Valganciclovir in Pregnancy: Dosing and Side Effects
Valganciclovir is recognized as the treatment of choice during pregnancy for symptomatic CMV infection, but should be started after the first trimester to minimize fetal exposure to systemic antiviral drugs. 1, 2
Recommended Dosing
For pregnant women requiring treatment for CMV infection:
- Treatment should be initiated after the first trimester whenever possible 1, 2
- Standard adult dosing is typically used:
Indications for Use in Pregnancy
Valganciclovir should be used in pregnancy only when:
- The pregnant woman has symptomatic CMV infection 1, 2
- There is evidence of CMV end-organ disease (such as retinitis) 1
- Fetal ultrasound shows evidence of CMV infection 2
For retinal disease in the first trimester, intraocular implants or intravitreous injections should be considered for local therapy to limit fetal exposure to systemic antiviral drugs 1, 2.
Potential Side Effects and Risks
Maternal Side Effects
- Myelosuppression (most common adverse effect) 1, 3:
- Neutropenia
- Anemia
- Thrombocytopenia
- Renal toxicity 3
- Gastrointestinal effects (diarrhea, nausea, vomiting) 3
- Headache 3
- CNS effects 3
- Elevated liver enzymes 3
Fetal/Neonatal Risks
Animal studies have shown:
- Embryotoxicity in rabbits and mice 3
- Teratogenicity in rabbits (cleft palate, anophthalmia/microphthalmia, hydrocephalus, kidney and pancreas abnormalities) 3
- Fetal resorptions in rabbits and mice 3
However, recent pharmacovigilance data suggests no increased reporting of adverse pregnancy outcomes with valganciclovir compared to valaciclovir 4.
Monitoring During Treatment
Maternal Monitoring
- Complete blood counts with differential should be performed frequently to monitor for myelosuppression 3
- Renal function tests should be monitored regularly 3
- Liver function tests 3
Fetal Monitoring
- Fetal movement counting in the third trimester 1, 2
- Periodic ultrasound monitoring after 20 weeks of gestation to look for:
Important Considerations and Precautions
- Valganciclovir is mutagenic and potentially carcinogenic 3
- Contraception is recommended during treatment and for at least 30 days following treatment for females and 90 days for males 3
- Treatment of asymptomatic maternal CMV infection during pregnancy solely to prevent infant infection is not indicated 1, 2
- Referral to a maternal-fetal medicine specialist is recommended for evaluation, counseling, and potential further testing 1, 2
Alternative Treatments
If valganciclovir is contraindicated or not tolerated:
- Ganciclovir (IV) at 5 mg/kg every 12 hours for 14-21 days, followed by maintenance therapy 1
- Foscarnet (60 mg/kg IV every 8 hours for 14-21 days) can be considered for ganciclovir-resistant CMV infections 1
- Cidofovir is embryotoxic and teratogenic and should not be used during pregnancy 1
Emerging Evidence
Recent research suggests:
- A small observational study found valganciclovir (3 × 450 mg per day) appears to be well-tolerated for both mother and fetus when used for tertiary prevention in infected fetuses showing ultrasound features of infection 5
- Valacyclovir has shown promise in reducing maternal-fetal CMV transmission, particularly in first and second-trimester infections 6, 7
While valganciclovir carries theoretical risks based on animal studies, its use may be justified when the benefits of treating symptomatic CMV infection outweigh the potential risks to the fetus, particularly when treatment is initiated after the first trimester.