Experimental design approach to optimize stability indicating LC method for the determination of Naftopidil in its bulk and tablet dosage form

A new stability indicating reverse phase high performance liquid chromatography (RP-HPLC) method for analysis of Naftopidil (NAF), both as a bulk drug and in formulation, was developed and validated. The separation was achieved using a C ₁₈ GRACE column (250 mm × 4.6 mm i.d., 5 μm particle size) and gradient mobile phase system consisting of (A) 10mM of ammonium acetate buffer pH adjusted to 4.0 with glacial acetic acid and (B) acetonitrile. The fl ow rate was 1.0 mL/min with UV detection at 284 nm. NAF was subjected to stress conditions like hydrolysis (acid, alkali and neutral degradation), oxidation, photolytic and thermal decomposition. The linearity of the proposed method was investigated in the range of 10–150 μg/mL. Application of design of experiments for the robustness study method was carried out, where in fi ve factors were selected: pH of mobile phase, fl ow rate, strength of the buffer and column temperature. These factors were examined using [email protected] (SAS Institute) software.

Key words: RP-HPLC ; Forced degradation studies ; Naftopidil ; Design of experiments