METHOXAMINE

Fetal Risk Summary

Methoxamine is a sympathomimetic used in emergency situations to treat hypotension. Because of the nature of its indications, experience with methoxamine in pregnancy is limited. Uterine vessels are normally maximally dilated and they have only a-adrenergic receptors (1). Use of the predominantly a-adrenergic stimulant methoxamine could cause constriction of these vessels and reduce uterine blood flow, thereby producing fetal hypoxia and bradycardia. These effects, including adverse effects on the fetal acid-base status, have been observed in pregnant ewes and monkeys at doses comparable to those used in humans (2).

Methoxamine may interact with oxytocics or ergot derivatives to produce severe persistent maternal hypertension (1). Rupture of a cerebral vessel is possible. If a pressor agent is indicated, other drugs, such as ephedrine, should be considered.

Breast Feeding Summary

No data are available.

References

1. Smith NT, Corbascio AN. The use and misuse of pressor agents. Anesthesiology 1970;33:58–101.
2. Product information. Vasoxyl. Glaxo Wellcome, 2000.