Propofol
"I had my second colonoscopy at age 61, this time with Propofol (Diprivan) and it went much better than the first one ten years earlier with a different sedative (when I woke up in the middle of the procedure in considerable pain).  It was injected into an IV in the back of my right hand and I was literally out like a light in about ten seconds.  The next thing I knew I was in the recovery room and I couldn't believe it was over.  The only side effects were a sore throat (I had on an oxygen mask so that may have been a contributing factor) and very low blood pressure for about thirty minutes afterwards."