- CMV retinitis occurs very frequently and accounts for 85% of CMV disease in patients with AIDS.
- Treatment of CMV retinitis can be local or systemic and is administered in two phases, induction and maintenance.
- Valganciclovir, a ganciclovir prodrug, has been approved for use in CMV retinitis. Drug levels are equivalent to those of IV ganciclovir. For induction, 900 mg PO bid for 21 days is given, followed by 900 mg once a day. Treatment is indefinite unless immunologic recovery occurs. Adverse effects are similar to those of ganciclovir.
- Ganciclovir is given at an induction dosage of 5 mg/kg IV bid for 14â??21 days and a maintenance dosage of 5 mg/kg IV daily indefinitely (unless immune reconstitution occurs). The most common side effect of ganciclovir is myelotoxicity resulting in neutropenia. The neutropenia may respond to granulocyte colony-stimulating factor therapy. An intraocular ganciclovir implant is effective but does not provide systemic CMV therapy.
- Foscarnet is given at an induction dosage of 60 mg/kg IV q8h or 90 mg/kg IV bid for 14â??21 days, followed by a maintenance dosage of 90â??120 mg/kg IV daily indefinitely, unless immune reconstitution occurs. Nephrotoxicity is the major side effect; therefore, adequate hydration and electrolyte monitoring (including calcium) are required.
- Cidofovir is effective at an induction dosage of 5 mg/kg IV weekly for 2 weeks, followed by a maintenance dosage of 5 mg/kg IV every 2 weeks. Probenecid (2 g PO 3 hours before and 1 g PO 2 and 8 hours after cidofovir is given) and generous saline hydration must be used to reduce the renal toxicity of cidofovir. Urinalysis and electrolytes should be monitored closely.
- Fomivirsen is an antisense oligonucleotide given intraocularly, 330 mcg, on days 1 and 15 and then monthly. It does not provide systemic therapy.
- Combination regimens (ganciclovir and foscarnet) may be more effective than either drug alone, but together they are poorly tolerated.