<!-- Definition and medical uses -->

Trimethoprim/sulfamethoxazole, sold under the trade names Bactrim, Cotrim (a short form of the British Approved Name, Co-trimoxazole) and Septra, among others, is a fixed-dose combination antibiotic medication used to treat a variety of bacterial infections. It consists of one part trimethoprim to five parts sulfamethoxazole. It is available as a generic medication.

Medical uses

Trimethoprim/sulfamethoxazole generally kills bacteria, by blocking the microorganisms' ability to make and to use folate. People who get Pneumocystis pneumonia have a medical condition that weakens their immune system, like HIV/AIDS, or take medicines (such as corticosteroid, monoclonal antibody and immunosuppressants) that reduce the body's ability to fight bacterial and viral infections. People with HIV/AIDS are less likely to get Pneumocystis pneumonia as a result of antiretroviral therapy (ART). However, Pneumocystis pneumonia is still a substantial public health problem. Most of what is scientifically known about Pneumocystis pneumonia and its treatment comes from studying people with HIV/AIDS.

Pregnancy and breast feeding

Its use during pregnancy is contraindicated, although it has been placed in Australian pregnancy category C. Animal studies have yielded similarly discouraging results.

Infants

Its use in those less than 2 months of age is not recommended due to the risk of adverse side effects.

Adverse effects

Common side effects include nausea, vomiting, rash, and diarrhea.

Contraindications

Contraindications include the following:

  • ACE inhibitors like captopril, enalapril, lisinopril, perindopril, and ramipril due to the potential for additive hyperkalaemic effects
  • Potassium aminobenzoate — effects of sulfonamides (like Sulfamethoxazole) inhibited.
  • Laboratory tests — trimethoprim and sulfonamides have been reported to interfere with diagnostic tests, including serum-methotrexate and elevated serum creatinine levels, also urea, urinary glucose and urobilinogen tests.

Overdose

Likely signs of toxicity include: Trimethoprim and sulfamethoxazole have a greater effect when given together than when given separately, because they inhibit successive steps in the folate synthesis pathway. They are given in a one-to-five ratio in their tablet formulations so that when they enter the body their concentration in the blood and tissues is roughly one-to-twenty — the exact ratio required for a peak synergistic effect between the two. during bacterial replication.

The effects of trimethoprim causes a backlog of dihydrofolate (DHF) and this backlog can work against the inhibitory effect the drug has on tetrahydrofolate biosynthesis. This is where the sulfamethoxazole comes in; its role is in depleting the excess DHF by preventing it from being synthesised in the first place.

{| class = wikitable

|+ Pharmacokinetics of co-trimoxazole

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| Otitis media || || || || Clinical trials have confirmed its efficacy in chronic active and acute otitis media.

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| Travelers' diarrhea, treatment & prophylaxis || || || || Clinical trials have confirmed its efficacy as a treatment for travellers' diarrhea.

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| Urinary tract infection || || || || Clinical trials have confirmed its efficacy in this indication.

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| colspan="5" align="center" | <big>Bacterial infections</big>

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| Acne vulgaris || || || || At least one clinical trial supports its use in this indication.

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| Listeria || || || || Well-designed clinical trials are lacking.

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| Melioidosis || || || || Clinical trials have confirmed its efficacy, with or without adjunctive doxycycline; although, co-trimoxazole alone seems preferable.

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| Pertussis (whooping cough) || || || || One Cochrane review supports its efficacy in preventing the spread of pertussis.

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| Shigellosis || || || || Generally accepted treatment for shigellosis. A Cochrane review found that while it is an effective treatment for shigellosis it also produces more significant adverse effects than other antibiotic drugs.

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| Staphylococcus aureus infections || || || || In vitro and in vivo activity against both non-resistant and methicillin-resistant Staphylococcus aureus (MRSA) infections.

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| Tuberculosis || || || || In vitro and in vivo activity against both nonresistant and MDR strains of TB.

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| Whipple's disease || || || || Co-trimoxazole is the recommended standard treatment for whipple's disease in some treatment protocols.

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| colspan="5" align="center" | <big>Fungal and protozoal infections</big>

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| Isosporiasis || || || || Clinical trials have confirmed its use in this indication.

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| Malaria || || || || Clinical trials have confirmed its efficacy in both the treatment and prevention of malaria.

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| Pneumocystis jirovecii pneumonia || || || || Its use as a prophylactic treatment is supported by one clinical trial involving children with acute lymphoblastic leukaemia. Other than this and one other clinical trial into its efficacy as a treatment for pneumocystis pneumonia, data on its use in both the treatment and prevention of pneumocystis pneumonia is significantly lacking.

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| Toxoplasmosis || || || || Clinical trials have confirmed its prophylactic and therapeutic utility in cases of toxoplasmosis.

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Brand names

Trimethoprim/sulfamethoxazole may be abbreviated as SXT, SMZ-TMP, TMP-SMX, TMP-SMZ, or TMP-sulfa. The generic British Approved Name (BAN) Co-trimoxazole is used for trimethoprim/sulfamethoxazole manufactured and sold by many different companies.

The following list of brand names is incomplete:

  • Bactrim, Bactrimel (manufactured by Roche and distributed in Europe)
  • Bactrom (Venezuela)
  • Bibactin (manufactured by PPM and distributed in Cambodia and some African countries)
  • Biseptol
  • Sumetrolim
  • Co-trimoxazole (used as generic UK name)
  • Cotrim
  • Deprim (AFT Pharmaceuticals)
  • Diseptyl (Israel)
  • Graprima Forte Kaplet (manufactured by PT Graha Farma and distributed in Indonesia)
  • Infectrin, Bactrim (Brazil)
  • Novo-Trimel
  • Primadex (manufactured by Dexa Medica and distributed in Indonesia)
  • Primotren (Lek in Slovenia and other countries)
  • Resprim
  • Sanprima (manufactured by Sanbe Farma and distributed in Indonesia)
  • Septra (Aspen Pharmacare and formerly GlaxoSmithKline)
  • Septram (Panama)
  • Septran (GlaxoSmithKline)
  • Septrin (Spain)
  • Sulfatrim
  • Teva-Trimel
  • Trisul
  • Vactrim (manufactured and distributed in Laos)

Economics

Trimethoprim/sulfamethoxazole is relatively inexpensive as of 2019.

References