Astab

Uses

Treatment of all forms of malaria due to Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae. The drug is also used for suppressive or prophylactic management, particularly in areas where resistance to chloroquine is known to exist.

Astab is also used to associated treatment for these conditions: Plasmodium Infections, Toxoplasmosis, Acute Malaria

How Astab works

Pyrimethamine inhibits the dihydrofolate reductase of plasmodia and thereby blocks the biosynthesis of purines and pyrimidines, which are essential for DNA synthesis and cell multiplication. This leads to failure of nuclear division at the time of schizont formation in erythrocytes and liver.

Dosage

Astab dosage

Curative treatment of malaria with a single dose-

• Adults: 2-3 tablets
• Children under 4 years: ½ tablets
• 4-8 years: 1 tablet
• 9-14 years: 2 tablets

In severe cases, Sulphadoxine & Pyrimethamine can be beneficially combined with quinine.

Suppressive or prophylactic management-

The dose given below should be taken at one time:For semi-immune subjects (

Dose: once every four weeks)-

• Adults: 2-3 tablets
• Children under 4 years: ½ tablets
• 4-8 years: 1 tablet
• 9-14 years: 2 tablets

For non-immune subjects (

Dose: Once every two weeks)-

• Adults: 2 tablets
• Children under 4 years: 1½ tablets
• 4-8 years: 1 tablet
• 9-14 years: 1½ tablets

For malaria prophylaxis:The first dose of Sulphadoxine & Pyrimethamine should be taken one or two days before departure for an endemic area in order to protect tolerance, administration should be continued in the above dosage during the stay and also for four weeks after return or as prescribed by the physician.

Side Effects

Sulphadoxine & Pyrimethamine at the recommended dose is well tolerated. Main side effects are given below

• Skin reactions: Drug rash, pruritus and slight hair loss have been observed.
• Gastro-intestinal reactions: Feeling of fullness, nausea, rarely vomiting, stomatitis.
• Haematological reactions: In rare cases, leukopenia, thrombocytopenia, and megaloblastic anemia have been observed.
• Other reactions: Fatigue, headache, fever, polyneuritis may occasionally occur.

Precaution

Impaired renal or hepatic function, folate deficiency, severe allergy or bronchial asthma, G6PD deficiency, pregnancy. Take with plenty of water to prevent crystalluria. Avoid excessive exposure to sun. Discontinue at the first sign of rash. Discontinue if signs of folic acid deficiency develops. Regular CBC monitoring, LFT, analysis of urine for crystalluria when admin for > 3 mth. Take with food to minimise Gi effects (e.g. anorexia and vomiting).

Interaction

Concurrent administration of other preparations containing folate antagonists (e.g. cotrimoxazole, methotrexate, anticonvulsants) can result in increased impairment of folic acid metabolism, which leads to haematological side effects.

Elimination Route

Well absorbed with peak levels occurring between 2 to 6 hours following administration

Half Life

96 hours

Pregnancy & Breastfeeding use

Sulphadoxine & Pyrimethamine is contraindicated during pregnancy, premature and newborn infants during the first weeks of life and intolerance to sulfonamide. If pregnancy can not be excluded, possible risks should be balanced against therapeutic effect.

Both Pyrimethamine and Sulphadoxine are excreted in maternal breast milk. Nursing mother should not take Astab.

Contraindication

Prophylactic (repeated) use of Pyrimethamine + Sulphadoxine is contraindicated in patients with severe renal insufficiency, marked liver parenchymal damage or blood dyscrasias. Treatment must be immediately discontinued upon the appearance of any mucocutaneous signs or symptoms such as pruritus, erythema, rash, orogenital lesions or pharyngitis.

Special Warning

Renal Impairment: Dose reduction may be needed. Severe: contra-indicated.

Hepatic Impairment: Dose reduction may be needed. Severe: contra-indicated.

Acute Overdose

Symptoms: Headache, nausea, anorexia, vomiting, CNS stimulation, megaloblastic anaemia, leukopenia, thrombocytopenia, glossitis and crystalluria.

Management: Treatment is symptomatic and supportive. Emesis and gastric lavage to reduce drug absorption. Ensure that patient is adequately hydrated to prevent kidney damage. Monitor renal, hepatic, and haematopoietic systems for at least 1 month after overdosage. Folinic acid may be admin for depressed platelet or WBC counts.

Innovators Monograph

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