The crystal structure of LSD bound in its active state to a serotonin receptor , specifically the 5-HT 2B receptor, has recently (2017) been elucidated for the first time.    The LSD-bound 5-HT 2B receptor is regarded as an excellent model system for the 5-HT 2A receptor and the structure of the LSD-bound 5-HT 2B receptor was used in the study as a template to determine the structural features necessary for the activity of LSD at the 5-HT 2A receptor.    The diethylamide moiety of LSD was found to be a key component for its activity, which is in accordance with the fact that the related lysergamide lysergic acid amide (LSA) is far less hallucinogenic in comparison.  LSD was found to stay bound to both the 5-HT 2A and 5-HT 2B receptors for an exceptionally long amount of time, which may be responsible for its long duration of action in spite of its relatively short terminal half-life.    The extracellular loop 2 leucine 209 residue of the 5-HT2B receptor forms a 'lid' over LSD that appears to trap it in the receptor, and this was implicated in the potency and functional selectivity of LSD and its very slow dissociation rate from the 5-HT 2 receptors.   
This application note describes the extraction of benzodiazepine compounds from whole blood, prior to GC/MS analysis. This protocol also allows the simultaneous extraction of various other drugs of abuse classes: amphetamines, barbiturates, cocaine and opiates.
ISOLUTE® SLE+ columns with 1 mL sample capacity are used to extract whole blood samples following a straightforward sample dilution. No protein precipitation or other pre-treatment is required prior to sample loading. The sample preparation procedure delivers clean extracts, good recoveries and RSD values and LLOQs from 10 ng/mL (analyte dependant).
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