[Effects of temperature and PH on dissolution kinetics of methotrexate in aqueous media].

In vitro dissolution kinetics of Methotrexate have been analysed at different temperatures in water at pH 1.5. After giving rise to the dissolution reaction, it has been possible to follow up the kinetic of dissolution and calculate energy activation. The pH variation allows us also to appreciate the constant behaviour of dissolution at temperature 310 K (37 degrees). Weilbull equation is valid with success for dissolution reaction as well during temperature variation and different values of pH. In both cases the Weibull constant b has been calculated and compared to constant dissolution K.