Is breast-feeding safe if the mother is treated with atenolol?

Fråga: Is breast-feeding safe if the mother is treated with atenolol?

Sammanfattning: Most articles agree that atenolol is accumulated in breast-milk but as long as breast-feeding is avoided 3-4 hours after dose intake, the infant has normal renal function and is carefully monitored for adverse effects, breast-feeding is not contraindicated while treated with atenolol.

Svar: Similar questions have been answered several times before in Drugline (1-5) but all of them are more than 10 years old and an updated search was therefore done.

Atenolol belongs to group two in FASS (the Swedish catalog of approved medical products), which means that the drug is found in breastmilk but any influences on the infant are unlikely provided the drug is given in therapeutic doses.

A thorough literature search including Drugline, Medline and common pharmacological handbooks gave several articles concerning atenolol and breast-feeding.

Most of these articles (6-9) as well as the earlier Drugline-documents state that atenolol accumulates in milk and concentrations found are between 1.1-6.8 times greater than in serum. The doses ingested by the infants are much lower than therapeutic doses and no effects on the infants have been observed. The authors suggest however that the infants should be observed for untoward signs of beta-blockade, the mother should not breast-feed 3-4 hours after taking the medicine and that infants with any degree of renal insufficiency should not be breast-fed.

Only one case of adverse effect of breast-feeding while treated with atenolol was found (10). It concerns a girl who at five days of age had to be transferred to the intensive care unit because of cyanosis. Her rectal temperatue was 35.5 and she had two episodes of bradycardia, the heart rate returned to normal after tactile stimulation. Fourty-eight hours later, skin perfusion continued to seem poor. The breast-feeding was discontinued on day eight of the baby´s life and six hours later she was clinically normal. It was calculated that she would have ingested 9 mg of the 100 mg taken by her mother but these calculations have later been criticised (11) since that dose would equal 19.1 litre of milk. The reply to this by the original authors was that one could not use concentrations in milk to estimate the amount ingested by the child (12). 1 Drugline nr 04411 (year 1984)

2 Drugline nr 04273 (year 1984)
3 Drugline nr 03394 (year 1982)
4 Drugline nr 03068 (year 1982)
5 Drugline nr 02900 (year 1981)

6 Liedholm H, Melander A, Bitzen PO, Helm G, Lönnerholm G, Mattiasson I, Nilsson B: Accumulation of atenolol and metoprolol in human breast milk. Eur J Clin Pharmacol 1981; 20: 229-231 7 Thorley KJ, McAinsh J: Levels of the beta-blockers atenolol and propranolol in the breast milk of women treated for hypertension in pregnancy. Biopharm Drug Dispos 1983; 4: 299-301 8 White WB, Andreoli JW, Wong SH, Cohn RD: Atenolol in human plasma and breast milk. Obstet Gynecol 1984; 63(Suppl): 42S-44S 9 Kulas J, Lunell N-O, Rosing U, Steen B, Rane A: Atenolol and metoprolol. A comparison of their excretion into human breast milk. Acta Obstet Gynecol Scand 1984; Suppl 118: 65-69 10 Schmimmel MS, Eidelman AJ, Wilschanski MA, Shaw D Jr, Ogilvie RJ, Koren G: Toxic effects of atenolol consumed during breast feeding. J Pediatr 1989; 114: 476-478 11 Diamond JM: Toxic effects of atenolol consumed during breast feeding. J Pediatr 1989; 115: 336 12 Koren G: Reply to: Toxic effects of atenolol consumed during breast feeding. J Pediatr 1989; 115: 336