Pharma group Indivior said on Tuesday that the US Food and Drug Administration rejected its nasal spray for the emergency treatment of opioid overdose. The company is reviewing the health regulator’s response.

These sprays contain naloxone, a drug that has been used to treat opioid overdose for nearly 45 years in injectable forms.

Last week, the FDA approved the first-ever nasal spray formulation of the drug made by Adapt Pharma Ltd, the Dublin-based start-up of entrepreneur Seamus Mulligan. Adapt expects to start marketing its product, Narcan, in January.

The FDA has been speeding up its review of new formulations of nalaxone to combat rising opioid abus.