I think this is beta-blocker, used to regulate the heart-beat though it also has a calming effect too I think. When I saw my GP due to being anxious about my heart she fished out some half-inderal beta blockers from her desk and said that these had few side effects and that doctors even take them in A and E when they are stressed and busy. (I didn't take them in the end as I started to feel better). I would guess that if you were ok with the Propanalol you would be okay with the Sotalol. Could you compare the instruction leaflets from both? If the listed side-effects are the same it probably means they are very similar. I am always worried about taking medicines too, but I guess they have to list any side effects that came to light during drug trials however few people experienced them.