Development of an extended-release formulation of capecitabine making use of in vitro-in vivo correlation modelling.

An oral extended-release (ER) formulation of capecitabine was developed for twice daily dosing, theoretically providing a continuous exposure to capecitabine, thus avoiding the undesirable in-between dosing gap inherent to the dosing schedule of the marketed capecitabine immediate-release formulation (Xeloda((R))). The target 12-hour in vivo release profile was correlated to an in vitro dissolution profile using an in vitro-in vivo correlation model based on the pharmacokinetic (PK) and dissolution characteristics of Xeloda((R)). Making use of the slow dissolution characteristics of amorphous capecitabine as reported previously and screening of a panel of ER excipients, an ER formulation was designed. Kollidon((R)) SR induced the most prominent ER. Moreover, it was shown that tablets prepared from CoSD capecitabine and Kollidon((R)) SR have an additional threefold delay in dissolution compared with tablets prepared from the same but only physically mixed components. Therefore, a prototype tablet formulation composed of co-spray-dried capecitabine and Kollidon((R)) SR (98/2%, w/w) mixed with colloidal silicon dioxide (0.5%, w/w) and magnesium stearate (2.5%, w/w) was defined. This prototype shows similar dissolution characteristics as the modelled dissolution profile. Currently, the in vivo PK of our designed ER capecitabine formulations is investigated in a clinical study.