Shortage of injectable methylprednisolone acetate

The American Society of Health-System Pharmacists reports a shortage of injectable methylprednisolone acetate. This steroid medication is used to decrease the body's immune response as necessary. It may be directly injected into joints affected to arthritis, for example. It uses are so widespread that I recommend reading them yourself in the information sheet for Pfizer's brand name version, Depo-Medrol. Neither Pfizer nor the two generic drug companies give a reason for this shortage.