Pyrimethamine

Pyrimethamine is oral antimalarial agent. Pyrimethamine is a folic acid antagonist and dihydrofolate reductase inhibitor. Pyrimethamine is 2,4-diaminopyrimidine related to trimethoprim.


Adult Dose
Dose: 25 mg
Single Dose: 25 (25)
Frequency: As recommended.
Route: PO
Instructions: Once in a Week
Neonatal
Paedriatic
Dose: 0.5 mg/kg
Single Dose: 0.5 (0.5)
Frequency: 24 hourly
Route: Oral
Instructions: Double dose for 1st 3 days
Characteristics
. It is of Synthetic origin and belongs to Pyrimidine. It belongs to Dihydrofolate reductase inhibitor pharmacological group on the basis of mechanism of action and also classified in Antimalarial Agent pharmacological group.The Molecular Weight of Pyrimethamine is 248.70. Its pKa is 7.3.
Contraindications
Pyrimethamine is contraindicated in conditions like Anaemia.
Effects
The severe or irreversible adverse effects of Pyrimethamine, which give rise to further complications include Megaloblastic anemia.Pyrimethamine produces potentially life-threatening effects which include Agranulocytosis, Disseminated intravascular coagulation. which are responsible for the discontinuation of Pyrimethamine therapy.The signs and symptoms that are produced after the acute overdosage of Pyrimethamine include Tachycardia, Coma, Fever, Blindness, Deafness, Dyspnea.The symptomatic adverse reactions produced by Pyrimethamine are more or less tolerable and if they become severe, they can be treated symptomatically, these include Rashes, Photosensitivity reactions.
Indications
Pyrimethamine is primarily indicated in conditions like Malaria, Malaria prophylaxis, Malaria treatment, Protozoa infection, Toxoplasmosis.
Interactions
Pyrimethamine is known to interact with other drugs, the details of drug interactions is as follows:DrugDetailsSeverityOnsetManagementChloroquineCo-TrimoxazoleCo-TrimoxazoleDapsoneLorazepamMethotrexateThis combination will increase the risk of bone marrow depression.ModeratePeriodic monitoring for folic acid deficiency and bone marrow depression is recommended.SulphadiazineTrimethoprimTrimethoprim These interactions are sometimes beneficial and sometimes may pose threats to life. Always consult your physician for the change of dose regimen or an alternative drug of choice that may strictly be required.
Interfrence
Complete blood cell count
Risks
Drug should not be given to Paediatrics, patients suffering from Kidney dysfunction, patients suffering from Liver Malfunction, Geriatrics, and Neonates.If prescribing authority justifies the benefits of the drug against the possible damages he/she should reevaluate them and consult the reference material and previous studies.
Storage
Tab Store in a well closed container, Below 40°C. Protect from Sunlight.
Warnings
Pyrimethamine should be used only if clearly needed during pregnancy or lactation. It should be used with caution in patients with any pre-existing kidney disease, liver disease, blood disorders or any allergy.
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