Because of the low levels of methyldopa in breastmilk, amounts ingested by the infant are small and would not be expected to cause any adverse effects in breastfed infants. No special precautions are required.
Three women who were 2 to 15 days postpartum were taking 250 mg of methyldopa orally 3 or 4 times daily. Randomly drawn milk samples had levels of drug and conjugate that ranged from < 0.1 to 0.5 mg/L at a dose of 750 mg daily and were 0.8 mg/L at a dose of 1 g daily.
In 3 women who were 1 to 8 weeks postpartum, peak levels of drug and conjugate occurred between 3 and 6 hours after the dose. Peak levels of drug and conjugate after a dose of 500 mg were 0.2, 0.66 and 1.14 mg/L in 3 mothers' milk. The authors estimated an infant dosage of less than 0.2% of the mother's total dosage.
No methyldopa was detectable (<200 mcg/L) in the serum on an infant whose mother was taking methyldopa 250 mg twice daily. The infant's urine contained a methyldopa concentration of 3.8 mg/L.
In an 8-week-old infant whose mother was receiving 1 g daily of methyldopa, a serum level of 90 mcg/L was found 10 hours after a 500 mg maternal dose; a 1-week-old infant whose mother was receiving 500 mg daily had no detectable drug in the serum (<50 mcg/L).
Effects in Breastfed Infants:
No acute or long-term adverse effects were reported in any 15 infants ranging in age from less than 1 week to 8 weeks of age whose mothers were taking methyldopa 0.25 to 1.5 g/day orally.
Possible Effects on Lactation:
Methyldopa can increase serum prolactin and has caused galactorrhea. The maternal prolactin level in a mother with established lactation may not affect her ability to breastfeed.
1. Jones HMR, Cummings AJ. A study of the transfer of alpha-methyldopa to the human foetus and newborn infant. Br J Clin Pharmacol. 1978;6:432-4. Letter. PMID:728288 2. White WB, Andreoli JW, Cohn RD. Alpha-methyldopa disposition in mothers with hypertension and in their breast-fed infants. Clin Pharmacol Ther. 1985;37:387-90. PMID:3838502 3. Hauser GJ, Almog S, Tirosh M et al. Effect of alpha-methyldopa excreted in human milk on the breast-fed infant. Helv Paediatr Acta. 1985;40:83-6. PMID:3843238 4. Hoskins JA, Holliday SB. Determination of alpha-methyldopa and methyldopate in human breast milk and plasma by ion-exchange chromatography using electrochemical detection. J Chromatogr. 1982;230:162-7. PMID:7202013 5. Arze RS, Ramos JM, Rashid HU et al. Amenorrhoea, galactorrhoea, and hyperprolactinaemia induced by methyldopa. Br Med J. 1981;283:194. PMID:6789964 6. Turkington RW. Prolactin secretion in patients treated with various drugs: phenothiazines, tricyclic antidepressants, reserpine, and methyldopa. Arch Intern Med. 1972;130:349-54. PMID:4560178 7. Vaidya RA, Vaidya AB, Van Woert MH et al. Galactorrhea and Parkinson-like syndrome: an adverse effect of alpha-methyldopa. Metabolism. 1970;19:1068-70. PMID:4923681 8. Cohen MA, Davies PH. Drug therapy and hyperprolactinaemia. Adv Drug React Bull. 1998;723-6.
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