Effect of omeprazole paste on gastric acid secretion in horses

Abstract

Summary In a multicentre trial, 13 cannulated horses were treated orally once daily with a paste that delivered omeprazole at a dose of 4 and 5 mg/kg bwt in a 2‐period crossover design to evaluate steady state gastric acid suppression. In each period, basal (unstimulated) and pentagastrin‐stimulated gastric output were evaluated at 5–8 h after 5 doses, at 13–16 h after 10 doses, and at 21–24 h after 15 doses. Baseline data for gastric acid secretion were collected once for each horse in the month prior to initiation of omeprazole treatment. The inhibition of gastric acid secretion relative to baseline values, following treatment with omeprazole, were calculated and expressed as per cent. Pharmacokinetic data were also collected in this trial. At 4 mg/kg bwt, the oral paste formulation of omeprazole inhibited both basal and pentagastrin‐stimulated gastric acid secretion by 99% at 5–8 h after treatment and by 83% (basal) and 90% (pentagastrin‐stimulated) at 21–24 h. Inhibition following the administration of omeprazole at a dose of 5 mg/kg bwt was not significantly greater than when given at 4 mg/kg bwt. The results from this study could possibly lead to the development of an effective and practical antisecretory treatment of ulcer disease in horses.

Effects of two intravenous dose levels of omeprazole on the gastric juice pH of healthy horses

“…This is consistent with some reports of minimal inter-individual variability in baseline gastric pH (Tellez et al, 2005;Andrews et al, 2006). Nevertheless, other studies have reported significant inter-horse variations (Daurio et al, 1999;JD Ruiz et al, 2012).…”

“…In the present study, pH remained above 4 for up to 11 hours after injection of either 1 or 2 mg/Kg omeprazole; which is the minimum pH that should be maintained for as long as possible in order to improve the healing rate of gastric lesions (Armstrong, 2004). However, only the highest omeprazole dose in our study (2 mg/Kg) was able to maintain the pH above 4 for 24 h after injection in every horse treated; which is similar to results reported by other researchers using 4 mg/Kg orally (Daurio et al, 1999). Our results clearly indicate that a single dosage of 2 mg/ Kg IV omeprazole inhibits gastric acid secretion for 24 hours.…”

“…Omeprazole blocks H+ secretion from parietal cell membranes by irreversibly joining the H+, K+ ATPase proton pump (Holt and Howden, 1991). Pharmaceutical preparations for oral administration of omeprazole range from tablets to enteric-coated granules developed to release the drug in the intestine, thus preventing it from being degraded by the acidic environment of the stomach (Daurio et al, 1999;Ruiz JD et al, 2012). Oral administration of 4 mg/Kg omeprazole once daily is highly effective for healing gastric ulcers in horses (Doucet et al, 2003;McClure et al, 2005;McKeever et al, 2006;Sykes et al, 2014).…”

“…Anti-ulcer treatments generally consist in neutralizing stomach acidity using antacids or to reduce acid secretion with antisecretory drugs, aiming to provide a favorable environment for healing. Proton-pump inhibitors such as omeprazole are commonly used to suppress gastric acid secretion (Daurio et al, 1999;Ruiz JD et al, 2012). Histamine-2 (H2) antagonists such as ranitidine or cimetidine (Campbell-Thompson and Merritt, 1987) are also commonly used for this purpose.…”

Association Between Nonsteroidal Anti-Inflammatory Drugs and Gastric Ulceration in Horses and Ponies

“…However, the authors of the current chapter believe it is important to report their study with omeprazole, a drug that binds irreversibly to the H + , K + -ATPase enzyme of gastric parietal cells (which secrete hydrogen ions into the stomach in exchange for K + ions), thereby inhibiting the production of chloridric acid. Omeprazole also selectively inhibits carbonic anhydrase, which adds to its acid suppressive properties (Daurio et al, 1999;MacAllister, 1999). Although this drug is considered the most effective inhibitor of gastric secretions (90% in 24 hour at 4 mg/kg bwt daily), it has a low bioavailability after oral intake (14-16%) (Andrews et al, 1992;Téllez et al, 2005).…”