Is Phenobarbital safe while breastfeeding?

Effects on the breastfed infant

Two 1-week-old infants whose mothers had been receiving phenobarbital 100 mg at bedtime for 3 to 5 nights exhibited deep slumber with difficulty in awakening that was possibly caused by phenobarbital in breastmilk.[ 8 ] A mother was taking phenobarbital 390 mg daily and phenytoin 400 mg daily during pregnancy and postpartum. Her infant was drowsy at birth, refused to suck and was given partial formula feeding. At 5 days of age, her infant was admitted to the hospital pale and collapsed with bruising, bleeding, and a decreased hemoglobin, thought to be due to methemoglobinemia. Breastfeeding was discontinued and the infant was given a transfusion which rapidly improved her condition. On day 10, the mother resumed breastfeeding the infant. Within 24 hours the infant was extremely sedated and refused to suck and was fed breastmilk with a spoon. The sedation persisted for 2 days until breastmilk was discontinued permanently because of a return of methemoglobinemia. The extreme sedation was probably due to phenobarbital in the milk and the methemoglobinemia was probably caused by the phenytoin.[ 9 ] An infant death occurred from overlying and suffocation by a parent during sleep. Sedation from phenobarbital, primidone, and phenytoin in breastmilk was possibly a contributing factor. Phenobarbital was found in the infant's serum (8 mg/L) and liver (16 mcg/g) on autopsy.[ 10 ] Probable drug withdrawal symptoms, manifested as spontaneous tremors, occurred in a breastfed infant in the third month of life when her mother who was taking phenobarbital (dose not stated) during pregnancy and breastfeeding, abruptly discontinued nursing.[ 11 ] A probable case of drug-induced drowsiness occurred in a newborn whose mother was taking primidone, carbamazepine and phenytoin (dosages not stated). At day 30, breastfeeding was discontinued because of the drowsiness that occurred after each feeding and poor weight gain. These authors also found that 13 partially breastfed infants whose moth

Effects on milk supply

No direct effect is known, but mothers taking antiepileptic drugs stop breastfeeding earlier and supplement more than mothers not taking antiepileptic drugs. Most of these reports occurred in older studies in which sedating agents such as phenobarbital and primidone were used. Infant sucking difficulties and sedation were reasons given for the reduced nursing.[ 12 , 14 ]

Levels in milk

In published reports of anticonvulsant use during breastfeeding, most women were taking a combination of anticonvulsants. Some other anticonvulsants (e.g., phenytoin, carbamazepine) stimulate the metabolism of other drugs including anticonvulsants, whereas others (e.g., valproic acid) inhibit the metabolism of other drugs. Therefore, the relationship of the maternal dosage to the concentration in breastmilk can be quite variable, making calculation of the weight-adjusted percentage of maternal dosage less meaningful than for other drugs in this database. Maternal Levels. In women taking phenobarbital for 3 days, average milk levels at 23 hours after the last dose were as follows: 90 mg daily in 4 women, 0.85 mg/L (range 0.8 to 1 mg/L); 150 mg daily in 2 women, 1.25 mg/L (range 1 to 1.5 mg/L); 225 mg daily in 2 women, 5.2 mg/L (range 2.7 to 5 mg/L). The same paper reported 2 women taking phenobarbital 125 mg 3 times daily along with phenytoin. Milk phenobarbital levels were fairly constant during the day, averaging from 5.6 to 6 mg/L at 6 am, 10 am and 8 pm in one woman between days 3 and 7 postpartum. In the other, milk levels averaged 7.3, 7.8 and 8.8 mg/L at 6 am, 10 am and 8 pm, respectively, between days 5 and 11 postpartum.[ 1 ] A breastmilk phenobarbital level of 2.7 mg/L was found 16 hours after the last dose in a patient taking 30 mg 4 times daily for 3.5 days at 6 days postpartum.[ 2 ] Eight phenobarbital breastmilk levels were measured between days 3 and 32 postpartum at unstated times after the dose in an unstated number of women who were taking phenobarbital and other anticonvulsants in unstated dosages. Phenobarbital milk levels averaged 10.4 mg/L (range 0.5 to 33 mg/L), while maternal serum levels averaged 19.3 mg/L.[ 3 ] Phenobarbital breastmilk concentrations were determined in a group of 26 mothers with epilepsy who were taking phenobarbital alone or in combination with other anticonvulsants. Determinations were made 4 times after delivery: within 5

Alternatives LactMed lists

• Midazolam
• Divalproex
• Gabapentin
• Lamotrigine
• Oxcarbazepine
• Phenytoin
• Valproic Acid