Vitamin B12 Supplementation: Effects On Some Biochemical And Haematological Indices Of Rats On Phenytoin Administration

Phenytoin is known to have some toxicological implications. Vitamin B₁₂ supplementation during phenytoin administration was investigated to assess the benefits and risks of single vitamin supplementation. This study evaluated the biochemical and haematological effects of vitamin B₁₂ on phenytoin toxicity. Twenty-four experimental animals were divided into 3 groups of 8 rats each. The control (group 1) received distilled water as placebo. Groups 2 and 3 were given 5mg/kg body weight of phenytoin for 4 weeks while group 3 in addition to phenytoin received intra-peritoneal administration of 15μg/kg body of vitamin B₁₂ twice a week. Biochemical parameters such as AST, ALT, ALP, lipid profile and haematological indices were assayed as indices of toxicity. The result of the study showed that phenytoin administration resulted in anaemia which was ameliorated by vitamin B₁₂ co-administration. Phenytoin also increased significantly the leukocyte count upon which B₁₂ had no effect. Liver enzymes activities were significantly (p<0.05) raised during phenytoin administration and interestingly B₁₂ further increased the level of these enzymes. Administration of phenytoin only gave a significant (p<0.05) increase in the level of serum Low density lipoprotein cholesterol. Serum cholesterol, TG and HDL-chol were not significantly affected. Although there was no significant change in serum cholesterol, the slight increase was more than 1% which is capable of causing a 3% increase in the risk of coronary heart disease. A significant decrease was also noted when phenytoin was supplemented with B₁₂. We observed that vitamin B₁₂ co-administration is beneficial in remitting anaemia and the atherosclerotic risk caused by phenytoin but may enhance hepatotoxicity. By this result we would therefore suggest that the use of vitamin B₁₂ alone as supplement during phenytoin administration be discouraged.

Keywords
Phenytoin, serum enzymes, lipid profile, vitamin B12, atherosclerosis, hepatotoxicity