Trimethoprim Flashcards
What is trimethoprim used for?
Trimethoprim is used as a first line treatment for UTIs.
What is Co-trimoxazole and what is it used for?
Co-trimoxazole is trimethoprim + sulfamethoxazole . It is used to treat pneumocystitis pneumonia in immune-suppressed pt.
How does trimethoprim work?
Trimethoprim inhibits bacterial folate synthesis. so bacteria cant make DNA. This slows their growth.
What bacteria does trimethoprim work against?
Gram positive, gram negative bacteria
enterobacteria e.g. E.coli
HOWEVER WIDESPREAD RESISTANCE so usage is limited
What are the side effects of trimethoprim/
- GI upset (nausea, vomiting, sore mouth)
- Skin rash
- anaphylaxis (rare)
- haematological disorders e.g. megaloblastic anaemia, leucopenia, thrombocytopenia
- hyperkalaemia
- elevated plasma creatinine concentration
Why is trimethoprim contraindicated in the 1st trimester of pregnancy?
trimethoprim is a folate antagonist so is associated with increased risk of fetal abnormalities
What groups of patients are particularly susceptible to adverse affects with trimethoprim?
- neonates
- elderly
- HIV infection
What are the interactions of trimethoprim?
- potassium elevating drugs ( e.g. aldosterone antagonist, ACEi, angiotensin receptor blocker)
- use with folate antagonists e.g. methotrexate
- drugs that increase folate metabolism e.g.phenytoin
- warfarin