Sorry to hear that man. This is why I think many who find themselves struggling with depressive conditions - when it isn't just a passing low feeling, but instead feels like your body simply isn't producing the required brain chemical balance to function - are extremely reluctant to dive into the foggy world of strong prescription meds. I personally think it has to be a last resort once all other avenues and milder pharmaceutical applications have been exhausted.
It's worth sticking with it through a period of discomfort using less heavy medicines, to see if you can adjust more naturally. Obviously if you can't, after a decent span of time given to trying, and if you reach a genuine crisis point (not during a particularly stressful moment, but in your downtime when you should by rights be feeling relaxed and okay), then you have to try the next step up in treatment. Sounds like your bro needs to try something new to help him out of this rut, if only to give him some renewed hope.
Try to look into new trials for treatments that may be on the horizon, so that he feels it's worth holding out just for a better chance at treating the illness further down the line - in the meantime, he might find himself stumble across some better days here and there, while he's waiting for that magic bullet treatment to emerge. Better that than denying himself the opportunity to ever make any recovery. It's hard to get through to people going through what he is, I know, but what he requires is
hope, and if he can't generate it himself, he needs it fed to him. Good luck, man.
Depression. It's a fucking bastard I tell you.
Perhaps the ultimate fucking bastard, given that it diminishes or removes entirely the ability to appreciate the beautiful moments that are there for you to experience, while otherwise having a perfectly fuctional physical vessel in which to experience it - you have all your working organs, limbs, vision, hearing, etc. but you cannot
live.
However long it may feel like it lasts though, it is not a permanent state of being, and you all will have opportunities to feel alive again, there will always be moments like that to come, wherever you are now and however bleak the future may look. Death by your own hand forfeits all of that for a brief bit of relief from an impermanent state of torment. Not a good deal, on reflection.