Propofol (Milk of Amnesia)

Anaesthetics are weird. Much of what we use has a paucity of the oxygens and nitrogens that seems to make most drugs work, and there's been substantial puzzlement and handwringing over exactly how some of these things work. Xenon, for example, is a fine anaesthetic that is, of course, comprised of a single atom. Similarly, highly halogenated molecules that are otherwise uninteresting are common.

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Propofol is used in an IV emulsion (an intimate, homogeneous mixture of water and oil, like ranch dressing, or GOJO). The milky color of the product is the origin of the nickname in the title - "Milk of Amnesia." The method of administration is largely for solubility reasons, but emulsions can do more than solublize stubborn stuff. The benign, dull melatonin you take for jet lag, when administered at high doses in an emulsion, can actually act as a much more profound anaesthetic than its health food store origins would suggest.

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Isn't it a good antioxidant as well? It looks like a little bit less hindered version of BHT which you can still find in some sunscreen lotions in Europe...

The reason propofol comes as an emulsion is that it's mostly lipid, which is true of most drugs which get into the brain. The following is from a post of mine Paul put on ChemBark

Few of the drugs first used to treat neurological disease were discovered rationally. The first drug for epilepsy (bromide ion) was thought to work by decreasing libido, as epileptics were thought to be sexually overwrought. Things improved in the 30s with the discovery that seizures could be induced by electric shocks administered to the brain. Zillions of hapless rabbits were shocked while pumped full of various drugs. If the drug increased the current required for seizures, it was a potential anticonvulsant. This is exactly how Dilantin was discovered. Cruel, but at least rational.

Science marches on, and it was soon discovered that drugs getting into the brain (which is mostly fat) had to be soluble in lipids (which meant they weren't too soluble in water). So potential drugs were first put into amphipathic (soluble in water and lipids) solvents, like soap. Soap is basically a bunch of long chain (12-18 carbons) carboxylic acids. One such solvent was 2-propylpentanoic acid (valproic acid). Many drugs put into it seemed to work pretty well. Fortunately, someone had the brains to do a control, and found that the actual anticonvulsant was valproic acid (and a very useful one it was -- although like everything else in medicine, not without side effects). A case of not throwing out the bathwater. Anything similar in chemistry?

Retread

PS -- Interesting that you teach at Bryn Mawr (which is where my wife is from). Hopefully the inmates remain as interesting and intelligent as they were back then.