Opioid Resource Center

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Disclosures: Healio Primary Care could not confirm Galinkin’s relevant financial disclosures at the time of publication.
October 19, 2021
2 min read

FDA approves opioid overdose antidote Zimhi

Disclosures: Healio Primary Care could not confirm Galinkin’s relevant financial disclosures at the time of publication.
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The FDA has approved Zimhi, a high-dose naloxone product that is administered through a prefilled syringe to counteract potentially fatal opioid overdoses, the agency and the drug’s manufacturer announced.

The approval comes amid CDC data that indicate 70.6% of the 70,630 drug overdose deaths in the United States in 2019 involved opioids. According to provisional data from the CDC, more than 99,000 Americans are estimated to have died from drug overdoses during the 12-month period that ended in March 2021.

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The FDA has approved a new treatment for preventing opioid overdose deaths, the agency said.
Photo source: Adobe stock

“I am pleased to see this much-needed high-dose naloxone product will become part of the treatment tool kit as a countermeasure to the continued surge in fentanyl-related deaths,” Jeffrey Galinkin MD, an anesthesiologist and former member of the FDA Advisory Committee for Anesthetics, Analgesics and Addiction Products, said in a press release from the manufacturer.

Zimhi (naloxone hydrochloride, Adamis Pharmaceuticals) is approved to be delivered via a “unique high dose” of 5 mg/0.5 mL, either intramuscularly or subcutaneously, the manufacturer said. The doses are stronger than those of the previously approved opioid overdose therapy Narcan (naloxone hydrochloride, Emergent BioSolutions), which is available in 0.4 mg and 2 mg doses, according to the Emergent BioSolutions website.

“The higher intramuscular doses of naloxone in Zimhi should result in more rapid and higher levels of naloxone in the systemic circulation, which in turn, should result in more successful resuscitations,” Galinkin said in the Adamis Pharmaceuticals’ press release.

Zimhi was approved through the FDA’s 505(b)(2) approval pathway. This means Adamis Pharmaceuticals submitted an application that partly relied on the FDA’s finding of safety and effectiveness of Narcan, the agency said. The approval comes approximately 2 years after the FDA denied a previous application from Adamis Pharmaceuticals for the antidote, citing concerns regarding its chemistry, manufacturing and controls, according to the manufacturer.

Zimhi should be commercially available in the United States during the first quarter of 2022, according to the Adamis Pharmaceuticals press release.

New research suggests that naloxone may be underused in the U.S. A recent study conducted by the CDC found that naloxone dispensing rates increased across all states from 0.55 per 100,000 people in 2012 to 292.21 for every 100,000 people in 2019. In addition, the average number of naloxone prescriptions per 100 high-dose opioid prescriptions increased from 0.002 in 2012 to 3.04 in 2019. Despite these increases, the study authors wrote that “dispensing rates remain low, with substantial variation and increasing disparities over time at the state level.”


Adamis Pharmaceuticals receives a complete response letter from the FDA regarding Zimhi. https://ir.adamispharmaceuticals.com/news-releases/news-release-details/adamis-pharmaceuticals-receives-complete-response-letter-fda. Published Nov. 25, 2019. Accessed Oct. 19, 2021.

Adamis receives FDA approval for Zimhi. https://ir.adamispharmaceuticals.com/news-releases/news-release-details/adamis-receives-fda-approval-zimhi. Published Oct. 18, 2021. Accessed Oct. 19, 2021.

Adamis Pharmaceuticals. Zimhi Page. https://www.adamispharmaceuticals.com/zimhi-naloxone/. Accessed Oct. 19, 2021.

CDC. Drug overdose. https://www.cdc.gov/drugoverdose/deaths/index.html. Accessed Oct. 19, 2021.

CDC. National Center for Health Statistics. Provisional drug overdose death counts. https://www.cdc.gov/nchs/nvss/vsrr/drug-overdose-data.htm. Accessed Oct. 19, 2021.

Emergent BioSolutions. Home page. https://www.narcan.com/. Accessed Oct. 19, 2021.

FDA approves naloxone injection to counteract opioid overdoses. https://www.fda.gov/drugs/news-events-human-drugs/fda-approves-naloxone-injection-counteract-opioid-overdoses?utm_medium=email&utm_source=govdelivery. Published Oct. 18, 2021. Accessed Oct. 19, 2021.

Guy GP, et al. Am Jrnl Prev Med. 2021;10.1016/j.amepre.2021.05.04.