Efficacy of Omeprazole Powder Paste or Enteric‐Coated Formulation in Healing of Gastric Ulcers in Horses

Background GastroGard, an omeprazole powder paste formulation, is considered the standard treatment for gastric ulcers in horses and is highly effective. Gastrozol, an enteric‐coated omeprazole formulation for horses, has recently become available, but efficacy data are controversial and sparse. Objectives To investigate the efficacy of GastroGard and Gastrozol at labeled doses (4 and 1 mg of omeprazole per kg bwt, respectively, PO q24h) in healing of gastric ulcers. Animals 40 horses; 9.5 ± 4.6 years; 491 ± 135 kg. Methods Prospective, randomized, blinded study. Horses with an ulcer score ≥1 (Equine Gastric Ulcer Council) were randomly divided into 2 groups and treated for 2 weeks each with GastroGard followed by Gastrozol (A) or vice versa (B). After 2 and 4 weeks, scoring was repeated and compared with baseline. Plasma omeprazole concentrations were measured on the first day of treatment after administration of GastroGard (n  =  5) or Gastrozol (n = 5). Results Compared with baseline (squamous score (A) 1.65 ± 0.11, (B) 1.98 ± 0.11), ulcer scores at 2 weeks ((A) 0.89 ± 0.11, (B) 1.01 ± 0.11) and 4 weeks ((A) 1.10 ± 0.12, (B) 0.80 ± 0.12) had significantly decreased in both groups ( P  < .001), independent of treatment ( P  = .7). Plasma omeprazole concentrations were significantly higher after GastroGard compared with Gastrozol administration (AUC GG  = 2856 (1405‐4576) ng/ mL  × h, AUC GZ  = 604 (430‐1609) ng/ mL  × h; P  = .03). The bioavailability for Gastrozol was 1.26 (95% CI 0.56–2.81) times higher than for GastroGard. Conclusions and Clinical Importance Both Gastrozol and GastroGard, combined with appropriate environmental changes, promote healing of gastric ulcers in horses. However, despite enteric coating of Gastrozol, plasma omeprazole concentrations after single labeled doses were significantly higher with GastroGard.