II. Indications

  1. Cytomegalovirus Retinitis (HIV Infection)
  2. HSV Infection (Acyclovir-resistant) in Immunocompromised patients
    1. Also used for Acyclovir-resistant VZV (off-label)

III. Contraindications

  1. Children (relative contraindication)
    1. May be used if benefit outweighs risk

IV. Mechanism

  1. Synthetic analog of inorganic pyrophosphate
  2. Selectively blocks viral DNA Polymerases at their pyrophosphate binding site, preventing DNA Replication
  3. Crosses the blood brain barrier

V. Dosing

  1. Prehydrate before Foscarnet infusion
    1. Normal Saline 750 to 1000 ml for doses 90 to 120 mg/kg
    2. Normal Saline 500 ml for doses 40 to 60 mg/kg
  2. Cytomegalovirus Retinitis
    1. First 2 to 3 weeks
      1. Give 60 mg/kg IV over 1 hour every 8 hours OR
      2. Give 90 mg/kg IV over 1.5 to 2 hours every 12 hours
    2. Next
      1. Give 90 to 120 mg/kg IV over 2 hours daily
  3. HSV Infection (Acyclovir-resistant)
    1. Give 40 mg/kg IV over 1 hour (no faster than 1 mg/kg/min) every 8 to 12 hours for 2 to 3 weeks

VI. Adverse Effects

  1. Less well tolerated than Ganciclovir
  2. Nephrotoxicity
    1. Typically resolves on stopping medication, but Hemodialysis has been needed for some patients
  3. Anemia
  4. Granulocytopenia
  5. Phlebitis
  6. Nausea or Vomiting
  7. Genital Ulcers
    1. Ulcers secondary to local urine irritation
  8. Tooth deposits
    1. Seen in young animals
  9. Electrolyte abnormalities
    1. Foscarnet contains high Sodium concentration (10 meq or 460 mg per mg Foscarnet)
    2. Hypocalcemia, Hypomagnesemia and Hypokalemia
    3. Avoid rapid infusion (risk of secondary QTc Prolongation, Seizures)

VII. Safety

  1. Unknown safety in pregnancy
  2. Unknown safety in Lactation

VIII. Drug Interactions

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Ontology: Foscarnet (C0070895)

Definition (NCI) A synthetic organic analog of inorganic pyrophosphate with activity against several types of viruses, but primarily used for the treatment of cytomegalovirus retinitis. Foscarnet selectively blocks the pyrophosphate binding site of virus-specific DNA polymerases at concentrations that do not affect cellular DNA polymerases. Because this agent crosses the blood brain barrier, it may be used in the treatment of viral infections of the central nervous system.
Definition (MSH) An antiviral agent used in the treatment of cytomegalovirus retinitis. Foscarnet also shows activity against human herpesviruses and HIV.
Definition (CSP) phosphonoformate (trisodium); anticytomegaloviral agent with potential for treating AIDS retinopathy.
Concepts Pharmacologic Substance (T121) , Organophosphorus Compound (T115)
MSH D017245
SnomedCT 372902006, 96099004
LNC LP15700-5, MTHU012422
English Phosphonoformic Acid, Phosphinecarboxylic acid, dihydroxy-, oxide, Carboxyphosphonic Acid, Foscarnet [Chemical/Ingredient], Phgosphonocarboxylic Acid, Foscarnet, foscarnet, Foscarnet (product), Foscarnet (substance), phosphonoformic acid, FOSCARNET
Swedish Foskarnet
Czech foskarnet
Finnish Foskarnetti
Russian FOSFONOMURAV'INAIA KISLOTA, FOSFONOFORMIAT, FOSKARNET, FOSFONEFIR MURAV'INOI KISLOTY, ФОСКАРНЕТ, ФОСФОНОМУРАВЬИНАЯ КИСЛОТА, ФОСФОНОФОРМИАТ, ФОСФОНЭФИР МУРАВЬИНОЙ КИСЛОТЫ
Japanese ホスホノギ酸, ホスカビル, ホスカルネットナトリウム, ホスホノギ酸塩, ホスホノホルミック酸, ホスカルネット, ホスホノホルミック酸塩, ホスホノホルメート, ホスカルネットナトリウム水和物, フォスカルネット, フォスカビル, ホスホノホルム酸
Italian Acido fosfonoformico, Foscarnet
French Acide phosphono-formique, Acide phosphonoformique, Foscarnet
Polish Foskarnet, Fosfonomrówczan, Kwas fosfonomrówkowy
Spanish Fosfonoformato, foscarnet (producto), foscarnet (sustancia), foscarnet, Foscarnet, Ácido Fosfonofórmico
German Foscarnet, Phosphonoameisensäure
Portuguese Foscarnet, Ácido Fosfonofórmico