A systematic review of drug absorption following bariatric surgery and its theoretical implications (original) (raw)
Related papers
Medication Management after Bariatric Surgery: Providing Optimal Patient Care
Journal of Clinical Medicine, 2020
Substantially altered gastrointestinal anatomy/physiology after bariatric surgery presents new challenges for the proper medication management of these patients; drug absorption and bioavailability may increase, decrease, or remain unchanged post surgery, depending on the specific drug in question and the type of bariatric procedure. In this article, we offer a concise overview of the various aspects of this clinically significant issue, aiming to provide readers with a clear understanding as well as practical tools to handle drug management post bariatric surgery. Realizing the potentially altered pharmacokinetics of various drugs after bariatric surgery is essential for providing optimal pharmacological therapy and overall patient care.
Obesity Reviews
Anatomical changes in the gastrointestinal tract and subsequent weight loss may influence drug disposition and thus drug dosing following bariatric surgery. This review systematically examines the effects of bariatric surgery on drug pharmacokinetics, focusing especially on the mechanisms involved in restricting oral bioavailability. Studies with a longitudinal before-after design investigating the pharmacokinetics of at least one drug were reviewed. The need for dose adjustment following bariatric surgery was examined, as well as the potential for extrapolation to other drugs subjected to coinciding pharmacokinetic mechanisms. A total of 22 original articles and 32 different drugs were assessed. The majority of available data is based on Roux-en-Y gastric bypass (RYGBP) (18 of 22 studies), and hence, the overall interpretation is more or less limited to RYGBP. In the case of the majority of studied drugs, an increased absorption rate was observed early after RYGBP. The effect on systemic exposure allows for a low degree of extrapolation, including between drugs subjected to the same major metabolic and transporter pathways. On the basis of current understanding, predicting the pharmacokinetic change for a specific drug following RYGBP is challenging. Close monitoring of each individual drug is therefore recommended in the early postsurgical phase. Future studies should focus on the long-term effects of bariatric surgery on drug disposition, and they should also aim to disentangle the effects of the surgery itself and the subsequent weight loss.
Improved Levothyroxine Pharmacokinetics After Bariatric Surgery
Background: The absorption of levothyroxine (LT4) is affected by many factors. Bariatric surgery is recommended in severely obese patients. The aim of this study was to determine the consequences of bariatric surgery on LT4 pharmacokinetic parameters, and to identify the regions of the gastrointestinal tract where LT4 is absorbed in patients with severe obesity before and after surgery. Methods: We studied 32 severely obese nonhypothyroid patients who underwent sleeve gastrectomy (SG; n = 10), Roux-en-Y gastric bypass (RYGBP; n = 7), or biliopancreatic diversion with long limbs (BPD-LL; n = 15). Before surgery, from 8:00 a.m., blood samples were collected before and every 30 minutes after the oral administration of a solution of 600 lg of LT4. The same procedure was repeated 35 days after surgery. We estimated the pharmacokinetic parameters of LT4 before and after surgery, including the area under the curve (AUC), the peak thyroxine concentration (C max), and the time to peak thyroxine concentration (T max). Results: Following surgery, in the SG group, the mean AUC was higher than it was before surgery (18.97 – 6.01 vs. 25.048 – 6.47 [lg/dL]$h; p < 0.01), whereas the values of C max and T max were similar to those before surgery. In the RYGBP group, mean AUC, C max , and T max were similar before and after surgery. In the BPD-LL group, mean AUC and C max were higher after surgery than before (14.18 – 5.64 vs. 25.51 – 9.1 [lg/dL]$h, p < 0.001; 5.62 – 1.34 vs. 8.16 – 2.57 lg/dL, p < 0.001, respectively), whereas T max was similar. Conclusions: The pharmacokinetic parameters of LT4 absorption are improved following SG and BPD-LL types of bariatric procedures. We conclude that the stomach, the duodenum, and the upper part of the jejunum are not sites for LT4 absorption, because in the above-mentioned bariatric procedures these are bypassed or removed.
Prescribing challenges following bariatric surgery
Journal of Prescribing Practice
Obesity is an increasing problem in the UK, with over half of the population being overweight or obese. The use of gastric surgery is increasing, with a 5% increase in 2016/17 compared to 2015/16. However, little is known about ideal drug formulations after bariatric surgery. An exploratory literature search of research databases was carried out to address this. The authors found that there was a dearth of high-quality primary studies available, with many studies using low numbers of participants. The major finding was of the need for increased vigilance and monitoring of patients after surgery.
Drug absorption from the small intestine in immediate postoperative patients
British Journal of Anaesthesia, 2006
Background. The effects of surgery on gastric emptying have been documented for a considerable time, but less is known about the effects in the small intestine. It is thought that there is minimal diminution in the absorptive capacity of the small intestine after operation, although there is no literature on drug absorption in the early period after surgery. This study investigated drug absorption from the small bowel in patients undergoing abdominal surgery. Methods. A prospective study of patients undergoing major abdominal surgery in which patients acted as their own preoperative controls was carried out. Patients were administered the test substances, acetaminophen and 99m TcDTPA, before operation and 2 days after operation. Small intestine transit times, plasma concentrations and other pharmacokinetic variables were compared using Student's paired t-test. Two complementary studies were carried out to establish pharmacokinetic parameters. Results. There were no significant differences in the pre-and postoperative values of t max , area under the curve, and area under the moment curve (AUMC) before and after operation (P>0.05). There were significant differences between the pre-and postoperative values of C max [C max (preop) >C max (postop) ; P<0.05] and the pre-and postoperative values of mean residence time (MRT) [MRT (preop) <MRT (postop) ; P<0.01]. Conclusions. Drug absorption from the small bowel in the postoperative patient does not differ significantly from its preoperative absorptive capacity.
Medication Use Following Bariatric Surgery: Factors Associated with Early Discontinuation
Obesity Surgery, 2013
Background-Medication discontinuation is a common result of bariatric surgery. The influence of individual patient characteristics and surgical outcomes on overall and specific medication discontinuation is not well understood. The purpose of the current study was to assess changes in medication use and identify individual characteristics and surgical outcomes associated with medication discontinuation among bariatric patients. Methods-The patients included in the current study received bariatric surgery from the Northern Colorado Surgical Associates of Fort Collins, Colorado between October 2007 and September 2010. Demographic, weight, health, and medication data from 400 patients with at least one 6 or 12 month post-operative appointment were extracted from the Bariatric Outcome Longitudinal Database (BOLD). Multivariate regression analyses were used to investigate how patient factors affect total medication use over time, use of medications grouped by co-morbidity postoperatively, and use of specific medication classes post-operatively. Results-Baseline co-morbidities, particularly type 2 diabetes (T2DM), male sex, and Roux-en-Y gastric bypass surgery were significantly associated with decreased total medication use following surgery. Weight loss, systemic disease, sex, baseline co-morbidities, surgical complications, and race were significantly associated with continued use of specific medications following surgery. Conclusions-Bariatric surgery can help patients with certain characteristics discontinue medications, but is not effective for all patients. Baseline health, sex, race, bariatric procedure, surgical complications, and post-operative weight loss may affect how bariatric patients' medication use changes pre-operatively to post-operatively.