Comparative Oral Absorption of Different Citicoline and Homotaurine Formulations: A Single-Dose, Two-Period Crossover Trial in the Dog

Background: Citicoline and homotaurine are compounds with a potent neuroprotective activity and they have been administered for many years in the treatment of numerous neurodegenerative and ophthalmological diseases, including glaucoma. Initially available only as liquid form, through parenteral route, nowadays citicoline can be administered also as tablet but no data on bioavailability of these different forms are available. In the present study, pharmacokinetics of citicoline in tablet versus vials, each at the therapeutic dose of 500 mg, in addition to 50 mg of homotaurine was investigated. Materials and methods: Ten mixed breed dogs received a single dose of 50 mg oral homotaurine and 500 mg citicoline in tablet and vials with the same dose were administered after a seven days wash-out period. Parameters assessed for citicoline metabolites (cytidine, uridine and choline) were AUC0−t, Cmax and Tmax. Results: Citicoline bioavailability appeared to be higher for the tablet compared to the vial formulation. Cytidine is equivalent in absorption dynamics both for tablet and liquid form; uridine for tablet reaches its maximum and is reabsorbed more quickly while choline for the liquid form reaches the maximum first and is reabsorbed more quickly. Conclusions: Citicoline in tablet and liquid formulation have pharmacokinetic properties leading to a very similar bioavailability.