Melbourne researchers have embarked on a major trial investigating a promising new drug treatment for Post Traumatic Stress Disorder; a condition affecting 800,000 Australians.

N-acetylcysteine, also known as NAC, has shown great promise as medication for reducing PTSD symptoms;  after an initial trial involving two dozen US veterans saw a 32 percent improvement in their symptoms, compared to 3 percent given a placebo.

A Melbourne study will involve 126 participants with PTSD who have been resistant to other medications and treatments.