Abstract: The invention concerns a pharmaceutical composition in gelatine capsule form, comprising (a) an active core composition comprising at least one pharmaceutically active compound and optionally conventional pharmaceutical adjuvants, (b) at least one quenching protective layer, positioned between said active core composition and the inner surface of the gelatine capsule shell, which comprises at least one quenching agent, the quenching agent being able to chemically bind volatile impurities initiating the cross-linking of gelatine by a substantially irreversible chemical reaction after said impurities have been released by either adjuvants and/or active compound(s) of said active core composition and (c) a gelatine capsule shell wrapping said active core composition including any adjuvant material and any quenching layer added to the active core composition. Such a composition has improved stability on storage.

Abstract: The instant invention is a tilidine salt, tilidine dihydrogen orthophosphate, which owing to its surprising stability, is particularly suitable for use in the preparation of solid, in particular delayed-action, drugs in tablet, pill or capsule form.