A system for controlled release of an active principle, includes at least (a) a degradable polymer matrix which produces acid compounds and (b) at least one acid-sensitive complex of an active principle having at least one electrostatic charge and a complexing polyelectrolyte partner of opposite charge which complexes with the active principle. A method for preparation of such a system is described. The release of the active principle (7P) is prolonged over 18 days (ternary system PMLA/7P/PLAGA) in comparison to binary systems (7P/PLAGA) and (PMLA/7P).
