First I take one month proponl sustain release tablet 20 mg and than half of it for 5 months but I got to know that we should not take half of it so I start taking propanal 10 mg once a day for 15 days and since week twice a day Can we switch again to propanal sustain release tablet 20 mg  first i am taking 10 mg propanal and than started twice a day but it not benefit as soon as effects goes off pulse rate increase so can we switch propanal sustain release 20 mg from immediate release and is there will any side effects or not from switching immediately release to sustain release tablet or safe to switch