foscarnet (Foscavir)
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Introduction
Tradename: Foscavir. A virustatic agent.
Indications
- CMV retinitis:
- indications a patients with ganciclovir-resistant CMV
- patients who cannot tolerate ganciclovir
- induction therapy
- 60 mg/kg every 8 hours or 90 mg/kg every 12 hours IV for 2-3 weeks
- maintenance therapy: 90-120 mg/kg/day
- foscarnet is administered IV as a 1-2 hour infusion
- daily infusions of normal saline (1 liter) may reduce nephrotoxicity
- Varicella zoster[5]
- Herpes simplex
Dosage
Injection: 24 mg/mL (250 mL, 500 mL)
Dosage adjustment in renal failure
(maintenance)
- 25 mg/kg every 8 hours GFR > 50 mL/min
- 15 mg/kg every 8 hours GFR 10-50 mL/min
- 6 mg/kg every 8 hours GFR < 10 mL/min
Pharmacokinetics
elimination via kidney
Adverse effects
- common (> 10%)
- less common (1-10%)
- fevers, rigors, asthenia, malaise, pain at site of injection, sepsis, paresthesias, dizziness, involuntary muscle contractions, hypoesthesia, neuropathy, anorexia, granulocytopenia, leukopenia, electrolyte disorder, depression, confusion, anxiety, coughing, dyspnea, rash, increased sweating, visual disturbance
- uncommon (< 1%)
- other[4]
- hypocalcemia (decreased ionized calcium)
- hypomagnesemia
- hypophosphatemia
Test interactions
- decreased serum gonadotropins
Mechanism of action
- pyrophosphate that inhibits Herpesvirus DNA polymerase
- does NOT require intracellular phosphorylation for activity
- active against viruses deficient in thymidine kinase
More general terms
References
- ↑ The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
- ↑ Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 294
- ↑ Kaiser Permanente Northern California Regional Drug Formulary, 1998
- ↑ 4.0 4.1 Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
- ↑ 5.0 5.1 Deprecated Reference
- ↑ Department of Veterans Affairs, VA National Formulary