What is Foscarnet?
Foscarnet is an antiviral medication 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 other purposes not listed in this medication guide.
What is the most important information I should know about Foscarnet?
Before using foscarnet, tell your doctor if you have kidney disease, a seizure disorder, heart disease, a nerve disorder, or an electrolyte imbalance such as low calcium, potassium, or magnesium.
To be sure this medication is not causing harmful effects, your blood will need to be tested on a regular basis. Your kidney function may also need to be tested, and you may also need regular eye exams. Do not miss any scheduled visits to your doctor.
Stop using foscarnet and call your doctor at once if you urinate less than usual or not at all, or if you have numbness or tingling around your mouth, uncontrolled muscle movements, or pain or burning when you urinate.
Foscarnet can be harmful to the kidneys, and these effects are increased when foscarnet is used together with other medicines that can harm the kidneys. Before using foscarnet, tell your doctor about all other medications you use. Many other drugs (including some over-the-counter medicines) can be harmful to the kidneys.
Foscarnet is not a cure for CMV or HSV, and your virus may progress during or after treatment.
What should I discuss with my healthcare provider before taking Foscarnet?
You should not use this medication if you are allergic to foscarnet.
If you have any of these other conditions, you may need a dose adjustment or special tests to safely use this medication:
- kidney disease
- epilepsy or other seizure disorder
- a history of head injury or brain tumor
- heart disease
- a nerve disorder
- low levels of calcium, magnesium, or potassium in your blood; or
- any other type of electrolyte imbalance
FDA pregnancy category C. It is not known whether foscarnet is harmful to an unborn baby. Before taking this medication, tell your doctor if you are pregnant or plan to become pregnant during treatment.
It is not known whether foscarnet passes into breast milk or if it could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.
Foscarnet Side Effects
What are the possible side effects of Foscarnet?
Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Stop using foscarnet and call your doctor at once if you have any of these serious side effects:
- urinating less than usual or not at all
- drowsiness, confusion, mood changes, increased thirst, loss of appetite, nausea and vomiting
- swelling, weight gain, feeling short of breath
- numbness or tingling around your mouth or in your hands or feet
- dry mouth, increased thirst, restless feeling, increased urination, muscle pain or weakness, fainting, or seizure (convulsions)
- fever, chills, body aches, flu symptoms
- pale skin, feeling light-headed, rapid heart rate, trouble concentrating; or
- restless muscle movements in your eyes, tongue, jaw, or neck
- trouble breathing; or
- pain or burning when you urinate
Less serious side effects may include:
- anxiety, depressed mood
- stomach pain
- headache, dizziness
- cough
- increased sweating
- skin rash
- problems with vision
- tired feeling
- joint or muscle pain; or
- pain or swelling where the injection was given
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.
Foscarnet Interactions
What other drugs affect Foscarnet?
Foscarnet can harm your kidneys. This effect is increased when you also use certain other medicines that can harm the kidneys. You may need dose adjustments or special tests when using any of these medications together with foscarnet.
- amphotericin B (Abcelet, Ambisome)
- pentamidine (Nebupent, Pentam)
- antiviral medications
- any injected antibiotics
- medicines to treat a bowel disorder
- medication to prevent organ transplant rejection
- pain or arthritis medicines; or
- HIV or AIDS medications such as ritonavir (Norvir) or saquinavir (Invirase)
This list is not complete and there may be other drugs that can interact with foscarnet. Tell your doctor about all your prescription and over-the-counter medications, vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start a new medication without telling your doctor.
What should I avoid while taking 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 Dosage
How should I take Foscarnet?
Foscarnet is given as an injection through a needle placed into a vein. The medicine must be given slowly through an IV infusion pump, and can take up to 2 hours to complete.
You may be given instructions on how to inject your medicine at home. Do not use this medicine at home if you do not fully understand how to give the injection and properly dispose of needles and other items used in giving the medicine.
With each foscarnet injection, you may be given IV fluids to keep you from getting dehydrated.
Foscarnet is usually given for 2 to 3 weeks. Your doctor may occasionally change your dose to make sure you get the best results from this medication.
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 medication. Do not give foscarnet with other medications in the same IV line.
Foscarnet should be clear and colorless. Do not use the medication if it has changed colors or has any particles in it. Call your doctor for a new prescription.
To be sure this medication is not causing harmful effects, your blood will need to be tested on a regular basis. Your kidney function may also need to be tested, and you may also need regular eye exams. Do not miss any scheduled visits to your doctor.
Store foscarnet at room temperature away from very hot or very cold temperature.
What happens if I overdose on Foscarnet?
Seek emergency medical attention if you think you have used too much of this medicine.
Overdose symptoms may include numbness or tingling, thirst, drowsiness, confusion, urinating more or less than usual, muscle pain or weakness, fast heart rate, feeling light-headed, fainting, or seizure (convulsions).
What happens if I miss a dose of Foscarnet?
Use the medication as soon as you remember the missed dose. If it is almost time for your next dose, skip the missed dose and use the medicine at your next regularly scheduled time. Do not use extra medicine to make up the missed dose.
Sourced from everydayhealth.com