This brown, round pill imprinted with GG 431 is a Amitriptyline Hydrochloride 50 MG Oral Tablet, per the NIH.
Amitriptyline Hydrochloride is a human prescription drug. The active pharmaceutical ingredient is amitriptyline hydrochloride and is classified as, "Tricyclic Antidepressant [EPC]."
This pill is made by a total of 3 firms: (1) Major Pharmaceuticals, (2) Sandoz Inc, and (3) REMEDYREPACK INC. .
There are 2 other brown pills that with a similar imprint: "GG 431". They may be a different dosage of the same drug or a different drug entirely.