Foscarnet (Systemic)

Brand Names : Foscavir, phosphonoformic acid, PFA

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 foscarnet, the following should be considered:

Allergies - Tell your doctor if you have ever had any unusual or allergic reaction to foscarnet. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy - Foscarnet has not been studied in pregnant women. However, studies in animals have shown that foscarnet causes birth defects. Before taking this medicine, make sure your doctor knows if you are pregnant or if you may become pregnant.

Breast-feeding - It is not known whether foscarnet passes into the breast milk. Although most medicines pass into breast milk in small amounts, many of them may be used safely while breast-feeding. Mothers who are taking this medicine and who wish to breast-feed should discuss this with their doctor.

Children - 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.

Older adults - 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.

Other medicines - Although certain medicines should not be used together at all, in other cases 2 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 foscarnet, it is especially important that your health care professional know if you are taking any of the following:

• Carmustine (e.g., BiCNU) or
• Cisplatin (e.g., Platinol) or
• Combination pain medicine containing acetaminophen and aspirin (e.g., Excedrin) or other salicylates (with large amounts taken regularly) or
• Cyclosporine (e.g., Sandimmune) or
• Deferoxamine (e.g., Desferal) (with long-term use) or
• Gold salts (medicine for arthritis) or
• Inflammation or pain medicine, except narcotics, or
• Lithium (e.g., Lithane) or
• Methotrexate (e.g., Mexate) or
• Other anti-infectives (e.g., amphotericin B) or
• Penicillamine (e.g., Cupramine) or
• Plicamycin (e.g., Mithracin) or
• Streptozocin (e.g., Zanosar) or
• Tiopronin (e.g., Thiola) - Use of these medicines may increase the chance of side effects affecting the kidneys

• Pentamidine (e.g., Pentam) - Use of pentamidine injection with foscarnet may lower the level of important minerals (calcium and magnesium) in the blood; it may also increase the chance of side effects affecting the kidneys

Other medical problems - The presence of other medical problems may affect the use of foscarnet. Make sure you tell your doctor if you have any other medical problems, especially:

• Anemia - Foscarnet may cause or worsen anemia

• Dehydration or
• Kidney disease - Patients who are dehydrated or have kidney disease may have an increased chance of side effects