Experimental studies of the breakdown of epontol: Determination of propanided in human serum

Abstract

Summary: The concentration of propanidid in human serum was determined and was found to depend on the rate of injection. None was found 25 minutes after injection over a 20-second period. Propanidid passed the placental barrier, the umbilical vein concentration depending on the dose injected. Serum cholinesterase was inhibited by propanidid both in vivo and in vitro; the red-cell esterase was also inhibited. The concentration in umbilical vein blood was highest in mothers with reduced cholinesterase activity. The duration of anaesthesia appears to be influenced by serum cholinesterase activity. In vitro, enzymatic hydrolysis in human serum was slow but occurred rapidly in purified concentrated cholinesterase. When suxamethonium was injected after Epontol the period of apnoea was increased and this is ascribed to enzyme inhibition. The e.e.g. was useful in determining the duration of anaesthesia. Prolongation of anaesthesia in subjects with low enzyme activity corresponded with the e.e.g. findings. Propanidid is bound to plasma proteins and it is recommended that a dose of 3-4 mg/kg of Epontol is sufficient for induction of anaesthesia in high-risk patients. © 1968 John Sherratt and Son Ltd.