(Reuters) - Trevena Inc shares plunged 45 percent on Friday after the U.S. Food and Drug Administration declined to approve its opioid injection for managing acute pain, citing inadequate safety data.

The widely expected rejection comes after a panel of experts to the FDA voted against the approval of the drug due to lack of safety data and potential for abuse, at a time when opioid addiction in the country has reached epidemic proportions.

In a complete response letter, the FDA asked the company to provide additional clinical data and indicated that the submitted safety data is not adequate for the proposed dosing.

The health regulator also requested certain additional nonclinical data and validation reports.

Trevena’s oliceridine belongs to the same class of opioids as commonly used painkillers such as morphine and fentanyl.

Addiction to opioids is a growing problem in the United States, especially in rural areas. According to the Centers for Disease Control and Prevention, opioids were involved in more than 70,000 deaths in the country last year.

In its efforts to curb opioid abuse, the FDA has been encouraging drugmakers to develop alternatives to addictive painkillers, while declining to approve new opioid therapies.

Most recently, Pain Therapeutics’ abuse-deterrent opioid treatment was rejected for the fourth time.

Separately, the FDA on Friday approved AcelRx Pharmaceuticals Inc’s similar treatment for use in medically supervised settings.

Trevena, which is also developing an oral version of oliceridine and a potential treatment for migraine, said it plans to schedule a follow-up meeting with the FDA as soon as possible.