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If you鈥檝e been following the manslaughter trial of Michael Jackson鈥檚 personal physician (not surprisingly, the has had the most complete coverage), today鈥檚 guilty verdict wasn鈥檛 a surprise.

Prosecutors built a strong case that the 50-year-old 鈥渒ing of pop鈥� died after Dr. Conrad Murray had given Jackson a large dose of (pronounced PRO-poe-fall), a powerful anesthetic, to help him sleep and then left him unattended.

Murray鈥檚 defense team spun a theory that Jackson gave himself the lethal dose.

Either way, propofol was at the heart of the case. The Los Angeles County coroner had concluded that Jackson died from 鈥渁cute propofol intoxication鈥� on June 25, 2009, and Murray鈥檚 trial featured lots of testimony about the drug.

Even if propofol isn鈥檛 quite a household word, it鈥檚 a lot more familiar than it used to be.

The 鈥榤ilk of anesthesia鈥�

I wanted to learn a bit more about propofol, so I met with Dr. Linda Aglio, an anesthesiologist at Harvard-affiliated Brigham and Women鈥檚 Hospital in Boston and an associate professor of anesthesiology at Harvard Medical School The hospital鈥檚 anesthesiology department is a warren of offices on the same subterranean level as the operating rooms.

When Dr. Aglio showed me a small bottle of propofol, the 鈥渕ilk of anesthesia鈥� nickname made perfect sense. Propofol doesn鈥檛 dissolve in water so it comes in a white, oily solution and must be refrigerated before it鈥檚 used. The solution consists of soybean oil, fats purified from egg yolks, and glycerol.

occur, although propofol is generally considered safe for people with egg allergies because people are usually allergic to the proteins in eggs, not the fat.

Dr. Aglio explained that the reason most of us haven鈥檛 heard of propofol until the Jackson case is that, aside from abuse cases, propofol is used exclusively by anesthesiologists. It鈥檚 not the kind of drug that you can pick up at CVS or Walgreens, or one that you鈥檙e going to see advertised on television.

Replaced sodium thiopental

But in anesthesiology circles, propofol is a hot item: 鈥淲e鈥檙e using it like crazy,鈥� Dr. Aglio told me.

Propofol is used as an 鈥渋nduction agent鈥濃�攖he drug that causes loss of consciousness鈥� for general anesthesia in major surgery. In lower doses it is also used for 鈥渃onscious sedation鈥� of patients getting procedures on an outpatient basis at ambulatory surgery centers.

The major reason that propofol has become the induction agent of choice is that the traditional agent, a barbiturate called sodium thiopental, is no longer available, Dr. Aglio explained. Sodium thiopental (the old trade name, Sodium Pentothal, might be more familiar) has been one of the drugs used to execute people with lethal injections, and various groups and countries opposed to the death penalty have used legal and other sorts of pressure on suppliers.

For general anesthesia, anesthesiologists use a large 鈥渂olus鈥� of between 100 and 200 milligrams of propofol to put patients under and then a continuous infusion of much smaller amounts (in the micrograms per minute, with the exact amount depending on the person鈥檚 weight) to keep patients under. The drug is infused into a vein, and there鈥檚 often some pain as it goes in, which is why she was reluctant to use it at first, Dr. Aglio said. To prevent that pain, anesthesiologists will often an inject a local anesthetic like lidocaine before the intravenous administration of propofol, she said.

Like many sedating anesthetics, propofol lowers blood pressure and suppresses breathing, so the heart function and breathing of patients need to be constantly monitored. 鈥淚 won鈥檛 leave a patient unattended for a second,鈥� said Dr. Aglio.

When she read about the circumstances of Michael Jackson鈥檚 death, her first reaction was shock: 鈥淚 was surprised that any doctor taking care of him would leave him alone.鈥�

鈥楲ike a switch鈥�

Propofol is also a very good anesthetic for milder sedation used for outpatient surgery because it puts people in a semi-conscious, drowsy state. 鈥淚t has a very quick onset, but also wears off quickly. It鈥檚 like a switch. There鈥檚 little, if any, anesthetic hangover. And it doesn鈥檛 cause nausea or vomiting. And there is some loss of memory, which is a good thing,鈥� explained Dr. Aglio.

Potential for abuse

So there鈥檚 a lot of propofol around these days and, as the Jackson case sadly shows, opportunities exist for abuse, with possibly fatal consequences.

Michael Jackson was apparently desperate to sleep, and there are plenty of people like him who might want to get their hands on propofol so they could use it as a powerful sleep aid.

But a published last year argued persuasively that if propofol were only sedating, without having any other effects, there would be 鈥渓ittle recreational incentive鈥� to abuse it. The authors鈥擟ourtney Wilson, Peter Canning, and E. Martin Caravati, three doctors in the Division of Emergency Medicine at University of Utah鈥攏oted that volunteers in experimental studies have found propofol鈥檚 effects pleasurable and described the sensation as a high or like being drunk. They also cite case reports about propofol giving anesthesia patients good dreams and instances of sexual disinhibition with 鈥渁morous advances and physical embraces by patients who are awakening from propofol anesthesia.鈥� The review also mentions that people develop a tolerance to propofol, so they end up needing more of it to achieve the same sensation. And the fact that it鈥檚 so short-acting might be an advantage for abusers, because they can come off the high quickly, which could make illicit use easier to hide.

Searching the medical literature between 1992 and 2009, the Utah doctors found 45 published cases of propofol abuse鈥�40 of which involved medical professionals鈥攁nd 18 deaths. When academic anesthesiology training programs were surveyed a few years ago, 23 out of 126 (18%) reported that incidents of propofol abuse or diversion had occurred for the 10-year period between 1995 and 2005.

So propofol abuse definitely occurs, but it鈥檚 also not that common鈥攁t least so far. The reviewers鈥� take-away is that propofol should be regulated as a controlled substance like other strong anesthetic drugs; Dr. Aglio agrees.

Whether tighter regulation would have made a difference for Michael Jackson is doubtful; the king of pop had means to get around rules, and enablers like Conrad Murray to help him. But obviously we will never know.