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What is Ibutilide and explain in detail?
Ibutilide is a Class III antiarrhythmic agent that is indicated for acute cardioconversion of atrial fibrillation and atrial flutter of a recent onset to sinus rhythm. It exerts its antiarrhythmic effect by induction of slow inward sodium current, which prolongs action potential and refractory period (physiology) of myocardial cells. Because of its Class III antiarrhythmic activity, there should not be concomitant administration of Class Ia and Class III agents.
Ibutilide is marketed as Corvert by Pfizer. Administration resulted in successful heart rhythm control in 31-44% of patients within 90 minutes, with sustained polymorphic ventricular tachycardia in 0.9-2.5% of patients. It appears to show better results in atrial flutter as compared to atrial fibrillation.

Mechanism of action
Ibutilide, like other class III antiarrhythmic drugs, blocks delayed rectified potassium current.It does have action on the slow sodium channel and promotes the influx of sodium through these slow channels.
Although potassium current seems to play a role, their interactions are complex and not well understood. Ibutilides unique mechanism works by an activation of a specific inward sodium current, thus producing its therapeutic response in which a prolonged action potential increases myocytes’ cardiac refractoriness in case of atrial fibrillation and flutter.

Pharmacokinetics
Absorption
Ibutilide is intravenously administered. It has a high first-pass metabolism, which results in a poor bioavailability when taken orally. Individual pharmacokinetic properties are highly viable during the clinical trial.

Distribution
Ibutilide has a relatively large volume of distribution among individual subjects, which is about 11L/kg. Approximately 40% of the drug is bound with plasma albumin of healthy volunteers in a trial. This is also approximately close to patients with atrial fibrillation and flutter.

Metabolism
Ibutilide has a high systemic plasma clearance that closes to the hepatic blood flow  (29mL/min/kg)