Hangzhou Excelente Chemicals Co., Ltd.  

Product Name: Pyrimethamine USP Good Quality and Price Model NO.: USP/BP Purity: >99% State: Solid Suitable for: Elderly, Children, Adult Certification: ISO 9001, USP Customized: Non-Customized Powder: Yes Trademark: Excelente Transport Package: 25kg/Drum Specification: USP/BP Origin: Zhejiang HS Code: 2933599090 Product Description Product descriptionPyrimethamine is a diaminopyrimidine which is structurally related to trimethoprim. It is effective against erythrocytic stage of Plasmodium (P) falciparum and less so against P. vivax, P. ovale and P. malariae. Pyrimethamine also inhibits the sporogony in the mosquito, resulting in a decrease of transmission of the infection within the community[1].The mechanism of action of pyrimethamine is related to its inhibition of dihydrofolic reductase necessary for the folic acid synthesis in the parasite. Pyrimethamine acts slowly and is not recommended as monotherapy for acute malaria attacks. Resistance to pyrimethamine developed soon when the drug was used on a large scale as monoprophylaxis[1]. In resistant strains, the enzyme dihydrofolic reductase binds to pyrimethamine several hundred times less than in sensitive strains[2]. This high grade resistance is probably a onestep mutation and cannot be overcome by increasing the dose. However, when combined with long-acting sulphonomides (sulphadoxine), the effect of pyrimethamine is potentiated and the risk of developing resistant strains is far less.ApplicationFor the treatment of toxoplasmosis and acute malaria; For the prevention of malaria in areas non-resistant to pyrimethamine.Pyrimethamine is a dihydrofolate reductase inhibitor, like the biguanides, and is structurally related to trimethoprim. It is seldom used alone. Pyrimethamine in fixed combinations with dapsone or sulfadoxine is used for treatment and prophylaxis of chloroquine-resistant falciparum malaria. The synergistic activities of pyrimethamine and sulfonamides are similar to those of trimethoprim/sulfonamide combinations. Resistant strains of Plasmodium falciparum have appeared world wide. Prophylaxis against falciparum malaria with pyrimethamine alone is therefore not recommended. Most strains of Plasmodium vivax have remained sensitive. Pyrimethamine is also used in combination with a sulfonamide for the treatment of Toxoplasmosis. It is slowly absorbed from the gastrointestinal tract with peak plasma levels 4-6 hours after dosing. Pyrimethamine is bound to plasma proteins and is extensively metabolized before excretion. Its elimination half-life is 3-5 days.Package25kg/drumSpecificationItem nameStandardCharacteristicsWhite or off whitepowderIdentification PositiveClarity and color of solution2.5% W/V mixed solution is clear; color≤BY6Acidity and alkalinityRequires 0.01M sodium hydroxide VS not more than 0.2ml and 0.01M hydrochloric acid VS not more than 0.4mlRelated substancesAny second spot in solution 1.0% W/V is not more than 0.25%Sulphate≤80ppmMelting point238-242ºCLoss on drying≤0.50%Ash ≤0.1%Assay(on dry basis)99.0-101.0%