Abstract
The adrenergic compounds are chemical structures related to Adrenaline and Noradrenaline e.g., isoprenaline and terbutaline, when want to change in the chemical structure of adrenergic will lead us to an adrenergic blocking agents e.g., Alpha blockers and Beta blockers (prazosin, terazosin, propranolol and atenolol). Also, cholinergic agents especially direct cholinergics are chemical structures related to Acetylcholine which when manipulate of the Ach. We obtain anti-cholinergic agents like neostigmine, physostigmine, pilocarpine… etc. All the blockers are examples of drug discovery depends on Drug targeting (Alpha receptor, Beta receptor, Muscarinic receptor, Nicotinic receptor).