Dosing and uses of Fansidar, Pyrimethamine-sulfadoxine (pyrimethamine/sulfadoxine)
Adult dosage forms and strengths
tablet
- 25mg/500mg
Malaria Treatment
Discontinued in the United States
2-3 tablet PO once
Malaria Prophylaxis
1 tablet qWeek OR 2 tablets q2Weeks
Administration
Swallow tablet whole with plenty of fluids after a meaL
Maintain adequate fluid intake to avert crystalluria or stone formation
Prophylaxis: take 1st dose 1-2 days before arrival to endemic area, continue throughout stay & 4-6 weeks after return
Other Indications & Uses
Chloroquine-resistant P. falciparum malaria treatment & prophylaxis
Off-label: toxoplasmosis
Pediatric dosage forms and strengths
tablet
- 25mg/500mg
Malaria Treatment
Discontinued in the United States
5-10 kg: 0.5 tablet
11-20 kg: 1 tablet
21-30 kg: 1.5 tablet
31-45 kg: 2 tablet
>45 kg: 3 tablet
Malaria Prophylaxis
5-10 kg: 0.25 tablet
11-20 kg: 0.5 tablet
21-30 kg: 0.75 tablet
31-45 kg: 1 tablet
>45 kg: 1.5 tablet
Administration
Swallow tablet whole with plenty of fluids after a meaL
Maintain adequate fluid intake to avert crystalluria or stone formation
Prophylaxis: give 1st dose 1-2 days before arrival to endemic area, continue throughout stay & 4-6 weeks after return
<2 months old: Safety & efficacy not established
>2 months old: All PO single dose
Fansidar, Pyrimethamine-sulfadoxine (pyrimethamine/sulfadoxine) adverse (side) effects
Frequency not defined (selected)
Agranulocytosis
Anemias
Insomnia
Lightheadedness
Malaise
Seizures
Abnl skin pigmentation
Dermatitis
Erythema multiforme
Rash
Stevens-Johnson syndrome
TEn
Anorexia
N/V
Diarrhea
Leukopenia
Thrombocytopenia
Pulmonary eosinophilia
Renal failure
Interstitial nephritis
Toxic nephrosis
Warnings
Contraindications
Hypersensitivity to sulfonamides, pyrimethamine
Folate deficiency megaloblastic anemia
Prophylactic use during third trimester of pregnancy/nursing mother
Repeated prophylactic use in renal/hepatic failure, blood dyscrasias
<2 mo
Cautions
Asthma, epilepsy, hepatic/renal impairment, G-6-PD deficiency
Risk of Stevens-Johnson syndrome & toxic epidermal necrolysis (TEN)
- discontinue STAT if skin rash appears
Significant levels of resistant strains in many parts of the world
Avoid prolonged sun exposure
Not routinely used for prophylaxis
Pregnancy and lactation
Pregnancy category: C
Lactation: enters breast milk, contraindicated
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Fansidar, Pyrimethamine-sulfadoxine (pyrimethamine/sulfadoxine)
Protein Bound: pyrimethamine 87%; sulfadoxine 90%
Half-Life:
Pyrimethamine: 96 hr
Sulfadoxine: ~200 hr
Peak Plasma (1 tab dose)
Time: 4 hr
Concentration: Pyr: 0.2 mg/L; Sulf: 60 mg/L
Other Information
Metabolism: liver
Excretion: urine
Mechanism of action
Folic acid antagonists
