VITRASERT
Clinical safety rating: caution
Comprehensive clinical and safety monograph for VITRASERT (VITRASERT).
Vitrasert (ganciclovir implant) releases ganciclovir, a nucleoside analog that inhibits cytomegalovirus (CMV) replication by competitively inhibiting viral DNA polymerase (UL54) after intracellular phosphorylation to ganciclovir triphosphate. This results in chain termination and viral DNA synthesis inhibition.
| Metabolism | Ganciclovir is primarily eliminated unchanged by the kidney via glomerular filtration and tubular secretion. Hepatic metabolism is minimal; no specific cytochrome P450 enzymes are involved. |
| Excretion | Primarily biliary/fecal (approximately 90%) with minimal renal excretion (<10% unchanged in urine). |
| Half-life | Terminal half-life of 2.8 hours following intravitreal injection; sustained local levels for 2-3 weeks. |
| Protein binding | Extensive (99% bound) primarily to albumin. |
| Volume of Distribution | Systemic Vd not clinically relevant; local ocular distribution ~4 mL (vitreous volume). |
| Bioavailability | Intravitreal: 100% (local). |
| Onset of Action | Intravitreal: within 2 weeks of injection. |
| Duration of Action | Intravitreal: approximately 3-4 months (single implant); effect may last up to 8 months. |
| Molecular Weight | 581.6 |
Intravitreal implant containing 0.59 mg fluocinolone acetonide; inserted into the vitreous cavity; releases drug over approximately 36 months; no systemic dosing.
| Dosage form | IMPLANT |
| Renal impairment | No dose adjustment required; renal impairment does not affect intravitreal pharmacokinetics. |
| Liver impairment | No dose adjustment required; hepatic impairment does not affect intravitreal pharmacokinetics. |
| Pediatric use | Not indicated for pediatric patients; safety and efficacy not established. |
| Geriatric use | No specific dose adjustment; same as adult dosing; monitor for intraocular pressure elevation and cataract progression. |
| 1st trimester | Contraindicated due to risk of fetal toxicity. Insufficient data, but animal studies show teratogenicity. |
| 2nd trimester | Contraindicated. Risk of fetal nephrotoxicity and ototoxicity. |
| 3rd trimester | Contraindicated. Risk of fetal nephrotoxicity, ototoxicity, and eighth cranial nerve damage. |
Clinical note
Comprehensive clinical and safety monograph for VITRASERT (VITRASERT).
| Placental transfer | Crosses placenta; achieves fetal serum concentrations approximately 50% of maternal levels. |
| Breastfeeding | Excreted into breast milk in low concentrations. Potential for infant toxicity, including hearing and renal impairment. Use caution; consider alternatives. |
| Lactation Rating |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to gentamicin or other aminoglycosidesMyasthenia gravisRenal impairmentPregnancyNeonates and infants (relative)History of ototoxicity with aminoglycosides
| Precautions | Severe leukopenia, neutropenia, anemia, thrombocytopenia, Potential for retinal detachment, Risk of endophthalmitis and vitreous hemorrhage with implantation procedure, Impaired renal function may require dose adjustment of systemic ganciclovir, Carcinogenicity, mutagenicity, and impairment of fertility observed in animal studies |
| Food/Dietary | No clinically significant food interactions. No dietary restrictions required. Maintain adequate hydration. |
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| L4 (Possibly Hazardous) |
| Teratogenic Risk | Vitrasert (ganciclovir implant) is classified as Category C. First trimester: There is no adequate human data, but animal studies show embryotoxicity and teratogenicity (e.g., cleft palate, anophthalmia). Second and third trimesters: Potential for fetal toxicity based on animal data, but limited human experience. Use only if benefit outweighs risk. |
| Fetal Monitoring | Monitor maternal complete blood count (neutropenia, thrombocytopenia), liver function tests, and serum creatinine. Fetal monitoring: Consider serial ultrasound for fetal growth and anatomy due to potential embryotoxicity. |
| Fertility Effects | Animal studies have shown decreased fertility in male and female rats at high doses. In humans, no specific data; however, ganciclovir may impair spermatogenesis and cause ovarian failure based on preclinical findings. |
| Clinical Pearls |
| Vitrasert is an intraocular implant containing ganciclovir used for the treatment of cytomegalovirus (CMV) retinitis in patients with AIDS. The implant provides localized therapy, reducing systemic toxicity. Monitor for retinal detachment, endophthalmitis, and visual acuity changes. Implant exchange is required every 5-8 months. Do not use in patients with active ocular infections or hypersensitivity to ganciclovir. |
| Patient Advice | This implant is placed in your eye to treat a viral infection of the retina caused by CMV. · You may experience temporary blurred vision after implantation; avoid driving until vision clears. · Report any sudden vision loss, eye pain, redness, or flashes of light immediately. · The implant releases medication for 5-8 months; you will need a procedure to replace it. · Do not rub or press on the treated eye; avoid swimming or hot tubs until healed. · Use preservative-free artificial tears if dryness occurs; do not use other eye drops without approval. |