Re: "Iron Man 3" Review and Discussion Thread (spoilers)
That's certainly a possibility, but I'd say the movie is very unclear (at best) on whether that actually occurs as a side effect or not. I think Pepper was surprised that she survived thanks to Extremis and that she actually had some fun using part of the Mk 42, but I didn't see anything that was a specific personality change. I have no clue if the substance ever appeared in the comics, so perhaps someone with more experience can answer that.
"If you think you're brave enough to walk the path of honor, then follow me into the dragon's den."