The Effects of Bariatric Surgery and Gastrectomy on the Absorption of Drugs, Vitamins, and Mineral Elements

Abstract

Bariatric surgery, which is an effective treatment for obesity, and gastrectomy, which is the primary treatment method for gastric cancer, alter the anatomy and physiology of the digestive system. Weight loss and changes in the gastrointestinal tract may affect the pharmacokinetic parameters of oral medications. Both bariatric and cancer patients use drugs chronically or temporarily. It is important to know how surgery affects their pharmacokinetics to ensure an effective and safe therapy. The Cochrane, PubMed, and Scopus databases were searched independently by two authors. The search strategy included controlled vocabulary and keywords. Studies show that bariatric surgery and gastrectomy most often reduce the time to maximum plasma concentration (tmax) and decrease the maximum plasma concentration (Cmax) in comparison with the values of these parameters measured in healthy volunteers. Vitamin and mineral deficiencies are also observed. The effect depends on the type of surgery and the properties of the drug. It is recommended to use the drugs that have been tested on these groups of patients as it is possible to monitor them.

Oral Potassium Malabsorption Following Bariatric Surgery

“…The powdered form was more effective because it is absorbed through the lining of the small intestine at a faster rate and bypasses the need for the breakdown of a pill or capsule. A 2021 cross-sectional study found that bariatric surgery reduces the time to maximal plasma concentration (Tmax) and the maximum plasma concentration (Cmax) of most drugs and vitamins [ 6 ]. Therefore, while the small intestine is able to absorb the drug more rapidly, it ultimately absorbs less of it, thus significantly decreasing serum drug concentration [ 6 ].…”

“…A 2021 cross-sectional study found that bariatric surgery reduces the time to maximal plasma concentration (Tmax) and the maximum plasma concentration (Cmax) of most drugs and vitamins [ 6 ]. Therefore, while the small intestine is able to absorb the drug more rapidly, it ultimately absorbs less of it, thus significantly decreasing serum drug concentration [ 6 ]. In our patient’s case, her Cmax for absorption of the oral potassium pill was likely similarly decreased.…”

Controversial Interactions of Tacrolimus with Dietary Supplements, Herbs and Food

“…Furthermore, it has been established that the metabolism of tacrolimus depends on the individual predispositions, such as BMI (body mass index), patient’s age, albumin concentration or hepatic failure [ 1 ]. Tacrolimus is mainly metabolised by the cytochrome P450 (CYP450) isoform CYP3A4, which is involved in the metabolism of a number of substances, such as beverages, alcohol, herbs, medications and food [ 6 ]. Nevertheless, these substances may be the inducers or inhibitors of the abovementioned enzyme.…”

Bariatric surgery and oral chemotherapy: Where is the dosing guidance?

“…Bariatric surgery is an effective weight management strategy that has been demonstrated to improve overall survival, mitigate the effects of cardiovascular and metabolic diseases (including diabetes and hyperlipidemia), and reduce cancer risk and cancer‐related mortality 1,2 . The procedures can be broadly classified as those that are primarily restrictive of the amount of food stored in the stomach but not interfering with normal digestion (e.g., sleeve gastrectomy and gastric banding), those that limit absorption by shortening the gastrointestinal tract (e.g., biliopancreatic diversion), and those that combine both mechanisms (e.g., Roux‐en‐Y gastric bypass) 3 . Thus, depending on the type of procedure, the absorption of medications, including oral chemotherapy agents, may be affected in different ways.…”

“…1,2 The procedures can be broadly classified as those that are primarily restrictive of the amount of food stored in the stomach but not interfering with normal digestion (e.g., sleeve gastrectomy and gastric banding), those that limit absorption by shortening the gastrointestinal tract (e.g., biliopancreatic diversion), and those that combine both mechanisms (e.g., Roux-en-Y gastric bypass). 3 Thus, depending on the type of procedure, the absorption of medications, including oral chemotherapy agents, may be affected in different ways. Bariatric surgery alters gastric mixing and disintegration of food and medications, decreases gastric acid secretion and thus results in an increased pH, accelerates gastric transit time via hormonal and neural influences, changes the enterohepatic recirculation of bile acids in the upper intestine, reduces the functional gastrointestinal tract absorptive area, and alters drug metabolism by bypassing the parts of the small intestine that contain a high abundance of cytochrome P450 isoenzymes.…”