Development of RP-HPLC HPTLC and UV-Visible Spectrophotometry Methods

Six methods RP-HPLC RP-HPTLC/densitometry and UV-Spectrophotometry (first order amplitude first order AUC second-order amplitude and second order AUC) have been developed for the determination of tadalafil in bulk and pharmaceutical formulation. RP-HPLC and RP-HPTLC/Densitometry methods are found to be accurate precise rugged and robust. Both these methods are adequately sensitive. The only limitation of RP-HPLC and RP-HPTLC/densitometry method is their cost. For RP-HPLC study Design Expert software ver. 8.0.4 was used to study robustness parameter which showed that method is robust. From results of ANOVA and analysis of response surfaces plots; it can be concluded that responses y1 (Retention time) and y2 (Tailing factor) are robust for x1 x2 and x3; however for y3(Theoretical plates) x1 x2 and x3 affect considerably. All four UV-Spectrophotometric methods are simple accurate precise and least calculations are involved for estimation of concentrations of the drug. No interference of the excipients was observed in any one of the methods during tablet assay. All the developed methods can be used for routine analysis of tadalafil in the pharmaceutical formulation.