Introduction
Antazoline is a drug used in the treatment of atrial fibrillation (AF), and its formula is C17H19N3. In fact, the cornerstone of AF therapy is a long-term antithrombotic treatment followed by adequate rhythm or rate control. The pharmacological cardioversion of AF to sinus rhythm (SR) can be achieved by the administration of class IA, IC, and III antiarrhythmic drugs or vernakalant hydrochloride. However, the treatment may be related to potential pro-arrythmia, lack of efficacy or the exceptionally high cost of a compound used. Fortunately, antazoline could help handle the trouble.
Pharmacologic action
Antazoline can competitively block the H1 receptor in effector cells, reducing the effects of histamine release in tissues, such as the increase of capillary permeability and telangiectasia, and some degree of smooth muscle contraction. In addition, like most H1 receptor antagonists, antazoline can affect the activity of central nervous system. It also has mild local anesthesia and anticholinergic effect. The effects on the central nervous system vary with dose and vary significantly among individuals. Sedation may occur when the therapeutic dose is given, but it may change to excitatory effect when the concentration of active substances is high.
Clinical efficacy
Antazoline is a first generation antihistaminic agent with chinidine-like and anticholinergic properties. When administered intravenously, antazoline exerts a strong antiarrhythmic effect on supraventricular arrhythmia, especially on AF, facilitating rapid conversion to SR. Antazoline prolongs action potential duration and lowers its amplitude, prolongs phase 0 duration, reduces phase 4 of resting potential and reduces excitability of cardiac tissue. Clinically, antazoline lowers the velocity of intraatrial conduction, prolongs the atrial refraction period and may improve atrioventricular conduction allowing fast ventricular response to supraventricular arrhythmias. The half-life of antazoline is considered to be about three hours with antiarrhythmic efficacy expiring after about one hour.
Pharmacokinetics and metabolism
Oral administration took effect for 30min, intravenous administration took effect for 15min, and the efficacy lasted 4-6h. Antazoline is metabolized in the liver and excreted by the kidneys.
References:
Farkowski, M. M., Maciag, A., Dabrowski, R., Pytkowski, M., Kowalik, I., & Szwed, H. (2012). Clinical efficacy of antazoline in rapid cardioversion of paroxysmal atrial fibrillation--a protocol of a single center, randomized, double-blind, placebo-controlled study (the AnPAF Study). Trials, 13(1), 162.
Kline, S. R., Dreifus, L. S., Watanabe, Y., McGarry, T. F., & Likoff, W. (1962). Evaluation of the antiarrhythmic properties of antazoline: A preliminary study. American Journal of Cardiology, 9(4), 564-567.
