Background:

Lofexidine is a α2-Receptor agonist for opioid detoxification. Lofexidine shows a strong affinity for the α2A-receptor subtype [1].

The α2 adrenergic receptor is a G protein-coupled receptor (GPCR) consisting three highly homologous subtypes, α2A-, α2B-, and α2C-adrenergic. The α-receptors in brain are important presynaptic modulators of central noradrenergic function (autoreceptors) and postsynaptic mediators of many effects of catecholamines and related drugs. The α2-adrenergic agonists can be used as antihypertensives and preanesthetic agents [2].

Lofexidine is extensively absorbed, reaching peak concentrations at approximately 3 hours after oral administration. The mean maximum serum concentrations following a single 1.2 or 2.0 mg dose in healthy male adults were 1755 ± 306 and 2795 ± 593 ng/ml, respectively [1].

Clinical trials: Lofexidine has entered clinical trials in the patients treatment of opiate withdrawal. Lofexidine-treated patients experienced a rebound increase in blood pressure following discontinuation of lofexidine. The most frequently reported adverse events were insomnia, dry mucous membranes, sedation, dizziness, and asthenia [1].

参考文献:
[1] Gish E C, Miller J L, Honey B L, et al.  Lofexidine, an α2-receptor agonist for opioid detoxification[J]. Annals of Pharmacotherapy, 2010, 44(2): 343-351.
[2] Scheinin M, Lomasney J W, Hayden-Hixson D M, et al.  Distribution of α2-adrenergic receptor subtype gene expression in rat brain[J]. Molecular Brain Research, 1994, 21(1): 133-149.