ABSTRACT 

This work aimed at evaluating the chronic effect of therapeutic dose of acetaminophen and ameliorative effects of antioxidant vitamins in wistar albino rats. A total of 56 male Wistar rats with body weights range 70 – 100 g used in this study were fed Vital growers mash and water ad libitum, and grouped into 7 (n=8). Group 1 was fed Vital growers mash and water ad libitum while groups 2 and 3 received only acetaminophen at 1500 mg and 1000 mg per 70 kg body weight, respectively. Groups 4 and 5 were administered acetaminophen at 1500 mg and 1000 mg per 70 kg body weight with concomitant administration of vitamin C at a dose of 100 mg/kg body weight, while groups 6 and 7 were administered acetaminophen at 1500 mg and 1000 mg per 70 kg body weight respectively, together with vitamin E 1000 iµ/70 kg body weight. These administrations were done for weeks 1, 3, 5 and 7 while nothing was administered on the 2^nd, 4^th and 6^th week during which the animals were fed only feed and water ­ad libitum. At the end of each administration week, two animals selected randomly from each group were anaesthetized using chloroform and blood samples collected via cardiac puncture. The blood samples for biochemical assays were respectively collected in anticoagulant-free tubes and allowed to clot before centrifugation. The sera were separated thereafter and used for the assays, while the blood samples for haematological parameters were collected in EDTA-containing sample bottles and used for the tests. These assays and tests were carried out using standard methods. Results show that in the 7^th week, the groups administered 1500 and 1000 mg/70 kg BW paracetamol, had a significant (p<0.05) increase in activity of the determined liver marker enzymes: aspartate aminotransferase, alanine amino transferase and alkaline phosphatase. The exposure also caused a significant (p<0.05) increase in concentration of the determined kidney function parameter (urea) as well as total protein. A significant (p<0.05) increase was also observed in activities of the determined serum antioxidants (superoxide dismutase, catalase), as well as in the concentration of malondialdehyde. The haematological parameters of the untreated animals showed significant (p<0.05) decrease in results of all parameters at the 5^th and 7^th week. The altered results showed a significant (p<0.05) increase in the treated groups when compared with the control. These significant (p<0.05) decreases were observed when groups 4, 5, 6 and 7 (administered with varying doses of paracetamol and antioxidant vitamins C and E) were compared with group 1 as well as groups 2 and 3. Serum urea concentration was also significantly (p<0.05) decreased in the groups administered acetaminophen only at the varying doses; these alterations were also significantly (p<0.05) corrected in the groups co-administered antioxidant vitamins. Histopathological examinations seemingly corroborated the serum chemistry. Thus, the therapeutic dose of acetaminophen when taken over time can lead to depletion of serum antioxidants, increase in generation of toxic compounds and finally, damage to some vital biological organs. Hence, co-administration of antioxidant vitamins will ameliorate the observed effects of long term consumption of acetaminophen.