What is a brown pill with m36 on one side?

Not Medical Advice: A round brown pill with the imprint M 36 is 50mg of Amitriptyline hydrochloride. The tricyclic antidepressant treats fibromyalgia, insomnia, depression, pain, anxiety and stress. Side effects: nausea, vomiting, constipation, diarrhea, dry mouth, loss of appetite, blurred vision, headache. Drug interactions: Ambien, Celebrex, Cymbalta, Lyrica, Lexapro, Lipitor, Singulair, Topamax and more. Avoid mixing alcohol with Amitriptyline hydrochloride. Thinking and reactions may become impaired.

Monday, February 06 2012
Source: http://www.drugs.com/imprints/m-36-7840.html