Pyrimethamine is an antiparasitic drug used to treat toxoplasmosis, a disease caused by infection with the parasite Toxoplasma gondii.  Pyrimethamine can be used to treat toxoplasmosis in pregnant women.

Pyrimethamine works by inhibiting the use of folic acid by the parasite. In the life cycle of the parasite, folic acid is required for protein production. That way, the development and growth of new parasites can be prevented.

Apart from toxoplasmosis, pyrimethamine can also be used to prevent and treat malaria caused by infection with the plasmodium parasite. However, to be effective, pyrimethamine needs to be combined with certain antimalarial drugs.

Pyrimethamine trademark: Primet

What is Pyrimethamine

class Prescription drug
Category Antiparasitic
Benefit Treating toxoplasmosis or preventing and treating malaria
Consumed by Adults and children
Pyrimethamine for pregnant and lactating women Category C: Studies in animals have shown an adverse effect on the fetus, but there have been no controlled studies in pregnant women.

Drugs should only be used if the expected benefit outweighs the risk to the fetus.

Pyrimethamine can be absorbed into breast milk. If you are breastfeeding, do not use this medication without consulting your doctor first.

Drug form Tablet

Precautions Before Taking Pyrimethamine

Pyrimethamine should only be used with a doctor's prescription. Before starting to consume it, pay attention to the following things:

  • Do not take pyrimethamine if you are allergic to this drug.
  • Tell your doctor if you have ever had or are suffering from G6PD deficiency , seizures or epilepsy , kidney problems, liver problems, megaloblastic anemia , low red blood cell, white blood, or platelet counts, low folate levels, impaired absorption of food, malnutrition , or alcohol addiction .
  • Tell your doctor if you are using other drugs, supplements or herbal products, to anticipate drug interactions.
  • Tell your doctor if you are pregnant, breastfeeding or planning a pregnancy.
  • Tell your doctor if you are taking pyrimethamine before having any laboratory tests or medical procedures, including surgery.
  • Immediately see a doctor if you experience a drug allergic reaction or serious side effects, after taking pyrimethamine.

Dosage and Rules for Using Pyrimethamine

The dose of pyrimethamine depends on the patient's age and weight. Here are common pyrimethamine dosages based on treatment goals:

Purpose : Treat toxoplasmosis

  • Adult: 50–75 mg daily, for 1–3 weeks. Follow-up dose of 25–37.5 mg daily, for 4–5 weeks.
  • Children aged 5–6 years : Initial dose of 2 mg/kg per day divided into 2 consumption schedules, for 3 days. Maintenance dose 1 mg/kg per day, for 4 weeks. The maximum dose is 50 mg per day.

Purpose : Treating toxoplasmosis in pregnant women

  • Adult: 25–50 mg in combination with sulfadiazine and leucovorin.

Purpose : Treating toxoplasmosis from birth (congenital toxoplasmosis)

  • Children aged> 2 months: Initial dose of 2 mg/kg per day divided into 2 consumption schedules, for 2 days. Maintenance dose 1 mg/kg per day for 2–6 months. The next dose is 1 mg/kg per day, 3 times per week, until the child is 1 year old

Pyrimethamine can be used to treat malaria due to uncomplicated Plasmodium falciparum , and to prevent malaria in residents in malaria endemic areas.

In use, pyrimethamine must be combined with sulfadoxine. In addition, therapy can also be supplemented with several other antimalarial drugs, such as amodiaquine or artesunate.

How to Take Pyrimethamine Properly

Follow the doctor 's recommendations and read the information listed on the pyrimethamine packaging before starting to consume it.

Pyrimethamine should be taken with food or immediately after food. Consumption of pyrimethamine regularly so that this drug can work effectively.

Try to take pyrimethamine at the same time every day. If the drug is taken weekly, take this medication on the same day each week.

If you forget to take pyrimethamine, consume it as soon as you remember if the break with the next consumption schedule is not too close. If it is close, ignore the dose and do not double the next dose.

Keep taking pyrimethamine according to your doctor's prescription even if you feel better. Stop taking this drug before the specified time can cause the parasite to become resistant to the drug or cause serious side effects.

While taking pyrimethamine, you may need to have regular blood tests to check your body's response to this drug. In addition, follow the control schedule that has been planned by the doctor.

Store pyrimethamine in a dry place away from direct sunlight, and keep this drug out of reach of children.

Pyrimethamine Interactions with Other Drugs

Pyrimethamine can cause interaction effects when used with certain drugs. Here are some interactions between drugs that can occur:

  • Decreased absorption and effectiveness of pyrimethamine when used with antacids or kaolin
  • Decreased blood levels of folic acid when used with co- trimoxazole , zidovudine or methotrexate
  • Increased risk of liver damage when used with lorazepam
  • Increased risk of seizures in people with leukemia when used with methotrexate
  • Increased risk of aplastic anemia when used together with daunorubicin in patients with acute myeloblastic leukemia

Pyrimethamine Side Effects and Dangers

Some of the side effects that may arise after consuming pyrimethamine are:

  • Diarrhea
  • Stomach ache or heartburn
  • Nausea or vomiting
  • Lost appetite

Consult your doctor if the side effects above do not improve immediately or get worse. You need to see a doctor immediately if you experience an allergic drug reaction or serious side effects, such as:

  • Urine is pink or bloody
  • Chest pain or a beating heart that is fast, slow, or irregular
  • Unusual bruising or bleeding
  • Serious infection , which can be characterized by high fever , chills, severe tiredness, or sore throat that doesn't get better
  • Anemia , which can be characterized by extreme fatigue; pale skin, lips, or nails; heart palpitations or breathing faster than usual during light activity
  • Swollen or sore tongue
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