Evaluation of Prophylactic and Therapeutic Effects of Silymarin on Phenobarbital-Induced Hepatotoxicity in Cats

Background: phenobarbital is one of the most commonly used drugs to treat epilepsy and other seizure disorders in dogs and cats. hepatotoxicity following phenobarbital administration is dose-dependent. objectives: the present study aimed to evaluate the protective action of silymarin on phenobarbital-induced hepatotoxicity in cats. methods: for this purpose, twenty-four healthy adult cats were randomly allotted to four equal groups. cats in group a were given phenobarbital with dosage 16 mg/kg orally for 28 days; group b received silymarin (30 mg/kg/day for twenty-eight days) orally concurrent with phenobarbital; groups c and d were treated like group b, but silymarin was administered 3 and 48 h after administration of phenobarbital, respectively, and continued up to twenty-eight days. the serum concentrations of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, total and direct bilirubin, blood urea nitrogen and creatinine were measured before administration of phenobarbital and after 24 h, 72 h and 28 days. results: phenobarbital elevated significantly serum concentrations of liver enzymes (in all cases), and total and direct bilirubin in two cats of group a, after 24 h (p <0.001). in groups, b and c, levels of serum enzyme activities and total and direct bilirubin remained within the normal range up to 28 days (p>0.05), while in group d, levels of serum enzyme activities (in 4 cases) were higher than the normal values (p<0.001). conclusions: the results showed that silymarin can protect liver tissue against oxidative stress in cats with phenobarbital intoxication especially in the first 3 h post-exposure.