Amiodarone HCl

Amiodarone possesses an inhibitory effect on the fast sodium channel as well as on the slow calcium channel. Amiodarone also has non-competitive antisympathetic effects, and modulates thyroid function and phospholipid metabolism. Amiodarone penetrates deeply into the lipid matrix of the membrane, and is released from cardiac tissues very slowly when washed out. Amiodarone (44–88 μM) depresses Vmax of guinea pig papillary muscle without affecting the resting membrane potential, and that this Vmax inhibition is enhanced in a frequency- or use-dependent manner like Class I antiarrhythmic drugs. Amiodarone (50–88 μM) is also found to suppress the depolarization-induced spontaneous action potentials (abnormal automaticity) in ventricular muscles and in Purkinje fibers. ^[1]

Amiodarone (1.25–25 mg/kg) results in a decrease in sinus rate, a prolongation of effective and functional refractory periods of the atrioventricular node, and a frequency-dependent conduction delay in the atrioventricular node and in the ventricle of anesthetized dogs. Amiodarone (50 mg/kg/day, i.p. for 3–4 weeks) results in significant decreases in the current density of iK and ito in ventricular cells without affecting iCa and iK1 densities in rabbit. Amiodarone (AM) inhibits intracellular conversion from thyroxine (T4) to triiodothyronine (T3) via 5′-deiodination (5′DI) without affecting intracellular conversion from T4 to reverse T3 (rT3). ^[1]