Ketamine is a drug that has evolved since it was originally used as an anesthetic for humans and animals. It can be used to treat severe depression, but also as a psychedelic “party drug,” according to NPR.

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The drug took center stage on Friday after the Los Angeles County Medical Examiner released an autopsy report that stated “Friends” actor Matthew Perry died from the “acute effects” of ketamine.

Perry, 54, known for his role as Chandler Bing on the sitcom from 1994 to 2004, was found unresponsive in a hot tub at his Los Angeles-area home on Oct. 28, according to the Los Angeles Times.

His manner of death was ruled an accident, according to the medical examiner.

Perry’s autopsy report stated that the actor was going through “ketamine infusion therapy,” according to The New York Times. His most recent therapy was more than a week before his death. The report noted that the ketamine in Perry’s system could not have been from his last known therapy session, according to the newspaper.

Here are some things to know about ketamine.

What is ketamine?

According to the U.S. Drug Enforcement Administration, ketamine is defined as a dissociative anesthetic that has some hallucinogenic effects. The medication alters the perception of sight and sound, making users feel detached from their pain and environment.

“Ketamine can induce a state of sedation (feeling calm and relaxed), immobility, relief from pain, and amnesia (no memory of events while under the influence of the drug) and is abused for the dissociative sensations and hallucinogenic effects,” the DEA said on its website. “Ketamine has also been used to facilitate sexual assault.”

It was developed in the 1960s as a battlefield anesthetic, according to The New York Times.

“People shouldn’t be afraid to use ketamine if it’s prescribed by their physician and it’s delivered correctly in a health care setting,” Gerard Sanacora, director of the Yale Depression Research Program and co-director of the Yale New Haven Hospital Interventional Psychiatry Service, told the newspaper.

What are some of its nicknames?

The DEA notes that ketamine is known by several street names. Common nicknames for the drug include Special K, Super K, Vitamin K, Cat Tranquilizer, Cat Valium, Jet K, Kit Kat, Purple, Special La Coke and Super Acid.

How is ketamine used?

Ketamine can either be injected into a person’s system or taken in a powder form, according to CBS News. In its powder form, the drug can be smoked, snorted or mixed into drinks, the news organization reported.

The approved medical product is used as an injectable short-lasting anesthetic for people and animals, USA Today reported. It also can be used as a nasal spray for treatment-resistant depression.

The drug typically comes in a clear liquid or as a white powder, according to the DEA. When used as a powder, the drug is usually packaged in small glass vials, capsules or small plastic bags. It has also been found in paper or aluminum foil folds, the agency stated.

Ketamine can be used by itself or in combination with methamphetamine, cocaine, MDMA or amphetamine, according to the DEA.

Is ketamine legal?

According to the DEA, ketamine has been marketed in the United States since the 1970s as an injectable, short-term anesthetic for use in humans and animals. In 1999 the drug, including its salts, isomers and salts of isomers, became a Schedule III non-narcotic substance under the Controlled Substances Act.

The U.S. Food and Drug Administration said that ketamine is not approved by the agency for the treatment of any psychiatric disorder.

The FDA said it was aware that compounded ketamine items have been marketed to treat depression, anxiety, and post-traumatic stress disorder, However, the agency said the drug had not been determined as safe or effective yet.

“It really decreases your consciousness, and with that it can have cardiovascular changes and respiratory depression,” Lisa Harding, a psychiatrist at the Yale School of Medicine who treats patients with ketamine, told The Wall Street Journal. “This is a treatment that saves lives, but it has to be done with the right patient and it has to be done in the right place.”

In 2019, the FDA approved a nasal spray version of ketamine, called esketamine and marketed as Spravato, for treatment-resistant depression. The spray is only available at a certified doctor’s office or clinic. The drug does have the potential for abuse, the DEA states.

The medicine’s purpose was to treat depressive disorders if at least two alternative antidepressant treatments did not work, USA Today reported.

What are the benefits of ketamine?

In 2006, researchers at the National Institutes of Health issued a report that stated that an intravenous dose of ketamine could relieve severe depression in a few hours, NPR reported. That was much faster than other depression remedies, including Prozac and Zoloft. Those drugs typically take several weeks to help a patient’s condition, according to the news outlet.

What are the dangers of ketamine?

In October, the FDA issued an alert, warning about the dangers of treating psychiatric disorders with compounded versions of the drug, The New York Times reported.

The DEA said that some users taking ketamine could experience an increased heart rate and blood pressure. Side effects also included involuntary rapid eye movement, dilated pupils, salivation, tear secretions, stiffening of the muscles and nausea.

“An overdose can cause unconsciousness and dangerously slowed breathing,” the agency said.

The FDA noted that in clinical trials, patients who were treated with Spravato experienced several side effects. They included disassociation, dizziness, nausea, sedation, vertigo, decreased feeling or sensitivity (hypoesthesia), anxiety, lethargy, increased blood pressure, vomiting and a feeling of drunkenness.

Another high-profile ketamine case

Elijah McClain died after he was stopped by three police officers while he was walking home in Aurora, Colorado, in August 2019.

McClain, 23, was put in a neck hold, and two Aurora Fire Rescue Paramedics called to the scene administered at least 500 milligrams of ketamine to him, KDVR-TV reported. McClain’s heart stopped while he was in an ambulance and he never regained consciousness. He was pronounced brain-dead and died on Aug. 27, 2019, according to NPR.

A trial involving several felony charges against the paramedics, Peter Cichuniec and Jeremy Cooper, is ongoing, NPR reported.

The trials for Aurora Police Officers Jason Rosenblatt and Nathan Woodyard ended in acquittals, according to The Denver Post. The third officer, Randy Roedema, was found guilty of criminally negligent homicide and third-degree assault, according to KMGH-TV.