>>Alex39+(OP)
Several factors: aging of the inmate population (and higher probability of chronic illness, but people imprisoned under 3 strikes cannot b released on medical parole); higher cost of care in general, for the same reason that health insurance costs have risen; and large payouts for wrongful-death lawsuits due to medical negligence, and subsequent overhaul of prison care. Medical and pharmaceutical services are usually provided by specialty companies that sell both clinical and security expertise. Being a prison doctor pays about $250k/year. Most of the expense goes on a very small percentage of the prisoners, as end-of-life care is the most expensive kind.
http://articles.sfgate.com/2010-05-19/news/20904260_1_sick-i...