From the Economist:
" 'In the absence of competition, differential pricing is a hoax; scoffs Yusuf Hamied, chairman of Cipla, an Indian generics firm. In his view, only generic-makers like his firm provide genuine competition to Big Pharma..."
More correctly, differential pricing (IE, price discrimination) is not even possible with competition. If I am competing with someone, he's going to be charging a lower price than I am.