Risk Summary

After oral administration, valganciclovir (prodrug) is converted to ganciclovir (active drug) and, therefore, valganciclovir is expected to have reproductive toxicity effects similar to ganciclovir. In animal studies, ganciclovir caused maternal and fetal toxicity and embryo-fetal mortality in pregnant mice and rabbits as well as teratogenicity in rabbits at exposures two-times the human exposure. There are no available human data on use of valganciclovir or ganciclovir in pregnant women to establish the presence or absence of drug-associated risk. The background risk of major birth defects and miscarriage for the indicated populations is unknown. However, the background risk in the U.S. general population of major birth defects is 2 to 4% and the risk of miscarriage is 15 to 20% of clinically recognized pregnancies. Advise pregnant women of the potential risk to the fetus [see Warnings and Precautions (5.3), Use in Specific Populations ( 8.3)]. 

Clinical Considerations

Disease-associated maternal and/or embryo/fetal risk

Most maternal CMV infections are asymptomatic or they may be associated with a self-limited mononucleosis-like syndrome. However, in immunocompromised patients (i.e., transplant patients or patients with AIDS) CMV infections may be symptomatic and may result in significant maternal morbidity and mortality. The transmission of CMV to the fetus is a result of maternal viremia and transplacental infection. Perinatal infection can also occur from exposure of the neonate to CMV shedding in the genital tract. Approximately 10% of children with congenital CMV infection are symptomatic at birth. 

Mortality in these infants is about 10%and approximately 50 to 90% of symptomatic surviving newborns experience significant morbidity, including mental retardation, sensorineural hearing loss, microcephaly, seizures, and other medical problems. The risk of congenital CMV infection resulting from primary maternal CMV infection may be higher and of greater severity than that resulting from maternal reactivation of CMV infection.

Data

Animal Data

Doses resulting in two-times the human exposure of ganciclovir (based on the human AUC following a single intravenous infusion of 5 mg per kg of ganciclovir) resulted in maternal and embryo-fetal toxicity in pregnant mice and rabbits as well as teratogenicity in the rabbits. Fetal resorptions were present in at least 85% of rabbits and mice. Rabbits showed increased embryo-fetal mortality, growth retardation of the fetuses and structural abnormalities of multiple organs of the fetuses including the palate (cleft palate), eyes (anophthalmia/microphthalmia), brain (hydrocephalus), jaw (brachygnathia), kidneys and pancreas (aplastic organs). Increased embryo-fetal mortality was also seen in mice. Daily intravenous doses of approximately 1.7 times the human exposure (based on AUC) administered to female mice prior to mating, during gestation, and during lactation caused hypoplasia of the testes and seminal vesicles in the male offspring, as well as pathologic changes in the nonglandular region of the stomach. 

Data from an ex-vivo human placental model showed that ganciclovir crosses the human placenta. The transfer occurred by passive diffusion and was not saturable over a concentration range of 1 to 10 mg/mL.