Fluparoxan (GR50360A) is a potent α2-adrenergic receptor antagonist (pKB = 7.9) with excellent α2/α1 selectivity (2630 fold), and is the only well-studied a2 antagonist in its structural family which does not antagonize any variant of the imidazoline receptor.It was shown to possess central α2-adrenoceptor antagonist activity after oral doses in man and was patented as an antidepressant by Glaxo in the early 1980s, but its development was discontinued when the compound failed to show a clear clinical advantage over existing therapies.