Food & Drug Interactions

Question 1

Which 3 SGA’s must be taken with food or exposure to medication is reduced by 50%?

Answer 1

Lurasidone Latuda 350kcal
Vilazodone Vybrid
Ziprazidone Geodon 500kcal

Question 2

Name medications that must be taken without food

Answer 2

Z-drugs

Levothyroxine

Quetiapine ER

Question 3

What happens when Seroquel XR is taken with a full, especially high fat, meal

Answer 3

The peak concentration increases to 1.5 times!!! This is only an advantage if you want to have higher peak concentration to take advantage of hypnotic affects in the case of insomnia

Advantage of Seroquel XR over Seroquel IR both taken on empty stomach, peak concentration is 60% lower even though they are getting the same amount of medication. This reduces side effects, such as sedation, and improves tolerability.

Seroquel XR should be taken without food to reduce side effects but it also decreases it’s hypnotic affect

Question 4

What happens when zolpidem is taken after food?

Same with esopiclone

Answer 4

Peak level is 25% lower and time to peak level is increased from 1.4 hours to 2.2 hours

Question 5

When taken with food, exposure to BuSpar and paliperodone (Invega) will be…

Answer 5

Increased. Take consistently with or without food

Question 6

What happens when lisdexamphetamine or other amphetamines are taken when urine is highly acidic (possibly from high vitamin C intake)?

Answer 6

Excretion is significantly increased by up to 60% thereby blood levels are decreased

This does not apply to methylphenidate

Advise discontinuation of high-dose vitamin C supplement when taking amphetamines

Question 7

Caffeine inhibits CYP450…

Major meds this affects

Answer 7

1A2 (Primary enzyme that metabolizes clozapine

May need to decrease clozapine dose if begins to consume larger amounts of caffeine. If patient quit caffeine, may need to increase clozapine dose

Olanzapine possibly

Question 8

Which SSRI increases the half-life of caffeine, but not its Effects

Answer 8

Fluvoxamine

Question 9

Smoking……CYP 1A2

Opposite of caffeine

Answer 9

Induces

This is why smokers need four times more coffee

Clozapine affected by this. If a patient quit smoking, Clozapine dose will likely need to be reduced

Question 10

Lithium and caffeine interaction

Answer 10

Caffeine increases urinary excretion, therefore if patient increases caffeine intake lithium dose May need to be increased

Question 11

Lithium tremor and caffeine

Answer 11

Patients are often told to decrease caffeine intake to reduce/eliminate tremor.

Reducing caffeine intake then increases lithium levels which in turn may actually increase tremor.

Therefore in the case of tremor, decreased lithium dose

Question 12

Grapefruit/grapefruit juice….. CYP450 enzyme….

Medications affected….

Answer 12

Inhibits 3A4 irreversibly

Occurs with even just one grapefruit or one cup of juice

Effect lasts for up to three days Until new enzyme is created. Affects both absorption and metabolism since some of the enzyme is in the small intestine as well as in the liver

BuSpar Exposure increased 9x

Diazepam Exposure increased 3x

Carbamazepine increased 1.5 X
Lurasidone, Quetiapine

Question 13

Turmeric….CYP450….

Answer 13

Inhibits 1A2

Question 14

Another 3A4 inhibitor…..tea

Answer 14

Chamomile

Chamomile tea increases effects of benzodiazepines, Z-drugs, BuSpar

This may be an advantage for patients in that if they take their sleep medication with Chamomile tea, they may be able do use a lower dose of the medication as a chamomile tea will boost the efficacy

Question 15

Grapefruit inhibits 3A4 and increase his levels of B, C, D. What are the names of these drugs?

Answer 15

BuSpar, carbamazepine, diazepam