5 µ m) with mobile phase consisted of methanol:water (61:39 % v/v containing 0.2 % HSA, pH 3.0 adjusted with Orthophosphoric acid) and the eluents were detected at 219 nm. The retention time of Tramadol HCl and Diclofenac sodium was 5.9 min and 26.30 min respectively with the flow rate of 1ml/min. Drugs were subjected to stress conditions of acidic, basic, oxidation, photolytic, neutral and thermal degradation, considerable degradants were detected in all stress conditions. The method resulted in detection of 17 degradation products (D1 – D17), among those products, structures of D2, D9, D10, D12, D14, D15 and D16 were identified. The response of linear was in the range 5-50 µg/ml for Tramadol HCl and 10 to 70 µg/ml for Diclofenac sodium, respectively. Intra day precision was the range of 0.83-1.34(% RSD) for Tramadol and 0.27-0.93(% RSD) for Diclofenac. Inter day precision was the range of 1.33-1.81(% RSD) for Tramadol and 0.96-1.32(% RSD) for Diclofenac. Recoveries ranged in between 98-102 %.