- Inhibits viral DNA polymerase, RNA. polymerase,
HIV reverse transcriptase. Phosphorylation step
not required for drug activation.
- In vitro activity against HSV, VZV, HIV,
hepatitis B. virus, HHV-6,Epstein-Barr virus, and CMV.
- Foscarnet resistance: DNA polymerase gene
point mutation, typically following prolonged
administration; mutations may also occur in HIV-1
reverse transcriptase
- Only
available by IV route of administration.
- Clearance: primarily renal; dosage
adjustment required based on creatinine
clearance.
Foscarnet: Clinical Use
- CMV retinitis, acyclovir-resistant HSV;
- Foscarnet is as effective as ganciclovir
in treating CMV retinitis in patients with AIDS;
however, patients survived longer, perhaps
because of foscarnet's anti-HIV activity.
- foscarnet superior to vidarabine in
treatment of acyclovir-resistant human simplex
viral infections
Forcarnet: Adverse
Reactions
- Significant renal side effects: real
insufficiency, hypocalcemia, hypercalcemia,
hypophosphatemia, hyperphosphatemia,
hypomagnesemia (these effects are due to
foscarnet's ability to bind divalent ions).
- Lack of hematologic abnormalities allows
foscarnet use in combination with
myelosuppressive agents such as zidovudine.
- Slow infusion rates and saline hydration
protect against nephrotoxicity and electrolyte
imbalances.
- Genital ulcerations
- CNS toxicities: headache, seizures,
hallucinations
- Coadministration with pentamidine
increases hypocalcemia and renal toxicity
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