Drug metabolism

Question 1

x

Answer 1

x

Question 2

CYP450 inhibitors

Answer 2

Use the mnemonic: MAGIC RACKS in GQ
Macrolides (erythromycin) is a P450 inhibitor.
Amiodarone is a P450 inhibitor.
Grapefruit juice is a P450 inhibitor.
Isoniazid is a P450 inhibitor.
Ciprofloxacin is a P450 inhibitor.
Ritonavir is a P450 inhibitor.
Acute alcohol intoxication is a P450 inhibitor.
Cimetidine is a P450 inhibitor.
Ketoconazole is a P450 inhibitor.
Sulfonamides are P450 inhibitors.
Gemfibrozil is a P450 inhibitor.
Quinidine is a P450 inhibitor.

Question 3

CYP450 inducers

Answer 3

Use the mnemonic: Momma Barb Steals Phen-phen and Refuses Greasy Carbs Chronically

Modafinil is a P450 inducer.
Barbiturates are P450 inducers.
St. John’s wort is a P450 inducer.
Phenytoin is a P450 inducer.
Rifampin is a P450 inducer.
Griseofulvin is a P450 inducer.
Carbamazepine is a P450 inducer.
Chronic ethanol use/abuse is a P450 inducer.
Note: Smoking (aromatic hydrocarbons) is also a P450 inducer.

Question 4

What are three main reactions that drugs undergo during Phase I metabolism?

Answer 4

Oxidation, Reduction, Hydrolysis

Question 5

What is the main purpose of a Phase I reaction?

Answer 5

Make the drug more water soluble, usually less active form of drug.

Question 6

What happens during a phase II reaction?

Answer 6

Conjugation. Functional group is added to make the drug more easily excreted. (more water soluble). Drug is pharmacologically inactive

Question 7

Which happens faster, induction or inhibition?

Answer 7

Inhibition. [within hours. Induction may take 48-72 hours]

Question 8

6 examples of Type II metabolism.

Answer 8

“Triple G SAM” (GGG SAM) for: Glucuronidation, Glycine conjugation, Glutathionylation, Sulfation, Acetylation, and Methylation.

Question 9

What three functional groups are often involved in Phase I metabolism?

Answer 9

-OH, SH, NH2

Question 10

What noticeable effects might be seen in a PM for CYP2D6 when given antipsychotic medication?

Answer 10

Increased toxicity from lack of metabolization.

Question 11

Poor metabolizers of CYP2C19 would experience what when given PPI (proton pump inhibitors?)

Answer 11

Lack of effect. Gastric pH would remain low. Activating enzyme.

Question 12

People with CVN for CYP2D6 would see adverse drug reactions when given what drugs?

Answer 12

UM - inactivate antidepressants
PM/UM - insufficient response/toxicity from codeine
PM - drug toxicity from antipsychotics