Film-coated matrix core tablet

Claim 1

A pharmaceutical tablet for continuous release of a medicament during a predetermined dissolution period of at least 5 hrs. and up to 8 hrs. following ingestion by a mammal comprising a core constituting at least 95% of the tablet weight and containing at least 0.75 g. of a water soluble medicament and coated with a permeable erosion resistant polymeric film, said core comprising a compressed granulation containing from 72% to 85% by weight of said core of said water soluble medicament and from 13% to 25% by weight of said core of a water insoluble material having a wax-like consistency said film being continuous and constituting up to 5% of the tablet weight and being comprised of a major proportion of a polymeric material and a minor proportion of a plasticiser therefor wherein said polymeric material, said plasticiser, and the quantities thereof are selected so that said film remains intact for at least a portion of said dissolution period and confers a dissolution profile upon said tablet when measured by the rolling bottle method and expressed as percent by weight of medicament contained in said tablet dissolved per unit of time of from 45 to 75% during the first 3 hours of said dissolution period, a maximum of 25% during the first hour of said dissolution period, at least 66% during the first 5 hours, and at least 90% during the entire 8 hour dissolution period, the amount of medicament dissolved during the first hour of said dissolution period deviating by no more than 22% from the average hourly amount thereof dissolved during the first 3 hours of said dissolution period, and wherein the amount of medicament dissolved during the first hour of said dissolution period from said core in the absence of said film and measured by the rolling bottle method exceeds the average hourly amount thereof dissolved during the first 3 hours of said dissolution period by more than 22%.