Foscarnet Injection

WHY is this medicine prescribed?

Foscarnet injection is used alone or with ganciclovir (Cytovene) to treat cytomegalovirus (CMV) retinitis (an eye infection that can cause blindness) in people who have human immunodeficiency virus (HIV) infection. Foscarnet injection is also used to treat herpes simplex virus (HSV) infections of the skin and mucus membranes (mouth, anus) in people whose immune system is not working normally and when treatment with acyclovir did not help. Foscarnet is in a class of medications called antivirals. It works by slowing the growth of CMV and HSV. Foscarnet controls CMV retinitis and HSV infections of the skin and mucus membranes but does not cure these infections.

HOW should this medicine be used?

Foscarnet injection comes as a liquid to be intravenously (into a vein). It is usually infused slowly over 1 to 2 hours every 8 or 12 hours. The length of your treatment depends on how you respond to the medication.

You may receive foscarnet injection in a hospital or you may administer the medication at home. If you will be receiving foscarnet injection at home, your healthcare provider will show you how to use the medication. Be sure that you understand these directions, and ask your healthcare provider if you have any questions

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Are there OTHER USES for this medicine?

Foscarnet injection is also sometimes used to treat and prevent CMV infections in patients with human immunodeficiency virus (HIV). Talk to your doctor about the risks of using this medication for your condition.

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What SPECIAL PRECAUTIONS should I follow?

Before using foscarnet injection,

• tell your doctor and pharmacist if you are allergic to foscarnet, any other medications, or any of the ingredients in foscarnet injection. Ask your pharmacist for a list of the ingredients.
• Tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take while receiving foscarnet injection. Your doctor may need to change the doses of your medications or monitor you carefully for side effects..
• tell your doctor if you have or have ever had QT prolongation (an irregular heart rhythm that can lead to fainting, loss of consciousness, seizures, or sudden death); low levels of potassium or magnesium in your blood; heart disease; or if you are on a low salt diet.
• tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. If you become pregnant while receiving foscarnet injection, call your doctor.
• you should know that foscarnet may make you drowsy or dizzy. Do not drive a car or operate machinery until you know how this medication affects you.

What SPECIAL DIETARY instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

What SIDE EFFECTS can this medicine cause?

Foscarnet may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• itching, redness, pain, or swelling in the place where you received your injection
• nausea
• stomach pain
• back pain
• loss of appetite or weight
• constipation
• headache
• vision changes
• redness, irritation, or sores on the penis
• redness, irritation, or sores around the vagina

Some side effects can be serious. If you experience any of these symptoms or those listed in the IMPORTANT WARNING section, call your doctor immediately or get emergency medical treatment:

• rash
• hives
• swelling of the eyes, face, lips, tongue, or throat
• difficulty breathing or swallowing
• chest pain
• fast, pounding, or irregular heartbeat
• fainting
• lightheadedness
• loss of consciousness
• vomiting
• diarrhea
• fever, chills, cough, or other signs of infection
• unusual bleeding or bruising
• black and tarry stools
• bloody vomit or vomited material that looks like coffee grounds
• pale skin
• shortness of breath
• confusion
• muscle pain or cramps
• increased sweating

Foscarnet may cause other side effects. Call your doctor if you have any unusual problems while using this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (https://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

What should I do in case of OVERDOSE?

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

Symptoms of overdose may include the following:

• seizures
• numbness or tingling around the mouth or in fingers or toes
• decreased urination
• swelling of the face, arms, hands, feet, ankles, or lower legs
• unusual tiredness or weakness

What OTHER INFORMATION should I know?

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.

The American Society of Health-System Pharmacists, Inc. represents that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information is not a substitute for medical care.

AHFS^® Patient Medication Information™. © Copyright, 2024. The American Society of Health-System Pharmacists^®, 4500 East-West Highway, Suite 900, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.

Selected Revisions: June 20, 2024.