I don't know how he could've been taking both Phenergan and Ambien and been functioning at all, unless he's built up tolerance. I've taken both- separately, not together, and not with alcohol- on rare occasions, and can't stay vertical. In fact I got very drunk on Ambien once (didn't get right into bed after taking it) and couldn't sucessfully navigate my way from my bathroom to my bedroom. Both together would probably put me to sleep permanently.
"It sounds like he is into all sorts of self-destructive behavior. I don't know what all meds he was taking, but the booze was surely not helping the depression...and taking drugs with alcohol...not good at all."
Alcohol is a depressent. It works. Alcoholics often complain of their depression. Often they get doctors to prescribe anti-depressants.
The alcoholic's mind is screwed up. He lies to the doctor, because he lies to himself and to everybody else.
And the cycle continues, until it stops.