Flavin Adenin Dinucleotide is a redox cofactor, more specifically a prosthetic group of a protein, involved in several important enzymatic reactions in metabolism. Poly(Flavin Adenin Dinucleotide, FAD) characterized by an additional polymer-type redox reaction is a highly effective electrocatalyst for NADH oxidation: operating at the lowest potentials reported for NADH transducers (0.00 V, pH 7.4), poly(FAD) is characterized by the electrochemical rate constant of 1.8 ± 0.6×10-3 cm/s, which is at the level of the NADH mass-transfer constant. Poly(FAD)-modified electrodes are characterized by the dramatically improved stability and, is the most advantageous NADH transducers for analytical chemistry. Flavin Adenin Dinucleotide (2 mg/kg, i.v.) significantly cancels chlorpromazine (CPZ)-induced decrease in ventricular fibrillation threshold (VFT). Flavin Adenin Dinucleotide cancels the effect of CPZ on canine heart mitochondria. After injection of Flavin Adenin Dinucleotide, the dogs show a transient hypotension within 10 min, then their blood pressures recover to the initial level. Flavin Adenin Dinucleotide also prevents mitochondrial dysfunction induced by chlorpromazine.