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# Senators Urge FDA to Strengthen Opioid Studies
- URL: https://www.fdaweb.com/senators-urge-fda-to-strengthen-opioid-studies/
- Published: 2023-09-22T12:00:00.000Z
- Updated: 2026-09-14T18:57:51.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5155401

Senators **Edward Markey** (D-MA) and **Joe Manchin** (D-WV) are calling on FDA to curb the use of enriched enrollment randomized withdrawal (EERW) studies, which they say have been used to investigate opioid treatment options for patients with chronic pain but carry the risk of biasing outcomes in favor of opioid approvals.

“From members of Congress to medical experts and researchers, concerns have been raised about the safety and validity of EERW studies,” the lawmakers say in a [release](https://www.markey.senate.gov/news/press-releases/sens-markey-manchin-sound-alarm-on-potential-dangers-of-fda-enacting-opioid-treatment-investigation?ref=fdaweb.com). “According to an FDA-commissioned report, EERW studies [underestimate](https://www.dovepress.com/study-design-characteristics-and-endpoints-for-enriched-enrollment-ran-peer-reviewed-fulltext-article-JPR?ref=fdaweb.com) opioids’ adverse impacts. In April, members of the FDA’s Anesthetic and Analgesic Drug Products Advisory Committee (AADPAC) [criticized](https://www.statnews.com/2023/04/19/pain-opioid-study-design-fda-pushback/?ref=fdaweb.com) EERW studies for their potential risk of harming participating patients by introducing opioid use to patients who were previously not using opioids, prescribing and maintaining opioid doses at their highest tolerance level, and then abruptly stopping opioid use, which can induce withdrawal.”

In a [9/21 letter](https://www.markey.senate.gov/download/senators-letter-to-fda-on-eerw-trials%5F-september-2023pdf?ref=fdaweb.com) to FDA commissioner **Robert Califf**, the senators said: “Based on the risk associated with EERW studies and the availability of other study models, we ask the FDA not to permit the use of EERW to determine the long-term efficacy and tolerability of opioids in chronic pain patients. We also urge you to reject EERW study designs for any future new drug applications for opioids and reconsider past opioid approval decisions using EERW. For too long, drug manufacturers have been given the benefit of the doubt in developing and marketing a drug that unleashed a widespread, decades-long epidemic. Using a study model that risks continued bias in favor of approval is unacceptable.”