Contraceptives and pseudocholinesterase medicamental interference.

The pseudocholinesterase (a mucoprotein closely related to the serum albumin which is produced in the liver) levels of 86 women who had been taking oral contraceptives (OCs) were measured and compared with a control group of 40 women. The duration of OC use varied from less than 1 year to more than 3 years. 4 patients were given single doses (1 mg/kg) of succinylcholine. Prolonged apnoea was observed in 2 patients for 25 and 65 minutes respectively. Depression of pseudocholinesterase correlated with duration of contraceptive use with depression occurring at the beginning of the 1st month and continuing until the 3rd year after which a very significant decline in the pseudocholinesterase level was observed. Age did not correlate with pseudocholinesterase level. Pseudocholinesterase levels of 62 and 24 were observed in the 2 women with prlonged apnea; both ahd been on OCs for 3 and 15 months respectively. To avoid hyperventilation or inhibition of the Hering-Breuer reflex manual ventilation was used. Nallynormorphine was used to treat the apnea which lasted 65 minutes. Both patients had reduced serum albumin; decreased "a"; increased "a2"; decreased "b"; increased "g"; and almost normal albumin-globulin ration. Both oxygenation acid base state and serum electrolytes were normal. The decrease in pseudocholinesterase occurs whenever there is a lesion in the liver which affects protein production. Studies have reported anovulatories cholestatic jaundiceor derangement of hepatic function in women taking OCs. Contraceptives are believed to act as hepatotoxic agents interfering in protein synthesis and in the energy exchange in the mitochondria of hepatic cells; the hepatotoxicity is attributed to the substitution of the 17th carbon of the alkali group in the a-position.