trimethoprim

Question 1

trimethoprim is contraindicated in (1)

Answer 1

blood dyscrasias

Question 2

trimethoprim interaction with vit K antagonists

Answer 2

increases AC effect of acenocoumarol, warfarin, pheninidione

Question 3

trimethoprim interacts with this high risk antipsychotic

hint - blood

Answer 3

clozapine
trimethoprim may increase risk of neutropenia
avoid!

Question 4

azathioprine, mercaptopurine interaction

Answer 4

can increase risk of haemtological toxicity when given with azathioprine in renal transplant pt

Question 5

MTX interaction

Answer 5

increased risk of haematological SE, some times fatal
avoid
(both are anti folate)
also increased risk nephrotoxicity

Question 6

what electrolyte disturbance can it cause

Answer 6

hyperkalaemia

caution with other drugs e.g. ACE or ARB or SEAT

Question 7

trimethoprim is …toxic

Answer 7

nephro
so increased risk of nephrotoxicity with others e.g. cephalosporins, ACE, ARB, Cs, NSAIDs

Question 8

Interaction with NSAIDS (2)

Answer 8

hyperkalaemia
nephrotoxicity

Question 9

interaction with lithium

Answer 9

not severe. no class. nephrotoxicity

Question 10

true or false - it can cause fungal overgrowth as a SE

Answer 10

true

Question 11

common SE

Answer 11

electrolyte imbalance (hyperK)
fungal overgrowth
diarrhoea
nausea, vomiting
headache
skin reactions

Question 12

use in pregnancy

Answer 12

avoid.
teratogenic risk in 1st trimester

Question 13

use in renal impairment if eGFR less than 15

Answer 13

reduce to half normal dose

Question 14

use in RI if eGFR 15-30

Answer 14

half normal dose after 3 days

Question 15

monitoring requirements

Answer 15

blood counts with long term use and in pt with, or at risk of, folate deficiency

serum electrolytes in pt at risk of developing hyperkalaemia, and consider monitoring in other pt, esp with long term use

consider monitoring renal function, esp long term use

plasma-trimethoprim conc may be considered with long term use and specialist advice

Question 16

if pt are on long term treatment, they should be told how to recognise ….

Answer 16

signs of blood disorders
seek immediate medical attention if symptoms such as fever, sore throat, rash, mouth ulcers, purpura, bruising or bleeding develop

Question 17

can it be used for RTI

Answer 17

yes

Question 18

dose in prophylaxis of recurrent UTI in adults

(hint 2 options, one is prn)

Answer 18

100mg OD to be taken at night

alternatively 200mg for one dose, take following exposure to trigger

Question 19

dose in prophylaxis of recurrent UTI in pt with eGFR under 15

Answer 19

half normal dose..
so 50mg OD to be taken at night

Question 20

dose for UTI catheter associated

Answer 20

200mg BD 7 days
14 days if upper UTI symptoms present

Question 21

dose for lower UTI

Answer 21

200mg BD for 3 days
7 days in males