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Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006-.
CASRN: 555-30-6
Drug Levels and Effects
Summary of Use during Lactation
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.
Drug Levels
Maternal Levels. 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 gram daily.[1]
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.[2]
Infant Levels. No methyldopa was detectable (<200 mcg/L) in the serum of an infant whose mother was taking methyldopa 250 mg twice daily. The infant's urine contained a methyldopa concentration of 3.8 mg/L.[3]
In an 8-week-old infant whose mother was receiving 1 gram daily of methyldopa, a serum level of 90 mcg/L was found 10 hours after a 500 mg maternal dose. Another 1-week-old infant whose mother was receiving 500 mg daily had no detectable drug in the serum (<50 mcg/L).[2]
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 oral methyldopa 0.25 to 1.5 grams daily.[1-4]
Effects on Lactation and Breastmilk
Methyldopa can increase serum prolactin and has caused galactorrhea.[5-8] The maternal prolactin level in a mother with established lactation may not affect her ability to breastfeed.
Alternate Drugs to Consider
Candesartan, Benazepril, Captopril, Enalapril, Lisinopril, Quinapril, Hydrochlorothiazide, Methyldopa, Propranolol
References
- 1.
- Jones HM, 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 [PMC free article: PMC1429559] [PubMed: 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 [PubMed: 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 [PubMed: 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 [PubMed: 7202013]
- 5.
- Arze RS, Ramos JM, Rashid HU, et al. Amenorrhoea, galactorrhoea, and hyperprolactinaemia induced by methyldopa. Br Med J 1981;283:194 [PMC free article: PMC1506699] [PubMed: 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 [PubMed: 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 [PubMed: 4923681]
- 8.
- Cohen MA, Davies PH. Drug therapy and hyperprolactinaemia. Adv Drug React Bull 1998:723-6
Substance Identification
Substance Name
Methyldopa
CAS Registry Number
555-30-6
Drug Class
Breast Feeding
Lactation
Milk, Human
Antihypertensive Agents
Adrenergic alpha-2 Receptor Agonists
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- NTP Toxicology and Carcinogenesis Studies of alpha-Methyldopa Sesquihydrate (CAS No. 41372-08-1) in F344/N Rats and B6C3F1 Mice (Feed Studies).[Natl Toxicol Program Tech Rep ...]NTP Toxicology and Carcinogenesis Studies of alpha-Methyldopa Sesquihydrate (CAS No. 41372-08-1) in F344/N Rats and B6C3F1 Mice (Feed Studies).National Toxicology Program. Natl Toxicol Program Tech Rep Ser. 1989 Mar; 348:1-184.
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