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Abstract

Discussion This study shows that a false increase in serum catecholamine induced by the administration of methyldopa level can be reduced by the simultaneous administration of barbiturate. Presumably methyldopa metabolism is accelerated by barbiturate. Buhs et al. (1964) showed that in man about half of ingested methyldopa is absorbed and that 50-90°0 of the amount absorbed is excreted within 48 hours. Of the metabolities methyldopa-mono-O-sulphate is found in largest quantities, and most probably the site of this phase of breakdown is the liver. Smaller amounts of 3-0-methyl-alphamethyldopa are demonstrable in the urine, and also alphamethyldopamine in the so-called neutral fraction, which is actually the first stage of methyldopa metabolism in man. Since at least part of methyldopa metabolism takes place in the liver and the effect of barbiturates on the microsomal enzymes of the liver has been proved, we suggest that methyl-dopa metabolism may be accelerated by barbiturates through enzyme induction. This phenomenon may have practical implications in the treatment of hypertensive patients. A West Indian child aged 13 months was found playing with white tablets and had one in his mouth. Fifteen minutes later he screamed loudly and became rigid. He remained rigid with intermittent crying until in the ambulance on the way to hospital, when he had a convulsion and a respiratory arrest. He was given mouth-to-mouth resuscitation and external cardiac massage. In the casualty department he continued to have fits repetitively and had five brief respiratory arrests within a short space of time. His airway was maintained and oxygen was given. During these convulsions he remained conscious and had facial grimacing with opisthotonos. At this time the nature of the tablets was unknown. Diazepam 2-5 mg given subcutaneously did not produce relaxation , but 2 5 mg intravenously, given in the course of an episode of severe muscle spasm complicated by respiratory arrest, produced immediate relaxation. His reflexes were still exaggerated and occasional extensor thrusts were evoked by minimal stimuli. By this time the tablets were morphologically identified as Easton's syrup (later confirmed by chromatography). Endotracheal intuba-tion was carried out after the intravenous administration of sux-amethonium and he was maintained with 100% oxygen and intermittent positive-pressure respiration. Gastric lavage was performed with sodium bicarbonate solution 45 minutes after ingestion of Easton's syrup tablets. An intramuscular injection of desferriox-amine mesylate was given because of the iron content of the tablets.