Based on the information available, there is no definitive answer regarding safe famciclovir substitutes for pregnancy. Famciclovir is a medication used to treat various viral infections, including herpes simplex and varicella-zoster virus infections. However, its safety during pregnancy has not been established [1].

When considering medication use during pregnancy, it is essential to weigh the potential risks and benefits for both the mother and the fetus. The U.S. Food and Drug Administration (FDA) classifies famciclovir as a pregnancy category B drug, which means that animal studies have not shown a risk to the fetus, but there are no well-controlled studies in pregnant women [2].

Several antiviral medications, such as acyclovir and valacyclovir, have been more widely studied and are often used during pregnancy for the treatment of herpes simplex virus infections [3]. These medications may be considered as potential substitutes for famciclovir during pregnancy, but it is crucial to consult a healthcare professional before making any medication decisions.

In summary, while there is no definitive list of safe famciclovir substitutes for pregnancy, other antiviral medications, like acyclovir and valacyclovir, may be considered based on their more extensive study and use during pregnancy. It is essential to consult a healthcare professional for personalized advice regarding medication use during pregnancy.

Sources:

1. Famciclovir - DrugBank. (n.d.). Retrieved from <https://go.drugbank.com/drugs/DB00612>
2. Famciclovir: MedlinePlus Drug Information. (2021). Retrieved from <https://medlineplus.gov/druginfo/meds/a601145.html>
3. Pregnancy and Herpes - ACOG. (n.d.). Retrieved from <https://www.acog.org/womens-health/faqs/pregnancy-and-herpes>