Pyrimethamine is an antiprotozoal that belongs to a class of medications called diaminopyrimidine. It inhibits dihydrofolate reductase and works against Plasmodia and Toxoplasma.
It is indicated for the treatment and management of malaria as well as treatment of toxoplasmosis. Pyrimethamine is also used to treat isosporiasis and Pneumocystis carinii pneumonia.
Pyrimethamine is used concomitantly with other medications in the treatment of Pneumocystis carinii pneumonia.
You can only buy this medication with a prescription, and it is sold as a tablet.
2 What to Know Before Using
You and your physician must discuss the pros and cons of using pyrimethamine before beginning the treatment. There are several factors you need to consider to make sure that this medication will suit you.
You should not take pyrimethamine if you have had allergic reactions to it or any of its ingredients. See the information sheet for a full list of ingredients.
You should also tell your doctor if you have allergies to animals, dyes, preservatives, foods, and other medicines. Effective doses of pyrimethamine in pediatric patients have the same effects as in adult patients.
However, there hasn’t been enough research regarding its effects on the elderly. Pyrimethamine should only be given to pregnant women if the benefits outweigh the risks.
Concomitant folinic acid use is strongly recommended in such cases. This medicine poses minimal risk to the breastfeeding infant. Pyrimethamine should never be used concomitantly with aurothioglucose.
On the other hand, concomitant use of methotrexate, sulfamethoxazole, trimethoprim, and zidovudine is usually not recommended but can be necessary.
Using lorazepam simultaneously with pyrimethamine can increase the risk of side effects.
Tell your doctor if you have any of the following conditions:
Pyrimethamine may be taken with food if it upsets your stomach. If you are using pyrimethamine to treat malaria, take the prescribed number of tablets at the prescribed time.
For those taking two doses, one should be taken in the morning and the other one in the evening. Pyrimethamine is most effective when taken regularly so see to it that you take it at the same time of the day.
The dose and timing of this medicine will depend on the condition being treated, so you need to follow your doctor’s instructions carefully.
For malaria treatment, adult and adolescent patients should take 25 mg of pyrimethamine daily with a sulfonamide for 2 days while children should get the prescribed dose based on their body weight.
For toxoplasmosis treatment, adult and adolescent patients should take 50 to 75 mg daily together with other medications for several weeks. Your dose will be decreased by your physician after the first week.
For children, the dose will depend on their body weight. For malaria prevention, adults and the adolescent patient should take 25 mg once a week.
For children, the dose should be determined by the physician. Take missed doses as soon as remembered but skip it if it’s almost time for the next one.
Keep pyrimethamine tablets in a sealed container away from children’s reach. Overdose in children can be fatal.
4 Precautions to Take
Go to your follow-up appointments regularly. Try not to miss any because your doctor needs to check your progress and prevent any side effects.
Regular laboratory exams may also be needed since pyrimethamine can cause several blood problems.
If you develop anemia, your physician may prescribe leucovorin which is to be taken daily while you are on pyrimethamine.
Having blood problems can mean slow healing, easy bleeding or bruising, and increased susceptibility to infections.
So while taking pyrimethamine, practice gently oral hygiene, and do not engage in contact sports, and be careful around sharp edges.
You may delay any type of dental work until your blood exam results normalize. Lastly, you should also consult your physician if your condition doesn’t get any better in a few days.
5 Potential Side Effects
There are also several side effects associated with pyrimethamine.
The usual side effects of this medicine include loss of appetite, nausea, vomiting, headache, insomnia, lightheadedness, or dry mouth.
Other major side effects include black/tarry stools, coughing, fever/chills, blood in urine or stools, tongue irritation, lower back or side pain, pinpoint red spots on the skin, unusual bleeding/bruising and difficult urination.
If you experience any of those, consult your doctor right away. You may also develop diarrhea, nausea, and vomiting.
If you experience a symptom that is not mentioned here, get in contact with your doctor right away.
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