An alternative method to the evaluation of similarity factor in dissolution testing.

This paper addresses an alternative method to the evaluation of similarity factor f(2) as a criterion for assessment of similarity between two in-vitro dissolution profiles as proposed in the SUPAC-IR Guidance (1995). Diltiazem hydrochloride Sustained-Release (SR) tablets were tested and the following independent-model dissolution parameters were used: t10% dissolution time, t25% dissolution time, t50% dissolution time, mean dissolution time (MDT), dissolution efficiency (DE) at t(120), and at t(360). To compare the dissolution profiles, several release models were tested such as Higuchi, zero order, first order, Baker-Lonsdale, Hixson-Crowell, Weibull and Korsmeyer-Peppas. The similarities between two in-vitro dissolution profiles were assessed by pair-wise independent-model procedures such as difference factor (f1), similarity factor (f2) and Rescigno index (xi1 and xi2). The in vitro release kinetics of diltiazem hydrochloride sustained release tablets were evaluated using USP apparatus 2.