Meldonium

Etki Mekanizması

Meldonium exerts its primary pharmacological effect by inhibiting gamma-butyrobetaine hydroxylase (BBOX), the enzyme responsible for the final step in the biosynthesis of L-carnitine from gamma-butyrobetaine (GBB). By competitively blocking this enzyme, meldonium reduces endogenous carnitine production, which in turn lowers intracellular carnitine concentrations over time. Since carnitine is essential for the transport of long-chain fatty acids across the inner mitochondrial membrane via the carnitine palmitoyltransferase (CPT) system, reduced carnitine levels impair fatty acid beta-oxidation. This forces cells -- particularly cardiomyocytes and skeletal muscle cells -- to shift their metabolic fuel preference from fatty acid oxidation toward glucose oxidation. This metabolic shift is the cornerstone of meldonium's cardioprotective mechanism. Under ischemic conditions (reduced blood flow), fatty acid oxidation becomes metabolically inefficient and even harmful: incomplete fatty acid oxidation generates toxic intermediates (long-chain acylcarnitines and acyl-CoA species) that damage cell membranes and impair mitochondrial function. Glucose oxidation, by contrast, requires less oxygen per molecule of ATP produced and does not generate these toxic intermediates. By forcing the heart to rely more on glucose, meldonium effectively optimizes energy production under oxygen-limited conditions and reduces the accumulation of cardiotoxic lipid metabolites. Additionally, the accumulation of GBB that results from BBOX inhibition has been shown to stimulate nitric oxide (NO) production via an ester-mediated mechanism, promoting vasodilation, improving endothelial function, and reducing peripheral vascular resistance. Meldonium also upregulates the expression of glucose transporter proteins (GLUT-1 and GLUT-4) and activates components of the Akt-dependent cardioprotective signaling pathway, further enhancing myocardial resistance to ischemic injury.