Foscarnet is an antiviral medication used to treat infection with cytomegalovirus (CMV). The drug is also used to prevent
a relapse of CMV after the initial treatment of an infection. Occassionally foscarnet also has been used to a limited
extent to treat severe herpes simplex viral infections in patients who have not responded to, or who have developed severe side effects to the antiviral agent acyclovir.
HOW should this drug be taken ?
Foscarnet is given intravenously (I.V.) as a slow infusion over 1-2 hours. The dose may be given once to three times daily
depending on the individual patient and whether the drug is used for treatment or prevention of a CMV infection. Foscarnet may be given for 2-4 weeks or indefinitely.
Foscarnet is supplied in either glass bottles or I.V. bags in a concentration of either 24 mg/ml (usually) or 12 mg/ml. The
concentration administered depends on the I.V. site. The 24 mg/ml concentration is generally used if there is a central
venous catheter in place; the 12 mg/ml diluted solution is usually used if the I.V. site is located in a smaller peripheral vein (eg. forearm).
Usually, your physician will order an infusion of normal saline before you infuse each dose of foscarnet,. Your normal
saline infusion is over 1-2 hours so your total infusion time (of the normal saline and Foscarnet) is 2-4 hours.
What should you do if you FORGET a dose?
Administer the missed dose as soon as you remember except if you remember the missed dose close to the time of the
next dose. Do not double the dose, just carry on with your regular dosing schedule. Always check to ensure that the drug has not expired before using it, especially if you have missed a dose.
What ADVERSE EFFECTS can this drug cause ? 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 and to infuse your IV normal saline as prehydration to keep
your kidneys working. Worsening of kidney function may require reducing your foscarnet dose.
The most common side effect occurring during Foscarnet therapy is nausea, which usually lasts for only the first few days of therapy. If it persists, and is bothersome, contact the clinic.
Tremor and muscle twitching, and anemia (reduced number of red blood cells that can make you tired or short of breath)
are also common problems which disappear once the drug is stopped. Contact the clinic if these symptoms develop.
Penile ulcers, though not common, may occur. Adequate hydration, good hygiene and use of a barrier cream may prevent or minimize this problem.
Foscarnet may cause other changes in your bloodwork, the most important being a fall in calcium. Call the clinic if you
notice the following symptoms of low calcium: tingling around the mouth, numbness in the hands or feet or a general
burning, tingling, or prickling feeling. Your bloodwork will be monitored and you will be notified if it is necessary to take a calcium supplement.
Irritation (redness) or pain may develop at the injection site (eg. forearm) when the Foscarnet is given into a peripheral
vein. This problem is prevented by diluting the drug (to 12 mg/ml), slowing the rate of infusion and changing the I.V. site
more frequently. This problem is also avoided by infusing the drug into a central vein.
IF YOU ARE EXPERIENCING ANY ADVERSE EFFECTS, PLEASE DISCUSS THEM WITH YOUR HEALTH CARE TEAM.
What other PRECAUTIONS should you follow while using this drug ?
Tell your physician or pharmacist about any other drugs you are taking with Foscarnet. Doses of Foscarnet or other
medications may need to be modified. Regular examination by your physician and ophthamologist are important.
How should this medication be STORED?
Foscarnet should be stored at room temperature (15-30°C). It is usable for up to 30 days if stored in either place. Once a bottle is opened it is to be used within 48 hours at home.
IF YOU HAVE ANY QUESTIONS OR CONCERNS ABOUT THIS MEDICATION, PLEASE DISCUSS THEM WITH YOUR PHARMACIST, PHYSICIAN OR NURSE.
WRITE QUESTIONS OR CONCERNS DOWN TO ENSURE THEY ARE ADDRESSED.
A pharmacist at ___________________ is available to answer questions.
The telephone number is ___________. Please ask for ____________________
