Impact of hepatic impairment and renal failure on the pharmacokinetics of linezolid and its metabolites: contribution of hepatic metabolism and renal excretion

Linezolid, an oxazolidinone antibiotic, is used in patients with liver or kidney disease. However, the effects and mechanisms of hepatic impairment or renal failure on the pharmacokinetics of linezolid and its metabolites (PNU-142586 and PNU-142300) remain unclear. We used carbon tetrachloride-induced impaired hepatic function and 5/6 nephrectomy-induced renal failure rat models to investigate linezolid and metabolite pharmacokinetics. Isolated primary rat hepatocytes were used to evaluate the impact of hepatic impairment or renal failure on linezolid metabolism. Uptake and efflux transport studies were also conducted. The influence of hepatic impairment or renal failure on the pharmacokinetics of linezolid and two metabolites did not differ between intragastric gavage and intravenous administration in rats. Linezolid did not accumulate in the brain, heart, lung, liver, kidney, and small intestinal tissues of the hepatic impairment or renal failure rats. And PNU-142300 did not accumulate in the liver or kidney tissue. Compared to the isolated normal rat hepatocytes, the <i>in vitro</i> hepatic clearance of linezolid in hepatic impairment and renal failure rat hepatocytes decreased by 61.3% and 44.1%, respectively. Organic anion transporting polypeptide (OATP)1B1, OATP1B3, OATP2B1, Na+-taurocholate co-transporting polypeptide (NTCP), organic anion transporter (OAT)1, OAT3, multidrug resistance-associated protein 2 (MRP2), or multidrug resistance protein 1 (MDR) did not mediate linezolid transport. Hepatic impairment primarily increases linezolid exposure through reduced hepatic metabolism, whereas renal failure increases both linezolid and two metabolites exposure through reduced hepatic metabolism and renal glomerular filtration. These findings guide adjusting the dose of linezolid in patients with hepatic and renal insufficiency.