Omeprazole and weight changes
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Omeprazole and Body Weight Changes: Animal Study Insights
Several animal studies have examined the effects of omeprazole on body weight. In chickens, omeprazole treatment led to reduced body weight gain, even though it increased the size of the parathyroid glands and affected bone density. This effect was not seen with food restriction or vitamin D alone, suggesting a specific impact of omeprazole, likely related to increased gastrin levels caused by the drug . Similarly, in young male rats, long-term omeprazole treatment suppressed body weight gain and reduced bone mineralization, although fat and lean body mass proportions remained unchanged . In mice, the effect of omeprazole on weight gain was found to depend on sex and genetic background. Some male mice on a high-calorie diet with omeprazole gained significantly more weight, while other strains and females did not show this effect, highlighting the importance of genetic and sex differences . Another mouse study found that long-term omeprazole administration led to reduced weight gain, which may be linked to increased inflammation markers in the blood .
Omeprazole and Weight in Humans: Obesity and Pharmacokinetics
Research on humans has focused more on how obesity affects omeprazole’s pharmacokinetics rather than direct weight changes. Obese individuals have lower clearance of omeprazole, meaning the drug stays in their system longer, which could increase the risk of side effects if standard doses are used for long-term treatment . After weight loss surgery (Roux-en-Y gastric bypass), the bioavailability of omeprazole is reduced, but six months after surgery, drug levels return to those seen in people who have not had surgery, suggesting no need for dose adjustment in the long term . Another study using modeling confirmed that obesity reduces the activity of enzymes that break down omeprazole, but this is restored after gastric bypass surgery . The route of omeprazole administration (intravenous vs. continuous infusion) in obese patients after sleeve gastrectomy did not affect overall drug exposure, but continuous infusion led to better control of stomach acidity and shorter duration of gastrointestinal symptoms .
Mechanisms Behind Omeprazole’s Impact on Weight
The animal studies suggest that omeprazole’s effect on weight may be linked to its impact on hormone levels, such as gastrin, and possibly on inflammation and oxidative stress 124. In mice, changes in gut microbiota and energy expenditure were also observed, which could contribute to differences in weight gain depending on genetic background and sex . In humans, while direct evidence of omeprazole causing weight gain or loss is lacking, changes in drug metabolism in obese individuals could potentially influence side effects or efficacy, but not necessarily body weight itself 568.
Conclusion
Animal studies consistently show that omeprazole can suppress weight gain, especially in young or growing animals, and this effect may be influenced by sex, genetic background, and inflammation. In humans, current research does not directly link omeprazole to weight changes, but highlights that obesity alters how the body processes the drug. After weight loss surgery, omeprazole’s pharmacokinetics normalize over time. Overall, while omeprazole may affect weight in animals, there is no strong evidence for significant weight changes in humans due to omeprazole use alone.
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