Trimetazidine

During myocardial ischemia, anaerobic metabolism takes over, increasing levels of lactic acid. The decreased intracellular pH and increased concentration of protons activates sodium-hydrogen and sodium-calcium antiport systems, raising intracellular calcium concentrations, finally leading to decreased contractility.

This injury to the myocardium raises concentrations of catecholamines, which activate hormone sensitive lipase, and increasing fatty acid concentrations in plasma. When the myocardium is repurfused, fatty acid oxidation becomes the dominant form of ATP production, maintaining an acidic pH, and further exacerbating the injury.

The mechanism of action of trimetazidine is not fully understood. Trimetazidine may inhibit mitochondrial 3-ketoacyl coenzyme A thiolase, decreasing long chain fatty acid β-oxidation but not glycolysis in the myocardium. The decreased long chain fatty acid β-oxidation is compensated for by increased use of glucose, preventing a lowered myocardial pH, and further decreases in contractility. However, another study suggests that 3-ketoacyl coenzyme A thiolase may not be trimetazidine's target, and that this mechanism may be incorrect.