Sotalol Pregnancy and Breastfeeding Warnings
Sotalol Pregnancy Warnings
Sotalol has been assigned to pregnancy category B by the FDA. Animal studies have failed to reveal evidence of teratogenicity, but have revealed a slight increase in fetal death likely to be due to maternal toxicity when rabbits were given 16 times the maximum recommended human dose (on a mg/kg basis), and increased fetal absorptions when rats were given 100 times the maximum recommended human dose (on a mg/kg basis). There are no controlled data in human pregnancy. Sotalol should only be given during pregnancy when need has been clearly established.
Data from 12 pregnant women on a mean daily sotalol dose of 400 mg reveal a mean maternal plasma to umbilical cord sotalol level ratio of 1.05 to 1.00, indicating sotalol readily crosses the human placenta. The mean amniotic fluid concentration was 7.0 mcg/mL. No side effects related to sotalol were described in either the mothers or the infants. In a study evaluating the effectiveness of sotalol for the treatment of fetal tachycardia (n=18; maternal dosage range 160 to 480 mg daily), the authors reported that the mean fetal/maternal sotalol plasma concentration was 1.1 (range 0.67 to 2.87) and the mean amniotic fluid/fetal blood ratio was 3.2 (range 1.28 to 5.8). In addition, use of sotalol was not associated with fetal growth retardation. This study confirms that sotalol readily crosses the placenta. In another study of 16 pregnant women, the mean maternal to fetal plasma concentration ratio was 2.1 three hours after a single 80 mg dose was administered. No significant effects on fetal plasma renin activity were detected. A case of a 23-year-old woman who delivered a healthy, normal baby by Cesarean section three weeks before full term while receiving flecainide 100 mg twice a day and sotalol 80 mg twice a day is reported. At delivery, the maternal plasma to umbilical cord ratio was 0.7. The placenta was histologically normal, and the infant's heart rate and electrocardiogram were normal at delivery. A case of a 22-year-old woman who delivered a healthy, normal, 3.3 kg baby at 42 weeks' gestation while receiving sotalol 80 mg three times a day is reported. At delivery, the maternal plasma to umbilical cord concentration ratio was 1.18. Incidentally, the plasma clearance of sotalol is significantly increased during pregnancy relative to the postpartum state. This is thought to be due to increases in renal blood flow and glomerular filtration rate that occur during pregnancy.
Sotalol Breastfeeding Warnings
A case of a 22-year-old woman who delivered a healthy, normal, 3.3 kg baby at 42 weeks' gestation while receiving sotalol 80 mg three times a day is reported. The sotalol milk to maternal serum concentration ratio ranged from 2.4 to 5.6, indicating concentration of the drug in human milk. Assuming an average milk intake of 150 mL/kg/day, a nursing infant would receive approximately 20% to 23% of the maternal dose (on a mg/kg basis). The author of this case report stated that due to the relatively large concentration of sotalol in human milk, breast-feeding should be undertaken only when the infant is closely monitored for adverse side effects, such as bradycardia, hypotension, respiratory distress, or hypoglycemia. Other case reports and studies have confirmed milk to maternal plasma concentration ratios of 2.8 to 5.4.
Sotalol is excreted into human milk. Adverse effects in the infant are possible. The manufacturer recommends that due to the potential for serious adverse reactions in nursing infants, a decision should be made to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
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