Like others have mentioned, see if you can get compensation for the extra time / new responsibilities. If not take the job and do what you have to. Just consider yourself fortunate to have a job. And remember, it's a lot easier to look for a new job while you already have one rather than if your unemployed.
That is sort of the unfortunate thing about moving up the ladder is the higher you get, the less work you actually do and the more managing of others you do. Some people prefer to be the ones actually outputting work, while others don't mind getting paid a bit more and doing less of the day to day stuff.