Pronunciation:

peer-i-METH-a-meen

Brand Names:

• Daraprim

Dosage Forms:

• Tablet

Classifications:

Therapeutic—

Antimalarial

Pharmacologic—

Folic Acid Antagonist

Uses of This Medicine:

Pyrimethamine is an antiprotozoal 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 and prevent malaria and to treat toxoplasmosis. This medicine may also be used for other problems as determined by your doctor.

Pyrimethamine is available only with your doctor's prescription.

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:

• Isosporiasis (treatment and prevention)
• Pneumocystis carinii pneumonia (treatment)

For patients taking this medicine for Pneumocystis carinii pneumonia:

• Pyrimethamine is used in combination with other medicines for mild to moderate pneumonia in patients who cannot take standard treatment.

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:

Allergies—

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.

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.

Pregnancy—

	Pregnancy Category	Explanation
All Trimesters	C	Animal studies have shown an adverse effect and there are no adequate studies in pregnant women OR no animal studies have been conducted and there are no adequate studies in pregnant women.

Breast-feeding—

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.

Other medicines—

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.

• Aurothioglucose

Other interactions—

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:

• 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)

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 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.

• For the treatment of malaria:
  • Adults and adolescents: 25 milligrams of pyrimethamine daily together with a sulfonamide for 2 days. These two medicines may also be taken with other medicine. This will be determined by your doctor.
  • Children: Dose is based on body weight and will be determined by the doctor. Pyrimethamine may be taken together with other medicines.
• For the treatment of toxoplasmosis:
  • Adults and adolescents: Starting dose if 50 to 75 milligrams of pyrimethamine daily taken together with other medicines for several weeks. After one to three weeks, your doctor may lower your dose. The proper dose for you must be determined by the doctor.
  • Children: Dose is based on body weight and must be determined by the doctor.
• For the prevention of malaria:
  • Adults and adolescents: 25 milligrams taken once a week.
  • Children: Dose is based on age and must be determined by the doctor.

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. 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—

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

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:

Less common

Black, tarry stools

blood in urine or stools

cough or hoarseness

fever or chills

irritation or soreness of tongue

lower back or side pain

painful or difficult urination

pinpoint red spots on skin

unusual bleeding or bruising

Rare

Bleeding or crusting sores on lips

chest pain or discomfort

muscle cramps or pain

redness, blistering, peeling, or loosening of skin

skin rash

sores, ulcers, and/or white spots in mouth

sore throat

unusual tiredness or weakness

Frequency not known

Blood in urine

diarrhea

difficulty swallowing

dizziness

fainting spells

fast, slow, or irregular heartbeat

hives

itching

joint or muscle pain

lightheadedness

pale skin

pounding or rapid pulse

puffiness or swelling of the eyelids or around the eyes, face, lips or tongue

rapid breathing

red, irritated eyes

red skin lesions, often with a purple center

shortness of breath

swollen glands

tightness in chest

unexplained bleeding or bruising

wheezing

Symptoms of overdose

Abdominal or stomach pain

convulsions (seizures)

increased excitability

vomiting (severe and continuing)

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:

Less common

Diarrhea

loss of appetite

nausea

vomiting

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