Medicaments in sustained release unit dose form

Claim 1

A sustained release pharmaceutical composition for oral administration containing, as the active ingredient, a medicament of the formula: ##STR2## where R is lower-alkyl having from 1 to 4 carbon atoms which comprises a plurality of beads each composed of an inert particulate core having adhered thereto a coating comprising particles of said medicament and further coated with a sustaining coating comprising three admixed polymers, the first said polymer being soluble at all pH values of 1.5 and above, the second said polymer being insoluble in gastric juices at pH values below about 5 but soluble therein at pH values of about 5 and above and the third said polymer being insoluble in the contents of the gastrointestinal tract at all pH values normally encountered therein, and wherein the ratio of the weight of the third polymer to the combined weight of the other two polymers is about 1.5:1 to about 2:1.