Withdrawals are usually NOT added to your GPA so you are ok....
If its not in a pre-requisite course, and if you only have 1-3 of them then most likely they will never ask about it. No student is perfect, and most schools understand this. However, if you have a bunch, especially in the beginning of your academic career, then it is very wise to address it in your pharmacy school essay.
Personally for me, my college career did not start off the strongest. However, over the last 2-3 years I accelerated in many of my classes and even ended up getting straight As my last semester before graduation. I was incredibly paranoid about my record so I decided to apply to pharm school after getting a B.S. degree and after getting a very good PCAT score (thank you Dr. Collins!!). In my personal essay I stated something in the lines of "My academic career did not start off the strongest, but I have grown and matured through my hardships and am a better student/person today because I overcame my struggles. I know exactly what I want and how valuable my future is....."
So if you confront the situation head on, then pharmacy schools will know you have nothing to hide. Also, you will be able to see which schools are genuinely interested in you as an applicant. Good luck!