What is ketamine? A doctor explains the drug involved in Matthew Perry's death

Nearly a year later, the mystery surrounding actor Matthew Perry's death was pulled back when federal prosecutors announced criminal charges against five people including a doctor, alleged dealer, assistant and another person linked to his death.

Perry, 54, was found unresponsive and floating face-down in his jacuzzi on Oct. 28, according to an autopsy report from the Los Angeles County medical examiner. His cause of death was listed as "the acute effects of ketamine," with contributing factors including drowning, coronary artery disease, and the presence of buprenorphine, a medication used to treat opioid addiction.

Ketamine, a Schedule III hallucinogen, has been used more recently in clinical and therapeutical settings but can also be ingested recreationally. It was at the center of a monthslong investigation involving the U.S. Drug Enforcement Agency into Perry's death.

On Aug. 15, federal prosecutors announced two arrests, two guilty pleas and a plea agreement in the case.

"Ketamine is a controlled substance. It has some legitimate uses but it is also used illegally," U.S. Attorney for the Central District of California Martin Estrada told reporters during a news conference announcing the charges.

"It can cause serious health effects, serious health problems including loss of consciousness, including spikes in blood pressure and respiratory issues that can deprive the brain of oxygen," Estrada said. "For that reason, it is a drug that must be administered by medical professionals and the patient must be monitored closely."

"That did not occur here," he said.

What is ketamine? 

The DEA lists ketamine as a hallucinogen. It is referred to as a "dissociative anesthetic hallucinogen" because it creates a feeling of detachment from pain and the environment.

Ketamine got its start as an anesthesia medicine for animals in the 1960s. The FDA approved it as an anesthetic for humans in 1970, according to WebMD. 

Angelique Campen, an emergency room doctor of at Providence St. Joseph Medical Center, explains how the drug led to the actor's death. 

"This was probably the perfect storm of combinations that may have led to his death," Campen said. "We use ketamine frequently in the emergency department as an anesthetic because of its safety profile. There are now uses of ketamine for depression given in clinics. Typically it doesn't stop your breathing like opioids and other anesthetics would. ... It has an excellent safety profile, of course with any drug it needs to be given under medical supervision especially an anesthetic."

However, Campen says the drug can be "very dangerous" when used recreationally.

Commonly known by the street names "special K" or "vitamin K," the drug can be both injected or used in its powder form, in which case it is snorted, smoked, or mixed into drinks. 

Effects of the drug

Ketamine can cause what doctors call a "dissociative experience" and what recreational users call a "trip," traditionally lasting about two hours, according to WebMD.

Campen says that this is likely what happened to Perry, causing him to slip into a "trance state" while he was in the water. 

"What I foresee happened with him is, what it does is put you in kind of a trance state, so he probably was in the hot tub in a trance state, slipped under the water and drowned," she said. "So, the ketamine in and of itself doesn't stop your breathing, but it can keep you from waking up if you are submerged."

Recently, ketamine has been used more widely due to its clinical treatment for some cases of major depression. Harvard Health reported that if a person responds to ketamine treatments, it can rapidly reduce suicidal thoughts and can be effective for treating depression combined with anxiety.

Campen suggests that Perry likely took the wrong dosage of ketamine before getting into the pool. 

"Ketamine is not used outside of the supervision of a medical professional. So, if it were in his system at those doses, because it has a very short half life ... it would have been out of his system within 2 to 3 hours," she said, suggesting his use was recreational. 

Ketamine IV infusions are only administered in the doctor's office. They are limited and timed, with most treatments lasting six weeks. WebMD reports the IV infusion lasts about 40 minutes, with the dissociative experience kicking in immediately and lasting for about 15 minutes after the drip ends.

"I think this is an isolated, outlying incident. We see plenty of people that use ketamine and lots of other drugs that are good drugs that we use in a hospital," Campen said, noting that it can be abused during recreational use but that "doesn't take away from the safety profile of it in a hospital, under medical supervision."