γ-Aminobutyric Acid Amides of Nortriptyline and Fluoxetine Display Improved Pain Suppressing Activity

The GABA amides of the antidepressants nortriptyline and fluoxetine, 1 and 2, were compared to their respective parent compounds in rodent models of pain. The amides significantly reduced early nociceptive and late inflammatory responses compared to nortriptyline or fluoxetine, where 1 exhibited overall better efficacy than 2. Amide 1 was most efficacious in lowering cytokine secretion, edema and hyperalgesia induced by formalin and λ-carrageenan, respectively. Thus, 1 is a promising candidate for the treatment of pain.