The milky anaesthetic behind most surgery was invented by a vet
Propofol looks like milk because it is suspended in soybean oil and lecithin. John B. Glen, a British veterinary anaesthesiologist at ICI, first made it in 1973. It now dominates the induction of general anaesthesia, having largely displaced sodium thiopental, because patients go under fast and wake quickly with little nausea.
Getting the drug into a usable form was the hard part. The first human formulation used a solvent called Cremophor, which triggered too many severe allergic reactions, so the drug was reworked as a 1 percent emulsion in soybean oil. Sterile emulsions are notoriously tricky to make, their stability depending on factors such as droplet size. Propofol reached patients in the UK and New Zealand in 1986, won FDA approval in October 1989 under the brand Diprivan, and sits on the WHO's List of Essential Medicines.
Its range is wide. Beyond putting surgical patients to sleep, it can maintain anaesthesia through computer-controlled infusion pumps, sedate ventilated patients in intensive care, where it beats lorazepam on both results and cost partly because benzodiazepines build up in very sick patients, and calm children through MRI scans. Several guidelines recommend it for seizures that resist standard drugs. For endoscopies it allows faster recovery than midazolam.
The drawbacks are real. Injection often stings, especially in small veins, because the drug activates a pain receptor called TRPA1; lidocaine beforehand or a larger vein helps. It can drop blood pressure by 30 percent or more and frequently stops breathing briefly, sometimes for over a minute. Responses vary so much that small doses can sedate some people profoundly. After several deaths of children sedated in ICUs during the 1990s, the FDA issued a warning. Oddly, it can turn urine green.
Its steep dose-response curve makes misuse dangerous. Some anaesthetists on punishing rotas have abused it for the rested feeling it leaves, and addiction has been reported. Public attention surged in August 2009, when a coroner found that Michael Jackson had died that June from propofol combined with benzodiazepines. European restrictions on exporting it for use in executions mean no one has been put to death with it.
Source: Propofol
