Vierodt's and Q-Absorption Ratio Spectrophotometric Methods for Simultaneous Determination of Drotaverine Hydrochloride and Paracetamol in Tablet Dosage Form

Two simple, accurate, precise, sensitive and economical spectrophotometric methods; Vierodt's method and Q Absorption ratio method have been described for the simultaneous estimation of drotaverine hydrochloride (DROT) and paracetamol (PCM) in combined tablet dosage form. Absorption maxima of drotaverine hydrochloride and paracetamol in 0.05 N NaOH was found to be 230.4 nm and 257 nm respectively. Drotaverine hydrochloride and Paracetamol obey Beer's law in the concentration range 2–80 μgmL-1 (r²=0.9996) and 2–30 μgmL-1 (r²=0.9997) in 0.05 N NaOH and mean recovery for drotaverine hydrochloride and paracetamol were found to be 100.75±0.74% and 100.27 ±0.70%, respectively. Q absorption ratio method employs 238.8 nm as λ1 (Isobestic point) and 257 nm as λ2 (λmax of Paracetamol) for formation of equations. Drotaverine hydrochloride and paracetamol obey Beer's law in the concentration range 2–80 μgmL-1 (r²=0.9993) and 2–30 μgmL-1 (r²=0.9997) in 0.05 N NaOH. The mean recovery for Drotaverine hydrochloride and Paracetamol were found to be 100.47 ± 0.10% and 100.006 ± 0.136%. The results of two methods were validated statistically and can be successfully applied for the routine analysis of drotaverine hydrochloride and paracetamol in bulk and combined tablet dosage form.