Drug interactions

Question 1

Why are interactions particularly important for narrow therapeutic range drugs?

Answer 1

because small changes in their concentration can cause severe toxicity

Question 2

Narrow therapeutic range drugs mnemomic

Answer 2

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G- Gentamicin
W- Warfarin
L- Lithium
D- Digoxin
T- Theophylline
M-Methotrexate
P- Phenytoin
I- Insulin
C- Ciclosporin

Question 3

Name of drugs that are metabolised by the p450 system that are affected by cytochrome p450 inducers and inhibitors

Answer 3

COWPATS

C- Ciclosporin, Carbamazepine, Citalopram
O- Oral contraceptive pills
W- Warfarin
P- Phenytoin, Protease inhibitors
A- Acetylcholinesterase inhibitors (donepezil)
T- Theophylline
S- Statins , Steroids

Question 4

Cytochrome P450 inhibitors mnemonic

Answer 4

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S- Sodium Valproate
C- Ciprofloxacin
S- Sulphonamides
C-Cimetidine
A- Antifungals, Amiodarone
I- Isoniazid
E- Erythromycin, Clarithromycin, Azithromycin
G- Grapefruit juice

Question 5

Cytochrome P450 inducers mnemonic

Answer 5

CRAPS out the drugs

C- Carbamazepine
R- Rifampicin
A- bArbiturates
P- Phenytoin
S- St John’s Wort