[An experimental study on hepatotoxicity of topiramate in young rats]

Topiramate (TPM) has an evident efficacy in the treatment of childhood epilepsy for multiple pharmacologic properties. However it was reported that it may cause adverse effects such as liver failure and hepatitis, which arouses the attention of the medical field. This study aimed to investigate the hepatotoxicity of low-dosage, high-dosage TPM or TPM along with valproate sodium (VPA) in aspects of biochemistry indexes, oxidative stress indexes and liver pathomorphology in young rats.

Sixty 3-week-old male Wistar rats were randomly assigned into five groups of 12 rats (Groups A-E). The rats in the experimental groups (Groups A-C) were administered intragastrically with TPM 40 mg/(kg.d), 80 mg/(kg.d) and TPM 40 mg/(kg.d) plus VPA 300 mg/(kg.d) respectively. The rats in the negative control group (Group D) were administered with the same volume of distilled water. The ones in the positive control group (Group E) were treated by injection of 10% carbon tetrachloride dissolved in olive oil subcutaneously at a dose of 5 mL/kg twice a week. After 3-month administration, the changes of body weight and liver pathomorphology were observed; biochemical markers in serum and indexes of oxidative stress in liver homogenate associated with hepatotoxicity were examined.

The body weights of rats in the experimental groups were significantly lower than that of rats in the negative control group. The levels of serum alanine aminotransferase, alkaline phosphatase and the content of malondialdehyde, and the activity of superoxide dismutase in liver tissues did not change significantly in the experimental groups. The contents of glutathion in the high dosage of TPM group (29.85 +/- 1.62 mg/g prot) or in the TPM plus VPA group (29.63 +/- 4.47 mg/g prot) were significantly reduced compared with those of the negative control group (33.09 +/- 1.69 mg/g prot) and that of the low dosage of TPM group (32.43 +/- 2.11 mg/g prot) (both P < 0.05). In the histopathological examination, extensive steatosis and diffuse punctate necrosis of hepatocytes distributed in the portal area were found by microscopy in the positive control group. There were granular degeneration of some hepatocytes near the central veins of hepatic lobules in the low dosage of TPM group and punctate necrosis of some hepatocytes in the high dosage of TPM group. In the TPM plus VPA group, histological examination showed granular degeneration and fatty degeneration of partial liver cells and punctate necrosis of some hepatocytes.

Long-term use of TPM can decrease antioxidant capacity of organism, resulting in slight pathological changes of liver tissues. High dosage of TPM or TPM along with VPA administration enhances the risk of the side effects.