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Pyrimethamine (Systemic)

Contents of this page:

Brand Names

Some commonly used brand names are:

In the U.S.--

In Canada--


Category


Description

Pyrimethamine (peer-i-METH-a-meen) is an antiprotozoal ((AN-tee-proe-toe-ZOE-al)) medicine. Antiprotozoals work by killing protozoa (tiny, one-celled animals) or preventing their growth. Some protozoa are parasites that can cause many different kinds of infections in the body.

This medicine is used with one or more other medicines to treat malaria and toxoplasmosis ((tok-soe-plaz-MOE-sis)) . This medicine may also be used for other problems as determined by your doctor.

Pyrimethamine is available only with your doctor's prescription, in the following dosage form:


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--Studies in humans have not shown that pyrimethamine causes birth defects. Also, use in pregnant women has not shown pyrimethamine to cause birth defects. However, use is not generally recommended during the first 3 to 4 months of pregnancy. Studies in animals have shown that pyrimethamine may cause birth defects, anemia, or other problems, especially when given in large doses.

Breast-feeding--Pyrimethamine passes into breast milk. However, problems in nursing babies have not been reported.

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:

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:


Proper Use of This Medicine

Keep this medicine out of the reach of children . Overdose is especially dangerous in children.

If this medicine upsets your stomach or causes vomiting, it may be taken with meals or a snack.

If you are taking this medicine to treat malaria , take the number of tablets your doctor told you to take (up to 3) once, as a single dose, along with other medicine your doctor gave you. If you develop a fever and are not near a medical facility, and are taking this medicine to treat what you think may possibly be malaria, take the number of tablets your doctor told you to take (up to 3) once, as a single dose.

This medicine works best when you take it on a regular schedule. If you are to take two doses a day, one dose may be taken with breakfast and the other one with the evening meal. Make sure that you do not miss any doses . If you have any questions about this, check with your health care professional.

Dosing--The dose of pyrimethamine 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 pyrimethamine. If your dose is different, do not change it unless your doctor tells you to do so.

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 taking pyrimethamine .

Missed dose--If you do miss a dose of this medicine, take it as soon as possible. This will help you to keep taking your medicine on a regular schedule. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage--To store this medicine:


Precautions While Using This Medicine

It is very important that your doctor check you at regular visits for any blood problems that may be caused by this medicine, especially if you will be taking this medicine in high doses for toxoplasmosis.

If your symptoms do not improve within a few days or if they become worse, check with your doctor.

If this medicine causes anemia, your doctor may want you to take leucovorin (e.g., folinic acid, Wellcovorin) to help clear up the anemia. If so, it is important to take the leucovorin every day while you are taking this medicine. Do not miss any doses.

Pyrimethamine, especially in high doses, may cause blood problems. These problems may result in a greater chance of certain infections, slow healing, and bleeding of the gums. Therefore, you should be careful when using regular toothbrushes, dental floss, and toothpicks. Dental work should be delayed until your blood counts have returned to normal. Check with your medical doctor or dentist if you have any questions about proper oral hygiene (mouth care) during treatment.


Side Effects of This Medicine

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:

Other 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. However, check with your doctor if any of the following side effects continue or are bothersome:

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.


Additional Information

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, pyrimethamine is used in certain patients with the following medical conditions:

For patients taking this medicine for Pneumocystis carinii pneumonia:

Other than the above information, there is no additional information relating to proper use, precautions, or side effects for these uses.


Revised: 05/18/99
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