Effects of intramuscular omeprazole on gastric acid secretion in horses over a twenty‐four hour period

Sandin, Anders; Andrews, Frank M.; Nadeau, Jenifer; Doherty, Thomas J; Nilsson, Göran

doi:10.1111/j.2042-3306.1999.tb05169.x

Cited by 16 publications

(14 citation statements)

References 6 publications

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“…; Sandin et al . ). In initial studies, omeprazole, as an enteric coated granule formulation, significantly inhibited TAO, but did not increase gastric juice pH, 5 h after the first dose was administered via nasogastric tube.…”

Section: Introductionmentioning

confidence: 97%

Gastric juicepHmeasurement in horses: Three‐quarters of a century of history!

Andrews

2015

Equine Veterinary Education

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Summary Inhibition of gastric acid and increased stomach pH>4.0 is currently accepted as the mainstay of treatment for gastric ulcers in horses. Measurement of gastric pH is complicated and requires placement of a cannula and collection of gastric juice or placement of pH electrodes in the stomach. Since the distance from the nares to the stomach is approximately 200 cm, finding a system with a pH electrode with this length is difficult, not to mention difficult to maintain. There has been a fascination with the measurement of gastric juice pH in horses that has covered three‐quarters of a century starting with a fistula model in 1933 and culminating in a recent technique described in this issue. Placement of gastric cannulas and various pH electrodes have been used to measure gastric juice pH in horses in the past and present, but the future may require more sophisticated methods as we look at the efficacy of different formulations of acid suppressive drugs for treatment of equine gastric ulcer syndrome.

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Section: Introductionmentioning

confidence: 97%

Gastric juicepHmeasurement in horses: Three‐quarters of a century of history!

Andrews

2015

Equine Veterinary Education

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“…These medications, however, have not been subjected to either controlled efficacy tests or extensive field trials. Recently, the leading human compound, omeprazole, has been specifically formulated and extensively tested in horses, leading to recognition of its safety and efficacy by registration with the FDA and publication of relevant developmental studies Daurio et al 1999;Haven et al 1999;MacAllister et al 1999;Murray et al 1999;Plue et al 1999;Sandin et al 1999;Vatistas et al 1999a,b).…”

Section: Introductionmentioning

confidence: 99%

Field survey of the prevalence of gastric ulcers in Thoroughbred racehorses and on response to treatment of affected horses with omeprazole paste

Johnson¹,

Vatistas

Castro³

et al. 2001

Equine Veterinary Education

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“…Early work in the 1990s evaluating the efficacy of different formulations of omeprazole in the horse was primarily performed using a gastric cannulation model [3,4,75,78,84] which was considered the model of choice at the time [85]. An advantage of this method was that it allows the measurement of gastric fluid pH, electrolytes and prostaglandins and the calculation of total daily gastric acid output.…”

Section: Models Of Intra-gastric Ph Measurement In the Horsementioning

confidence: 99%

“…The pharmacokinetics of intravenous omeprazole have been described [74], as has intramuscular administration [75]. The pharmacokinetics following intravenous administration have been described as fitting a two-compartment model with a short β-halflife (t 1/2 ) of 30 minutes [75] (compared with approximately 1 hour in humans and dogs [76]).…”

Section: Pharmacokinetics Of Omeprazole In the Horsementioning

confidence: 99%

“…The pharmacokinetics following intravenous administration have been described as fitting a two-compartment model with a short β-halflife (t 1/2 ) of 30 minutes [75] (compared with approximately 1 hour in humans and dogs [76]). Intramuscular administration has a bioavailability (F%) of 70-80% and a t 1/2 of 45-60 minutes [75]. Despite its widespread use, surprisingly little is published on the pharmacokinetics of oral omeprazole and the factors that potentially influence the pharmacokinetics such as formulation, dose and diet are poorly investigated.…”

Section: Pharmacokinetics Of Omeprazole In the Horsementioning

confidence: 99%

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Factors affecting the pharmacokinetics and pharmacodynamics of omeprazole in the horse

Sykes¹

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Equine Gastric Ulcer Syndrome (EGUS) is a common condition of the horse, affecting a broad range of horse usages and types. Recently the terminology of the syndrome has been expanded to include terms Equine Squamous Gastric Disease (ESGD) and Equine Glandular Gastric Disease (EGGD) to describe diseases of the squamous and glandular mucosa of the stomach, respectively. Omeprazole, a proton pump inhibitor that blocks acid production, is considered the treatment of choice for EGUS and it has been widely used for this purpose for nearly 20 years. Yet, surprisingly, despite its widespread use little is known about the factors that affect its efficacy, such as the impact of formulation, diet and dose. Further, although it is commonly believed that the once daily administration of omeprazole results in durations of acid suppression exceeding 24 hours, there is conflict in the literature as to the validity of this belief. Recent clinical studies have demonstrated that the healing rate for EGGD is inferior to that of ESGD, raising further questions as to the efficacy of omeprazole under clinically relevant conditions. One potential reason for this observation is that the duration of intra-day acid suppression required for healing of ESGD may be less than that for EGGD. This, coupled with the possibility that once daily administration of omeprazole may not result in acid suppression for the entire 24 hour treatment interval, provides a potential explanation for the poor EGGD healing rates that have been recently reported. The purpose of this thesis was to investigate the factors that affect the efficacy of omeprazole in the horse. The studies were conducted in four parts; firstly, the effect of formulation and diet on the pharmacokinetics of omeprazole were investigated; secondly, a model that allows continuous intra-gastric pH measurement under clinically relevant conditions was developed; thirdly, the impact of diet and dose on the pharmacokinetics and pharmacodynamics of omeprazole were investigated; and lastly, the relationships between key pharmacokinetic and pharmacodynamic variables were investigated. The findings of the study suggested that some method of physical protection is required to protect the omeprazole from degradation in the acidic environment of the stomach and to improve bioavailability. However, significant differences were not present between formulations utilising the two most common forms of protection, namely the use of enteric coated granules in paste or buffering of the formulation. This suggests that the method of protection, buffering of the formulation or the use enteric coated granules in paste, used is less important than protection per se. The earlier studies of the thesis 3 suggested that an effect of feeding may be present on the pharmacokinetics of omeprazole but a statistically significant effect could not be demonstrated. Similarly, the latter studies suggested that diet may play a role in bioavailability with ad libitum roughage diets impairing absorption, but no statistically signi...

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Effects of intramuscular omeprazole on gastric acid secretion in horses over a twenty‐four hour period

Cited by 16 publications

References 6 publications

Gastric juicepHmeasurement in horses: Three‐quarters of a century of history!

Gastric juicepHmeasurement in horses: Three‐quarters of a century of history!

Field survey of the prevalence of gastric ulcers in Thoroughbred racehorses and on response to treatment of affected horses with omeprazole paste

Factors affecting the pharmacokinetics and pharmacodynamics of omeprazole in the horse

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