Sulfadoxine + Pyrimethamine


Concise Prescribing Info
Indications/Uses
Acute attack of chloroquine-resistant falciparum malaria.
Dosage/Direction for Use
Adult : PO Per tab contains sulfadoxine 500 mg and pyrimethamine 25 mg: 2-3 tabs as a single dose. Do not repeat w/in 7 days.
Dosage Details
Oral
Chloroquine resistant falciparum malaria acute attack
Adult: Per tab contains pyrimethamine 25 mg and sulfadoxine 500 mg: 2-3 tabs as a single dose. Do not repeat for at least 7 days.
Child: Pyrimethamine 25mg + Sulfadoxine 500mg (Tablet): <2 yr (5-10 kg): ½ tab as a single dose; 2-5 yr (>10-20 kg): 1 tab as a single dose; 5-10 yr (< 20-30 kg): 1½ tab as a single dose; 10-14 yr (> 30-45 kg): 2 tab as a single dose. Do not repeat for at least 7 days.
Renal Impairment
Dose reduction may be needed. Severe: contra-indicated.
Hepatic Impairment
Dose reduction may be needed. Severe: contra-indicated.
Administration
Should be taken with food. Take w/ plenty of fluids. Swallow whole, do not chew/crush.
Contraindications
Severe renal or hepatic impairment, blood dyscrasias, hypersensitivity to components, megaloblastic anaemia due to folate deficiency, pregnancy at term and during lactation, infants ≤ 2 mth old.
Special Precautions
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).
Adverse Reactions
Urticaria, serum sickness, photosensitisation, arthralgia, nausea, vomiting, abdominal pain, diarrhoea, headache, peripheral neuritis, ataxia, tinnitus, vertigo, convulsions, toxic nephrosis and pulmonary infiltrates resembling eosinophilic or allergic alveolitis.
Potentially Fatal: Stevens-Johnson syndrome, toxic epidermal necrolysis, fulminant hepatic necrosis, blood dyscrasias, anaphylactoid reactions.
Overdosage
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.
Drug Interactions
Increased halofantrine and chlorpromazine levels. Increased effects of warfarin.
Potentially Fatal: Increased risk of myelosupression with zidovudine, clozapine.
Action
Description: Pyrimethamine, a folic acid antagonist, inhibits the reduction of dihydrofolic acid to tetrahydrofolic acid (folinic acid). Sulfadoxine, a structural analog of p-aminobenzoic acid (PABA), competitively inhibits dihydrofolic acid synthesis which is important for PABA conversion to folic acid. This combination results in a synergistic action against susceptible plasmodia. Both have prolonged half-lives enabling single dose admin.
Pharmacokinetics:
Absorption: Peak plasma concentration: 4 hr.
Distribution: Volume of distribution: 0.14 L/kg (sulfadoxine); 2.3 L/kg (pyrimethamine). Protein binding: 90% (for both drugs). Both drugs cross placenta and passes into breast milk.
Metabolism: Sulfadoxine: 5% appear in blood as acetylated metabolite, 2-3% as glucuronide. Pyrimethamine converted to several metabolites.
Excretion: Elimination half life: 100 hr (pyrimethamine); 200 hr (sulfadoxine). Excreted mainly via kidneys.
MIMS Class
Disclaimer: This information is independently developed by MIMS based on Sulfadoxine + Pyrimethamine from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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