Sympatholytic (Antihypertensive)
PREGNANCY RECOMMENDATION: Human Data Suggest Risk in 2nd and 3rd Trimesters
BREASTFEEDING RECOMMENDATION: No Human Data—Potential Toxicity
PREGNANCY SUMMARY
No reports describing the use of penbutolol in human pregnancy have been located. If used near delivery, the newborn infant should be closely observed for 24–48 hours for signs and symptoms of β-blockade. Long-term effects of in utero exposure to β-blockers have not been studied but warrant evaluation.
Some β-blockers may cause intrauterine growth restriction (IUGR) and reduced placental weight, especially those lacking intrinsic sympathomimetic activity (ISA) (i.e., partial agonist). Treatment beginning early in the 2nd trimester results in the greatest weight reductions, whereas treatment restricted to the 3rd trimester primarily affects only placental weight. Penbutolol does possess ISA. However, IUGR and reduced placental weight may potentially occur with all agents within this class. Although growth restriction is a serious concern, the benefits of maternal therapy with β-blockers, in some cases, might outweigh the risks to the fetus and must be judged on a case-by-case basis.
FETAL RISK SUMMARY
Penbutolol is a nonselective β1, β2-adrenergic blocking agent used in the treatment of hypertension. No teratogenic effects were noted in mice, rats, and rabbits treated with doses up to 250 times the maximum recommended human dose (MRHD) (1,2). A slight increase in fetal and newborn mortality was observed in rabbits given 156 times the MRHD (2). In rats dosed at 200 times the MRHD, decreased pup body weight and survival were observed (2). In mice, the drug produced no behavioral changes in the exposed offspring (1).
BREASTFEEDING SUMMARY
No reports describing the use of penbutolol during human lactation have been located. If penbutolol is used during nursing, the infant should be closely monitored for hypotension, bradycardia, and other signs or symptoms of β-blockade. Long-term effects of exposure to β-blockers from milk have not been studied but warrant evaluation.
References
1.Sugisaki T, Takagi S, Seshimo M, Hayashi S, Miyamoto M. Reproductive studies of penbutolol sulfate given orally to mice. Oyo Yakuri 1981;22:289–305. As cited in Shepard TH. Catalog of Teratogenic Agents. 6th ed. Baltimore, MD: The Johns Hopkins University Press, 1989:487.
2.Product information. Levatol. Schwarz Pharma, 1997.