GUANABENZ

Fetal Risk Summary

Guanabenz is a centrally acting, a2-adrenergic agonist that acts as an antihypertensive agent by decreasing sympathetic outflow from the brain. In one study, no increase in fetal malformations was observed in rats and rabbits treated with the drug during organogenesis (1). However, an increase in perinatal mortality was observed with doses that produced sedation in the mothers. In mice, oral doses of guanabenz 3–6 times the maximum recommended human dose resulted in a possible increase in skeletal malformations, primarily costal and vertebral (2). No reports describing the use of guanabenz in human pregnancy have been located.

Breast Feeding Summary

No reports describing the use of guanabenz during lactation have been located. The relatively low molecular weight (about 291), however, probably indicates that the drug is excreted into breast milk. The potential effects on a nursing infant from this exposure are unknown.

References

1. Akatsuka K, Hashimoto T, Takeuchi K, Yanagisawa Y, Kogure M. Reproduction studies of guanabenz in the rat and rabbit. J Toxicol Sci 1982;11:93–151. As cited in Shepard TH. Catalog of Teratogenic Agents. 6th ed. Baltimore, MD:Johns Hopkins University Press, 1989:305.
2. Product information. Wytensin. Wyeth-Ayerst Laboratories, 1993.