Pentaerythritol Tetranitrate Sustained-Release Tablets: Relation of In Vitro Release of the Drug to Blood Pressure Changes after Administration to Anesthetized Cats

Abstract

The in vitro release of pentaerythritol tetranitrate (PET) from a sustained-action PET tablet was determined using USP tablet disintegration apparatus with the modification that 100-mesh stainless steel wire cloth replaced the usual 10-mesh. The immersion medium was simulated gastric fluid for the first 2 hr. and simulated intestinal fluid for the subsequent 10 hr. There was a gradual release of the drug and 80 to 100% of the drug was dissoluted at the end of 12 hr. The tablet when administered by mouth to anesthetized cats produced a 28 to 30% fall in arterial blood pressure which persisted for 12 hr. A good correlation between the rate of release of the drug in vitro and the in vivo effect in sustained lowering of the blood pressure was obtained. The in vitro method described is proposed for the quality control of sustained-action PET tablets.