A Comparison of in vivo and in vitro Methods of Studying the Release Rate of Drug into the Gastaointestinal Tract in Man Exemplified by Sustainid Release Formulations of Phendimetrazine

Abstract

An analogue computer system was used to simulae a model repre senting the metabolism and exerition of hendinatrasine and its mata-bolites, phensetrsine and phendi natraxina-N-oxide. This model was used in connation with an analogue computer program to compute the rate of release of phaendimetrasine into the gut lusan from three sus-tainad release formulation of phendiancraxina using data obtained by analysis of plasma. or urine. The dosage form availability profile so obtained was ooapared with In vitro dissolution test data.

The in vitro method was found to predict a. rate of release substantially greater than that found in vivo.