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Sulfadoxine / Pyrimethamine

Pronunciation: SUL-fa-DOX-een/PIR-i-METH-a-meen
Class: Antimalarial preparation

Trade Names:
- Tablets sulfadoxine 500 mg/pyrimethamine 25 mg


The 2 components sequentially block 2 enzymes involved in the biosynthesis of folinic acid within the parasites.

Indications and Usage

Treatment of acute, uncomplicated Plasmodium falciparum malaria for patients in whom chloroquine resistance is suspected; malaria prophylaxis for travelers to areas where chloroquine-resistant P. falciparum malaria is endemic and sensitive to sulfadoxine/pyrimethamine and when alternative therapy is not available or is contraindicated. Malaria prophylaxis with sulfadoxine/pyrimethamine is not routinely recommended.

Unlabeled Uses

Prophylaxis of Pneumocystis carinii infection.


Repeated prophylactic (prolonged) use in patients with severe renal or hepatic failure, or blood dyscrasias; documented megaloblastic anemia caused by folate deficiency; use in infants younger than 2 mo of age; prophylactic use in pregnancy at term and during lactation; hypersensitivity to pyrimethamine, sulfonamides, or any other ingredient of sulfadoxine/pyrimethamine.

Dosage and Administration

Malaria Prophylaxis

Take first dose 1 or 2 days before arrival in an endemic area; continue administration during the stay and for 4 to 6 wk after return.


PO 1 tablet once per wk or 2 tablets once every 2 wk.

Children older than 2 mo to 18 yr of age

PO Dosage is based on body weight.

More than 45 kg

Take 1½ tablets once weekly.

31 to 45 kg

Take 1 tablet once weekly.

21 to 30 kg

Take ¾ tablets once weekly.

11 to 20 kg

Take ½ tablet once weekly.

5 to 10 kg

Take ¼ tablet once weekly.


Take care in dose selection and monitor renal function.

Renal Impairment

Administer with caution to patients with renal function impairment.

Hepatic Impairment

Administer with caution to patients with hepatic function impairment.

Malaria Treatment

PO Single dose of 2 to 3 tablets.

Children older than 2 mo to 18 yr of age

PO Dosage is based on body weight.

More than 45 kg

Take 3 tablets as a single dose.

31 to 45 kg

Take 2 tablets as a single dose.

21 to 30 kg

Take 1½ tablets as a single dose.

11 to 20 kg

Take 1 tablet as a single dose.

5 to 10 kg

Take ½ tablets as a single dose.

General Advice

  • Prophylactic therapy should not be continued for more than 2 yr.


Store tablets at 68° to 77°F in a dry place.

Drug Interactions

Antifolic drugs (eg, sulfonamides, trimethoprim-sulfamethoxazole)

Should not be taken by patients receiving sulfadoxine/pyrimethamine.


Incidence and severity of adverse reactions may be increased compared with taking sulfadoxine/pyrimethamine alone.


May increase the potential for formation of insoluble precipitates in the urine.


Methotrexate levels may increase; adjust dose as needed.


May augment phototoxicity.

Laboratory Test Interactions

None well documented.

Adverse Reactions


Apathy; ataxia; convulsions; fatigue; hallucinations; headache; insomnia; mental depression; muscle weakness; nervousness; peripheral neuritis; polyneuritis; tinnitus; vertigo.


Erythema multiforme; exfoliative dermatitis; generalized skin eruptions; Lyell syndrome; photosensitization; pruritus; slight hair loss; Stevens-Johnson syndrome; toxic epidermal necrolysis (TEN); urticaria.


Conjunctival and scleral injection; periorbital edema.


Abdominal pain; diarrhea; emesis; feeling of fullness; glossitis; nausea; pancreatitis; stomatitis.


BUN and serum creatinine elevation; crystalluria; interstitial nephritis; renal failure; toxic nephrosis with oliguria and anuria.


Agranulocytosis; aplastic anemia; eosinophilia; hemolytic anemia; hypoprothrombinemia; leukopenia; megaloblastic anemia; methemoglobinemia; purpura; serum sickness; thrombocytopenia.


Hepatitis; hepatocellular necrosis; transient rise of liver enzymes.


Allergic myocarditis; allergic pericarditis.




Pulmonary infiltrates resembling eosinophilic or allergic alveolitis.


Anaphylactoid reactions; chills; drug fever; lupus erythematosus phenomenon; periarteritis nodosa.



Fatalities have occurred because of severe reactions, including Stevens-Johnson syndrome and TEN. Discontinue sulfadoxine/pyrimethamine prophylaxis at the first appearance of skin rash, if a significant reduction in the count of any formed blood elements is noted, or upon the occurrence of active bacterial or fungal infections.


Regularly schedule liver enzyme tests, analysis of urine for crystalluria, and CBCs whenever administration is for more than 3 mo.


Category C . Contraindicated in pregnancy at term (crosses placenta).


Excreted in breast milk (may cause kernicterus).


Should not be given to infants younger than 2 mo of age because of inadequate development of glucuronide-forming enzyme system.


Use with caution because of the greater frequency of decreased hepatic, renal, or cardiac function, and concomitant diseases or other drug therapy.

Special Risk Patients

Use with caution in patients with renal or hepatic function impairment, possible folate deficiency, severe allergy or bronchial asthma, or G-6-PD deficiency.


Avoid excessive sun exposure.

Folic acid deficiency

If signs of folic acid deficiency occur, discontinue treatment. When recovery of depressed platelets or WBC counts is too slow, folinic acid may be administered.

Severe reaction

Fatalities have occurred because of fulminant hepatic necrosis, agranulocytosis, aplastic anemia, and other blood dyscrasias.



Anorexia, CNS stimulation (including convulsions), crystalluria, glossitis, headache, leukopenia, megaloblastic anemia, nausea, thrombocytopenia, vomiting.

Patient Information

  • Advise patient to maintain adequate fluid intake (eg, 8 glasses of water/day) while taking medication.
  • Instruct patient taking medication for prophylaxis that first dose should be taken 1 to 2 days prior to arrival in malaria-infected area and that subsequent doses should be taken on the same day of the week (or every other week if ordered) while in the malaria-infected area and for 4 to 6 wk after leaving the malaria-infected area.
  • Advise patient that protective clothing, insect repellents, and bednets are important components of malaria prophylaxis.
  • Advise patient to discontinue therapy and notify health care provider immediately if any of the following occur: fever or other signs of infection (eg, sore throat), joint pain, paleness, skin discoloration, skin rash, tongue inflammation, unexplained cough or shortness of breath, yellowing of skin or eyes.
  • Advise patient to notify health care provider if severe or persistent vomiting or diarrhea develops, other bothersome side effects occur, or therapy is prematurely discontinued for any reason.
  • Advise women of childbearing potential against becoming pregnant or breast-feeding infants during treatment or prophylaxis.
  • Advise patient if a febrile illness develops during or after return from a malaria-endemic area to seek medical attention and inform health care provider of possible exposure to malaria.

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