Evaluation of the diffusion of corticosteroids between the distal interphalangeal joint and navicular bursa in horses

Objective—To determine whether clinically effective concentrations of methylprednisolone or triamcinolone can be achieved in the navicular bursa after injection of methylprednisolone acetate (MPA) or triamcinolone acetonide (TA) into the distal interphalangeal joint (DIPJ) and whether clinically effective concentrations of these drugs can be achieved in the DIPJ after injecting the navicular bursa with the same doses of MPA or TA. Animals—32 healthy horses. Procedures—Horses in groups 1 through 4 received 40 mg of MPA in the DIPJ, 10 mg of TA in the DIPJ, 40 mg of MPA in the navicular bursa, and 10 mg of TA in the navicular bursa, respectively. Concentrations of corticosteroids that diffused into the adjacent synovial structure were determined. Results—For group 1, injection of MPA into the DIPJ yielded a mean ± SD concentration of 0.24 ± 0.072 μg of methylprednisolone/mL in the navicular bursa. For group 2, injection of TA into the DIPJ yielded 0.124 ± 0.075 μg of triamcinolone/mL in the navicular bursa....