Foscarnet

Foscarnet is an inorganic pyrophosphate compound that inhibits viral DNA polymerase, RNA polymerase, or HIV reverse transcriptase directly. It has in vitro activity against HSV, VZV, CMV, EBV, HHV-6, HBV, and HIV.

The drug is available in an intravenous formulation only. Cerebrospinal fluid concentrations are approximately two-thirds of steady state serum concentrations. Clearance of foscarnet is primarily by the kidney. The initial elimination half-life is 4-8 hours, followed by a prolonged terminal elimination half-life of 3-4 days in patients with normal renal function.

Clinical Uses: Foscarnet is used for patients with CMV retinitis and acyclovir-resistant HSV infection Foscarnet has also been used to treat CMV colitis and esophagitis and acyclovir- resistant VZV infection.

Adverse Reactions: The potential adverse effects include renal insufficiency, hypocalcemia or hypercalcemia, and hypo- or hyperphosphatemia. Genital ulcerations associated with foscarnet therapy may be due to high levels of ionized drug in the urine. Central nervous system toxicities include hallucinations, and seizures.