The IMS report found great volatility in the availability of some drugs in recent years, likely linked to the simple fact that some drugmakers just stopped making those medicines.
Although almost 100 companies in all were supplying the 168 products in short supply, half of those drugs were made by only one or two suppliers, the report found.
Of the troubled 75, a single company or two companies were supplying 65 percent of them, Aitken said.
"Some (companies) have decided to stop production of these types of drugs, and if it leaves one or two suppliers, that doesn't provide a lot of flexibility when one might have a manufacturing problem of some sort," he said.
"Part of the story is there may not be sufficient economic incentive currently in this sector of the market."
The corporations supplying the most number of drugs from the shortage list were Hospira Inc and Teva Pharmaceuticals USA. Others included Novartis AG , Watson Pharmaceuticals, Pfizer and Baxter Healthcare, according to the report.
Tuesday, November 15, 2011
Study finds U.S. drug shortage problem concentrated - Business - msnbc.com