In recent decades, knowledge of how biochemical compounds known as inosines metabolize has brought about significant advances in immunotherapy. This has led to the development of the immunosuppressant drugs mycophenolate mofetil (MMF) and mycophenolate acid (MPA), which are used primarily to prevent rejection in organ transplantation (MMF has also been used to treat lupus erythematosus, erythema multiforme, and rheumatoid arthritis).
Both of these drugs had been suspected of causing harm to human embryos when taken during pregnancy. But in October 2007, Roche Laboratories, the maker of CellCept, which contains MMF as its active ingredient, issued an open letter to health professionals informing them that the drug’s pregnancy category had been changed from “C” to “D”, signifying that its use was associated with pregnancy loss and congenital malformations. The change was prompted by postmarketing data collected from cases of women exposed to systemic MMF during pregnancy, and data from the United States Transplantation Pregnancy Registry (NTPR).
Then a May 16, 2008 U.S. Food and Drug Administration (FDA) alert warned that the agency had become aware of reports of infants who had been born with serious congenital anomalies, including cleft lip and palate and microtia (small ear) following exposure to MMF during pregnancy. The alert further warned that both MMF and MPA (marketed under the trade name Myfortic by Novartis) increase the risk of a miscarriage in the first trimester and can cause congenital malformations in the children of women who are treated during pregnancy.
The FDA recommends that prior to taking MMF or MPA, women of childbearing potential should let their doctor know if they are planning a pregnancy. And prior to prescribing MMF or MPA to women of childbearing potential, clinicians should confirm that they are not pregnant and provide them with:
- Information about the risk of fetal harm from exposure to MMF or MPA during pregnancy
- Counseling about contraceptive options
- Instruction on the appropriate use of contraceptive methods
If a patient becomes pregnant while taking these drugs, or if therapy with these drugs must be undertaken in a patient who is already pregnant, the patient should be apprised of the risk to the fetus.
The FDA is working with the makers of MMF and MPA to mitigate the risks of fetal exposure.