Influence of an acidic beverage (Coca-Cola) on the pharmacokinetics of phenytoin in healthy rabbits.

This study was carried out to evaluate the influence of an acidic beverage (Coca-Cola) on the pharmacokinetics of phenytoin in rabbits. In a cross-over study, phenytoin was given orally at a dose of 30 mg/kg and blood samples were taken at different intervals from 0-24 h. After a washout period of 7 days, Coca-Cola (5 ml/kg) was administered in combination with phenytoin (30 mg/kg) and blood samples were taken at various time intervals from 0-24 h. The same rabbits continued to receive Coca-Cola (5 ml/kg) for another 7 days. On the 8th day, Coca-Cola (5 ml/kg) in combination with phenytoin (30 mg/kg) was administered and blood samples were taken at similar intervals. Plasma was separated and assayed for phenytoin by high performance liquid chromatography (HPLC) and various pharmacokinetic parameters were calculated. It was concluded that an acidic beverage (Coca-Cola) increases the extent of absorption of phenytoin by significantly increasing the Cmax and AUC(o-á) of phenytoin. These results warrant the reduction of phenytoin dose when administered in combination with Coca-Cola to avoid any toxicity.