The morantel sustained release trilaminate: A device for the controlled ruminal delivery of morantel to cattle

Abstract In vitro, in vivo performance, and model calculations of drug release from the morantel sustained release trilaminate (MSRT, Paratect Flex ® bolus — Pfizer Inc.) are presented. The device consists of an extruded sheet containing drug and ethylene vinyl acetate (EVA) sandwiched between thin films of EVA; a symmetrical pattern of circular perforations is punched through the sheet. Drug release occurs from the uncoated edges of the central lamina. Model release profiles for the device are presented; factors affecting the release rate and release profile are discussed. Both in vitro and in vivo release performance of devices containing morantel tartrate were evaluated and found to compare favorably with one another and the model. The MSRT demonstrated controlled delivery of morantel for 90 days both in vitro and in vivo .