GANCICLOVIR SODIUM
Clinical safety rating: avoid
Other bone marrow suppressants may have additive effects Can cause severe myelosuppression and mutagenesis.
Ganciclovir is a synthetic guanine derivative that inhibits viral DNA synthesis. It is phosphorylated to ganciclovir triphosphate by viral thymidine kinase (CMV UL97 gene product) and cellular kinases. Ganciclovir triphosphate competitively inhibits viral DNA polymerase (CMV UL54 gene product) and incorporates into viral DNA, causing chain termination.
| Metabolism | Ganciclovir is minimally metabolized in the liver; it is predominantly excreted unchanged in the urine via glomerular filtration and active tubular secretion. The major metabolite is ganciclovir monophosphate, but it is not a significant pathway. No cytochrome P450 enzymes are involved. |
| Excretion | Renal: >90% unchanged drug via glomerular filtration and tubular secretion. Biliary/fecal: <1%. |
| Half-life | Terminal half-life: 2.5-3.6 hours in normal renal function; prolonged in renal impairment (up to 30 hours in severe cases). Dosage adjustment required for CrCl <80 mL/min. |
| Protein binding | 1-2% bound to plasma proteins (albumin). |
| Volume of Distribution | 0.74-0.96 L/kg, indicating extensive tissue distribution (including lung, liver, kidney, and brain). |
| Bioavailability | Oral: 6-9% (fasting); increased with food (up to 30% with high-fat meal). IV: 100%. |
| Onset of Action | IV: Within 1-2 hours; oral: 24-48 hours due to low bioavailability and need for intracellular phosphorylation. |
| Duration of Action | IV: 12-24 hours (dosing interval 12h); oral: half-life 4-5 hours, requires twice-daily dosing for maintenance. Clinical effect duration corresponds to viral suppression. |
5 mg/kg IV every 12 hours for 14-21 days for induction; 5 mg/kg IV once daily or 6 mg/kg IV once daily 5 days per week for maintenance. Oral ganciclovir not available as sodium salt.
| Dosage form | INJECTABLE |
| Renal impairment | CrCl 50-69 mL/min: 2.5 mg/kg IV q12h; CrCl 25-49 mL/min: 2.5 mg/kg IV q24h; CrCl 10-24 mL/min: 1.25 mg/kg IV q24h; CrCl <10 mL/min: 1.25 mg/kg IV 3 times weekly after hemodialysis. |
| Liver impairment | No specific adjustment required for hepatic impairment; monitor liver function if severe. |
| Pediatric use | Neonates and infants: 6 mg/kg/dose IV every 12 hours for 6 weeks for congenital CMV. Children: 5 mg/kg/dose IV every 12 hours for 14-21 days; maintenance 5 mg/kg/day IV once daily. Adjust for renal function. |
| Geriatric use | Start at lower end of dosing range due to age-related renal decline; adjust dose based on CrCl; monitor for myelosuppression. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Other bone marrow suppressants may have additive effects Can cause severe myelosuppression and mutagenesis.
| FDA category | Contraindicated |
| Breastfeeding | Ganciclovir is excreted into breast milk; M/P ratio is unknown in humans. Given potential for neonatal toxicity (bone marrow suppression, carcinogenicity), breastfeeding is contraindicated during therapy and for 7 days after last dose. |
| Teratogenic Risk | Ganciclovir is contraindicated in pregnancy due to teratogenicity demonstrated in animal studies (cleft palate, anophthalmia, hydronephrosis). First trimester exposure carries highest risk; second and third trimester risks include fetal growth restriction and hematologic toxicity. Use only if benefit outweighs risk. |
■ FDA Black Box Warning
Ganciclovir is associated with granulocytopenia, anemia, and thrombocytopenia. It is also potentially carcinogenic, mutagenic, and teratogenic. Animal studies have demonstrated carcinogenicity and teratogenicity. Ganciclovir should be considered a potential carcinogen.
| Common Effects | Myelosuppression |
| Serious Effects |
["Hypersensitivity to ganciclovir or acyclovir","Neutrophil count < 500 cells/mL","Platelet count < 25,000 cells/mL","Hemoglobin < 8 g/dL","Pregnancy (due to teratogenicity)"]
| Precautions | ["Hematologic toxicity: severe leukopenia, neutropenia, anemia, and thrombocytopenia; monitor blood counts frequently","Renal impairment: dose adjustment required based on creatinine clearance","Carcinogenicity: potential carcinogen based on animal studies","Teratogenicity: may cause fetal harm; avoid pregnancy","Mutagenicity: may cause chromosomal damage","Impaired fertility: causes aspermatogenesis in animals","Electrolyte imbalances: monitor calcium, magnesium, potassium, and phosphate","Drug interactions: increased risk of hematologic toxicity with myelosuppressive agents; increased risk of renal toxicity with nephrotoxic agents","Zidovudine coadministration may increase risk of severe neutropenia"] |
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| Fetal Monitoring | Monitor complete blood count (CBC) with differential and platelet count weekly; serum creatinine and hepatic enzymes. Fetal ultrasound for growth and anomalies. Monitor for maternal myelotoxicity, neurotoxicity, and renal impairment. For neonates, monitor CBC and renal function if inadvertent exposure. |
| Fertility Effects | Ganciclovir inhibits spermatogenesis and oogenesis in animal models; may cause reduced fertility in both sexes. In males, transient or permanent azospermia possible. In females, ovarian suppression and amenorrhea. Clinical significance in humans not fully established. |