Pyrimethamine (Systemic)

Brand Names : Daraprim

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 pyrimethamine, the following should be considered:

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

Pregnancy - Pyrimethamine has not been studied in pregnant women. However, studies in animals have shown that pyrimethamine causes birth defects such as cleft palate, brachygnathia (abnormal shortness of the jaw bone), oligodactyly (fewer than 5 digits on a hand or foot), microphthalmia (abnormal smallness of the eye). Before taking this medicine, make sure your doctor knows if you are pregnant or if you may become pregnant.

Breast-feeding - Pyrimethamine passes into breast milk. However, problems in nursing babies have not been reported. Mothers who are taking this medicine and who wish to breast-feed should discuss this with their doctor.

Children - Pyrimethamine has been used in children and, in effective doses, has not been shown to cause different side effects or problems in children than it does in adults.

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 pyrimethamine in the elderly with use in other age groups.

Other medicines - 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 pyrimethamine, it is especially important that your health care professional know if you are taking any of the following:

• Amphotericin B by injection (e.g., Fungizone) or
• Antineoplastics (cancer medicine) or
• Antithyroid agents (medicine for overactive thyroid) or
• Azathioprine (e.g., Imuran) or
• Chloramphenicol (e.g., Chloromycetin) or
• Colchicine or
• Cyclophosphamide (e.g., Cytoxan) or
• Flucytosine (e.g., Ancobon) or
• Ganciclovir (e.g., Cytovene) or
• Interferon (e.g., Intron A, Roferon-A) or
• Mercaptopurine (e.g., Purinethol) or
• Methotrexate (e.g., Mexate) or
• Plicamycin (e.g., Mithracin) or
• Zidovudine (e.g., AZT, Retrovir) - Use of these medicines together with pyrimethamine may increase the chance of side effects affecting the blood

• Bone marrow suppressants (methotrexate [e.g., Rheumatrex], proguanil [e.g., Malarone], sulfonamides [medicines used to treat infections], trimethoprim-sulfamethoxazole [e.g., Bactrim], zidovudine [e.g., Retrovir]) - may increase risk of bone marrow problems

• Lorazepam (e.g., Ativan) - Mild liver problems have been reported when using this medicine together with pyrimethamine

• Phenytoin (e.g., Dilantin) - Use of this medicine together with pyrimethamine may affect folate (vitamin B) levels in the body

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

• Allergy to pyrimethamine or any ingredient in the medicine - pyrimethamine should not be used

• Anemia or other blood problems - High doses of pyrimethamine may make these conditions worse

• Kidney problems or
• Liver problems or
• Lack of vitamin B in the body caused by
  • Alcoholism (drinking too much alcohol) or
  • Malabsorption syndrome (when a person's body does not absorb enough nutrients from the food they eat)
  - May make the condition worse

• Seizure disorders, such as epilepsy - High doses of pyrimethamine may increase the chance of convulsions (seizures)