<prompt> An example of covalent drug receptor interaction:Noradrenaline binding to β1 adrenergic receptorAcetylcholine binding to muscarinic receptorPrazosin binding to α1 adrenergic receptorPhenoxybenzamine binding to alpha adrenergic receptor  <response>: Phenoxybenamine is an irreversible covalent antagonist at alpha receptors. All other drugs mentioned are reversibly interacting with their receptors. 