Pyrimethamine: functions, dosage, side effects, how to use

What drug pyrimethamine?

What is pyrimethamine for?

Pyrimethamine is a drug that is used with other drugs (such as sulfonamides) to treat a serious parasitic infection (toxoplasmosis) of the body, brain, or eyes, or to prevent toxoplasmosis infection in people infected with HIV. Very rarely but probably, pyrimethamine is used with sulfadoxine to treat malaria. The CDC no longer recommends using pyrimethamine alone to prevent or treat malaria. Pyrimethamine belongs to a class of drugs known as antiparasitic. It works by killing parasites.

OTHER USES: This section contains uses of this drug that are not listed on the approved professional label for the drug, but which may be prescribed by your healthcare professional. Use this medication for the conditions listed in this section only if it has been so prescribed by your healthcare professional.

This drug can also be used with other drugs (such as dapsone) for the prevention and treatment of pneumonia in AIDS patients.

How is pyrimethamine used?

Take this medication by mouth, usually once or twice daily or as directed by your doctor. This medicine is taken with food to reduce nausea and vomiting. If vomiting is severe or persists, your doctor may lower the dose or instruct you to stop taking this medicine. The doctor will prescribe another drug (folinic folic acid) to prevent blood problems caused by pyrimethamine. Follow your doctor's instructions carefully. Drink plenty of fluids to prevent kidney problems if you are taking the drug "sulfa" with pyrimethamine.

This drug works best when the amount of medicine in your body is kept at a constant level. Therefore, take this drug and other anti-parasitic drugs regularly, exactly as prescribed by your doctor. To help you remember, consume it at the same time each day.

Dosage is based on the type of infection, your health condition, age, and response to treatment. The length of time you take this medication will depend on your infection. Your dose must be carefully adjusted by your doctor to treat infections and prevent serious side effects. Follow your doctor's instructions carefully.

Do not take this drug more or less than prescribed. Do not stop taking this medication before completing this prescription even if you feel better, unless directed to do so by your doctor. Skipping or changing doses without a doctor's approval can cause the parasite count to increase, make the infection more difficult to treat (resistant to), or worsen side effects.

Tell your doctor if your condition persists or gets worse.

How is pyrimethamine stored?

This medication is best stored at room temperature, away from direct light and damp places. Don't keep it in the bathroom. Don't freeze it. Other brands of this drug may have different storage rules. Observe the storage instructions on the product package or ask your pharmacist. Keep all medicines away from children and pets.

Do not flush medicines down the toilet or down the drain unless instructed to do so. Discard this product when it has expired or when it is no longer needed. Consult your pharmacist or local waste disposal company about how to safely dispose of your product.

Pyrimethamine Dosage

The information provided is not a substitute for medical advice. ALWAYS consult your doctor or pharmacist before starting treatment.

What is the dose of pyrimethamine for adults?

Usual Adult Dose for Malaria Prophylaxis
25 mg orally once a week. Prophylaxis should be started one week before departure and continued for at least 6 to 10 weeks after exposure.

Usual Adult Dose for Toxoplasmosis
Initially: sulfonamide 50 to 75 mg orally once a day with 1 to 4 g (eg, sulfadoxine, sulfadiazine). Continue for 1 to 3 weeks, depending on response and dose tolerance. The dose for each drug can then be reduced by one-half and continued for 4 or 5 weeks. Patients receiving pyrimethamine should also receive folinic acid.

Usual Adult Dose for Toxoplasmosis - Prophylaxis
1 mg / kg or 15 mg / m2 (max 25 mg) orally every day plus folinic acid (leucovorin) 5 mg orally every 3 days plus sulfadiazine 85-120 mg / kg / day divided into 2 to 4 oral doses. Clindamycin 20 to 30 mg / kg / day can be used in place of sulfadiazine as an alternative regimen.

Usual Adult Dose for Prophylactic Pneumonia Pneumonia
50 to 75 mg orally once a week. Pyrimethamine is used in combination with dapsone and leucovorin. It is considered an alternative regimen for patients who cannot tolerate trimethoprim-sulfamethoxazole.

What is the dose of pyrimethamine for children?

Usual Pediatric Dose for Malaria Prophylaxis
Less than 4 years: 6.25 mg orally once a week.
4 to 10 years: 12.5 mg orally once a week.

Usual Pediatric Dose for Toxoplasmosis

Newborns and toddlers:
Initial: 2 mg / kg / day orally divided every 12 hours for 2 days, then 1 mg / kg / day once daily given with sulfadiazine for the first 6 months; 6 months later: 1 mg / kg / day 3 times per week with sulfadiazine; Oral folinic acid should be given 5 to 10 mg 3 times per week to prevent haematological toxicity.

1 to 12 years: 2 mg / kg / day divided every 12 hours for 3 days followed by 1 mg / kg / day (maximum 25 mg / day) once daily or divided twice daily for 4 weeks given with sulfadiazine; Oral folinic acid should be given 5 to 10 mg 3 times per week to prevent haematological toxicity.

In what dosage is pyrimethamine available?

25 mg tablet

Pyrimethamine side effects

What side effects can be experienced due to pyrimethamine?

Stop taking pyrimethamine and seek medical help immediately if you experience an allergic reaction (swelling of the lips, tongue, or face, difficulty breathing, closure of the throat, or hives) during treatment with pyrimethamine.

Stop using pyrimethamine and seek medical help immediately when the first signs of skin rash, sore throat, skin rash, unusual bruising under the skin, or swelling of the tongue appear. This may be an early symptom of a serious side effect of pyrimethamine.

Other milder side effects may occur. Continue taking pyrimethamine and talk to your doctor if you experience:

- nausea, vomiting, or loss of appetite
- insomnia
- headache
- light
- dryness of the mouth

Not everyone experiences the following side effects. There may be some side effects not mentioned above. If you have concerns about certain side effects, consult your doctor or pharmacist.

Pyrimethamine Drug Warnings and Cautions

What should be known before using pyrimethamine?

Before using a particular medication, consider the risks and benefits first, which is a decision you and your doctor should make. For this drug, pay attention to the following:

Allergy

Tell your doctor if you have any unusual or allergic reactions to this or any other medicine. Also tell your doctor if you have any other types of allergies such as to food, coloring, preservatives, or animal allergies. For over-the-counter products, read the labels on the packaging 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 in adults.

Elderly

Many drugs have not been studied specifically in older people. Therefore, it may not be known whether this drug works in the same way as in younger adults or if it causes different side effects or problems in the elderly. There is no specific information comparing pyrimethamine use in the elderly with that used in other age groups.

Is pyrimethamine safe for pregnant and breastfeeding women?

There is no adequate research on the risks of using this drug in pregnant or breastfeeding women. Always consult your doctor to weigh the potential benefits and risks before using this medication. This drug is included in the risk of pregnancy category C according to the US Food and Drug Administration (FDA).

The following references the pregnancy risk categories according to the FDA:

• A = No risk,
• B = not at risk in several studies,
• C = May be risky,
• D = There is positive evidence of risk,
• X = Contraindicated,
• N = Unknown

Research in women has shown that this drug poses minimal risk to the baby when used during breastfeeding.

Pyrimethamine Interactions

What drugs may interact with pyrimethamine?

Taking this drug with any of the following medicines is not recommended. Your doctor may not prescribe this medicine to you or will replace some of the drugs you are already taking.

• Aurothioglucose

Using this medication with any of the following medicines is not usually recommended, but may be necessary in some cases. If the two drugs are prescribed together, your doctor may change the dose or how often you use one or both drugs.

• Sulfamethoxazole
• Methotrexate
• Trimethoprim
• Zidovudine

Taking this medication with the drugs below may increase your risk of side effects, but in some cases, a combination of these two drugs may be the best treatment. If both drugs are prescribed for you, your doctor will usually change the dosage or determine how often you should take them.

• Lorazepam

Can food or alcohol interact with pyrimethamine?

Certain drugs should not be used while eating or eating certain foods because drug interactions can occur. Consuming alcohol or tobacco with certain drugs can also cause interactions to occur. Discuss your use of drugs with food, alcohol, or tobacco with your health care provider.

What health conditions can interact with pyrimethamine?

Any other health conditions you have can affect the use of this drug. Always tell your doctor if you have other health problems, especially:

• allergies to pyrimethamine or any ingredient in the drug - pyrimethamine should not be used
• anemia or other blood problems - high doses of pyrimethamine might make the condition worse
• kidney problems
• heart problem
• deficiency of B vitamins in the body caused by alcoholism (drinking too much alcohol) or malabsorption syndrome (when a person's body doesn't absorb enough nutrients from the food they eat)
• maintenance of seizures, such as epilepsy - high doses of pyrimethamine can increase the chance of having a seizure

Pyrimethamine overdose

What should I do in an emergency or overdose?

In case of an emergency or overdose, contact the local emergency services provider (112) or immediately to the nearest hospital emergency department.

Symptoms of overdose may include: abdominal pain, severe / recurrent vomiting, vomiting of blood, seizures, slow / shortness of breath, inability to wake up.

What should I do if I miss a dose?

If you forget a dose of this medicine, take it as soon as possible. However, when it is nearing the time of the next dose, skip the missed dose and return to the usual dosing schedule. Don't double the dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.