Experimental and Clinical Pharmacokinetics of Fluoxetine and Amitriptyline: Comparative Analysis and Possible Methods of Extrapolation

Pharmacokinetics of fluoxetine in horses following oral administration

“…In the equine stomach, more of the drug may be uncharged and more readily absorbed in this location than in the other species. The elimination half‐life in horses (15.6 ± 5.2 h) was also more rapid than in cats (46.8 ± 6.5 h) and humans (37.6 ± 3.3 days), but comparable to dogs (dogs 18.5 ± 0.4) (Altamura et al, 1994; Ciribassi et al, 2003; Kondratenko et al, 2019). While compounded formulations carry uncertainties, a compounded paste is a feasible option for clients electing to treat their horses with fluoxetine.…”

“…Following oral administration to horses, this compounded formulation of fluoxetine was more rapidly absorbed and eliminated than has been reported in other species. Maximum serum concentration following oral administration was reached within 1.5 h for all horses in the single‐dose study, but required approximately 12, 6, and 6–8 h for cats, dogs, and humans, respectively (Alegete et al, 2014; Kondratenko et al, 2019; Zhang et al, 2010). In the equine stomach, more of the drug may be uncharged and more readily absorbed in this location than in the other species.…”

“…Since fluoxetine absorption is slow in many species (Tmax of 6, 6–8, and 12 h for dogs, humans, and cats, respectively), blood was collected immediately prior to drug administration ( T = 0) and at T = 30, 60, 90, 120, 150, and 180 min, T = 6, 12, 18, 24, 48 h, and T = 7 days following administration by jugular venipuncture into a glass serum separator tube with no clotting activator (Corvac Integrated Serum Separator Tube, 9 ml draw, Covidien; Altamura et al, 1994; Ciribassi et al, 2003; Kondratenko et al, 2019). Blood was stored at 4°C within 30 min of collection.…”