These data were produced from a study that assessed mitochondrial metabolic function by measuring two metabolites, l-carnitine and acetylcarnitine, to determine their effectiveness as candidate clinical biomarkers for age-related, drug-induced alterations in mitochondrial metabolism. To study age and medication-related changes in mitochondrial metabolism, we administered the FDA-approved mitochondriotropic drug, clofazimine (CFZ), or vehicle for to young and old mice. These findings are described in our manuscript: Clofazimine-Mediated, Age-Related Changes in Skeletal Muscle Mitochondrial Metabolites. Data reported was supported by funding from the National Institute of General Medical Sciences (NIGMS) at the National Institutes of Health (NIH) under award numbers R01GM127787 (GRR), R35GM136312 (KAS), P30AR069620 (K Jepsen), and T32GM140223 (L Isom).