Drug Database: Foscarnet Sodium

What is foscarnet sodium?

Foscarnet sodium is an antiviral prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the treatment of cytomegalovirus (CMV) retinitis in individuals with AIDS. Foscarnet sodium is also FDA-approved for the treatment of a certain type of herpes simplex virus (HSV) infection, called acyclovir-resistant mucocutaneous HSV infection, in people with weakened immune systems.

CMV diseases—such as those affecting the eye (retinitis)—and HSV diseases can be opportunistic infections (OIs) of HIV. An OI is an infection that occurs more frequently or is more severe in people with weakened immune systems—such as people with HIV—than in people with healthy immune systems. To learn more about OIs, read the HIVinfo What is an Opportunistic Infection? fact sheet.

How is foscarnet sodium used in people with HIV?

The Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents with HIV and the Guidelines for the Prevention and Treatment of Opportunistic Infections in Children with and Exposed to HIV include recommendations on the uses of foscarnet sodium in people with HIV to:

Treat: 

• CMV diseases, including the following:
  • CMV retinitis
  • CMV colitis
  • CMV esophagitis (infection and inflammation of the esophagus)
  • CMV pneumonitis (infection and inflammation of the lungs)
  • CMV neurological disease (infection and disease of the nervous system)
• Acyclovir-resistant mucocutaneous HSV infection
• Certain types of varicella zoster virus (VZV) disease, including progressive outer retinal necrosis and VZV infections that are resistant to treatment with the drug acyclovir. 

Prevent: 

• CMV retinitis from recurring

The recommended uses may not always be consistent with FDA-approved uses of foscarnet sodium. See the Adult and Pediatric guidelines for complete information on recommended uses of foscarnet sodium in adults and children with HIV. Foscarnet sodium may have other recommended uses not listed above. 

What should I tell my health care provider before using foscarnet sodium?

Before using foscarnet sodium, tell your health care provider:

• If you are allergic to foscarnet sodium or any other medicines.
• About any medical conditions you have or have had, including:
  • Kidney or liver problems
  • Mineral or electrolyte imbalance, such as low levels of calcium, magnesium, or potassium and low or high levels of phosphate
  • Seizures
  • Heart disease and heart rhythm problems
• If you are on a low sodium (salt) diet.
• About any health conditions that may prevent you from receiving medicine by injection or infusion.
• If you are pregnant or plan to become pregnant. Foscarnet sodium should be used during pregnancy only if clearly needed. Talk to your health care provider about the risks and benefits of using foscarnet sodium during pregnancy.
• If you are breast/chestfeeding or plan to breast/chestfeed. For people with HIV in the United States, the Guideline recommends speaking with your health care provider to discuss options for feeding your baby. People with suppressed viral load have a less than 1% chance of transmitting HIV to their baby via their own milk.
• About other prescription and nonprescription medicines, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Foscarnet sodium may affect the way other medicines or products work, and other medicines or products may affect how foscarnet sodium works. Ask your health care provider if there are interactions between foscarnet sodium and the other medicines you take.

Ask your health care provider about possible side effects from foscarnet sodium. Your health care provider will tell you what to do if you have side effects.

How should I use foscarnet sodium?

Use foscarnet sodium according to your health care provider’s instructions. Your health care provider will tell you how much foscarnet sodium to use and when to use it. Before you start foscarnet sodium and each time you get a refill, read any printed information that comes with your medicine.

How should foscarnet sodium be stored?

• Store foscarnet sodium injection at room temperature, 68°F to 77°F (20°C to 25°C), and protect it from excessive heat and from freezing.
• Keep foscarnet sodium in the container that it came in and keep the container tightly closed.
• Do not use foscarnet sodium if the original seal over the container opening is broken or missing.
• Throw away foscarnet sodium that is no longer needed or expired (out of date). Follow FDA guidelines on how to safely dispose of unused medicine.
• Keep foscarnet sodium and all medicines out of reach of children.

Where can I find more information about foscarnet sodium?

• Recommendations on the HIV-related uses of foscarnet sodium, from the Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents with HIV and the Guidelines for the Prevention and Treatment of Opportunistic Infections in Children with and Exposed to HIV.
• This Patient Version drug summary is based on the following FDA label(s): Injection (solution).
• The American Hospital Formulary Service (AHFS) Patient Medication Information for foscarnet injection available from MedlinePlus.
• Foscarnet sodium-related research studies, from ClinicalTrials.gov. (The ClinicalTrials.gov search can be modified so that you can get results that better match your interests. To learn more about the ClinicalTrials.gov search features, please see How to Search.)