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Depression Drug Fails in First Phase 3 Trial

Neuron illustration (NIH)
(National Institute on Aging, NIH)

A drug candidate designed to treat major depressive disorder has not met its success targets in the first round of phase 3 clinical trials. The drug, TC-5214 (S-mecamylamine), is made by global pharmaceutical company AstraZeneca and Targacept Inc., biotechnology company in Winston-Salem, North Carolina.

The clinical trial tested TC-5214 as a therapy for major depressive disorder in patients who had not responded adequately to earlier treatments for depression. The study, according to AstraZeneca, did not meet its primary endpoint of change on the Montgomery-Asberg Depression Rating Scale (MADRS) after eight weeks of treatment with TC-5214 as compared to placebo.

TC-5214 addresses the overstimulation of neuronal nicotinic receptors and other receptors in the brain that are activated by the neurotransmitter acetylcholine. The drug is a nicotinic channel modulator believed to help normalize the overstimulated receptors, resulting in antidepressant effects.

Nicotinic receptors are located at synapses between two neurons and at synapses between neurons and skeletal muscle cells. When activated, a nicotinic receptor acts as a channel for the movement of ions into and out of the neuron, resulting in depolarization of the neuron.

The entire clinical trial series consists of four randomized, double blind, placebo controlled phase 3 efficacy and tolerability studies and a fifth long-term safety study. The results announced today are from a flexible dose trial conducted in Europe. AstraZeneca says, all of the phase 3 studies have completed enrollment, and reporting of results is expected by the first half of 2012.

Read more: Institutions, Companies Form Psychiatric Trial Database

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