Most drug shortages are the result of quality issues tied to manufacturing problems, but once in a while it is the result of demand overwhelming supply. That is what has happened with Biogen Idec's ($BIIB) new multiple sclerosis pill Tecfidera. Apparently there have also been some supply-chain and manufacturing snags that have affected distribution, but doctors and patients are clamoring for the expensive drug, which some say is the most anticipated MS treatment in 15 years. Story | More