(Bloomberg) -- US regulators, coping with more than 100 drug shortages, don’t have enough information to predict which medications will run low next, according to an analysis discussed in a Senate committee Wednesday.

Components of the supply chain — including where drugs are made and the reasons manufacturers can’t produce them — aren’t always made public, lawmakers and expert witnesses said in a Senate Committee on Homeland Security and Governmental Affairs hearing. That makes it difficult to understand and prevent medication shortfalls, they concluded.

Michigan Senator Gary Peters, a Democrat who chairs the committee and whose staff wrote the report about drug shortages, said he plans to introduce new legislation based on the findings.

“Both the pharmaceutical industry and the federal government, including the Food and Drug Administration, lack the information needed to effectively detect and to prevent shortages,” Peters said at the hearing.

Over the past year, several common medications, such as the antibiotic amoxicillin and the attention-deficit/hyperactivity disorder drug Adderall, have been in short supply, bringing political focus on a recurring problem. 

The pharmaceutical industry has long failed to produce sufficient quantities of some needed medicines — every year, dozens of drugs fall into short supply, according to the FDA. More than 15 critical drugs have been in shortage for over a decade, according to the staff report.

On Tuesday, the FDA listed at least 120 treatment shortages on its website, including antibiotics, anesthetics, psychiatric drugs and more. At the end of 2022, the US reached a peak of 295 active medication shortfalls, according to an analysis using different methodology, from the University of Utah’s drug information service. 

There are a variety of reasons why drug shortages persist, such as low profit margins for old generics, quality issues with manufacturing and increases in demand for certain medicines, according to the report. The analysis also points out weaknesses that make prevention harder.

Currently, drugmakers are required by federal law to tell the FDA — the agency that approves new drugs and tracks shortages — when the supply of their medications might be disrupted. The agency takes steps to prevent supplies from running too low and, if those fall short, posts online when it concludes the overall need for a certain medication is not being met.

Catching shortages before they happen is challenging because pertinent details, such as where some raw ingredients and inactive substances are produced, are sometimes “buried in PDFs,” according to the report. The FDA is working to put that information in a database, but it will still lack important context. Federal law doesn’t require manufacturers to tell the FDA how dependent they are on each supplier.

In its fiscal year 2024 budget request, the FDA included legislative proposals to improve transparency, such as requiring companies to report increases in demand that might lead to shortages. It also suggested requiring companies to extend drug expiration dates when it’s safe to do so.

(Updates with details from hearing starting in second paragraph.)

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