Phenobarbital Pregnancy and Breastfeeding Warnings
Phenobarbital Pregnancy Warnings
Phenobarbital has been assigned to pregnancy category D by the FDA. An increased risk of congenital malformations has been associated with use of anticonvulsants agents (including phenobarbital) during pregnancy. Anomalies associated with anticonvulsant use in pregnancy include neural tube defects, cleft lips, cleft palates, cardiac defects, and microcephaly. Neonatal barbiturate withdrawal symptoms have also been reported in infants whose mothers took phenobarbital during pregnancy. There are no controlled data in human pregnancy. Phenobarbital should only be given during pregnancy when there are no alternatives and benefit outweighs risk.
Phenobarbital exposure in utero has been reported to potentially have long term deleterious effects on cognitive performance. A recent prospective case control cohort study of pregnant women with epilepsy has reported that phenobarbital, phenytoin, and carbamazepine are all associated with an increased risk of fetal death and anomalies. In addition, of these three antiepileptic medications, phenobarbital was associated with the poorest pregnancy outcome in terms of fetal death and anomalies. Physicians are encouraged to register patients before fetal outcome is known (e.g., ultrasound, results of amniocentesis, etc) into the Antiepileptic Drug (AED) Pregnancy Registry at 1-888-233-2334 or 1-888-AED-AED4. This is an ongoing study at the Massachusetts General Hospital/Harvard Medical School. This study is designed to monitor the outcomes of pregnant women exposed to antiepileptic drugs in order to determine which therapies are associated with increased risk.
Phenobarbital Breastfeeding Warnings
Phenobarbital is excreted into human milk in small amounts. However, because of the prolonged half-life of the drug in neonates, accumulation of phenobarbital may occur and neonatal serum levels can potentially exceed maternal serum levels. Sedation and lethargy have been reported in nursing infants. The American Academy of Pediatrics classifies phenobarbital as a drug which has "caused significant effects in some nursing infants and should be given to nursing mothers with caution". Some investigators have recommended close monitoring of infant blood concentrations if a nursing mother must take phenobarbital.
References for pregnancy information
- Waters CH, Belai Y, Gott PS, Shen P, Degiorgio CM "Outcomes of pregnancy associated with antiepileptic drugs." Arch Neurol 51 (1994): 250-3
- Dravet C, Julian C, Legras C, Magaudda A, Guerrini R, Genton P, Soulayrol S, Giraud N, Mesdjian E, Trentin G, et al "Epilepsy, antiepileptic drugs, and malformations in children of women with epilepsy: a French prospective cohort study." Neurology 42 (1992): 75-82
- "Product Information. Phenobarbital (phenobarbital)." Lilly, Eli and Company, Indianapolis, IN.
- Reinisch JM, Sanders SA, Montensen EL, Rubin DB "In utero exposure to phenobarbital and intelligence deficits in adult men." JAMA 274 (1995): 1518-25
- Committee on Drugs "American Academy of Pediatrics Committee on Drugs: anticonvulsants and pregnancy." Pediatrics 63 (1979): 331-3
- Lindhout D, Meinardi H, Meijer JW, Nau H "Antiepileptic drugs and teratogenesis in two consecutive cohorts: changes in prescription policy paralleled by changes in pattern of malformations." Neurology 42 (1992): 94-110
- Yerby MS, Leavitt A, Erickson DM, McCormick KB, Loewenson RB, Sells CJ, Benedetti TJ "Antiepileptics and the development of congenital anomalies." Neurology 42 (1992): 132-40
- Schweigert BF "Neonatal barbiturate withdrawal." JAMA 221 (1972): 1282
- Koren G, Pastuszak A, Ito S "Drugs in pregnancy." N Engl J Med 338 (1998): 1128-37
References for breastfeeding information
- Roberts RJ, Blumer JL, Gorman RL, et al "American Academy of Pediatrics Committee on Drugs: Transfer of drugs and other chemicals into human milk." Pediatrics 84 (1989): 924-36
- Nau H, Kuhnz W, Egger HJ, Rating D, Helge H "Anticonvulsants during pregnancy and lactation. Transplacental, maternal and neonatal pharmacokinetics." Clin Pharmacokinet 7 (1982): 508-43
- Committee on Drugs, 1992 to 1993 "The transfer of drugs and other chemicals into human milk." Pediatrics 93 (1994): 137-50
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