Pharmaceutical products in sustained-release form, and their preparation process.

摘要

A new sustained-release form is described for the oral administration of drugs which produce a pH value of less than or equal to 5 when in aqueous solution. The new sustained-release form can also be used for drugs which do not produce an acid pH when in solution but which can be formulated with excipients of acid pH. The formulation comprises essentially: a) a nucleus constituted by a continuous rigid polymer matrix which incorporates the drug, this polymer matrix being insoluble at acid pH values but biodegradable at pH values exceeding 5. b) a first film which is applied over the nucleus and is arranged to regulate the diffusion of the drug by means of a membrane effect; c) a second film which does not obstruct the diffusion the drug, which protects the preceding film and which possibly carries a quantity of drug to compensate for the release time lag.