A Magyar Fül-Orr-Gégeorvosok Egyesületének 1977. évi kongresszusa [antikvár]

ETHACRYNIC ACID XWDUCED POTENTIATION OF OTOTOXICITY-M.AHNICO, M.D. Karolinska sjukhuset, Stockholm, Sweden,_ The stria vascularis of the inner ear is of fundamental importance for the preservation of the specific ionic composition of the andolymph. Both morphologically and physiologically there exists similarities between the inner ear and the kidney. Ethacrynic acid is a widely used potent diuretic which mainly excerts its effects on the kidney tubules but it can under certain circumstances also affect the inner ear. This depends probably on an interference with the transport system for the exchange of Na+ and K"^ ions over the plasma membrane v/hich exists both in the kidney / for the preservation of the general body homeostasis / and the stria vascularis / for the preservation of the ionic composition of the endolymph /. Ethacrynic acid is supposed to inhibit this ionic transport system in both organs. A breakdown takes place of the normally occurring semipermeable barrier for the exchange of molecules between blood and endolymph. This would allow other ototoxic substances than ethacrynic acid to penetrate into the inner ear and excert their toxic effect /s/ on the labyrinthine hair cells at blood concentrations which normally would not cause ototoxic damage. Although the initial site of action is different for ethacrynic acid and e.g. aminoglycoside antibiotics or atoxyl their combined effect may result in a rapid destruction of the labyrinth. In conclusion, combinations of ethacrynic acid and other ototoxic substances should be avoided in clinical work. - 1 -