[Comparative studies on the in vitro dissolution and bioavailability of various acetylsalicylic acid preparations]

For five different brands of acetylsalicylic acid (ASA) preparations the in vitro/in vivo data were determined and tested for comparability. The in vitro dissolution rates were determined by two different methods (Paddle, rotating basket) whereas the in vivo data were obtained from 15 volunteers in a 5-fold cross-over trial. The markedly worse in vitro dissolution (rotating basket) of one preparation is in contrast to the in vivo data which showed bioequivalency of all five preparations. It is doubled that in vitro measurements alone reveal sufficient informations for any predictions of the in vivo characteristics (e.g. bioavailability) of a preparation. It was possible to determine separately ASA and salicylic acid using a highly selective HPLC-method developed by us.