Sulfamethoxazole + Trimethoprim


Generic Medicine Info
Indications and Dosage
Intravenous
Acute exacerbations of chronic bronchitis, Acute uncomplicated urinary tract infections
Adult: Available preparation:
Sulfamethoxazole 400 mg and trimethoprim 80 mg in 5 mL solution for infusion

For cases where there is bacteriological evidence of susceptibility and a good reason to prefer the combination instead of a single antibiotic: In patients unable to take oral treatment: 960 mg 12 hourly via infusion over 60-90 minutes. Severe infections: 2,880 mg daily in 2 divided doses. Continue until the patient is symptom-free for 2 days; most patients require treatment for at least 5 days. Consideration must be given to local treatment guidelines on the appropriate use of antibacterials. Dosage recommendation may vary among individual products or between countries (refer to detailed product guideline).

Intravenous
Pneumocystis (carinii) jirovecii pneumonia
Adult: Available preparation:
Sulfamethoxazole 400 mg and trimethoprim 80 mg in 5 mL solution for infusion

Treatment in patients unable to take oral treatment: 120 mg/kg daily in 2-4 divided doses via infusion over 60-90 minutes. Shift to oral therapy as soon as possible then continue for a total treatment period of 14 days. Consideration must be given to local treatment guidelines on the appropriate use of antibacterials. Dosage recommendation may vary among individual products or between countries (refer to detailed product guideline).

Oral
Acute exacerbations of chronic bronchitis, Acute uncomplicated urinary tract infections
Adult: Available preparations:
Sulfamethoxazole 400 mg and trimethoprim 80 mg tab
Sulfamethoxazole 800 mg and trimethoprim 160 mg tab
Sulfamethoxazole 400 mg and trimethoprim 80 mg per 5 mL oral susp

For cases where there is bacteriological evidence of susceptibility and a good reason to prefer the combination instead of a single antibiotic: 960 mg bid. Severe infections: 2,880 mg daily in 2 divided doses. Continue until the patient is symptom-free for 2 days; most patients require treatment for at least 5 days. Reassess patient if there is no clinical improvement after 7 days. Alternatively for acute uncomplicated lower UTI, short-term treatment duration of 1-3 days has shown to be effective. Consideration must be given to local treatment guidelines on the appropriate use of antibacterials. Dosage recommendation may vary among individual products or between countries (refer to detailed product guideline).
Child: Available preparations:
Sulfamethoxazole 400 mg and trimethoprim 80 mg tab
Sulfamethoxazole 800 mg and trimethoprim 160 mg tab
Sulfamethoxazole 200 mg and trimethoprim 40 mg per 5 mL oral susp
Sulfamethoxazole 400 mg and trimethoprim 80 mg per 5 mL oral susp

As 200 mg/40 mg per 5 mL susp: 6 weeks to 5 months 120 mg bid; 6 months to 5 years 240 mg bid; 6-12 years 480 mg bid. As tab or 400 mg/80 mg per 5 mL susp: >12 years Same as adult dose. Standard dose for children is equivalent to approx 30 mg sulfamethoxazole and 6 mg trimethoprim per kg daily in 2 divided doses. Continue until the patient is symptom-free for 2 days; most patients require treatment for at least 5 days. Reassess patient if there is no clinical improvement after 7 days. Consideration must be given to local treatment guidelines on the appropriate use of antibacterials. Dosage recommendation may vary among individual products or between countries (refer to detailed product guideline).

Oral
Pneumocystis (carinii) jirovecii pneumonia
Adult: Available preparations:
Sulfamethoxazole 400 mg and trimethoprim 80 mg tab
Sulfamethoxazole 800 mg and trimethoprim 160 mg tab
Sulfamethoxazole 400 mg and trimethoprim 80 mg per 5 mL oral susp

Treatment: Up to 120 mg/kg daily in 2-4 divided doses for 14-21 days. Consideration must be given to local treatment guidelines on the appropriate use of antibacterials. Dosage recommendation may vary among individual products or between countries (refer to detailed product guideline).
Child: Available preparations:
Sulfamethoxazole 400 mg and trimethoprim 80 mg tab
Sulfamethoxazole 800 mg and trimethoprim 160 mg tab
Sulfamethoxazole 200 mg and trimethoprim 40 mg per 5 mL oral susp
Sulfamethoxazole 400 mg and trimethoprim 80 mg per 5 mL oral susp

>12 years Same as adult dose.

Oral
Prophylaxis of Pneumocystis (carinii) jirovecii pneumonia
Adult: Available preparations:
Sulfamethoxazole 400 mg and trimethoprim 80 mg tab
Sulfamethoxazole 800 mg and trimethoprim 160 mg tab
Sulfamethoxazole 400 mg and trimethoprim 80 mg per 5 mL oral susp

960 mg once daily for 7 days, or 960 mg once daily 3 times a week on alternate days, or 960 mg bid 3 times a week on alternate days. Consideration must be given to local treatment guidelines on the appropriate use of antibacterials. Dosage recommendation may vary among individual products or between countries (refer to detailed product guideline).
Child: Available preparations:
Sulfamethoxazole 400 mg and trimethoprim 80 mg tab
Sulfamethoxazole 800 mg and trimethoprim 160 mg tab
Sulfamethoxazole 200 mg and trimethoprim 40 mg per 5 mL oral susp
Sulfamethoxazole 400 mg and trimethoprim 80 mg per 5 mL oral susp

As 200 mg/40 mg per 5 mL susp: 6 weeks to 5 months 120 mg bid for 7 days, or 120 mg bid 3 times a week on alternate days, or 120 mg bid 3 times a week on consecutive days, or 240 mg once daily 3 times a week on consecutive days; 6 months to 5 years 240 mg bid for 7 days, or 240 mg bid 3 times a week on alternate days, or 240 mg bid 3 times a week on consecutive days, or 480 mg once daily 3 times a week on consecutive days; 6-12 years 480 mg bid for 7 days, or 480 mg bid 3 times a week on alternate days, or 480 mg bid 3 times a week on consecutive days, or 960 mg once daily 3 times a week on consecutive days. As tab or 400 mg/80 mg per 5 mL susp: >12 years 960 mg bid for 7 days, or 960 mg bid 3 times a week on alternate days, or 960 mg bid 3 times a week on consecutive days, or 1,920 mg once daily 3 times a week on consecutive days. The daily dose given on treatment day is approx 750 mg sulfamethoxazole/m2/day and 150 mg trimethoprim/m2/day. Max: 1,920 mg daily. Consideration must be given to local treatment guidelines on the appropriate use of antibacterials. Dosage recommendation may vary among individual products or between countries (refer to detailed product guideline).

Oral
Acute otitis media
Child: Available preparations:
Sulfamethoxazole 400 mg and trimethoprim 80 mg tab
Sulfamethoxazole 800 mg and trimethoprim 160 mg tab
Sulfamethoxazole 200 mg and trimethoprim 40 mg per 5 mL oral susp
Sulfamethoxazole 400 mg and trimethoprim 80 mg per 5 mL oral susp

As 200 mg/40 mg per 5 mL susp: 6 weeks to 5 months 120 mg bid; 6 months to 5 years 240 mg bid; 6-12 years 480 mg bid. As tab or 400 mg/80 mg per 5 mL susp: >12 years Same as adult dose. Standard dose for children is equivalent to approx 30 mg sulfamethoxazole and 6 mg trimethoprim per kg daily in 2 divided doses. Continue until the patient is symptom-free for 2 days; most patients require treatment for at least 5 days. Reassess patient if there is no clinical improvement after 7 days. Consideration must be given to local treatment guidelines on the appropriate use of antibacterials. Dosage recommendation may vary among individual products or between countries (refer to detailed product guideline).
Renal Impairment
Oral
CrCl (mL/min) Dosage
<15 Adults and children >12 years: Not recommended.
15-30 Adults and children >12 years: Half the standard dose.

IV
CrCl (mL/min) Dosage
<15 Not recommended.
15-30 Half the standard dose.
Hepatic Impairment
Severe: Contraindicated.
Administration
Should be taken with food.
Reconstitution
IV infusion: Dilute each 5 mL (480 mg/5 mL) of concentrate usually in 125 mL of dextrose 5% in water prior to administration. In patients with fluid restriction, each 5 mL of the concentrate may be diluted in 75 mL of dextrose 5% in water.
Contraindications
Hypersensitivity to sulfonamides or trimethoprim. History of drug-induced immune thrombocytopenia with sulfonamides or trimethoprim use; acute porphyria, megaloblastic anaemia due to folate deficiency. Severe hepatic parenchymal damage; severe renal insufficiency where repeated plasma concentration measurements cannot be performed. Infants <6 weeks, except for the treatment/prophylaxis of Pneuomocsytis jirovecii pneumonia in infants ≥4 weeks. Concurrent administration with dofetilide (IV).
Special Precautions
Patient with severe allergy or atopy, bronchial asthma, thyroid dysfunction, G6PD deficiency, potential folate deficiency (e.g. malnourished, receiving chronic anticonvulsant therapy), predisposition to hyperkalaemia, AIDS; serious haematologic disorder. When used for uncomplicated UTIs, avoid using the combination if a single antibacterial agent is effective. Do not use for the treatment of group A β-haemolytic streptococcal infections. Avoid use with leucovorin in the treatment of HIV patients with P. jirovecii pneumonia. Slow acetylators. Renal and mild to moderate hepatic impairment. Children and elderly. Pregnancy and lactation.
Adverse Reactions
Significant: Hyperkalaemia, hyponatraemia, hypoglycaemia, sulfonamide allergy, porphyria exacerbation; haemolysis (in G6PD deficient patient). Rarely, crystalluria.
Gastrointestinal disorders: Nausea, diarrhoea, vomiting.
General disorders and administration site conditions: Local infusion-site reaction (e.g. pain, irritation, inflammation).
Infections and infestations: Fungal overgrowth.
Metabolism and nutrition disorders: Anorexia.
Nervous system disorders: Headache, drowsiness.
Skin and subcutaneous tissue disorders: Rashes.
Potentially Fatal: Stevens-Johnson syndrome, toxic epidermal necrolysis, blood dyscrasias (e.g. agranulocytosis, aplastic anaemia), immune-mediated thrombocytopenia, cholestatic jaundice, fulminant hepatic necrosis, hypersensitivity of the respiratory tract; Clostridium difficile-associated diarrhoea, pseudomembranous colitis.
IV/Parenteral/PO: D
Monitoring Parameters
Perform culture and susceptibility tests; consult local institutional recommendations before treatment initiation due to antibiotic resistance risks. Obtain LFTs and renal function tests before initiating treatment. Monitor CBC with differential, serum K and Na, creatinine, and BUN periodically on prolonged therapy; urinalysis with microscopic exam. Closely check for signs and symptoms of skin reactions.
Overdosage
Symptoms: Nausea, vomiting, dizziness, confusion, and bone marrow depression. Management: Supportive and symptomatic treatment. Empty stomach immediately by inducing emesis or by performing gastric lavage. Fluids may be given if urine output is low based on the renal function status. Ca folinate (5-10 mg/day) may be given to counteract any folate deficiency effects of trimethoprim on the bone marrow.
Drug Interactions
Increased risk of thrombocytopenia with or without purpura with thiazide diuretics in the elderly. May potentiate the effects of oral anticoagulants (e.g. warfarin) and phenytoin. May increase risk of nephrotoxicity with ciclosporin. May elevate the plasma levels and risk of megaloblastic anaemia of methotrexate.
Sulfamethoxazole: May potentiate the effects of sulfonylureas.
Trimethoprim: May increase serum concentrations of digoxin, procainamide, repaglinide, zidovudine, zalcitabine, and lamivudine. May decrease serum concentrations with rifampicin. May increase risks of megaloblastic anaemia with other folate inhibitors (e.g. pyrimethamine). May enhance the risk of hyperkalaemia with ACE inhibitors.
Potentially Fatal: Increased plasma levels of dofetilide which causes ventricular arrhythmia associated with QT prolongation, including torsades de pointes. Concomitant use with leucovorin may cause treatment failure when used in the treatment of HIV patients with P. jirovecii pneumonia.
Lab Interference
Trimethoprim: May interfere with serum or plasma creatinine estimation using Jaffé alkaline picrate reaction assay. May increase serum methotrexate with dihydrofolate reductase method.
Action
Description: Sulfamethoxazole and trimethoprim is an antibacterial combination that blocks 2 consecutive steps in the biosynthesis of purines and nucleic acids essential to bacteria.
Sulfamethoxazole, an intermediate-acting sulfonamide, interferes with the bacterial folic acid synthesis and growth by competitive inhibition of dihydrofolic acid formation from para-aminobenzoic acid.
Trimethoprim, a diaminopyrimidine, inhibits dihydrofolic acid reduction to tetrahydrofolate leading to the sequential inhibition of enzymes of the folic acid pathway.
Synonym: co-trimoxazole.
Pharmacokinetics:
Absorption: Rapidly and almost completely (90-100%) absorbed from the gastrointestinal tract. Time to peak plasma concentration: 1-4 hours (oral); approx 1 hour (IV).
Distribution: Widely distributed into body tissues and fluids, including sputum, middle ear fluid, vaginal fluid, bile, CSF and aqueous humour. Crosses the placenta and enters breast milk.
Sulfamethoxazole: Distributed also in the pleural and other effusions. Plasma protein binding: Approx 70%.
Trimethoprim: Distributed also into bronchial secretions, lungs, kidneys, prostatic tissue and fluid. Plasma protein binding: Approx 44%.
Metabolism: Sulfamethoxazole: Metabolised in the liver via oxidation into hydroxylamine, acetylation to the inactive N4-acetyl derivative, and glucuronidation.
Trimethoprim: Metabolised in the liver (approx 10-20%) into oxide and hydroxy derivatives.
Excretion: Sulfamethoxazole: Via urine (approx 80-100%; approx 60% as acetyl derivative, with the remainder as unchanged drug and glucuronide). Elimination half-life: 9-12 hours.
Trimethoprim: Via urine (approx 40-60% mainly as unchanged drug). Elimination half-life: 6-11 hours.
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.
ATC Classification
J01EE01 - sulfamethoxazole and trimethoprim ; Belongs to the class of combinations of sulfonamides and trimethoprim, including derivatives. Used in the systemic treatment of infections.
References
Anon. Co-trimoxazole. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 05/08/2020.

Anon. G6PD - Sulfamethoxazole (Pharmacogenomics). Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 05/08/2020.

Anon. Sulfamethoxazole and Trimethoprim. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 05/08/2020.

Bactrim DS and Bactrim Tablet (Sun Pharmaceutical Industries, Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 05/08/2020.

Buckingham R (ed). Co-trimoxazole. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 05/08/2020.

Buckingham R (ed). Sulfamethoxazole. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 05/08/2020.

Buckingham R (ed). Trimethoprim. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 05/08/2020.

Co-Trimoxazole 16 mg/80 mg per mL for Infusion (Aspen Pharma Trading Limited). MHRA. https://products.mhra.gov.uk. Accessed 05/08/2020.

Co-Trimoxazole 40 mg/200 mg per 5 mL Paediatric Suspension (Aspen Pharma Trading Limited). MHRA. https://products.mhra.gov.uk. Accessed 17/02/2021.

Co-Trimoxazole 80 mg/400 mg per 5 mL Adult Suspension (Aspen Pharma Trading Limited). MHRA. https://products.mhra.gov.uk. Accessed 05/08/2020.

Co-Trimoxazole 800 mg/160 mg Forte Tablets (Aspen Pharma Trading Limited). MHRA. https://products.mhra.gov.uk. Accessed 17/02/2021.

Comazole Tablet and Suspension (SM Pharmaceuticals Sdn Bhd). MIMS Malaysia. http://www.mims.com/malaysia. Accessed 17/02/2021.

Fectrim 80/400 mg Tablets (Hualan Pharmaceuticals Limited). MHRA. https://products.mhra.gov.uk. Accessed 05/08/2020.

Joint Formulary Committee. Co-trimoxazole. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 05/08/2020.

Sulfamethoxazole and Trimethoprim Injection (Mylan Institutional LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 05/08/2020.

Sulfatrim Suspension (Pharmaceutical Associates, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 05/08/2020.

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 © 2021 MIMS. All rights reserved. Powered by MIMS.com
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