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|Sulfadoxine/Pyrimethamine

Sulfadoxine/Pyrimethamine

Trade Names:
Fansidar
- Tablets 500 mg sulfadoxine and 25 mg pyrimethamine

Mechanism of Action

Pharmacology

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

Indications and Usage

Treatment of Plasmodium falciparum malaria for those patients in whom chloroquine resistance is suspected; prophylaxis of malaria for travelers to areas where chloroquine-resistant P. falciparum malaria is endemic.

Contraindications

Patients with severe renal insufficiency; marked liver parenchymal damage; blood dyscrasias; documented megaloblastic anemia caused by folate deficiency; infants less than 2 mo; pregnancy at term; during the nursing period; hypersensitivity to pyrimethamine, sulfonamides, or any component of the product.

Dosage and Administration

PO Single dose of 2 to 3 tablets.

PO Single dose of 2 tablets.

PO Single dose of 1 tablet.

PO Single dose of ½ tablet.

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

PO 1 tablet once/wk or 2 tablets once q 2 wk.

PO ¾ tablet once/wk or 1½ tablets once q 2 wk.

PO ½ tablet once/wk or 1 tablet once q 2 wk.

PO ¼ tablet once/wk or ½ tablet once q 2 wk.

Storage/Stability

Store tablets at controlled room temperature (59° to 77°F).

Drug Interactions

Should not be taken by patients receiving sulfadoxine/pyrimethamine.

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

Laboratory Test Interactions

None well documented.

Adverse Reactions

CNS

Headache; peripheral neuritis; mental depression; convulsions; ataxia; hallucinations; insomnia; apathy; fatigue; muscle weakness; nervousness; vertigo.

EENT

Tinnitus.

GI

Glossitis; stomatitis; nausea; emesis; abdominal pain; diarrhea; pancreatitis.

Genitourinary

Toxic nephrosis with oliguria and anuria.

Hematologic

Agranulocytosis; aplastic anemia; megaloblastic anemia; thrombopenia; leukopenia; hemolytic anemia; purpura; hypoprothrombinemia; methemoglobinemia; eosinophilia.

Hepatic

Hepatitis; hepatocellular necrosis.

Respiratory

Pulmonary infiltrates.

Miscellaneous

Allergic reactions including erythema multiforme, Stevens-Johnson syndrome, generalized skin eruptions, toxic epidermal necrolysis, urticaria, serum sickness, pruritus, exfoliative dermatitis, anaphylactoid reactions, periorbital edema, conjunctival and scleral injection, photosensitization, arthralgia and allergic myocarditis; drug fever; chills; periarteritis nodosa; lupus erythematosus.

Precautions

Pregnancy

Category C . Contraindicated in pregnancy at term (may cross placenta, causing kernicterus).

Lactation

Secreted in breast milk (may cause kernicterus).

Children

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

Elderly

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 impaired renal or hepatic function, possible folate deficiency, severe allergy or bronchial asthma, or glucose-6-phosphate dehydrogenase deficiency.

Severe reaction

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

Overdosage

Symptoms

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

Patient Information

• Explain name, dose, action, and potential side effects of drug.
• 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: skin rash; fever or other signs of infection (eg, sore throat); joint pain; unexplained cough or shortness of breath; paleness; skin discoloration; yellowing of skin or eyes; tongue inflammation.
• Advise patient to notify health care provider if severe or persistent vomiting or diarrhea develop, other bothersome side effects occur, or if therapy is prematurely discontinued for any reason.
• Advise women of childbearing potential to use effective contraception while taking medication for malaria prophylaxis.
• Advise women to notify health care provider if pregnant, planning to become pregnant, or breastfeeding.
• Instruct patient not to take any prescription or OTC medications or dietary supplements unless advised by health care provider.
• Advise patient if a febrile illness develops during or after return from a malaria-endemic area to seek health care and inform health care provider of possible exposure to malaria.