SULPHAMETHOXYPYRAZINE IP 500mg + PYRIMETHAMINE BP 25mg
METAFIN TABLETS is available as oral tablets for adult and child patients.
Each tablet contains :
Sulphamethoxypyrazine I.P. 500 mg.
Pyrimethamine B.P. 25 mg.
METAFIN is a combination of long acting sulphonamide and an antimalarial and is used mainly in the treatment and prophylaxis of falciparum malaria resistant to other therapies (e.g. chloroquine)
PHARMACOLOGY & USES :
METAFIN is readily absorbed from the GI tract following an oral dose, and is only slowly excreted, the average half life in plasma being 90 hours for pyimethamine and 65 hours for sulphamethoxypyrazine. As the half life of Sulphamethoxypyrazine is shorter than Sulphadoxine (whose is upto 7 days) it has the advantage over Sulphadoxine, to be excreted earlier, in case any side effects occur.
Following administration of a single dose of 2 to 3 tablets it was bound to plasma proteins to the extent of 72 to 81% and peak concentration in the circulation are stated to occur about 2 hours after a dose is taken and further “could produce a blood concentration of 70ug per ml.” - R.L. Herting et al., Antimicrob. Ag. Chemother., 1964,554.
“Pyrimethamine interferes with the synthesis of folinic acid by the parasite. Sulphonamides and sulphones (Sulphamethoxypyrazine) act on the same biological pathway at a different point and therefore enhance the action of Pyrimethamine.” (Reference- Martindale the Extra Pharmacopoeia 28th Edition Page 403). This effect has been utilised in the supression and treatment of malaria due to most strains of Plasmodium including those resistant to chloroquine and pyrimethamine alone.
INDICATIONS AND USAGE :
METAFIN is indicated in :
- Treatment of Tough Malaria resistant to chloroquine and other therapies.
- Meningeal leukemia
- Suppression of falciparum and vivax malaria and other resistant malarias
DOSAGE & ADMINISTRATION :
- The recommended dosage of METAFIN in adults is 2 to 3 Tablets as a single dose. Dosage to be repeated after 1-2 weeks depending upon the immunity of the patient. For casual prophylaxis or suppression a single tablet is given every 7 days. A suggested weekly dose of children is :
upto 4 years - ¼ of adult dose
5-8 years - ½ of adult dose
9-12 years - ¾ of adult dose
1. Adequate fluid intake is necessary to reduce the risk of crystalluria .
2. Contra indicated in patients with impaired hepatic function and should be used with caution in renal impairement.
3. Should not be given in infants within 1-2 months of birth and contra indicated in nursing mothers.
4. The administration of folinic acid 10 mg. Daily has been recommended in order to prevent haemetological toxicity due to pyrimethamine when administered in very high doses.
Store in a cool, dry place away from direct heat and sunlight.
METAFIN is available as :
* Blister of Two Tablet