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Now here’s one of those structures that you don’t see very often in a drug molecule. It wasn’t intended to be a drug, though – it’s a photolabel tool compound based on the general anesthetic mephobarbital, which is what that trifluoromethyldiazirine group is doing in there. (When those are exposed to light, nitrogen gas takes off, leaving behind a reactive carbene that generally attacks something nearby as quickly as possible).
But when the two enantiomers were tested, it turns out that one of them is about as potent as the best compounds in its class, while the other (the R enantiomer) is ten-fold better. And when used for its intended purpose, as a photolabeling agent, it does show up stuck to specific sites on human GABA receptors, as hoped. So this should provide some interesting information about barbituate binding, although I sort of doubt if anyone’s going to try to develop it into a general anesthetic all on its own.
In a related topic, note that the model for this series, mephobarbital itself, is disappearing from the market. It’s one of those ancient compounds that never really went through the modern regulatory process, but the FDA has stated that it’s not going to let it be grandfathered in. Its manufacturer, Lundbeck, said earlier this year (PDF) that it saw no path forward other than a completely new NDA filing, which didn’t seem feasible, so it was abandoning the product. Existing stocks have expired by now, so mephobarbital is no more, at least in the US.
Derek Lowe is a medicinal chemist with over 20 years experience in the drug industry. He blogs daily on science and drug discovery at In The Pipeline
2012-07-26 02:29:07 Source: http://pipeline.corante.com/archives/2012/07/25/a_diazirine_that_will_knock_you_out.php