Study of anaesthetic agents for their ability to elicit porphyrin biosynthesis in chick embryo liver

Effects of some anaesthetic drugs on the activity of delta-aminolevulinate synthetase and on the formation of porphyrins and cytochrome P-450 were studied in 18-day-old chick embryo livers in ovo. The drugs were either tested alone or with a small dose of 1,4-dihydro-3,5-dicarbethoxycollidine, which reproduces in the embryo liver a partial block in the heme biosynthesis pathway similar to that found in cells of human patients with porphyrias. Two series of local anaesthetics were tested: procaine and its derivatives (proxymetacaine, oxybuprocaine, butacaine and tetracaine) had no (or very slight) porphyrogenic effects. In contrast, lidocaine and its derivatives (bupivacaine, mepivacaine, etidocaine, pyrrocaine and prilocaine) were found to induce delta-aminolevulinate synthetase and to cause accumulation of porphyrins and cytochrome P-450. Some other drugs used in anaesthesiology were tested: fentanyl, morphine, sodium oxybate, pancuronium, pethidine and phenoperidine were found to be non-porphyrogenic; alcuronium was a slight inducer. It is suggested that the inducing drugs should be avoided in patients with hepatic porphyrias.