The active substance Pyrimethamine is a so-called anti-parasitic drug. Pyrimethamine belongs to the category of anti-parasitic drugs and is primarily used for the prophylaxis of malaria and for the treatment of toxoplasmosis. The substance pyrimethamine is a derivative of diaminopyrimidine and is suitable in combination with other active ingredients for the prevention of pneumonia caused by Pneumocystis jirovecii.
What is pyrimethamine?
In principle, the drug pyrimethamine is one of the diaminopyrimidines and is used to treat infections caused by protozoa. The medicine is very often used for toxoplasmosis. In Germany and Switzerland, the substance pyrimethamine is part of the drug Daraprim® from the pharmaceutical manufacturer GlaxoSmithKline. Basically, the active ingredient pyrimethamine should always be taken together with sulfonamide.
The drug pyrimethamine works by inhibiting dihydrofolate reductase. This is a special enzyme that plays an important role in the availability of the vitamin folic acid.
The active ingredient pyrimethamine is characterized among other things by its anti-parasitic properties. The substance's effect is primarily due to the fact that it inhibits the metabolism for the production of folic acid. For this reason, it is imperative that the affected patient take folic acid during treatment.
Pyrimethamine is also synonymous as Pyrimethaminum or Pirimethamine designated. The substance is usually present as a crystalline powder of white color. In some cases, pyrimethamine appears as a crystal and is almost insoluble in water.
Pharmacological effect
The drug pyrimethamine is characterized by a typical mechanism of action. First of all, it has anti-parasitic properties and is an anti-protozoal agent. The drug thus acts against plasmodia, Toxoplasma gondii and Pneumocystis carinii, among others. Basically, the active ingredient pyrimethamine interacts with the folic acid metabolism. Pyrimethamine is characterized by an extremely long half-life, which is up to 85 hours.
It is believed that the active ingredient pyrimethamine intervenes in the energetic metabolism of parasites. When the drug pyrimethamine is taken orally, it affects the parasites' dihydrofolate reductase. This prevents the synthesis of folic acid.
It is often used together with sulfonamides or sulfones, which increases the effect. The active ingredient pyrimethamine is only absorbed gastrointestinally. Ultimately, the drug is excreted from the organism via the kidneys. The half-life of the substance is two to six days.
Medical application & use
The drug pyrimethamine is suitable for the drug treatment of various diseases and ailments as well as for the prevention of some infections. It is very often used for the therapy of toxoplasmosis, whereby it is usually used together with a sulfonamide. The dosage of the drug is always carried out in accordance with the accompanying technical information.
During therapy with the active ingredient pyrimethamine, it is necessary to take folic acid. This reduces the risk of bone marrow suppression. Basically, all sulphonamides should be taken with plenty of water. In addition to toxoplasmosis, the drug pyrimethamine is also suitable for the treatment of malaria and Pneumocystis jirovecii pneumonia.
Risks & side effects
During treatment with the drug pyrimethamine, some of the patients experience undesirable side effects. However, these differ depending on the individual case and also occur with varying frequencies. Most frequently, the active substance pyrimethamine causes blood count disorders and anemia.
In addition, some patients suffer from gastrointestinal complaints such as nausea, diarrhea and vomiting. Headaches and rashes on the skin are also possible.In addition, some people complain of dryness of the oral mucosa, thrombocytopenia, and leukopenia while taking it.
If the drug pyrimethamine is taken together with sulfones or sulfonamides, some other undesirable side effects are possible. These include, for example, dermatitis, photodermatoses, Lyell's syndrome and Stevens-Johnson syndrome.
If pyrimethamine is taken long-term, depression, drug fever, hepatotoxicity and agranulocytoses may appear. When administered in particularly high doses, the active ingredient pyrimethamine leads in some cases to tremors, seizures and ataxia. Neurotoxicity, circulatory collapse and stomatitis are also possible.
In addition, there are some contraindications to be aware of before taking the drug pyrimethamine for the first time. If pyrimethamine is prescribed in high doses, there is a risk of embryotoxicity. For this reason, the use of the active ingredient pyrimethamine during pregnancy should be carefully considered. The drug pyrimethamine is not the first choice for immunocompromised people either. In addition, taking it can lead to complications for people with biliary or liver problems.
If there is an existing hypersensitivity to the active ingredient pyrimethamine, therapy with the drug should be avoided in any case. Various possible interactions with other medicinal substances must also be taken into account during treatment. These are primarily folic acid antagonists, antacids and lorazepam.
In principle, regular blood tests are necessary during therapy. Among other things, the decrease in the number of pathogens is checked. It is the responsibility of the respective patient to report any symptoms and undesirable side effects that arise during therapy to a doctor. In some cases it is necessary to discontinue the drug pyrimethamine and find a more tolerated preparation or an alternative method of treatment for the patient.
