My doc prescribed Valium for me in 2 mg doses. Does anyone know if Klonopin is more effective? Xanax is the king of prn (as-needed) anti-anxiety meds, lasting only several hours and not accumulating in the way Valium. I recently switched from Klonopin to Valium w/30 2mg Xanax. I was prescribed 2 anxiety meds, Clonazepam and Diazepam, daily. Is it safe to. I think they're about the same strength with the same long-acting effects. Diazepam just has a wider variety of uses than Clonazepam's uses.