Sulfamethoxazole + Trimethoprim


Concise Prescribing Info
Indications/Uses
Listed in Dosage.
Dosage/Direction for Use
Adult : PO/IV UTI; Acute exacerbations of chronic bronchitis; Acute otitis media 960 mg bid. Severe infections: 2.88 g/day in 2 divided doses. Pneumocystis (carinii) jiroveci pneumonia 120 mg/kg/day in 2-4 divided doses for 14-21 days. Prophylaxis of Pneumocystis (carinii) jiroveci pneumonia 960 mg once daily for 7 days; 960 mg once daily 3 times wkly on alternate days; or 960 mg bid 3 times wkly on alternate days.
Dosage Details
Intravenous
Acute exacerbations of chronic bronchitis, Acute otitis media, Urinary tract infections
Adult: Each ampoule contains sulfamethoxazole 400 mg and trimethoprim 80 mg in 5 mL: 960 mg bid. Severe infections: 2.88 g daily in 2 divided doses.
Child: 18 mg/kg 12 hrly. Severe infections: Up to 27 mg/kg 12 hrly. Max: 1.44 g 12 hrly.

Intravenous
Pneumocystis (carinii) jirovecii pneumonia
Adult: Each ampoule contains sulfamethoxazole 400 mg and trimethoprim 80 mg in 5 mL: 120 mg/kg daily in 2-4 divided doses by infusion over 60-90 min for 14-21 days.
Child: ≥4 wk Same as adult dose.

Intravenous
Prophylaxis of Pneumocystis (carinii) jirovecii pneumonia
Adult: Each ampoule contains sulfamethoxazole 400 mg and trimethoprim 80 mg in 5 mL: 960 mg once daily for 7 days; 960 mg once daily 3 times wkly on alternate days; or 960 mg bid 3 times wkly on alternate days. Doses are given by infusion over 60-90 min.
Child: ≥4 wk 15-30 mg/kg bid, by infusion over 60-90 min, 2-3 times wkly given on consecutive or alternate days.

Oral
Acute exacerbations of chronic bronchitis, Acute otitis media, Urinary tract infections
Adult: Each tab contains sulfamethoxazole 400 mg or 800 mg and trimethoprim 80 mg or 160 mg; each 5 mL of oral susp contains sulfamethoxazole 200 mg and trimethoprim 40 mg: 960 mg bid. Severe infections: 2.88 g daily in 2 divided doses.
Child: 6 wk to 5 mth 120 mg bid; 6 mth to 5 yr 240 mg bid; 6-11 yr 480 mg bid.

Oral
Pneumocystis (carinii) jirovecii pneumonia
Adult: Each tab contains sulfamethoxazole 400 mg or 800 mg and trimethoprim 80 mg or 160 mg; each 5 mL of oral susp contains sulfamethoxazole 200 mg and trimethoprim 40 mg: 120 mg/kg daily in 2-4 divided doses for 14-21 days.
Child: ≥4 wk Same as adult dose.

Oral
Prophylaxis of Pneumocystis (carinii) jirovecii pneumonia
Adult: Each tab contains sulfamethoxazole 400 mg or 800 mg and trimethoprim 80 mg or 160 mg; each 5 mL of oral susp contains sulfamethoxazole 200 mg and trimethoprim 40 mg: 960 mg once daily for 7 days; 960 mg once daily 3 times wkly on alternate days; or 960 mg bid 3 times wkly on alternate days.
Child: ≥4 wk 15-30 mg/kg bid, 2-3 times wkly given on consecutive or alternate days.
Renal Impairment
CrCl (mL/min) Dosage
<15 Not recommended.
15-30 Half the standard dose.
Hepatic Impairment
Severe: Contraindicated.
Administration
Should be taken with food.
Reconstitution
Dilute each 5 mL of concentrate in 125 mL of dextrose in water 5%. In patients w/ fluid restriction, each 5 mL of the concentrate may be diluted in 75 mL of dextrose 5%.
Incompatibility
Y-site: Caspofungin, fluconazole, midazolam, pantoprazole, vinorelbine.
Contraindications
Known hypersensitivity to trimethoprim or sulfonamides; severe hepatic failure or marked liver parenchymal damage, jaundice; serious haematological disorders and porphyria; severe renal insufficiency where repeated measurements of the plasma concentration cannot be performed; history of drug-induced immune thrombocytopenia w/ use of trimethoprim and/or sulfonamides; megaloblastic anaemia due to folate deficiency. Neonates <6 wk, except for the treatment/prophylaxis of P. jiroveci in infants ≥4 wk. Treatment of Group A β-haemolytic streptococcia. Pregnancy, esp in the period prior to birth. Concomitant use w/ clozapine. Concomitant use w/ leucovorin for the treatment of P. jiroveci in HIV positive patients.
Special Precautions
Patient w/ severe allergy, bronchial asthma, thyroid dysfunction. Renal and mild to moderate hepatic impairment. Lactation.
Adverse Reactions
Allergic myocarditis, erythema multiforme, exfoliative dermatitis, angioedema, drug fever, chills, Henoch-Schoenlein purpura, serum sickness-like syndrome, generalised allergic reactions, generalised skin eruptions, photosensitivity, conjunctival and scleral inj, pruritus, urticaria, rash, periarteritis nodosa, SLE; elevated serum transaminase and bilirubin, pseudomembranous enterocolitis, pancreatitis, stomatitis, glossitis, nausea, emesis, abdominal pain, diarrhoea, anorexia; renal failure, interstitial nephritis, elevated BUN and serum creatinine, toxic nephrosis w/ oliguria and anuria; hyperkalaemia; aseptic meningitis, convulsions, peripheral neuritis, ataxia, vertigo, tinnitus, headache; hallucinations, depression, apathy, nervousness; dieresis, hypoglycaemia; arthralgia, myalgia; rhabdomyolysis; cough, shortness of breath, pulmonary infiltrates; weakness, fatigue, insomnia; QT prolongation, haemolysis, impaired phenylalanine metabolism.
Potentially Fatal: Severe skin, hepatic and blood disorders, aplastic anaemia, hypersensitivity of the resp tract; Stevens-Johnson syndrome, toxic epidermal necrolysis; Clostridium difficile-associated diarrhoea; severe and symptomatic hyponatraemia.
IV/Parenteral/PO: D
MonitoringParameters
Monitor CBC, serum K, creatinine, BUN.
Overdosage
Symptoms: Dizziness, nausea, vomiting, rashes, headache, ataxia, drowsiness, dysuria, facial swelling, weakness and confusion, bone marrow depression, slight elevations of serum aminotransferases. Management: Supportive and symptomatic treatment. Empty stomach immediately by inducing emesis or by lavage. Observe the patient for at least 4 hr and monitor urea and electrolytes w/ FBC. Give fluids to maintain a good urine output. May give Ca leucovirin 5-10 mg/day to counteract any adverse effects of trimethoprim on bone marrow or Ca folinate 3-6 mg for 5-7 days orally or by IM inj.
Drug Interactions
May increase risk of hyperkalaemia w/ ACE inhibitors. Increased risk of methaemoglobinaemia w/ prilocaine. May increase risk of ventricular arrhythmias w/ amiodarone. May increase dofetilide-induced QT prolongation. May increase risk of dapsone toxicity. May increase risk of crystalluria w/ methenamine. May increase serum rifampicin levels. Enhanced effects of acenocoumarol and warfarin. Enhanced effect of sulfonylureas. May prolong the half-life of phenytoin. May increase risk of megaloblastic anaemia w/ pyrimethamine given in doses of >25 mg wkly. May increase plasma concentrations of lamivudine, zidovudine and zalcitabine. Increased plasma concentrations w/ procainamide and/or amantadine. May increase risk of haematological toxicity w/ mercaptopurine and azathioprine. May increase digoxin levels. Increased risk of thrombocytopenia w/ diuretics. Potassium aminobenzoate may inhibit the effects of sulfonamides. Concomitant use w/ ciclosporin following renal transplantation may result to reversible deterioration of renal function.
Potentially Fatal: Increased risk of fatal agranulocytosis w/ clozapine. Concomitant use w/ leucovorin for the treatment of P. jiroveci in HIV positive patients may result to treatment failure and excess mortality.
Lab Interference
May interfere w/ serum-methotrexate assay and Jaffe alkaline picrate reaction assay for creatinine.
Action
Description: Sulfamethoxazole interferes w/ bacterial folic acid synthesis and growth via inhibition of dihydrofolic acid formation from paraaminobenzoic acid; trimethoprim inhibits dihydrofolic acid reduction to tetrahydrofolate resulting in sequential inhibition of enzymes of the folic acid pathway.
Pharmacokinetics:
Absorption: Readily and well absorbed from the GI tract. Time to peak plasma concentration: 1-4 hr (oral).
Distribution: Widely distributed into body tissues and fluids, including sputum, aqueous humor, middle ear fluid, prostatic fluid, vag fluid, bile and CSF. Crosses the placenta and enters breast milk. Plasma protein binding: Approx 70% (sulfamethoxazole); approx 45% (trimethoprim).
Metabolism: Sulfamethoxazole: Converted to the inactive N4-acetyl derivative via conjugation and to hydroxylamine via oxidation. Trimethoprim: Hepatic (approx 10-20%).
Excretion: Via urine (approx 50% as unchanged drug). Plasma half-life: Approx 6-12 hr (sulfamethoxazole); approx 8-10 hr (trimethoprim).
Chemical Structure

Chemical Structure Image
Sulfamethoxazole

Source: National Center for Biotechnology Information. PubChem Database. Sulfamethoxazole, CID=5329, https://pubchem.ncbi.nlm.nih.gov/compound/Sulfamethoxazole (accessed on Jan. 23, 2020)


Chemical Structure Image
Trimethoprim

Source: National Center for Biotechnology Information. PubChem Database. Trimethoprim, CID=5578, https://pubchem.ncbi.nlm.nih.gov/compound/Trimethoprim (accessed on Jan. 23, 2020)

Storage
Store between 15-30°C. Protect from light and moisture.
References
Anon. Sulfamethoxazole and Trimethoprim. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 20/02/2015.

Bactrim Tablet and Bactrim DS (Double-Strength) Tablet. U.S. FDA. https://www.fda.gov/. Accessed 20/02/2015.

Buckingham R (ed). Co-trimoxazole. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. http://www.medicinescomplete.com. Accessed 20/02/2015.

Buckingham R (ed). Sulfamethoxazole. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. http://www.medicinescomplete.com. Accessed 20/02/2015.

Buckingham R (ed). Trimethoprim. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 20/02/2015.

McEvoy GK, Snow EK, Miller J et al (eds). Co-trimoxazole. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). http://www.medicinescomplete.com. Accessed 20/02/2015.

Sulfamethoxazole and Trimethoprim (Double Strength) Tablet (Teva Pharmaceuticals USA Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 20/02/2015.

Sulfamethoxazole and Trimethoprim Injection, Solution (Teva Parenteral Medicines, Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 20/02/2015.

Sulfamethoxazole and Trimethoprim Suspension (Aurobindo Pharma Limited). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 20/02/2015.

Disclaimer: This information is independently developed by MIMS based on Sulfamethoxazole + Trimethoprim 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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