Current prescription drug shortages in the US, while disruptive and of increasing concern, are limited primarily to generic injectables and a few key disease areas, a new study has found.

"Patients throughout the US, including hundreds of thousands being treated for cancer, may be at risk of treatment disruption due to drug shortages," says Murray Aitken, executive director of the IMS Institute for Healthcare Informatics, which produced the study and is calling on healthcare stakeholders to work toward the creation of an early-warning system to minimise future patient care disruptions.

The study finds that the drug shortage problem is highly concentrated. Over 80% of products impacted are generics, and more than 80% are injectables. While the affected products represent a small part of the overall medicines market, they include a number of critical drugs used to treat cancer, infection, cardiovascular disease, central nervous system conditions and pain. Oncology drugs make up 16% of the products in short supply, it adds.

Moreover, while the shortages involve a large number of suppliers, most drugs in short supply have only one or two manufacturers. Over 100 companies supply 168 products included on the shortage lists compiled by the Food and Drug Administration (FDA) and the American Society of Health System Pharmacists (ASHSP), but 51% of those products have only one or two suppliers. 

13 companies have stopped supplying products on the shortage lists within the last two years, and this leaves a growing number of products open to possible production disruptions that cannot be offset rapidly by other producers, says IMS.

Moreover, while total supply volume for many impacted products has been stable or growing, there is significant volatility among suppliers, the report notes. The total monthly supply volume for all products on the shortage lists has increased 4% over the past five years, while for more than half of the listed drugs, total supply is relatively stable or has increased. However, IMS finds recent signs of increased volatility in the month-to-month supply of impacted products by specific suppliers, resulting in disruption to providers.

The study also shows that, for a group of 75 drugs, supply volume has fallen substantially. Compared with a three-year base period ending in 2009, a subset of products has experienced supply declines of more than 20% in recent months. The per-capita supply of injectables has fallen more than 30% in 13 US states, suggesting significant treatment protocol disruption for patients, it adds.

The report calls on the FDA or healthcare industries to establish an early-warning system to improve drug supply monitoring and says that this should include a volatility index, risk identification, demand forecasting and predictive modelling.

'Healthcare stakeholders involved in the supply chain can best tackle this issue by working together in a focused manner. With targeted structural improvements and an early-warning system in place, patients will have greater assurance that their treatments will not be disrupted," said Mr Aitken.

Meantime, the American Medical Association (AMA) has this week adopted a policy to combat the shortages, which it has described as a national public health emergency.

At its semi-annual policy-making meeting in New Orleans, the AMA voted to back bills put forward in the House of Representatives and the Senate that would require manufacturers to notify the FDA of any discontinuance, interruption or adjustment in the manufacture of a drug that may result in a shortage. The new policy also calls on the AMA to advocate that the FDA and/or Congress should require drugmakers to establish a plan for continuing of supply of vital and life-sustaining medications and vaccines to avoid production shortages whenever possible.

However, a draft resolution which called for drugmakers to pay fines if they did not increase production of a drug in short supply within 30 days was not taken up, and the AMA proposed instead that manufacturers should receive financial incentives to continue producing such medicines.