SNRIs, NDRI, NaSSA

Question 1

Venlafaxine

Answer 1

SNRI - (EFFEXOR XR) – start 37.5-75mg (target 75-225mg, sometimes used at 300mg+)

Question 2

Bupropion

Answer 2

NDRI - (WELLBUTRIN XL) – start 150mg (target 300-450mg) ‘activating’, consider ↓seizure threshold especially in bulimic patients. Does not have sexual side effects like SSRIs. Also marketed as Champix for smoking cessation.

Question 3

Duloxetine

Answer 3

SNRI - (CYMBALTA) – start 30mg (target 60-120mg) special indication in chronic pain/ fibromyalgia. Will only be covered by RAMQ in context of chronic neurologic pain. ie. if they don’t have private insurance they would have to pay for it themselves.

Question 4

Mirtazapine

Answer 4

NaSSA - (REMERON) – start 15mg (target 30-45mg) Makes patients eat and sleep. The sedation seems to be stronger at 15mg than at higher doses.

Remeron is another antidepressant that is frequently prescribed to elderly people with depression, especially those who can’t sleep since in geriatrics we try especially hard to avoid giving benzos or antihistaminic sleep aids (do not want falls or confusion).
Mechanism: Alpha-2 receptors are pre-synaptic receptors that act as inhibitors. When the receptor is blocked by an antagonist (ie. mirtazapine), more norepinephrine is released by noradrenergic neurons and more serotonin is released by serotonergic neurons. Extra norepinephrine also stimulates the release of serotonin from serotonergic neurons.

Question 5

Desvenlafaxine

Answer 5

SNRI - (PRISTIQ) – start 50mg (target 50-400mg)

Question 6

SNRI side FX

Answer 6

sweats, nausea, dizziness, anxiety/sedation, ↑BP at higher doses.

(N.B. at lower doses SNRIs act primarily as an SSRI and therefore have a similar side effect profile. At higher doses, patients should be monitored for high blood pressure due to NE reuptake effect)