Discrepancy among dissolution rates of commercial tablets as a function of dissolution method. Part 5: In vitro/in...

The bioavailability of seven commercially available batches of chlorpromazine hydrochloride tablets belonging to three different brands was assessed by measuring the intensity of miotic response to the tablets in six normal human subjects according to a cross-over design system. The following pharmacodynamic parameters were computed, viz., maximum miotic response intensity, tmax, half-peak time as well as the area under the percentage miotic response intensity versus time curve from time 0 to 8 h. Attempts to correlate two in vitro dissolution parameters, that is, dissolution efficiency and percentage weight of drug dissolved after 30 min to the in vivo parameter of the area under percentage miotic response intensity versus time curve revealed that the second in vitro parameter correlates better than the first one with the in vivo parameter regardless of the dissolution method. On the other hand, the two in vitro dissolution parameters obtained by the USP rotating basket method show good correlation with the in vivo parameter.