Ganciclovir is a synthetic nucleoside analogue of 2'-deoxyguanosine, classified as an antiviral agent. It is a potent inhibitor of replication of human cytomegalovirus (CMV) and other herpesviruses. In its active form (ganciclovir triphosphate), it competitively inhibits viral DNA polymerase and incorporates into viral DNA, leading to termination of DNA chain elongation. It is a critical drug for the management of CMV disease in immunocompromised patients, particularly those with HIV/AIDS and transplant recipients. In India, it is a cornerstone of therapy for CMV retinitis and systemic CMV infections.
Adult: **Induction:** 5 mg/kg IV every 12 hours for 14-21 days. **Maintenance:** 5 mg/kg IV once daily for 7 days/week, OR 6 mg/kg IV once daily for 5 days/week. **Oral (if available):** Not typically used for induction due to low bioavailability. Maintenance: 1000 mg orally three times daily with food.
Note: **For IV infusion only.** Reconstitute 500mg vial with 10 mL Sterile Water for Injection. Shake to dissolve. Further dilute the required dose (e.g., 250mg = 5mL of reconstituted solution) in 100 mL of compatible IV fluid (0.9% Sodium Chloride, 5% Dextrose, Ringer's Lactate). Infuse over 1 hour using an infusion pump. Avoid rapid or bolus administration (increases toxicity). Do not administer IM or SC. Handle with care (cytotoxic agent).
Ganciclovir is a prodrug that requires intracellular phosphorylation to its active triphosphate form. This phosphorylation is initially catalyzed by the virus-encoded protein kinase (UL97 gene product in CMV) in infected cells, providing some selectivity. The monophosphate form is further phosphorylated by cellular kinases to ganciclovir diphosphate and triphosphate (GCV-TP).
Pregnancy: **Pregnancy Category D (US FDA).** Teratogenic and embryotoxic in animal studies. There are no adequate and well-controlled studies in pregnant women. Should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Can cause fetal harm. Women of childbearing potential should use effective contraception during and for at least 30 days after therapy.
Driving: May cause dizziness, confusion, seizures, or hallucinations. Patients should be cautioned about operating machinery or driving until they know how ganciclovir affects them.
| Zidovudine (AZT) | Additive or synergistic myelosuppression (neutropenia, anemia). | Major |
| Mycophenolate Mofetil | Additive hematological toxicity (neutropenia). | Major |
| Imipenem-Cilastatin | Increased risk of seizures. | Major |
| Probenecid | Decreases renal clearance of ganciclovir, increasing plasma levels and risk of toxicity. | Moderate |
| Didanosine (ddI) | May increase didanosine levels; increased risk of pancreatitis and peripheral neuropathy. | Moderate |
| Other Nephrotoxic Drugs (Amphotericin B, Cyclosporine, Tacrolimus, Aminoglycosides, Foscarnet) | Increased risk of renal impairment. | Moderate |
| Trimethoprim/Sulfamethoxazole | Additive hematological toxicity. | Moderate |
Same composition (Ganciclovir (250mg)), different brands: