Baby Hints & Tips

Drug classifications in pregnancy

Drug ClassificationExpert tips by Tanya (Pharmacist)

Most medicines cross the placenta and have the potential to cause harm to a developing foetus or unborn child. Drug classifications help your health professional know which drugs are safe to take, which need to be considered carefully, and which need to be avoided. This is not information that should be considered without talking to your doctor and or pharmacist.

The categorisation system has taken into account the known harmful effects of medicines on the developing baby, including the potential to cause:

  • birth defects
  • unwanted pharmacological effects around the time of birth, which may or may not be reversible
  • problems in later life

When discussing the drug classifications, it is important to remember that:

  • The Australian categorisation system is not hierarchical. So, for example, a B category does not imply greater safety than a C category.
  • For pharmaceutical products containing two or more active ingredients, the categorisation of the combination is based on the active ingredient with the most restrictive pregnancy categorisation.
  • Due to legal considerations in Australia, sponsor companies have, in some cases, applied a more restrictive category than can be justified on the basis of the available data.

Definitions of the Australian categories for prescribing medicines in pregnancy

Category A
Drugs which have been taken by a large number of pregnant women and women of childbearing age without any proven increase in the frequency of malformations or other direct or indirect harmful effects on the fetus having been observed.

Category B
Human data is lacking or inadequate, and observations are based on animal date. There are three subcategories:

Category B1
Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have not shown evidence of an increased occurrence of fetal damage.

Category B2
Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals are inadequate or may be lacking, but available data show no evidence of an increased occurrence of fetal damage.

Category B3
Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.

Category C
Drugs which, owing to their pharmacological effects, have caused or may be suspected of causing, harmful effects on the human fetus or neonate without causing malformations. These effects may be reversible. Accompanying texts should be consulted for further details.

Category D
Drugs which have caused, are suspected to have caused or may be expected to cause, an increased incidence of human fetal malformations or irreversible damage. These drugs may also have adverse pharmacological effects. Accompanying texts should be consulted for further details. These drugs are not always contraindicated.

Category X
Drugs which have such a high risk of causing permanent damage to the foetus that they should not be used in pregnancy or when there is a possibility of pregnancy.

More information is available here:
http://www.tga.gov.au/hp/medicines-pregnancy-categorisation.htm

 

Tanya Burgess

Tanya Burgess (BPharm, Grad Dip Clinical Pharmacy) is the mother of 3 little girls and is a qualified pharmacist at Fremantle Hospital with over 14 years hospital pharmacy experience. To see all Tanya’s articles, click here.

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