Foscarnet sodium-injection

See also Warning section.Because this medication is used in patients who use other medications, it is difficult to tell which side effects are caused by foscarnet. Nausea, vomiting, headache, diarrhea, dizziness, loss of appetite, and increased sweating have been reported. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell your doctor immediately if any of these unlikely but serious side effects occur: mental/mood changes (e.g., depression, anxiety), new vision problems, muscle cramps/spasms, weakness, fast breathing, irregular heartbeat, change in the amount of urine, painful urination, vaginal sores, seizures, fever, persistent sore throat.You may experience redness, irritation, or pain at the injection site. Tell your doctor if this occurs. Also tell your doctor if you experience tingling or numbness of the hands or feet, or tingling around your mouth during or after the infusion. Your doctor may need to adjust your dose.A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

If overdose is suspected, contact a poison control center or emergency room immediately. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: seizures, tingling around the mouth, numbness/tingling in arms/legs.

It is important to use this medication as scheduled. If you miss a dose, contact your doctor immediately to set up a new dosing schedule. Do not double the dose to catch up.

In controlled clinical trials performed in the United States, overdosage with FOSCAVIR was reported in 10 out of 189 patients. All 10 patients experienced adverse events and all except one made a complete recovery. One patient died after receiving a total daily dose of 12.5 g for three days instead of the intended 10.9 g. The patient suffered a grand mal seizure and became comatose. Three days later the patient expired with the cause of death listed as respiratory/cardiac arrest. The other nine patients received doses ranging from 1.14 times to 8 times their recommended doses with an average of 4 times their recommended doses. Overall, three patients had seizures, three patients had renal function impairment, four patients had paresthesias either in limbs or periorally, and five patients had documented electrolyte disturbances primarily involving calcium and phosphate.

Overdose (up to 20 times the recommended dose) has been reported in post-marketing use of FOSCAVIR. Some of these post-marketing reports were relative overdoses in that the dose of FOSCAVIR had not been adjusted in patients with a reduced renal function. The pattern of adverse events associated with a FOSCAVIR overdose is consistent with the known adverse event profile of the drug.

There is no specific antidote for FOSCAVIR overdose. Hemodialysis and hydration may be of benefit in reducing drug plasma levels in patients who receive an overdosage of FOSCAVIR, but the effectiveness of these interventions has not been evaluated. The patient should be observed for signs and symptoms of renal impairment and electrolyte imbalance. Medical treatment should be instituted if clinically warranted.

CMV Retinitis

Patients should be advised that FOSCAVIR is not a cure for CMV retinitis, and that they may continue to experience progression of retinitis during or following treatment. They should be advised to have regular ophthalmologic examinations.

Mucocutaneous Acyclovir-Resistant HSV Infections

Patients should be advised that FOSCAVIR is not a cure for HSV infections. While complete healing is possible, relapse occurs in most patients. Because relapse may be due to acyclovir-sensitive HSV, sensitivity testing of the viral isolate is advised. In addition, repeated treatment with FOSCAVIR has led to the development of resistance associated with poorer response. In the case of poor therapeutic response, sensitivity testing of the viral isolate also is advised.

Effects On Ability To Drive and Use Machines

Adverse effects such as dizziness and convulsions may occur during FOSCAVIR therapy. Patients who experience seizures, dizziness, somnolence or other adverse reactions that could result in impairment, should be advised to avoid driving or operating machinery.

General

Patients should be informed that the major toxicities of foscarnet are renal impairment, electrolyte disturbances, and seizures, and that dose modifications and possibly discontinuation may be required. The importance of close monitoring while on therapy must be emphasized. Patients should be advised of the importance of reporting to their physicians symptoms of perioral tingling, numbness in the extremities or paresthesias during or after infusion as possible symptoms of electrolyte abnormalities. Patients should also be advised to promptly report any cardiac symptoms. Should such symptoms occur, the infusion of FOSCAVIR should be stopped, appropriate laboratory samples for assessment of electrolyte concentrations obtained, and a physician consulted before resuming treatment. The rate of infusion must be no more than 1 mg/kg/minute. The potential for renal impairment may be minimized by accompanying FOSCAVIR administration with hydration adequate to establish and maintain a diuresis during dosing.

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.

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.

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.