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foscarnet

Generic Name: foscarnet (fos KAR net)
Brand Name: Foscavir

What is foscarnet?

Foscarnet is an antiviral medicine that prevents certain virus cells from multiplying in your body.

Foscarnet is used to treat cytomegalovirus (CMV) retinitis in people with AIDS.

Foscarnet is also used to treat herpes simplex virus (HSV) in people with a weak immune system. Foscarnet is usually given for HSV after other antiviral medications have been tried without successful treatment.

Foscarnet is not a cure for CMV or HSV, and your virus may progress during or after treatment.

Foscarnet may also be used for purposes not listed in this medication guide.

What is the most important information I should know about foscarnet?

Foscarnet can harm your kidneys. This effect is increased when you also use certain other medicines, including: antivirals, chemotherapy, injected antibiotics, medicine for bowel disorders, medicine to prevent organ transplant rejection, injectable osteoporosis medication, and some pain or arthritis medicines (including aspirin, Tylenol, Advil, and Aleve).

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Your kidney function and electrolytes (potassium, sodium, magnesium, phosphorus) will need to be tested often.

Injecting foscarnet too fast can cause dangerous or unwanted side effects.

What should I discuss with my health care provider before using foscarnet?

You should not use foscarnet if you are allergic to it.

To make sure foscarnet is safe for you, tell your doctor if you have:

  • kidney disease;

  • heart disease;

  • an electrolyte imbalance (such as low levels of calcium, potassium, or magnesium in your blood);

  • epilepsy or other seizure disorder; or

  • if you are on a low salt diet.

It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

It is not known whether foscarnet passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

How is foscarnet given?

Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not use this medicine in larger or smaller amounts or for longer than recommended.

Foscarnet is injected into a vein through an IV using an infusion pump. The medicine enters the body through a catheter placed into the vein. A healthcare provider will show you how to use an infusion pump. Do not self-inject foscarnet if you do not understand how to give the injection and properly dispose of used needles, IV tubing, and other items used to inject the medicine.

You may also be given IV fluids to keep you from getting dehydrated.

You may need to mix foscarnet with a liquid (diluent) before using it. If you are using the injections at home, be sure you understand how to properly mix and store the medicine. Do not give foscarnet with other medicines in the same IV line.

Foscarnet should be clear and colorless. Do not use the medicine if it has changed colors or has any particles in it. Call your doctor for a new prescription.

The medicine must be injected slowly and can take up to 2 hours to complete. Injecting foscarnet too fast can cause dangerous or unwanted side effects.

Foscarnet is usually given for 2 to 3 weeks. Follow your doctor's dosing instructions very carefully.

While using foscarnet, your kidney function and electrolytes (potassium, sodium, magnesium, phosphorus) will need to be tested often, and you may also need regular eye exams.

Store foscarnet at room temperature away from very hot or very cold temperature.

What happens if I miss a dose?

Call your doctor for instructions if you miss a dose of foscarnet.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include severe forms of some of the side effects listed in this medication guide.

What should I avoid while using foscarnet?

Avoid getting this medicine in your eyes, as it may cause burning or irritation. If it does get into your eyes rinse with water and call your doctor.

Foscarnet side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • pain or burning when you urinate;

  • a seizure (convulsions);

  • low white blood cell counts--fever, swollen gums, painful mouth sores, pain when swallowing, skin sores, cold or flu symptoms, cough, trouble breathing;

  • low red blood cells (anemia)--pale skin, feeling light-headed or short of breath, rapid heart rate, trouble concentrating;

  • low calcium--numbness or tingly feeling around your mouth, fast or slow heart rate, muscle tightness or contraction, overactive reflexes;

  • low potassium--constipation, numbness or tingling, tiredness, muscle weakness, slow heart rate, fainting; or

  • kidney problems--little or no urinating; painful or difficult urination; swelling in your feet or ankles; feeling tired or short of breath.

Some of this medicine leaves the body in urine, which can cause irritation when you urinate. You may also develop sores or ulcers around your urethra (the opening where urine passes out of your bladder). Drink plenty of fluids and take care to keep your genital area clean while receiving this medicine.

Common side effects may include:

  • nausea, vomiting, diarrhea; or

  • headache.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

Foscarnet dosing information

Usual Adult Dose for CMV Retinitis:

Induction therapy: 90 mg/kg IV (90- to 120-minute infusion) every 12 hours or 60 mg/kg IV (minimum 1-hour infusion) every 8 hours over 2 to 3 weeks depending on clinical response
Maintenance therapy: 90 to 120 mg/kg IV (2-hour infusion) once a day

Comments:
-Maintenance therapy dose should be individualized for renal function.
-Most patients should be started on maintenance therapy at 90 mg/kg/day; escalation to 120 mg/kg/day may be considered should early reinduction be required due to retinitis progression.
-Some patients who show excellent tolerance to this drug may benefit from starting maintenance therapy at 120 mg/kg/day earlier in their treatment.
-Patients who have retinitis progression during foscarnet maintenance therapy may be retreated with the induction and maintenance regimens in combination with ganciclovir; this drug must not be mixed with ganciclovir due to physical incompatibility.

Uses: For the treatment of CMV retinitis in patients with AIDS; in combination with ganciclovir for patients who relapse after monotherapy with either drug

US CDC, National Institutes of Health (NIH), and Infectious Diseases Society of America (IDSA) Recommendations for HIV-infected Patients:
For sight-threatening lesions (adjacent to optic nerve or fovea):
-Intravitreal injections: 2.4 mg as an intravitreal injection for 1 to 4 doses over 7 to 10 days
-Systemic therapy: 60 mg/kg IV every 8 hours or 90 mg/kg IV every 12 hours for 14 to 21 days, then 90 to 120 mg/kg IV every 24 hours

For peripheral lesions: 60 mg/kg IV every 8 hours or 90 mg/kg IV every 12 hours for 14 to 21 days, then 90 to 120 mg/kg IV every 24 hours

Chronic maintenance therapy (secondary prophylaxis): 90 to 120 mg/kg IV once a day

Comments:
-Intravitreal injections plus a systemic antiviral agent should be used for sight-threatening lesions.
-Recommended as alternative systemic therapy

Usual Adult Dose for Herpes Simplex -- Mucocutaneous/Immunocompromised Host:

Induction therapy: 40 mg/kg IV (minimum 1-hour infusion) every 8 or 12 hours
Duration of therapy: 2 to 3 weeks or until healed

Use: For the treatment of acyclovir-resistant mucocutaneous herpes simplex virus (HSV) infections in immunocompromised patients

US CDC, NIH, and IDSA recommendations for the treatment of acyclovir-resistant mucocutaneous HSV infections in HIV-infected patients: 80 to 120 mg/kg/day IV in 2 to 3 divided doses
Duration of therapy: Until clinical response

Comments:
-Recommended as preferred therapy

Usual Adult Dose for CMV Gastroenteritis:

US CDC, NIH, and IDSA recommendations for the treatment of CMV esophagitis or colitis in HIV-infected patients: 60 mg/kg IV every 8 hours or 90 mg/kg IV every 12 hours
Duration of therapy: 21 to 42 days or until signs/symptoms resolve

Comments:
-Recommended as alternative therapy
-Recommended for patients with therapy-limiting toxicities to ganciclovir or with ganciclovir resistance
-Maintenance therapy usually not needed but should be considered after relapses.

Usual Adult Dose for Varicella-Zoster:

US CDC, NIH, and IDSA recommendations for progressive outer retinal necrosis in HIV-infected patients:
-Intravitreal: 1.2 mg/0.05 mL intravitreal twice a week
-IV: 90 mg/kg IV every 12 hours

Comments:
-Ganciclovir IV and/or foscarnet IV PLUS ganciclovir intravitreal and/or foscarnet intravitreal recommended.
-An experienced ophthalmologist should be involved.

Usual Pediatric Dose for CMV Retinitis:

US CDC, NIH, IDSA, Pediatric Infectious Diseases Society (PIDS), and American Academy of Pediatrics (AAP) Recommendations for HIV-exposed and HIV-infected Children:
Induction therapy: 60 mg/kg IV every 8 hours or 90 mg/kg IV every 12 hours
Duration of therapy:
-CNS disease: Until symptomatic improvement
-Disseminated disease and retinitis: 14 to 21 days

Chronic suppressive therapy/secondary prophylaxis: 90 to 120 mg/kg IV once a day

US CDC, NIH, and IDSA Recommendations for HIV-infected Adolescents:
For sight-threatening lesions (adjacent to optic nerve or fovea):
-Intravitreal injections: 2.4 mg as an intravitreal injection for 1 to 4 doses over 7 to 10 days
-Systemic therapy: 60 mg/kg IV every 8 hours or 90 mg/kg IV every 12 hours for 14 to 21 days, then 90 to 120 mg/kg IV every 24 hours

For peripheral lesions: 60 mg/kg IV every 8 hours or 90 mg/kg IV every 12 hours for 14 to 21 days, then 90 to 120 mg/kg IV every 24 hours

Chronic maintenance therapy (secondary prophylaxis): 90 to 120 mg/kg IV once a day

Comments:
-In combination with ganciclovir, recommended as first choice for CNS disease in children
-Recommended as alternative therapy for disseminated disease and retinitis in children
-In combination with ganciclovir, recommended as an alternative for retinitis in children; ganciclovir IV plus foscarnet IV may be considered as induction therapy in children with sight-threatening disease or for treatment after failure/relapse on monotherapy.
-Recommended as a first choice for secondary prophylaxis in children
-Induction therapy should be followed by chronic suppressive therapy in children.
-Intravitreal injections plus a systemic antiviral agent should be used for sight-threatening lesions in adolescents.
-Recommended as alternative systemic therapy in adolescents

Usual Pediatric Dose for Herpes Simplex -- Mucocutaneous/Immunocompromised Host:

Acyclovir-resistant infection:
-US CDC, NIH, IDSA, PIDS, and AAP recommendations for HIV-exposed and HIV-infected children: 40 mg/kg IV 3 times a day or 60 mg/kg IV twice a day
-US CDC, NIH, and IDSA recommendations for HIV-infected adolescents: 80 to 120 mg/kg/day IV in 2 to 3 divided doses until clinical response

Comments:
-Recommended as preferred therapy for acyclovir-resistant infections
-Should be infused slowly over 2 hours in children

Usual Pediatric Dose for CMV Gastroenteritis:

US CDC, NIH, and IDSA recommendations for the treatment of CMV esophagitis or colitis in HIV-infected adolescents: 60 mg/kg IV every 8 hours or 90 mg/kg IV every 12 hours
Duration of therapy: 21 to 42 days or until signs/symptoms resolve

Comments:
-Recommended as alternative therapy
-Recommended for patients with therapy-limiting toxicities to ganciclovir or with ganciclovir resistance
-Maintenance therapy usually not needed but should be considered after relapses.

Usual Pediatric Dose for Varicella-Zoster:

US CDC, NIH, IDSA, PIDS, and AAP Recommendations for HIV-exposed and HIV-infected Children:
Acyclovir-resistant varicella-zoster virus (VZV): 40 to 60 mg/kg IV every 8 hours
Duration of therapy: 7 days or until no new lesions appear for at least 48 hours

Progressive outer retinal necrosis:
-Intravitreal: 1.2 mg/0.05 mL intravitreal twice a week
-IV: 90 mg/kg IV every 12 hours

US CDC, NIH, and IDSA Recommendations for Progressive Outer Retinal Necrosis in HIV-infected Adolescents:
-Intravitreal: 1.2 mg/0.05 mL intravitreal twice a week
-IV: 90 mg/kg IV every 12 hours

Comments:
-Recommended as treatment of choice for acyclovir-resistant VZV
-Ganciclovir IV PLUS foscarnet IV PLUS ganciclovir intravitreal and/or foscarnet intravitreal recommended as first choice for progressive outer retinal necrosis in children.
-Ganciclovir IV and/or foscarnet IV PLUS ganciclovir intravitreal and/or foscarnet intravitreal recommended for progressive outer retinal necrosis in adolescents.
-An experienced ophthalmologist should be involved.

What other drugs will affect foscarnet?

Foscarnet can harm your kidneys. This effect is increased when you also use certain other medicines, including: antivirals, chemotherapy, injected antibiotics, medicine for bowel disorders, medicine to prevent organ transplant rejection, injectable osteoporosis medication, and some pain or arthritis medicines (including aspirin, Tylenol, Advil, and Aleve).

Tell your doctor about all your current medicines and any you start or stop using, especially:

  • pentamidine;

  • ritonavir (Norvir, Kaletra); or

  • saquinavir (Invirase).

This list is not complete. Other drugs may interact with foscarnet, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Where can I get more information?

  • Your pharmacist can provide more information about foscarnet.
  • Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
  • Disclaimer: Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.

Copyright 1996-2012 Cerner Multum, Inc. Version: 3.01. Revision Date: 2015-02-16, 7:19:05 AM.

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