I failed an entire semester the first time I went to school. Actually I was dropping out at the time and never actually dropped (Not a good idea, by the way). But, the good news is, if it was a while ago and your grades are better now, schools will look at the whole picture. Especially if you have a reason you didn't do well the first time. It would help also if you have other ways of showing you learned the material. Like if it was a chem or bio course, and you do really well on those sections of the PCAT, I don't think it's a big deal. There are plenty of other ways to make up for a blemish on your application.
