Abstract: The present invention is concerned with improving the delivery of a drug from a ruminal delivery device to give a consistent delivery of drug to the ruminal environment. Thus, the invention is directed to an improved ruminal drug delivery device comprising a semipermeable membrane having an exit orifice and defining a compartment, the compartment containing a swellable osmotic agent expandable member, a drug to be dispensed, a density element and, optionally, a partition layer between the osmotic expandable member and the drug formulation, wherein the improvement comprises an essentially gas-impermeable barrier means that separates the density element from the other components within the delivery device for isolating gases evolved from the density element from the other components within the delivery device. The invention is also directed to methods and articles for providing a consistent delivery of drug from a ruminal drug delivery device.

Abstract: A density element (12) for use in ruminal delivery devices (10) which is manufactured by partial sintering in such a manner as to fragment upon contact with the many parts in rendering machinery without damage to the blades. The density element (12) has density of at least about 1.5 gm/cm.sup.3 and a transverse rupture strength greater than about 3000 psi no greater than about 30,000 psi. The part is sintered under conditions which do not permit full weld bond strength to be obtained and may thereafter be heat treated or impregnated with an inert hydrophobic material to increase corrosion resistance.