May 19 2022

Classification of the active ingredient acebutolol

Risk level in pregnancy: This medicine is classified as Category B.

There is no appropriate and controlled trials on the use of acebutolol in pregnant women.

Reproduction studies in laboratory animals (rats, rabbits) at doses ranging from 6 to 30 times the average dose in humans, have resulted in fetal injury in either species.

In rabbits, at doses equivalent to six times the usual in human, there was a slight growth retardation, probably caused by the toxicity of the drug on the mother.

No human malformations were observed attributable to acebutolol, but experience with this drug during the first trimester of pregnancy is insufficient. In a comparative study with two beta blockers, the average birth weight of 56 infants was slightly lower compared to 38 infants exposed to pindolol, but somewhat higher than 31 babies of mothers treated with atenolol.

Some beta blockers can cause intrauterine growth retardation and reduced placental weight (atenolol, propranolol, etc..). Treatment with these drugs early in the second quarter results in the largest recorded intrauterine growth delays with these agents.

Although this has not been found in other beta-blockers, poor pharmacological differences with other drugs of the same group are suggestive that these phenomena may also occur.

Taking into count that growth retardation is a significant risk, this drug should be used during pregnancy only if the potential benefits exceeds the potential risk to the fetus.

For some authors, acebutolol and other beta-blockers should be classified in category D during the last two quarters, due to the increased risk of intrauterine growth retardation and decreased placental weight.

Update 18.07.2009

Meaning of category B

Animal reproduction studies have failed to demonstrate a risk to the fetus and there are no adequate and well-controlled studies in pregnant women OR Animal studies have shown an adverse effect, but adequate and well-controlled studies in pregnant women have failed to demonstrate a risk to the fetus in any trimester.