Pharmacokinetics of gallium nitrate after oral administration in adult horses \u2013 pilot study

Gallium (Ga), a metal in group IIIA of the periodic table, has shown a remarkable activity against bone resorption and could therefore possibly prove useful in the treatment of certain diseases in sport horses, for example navicular disease. The aim of this study was to gain more information concerning the kinetics of Ga after oral administration of gallium nitrate (GaN) in adult horses. Six horses received a single dose of 10 mg\u2044 kg of GaN mixed with the food ration. Absorption was slow (Tmax = 10 \ub1 3 h, T\ubdabs = 2 \ub1 0.8 h), and a Cmax of 26 \ub1 11 lg \u2044 L was achieved. Excretion followed a one-phase elimination model, with a long half-life (T\ubdel = 52 \ub1 14 h). By means of a mathematical model, we estimated that the plasmatic levels should reach 93 lg \u2044 L (1.33 lM) at steady state, following the repeated daily administration of 10 mg\u2044 kg of GaN. A three times lower concentration has been demonstrated as effective in inhibiting the osteolytic activity of osteoclasts in vitro. The results of this study suggest that the administration of oral GaN at a rate of 10 mg\u2044 kg per day may be considered for future clinical studies