Im prescribed 15mg of zyprexa now as well, ive only been taking 10mg a day though, i hate the side effects as well, I gain weight and sleep alot longer, and feel drowsy waking up from the meds.
I dont have the symptoms of schizo day to day, it usually doesnt occur until a couple of months off my meds.
Your brother needs to either talk to his doctor about other medications or research them online, alot of people try other medications to find the best one for them.