Foscarnet

FOSCARNET
Other Names: Foscavir® WHY is this drug prescribed? Foscarnet is an antiviral drug used to treat infections caused by cytomegalovirus (CMV) (ie: retinitis). This drug is also used to prevent a relapse of CMV after the initial treatment of this infection. You should have your eyes checked on a regular basis. Occasionally, foscarnet can be used to treat severe herpes simplex viral (HSV)infections in patients who have not responded to, or who have developed severe adverse effects to the antiviral agent acyclovir. HOW should this drug be taken? Foscarnet is given intravenously (I.V.) as a slow infusion over 1 to 2 hours. The dose may be given once to three times daily depending on your needs and depending on the reason it is prescribed (treatment versus prevention). The exact dosewill be calculated based on your weight and may need to be adjusted if you have kidney problems. Foscarnet may be given for 2 to 4 weeks or indefinitely. Your dosage is: ___mL (____mg) over ____hours ____times a day In your area, foscarnet will be supplied to you by ___________________________. Usually, your doctor will prescribe an infusion of normal saline that is to be received intravenouslybefore each dose of foscarnet. Your normal saline infusion will be given over 1 to 2 hours. Overall, it will take 2 to 4 hours to receive each dose.

What should you do if you FORGET a dose? Foscarnet will likely by given at a clinic by an experienced nurse. Ensure that you do not miss your appointment to receive your dose of foscarnet. Missing doses of foscarnet may cause your CMV infection tocome back or worsen. If you have missed an appointment, call your clinic immediately to rebook an appointment to receive your dose as soon as possible. If you are receiving foscarnet at home and you have missed a dose, administer it as soon as possible. However, if it is time for your next dose, do not double the dose, just carry on with your regular schedule. What ADVERSE EFFECTS can this drugcause? What should you do about them? The most serious problem with foscarnet is that it can have a harmful effect on the kidneys. Certain blood tests measuring kidney function (eg. creatinine) will be done regularly to check how well your kidneys are working during therapy. It is important to drink as much fluid as you can. Also, the intravenous normal saline will help protect your kidneys. Pleasenotify your doctor if you urinate less than usual. The most common adverse effects occurring during foscarnet therapy are nausea, vomiting, fatigue, headache and diarrhea. These symptoms usually last for only the first few days of therapy. If they persist and are bothersome, contact your doctor or pharmacist. Tremor, muscle twitching, convulsions and dizziness sometimes occur and disappear once thedrug is stopped. Contact your doctor if you notice these symptoms. Anemia (a reduced number of red blood cells that can make you feel tired or short of breath), leukopenia (a decrease in the number of white

blood cells so that you have a higher risk of bacterial infection), or thrombocytopenia (a decrease in the number of platelets that can increase your risk of bleeding or bruising) mayoccur. Blood tests will be done regularly to check for any changes in these values. Inform your doctor if you notice any symptoms of fever, chills, shortness of breath, rapid or irregular heartbeat, fatigue, bleeding or bruising. Penile, vaginal and mouth ulcers, though not common, may occur. Adequate hydration and good hygiene may prevent or minimize these problems. Foscarnet may cause other changesin your blood work, the most important being a fall in calcium. Your doctor will also check for increases in phosphate and for decreases in phosphate, potassium and magnesium. Call the clinic if you notice the following symptoms that are caused by low calcium levels: tingling around the mouth, numbness in the hands or feet or a general burning, tingling, or prickling feeling. Your blood work will...