Background: Acetaminophen, a widely used analgesic and antipyretic is known to cause hepatic injury in humans and experimental animals when administered in high doses. It was reported that toxic effects of acetaminophen are due to oxidative reactions that take place during its metabolism. L-carnitine is a cofactor in the transfer of long-chain fatty acid allowing to the beta-oxidation of fatty acid in the mitochondria. It is a known antioxidant with protective effects against lipid peroxidation. This study aimed to investigate the possible beneficial effect of L-carnitine as an antioxidant agent against acetaminophen induced hepatic toxicity in rats.
Material and Methods: Four rat groups (N=7 in each group). Group I is the control, group II received 500 mg/kg/ body weight of L-carnitine for 7 days by oral route, group III received 640/kg/ bw of acetaminophen by oral route, group IV acute acetaminophen group pretreated with L-carnitine for 7 days by gastric tube gavage tube. The liver of all rats were removed for investigation using light and electro microscopic studies.
 Results: Acetaminophen caused massive centrilobular necrosis and massive degenerative changes. The electron-microscopic study showed few mitochondria, increased fat droplets and scanty smooth endoplasmic reticulum (SER), rough endoplasmic reticulum (RER).These changes were reduced by L-carnitine pretreatment.
 Conclusion: those results suggest that acetaminophen results damage in the liver as an acute effect and L-carnitine ameliorated the adverse effects of acetaminophen via its antioxidant role.