Adrenergic antagonists, or sympatholytics, bind to adrenoceptors to prevent receptor activation by catecholamines or other agonists. They can be classified as ɑ or β adrenergic blockers based on their affinities for adrenoceptors. α-blockers bind to the ɑ1 and ɑ2 subtypes. They are either nonselective or selective, based on their specificity. Nonselective α-blockers, such as phenoxybenzamine and phentolamine], contain haloalkylamine and imidazoline moieties, respectively. Selective α1-blockers feature quinazoline and piperazine rings along with an acyl group. The optimal activity of these compounds depends on the 4-amino group and the nature of the acyl group, which yields prazosin and its analogs. Selective α2-blockers, such as yohimbine, belong to the indole alkylamines category. In conclusion, the α-blockers exhibit structural diversity and bear little resemblance to their agonist counterparts. Nevertheless, they effectively antagonize the actions of agonists on the adrenoceptors.