Gaba M 300 mg/500 mcg A combination medication called a capsule is used to treat neuropathic pain. A combination of medications called Gaba M 300mg/500mcg Capsule is used to treat persistent (chronic) pain brought on by nerve damage from spinal cord injuries, diabetes, or shingles. It lessens pain and the symptoms that go along with it, like mood swings, difficulty sleeping, and fatigue. It is believed to function by disrupting the pain impulses that pass via the brain and damaged nerves. Regular use of this medication will enhance your general quality of life as well as your social and physical functioning.