ETHCHLORVYNOL

Fetal Risk Summary

No reports linking the use of ethchlorvynol with congenital defects have been located. In pregnant rats, a dose of 40 mg/kg/day was associated with an increase in the number of stillbirths and a lower survival rate among the offspring (1).

The Collaborative Perinatal Project reported 68 patients with 1st trimester exposure to miscellaneous tranquilizers and nonbarbiturate sedatives, 12 of which had been exposed to ethchlorvynol (2). For the group as a whole, six infants with malformations were delivered, but details on individual exposures were not given.

Animal data indicate that rapid equilibrium occurs between maternal and fetal blood with maximum fetal blood levels measured within 2 hours of maternal ingestion (3). The authors concluded that following maternal ingestion of a toxic or lethal dose, delivery should be accomplished before equilibrium occurs. Neonatal withdrawal symptoms, consisting of mild hypotonia, poor suck, absent rooting, poor grasp, and delayed-onset jitteriness, have been reported (B.H. Rumack, P.A. Walravens, personal communication, Dept. of Pediatrics, Univ. of Colorado Medical Center, 1981). The mother had been taking 500 mg daily during the 3rd trimester.

Breast Feeding Summary

No reports describing the use of ethchlorvynol during human lactation have been located. Because the drug rapidly crosses the placenta to the fetus, excretion into milk should be expected. Sedation of the nursing infant is a possible consequence.

References

1. Product information. Placidyl. Abbott Laboratories, 2000.
2. Heinonen OP, Slone D, Shapiro S. Birth Defects and Drugs in Pregnancy. Littleton, MA:Publishing Sciences Group, 1977:336–7.
3. Hume AS, Williams JM, Douglas BH. Disposition of ethchlorvynol in maternal blood, fetal blood, amniotic fluid, and chorionic fluid. J Reprod Med 1971;6:54–6.