Sulfonamides

Question 1

Nitrofurantoin and pregnancy

Answer 1

Avoid at term

Question 2

Trimethoprim and pregnancy

Answer 2

Avoid in first trimester

Question 3

CI of nitrofurantoin

Answer 3

<3 months

Question 4

Usual dose of nitrofurantoin UTI

Answer 4

3 days women, 7 days men
IR - 50mg QDS
MR - 100mg BD

Question 5

Key side effects of nitrofurantoin

Answer 5

Urine discolouration (yellow-brown)
hepatic disorders
GI upset

Question 6

Counselling nitrofurantoin

Answer 6

Best taken with or just after food

Question 7

Monitoring long term use nitrofurantoin

Answer 7

Liver function and pulmonary Sx

Question 8

Trimethoprim UTI doses prophylaxis and tx

Answer 8

UTI TX - 200mg BD
UTI prophylaxis 100mg ON

Duration
3 days female uncomplicated
7 days pregnant females, males and catheter associated

Question 9

Side effects of trimethoprim

Answer 9

Blood disorders - agranulocytosis, megaloblastic anaemia, leucopenia
Skin rashes, diarrhoea, N+V
HYPERkalaemia
HYPOnatraemia

Question 10

Interactions of trimethoprim

Answer 10

Methotrexate - Increase ADR risk, increased risk of bone marrow suppression
Warfarin - Increased anticoagulant effect
Phenytoin - Increased levels of phenytoin
Hyperkalaemia risk - ACEi, ciclosporin, K+sparing diuretics

Question 11

Renal impairment trimethoprim

Answer 11

eGFR <15ml/min half normal dose

eGFT 15-30ml/min after 3 days, half normal dose

Question 12

Co-trimoxazole composed of?

Answer 12

Trimethoprim + sulfamethoxazole

Question 13

Monitoring co-trimoxazole

Answer 13

Blood disorders - agranulocytosis, megaloblastic anaemia, leucopenia
Skin rashes, diarrhoea, N+V
HYPERkalaemia
HYPOnatraemia

AND SJS and TEN (toxic epidermal necrolysis)

Question 14

Co-trimoxazole pregnancy

Answer 14

Teratogenic risk in first trimester (trimethoprim a folate antagonist).

Neonatal haemolysis and methaemoglobinaemia in third trimester; fear of increased risk of kernicterus in neonates appears to be unfounded.