The following explanations for drug shortages were provided by the U.S. Food and Drug Administration (FDA). They have been edited for length.
Raw and Bulk Material Unavailability. Disruptions can occur in the availability of raw and bulk materials to manufacturers of finished drug products. This is especially problematic when multiple manufacturers make a drug product with material available from only one source.
Manufacturing Difficulties. Shortages can occur when the primary or only manufacturer of a drug product halts production in response to an FDA enforcement action concerning noncompliance with Current Good Manufacturing Practices.
Voluntary Recalls. Voluntary recalls can cause shortages, especially when a sole manufacturer’s drug product dominates the market supply. Voluntary recalls usually affect specific lots.
Unexpected Increases in Demand. Occasionally, an unexpected increase in demand for a drug product exceeds production capacity.
Manufacturer Production Decisions. Manufacturer production decisions can cause shortages. Occasionally, manufacturers temporarily or permanently reduce production amounts of certain drug products as they shift production or reallocate resources to other products. An apparent practice among some manufacturers has been the halt of production when annual quotas are met. A manufacturer’s reasoned, sound business decision to discontinue production of a drug product because of insufficient financial return can cause a shortage. Under this circumstance, FDA might perform a medical necessity evaluation and, if the unavailability of the product puts the public at risk, encourage other manufacturers to produce the product.
Nontraditional Distributors. The shortage of drug products has attracted several nontraditional distributors who have been able to obtain certain products. When demand exceeded supply through normal channels, these distributors announced the availability of these products at substantially higher prices. How they obtain these products and whether their activities contribute to shortages is unknown. Compounding pharmacies also have announced the availability of drugs that are in short supply. Caution is warranted because preparations from these pharmacies may not have FDA-approved labeling, and their sources of raw materials have been questioned.
Orphan Drug Products. Drug products used to treat rare disorders for a relatively small patient population might be difficult to obtain.
Natural Disasters. Natural disasters cause drug product shortages when they affect manufacturing facilities, particularly those of manufacturers that are the sole source for a drug product or category of products.
Restricted Drug Product Distribution. An increase in the number of drug products available only through restricted distribution methods has caused artificial shortages for some health care organizations.
Industry Consolidations. Manufacturer mergers often result in decisions to narrow the focus of product lines, resulting in the discontinuation of drug products. In addition, merged manufacturers of competing products may consolidate production, making product supply more vulnerable should problems arise.
Market Shifts. The addition of a generic product to the market can precipitate a decrease in the production of the innovator product.