Potassium Channel Openers are following except

Ans, d (Amiodarone) (Ref. KDT 6th/534)Drugs acting on potassium channelPotassium channel openersPotassium channel blockersAmiodarone (blocks myocardial delayed rectifier K+channels)OldNovel 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 (blue/gray) 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 Ca2+channel.# 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