Taking 5 mg bystolic (nebivolol) @ 8 pm causing low pulse rate day 50 to low 60 and while sleep high 30 to low 40 . can amlopdipine be substitute if you have cad.

Yes but: Amlodipine is beneficial in CAD but uses a different mechanism than bystolic (nebivolol). Amlodipine won't slow your heart at all. If you have angina, a bb is preferable. If you don't have angina, amlodipine is a good alternative.

NO: As long as you are not tired and symptomatic your low heart rate is not a problem. If you are you can consult your doctor for a different beta blocker or a lower dose.