Abstract: There is disclosed a slow release drug delivery device for the prolonged administration of topically active medicines which consists of a vehicle in which water is soluble and in which is dissolved the topically active drug which is formed into a stable organogel with a polymer matrix with a very low water absorbing capability. The organogel, in the presence of water or atmospheric water vapor, slowly imbibes such water into the vehicle and by doing so the vehicle becomes incompatible with the matrix and is slowly expelled therefrom. The vehicle dissolves the drug and the vehicle/drug combination is slowly pumped out of the polymeric matrix with substantially linear drug delivery occurring for periods in excess of 6 months. The drug delivery device may be used to administer drugs topically, as a collar or trans dermal patch, orally, as a slow delivery device, particularly as a ruminal bolus, or as a suppository or a subcutaneous implant.