Drug interactions - summary

Sulphadoxine +

 Antifolic drugs eg. methotrexate/Sulfonamides/TMP- SMZ-                                                          concurrent pyrimethamine increase the risk of bone  marrow suppression . discontinue pyrimethimine if signs  of folate defeciency develop  

Chemophylaxis of malaria 

Insomnia, diarrhea, headache, lightheadedness, Dryness of the mouth or throat, fever, malaise, Dermatitis, abnormal skin pigmentation, Depression, seizures, pulmonary eosinophilia. Cardiac rhythm disorders. Anorexia, vomiting, vomting may minimised by giving with meals. Atrophic glossitis

Hypersensitivity. Megaloblastic anemia due to folate defiency.

Indications:

Chemoprophylaxis of malaria.

Dosage:

Adults and children (more than 10 years old)- 25mg once weekly Children(4 to 10 years old)- 12.5mg once weekly Infants and children(less than 4 years old)- 6.25mg once weekly

Pharmacology:

Pyrimethamine is a folic acid antagonist. Its therapetc action is based on differential requirement between host and parasite for nucleic acid precursors involved in growth as it selectively inhibits dihydrofolate reductase

Pharmacokinetics:

Well absorbed after oral use. Peak plasma concentrations occur in 2 to 6 hrs. Plasma half-life is 4days.

Can be taken with food

Pregnancy:

Co-administration with folinic acid is recommended.

Lactation:

Safety for use is not established. Because of the potential hazards to the nursing infant, decide whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.