GANZYK-RTU
Clinical safety rating: caution
Comprehensive clinical and safety monograph for GANZYK-RTU (GANZYK-RTU).
Ganciclovir is a synthetic guanine derivative that inhibits viral DNA synthesis by phosphorylation to ganciclovir triphosphate, which competitively inhibits viral DNA polymerase and incorporation into viral DNA, causing chain termination.
| Metabolism | Ganciclovir is not significantly metabolized; it is primarily excreted unchanged via glomerular filtration and active tubular secretion. Small amount is metabolized to a 9-carboxymethoxymethyl guanine derivative. |
| Excretion | Primarily renal via glomerular filtration and tubular secretion; >90% of dose excreted unchanged in urine; biliary/fecal elimination <5%. |
| Half-life | Terminal elimination half-life approximately 3–4 hours in patients with normal renal function; prolonged to 10–24 hours in moderate to severe renal impairment (CrCl <50 mL/min), requiring dose adjustment. |
| Protein binding | 1–2% bound to plasma proteins (negligible binding, primarily albumin). |
| Volume of Distribution | 0.47–0.73 L/kg, suggesting distribution into total body water with some tissue penetration (e.g., lung, liver, kidney). |
| Bioavailability | Oral bioavailability of ganciclovir (prodrug valganciclovir) is approximately 60% after oral administration of valganciclovir; ganciclovir itself has <10% oral bioavailability. |
| Onset of Action | Not applicable for oral route; for intravenous administration, antiviral effect begins within 24–48 hours based on viral titer reduction. |
| Duration of Action | Duration of antiviral effect is approximately 8–12 hours post-IV dose, supporting twice-daily dosing in immunocompetent patients; longer in renal impairment. |
| Molecular Weight | Ganciclovir (active base) 255.2 Da; Ganciclovir sodium (prodrug) 277.2 Da. |
5 mg/kg IV every 12 hours for 14-21 days.
| Dosage form | SOLUTION |
| Renal impairment | CrCl ≥70 mL/min: 5 mg/kg q12h; CrCl 50-69: 2.5 mg/kg q12h; CrCl 25-49: 2.5 mg/kg q24h; CrCl 10-24: 1.25 mg/kg q24h; CrCl <10: 1.25 mg/kg three times weekly after hemodialysis. |
| Liver impairment | No dose adjustment recommended for Child-Pugh A, B, or C. Monitor liver function. |
| Pediatric use | Neonates: 6 mg/kg/dose IV q12h for 14-21 days. Infants and children: 5 mg/kg/dose IV q12h for 14-21 days. |
| Geriatric use | Base dosing on renal function (CrCl); increased risk of nephrotoxicity and myelosuppression; monitor CBC and renal function closely. |
| 1st trimester | Contraindicated: embryotoxicity and teratogenicity observed; avoid use unless no safer alternative and clearly needed. |
| 2nd trimester | Use only if potential benefit justifies risk to fetus; may cause fetal harm. |
| 3rd trimester | Use only if clearly needed; possible neonatal toxicity (e.g., bone marrow suppression). |
Clinical note
Comprehensive clinical and safety monograph for GANZYK-RTU (GANZYK-RTU).
| Placental transfer | Crosses placenta actively; detectable in fetal serum at concentrations similar to maternal. |
| Breastfeeding | Excreted into breast milk; potential for serious adverse reactions in nursing infant (e.g., bone marrow suppression, nephrotoxicity). Discontinue breastfeeding or discontinue drug, considering importance to mother. |
■ FDA Black Box Warning
Ganciclovir is associated with granulocytopenia, anemia, and thrombocytopenia. Animal studies have demonstrated carcinogenicity, teratogenicity, and impairment of spermatogenesis. Use only when potential benefit outweighs risk.
| Serious Effects |
Hypersensitivity to ganciclovir or valganciclovirAbsolute neutrophil count <500/μLPlatelet count <25,000/μLHemoglobin <8 g/dL
| Precautions | Hematologic toxicity: granulocytopenia, anemia, thrombocytopenia; monitor CBC frequently, Renal impairment: dose adjustment required based on creatinine clearance, Carcinogenicity and teratogenicity: avoid pregnancy and breastfeeding, Impaired spermatogenesis: use caution in men of reproductive potential, Central nervous system effects: seizures, dizziness, ataxia; avoid driving or operating machinery |
| Food/Dietary | No known food interactions. Maintain adequate hydration. Grapefruit juice has no reported interaction with ganciclovir. |
Loading safety data…
| Lactation Rating |
| L4 (Possibly Hazardous) |
| Teratogenic Risk | First trimester: Avoid due to potential teratogenicity based on animal studies (skeletal and visceral malformations). Second and third trimesters: Use only if clearly needed; may cause fetal harm (e.g., low birth weight, hematologic toxicity). |
| Fetal Monitoring | Monitor maternal complete blood count (CBC) with differential, renal function (serum creatinine, BUN), and hepatic function (ALT, AST) regularly. Perform fetal ultrasound for growth and anatomy if used during pregnancy. |
| Fertility Effects | May cause reduced fertility in animal studies (impairment of spermatogenesis and oogenesis); human data limited. |
| Clinical Pearls | GANZYK-RTU is a ready-to-use (RTU) formulation of ganciclovir. It must be administered intravenously; do not switch with oral ganciclovir or valganciclovir without dose adjustment. Monitor renal function closely, as dose reduction is required for CrCl <70 mL/min. Neutropenia is dose-limiting; check CBC twice weekly. Avoid extravasation; administer via central line if possible. Ganciclovir is a potential carcinogen and mutagen; handle with cytotoxic precautions. |
| Patient Advice | This medication is given through a vein (IV) and is not taken by mouth. · You will need regular blood tests to check kidney function and blood cell counts. · Tell your doctor if you have easy bruising, bleeding, fever, or signs of infection. · Use effective contraception during treatment and for at least 90 days after the last dose. · Do not drive or operate machinery if you experience confusion, dizziness, or seizures. · Report any pain, redness, or swelling at the IV site immediately. |