Very interesting - drug induced night cramps are of course very different from running but I can see where you are coming from. I imagine the medication increased salt excretion. If it was for blood pressure having extra salt may have partly negated the benefits. It is very hard to have a diet that is too low in salt - we evolved in a low salt environment and our bodies are used to getting by on very little - most people in Western Society have far too much, hence our tendency to high blood pressure etc - with potassium it is the opposite - as long as your kidneys are OK and you are not on certain medications it is difficult to have too much.