Pyrimethamine tablets, the indication is that this product is mainly used for the prevention of malaria, and can also be used for the treatment of toxoplasmosis.
1.Ingredients: The main ingredient of this product is pyrimethamine.
2.Properties: This product is a white tablet.
3.Indications: This product is mainly used for the prevention of malaria, and can also be used for the treatment of toxoplasmosis.
4.Specification: 6.25mg
5.Usage: Oral administration
6.Dosage:
The usual amount for adults
(1) Preventive medication should be taken 1 to 2 weeks before entering the epidemic area, and generally should be taken until 6 to 8 weeks after leaving the epidemic area, and 4 tablets per week;
(2) Plasmodium falciparum caused by chloroquine-resistant strains, 2 tablets a day, divided into 2 doses, and a course of treatment for 3 days;
(3) For the treatment of toxoplasmosis, take 50-100 mg daily for 1-3 days (depending on tolerance), then take 25 mg daily for 4-6 weeks.
Pediatric dosage
(1) Prophylactic medication, 0.9 mg/kg of body weight at a time, once a week, and the maximum dose is limited to the adult dose;
(2) Plasmodium falciparum caused by chloroquine-resistant strains, each time is 0.3 mg/kg of body weight, 3 times a day, and the course of treatment is 3 days;
(3) Toxoplasmosis: 1 mg/kg of body weight per day, divided into 2 doses. After 1 to 3 days of administration, it was changed to 0.5 mg/kg per day, divided into 2 doses, and the course of treatment was 4 to 6 weeks.
7.Adverse reactions
Oral administration of general antimalarial therapeutic doses has low toxicity and is relatively safe. When high-dose application, such as daily use of 25mg for more than a month, there will be a lack of folic acid. It mainly affects tissues that grow and reproduce rapidly, such as bone marrow and gastrointestinal mucosa, causing hematopoietic function and gastrointestinal symptoms, such as change or loss of taste, tongue pain, redness, burning and acupuncture, oral ulcers, leukoplakia, etc., esophagus Dysphagia, nausea, vomiting, abdominal pain, diarrhea, etc. caused by inflammation. The more serious ones are giant cell anemia, leukopenia, etc. If the drug is stopped early, it can recover on its own. Leucovorin improves bone marrow function. Skin erythema due to allergies is less common.
8.Taboo
1. Pregnant women are prohibited. Animal experiments have shown that this product can cause fetal malformations.
2. Breastfeeding women are also prohibited, because this product can be excreted in milk, interfere with the baby's folic acid metabolism, if the baby has glucose-6-phosphate dehydrogenase (G-6-PD) deficiency, it can cause hemolytic anemia.
9.Precautions
1. The following situations should be used with caution;
(1) Consciousness disturbance, high doses of toxoplasmosis can cause central nervous system toxicity and interfere with folic acid metabolism;
(2) For G-6-PD deficiency, taking this product may cause hemolytic anemia;
(3) In patients with giant cell anemia, taking this product can affect the metabolism of folic acid.
2. During high-dose treatment, leukocytes and platelets should be detected twice a week.
3. Pregnant and lactating women are prohibited.
10.Children's medication: overdose can easily cause acute poisoning.
11.Drug overdose
Overdose of pyrimethamine can cause acute poisoning symptoms, which are more likely to occur in children. The fragrance of this medicine can be mistaken for candy by children and cause poisoning accidents. Nausea and vomiting, stomach burning, mouth and mouth may occur within 1 to 2 hours after overdose. Thirst, palpitations, irritability, etc. In severe cases, dizziness, blurred vision, paroxysmal convulsions, convulsions, coma, and death may occur. This is caused by the direct toxic effect of the drug on the central nervous system.
12.Pharmacology and Toxicology
Pyrimethamine has an inhibitory effect on the infrared phase of some falciparum malaria and Plasmodium vivax, and the inhibitory effect on the red endogenous phase is limited to the immature schizont stage, which can inhibit the division of trophozoites. Plasmodium cannot use folic acid in the environment, but must synthesize it by itself. Pyrimethamine is an inhibitor of dihydrofolate reductase, so that dihydrofolate cannot be reduced to tetrahydrofolate, which in turn affects purine and pyrimidine nucleotides Finally, the synthesis of nucleic acid is reduced, the division of the nucleus and the reproduction of Plasmodium are inhibited. The DNA synthesis of Plasmodium mainly occurs in the trophozoite stage, and it is rarely synthesized in the schizont stage, so pyrimethamine mainly acts on the Plasmodium that is undergoing fission proliferation, but is invalid for the schizont that has been developed.
13.Pharmacokinetics
After oral administration, the intestinal absorption is slow but complete, and the plasma concentration reaches a peak within 6 hours, and its antifolate effect can last for more than 48 hours. Mainly distributed in red and white blood cells and lung, liver, kidney, spleen and other organs. This product can pass through the placenta and is slowly excreted by the kidneys. About 10% to 20% of the prototype substance is excreted from the urine within 5 to 7 days after taking the medicine, which can last for more than 30 days. This product can also be excreted in breast milk, and only a small amount is excreted in feces. t1/2β is 80 to 100 hours. When the plasma concentration is 10-100 mg/L, it can inhibit the blood schizont of the susceptible strain of Plasmodium falciparum.
14.Storage: shading, sealed preservation.
