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

The research seeks clarity on the effectiveness of omeprazole in suppressing gastric acidity in horses, by studying the impact of two dosage levels and two diet types.

Objective and Plan of the Study

• The main goal of the study was to analyze the variable duration of intraday acid suppression in horses, when treated with two given doses of omeprazole under separate dietary conditions.
• The study employed a four-way crossover design and used six adult Thoroughbred horses as subjects.
• Over a period of six days, the intragastric pH of the horses was measured for continuous 23-hour periods, with base data gathered on the first day and omeprazole administered on the subsequent five days.

Variables Studied

• This research aimed to evaluate the effect of different doses (1 mg/kg and 4 mg/kg bwt per oral dose) and two types of diets (high grain/low fiber [HG/LF] and ad libitum hay [HAY]) on intragastric pH levels in horses.
• Percentage time when pH was above 4 and the median intraday pH was examined and analyzed for these different conditions using generalised estimating equations.

Observations and Results

• Both the diet and dosage of omeprazole showed noticeable impact on pH levels.
• Higher pH levels were typically recorded with the higher dosage and the HG/LF diet.
• The capability of omeprazole to increase intragastric pH was observed to be efficient under HG/LF dietary conditions but significantly less effective under the HAY diet.
• The research also noted an interesting cumulative effect of dosing on pH levels, a factor not reported in horse studies before.

Conclusions

• The overall effectiveness of omeprazole in increasing gastric pH was found to be lesser than previously believed.
• The study concludes that both omeprazole dosage and dietary type play a significant role in how effectively the drug works in horses.
• The observations recommend against applying singular dosage guidelines universally across diverse types and conditions of horses. Rather, it suggests that tailoring dosage recommendations to the specific diet of the horse might yield more favorable and effective results.