Which of the following is an SNRI medication?

• A. Fluoxetine
• B. Escitalopram
• C. Venlafaxine
• D. Duloxetine

Answer: (D)

SNRIs work by blocking the reuptake of both serotonin and norepinephrine, increasing the levels of these two neurotransmitters in the brain to help improve mood and pain symptoms.

Duloxetine is a classic SNRI, directly inhibiting both serotonin transporter (SERT) and norepinephrine transporter (NET), giving balanced increases in serotonin and norepinephrine.

Venlafaxine is also an SNRI. Its action is dose-dependent: at lower doses it mainly inhibits serotonin reuptake, but at higher doses it significantly inhibits norepinephrine reuptake as well, providing SNRI activity.

Fluoxetine and escitalopram are SSRIs, focusing primarily on serotonin reuptake with little to no direct effect on norepinephrine.

So both duloxetine and venlafaxine fit the SNRI category; duloxetine is a prototypical example.