HIV Drug Classifications for Pregnant Women

The Food and Drug Administration (FDA) has set up a class system (or rating system) for drugs used to treat pregnant women. Drugs are separated into five classes -- A, B, C, D and X. Here is what each of the classes means:

• Class A: Enough good studies in pregnant women show no risk to a developing baby, even in the first three months of pregnancy. This class is considered to be the safest.

• Class B: Studies in pregnant animals have shown no risk to a developing baby, but there are not enough studies in pregnant women to determine human risk.

• Class C: Safety in human pregnancy has not been determined and animal studies either show some risk to a developing baby or they have not been done. Drugs in this class should only be used if the possible benefits outweigh the possible risks to the baby.
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• Class D: There is some evidence of risk to a developing human baby, but the drug may still be used if its potential benefits are acceptable despite its potential risks.

• Class X: Various studies in animals or reports in humans have shown that the risk to a developing baby is too great to be used in pregnant women.

Each of these classes has been designed to show how much is known about using a particular drug during pregnancy. It does not necessarily mean that a class B drug is better than a class C drug. Among the HIV drugs, a class C rating means that some problems were detected in animal studies (animals are frequently given doses many times higher than humans receive). It can also mean that nothing was seen in animal studies, but not enough research has been done to give the drug a class A or B rating.

Ultimately, the class system alone is not enough information to make a choice about treatments. You must also take into account your treatment history, what drugs you are resistant to, concerns about side effects and the dosing schedule or requirements of a potential regimen. Some drugs should not be taken in combination by pregnant women (ddI and d4T) and some should be avoided altogether because of the type of birth defects seen in animal studies (Sustiva). Other drugs should be used with caution (Viramune). Speak to your doctor to come up with the combination that is right for you.

For the complete chart go to: www.aidsinfo.nih.gov/guidelines/perinatal/PER_112603.pdf (See Table #2.)

Dawn Averitt is the founding director of WISE and a national AIDS treatment advocate and educator.