A Duluth clinic is discontinuing a form of treatment for depression and mood disorders, and patients are raising an alarm.

"I genuinely believe this will kill at least one of the 30 to 40 current patients, if not more," said Andrew Ronding, 36, in an email.

Essentia Health confirmed that treatment with ketamine infusions has been provided at the Essentia Health-Duluth Clinic 2nd Street Building by Dr. Michael Messer, a psychiatrist. Messer retired on Monday.

"Few physicians prescribe ketamine for the treatment of depression and mood disorders because it is not currently FDA-approved for this use," Essentia said in a statement. "Since learning of this physician's retirement plans, we have reached out to other providers and health systems in the area to see if they would be willing to provide ketamine treatments for these patients until we are able to recruit a new provider. So far, all have declined."

Ketamine is a psychedelic drug that has appeared in a number of different guises. Originally used as the anesthetic of choice for children, it later showed up as a party drug (with street names such as Special K) and, more recently, as a non-conventional treatment for depression and suicidal impulses.

Some research has shown ketamine to be quickly effective in treatment for someone who is "very suicidal," said Sue Abderholden, executive director of the National Alliance for Mental Illness in Minnesota. It also has been found to help people with "treatment-resistant" depression, she said.

Thomas Insel, former director of the National Institute of Mental Health, wrote on the agency's website in 2014 that ketamine "might be the most important breakthrough in antidepressant treatment in decades."

Although questions still needed to be resolved, Insel wrote that studies had shown ketamine to be effective when other treatments weren't for "some of the most disabling and chronic forms of depression."

The difference it made for her was "phenomenal," said Brenda Eng, 56, who lives in Duluth's Endion neighborhood.

"To go from staying in my bedroom 24 hours a day, seven days a week, going for days and not talking to anybody, seeing anybody - to going out and doing things on my own and talking to people," Eng said of what she experienced from infusions that began for her on Jan. 20, 2014.

What had been mild depression had become much more intense for Eng after she was diagnosed with multiple sclerosis in 2004, she said. After a number of medications proved ineffective over the years, she asked Messer about electroconvulsive therapy (ECT). He advised against that in her case, she said, concerned that it might cause a relapse in her MS. He suggested ketamine as a possible alternative. She researched it and agreed to try it.

After an initial adjustment period, she settled into a regular pattern of being infused once every two weeks, Eng said. Although she continues to suffer from depression, it helps her to handle the symptoms.

Ronding, who said he was diagnosed with depression at age 15, also was placed on ketamine infusions only after numerous other medications had proven to be ineffective for him. He planned to receive ketamine treatments for the rest of his life "since they seem to be working more than the medications and other treatments I had tried," he wrote.

ECT is offered at St. Luke's hospital, Ronding wrote, but not ketamine. A St. Luke's hospital spokeswoman confirmed that.

Messer's retirement means patients will either have to go to Minneapolis or to the Essentia Health-Ely clinic for treatment, Eng said. She's waiting to hear if the Ely clinic will be able to fit her in, she added.

Ronding wrote that he fears many patients won't be able to travel for treatment. The process takes two to three hours and the infusion must be given on an empty stomach, he said. Moreover, the patient can't drive afterward. The treatments are needed frequently - in his case, between one and four times a month.

Ronding contended Essentia Health has offered the treatment to hundreds of people over several years, and currently treats about 40 patients. But Eng said she understands the number being treated is 29.

An Essentia spokeswoman declined to comment on the number of patients, but in its statement, the health system said, "Essentia Health is doing everything in our ability to serve these patients, and we are looking at several options."

Monday was a poignant day for Eng. She received a ketamine infusion on Messer's last day of work.

"I cannot say enough about the nurses who work there," she said. "They're part of my family, and it was so sad to say goodbye to them."

Ketamine has been in the news in the Twin Cities recently, but for other reasons. In June, Hennepin County Medical Center suspended a clinical trial on using ketamine as a sedative in emergency situations, the Associated Press reported. The hospital had come under fire for enrolling patients in the study without their knowledge.

Separately, an independent investigation commissioned by the city of Minneapolis was looking into the fact that the number of documented ketamine injections during police calls had grown from three in 2012 to 62 in 2017.

But those are entirely different uses of ketamine than its use in treatment for depression, Abderholden noted.