Cytochrome Enzymes

Question 1

What are some CYP P450 inducers?

Answer 1

Rifampicin
Carbamazepine
Phenytoin
Omeprazole

Question 2

What are some CYP P450 inhibitors?

Answer 2

Ciprofoixacin
Anti-fungals
Fluoxetine 
Paroxetine 
HIV anti-virals eg indinavir

Question 3

Give some examples of P450 enzymes

Answer 3

CYP 3A4
CYP 2D6
CYP 2C9

Question 4

What are some substrates of CYP 3A4?

Answer 4

Calcium channel blockers 
Macrolides
Anti-retroviral drugs 
Statins 
COCP, POP

Question 5

What are some inhibitors of CYP 3A4?

Answer 5

Grapefruit

Protease inhibitors - ritonavir

Question 6

What are some inducers of CYP 3A4?

Answer 6

Carbamazepine
Phenytoin
Rifampicin
St John’s Wort

Question 7

What are some substrates for CYP 2D6?

Answer 7

Tricyclics antidepressants
Antipsychotics
β-blockers

Question 8

What are some inhibitors of CYP 2D6?

Answer 8

SSRIs

Some anti-arrhythmics

Question 9

What are some substrates for CYP 2C9?

Answer 9

Warfarin
NSAIDs
Sulfonylurea

Question 10

What are some inhibitors of CYP 2C9?

Answer 10

Amiodarone
Clopidogrel
Quinolone
Metronidazole

Question 11

What are some inducers of CYP 2C9?

Answer 11

Barbiturates
Phenytoin
Rifampicin
St John’s Wort

Question 12

What is the effect of CYP P450 inhibitors?

Answer 12

Prevent metabolism of certain drugs
Therefore increase therapeutic effect

For example, drinking grapefruit juice while taking statins => increased reduction in plasma LDL. However also increases risk of side effects eg rhabdomyolysis

Question 13

What is the effect of CYP P450 inducers?

Answer 13

Increase metabolism of certain drugs
Therefore decrease therapeutic benefit

For examples, taking St John Wort’s with COCP/POP => less effective => inc risk of pregnancy