Psych Drugs

Question 1

What is the pharmacologic category of Gabapentin?

Answer 1

Anticonvulsant, misc; Gaba analog

Question 2

What is the MOA of gabapentin?

Answer 2

• Gabapentin is structurally similar to GABA (a main CNS inhibitory neurotransmitter) which means it’s a “gabapentoinoid”
• Gabapentin increases GABA synthesis
• It does not act directly on the GABA receptor, enhance GABA actions or convert to GABA.
• Acts as an inhibitor alpha2-delta subunits in voltage-dependent calcium channels which appears to be responsible for it’s anticonvulsant, analgesic, and anxiolytic effects

Question 3

How is gabapentin excreted?

Answer 3

Through the kidneys, and is structurally unchanged

Question 4

What is gabapentin officially indicated for?

Answer 4

Neuropathic pain, Postherpetic neuralgia, Partial focal seizures,

Question 5

What are off-label uses of gabapentin?

Answer 5

Anxiety, hot flashes (in menopause), restless legs, fibromyalgia, hiccups, chronic refractory cough, mild alcohol or drug withdrawal

Question 6

Generic name for Rexulti

Answer 6

Brexpiprazole

Question 7

What’s the brand name for Brexpiprazole

Answer 7

Rexulti

Question 8

Indication for Rexulti

Answer 8

1. MDD adjunct

2. Schizophrenia

Question 9

Dosing for Rexulti

Answer 9

1. MDD adjunct: Initial 0.5mg or 1mg qd x 7 days; increase to target dose of 2mg/day at weekly interval; max dose 3mg/day
2. Schizophrenia: Initial 1mg qd x 4 days, then 2mg qd x 3 days, then 4mg on day 8; max dose 4mg. Titrate based on response and tolerability between 2-4mg

Question 10

Half-life of Rexulti

Answer 10

91 hours

Question 11

Time to peak plasma levels of Rexulti

Answer 11

Within 4 hours

Question 12

Bioavailability of Rexulti

Answer 12

95%

Question 13

Metabolism of Rexulti

Answer 13

Hepatic, primarily by CYP3A4 and CYP2D6

Question 14

Excretion of Rexulti

Answer 14

Feces - 46%, ~14% of total dose as unchanged drug

Urine - 25%, <1% of total dose as unchanged drug

Question 15

MOA of Rexulti

Answer 15

Partial agonist activity for Serotonin 5-HT_1A and Dopamine D_2 receptors

Antagonist activity for Serotonin 5HT_2A receptors

Question 16

General Price of Rexulti w/o insurance

Answer 16

$44.38/pill (regardless of dose)

~$1,100 with GoodRx

Question 17

Dosage forms of Rexulti

Answer 17

0.25mg, 0.5mg, 1mg, 2mg, 3mg, 4mg

Question 18

Do you have to take Rexulti with or without food?

Answer 18

It doesn’t matter, you can take it with or without food

Question 19

Rexulti adverse reactions

Answer 19

> 10%:
CNS - Akathisia (4%-14%; dose related)
Endocrine and metabolic - inc serum triglycerides, weight gain (3%-11%)

1%-10%
CNS - HA, EPS, drowsiness, fatigue, dizziness, anxiety, restlessness, sedation, abnormal dreams, insomnia

Derm: hyperhidrosis

Question 20

What are the 6 main CYP450 enzymes and what percent of drugs do they metabolize?

Answer 20

• CYP: 1A2, 2C9, 2C19, 2D6, 3A4, 3A5

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