FOERFARANDE FOER FRAMSTAELLNING AV EN ORALT ADMINISTRERBAR FARMACEUTISK MULTIPELENHETSBEREDNING

A pharmaceutical oral controlled release multiple-units formulation in which individual units comprise cross-sectionally substantially homogeneous cores containing particles of a sparingly soluble active substance, the cores being coated with a coating which is substantially resistant to gastric conditions, but which is erodable under the conditions prevailing in the small intestine, in particular an enteric coating which is substantially insoluble at a pH below 7 such as Eudragit0 S (an anionic polymerisate of methacrylic acid and methacrylic acid methyl ester), is prepared by a process comprising comminuting an active substance together with a substance which is readily soluble in intestinal fluids such as an anionic detergent to obtain particles containing the active substance in intimate admixture with the readily soluble substance, combining the resulting particles into cross-sectionally substantially homogeneous cores together with components which accelerate the disintegration of the cores in intestinal fluids such as talc and sucrose, coating the individual cores with the coating, and combining a multiplicity of the coated cores into a capsule or tablet formulation.As the coating is erodable in an alkaline environment only, the active substance is not released until the units arrive at a section ofthe small intestine with an alkaline pH. Thus, a reduction and delay of the peak plasma concentration is obtained without affecting the extent of drug availability.A coating of the above-defined type may also be used when the active substance is a substance which exerts an irritating effect on the gastric mucosa and/or is unstable in an acidic environment.