Generic Name: foscarnet

Brand and Other Names: Foscavir, Phosphonoformic acid

Drug Class: Antivirals, CMV; Antivirals, Other

What is foscarnet, and what is it used for?

Foscarnet is a prescription medication used for the treatment of cytomegalovirus (CMV) eye infections (CMV retinitis) in patients with AIDS. It is also used to treat herpes simplex in patients with acyclovir resistance who are immunocompromised.

Warnings

Contraindications

  • Hypersensitivity

Effects of drug abuse

  • None

Short-Term Effects

  • See “What are the side effects of foscarnet?”

Long-Term Effects

  • See “What are the side effects of foscarnet?”

Cautions

  • Caution with renal impairment
  • Do not administer by rapid or bolus IV injection; use infusion pump
  • May be associated with changes in serum electrolytes changes including hypocalcemia, hypo- or hyperphosphatemia, hypomagnesemia, or hypokalemia
  • Serious acute hypersensitivity reactions (e.g., anaphylactic shock, urticaria, angioedema) reported; if such acute reactions occur, discontinue therapy; and institute appropriate medical therapy immediately
  • Cases of status epilepticus reported; several cases of seizures associated with death; electrolyte abnormalities may increase risk of seizures
  • Associated with prolongation of QT interval, an ECG abnormality that has been associated with torsades de pointes, reported during postmarketing surveillance; has occurred with confounding risk factors such as underlying cardiac disease, electrolyte abnormalities and other concomitant medications; use caution in patients with history of QT prolongation, taking medications known to prolong the QT interval, patients with electrolyte disturbances, or patients who have other risk factors for QT prolongation; electrocardiograms (ECGs) and measurement of electrolytes should be obtained prior to treatment initiation and periodically during treatment
  • Due to sodium content of foscarnet (240 micromoles (5.5 mg) of sodium per mL); avoid foscarnet use when IV infusion of large amount of sodium or water may not be tolerated (e.g. in patients with cardiomyopathy); avoid foscarnet use in patients on a controlled sodium diet

What are the side effects of foscarnet?

Common side effects of foscarnet include:

Serious side effects of foscarnet include:

Rare side effects of foscarnet include:

  • none

Seek medical care or call 911 at once if you have the following serious side effects:

This is not a complete list of side effects and other serious side effects or health problems that may occur because of the use of this drug.

Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

SLIDESHOW

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What are dosages of foscarnet?

Adult dosage

Injectable solution

  • 2.4 g/100 mL

CMV Retinitis

Adult dosage

  • Induction: 60 mg/kg every 8 hours IV x14-21 days; infuse IV over at least 60 min  
  • Maintenance: 90-120 mg/kg IV every day; infuse IV over at least 60-90 min

Herpes Simplex

Adult dosage

  • Option 1: 40 mg/kg IV every 8 hours  x14-21 days; infuse IV over at least 60 min  
  • Option 2: 40-60 mg/kg IV every 12 hours x14-21 days; infuse IV over at least 60 min

What other drugs interact with foscarnet?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first

  • Foscarnet has severe interactions with no other drugs.
  • Foscarnet has serious interactions with at least 63 other drugs.
  • Foscarnet has moderate interactions at least 105 other drugs.
  • Foscarnet has minor interactions with at least 30 other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. 

Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your healthcare professional or doctor for additional medical advice, or if you have health questions or concerns.

Pregnancy and breastfeeding

Pregnancy

  • Use with caution if benefits outweigh risks during pregnancy

Breastfeeding

Summary

Foscarnet is a prescription medication used for the treatment of cytomegalovirus (CMV) eye infections (CMV retinitis) in patients with AIDS. It is also used to treat herpes simplex in patients with acyclovir resistance who are immunocompromised. Common side effects of foscarnet include fever, flu-like symptoms, nausea, vomiting, diarrhea, chest pain, back pain, and headache. Do not take if you have drug hypersensitivity or are breastfeeding. Use with caution if you have renal impairment.

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Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Medically Reviewed on 10/27/2022
References
REFERENCES

https://reference.medscape.com/drug/foscavir-phosphonoformic-acid-foscarnet-342614