PSA Chapter 1: Basic Principles of Prescribing

Question 1

CYP450 enzyme inducers

Answer 1

PC BRAS
Phenytoin
Carbamazepine
Barbiturates
Rifampicin
Alcohol (chronic excess)
Sulphonylureas

(Inducers: increase enzyme activity –> increase metabolism of drug –> reduce drug concentration)

Question 2

CYP450 enzyme inhibitors

Answer 2

AO-DEVICES
Allopurinol
Omeprazole
Disulfiram
Ethanol (acute excess)
Valproate
Isoniazid
Ciprofloxacin
Erythromycin
Sulphonamides

Question 3

Drugs to stop before surgery

Answer 3

I LACK WOP

Insulin (start on IV variable rate insulin infusion + 5% dextrose)

Lithium (stop day before)

Anticoagulants/antiplatelets (clopidogrel stopped 7 days before, others may continue due to minimal risk of bleeding)

COCP/HRT (stopped 4w before)

K-sparing diuretics/diuretics (stop day of)

Warfarin (stop 5 days before)

Oral hypoglycaemics (metformin stop day of, others stop 24h before)

Perindopril (ie ACEi, stop day of)