FDA has approved Cyberonics’ proposal to amend the protocol of its D-21 post-approval dosing study in depression patients treated with VNS Therapy.

Reportedly, the company submitted a proposal in November 2008 to reduce the number of study subjects from 460 to 330, and completed enrollment of 331 study subjects in February 2009.

With this decision from the FDA, the company expects to complete the follow-up on all patients enrolled in the study by March 2010.

Cyberonics developed and markets the Vagus Nerve Stimulation (VNS) Therapy System, FDA-approved for the treatment of refractory epilepsy and treatment-resistant depression.

VNS Therapy System uses a surgically implanted medical device that delivers pulsed electrical signals to the vagus nerve.