The SNRI class comprises venlafaxine and duloxetine.1 The action of venlafaxine is dose-dependent: at lower doses, it acts as an SSRI, with NA reuptake inhibition occurring at doses higher than 150 mg/day.1 However, the relative affinity of duloxetine for serotonin and NA remains the same, regardless of dose.1
References:
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2. Fagiolini A, Cardoner N, Pirildar S, et al. Moving from serotonin to serotonin-norepinephrine enhancement with increasing venlafaxine dose: clinical implications and strategies for a successful outcome in major depressive disorder. Expert Opin Pharmacother 2023; 24 (15): 1715‒1723.
3. Sansone RA, Sansone LA. Serotonin norepinephrine reuptake inhibitors: A pharmacological comparison. Innov Clin Neurosci 2014; 11 (3-4): 37‒42.
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5. Weikop P, Kehr J, Scheel-Krüger. The role of a1- and a2-adrenoceptors on venlafaxine-induced elevation of extracellular serotonin, noradrenaline and dopamine levels in the rat prefrontal cortex and hippocampus. J Psychopharmacol 2004; 18 (3): 395‒403.
6. Jakubovski E, Johnson JA, Nasir M, et al. Systematic review and meta-analysis: dose–response curve of SSRIs and SNRIs in anxiety disorders. Depress Anxiety 2019; 36 (3): 198–212.
7. Rickels K, Etemad B, Khalid-Khan S, et al. Time to relapse after 6 and 12 months’ treatment of generalized anxiety disorder with venlafaxine extended release. Arch Gen Psychiatry 2010; 67 (12): 1274‒1281.
8. Calvi A, Fischetti I, Verzicco I, et al. Antidepressants drugs effects on blood pressure. Front Cardiovasc Med 2021; 8: 704281.
