<prompt> Potassium Channel Openers are following exceptPinacidilDiazoxideNicorandilAmiodarone  <response>: Ans, d Amiodarone Ref. KDT 6th534Drugs acting on potassium channelPotassium channel openersPotassium channel blockersAmiodarone blocks myocardial delayed rectifier KchannelsOldNovel MinoxidilNicorandilQ DiazoxidePinacidil0Cromakalim Antiarrhythmics-- K channel blockers class III - Amiodarone. Ibutilide, Dofetilide, Sotalol. MECHANISM: AP duration, ERP. Used when other antiarrhythmics fail. QT interval. C1INICA1 uSE: Atrial fibrillation, atrial flutter; ventricular tachycardia amiodarone, sotalol. TOXICITY: Sotalol--torsades de pointes, excessive a blockade. Ibutilide--torsades de pointes. Amiodarone--pulmonary fibrosis, hepatotoxicity, hypothyroidism hyperthyroidism amiodarone is 40 iodine by weight, corneal deposits, skin deposits bluegray resulting in photodermatitis, neurologic effects, constipation, cardiovascular effects bradycardia, heart block, CHF.Certain drugs modulate opening and closing of the channels, e.g. Quinidineblocks myocardial Na channels. Dofetilide amiodaroneblock myocardial delayed rectifier K channel. Nifedipineblocks L-type of voltage sensitive Ca2channel. Nicorandilopens ATP-sensitive K channels. Sulfonylureasinhibit pancreatic ATP-sensitive K channels. Amilorideinhibits renal epithelial Na channels. Phenytoinmodulates prolongs the inacti vated state of voltage sensitive neuronal Na channel. Ethosuximideinhibits T-type of Ca2 channels in thalamic neurones 