Evaluation of prophylactic and therapeutic effects of silymarin and N-acetylcysteine in acetaminophen-induced hepatotoxicity in cats.

Cats most commonly receive toxic amounts of acetaminophen (APAP) because owners medicate them without consulting a veterinarian. The aim of this study was to compare the hepatoprotective action of silymarin and N-acetylcysteine (NAC) against APAP poisoning. Twenty healthy cats were randomly allotted to five equal groups. Animals in group A were given APAP (single dose 150 mg/kg, p.o.); groups B and C consisted of cats that received NAC (100 mg/kg, p.o.) or silymarin (30 mg/kg, p.o.) concurrent with APAP administration respectively; groups D and E were treated like groups B and C, respectively, but 4 h after APAP administration. The serum concentrations of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), methemoglobin, and total and direct bilirubin were measured before APAP administration and 4, 24, and 72 h later. A single oral administration of APAP significantly elevated serum concentrations of ALT, AST, ALP, LDH, methemoglobin, and total and direct bilirubin. In both the groups receiving APAP plus NAC or silymarin, levels of serum enzyme activities, methemoglobin, and total and direct bilirubin remained within the normal values. It was concluded that silymarin as well as NAC can protect liver tissue against oxidative stress in cats with an APAP intoxication.