Is there a risk of respiratory depression in prematurely born infants when breast-fed by mothers treated with ketobemidone?
The question was raised because a twin couple, born in gestational week 31, showed signs of respiratory depression and the mother was treated with Ketogan after a caesarean section.
The literature contains one systematic study of the passage of ketobemidone from plasma to milk (1). Data were obtained from five women given 5 mg ketobemidone sc preoperatively. Milk and plasma samples were collected simultaneously 3-21 hours after administration. The concentration in milk varied between 6 and 36 ng/ml and the authors estimate that at most one microgram of the 5 mg dose given to the mother will reach the systemic circulation of the infant assuming a 35 per cent oral availability. They did not measure ketobemidone in the infants.
Because the peak concentration of a drug depends on the volume of distribution, which usually is linearly related to body weight, it can be estimated that the peak concentration of ketobemidon in an infant will probably be less than 5 per cent of the peak concentration. This estimate is based on the assumption that the infant weighs one kg, the mother weighs 75 kg and that ketobemidone is 100 per cent orally available in the infant. Under steady state conditions the concentration is inversely proportional to the clearance of a drug. The clearance of ketobemidone in the premature newborn is unknown. It does, however, appear unlikely that clearance would be reduced by more than a factor 5000. It seems therefore reasonable to conclude, as they did in the study cited above, that harmful events are not expected in the breast-fed infant. In the present cases many other causes of respiratory depression may exist.
On the basis of one small study it is concluded that ketobemidone reaches breastmilk in low concentrations and there are, presently, no theoretical reasons to expect pharmacological effects in the breast-fed infant of mothers treated with ketobemidone.
Senast ändrad 2018-09-20