The effects of dose and diet on the pharmacodynamics of esomeprazole in the horse.

This research investigates the varied influence of dosage and diet on the effectiveness of esomeprazole in treating equine gastric ulcer syndrome in horses.

Objective and Methodology

• The main aim of this research was to assess the duration of acid suppression accomplished with two different doses of esomeprazole under two dietary conditions.
• The study was handled as a four-way crossover design involving six Thoroughbreds, all instrumented with percutaneous gastrotomy tubes.
• Throughout six consecutive days, intragastric pH was measured for continuous 23-hour periods. Recording of baseline data was done on Day 0 and administration of esomeprazole on Days 1-5.
• The investigation examined two doses (0.5 and 2.0 mg/kg bwt/day per os once daily) and two diets (a high grain/low fibre (HG/LF) and ad libitum hay (HAY) diet).
• Data analysis was carried out using generalized estimating equations on the percentage of time pH was above 4 (%tpH>4) and median intraday pH.

Findings

• The impact of both diet and dose was inconsistent, with mean %tpH>4 and mean of the median intraday pHs typically higher at the 2.0 mg/kg bwt dose and in HG/LF diet.
• A cumulative effect of dosing was observed, with the intensity of acid suppression observed on Day 5 being consistently higher than that noted on Day 1.
• Importantly, the magnitude of acid suppression, at measurement point 1, aligned favorably with previous reports on omeprazole and exceeded human therapeutic breakpoints for the 0.5 mg/kg bwt dose in the HG/LF diet and 2.0 mg/kg bwt dose in the HAY diet.

Conclusion and Future Work

• Instrumentation for the study might have altered gastric function, and horses were neither fasted nor exercised which is important to mention as a limitation.
• Results indicate that both dose and diet impact the response to esomeprazole in horses, and a cumulative effect is observed over the initial 5 days of treatment.
• The authors conclude that additional research into the clinical effectiveness of esomeprazole is required, along with trials comparing esomeprazole and omeprazole directly.