Compounding Study: Know What You're Getting

A recently published study showed that administration of one type of compounded omeprazole suspension was ineffective in healing ulcers in racehorses, while treatment with the FDA-approved form of omeprazole (GastroGard) was effective in attenuating ulcers. The study was completed at the University of California, Davis, and appeared in the latest issue of the Journal of the American Veterinary Association (  Findings show that horse owners trying to save money by using the particular compound used in the study aren't helping their horses, and should spur horse owners to find out what's in compounded medications they purchase. 



Endoscopic views of the same horse exhibiting severe stomach ulcers at pre-trial examination (left), significant healing after 30 days of treatment with GastroGard (center), and the recurrence of ulcers after treatment was switched to compounded omeprazole for an additional 30 days (right).

Jack Snyder, DVM, PhD, chief of equine surgery and lameness at the University of California, Davis, and his research team that included Jorge E. Nieto, MVZ, Dipl. ACVS, title author on the study, scoped 44 Thoroughbreds in training at Golden Gate Fields in San Francisco, Calif. Of the 44, the researchers chose the 32 horses which had the highest degree of ulceration (greater than Grade 2 on a scale of 1-3, with 3 being the most severe) and divided that group in half to establish research groups. The researchers were careful to make sure that the horses showed equal ulceration in the double-blinded study. The horses trained and raced through the duration of the study—none of the horses were pulled or removed from training.

Group one received the recommended dose (4 mg/kg orally) of the GastroGard omeprazole paste once a day, while the other group received a compounded omeprazole suspension at the same dose orally with a dose syringe.

“We treated the horses for 30 days and then scoped them and evaluated their ulcers,” explained Snyder. “Basically, on Day 30 there was a significant difference (improvement) in the ulcer score from Day 0 in those horses that got treated with GastroGard.” There was not a significant difference in the ulcer score at Day 30 for horses receiving the compounded suspension.

“Then we switched groups,” he explained, “meaning the group that got GastroGard (previously) got compounded omeprazole, and the group that got compounded omeprazole received GastroGard. The horses treated with the compound first, then the GastroGard, experienced a significant decrease in the ulcers on Day 60.

“The horses that had started off with GastroGard and then switched to the suspension, their ulcer score was significantly lower at 60 days compared to the baseline, Day 0, but was not (statistically) significantly different from Day 30 in that group. Maybe the suspension held the ulcers at bay, but it didn’t make them better or worse,” he explained.


Group 1
Ulcer scores among horses in Group 1 were dramatically reduced after 30 days of treatment with the FDA-approved formulation of omeprazole (GastroGard). When treatment was switched to compounded omeprazole, the ulcer score showed no statistically significant change.

Group 2
Ulcer scores among horses in Group 2 were virtually unchanged after 30 days of treatment with compounded omeprazole. Subsequent treatment with the FDA-approved formulation of omeprazole resulted in significant healing.

Finally, the researchers looked at four healthy horses without ulcers. They measured the levels of omeprazole in the blood after giving a dose of each drug to see how much omeprazole was absorbed.

“Significantly more omeprazole was getting absorbed from the GastroGard than from the suspension,” he said. Snyder explained that the compounded omeprazole might have been broken down before reaching the small intestine (where it absorbs into the bloodstream), while GastroGard paste was formulated to protect the omeprazole from the acidity of the stomach. UC Davis researchers found that the pH of the suspension was acidic (pH of 3.4), while the GastroGard was basic (pH of 8.4), so Snyder suggested that potentially the already acidic nature of the suspension had eaten away at the omeprazole in the suspension.

“The bottom line is as a horse owner or a veterinarian, you need to know what you’re getting,” said Snyder. “The compounded omeprazole was not as good as the GastroGard. It’s a lot less expensive, but it’s not working, and you might be wasting your time and money.

“The labels (on compounded drugs) are going to tell you what’s in the product and concentration (of the active ingredient),” he said. “Whatever the label says, ask yourself if that’s what you’re truly getting. If there’s enough variability within these compounds, it would be of concern for a veterinarian and horse owner that no matter what drug they’re using, it has the right amount of the active product.”

But Snyder stressed that there is some variation between various compounding pharmacies, and there might be some out there that have a formulation that does better than the one used in the study. “I’d have to go through and do the study on every agent that was out there to know the efficacy of each product,” he said.

Snyder and Merial declined to identify the pharmacy from which the compounded suspension was procured.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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