How does it work?
Pyrimethamine belongs to a group of medications called the antimalarials. It is used in combination with other antimalarials in either the treatment or prevention of malaria.
Malaria is caused by an organism which is classed as a protozoa and is a parasite which is carried by mosquitoes. During a bite from a mosquito, the parasite passes into the body. Once inside, it lives and reproduces. This results in the infection known as malaria.
In the blood, malaria parasites break down a part of the red blood cells known as haemoglobin. When this happens haemoglobin is divided into two parts; haem and globin.
Haem is toxic to the malaria parasite. To prevent it from being damaged, the malaria parasite produces an chemical which converts the toxic haem into a non-toxic compound.
Pyrimethamine works by blocking the production of a chemical called folinic acid inside the parasite. Folinic acid is essential in the production of new genetic material (DNA). DNA is necessary for the parasite to reproduce, therefore by blocking it's formation this prevents the malarial parasites from increasing in number.
Pyrimethamine is not used on its own, but is combined with sulfadoxine (Fansidar) for the treatment or dapsone (Maloprim) for the prevention of malaria.
What is it used for?
Malaria
Toxoplasmosis
Warning!
People taking this medicine should have regular blood tests.
Adequate folate supplementation should be given to women who are pregnant.
Use with caution in
Kidney disease
Liver disease
Pregnancy and Breastfeeding
Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.
This medicine should be used with caution during pregnancy, and only if the expected benefit to the mother is greater than the possible risk to the foetus, particularly in the first trimester. Seek medical advice from your doctor.
This medicine should be used with caution by breastfeeding mothers, and only if the expected benefit to the mother is greater than any possible risk to the baby. Seek medical advice from your doctor.
Side effects
Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.
Difficulty in sleeping (insomnia)
Anaemia where the cells in the bone marrow that are to form red blood cells are larger than normal, usually due to a deficiency in folic acid or vitamin B12 (megaloblastic anaemia)
Rash
The side effects listed above may not include all of the side effects reported by the drug's manufacturer.
For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.
How can this medicine affect other medicines?
Pyrimethamine may decrease the body's folate levels if it is taken with the following medications:
-Methotrexate
-Phenytoin
-Co-trimoxazole
-Trimethoprim
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