There is a shortage of oncology drugs - particularly those that have been around a long time like vincristine, carboplatin, taxotere, doxorubicin and leucovorin. Oncology drugs are usually purchased by the oncologist and sold to the patient or Medicare or an insurer. Since oncology is a knowledge-based specialty rather than a procedure-based specialty, the oncologist makes his income by the mark-up between wholesale and retail prices. Medicare looked at this mark-up and thought it excessive, imposing a limit on it. This has acted as a deterrent to the prescription of generic drugs which would make the practice of treating Medicare patients uneconomic. For example the price of branded carboplatin is $120 a vial whereas generic carboplatin is $3:50. Since Medicare allows only a 6% mark-up it would cost the oncologist money to prescribe the generic.
This is the law of unintended consequences acting. Manufacturers have stopped making generic drugs and even worse, some patients have received a wrong, sound-alike, drug as a consequence. A grey-market has grown up with Indian and Brazilian generics appearing on the market.
This is not much of a problem yet in the UK, but one can see it spreading over here. I have heard of adjunct drugs that are necessary for the administration of some types of chemotherapy being unavailable in hospital pharmacies.
This story is featured in toady's NEJM.