Hydrazinophthalazine

Eclampsia

Published in Michael J. O’Dowd, The History of Medications for Women, 2020

Hydralazine (apresoline), hydrazinophthalazine (nepresol), nifedipine, methyldopa, Clonidine, diuretics and other antihypertensive agents such as reserpine, diazoxide, and labetalol were all resorted to, sometimes singly or in combination. Diazoxide and (di)hydrallazine were a potent mixture which caused extreme lowering of blood pressure leading to maternal collapse. Such drug interactions, with their uncertain synergistic effects, led to maternal deaths. Only hydrallazine, reported on by Assali (1954) and also by McCall (1954), remained popular and was combined with magnesium sulfate to form the drug therapy of choice.

N-acetyltransferase: the practical consequences of polymorphic activity in man

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Journal Information

Published in Xenobiotica, 2020

Stephen C. Mitchell

Hydralazine (1-hydrazinophthalazine) was patented in 1949 (Druey & Ringier, 1951; Hartmann & Druey, 1949) and has been used to treat high blood pressure and heart failure. It was one of the first orally available antihypertensive medications. However, the oral bioavailability of hydralazine in fast acetylators is less than one-half that achieved in slow acetylators. This phenomenon is not observed following intravenous administration and is due to pre-systemic metabolism presumably by N-acetyltransferase in the gut wall (Reece et al., 1980). It has been reported that fast acetylators experience a reduced therapeutic effect (Ramsay et al., 1984; Zacest & Koch-Weser, 1972) but this has been disputed by other workers (Hunyor, 1975; Vandenburg et al., 1982).

Hydrazinophthalazine

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Eclampsia

N-acetyltransferase: the practical consequences of polymorphic activity in man