Vivitrol and Pregnancy
When given to pregnant rats and rabbits, Vivitrol (naltrexone injection) did not appear to increase the risk of birth defects. However, it did increase the risk for miscarriage. Vivitrol should only be used in a pregnant woman when the benefits to the woman outweigh the potential risks to the unborn child.
Vivitrol® (naltrexone injection) is a prescription medication used to treat alcohol dependence and to prevent relapse in people with opioid dependence. The medication may not be safe for use by pregnant women, although the full risks are unknown.
The U.S. Food and Drug Administration (FDA) uses a category system to classify the possible risks to a fetus when a specific medicine is taken during pregnancy. Vivitrol is classified as a pregnancy Category C medication.
Pregnancy Category C is given to medicines that have not been adequately studied in pregnant humans but do appear to cause fetal harm in animal studies. In addition, medicines that have not been studied in any pregnant women or animals are automatically given a pregnancy Category C rating.
Vivitrol has not been adequately studied in pregnant women. In animal studies, the active ingredient in Vivitrol (naltrexone) did not cause birth defects when given by mouth to pregnant rats or rabbits, even in high doses; however, it did increase the risk for miscarriage. Pregnant rats given the drug as a daily injection had babies that weighed more than pregnant rats not given the drug.
When naltrexone was given to male and female rats while they were mating, fewer female rats became pregnant. In addition, rats exposed to the medication while they were fetuses appeared to be less sensitive to the pain-relieving effects of morphine later in life.
However, it is important to note that animals do not always respond to medicines in the same way that humans do. Therefore, a pregnancy Category C medicine may be given to a pregnant woman if her healthcare provider believes that the benefits to the woman outweigh any possible risks to her unborn child.