<p> <list list-type="bullet"> <list-item> <p>Meldonium inhibits endogenous carnitine synthesis and tissue uptake, and accelerates urinary carnitine excretion, although the impact of meldonium‐mediated muscle carnitine depletion on whole‐body fuel selection, and muscle fuel metabolism and its molecular regulation is under‐investigated.</p> </list-item> <list-item> <p>Ten days of oral meldonium administration did not impact on food or fluid intake, physical activity levels or body weight gain in the rat, whereas it depleted muscle carnitine content (all moieties), increased whole‐body carbohydrate oxidation and muscle and liver glycogen utilization, and reduced whole‐body fat oxidation.</p> </list-item> <list-item> <p>Meldonium reduced carnitine transporter protein expression across muscles of different contractile and metabolic phenotypes. A TaqMan PCR low‐density array card approach revealed the abundance of 189 mRNAs regulating fuel selection was altered in soleus muscle by meldonium, highlighting the modulation of discrete cellular functions and metabolic pathways.</p> </list-item> <list-item> <p> These novel findings strongly support the premise that muscle carnitine availability is a primary regulator of fuel selection <italic>in vivo</italic> . </p> </list-item> </list> </p>