Ganciclovir Dosing for Cytomegalovirus (CMV) Infections
For the treatment of CMV infections, intravenous ganciclovir should be administered at 5 mg/kg every 12 hours for 14-21 days (induction phase), followed by maintenance therapy based on the clinical scenario and immune status of the patient. 1
Initial Treatment (Induction Phase)
Standard Dosing
- IV Ganciclovir: 5 mg/kg administered intravenously every 12 hours for 14-21 days 1
- Administer over 1-2 hours to minimize adverse effects
Special Populations
- Newborns with congenital CMV: 6 mg/kg IV every 12 hours for 6 weeks 1
- Higher dose of 12 mg/kg/day has shown substantial decrease in viral load 1
- CMV encephalitis: Consider combination therapy with ganciclovir (5 mg/kg IV every 12h) and foscarnet (60 mg/kg IV every 8h or 90 mg/kg IV every 12h) for 3 weeks 1
Maintenance Therapy
- After induction: Lifelong maintenance therapy is recommended for immunocompromised patients, particularly those with HIV and CMV retinitis 1, 2
- Oral valganciclovir (prodrug of ganciclovir) may be used for maintenance therapy at 900 mg once daily 2, 3
Dosage Adjustments for Renal Impairment
Ganciclovir is primarily eliminated by the kidneys, requiring dose adjustment in renal impairment:
| Creatinine Clearance (mL/min) | Induction Dose | Maintenance Dose |
|---|---|---|
| ≥70 | 5 mg/kg q12h | 5 mg/kg q24h |
| 50-69 | 2.5 mg/kg q12h | 2.5 mg/kg q24h |
| 25-49 | 2.5 mg/kg q24h | 1.25 mg/kg q24h |
| 10-24 | 1.25 mg/kg q24h | 0.625 mg/kg q24h |
| <10 | 1.25 mg/kg 3x/week after hemodialysis | Not recommended |
Monitoring Requirements
- Complete blood count: Monitor frequently due to high risk of myelosuppression 1, 4
- Neutropenia occurs in up to 40% of patients and may require dose reduction 1
- Renal function: Monitor serum creatinine regularly 4
- CMV viral load: Consider monitoring to assess treatment response 1
- Ophthalmologic exams: Every 4-6 months for immunocompromised patients with CMV infection 1
Treatment Efficacy and Considerations
- Response rates for CMV retinitis are approximately 80% 6, 7
- Response rates for CMV pneumonitis are approximately 50-70% overall, with better outcomes in AIDS patients than in bone marrow transplant recipients 6
- Relapse is common after stopping therapy, necessitating maintenance treatment 6, 7
Common Pitfalls and Caveats
- Neutropenia risk: Ganciclovir should not be administered in patients with severe neutropenia (ANC <500/μL) 4
- Drug resistance: May develop with long-term therapy 1
- Inadequate dosing: Underdosing in patients with normal renal function can lead to treatment failure 5
- Overdosing in renal impairment: Patients with creatinine >3.0 mg/dL may have excessive trough levels despite standard dose adjustments 5
- High-risk patients: CMV-seronegative recipients of organs from CMV-seropositive donors have higher risk of treatment failure and may require more aggressive therapy 5
Alternative Approaches
- Foscarnet: Alternative for ganciclovir-resistant infections or in cases of severe neutropenia (60 mg/kg IV every 8h for induction) 1
- Combination therapy: For severe or resistant cases, particularly CMV encephalitis, combination of ganciclovir and foscarnet has shown improved outcomes 1
- Oral valganciclovir: Can achieve comparable systemic exposure to IV ganciclovir at a dose of 900 mg twice daily during induction phase 3, 8
Remember that dose adjustments and monitoring are critical to balance efficacy against the significant risk of adverse effects, particularly myelosuppression and renal toxicity.