Shortages of certain medications began a decade ago, after federal agencies lowered reimbursement rates for generic drugs that treat cancer, Field said. 

“The purpose was admirable, it seems that it went too far,” Field said, adding that pharmaceutical manufacturers have turned their attention to producing more profitable drugs.

“The companies that make these drugs tend to be operating close to the margin. And if they can’t make a profit, they find a better use of their facility is to manufacture something else,” Field said. 

The author of "Mother of Invention: How the Government Created 'Free-Market' Health Care," Field is an expert on health care law and policy.