Trimethoprim

Trimethoprim
ATC Code J01EA01
Formula C14H18N4O3
Molar Mass (g·mol−1) 290,32
Physical State solid
Melting Point (°C) 199–203
PKS Value 7,12
CAS Number 738-70-5
PUB Number 5578
Drugbank ID DB00440
Solubility low in water

Basics

Trimethoprim (TMP) is an antibiotic that is mainly used to treat bladder infections. Other uses include middle ear infections and traveler's diarrhea. In combination with sulfamethoxazole or dapsone, it can be used for pneumocystis pneumonia in people with HIV/AIDS. It is taken by mouth. Trimethoprim is on the WHO essential medicines list and requires a prescription.

Pharmacology

Pharmacodynamics

Trimethoprim binds to dihydrofolate reductase and inhibits the reduction of dihydrofolic acid (DHF) to tetrahydrofolic acid (THF). THF is an essential building block for DNA synthesis. The affinity of trimethoprim for bacterial dihydrofolate reductase is several thousand times greater than its affinity for human dihydrofolate reductase. Thus, the effects on human DNA synthesis are comparatively small.

Pharmacokinetics

Maximum plasma concentration is usually reached at 1-4 hours after ingestion. Approximately 44% of the drug is present bound to plasma proteins. The metabolism of trimethoprim is mainly catalyzed by the enzymes CYP2C9 and CYP3A4. Excretion is largely via the urine.

Toxicity

Side effects

Common side effects:

  • Nausea
  • Taste changes
  • Vomiting
  • Diarrhea
  • Rash
  • UV sensitivity
  • Itch

Rare side effects

  • thrombocytopenia (low platelet count)
  • megaloblastic anemia
  • increased potassium levels (hyperkalemia)
  • increase in serum creatinine
  • use in EHEC infections may lead to increased expression of Shiga toxin

Toxicological data

LD50 (mouse, oral) 2764 mg-kg-1

Sources

  • Drugbank
  • PubChem
  • Aktories, Förstermann, Hofmann, Starke: Allgemeine und spezielle Pharmakologie und Toxikologie, Elsvier, 2017
Markus Falkenstätter

Markus Falkenstätter
Author

Markus Falkenstätter ist Autor zu pharmazeutischen Themen in der Medizin-Redaktion von Medikamio. Er befindet sich im letzten Semester seines Pharmaziestudiums an der Universität Wien und liebt das wissenschaftliche Arbeiten im Bereich der Naturwissenschaften.

Mag. pharm Stefanie Lehenauer

Mag. pharm Stefanie Lehenauer
Lector

Stefanie Lehenauer ist seit 2020 freie Autorin bei Medikamio und studierte Pharmazie an der Universität Wien. Sie arbeitet als Apothekerin in Wien und ihre Leidenschaft sind pflanzliche Arzneimittel und deren Wirkung.

Your personal medicine assistent

afgis-Qualitätslogo mit Ablauf Jahr/Monat: Mit einem Klick auf das Logo öffnet sich ein neues Bildschirmfenster mit Informationen über Medikamio GmbH & Co KG und sein/ihr Internet-Angebot: medikamio.com/ This website is certified by Health On the Net Foundation. Click to verify.
Drugs

Search our database for drugs, sorted from A-Z with their effects and ingredients.

Substances

All substances with their common uses, chemical components and medical products which contain them.

Diseases

Causes, symptoms and treatment for the most common diseases and injuries.

The contents shown do not replace the original package insert of the medicinal product, especially with regard to dosage and effect of the individual products. We cannot assume any liability for the correctness of the data, as the data was partly converted automatically. A doctor should always be consulted for diagnoses and other health questions. Further information on this topic can be found here.