Price discrimination is a very common type of pricing strategy engaged in by those businesses who have any control over their pricing, which includes most of them. "Price discrimination is a policy where a seller sets different incremental margings on various units of the same or similar prudcut. " (Managerial Economics, 3rd Edition, 2007. Png & Lehman. Pg 231.)
Pharmaceutical companies are no different in that the firm's profits are generally the main motivating factor behind pricing decisions. If pharmaceutical companies were not able to engage in price discrimination, who knows what potential life-saving medicines may never actually make it to market. Pharmaceutical companies, by the very nature of their business, have much higher R&D expenses, and as such, have price structures set well before a medicine makes its way to the pharmacy or store shelves.
The article, Pharmaceutical Price Discrimination and Social Welfare, http://www.bepress.com/cas/vol5/iss1/art2/, authored by Frank Lichtenberg, pointed out that people in the lowest income bracket pay 25% less than high income people. However, people in the middle income bracket pay 6% more than those same high income people. This should be an area of concern for regulators, or someone, in my opinion, as the middle income bracket appears to be bearing the higher burden. I will admit though, that I am very biased on this matter as I have a young daughter with major health issues. The most recent medicine the neurologist started her on comes with a jaw-dropping invoice each month. The pharmaceutical companies charge it because they can. Plain and simple. That does not make it right or fair, obviously, but how often in life is everything fair? I would pay whatever I was invoiced, as I have placed the opportunity costs of not having my daughter in my life as much, MUCH higher than the money that may or may not be residing in my pocket book.
The ability of these firms to price discriminate increases the chances that more medicines have a chance to make it to market, which will hopefully save or improve more lives, including my daughters. If these firms were regulated as to what "had" to be charged, the R&D process might be halted too soon for any benefit to ever be realized.