Trimethoprim

Question 1

What is the method of action of trimethoprim?

Answer 1

Binds to and reversibly inhibits bacterial dihydrofolate reductase (DHFR) enzyme, blocking the production of tetrahydrofolate.

Question 2

Which organisms is trimethoprim active against?

Answer 2

A wide range of gram-positive and -negative organisms. Enterobacteria, E. coli, K. pneumoniae, S. pneumoniae, H. influenzae, S. aureus.

Question 3

What are some of the indications of trimethoprim?

Answer 3

Pneumonia, RTIs, shigellosis, invasive salmonella, UTIs, resistant acne, prostatitis.

Question 4

What are some of the side effects of trimethoprim?

Answer 4

Allergic reactions, anaphylaxis, photosensitivity, aseptic meningitis, GI disturbances.

Question 5

What are the contraindications to the use of trimethoprim?

Answer 5

Blood dyscrasias - bruising, bleeding, sore throats, fever, rash, malaise.

Question 6

What monitoring should be carried out when a patient is on trimethoprim?

Answer 6

Blood counts when on long term therapy.

Question 7

What important counselling point shoiuld be given to patients and carers when a patient is on long term trimethoprim therapy?

Answer 7

The sings of blood disorders one shoulkd be aware of.

Question 8

Which combination drug can trimethoprim be found in, commonly used prophylactically in HIV patients?

Answer 8

Co-trimoxazole.

Question 9

What is one of the most serious side effects associated with co-trimoxazole use?

Answer 9

Stephen Johnson Syndrome.