Pharmacokinetics of gallium maltolate after intragastric administration in adult horses.

OBJECTIVE: To determine the pharmacokinetics of gallium maltolate (GaM) after intragastric administration in adult horses. ANIMALS: 6 adult horses. PROCEDURES: Feed was withheld for 12 hours prior to intragastric administration of GaM (20 mg/kg). A single dose of GaM was administered to each horse via a nasogastric tube (time 0). Blood samples were collected at various time points from 0 to 120 hours. Serum was used to determine gallium concentrations by use of inductively coupled plasma-mass spectroscopy. Noncompartmental and compartmental analyses of serum gallium concentrations were performed. Pharmacokinetic models were selected on the basis of the Akaike information criterion and visual analysis of plots of residuals. RESULTS: Serum concentration data for 1 horse were such that this horse was considered an outlier and excluded from noncompartmental and compartmental analyses. Noncompartmental analysis was used to determine individual pharmacokinetic parameters. A 1-compartment model with first-order input and output and lag time was selected as the best-fit model for the data and used to determine mean ± SD values for maximum observed serum concentration (0.28 ± 0.09 µg/mL), time of maximum concentration (3.09 ± 0.43 hours), time to the first measurable concentration (0.26 ± 0.11 hours), apparent elimination half-life (48.82 ± 5.63 hours), area under the time-concentration curve (20.68 ± 757 h•µg/mL), and apparent volume of distribution (73,493 ± 18,899 mL/kg). CONCLUSION AND CLINICAL RELEVANCE: Further studies are necessary to determine the bioavailability of GaM after intragastric administration in adult horses.