Drugs - SSRI

Question 1

What is the method of action of SSRIs?

Answer 1

Down regulate (desensitize) 5HT1A and 5HT1B/1D autoreceptors

Question 2

Which are the SSRIs?

Answer 2

• Fluoxetine (Prozac)
• Sertraline (Zoloft)
• Paroxetine (Paxil)
• Citalopram (Celexa)
• Fluvoxamine (Luvox)

Question 3

What are the characteristics of fluoxetine?

Answer 3

• Activating –> causes agitation, restlessness, insomnia
• takes five weeks for drug and metabolite to reach steady-state therefore you should allow five weeks for washout before switching to MAOIs to avoid serotonin syndrome
• blocks more CYP450 isoforms than any other SSRI

Question 4

What are the characteristics of sertraline?

Answer 4

• Significantly less inhibition so less drug interactions (similar to citalopram)

Question 5

What are the characteristics of paroxetine?

Answer 5

• Potent SSRI, more sedating than most others
• worse for causing sexual dysfunction
• no active metabolites (most others do have)
• withdrawal effects may be profound (similar to Venlafaxine) –> dizziness, nausea, parathesias, tremor, anxiety –> more symptoms with short half-life drugs
• very potent CYP2D6 inhibition (more than fluoxetine)
• some mild anticholinergic effects
• most potent inhibitor of serotonin reuptake

Question 6

What are the characteristics of citalopram?

Answer 6

• Little ability to inhibit CYP450 enzymes
• Less likely to cause agitation and nervousness
• Lexapro is the pure S-enantiomer of citalopram, with little education, little side effects, and mild withdrawal symptoms. It is the most potent SSRI

Question 7

What are the characteristics of Fluvoxamine?

Answer 7

• Approve use in the treatment of OCD (can use any SSRI)

- Potent CYP1A2 inhibitor