My Brother Is Taking Gabapentin, Hydrocodone (up To 4 Times

My brother is taking gabapentin, hydrocodone (up to 4 times daily), methadone (up to 4xd), ambien at bedtime and is often maxing out these meds every day and taking the midnight dose early (8-9 pm) after probably taking the previous dose at around 5pm. During the day he can have slower and slightly slurred speech, sometimes have problems finishing sentences and nod off to sleep. We have tried to get him to cut down on his meds, but he has low back pain and only decreased his daytime meds while I spent a few days with him at my urging. He has chronic CMLL, his family practitioner keeps prescribing these meds; would like your thoughts. Thank you, Jand