The present invention provides aqueous parenteral formulations containing an antiarrhythmic agent, such as amiodarone, and a sulfoalkyl ether cyclodextrin. The liquid formulations are clear, sterilizable, and chemically and physically stable. The liquid formulations do not require a surfactant and do not precipitate upon dilution with distilled water or other pharmaceutically acceptable liquid carrier. The sulfoalkyl ether cyclodextrin-containing formulation provides significant advantages over other cyclodextrin-containing formulations of amiodarone. The formulation can be prepared in acidic, neutral and slightly basic medium while providing acceptable concentrations of amiodarone suitable for parental administration. An SAE-CD-containing formulation of amiodarone can be provided in liquid form or as a reconstitutable powder. Moreover, highly concentrated solutions exceeding 200 mg of amiodarone per mL can be prepared. Solutions can be made either dilutable or non-dilutable with water at room temperature or under conditions typically encountered in the clinic.