Foscarnet (Intravenous route)
Renal impairment is the major toxicity of foscarnet sodium. Frequent monitoring of serum creatinine, with dose adjustment for changes in renal function, and adequate hydration with administration of foscarnet sodium, is imperative. Seizures, related to alterations in plasma minerals and electrolytes, have been reported. Mineral and electrolyte supplementation may be required .
Viral DNA Polymerase Inhibitor
Uses of This Medicine:
Foscarnet is used to treat the symptoms of cytomegalovirus (CMV) infection of the eyes in patients with acquired immune deficiency syndrome (AIDS). Foscarnet will not cure this eye infection, but it may help to control worsening of the symptoms. It is also used to treat herpes simplex virus (HSV) infections of the skin and mucous membranes in people who are immunocompromised and whose infections did not improve with other therapy. Foscarnet may also be used for other serious viral infections as determined by your doctor. However, it does not work in treating certain viruses, such as the common cold or the flu.
Foscarnet is administered only by or under the supervision of your doctor.
Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although these uses are not included in product labeling, foscarnet is used in certain patients with the following medical conditions:
Before Using This Medicine:
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
There is no specific information comparing use of foscarnet in children with use in other age groups. Foscarnet can cause serious side effects in any patient. Therefore, it is especially important that you discuss with the child's doctor the good that this medicine may do as well as the risks of using it.
Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of foscarnet in the elderly with use in other age groups.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.
Other medical problems—
The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:
Proper Use of This Medicine:
To ensure the best response, foscarnet must be given for the full time of treatment. Also, this medicine works best when there is a constant amount in the blood. To help keep the amount constant, foscarnet must be given on a regular schedule.
Several glasses of water should be taken every day, unless otherwise directed by your doctor. Drinking extra water will help to prevent some unwanted effects foscarnet has on the kidneys.
This medicine may cause sores on the genitals (sex organs). Washing your genitals after urination may decrease the chance of your developing this problem.
The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
Precautions While Using This Medicine:
It is very important that your doctor check your progress at regular visits. This will allow your doctor to check for possible unwanted effects.
It is also very important that your ophthalmologist (eye doctor) check your eyes at regular visits since you may have some loss of eyesight due to retinitis even while you are receiving foscarnet.
Side Effects of This Medicine:
Along with their needed effects, medicines like foscarnet can sometimes cause serious side effects such as kidney problems; these are described below. Foscarnet may also decrease the amount of calcium in your blood, causing you to have a tingling sensation around your mouth, and pain or numbness in your hands and feet. If this occurs, especially while you are receiving the medicine, notify your health care professional immediately.
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Last Updated: 4/4/2014
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