MEPINDOLOL

Fetal Risk Summary

Mepindolol is a nonselective b-adrenergic blocking agent. No reports of its use in pregnancy have been located.

The use near delivery of some agents in this class has resulted in persistent b-blockade in the newborn (see Acebutolol, Atenolol, and Nadolol). Thus, newborns exposed in utero to mepindolol should be closely observed during the first 24–48 hours after birth for bradycardia and other symptoms. The long-term effects of in utero exposure to b-blockers have not been studied but warrant evaluation.

Some b-blockers may cause intrauterine growth retardation and reduced placental weight (e.g., see Atenolol and Propranolol). Treatment beginning early in the 2nd trimester results in the greatest weight reductions. This toxicity has not been consistently demonstrated in other agents within this class, but the relatively few pharmacologic differences among the drugs suggests that the reduction in fetal and placental weights probably occurs with all at some point. The lack of toxicity documentation may reflect the number and type of patients studied, the duration of therapy, or the dosage used, rather than a true difference among b-blockers. Although growth retardation is a serious concern, the benefits of maternal therapy with b-blockers may, in some cases, outweigh the risks to the fetus and must be judged on a case-by-case basis.

[*Risk Factor D if used in 2nd or 3rd trimesters.]

Breast Feeding Summary

Mepindolol is excreted into breast milk (1). Following a 20-mg dose, mean milk concentrations in five mothers at 2 and 6 hours were 18 and 16 ng/mL, respectively, with a milk:plasma ratio at 2 hours of 0.35. Continuous dosing of 20 mg daily for 5 days produced milk levels at 2 and 6 hours of 22 and 33 ng/mL. The milk:plasma ratio at 6 hours was 0.61. At a detection limit of 1 ng/mL, mepindolol could be found in the serum of only one of the five breast-fed infants. Although no adverse effects were observed, nursing infants should be closely watched for bradycardia and other signs and symptoms of b-blockade. Long-term effects of exposure to b-blockers from milk have not been studied but warrant evaluation.

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