When I took the GRE, I memorized the 300 most common words for the GRE. My verbal score went up 150 points, which was great and definitely beneficial.
However, with 6500+ words, you should balance the opportunity cost; Your score will improve, but it's only 1/5th of the exam. I'd spend more time memorizing Biology & Chemistry information, which is more important to Pharmacy schools, versus increasing your Verbal score a few points.