Influence of Bariatric Surgery on the Use and Pharmacokinetics of Some Major Drug Classes

Direct Oral Anticoagulants in Special Patient Populations

Anticoagulants are a cornerstone of treatment in atrial fibrillation. Nowadays, direct oral anticoagulants (DOACs) are extensively used for this condition in developed countries. However, DOAC treatment may be inappropriate in certain patient populations, such as: patients with chronic kidney disease in whom DOAC concentrations may be dangerously elevated; frail elderly patients with an increased risk of falls; patients with significant drug-drug interactions (DDI) affecting either DOAC concentration or effect; patients at the extremes of body mass in whom an "abnormal" volume of distribution may result in inappropriate drug concentrations; patients with recurrent stroke reflecting an unusually high thromboembolic tendency; and, lastly, patients who experience major hemorrhage on an anticoagulant and in whom continued anticoagulation is deemed necessary. Herein we provide a fictional case-based approach to review the recommendations for the use of DOACs in these special patient populations.

Suicide attempts after bariatric surgery: comparison to a nonsurgical cohort of individuals with severe obesity

BACKGROUND

The rate of suicide is higher among individuals following bariatric surgery compared with the general population; however, it is not clear whether risk is associated with bariatric surgery beyond having severe obesity.

OBJECTIVE

To compare the risk of a suicide attempt among those who had bariatric surgery versus a nonsurgical cohort with severe obesity.

SETTING

Aggregate count data were collected from 5 healthcare systems.

METHODS

Individuals were identified in the surgical cohort if they underwent bariatric surgery between 2009 and 2017 (n = 35,522) and then were compared with a cohort of individuals with severe obesity who never had bariatric surgery (n = 691,752). Suicide attempts were identified after study enrollment date using International Classification of Diseases, Ninth and Tenth Editions (ICD-9 and ICD-10) diagnosis codes from 2009 to 2021.

RESULTS

The relative risk of a suicide attempt was 64% higher in the cohort with bariatric surgery than that of the nonsurgical cohort (2.2% versus 1.3%; relative risk = 1.64; 95% CI, 1.53-1.76). Within the cohort with bariatric surgery, suicide attempts were more common among the 18- to 39-year age group (P < .001), women (P = .002), Hawaiian-Pacific Islanders (P < .001), those with Medicaid insurance (P < .001), and those with a documented mental health condition at baseline (in the previous 2 years; P < .001).

CONCLUSIONS

The relative risk of suicide attempts was higher among those who underwent bariatric surgery compared with a nonsurgical cohort, though absolute risk remained low. Providers should be aware of this increased risk. Screening for suicide risk after bariatric surgery may be useful to identify high-risk individuals.

The Effects of Bariatric Surgery on Pharmacokinetics of Drugs: a Review of Current Evidence

PURPOSE OF REVIEW

Obesity constitutes a major public health concern and has been recognized as an epidemic. To date, bariatric surgery remains the most effective way for substantial long-lasting weight loss in severe obesity. The purpose of this review is to summarize how the pharmacokinetics of drugs are affected by the most common types of bariatric surgery, i.e., Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG).

RECENT FINDINGS

Limited data are available regarding the changes in pharmacokinetics of drugs after bariatric surgery. The lack of existing guidelines may lead patients to experience drug toxicity or therapeutic undertreatment. Pharmacokinetic parameters that need to be taken into consideration postoperatively include gastric motility, gastric volume, pH, surface area, bile secretions, carrier proteins, and first-pass metabolism. For drugs with a narrow therapeutic index, other factors need to be monitored closely, including plasma drug levels, patients' clinical outcomes, and laboratory markers. Patients should be followed up frequently and treated in accordance with their response to the drug therapy. Bariatric surgery may affect the pharmacokinetics of various drugs, due to the resultant anatomical changes and the substantial weight loss. Therefore, there is a need to identify those potential changes and adjust patients' medication doses in order to achieve higher efficacy and avoid toxicity.

Antiallergic Treatment of Bariatric Patients: Potentially Hampered Solubility/Dissolution and Bioavailability of Loratadine, but Not Desloratadine, Post-Bariatric Surgery

Gastrointestinal anatomical/physiological changes after bariatric surgery influence variables affecting the fate of drugs after ingestion, and medication management of these patients requires a thorough and complex mechanistic analysis. The aim of this research was to study whether loratadine/desloratadine antiallergic treatment of bariatric patients is at risk of being ineffective due to impaired solubility/dissolution. The pH-dependent solubility of loratadine/desloratadine was studied in vitro, as well as ex vivo, in gastric content aspirated from patients before versus after bariatric surgery. Then, a biorelevant dissolution method was developed to simulate the gastric conditions after sleeve gastrectomy (SG) or one-anastomosis gastric bypass (OAGB), accounting for key variables (intragastric volume, pH, and contractility), and the dissolution of loratadine/desloratadine was studied pre- versus post-surgery. Dissolution was also studied after tablet crushing or syrup ingestion, as these actions are recommended after bariatric surgery. Finally, these experimental data were implemented in a newly developed physiologically based pharmacokinetic (PBPK) model to simulate loratadine/desloratadine PK profiles pre- versus post-surgery. For both drugs, pH-dependent solubility was demonstrated, with decreased solubility at higher pH; over the pH range 1-7, loratadine solubility decreased ∼2000-fold, and desloratadine decreased ∼120-fold. Ex vivo solubility in aspirated human gastric fluid pre- versus post-surgery was in good agreement with these in vitro results and revealed that while desloratadine solubility still allows complete dissolution post-surgery, loratadine solubility post-surgery is much lower than the threshold required for the complete dissolution of the drug dose. Indeed, severely hampered loratadine dissolution was revealed, dropping from 100% pre-surgery to only 3 and 1% post-SG and post-OAGB, respectively. Tablet crushing did not increase loratadine dissolution in any post-bariatric condition, nor did loratadine syrup in post-OAGB (pH 7) media, while in post-laparoscopic SG conditions (pH 5), the syrup provided partial improvement of up to 40% dissolution. Desloratadine exhibited quick and complete dissolution across all pre-/post-surgery conditions. PBPK simulations revealed pronounced impaired absorption of loratadine post-surgery, with 84-88% decreased C_max, 28-36% decreased F_a, and 24-31% decreased overall bioavailability, depending on the type of bariatric procedure. Desloratadine absorption remained unchanged post-surgery. We propose that desloratadine should be preferred over loratadine in bariatric patients, and as loratadine is an over-the-counter medication, antiallergic therapy after bariatric surgery requires special attention by patients and clinicians alike. This mechanistic approach that reveals potential post-surgery complexity, and at the same time provides adequate substitutions, may contribute to better pharmacotherapy and overall patient care after bariatric surgery.

Medication Use for Obesity-Related Comorbidities After Sleeve Gastrectomy or Gastric Bypass

IMPORTANCE

Sleeve gastrectomy and gastric bypass are the most common bariatric surgical procedures in the world; however, their long-term medication discontinuation and comorbidity resolution remain unclear.

OBJECTIVE

To compare the incidence of medication discontinuation and restart of diabetes, hypertension, and hyperlipidemia medications up to 5 years after sleeve gastrectomy or gastric bypass.

DESIGN, SETTING, AND PARTICIPANTS

This comparative effectiveness research study of adult Medicare beneficiaries who underwent laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass between January 1, 2012, to December 31, 2018, and had a claim for diabetes, hypertension, or hyperlipidemia medication in the 6 months before surgery with a corresponding diagnosis used instrumental-variable survival analysis to estimate the cumulative incidence of medication discontinuation and restart. Data analyses were performed from February to June 2021.

EXPOSURES

Laparoscopic sleeve gastrectomy and laparoscopic Roux-en-Y gastric bypass.

MAIN OUTCOMES AND MEASURES

The primary outcome was discontinuation of diabetes, hypertension, and hyperlipidemia medication for any reason. Among patients who discontinued medication, the adjusted cumulative incidence of restarting medication was calculated up to 5 years after discontinuation.

RESULTS

Of the 95 405 patients included, 71 348 (74.8%) were women and the mean (SD) age was 56.6 (11.8) years. Gastric bypass compared with sleeve gastrectomy was associated with a slightly higher 5-year cumulative incidence of medication discontinuation among 30 588 patients with diabetes medication use and diagnosis at the time of surgery (74.7% [95% CI, 74.6%-74.9%] vs 72.0% [95% CI, 71.8%-72.2%]), 52 081 patients with antihypertensive medication use and diagnosis at the time of surgery (53.3% [95% CI, 53.2%-53.4%] vs 49.4% [95% CI, 49.3%-49.5%]), and 35 055 patients with lipid-lowering medication use and diagnosis at the time of surgery (64.6% [95% CI, 64.5%-64.8%] vs 61.2% [95% CI, 61.1%-61.3%]). Among the subset of patients who discontinued medication, gastric bypass was also associated with a slightly lower incidence of medication restart up to 5 years after discontinuation. Specifically, the 5-year cumulative incidence of medication restart was lower after gastric bypass compared with sleeve gastrectomy among 19 599 patients who discontinued their diabetes medication after surgery (30.4% [95% CI, 30.2%-30.5%] vs 35.6% [95% CI, 35.4%-35.9%]), 21 611 patients who discontinued their antihypertensive medication after surgery (67.2% [95% CI, 66.9%-67.4%] vs 70.6% [95% CI, 70.3%-70.9%]), and 18 546 patients who discontinued their lipid-lowering medication after surgery (46.2% [95% CI, 46.2%-46.3%] vs 52.5% [95% CI, 52.2%-52.7%]).

CONCLUSIONS AND RELEVANCE

Findings of this study suggest that, compared with sleeve gastrectomy, gastric bypass was associated with a slightly higher incidence of medication discontinuation and a slightly lower incidence of medication restart among patients who discontinued medication. Long-term trials are needed to explain the mechanisms and factors associated with differences in medication discontinuation and comorbidity resolution after bariatric surgery.

Antiseizure Medication use in Gastric Bypass Patients and Other Post-Surgical Malabsorptive States

Healthcare professionals are encountering an increasing number of patients who have undergone bariatric surgeries. Antiseizure medications (ASM) have a narrow therapeutic window, and patients with malabsorptive states receiving ASM present a complex situation as the pharmacokinetics of these drugs have only been studied in patients with a normal functioning gastrointestinal tract. Patients with malabsorptive states may have altered pharmacokinetics, and there is limited literature to guide drug selection and dosage adjustment in patients with malabsorptive states. This review highlights pharmacokinetic parameters of common ASM, and considerations when managing patients on them. The effect of pH, lipophilicity, absorption, and metabolism should be taken into account when selecting and managing ASMs in this patient population. Based on these parameters, levetiracetam, and topiramate have fewer issues referable to absorption related to bariatric surgery while oral formulations of phenytoin, carbamazepine, oxcarbamazepine and valproic acid have reduced absorption due to effects of bariatric surgery based on the pharmacokinetic properties of these medications. Extended formulations should be avoided and ASM serum concentrations should be checked before and after surgery. The care of patients with epilepsy who are scheduled to undergo bariatric surgery should be guided by a multidisciplinary team including a pharmacist and a neurologist who should be involved in the adjustment of the ASMs throughout the pre-surgical and post-surgical periods.

Association between weight loss and reduced use of antihypertensive, hypoglycemic, psychotropic, and lipid-lowering drugs in patients undergoing bariatric surgery

Objectives: To analyze whether the weight reduction observed in bariatric surgery (Roux-en-Y gastric bypass; BGYR) is accompanied by a reduction in the use of antihypertensive, hypoglycemic, antilipidemic, and psychotropic drugs after 6 and 12 months. Methods: Longitudinal, retrospective study of 100 adult patients undergoing RYGB from May 2015 to January 2019, by laparotomy or laparoscopy. Data on age, body mass index (BMI), and the number of drugs used were recorded 6 and 12 months after surgery. Results: The mean age was 39.7 ± 9.7 years, and the majority were female (n = 78). The mean preoperative BMI was 43.7 ± 5.1 kg/m2, and the mean reduction in BMI after 6 months was 12.1 kg/m2 and 14.9 kg/m2 after 12 months. The reduction in antihypertensive drugs was 65.2% after 6 months and 96% after 12 months. The reduction in 6 months of hypoglycemic agents was 84.3%, and in 12 months, 98.3%. The average reduction in antidyslipidemic drugs was 86.7% in 6 months, and there was no record of using this medication after 12 months. Psychotropics showed a temporary reduction in use after 6 months with a return to levels close to the baseline after 1 year.There was no correlation between the variation in BMI and the use of drugs. Conclusions: there was a significant reduction in the use of drugs after 6 and 12 m, except for psychotropic drugs. The reduction in the use of drugs was not correlated with a reduction in BMI.

Adaptations in gastrointestinal physiology after sleeve gastrectomy and Roux-en-Y gastric bypass

Linked to the growing obesity epidemic, demand for bariatric and metabolic surgery has increased, the most common procedures being sleeve gastrectomy and Roux-en-Y gastric bypass. Originally, bariatric procedures were described as purely restrictive, malabsorptive, or combined restrictive-malabsorptive procedures limiting food intake, nutrient absorption, or both. Nowadays, anatomical alterations are known to affect gastrointestinal physiology, which in turn affects the digestion and absorption of nutrients and drugs. Therefore, understanding gastrointestinal physiology is crucial to prevent postoperative nutritional deficiencies and to optimise postoperative drug therapy. Preclinical and clinical research indicates that sleeve gastrectomy accelerates liquid and solid gastric emptying and small intestinal transit, and increases bile acid serum levels, whereas its effects on gastrointestinal acidity, gastric and pancreatic secretions, surface area, and colonic transit remain largely unknown. Roux-en-Y gastric bypass diminishes gastric acid secretion, accelerates liquid gastric emptying, and increases bile acid serum levels, but its effects on intestinal pH, solid gastric emptying, intestinal transit time, gastric enzyme secretions, and surface area remain largely unknown. In this Review, we summarise current knowledge of the effects of these two procedures on gastrointestinal physiology and assess the knowledge gaps.

Pregnancy after bariatric surgery - a narrative literature review

The purpose of this review was to analyze the literature about pregnancy after bariatric surgery. We searched for available articles on the subject from the last decade (2010 to 2020). The positive impact of bariatric surgery on the level of comorbidities and pregnancy and neonatal outcomes cannot be overrated. Weight loss after bariatric surgery reduces the incidence of obesity-related conditions in pregnancy. A pregnancy in a woman after bariatric surgery should be considered a high-risk pregnancy and taken care of by a multidisciplinary team with appropriate micronutrient and vitamin supplementation provided. Optimum time to conception should be chosen following the international recommendations. Every woman after bariatric surgery should be aware of symptoms of surgical complications and immediately contact their surgeon in case of abdominal pain.

Cost effectiveness of bariatric surgery in patients with obesity related comorbidities: A retrospective study

Background and Aim:

Bariatric surgery has been reported to be an effective but expensive method for obesity management. This study aimed to determine the economic benefit for patients who underwent bariatric surgery.

Methodology:

We conducted a retrospective chart review of patients who underwent bariatric surgery and was on medications for obesity-related comorbidities at the Obesity Research Center in King Khalid University Hospital, Riyadh, Saudi Arabia. Data on the use and cost of medications before and after bariatric surgery were collected.

Results:

A total of 266 patients, 107 males (40.23%), and 159 Females (59.77%) with a mean age of 41.06 years were included in the study. There was a reduction in the mean number of medications used by patients before and 1-year post-op (before: 1.84, after: 0.52), with a significant reduction in the cost of medications (SAR5152.24 before, and SAR1695.36 after, 67% reduction, P < 0.001). Patients < 32 years old had the most reduction in medications cost (76.64% reduction). No significant difference in the cost reduction after surgery between genders (P = 0.971). There were significant reductions in numbers of out-patient clinic visits (2.26 ± 2.43 to 1.57 ± 1.42) and in-patient hospitalizations (0.31 ± 0.57 to 0.10 ± 0.36) after surgery (P < 0.001 and P < 0.001, respectively).

Conclusion:

Bariatric surgery can be considered as a cost-effective treatment for patients with obesity-related comorbidities. A significant reduction has been found in post-operative medications cost, out-patient clinic visits and in-patient hospitalizations after bariatric surgery.

Pharmacokinetics of oral levonorgestrel and ethinylestradiol in women after Roux-en-Y gastric bypass surgery

BACKGROUND

Most patients undergoing Roux-en-Y gastric bypass (RYGB) are women in reproductive age. It is not known if bariatric surgery affects the pharmacokinetics of oral contraceptives.

OBJECTIVES

The primary objective was to evaluate ethinylestradiol (EE) and levonorgestrel (LNG) absorption in women undergoing RYGB, compared with nonoperated controls matched by age and body mass index (BMI). A secondary objective was to assess whether the time since surgery and BMI in the postoperative period influenced the absorption parameters.

SETTING

University hospital, Brazil.

METHODS

This study was designed to compare the maximum plasma concentration (C_max), the time to the peak plasma level (T_max), the area under the curve (AUC_0-8 and AUC_0-∞) after a single dose of a combined oral contraceptive with 0.03 mg EE and 0.15 mg LNG among 20 women after RYGB and 20 controls. Blood samples were obtained for 8 hours.

RESULTS

The mean LNG AUC_0-8 and LNG AUC_0-∞ were higher in RYGB group (P = .048 and P = .004, respectively). We found a positive correlation for LNG AUC_0-8 (P = .045) and AUC_0-∞ (P = .004) and the time since surgery, and we found a negative correlation for LNG C_max (P = .018), AUC_0-8 (P = .003), and AUC_0-∞ (P = .001) and BMI.

CONCLUSION

No significant differences were found in oral EE pharmacokinetics. The operated group showed higher mean LNG AUC_0-8 and AUC_0-∞ but it was not considered clinically significant. The present study suggests that RYGB may not affect EE and LNG absorption.

Bariatric Surgery can Lower the Efficacy of DOACs

A 39-year-old woman who was taking the contraceptive pill was admitted with right leg deep venous thrombosis (DVT). She was started on apixaban tablets, but after 8 days developed proximal progression of the DVT and pulmonary embolism. Her medical history later showed a history of sleeve gastrectomy. The patient responded to a vitamin K antagonist after heparin. The failure of the antithrombotic drug shed light on the efficacy and changed pharmacodynamics of direct oral anticoagulants (DOACs) after bariatric surgery in the absence of commercially available blood monitoring tests.

The Impact of Bariatric Surgery on Menstrual Abnormalities-a Cross-Sectional Study

INTRODUCTION

Obesity is associated with hyperestrogenism along with other hormonal abnormalities affecting the menstrual cycle. The most effective and decisive method of obesity treatment is bariatric surgery. The aim of this study was to analyze the impact of bariatric surgery on menstrual cycle, the incidence of menstrual abnormalities, hyperandrogenism manifestation, and contraception use.

MATERIALS AND METHODS

It was a cross-sectional study of 515 pre-menopausal women who had undergone bariatric surgery between 1999 and 2017 in a bariatric center. Data was collected via anonymous questionnaire, and the questions covered a 1-year period before the surgery and the last year before questionnaire completion.

RESULTS

Before the surgery, 38.6% of the patients reported irregular menstruations in comparison with 25.0% after bariatric surgery (RR = 0.65; 95%CI 0.53-0.79). The mean number of menstruations per year did not differ before and after surgery (10.2 ± 3.9 vs 10.4 ± 3.3; p < .45). There were no statistically significant differences in terms of prolonged menstruations, acne, and hirsutism prevalence. A total of 14.4% of patients before surgery reported estrogen-based contraception use in comparison with 15.0% after the surgery (p < .95). There were no significant differences in the frequency of OC use (11.0% before surgery vs 13.6% 12 months after the surgery vs 11.5% at the moment of survey administration; p < 0.46).

CONCLUSION

Bariatric surgery improves the regularity of the menstrual cycle in obese women in reproductive age. The lack of any changes in the combined hormonal contraception (CHC) use, especially OC, before and after bariatric surgery may be a result of a possibly low level of contraception counseling.

Effect of Roux-en-Y gastric bypass on the bioavailability of metoprolol from immediate and controlled release tablets: a single oral dose study before and after surgery

Objective

Roux-en-Y gastric bypass (RYGB) surgery induces major changes in the gastrointestinal tract that may alter the pharmacokinetics of orally administered drugs. Results from pharmacokinetic studies are sparse. This study aimed to investigate the effect of RYGB on the bioavailability of metoprolol from immediate release (IR) and controlled release (CR) tablets in female patient volunteers before and after surgery.

Methods

An explorative, two-phase, single oral dose pharmacokinetic study of metoprolol in female patients undergoing RYGB was carried out. The dose was administered twice in each patient, 1 month before and 6 months after surgery. After intake of either 100 mg of metoprolol IR or CR tablet serum concentration-time profiles of metoprolol were determined. The endpoint was the ratio of AUC_after/AUC_before of metoprolol.

Results

Twelve patients were included in the study (metoprolol IR: 7; metoprolol CR: 5). After intake of a metoprolol IR tablet major intraindividual and interindividual differences for area under the serum concentration versus time curve (AUC) of metoprolol before and after surgery were observed (range ratio AUC_{0-10 hours after}/AUC_{0-10 hours before}: 0.74-1.98). For metoprolol CR tablets a significant reduction in bioavailability of metoprolol was observed after surgery (range ratio AUC_{0-24 hours after}/AUC_{0-24 hours before}: 0.43-0.77).

Conclusion

RYGB may influence the bioavailability of metoprolol from an IR tablet. The magnitude of changes in bioavailability after RYGB requires close monitoring of patients using metoprolol IR tablets and dose adjustment if deemed necessary. RYGB clearly reduces the bioavailability of metoprolol from a CR tablet. After RYGB clinicians may consider to increase the dose according to clinical response.

Bariatric surgery is a cost-saving treatment for obesity-A comprehensive meta-analysis and updated systematic review of health economic evaluations of bariatric surgery

Demand for bariatric surgery to treat severe and resistant obesity far outstrips supply. We aimed to comprehensively synthesise health economic evidence regarding bariatric surgery from 1995 to 2018 (PROSPERO registration number: CRD42018094189). Meta-analyses were conducted to calculate the annual cost changes "before" and "after" surgery, and cumulative cost differences between surgical and nonsurgical groups. An updated narrative review also summarized the full and partial health economic evaluations of surgery from September 2015. N = 101 studies were eligible for the qualitative analyses since 1995, with n = 24 studies after September 2015. Quality of reporting has increased, and the inclusion of complications/reoperations was predominantly contained in the full economic evaluations after September 2015. Technical improvements in surgery were also reflected across the studies. Sixty-one studies were eligible for the quantitative meta-analyses. Compared with no/conventional treatment, surgery was cost saving over a lifetime scenario. Additionally, consideration of indirect costs through sensitivity analyses increased cost savings. Medication cost savings were dominant in the before versus after meta-analysis. Overall, bariatric surgery is cost saving over the life course even without considering indirect costs. Health economists are hearing the call to present higher quality studies and include the costs of complications/reoperations; however, indirect costs and body contouring surgery are still not appropriately considered.

Modern pharmacological treatment of obese patients

There are many angles to consider in drug treatment of obese patients. On the one hand, some specific weight loss drugs are available, on the other, several drugs are associated with unintentional weight changes. When treating an obese patient for any given disease, several physiological changes may influence the pharmacokinetic properties of the drugs required. Thus, increased body weight may influence the efficacy and safety of some drug treatments. Even more complicated is the situation after weight reduction surgery. Due to the various changes to the gastrointestinal tract induced by the different surgical techniques used, and the dynamic changes in body composition thereafter, drug dosing has to be constantly reconsidered. Whereas all of these issues are of clinical importance, none of them have been investigated in the necessary depth and broadness to ensure safe and efficacious drug treatment of the massively obese patient. Individual considerations have to be based on comorbidities, concomitant medication, and on specific drug properties, for example, lipophilicity, volume of distribution, and metabolism. In this article we summarize the data available on different aspects of drug treatment in the obese patient with the hope of improving patient care.

Chronic abdominal pain and persistent opioid use after bariatric surgery

Background and aims

Bariatric surgery remains a mainstay for treatment of morbid obesity. However, long-term adverse outcomes include chronic abdominal pain and persistent opioid use. The aim of this review was to assess the existing data on prevalence, possible mechanisms, risk factors, and outcomes regarding chronic abdominal pain and persistent opioid use after bariatric surgery.

Methods

PubMed was screened for relevant literature focusing on chronic abdominal pain, persistent opioid use and pharmacokinetic alterations of opioids after bariatric surgery. Relevant papers were cross-referenced to identify publications possibly not located during the ordinary screening.

Results

Evidence regarding general chronic pain status after bariatric surgery is sparse. However, our literature review revealed that abdominal pain was the most prevalent complication to bariatric surgery, presented in 3–61% of subjects with health care contacts or readmissions 1–5 years after surgery. This could be explained by behavioral, anatomical, and/or functional disorders. Persistent opioid use and doses increased after bariatric surgery, and 4–14% initiated a persistent opioid use 1–7 years after the surgery. Persistent opioid use was associated with severe pain symptoms and was most prevalent among subjects with a lower socioeconomic status. Alteration of absorption and distribution after bariatric surgery may impact opioid effects and increase the risk of adverse events and development of addiction. Changes in absorption have been briefly investigated, but the identified alterations could not be separated from alterations caused solely by excessive weight loss, and medication formulation could influence the findings. Subjects with persistent opioid use after bariatric surgery achieved lower weight loss and less metabolic benefits from the surgery. Thus, remission from comorbidities and cost effectiveness following bariatric surgery may be limited in these subjects.

Conclusions

Pain, especially chronic abdominal, and persistent opioid use were found to be prevalent after bariatric surgery. Physiological, anatomical, and pharmacokinetic changes are likely to play a role. However, the risk factors for occurrence of chronic abdominal pain and persistent opioid use have only been scarcely examined as have the possible impact of pain and persistent opioid use on clinical outcomes, and health-care costs. This makes it difficult to design targeted preventive interventions, which can identify subjects at risk and prevent persistent opioid use after bariatric surgery. Future studies could imply pharmacokinetic-, pharmacodynamics-, and physiological-based modelling of pain treatment. More attention to social, physiologic, and psychological factors may be warranted in order to identify specific risk profiles of subjects considered for bariatric surgery in order to tailor and optimize current treatment recommendations for this population.

Effects of Bariatric Surgery Observed in Postmortem Toxicology Casework

Bariatric surgery has been on the rise and patients often have multiple indications for pre- and post-operative pharmacotherapy. Procedures target the stomach and/or small intestine and affect weight loss through restriction, malabsorption, or a combination of the two. The absorption and/or metabolism of drugs via the gastrointestinal tract could be altered by different mechanisms. Several cases at the North Carolina Office of the Chief Medical Examiner's Toxicology Laboratory (NCOCME) have raised questions about the potential impact of these procedures on the disposition of drugs in the body and how that altered disposition may affect cause and manner of death. Overmedication and postmortem redistribution are not enough to explain the phenomena seen in some NCOCME bariatric surgery-related casework. Case examples include a 46-year-old female with a history of Roux-en-Y gastric bypass (RYGB) who suffered a witnessed collapse. Toxicological findings included elevated concentrations of oxymorphone at 0.49 mg/L in vena cava blood. A 67-year-old female, who died from vomiting and bacterial gastritis one day after placement of two intragastric weight-loss balloons, had elevated concentrations of duloxetine at 1.4 mg/L in the iliac vein blood and 9.3 mg/kg in the liver. Her medication was strictly controlled by her sister and gastric contents were without intact tablets or residue at autopsy.

The influence of bariatric surgery on oral drug bioavailability in patients with obesity: A systematic review

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.

Longitudinal Impacts of Gastric Bypass Surgery on Pharmacodynamics and Pharmacokinetics of Statins

PURPOSE

Undergoing Roux-en-Y gastric bypass (RYGB) is expected to affect orally administered drug absorption. Statins are commonly prescribed to patients with obesity for the prevention of atherosclerotic cardiovascular diseases by lowering cholesterol. This is the first longitudinal prospective study on impacts of RYGB on weight loss, pharmacodynamics, and pharmacokinetics of atorvastatin, rosuvastatin, and simvastatin, and their active metabolites, up to 1-year post-surgery.

METHODS

Forty-six patients were recruited, five patients on atorvastatin, twelve on rosuvastatin, nine on simvastatin, and twenty on no statin. The concentrations of atorvastatin, rosuvastatin, and simvastatin with their active metabolites were monitored.

RESULTS

Mean plasma concentrations of atorvastatin and metabolites and rosuvastatin normalized by the unit dose [(nM)/(mg/kg)] decreased by 3- to 6-month post-surgery. Conversely, simvastatin and its metabolite concentrations increased up to 6-month post-surgery, then declined to preoperative levels by 1-year post-surgery. The metabolisms of atorvastatin to hydroxyl-metabolites and simvastatin to simvastatin acid were decreased after RYGB. The weight loss and PD outcomes were comparable between statin and non-statin groups suggesting the key impacts were from RYGB. The discontinuation or reduction of dose of atorvastatin or rosuvastatin post-RYGB exhibited rebounds of LDL levels in some subjects, but the rebound was not apparent with patients on simvastatin pre-surgery.

CONCLUSION

Discontinuations of statin dosing post-RYGB require LDL monitoring and reducing the dose to half seems to have better results. Patients on statin treatment post-RYGB should be followed-up closely based on our pharmacokinetic findings, to ensure therapeutic effects of the treatment with minimal adverse effects.

Oral levothyroxine therapy postbariatric surgery: Biopharmaceutical aspects and clinical effects

BACKGROUND

Bariatric surgery can lead to changes in the oral absorption of many drugs. Levothyroxine is a narrow therapeutic drug for hypothyroidism, a common condition among patients with obesity.

OBJECTIVE

The purpose of this work was to provide a mechanistic overview of levothyroxine absorption, and to thoroughly analyze the expected effects of bariatric surgery on oral levothyroxine therapy.

METHODS

We performed a systematic review of the relevant literature reporting the effects of bariatric surgery on oral levothyroxine absorption and postoperative thyroid function. A PubMed search for relevant keywords resulted in a total of 14 articles reporting levothyroxine status before versus after bariatric surgery.

RESULTS

Different mechanisms may support opposing trends as to levothyroxine dose adjustment postsurgery. On the one hand, based on impaired drug solubility/dissolution attributable to higher gastric pH as well as reduced gastric volume, compromised levothyroxine absorption is expected. On the other hand, the great weight loss, and altered set-point of thyroid hormone homeostasis with decreased thyroid-stimulating hormone after the surgery, may result in a decreased dose requirement.

CONCLUSIONS

For patients after bariatric surgery, close monitoring of both the clinical presentation and plasma thyroid-stimulating hormone and T4 levels is strongly advised. Better understanding and awareness of the science presented in this article may help to avoid preventable complications and provide optimal patient care.

Fertility, Pregnancy and Lactation After Bariatric Surgery - a Consensus Statement from the OEGGG

Bariatric surgery is recommended when other weight loss interventions, such as lifestyle modification or medications, have failed. A considerable number of women undergoing bariatric surgery are of childbearing age; hence, it is necessary to be aware of the effects of bariatric surgery on pregnancy for managing these patients. Although bariatric surgery is associated with positive effects on cardiovascular and metabolic parameters, side effects such as anaemia, the risk of developing internal hernia, altered glucose metabolism and the risk of small for gestational age offspring have to be considered. Pregnant women with a history of gastric bypass should not undergo the oral glucose tolerance test (OGTT) due to the high risk of hypoglycaemia. There are no contraindications for vaginal delivery and breastfeeding. This paper has been published as a consensus statement by the Austrian Society of Gynaecology and Obstetrics (OEGGG).

Systematic review of drug bioavailability following gastrointestinal surgery

PURPOSE

Inter- and intraindividual pharmacokinetics variability in humans affects the way in which drugs act on the body. Gastrointestinal surgery has an impact on this variability and significantly alters the kinetics of drugs in post-surgical patients. The way in which pharmacokinetic profiles are modified depends on the type of operative procedure performed. The extent to which the absorption of different groups of drugs is affected varies according to the site and length of intestinal resections.

METHODS

A literature search was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. Three databases were searched: MEDLINE, Embase, and the Cochrane Library. For each drug, potential changes in absorption were described, including recommendations extracted from the results of the studies and collected according to authors' criteria as practical conclusions, and grades of recommendation were determined by levels of evidence using the Oxford Centre for Evidence-Based Medicine scale.

RESULTS

Sixty-eight articles were collected during the selection process after the bibliographic search. The main outcomes for 60 drugs from the various studies were classified according to each type of surgery.

CONCLUSIONS

Modifications in the digestive tract secondary to gastrointestinal surgery may compromise the bioavailability of drugs. Decreased absorption surface, gastric emptying speed, and gastric pH alteration are factors to be taken into account in the management of pharmacological treatment after surgery. Evidence supported by data in clinical practice is scarce, but after studying the pharmacokinetic profile of some molecules, it is possible to offer recommendations for its adaptation to the patient's clinical situation.

A gastrointestinal simulation system for dissolution of oral solid dosage forms before and after Roux-en-Y gastric bypass

Background

The Roux-en-Y gastric bypass (RYGB) is a bariatric procedure, greatly reducing the stomach size and bypassing the duodenum and proximal jejunum. Hence, RYGB may reduce the absorption and bioavailability of oral medication. For clinical decisions on the use of medication, knowledge of altered modifications in drug disposition is a prerequisite. An in vitro dissolution method for solid oral medications, simulating conditions before and after RYGB, might be a valuable tool to predict the pharmaceutical availability of medicines frequently used by patients after RYGB.

Objectives

To develop a gastrointestinal simulation system (GISS), mimicking conditions before and after RYGB for investigating dissolution characteristics of solid oral medications, and to assess the pharmaceutical availability of metoprolol from immediate-release (IR) and controlled-release (CR) tablets under these conditions.

Methods

With an adjusted, pharmacopoeial paddle dissolution apparatus, the GISS enables variation in parameters which are relevant to drug release in vivo: pH, volume, residence time, osmolality and agitation. Metoprolol tartrate 100 mg IR tablets and metoprolol CR tablets were tested. Release profiles were determined by measuring the concentrations of metoprolol spectrophotometrically.

Results

From IR tablets, under all conditions applied, >85% of metoprolol was released within 25 min. From all tested CR tablets >90% of metoprolol was released after 22 hours.

Conclusions

This GISS is a suitable dissolution system to assess pharmaceutical availability before and after RYGB. In patients who have undergone RYGB, no problems in pharmaceutical availability of metoprolol IR and CR tablets are to be expected. Any changes in response to metoprolol in patients after RYGB should therefore be ascribed to changes in bioavailability.

The Effect of Roux-en-Y Gastric Bypass Surgery in Morbidly Obese Patients on Pharmacokinetics of (Acetyl)Salicylic Acid and Omeprazole: the ERY-PAO Study

BACKGROUND

Data on the absorption of orally administered drugs following Roux-en-Y gastric bypass (RYGB) surgery in obese patients are limited and inconclusive. As it is difficult to predict changes in absorption, studies on frequently used drugs in this population are necessary. Acetylsalicylic acid (ASA) and omeprazole are two commonly prescribed drugs in obese patients.

METHODS

In this repeated measures study, omeprazole and salicylic acid (SA) serum concentrations were measured before and after RYGB in 34 morbidly obese subjects. Time to maximum concentration (Tmax), lag time (Tlag), maximum concentration (Cmax), and area under the serum concentration versus time curve (AUC) were calculated for both drugs to determine possible differences in drug absorption after the procedure.

RESULTS

For SA, Tmax significantly decreased after RYGB, while both Cmax and AUC0-24 significantly increased. For omeprazole, both Tmax and Tlag significantly decreased after RYGB, while Cmax significantly increased. Mean AUC0-12 significantly decreased post-surgery. The difference in AUC0-12 before and after surgery varied between subjects.

CONCLUSIONS

Our study shows a faster absorption of both ASA and omeprazole after RYGB. The exposure to ASA is higher post-surgery, but the standard dose of 80 mg does not need to be modified, considering its range in effective dose. The exposure to omeprazole is, on average, decreased after surgery. Clinicians should be aware to increase the dose of omeprazole if symptoms suggest inadequate response.

Impact of Sleeve Gastrectomy on Psychiatric Medication Use and Symptoms

BACKGROUND

Sleeve gastrectomy (SG) has become the primary bariatric surgery procedure in the U.S. Over 50% of people presenting for surgery have psychiatric diagnoses. The study purpose was to evaluate change in anxiety and depression symptoms and medication use after SG.

METHODS

Subjects completing SG with a diagnosis of anxiety and/or depression treated with medication were retrospectively identified from the electronic medical record (EMR) of Synergy Bariatrics, a department of the Erie County Medical Center. Phone outreach was made to complete seven-point global impression of change scale classifying symptom improvement or worsening in the 3- to 6-month postoperative period. Improvement or worsening was defined as either all reported symptoms improving or worsening or ≥1 improving or worsening while remaining unchanged. If ≥1 symptom improved and worsened, it was classified as mixed. No change required the same profile before and after surgery. Medication, dose, and changes were identified by EMR, verified during interview and classified as no change, discontinued, decreased, or increased.

RESULTS

59 subjects completed the interview. 21 subjects were diagnosed with anxiety. 13 (62%) had no change in therapy and 5 (24%) decreased. Symptoms improved in 12 (57%), worsened in 3 (14%), and mixed in 5 (24%). When symptoms improved, the same dose was present in 7/12 (58%) and dose decreased in 3 (25%). 51 subjects were diagnosed with depression. 32 (63%) had no change in therapy, 11 (21%) discontinued, and 4 (8%) decreased. Symptoms improved in 34 (67%), mixed in 10 (20%), worsened in 4 (8%), and unchanged in 3 (6%). When symptoms improved, the same regimen and dose was present in 21/34 cases (62%) and discontinued in 9 (26%).

CONCLUSION

Anxiety symptoms improved in >50% of subjects at predominantly the same or reduced dosage. Depression symptoms improved in 67% and commonly without therapy change. These data suggest evidence that patients undergoing SG while on medication for anxiety or depression may have early symptom improvement on the same or lessened dosage.

The Impact of Bariatric Surgery on Thyroid Function and Medication Use in Patients with Hypothyroidism

BACKGROUND

Bariatric surgery (BS) is effective in treating obesity and its associated comorbidities. However, there is a paucity of data on the effect of BS on thyroid function in hypothyroid patients, specifically in those treated with thyroid hormone replacement therapy (THR). The aim of this study was to assess the effect of BS on thyroid function and on THR dosage in patients with hypothyroidism.

METHODS

A retrospective analysis of prospectively collected data of all hypothyroid patients who underwent BS between 2010 and 2014 was performed. Data collected included demographic and anthropometric measurements, as well as changes in thyroid hormone levels and THR dosage up to a year from surgery.

RESULTS

During the study period, 93 hypothyroid patients (85 females, 91%), 83 of which treated with replacement thyroid hormone, underwent BS. Laparoscopic sleeve gastrectomy was performed in 77 (82.8%) and Roux-en-Y gastric bypass in 16 patients. Average age and body mass index (BMI) were 46.6 ± 11.2 years and 43.7 ± 6.4 kg/m², respectively. Mean BMI and thyroid-stimulating hormone (TSH) significantly deceased after 6 and 12 months following surgery whereas mean free T4 levels remained stable. TSH decrease was directly correlated to baseline TSH but not to BMI reduction. One year after surgery, 11 patients (13.2%) did not require THR, while the rest required a significantly lower average dose (P < 0.02).

CONCLUSIONS

There is a favorable effect of BS on the hypothyroid bariatric population. This includes improvement of thyroid function and reduction of thyroid medication dosages. Further studies are required to evaluate an influence of THR absorption and compare different types of bariatric surgeries.

Oral Anticoagulant Use After Bariatric Surgery: A Literature Review and Clinical Guidance

Bariatric surgery may alter the absorption, distribution, metabolism, or elimination (disposition) of orally administered drugs via changes to the gastrointestinal tract anatomy, body weight, and adipose tissue composition. As some patients who have undergone bariatric surgery will need therapeutic anticoagulation for various indications, appropriate knowledge is needed regarding anticoagulant drug disposition and resulting efficacy and safety in this population. We review general considerations about oral drug disposition in patients after bariatric surgery, as well as existing literature on oral anticoagulation after bariatric surgery. Overall, available evidence on therapeutic anticoagulation is very limited, and individual drug studies are necessary to learn how to safely and effectively use the direct oral anticoagulants. Given the sparsity of currently available data, it appears most prudent to use warfarin with international normalized ratio monitoring, and not direct oral anticoagulants, when full-dose anticoagulation is needed after bariatric surgery.

Practical Recommendations of the Obesity Management Task Force of the European Association for the Study of Obesity for the Post-Bariatric Surgery Medical Management

Bariatric surgery is today the most effective long-term therapy for the management of patients with severe obesity, and its use is recommended by the relevant guidelines of the management of obesity in adults. Bariatric surgery is in general safe and effective, but it can cause new clinical problems and is associated with specific diagnostic, preventive and therapeutic needs. For clinicians, the acquisition of special knowledge and skills is required in order to deliver appropriate and effective care to the post-bariatric patient. In the present recommendations, the basic notions needed to provide first-level adequate medical care to post-bariatric patients are summarised. Basic information about nutrition, management of co-morbidities, pregnancy, psychological issues as well as weight regain prevention and management is derived from current evidences and existing guidelines. A short list of clinical practical recommendations is included for each item. It remains clear that referral to a bariatric multidisciplinary centre, preferably the one performing the original procedure, should be considered in case of more complex clinical situations.

Effects of statin therapy on weight loss and diabetes in bariatric patients

BACKGROUND

Bariatric surgeries are considered effective treatments for weight loss and improved diabetes control. Statins increase diabetes onset in prospective clinical trials and many bariatric patients with metabolic disease are concurrently on statins.

OBJECTIVES

We retrospectively examined the relationship of statin therapy to weight loss, diabetes mellitus onset and remission, and metabolic outcomes after bariatric surgery.

SETTING

Hospital.

METHODS

A total of 1575 patients (1231 women) underwent laparoscopic adjustable gastric banding (n = 1035), Roux-en-Y gastric bypass (n = 468), or sleeve gastrectomy (n = 72) and were categorized as to statin use (n = 671 statin users) and diabetes status (n = 557 patients with diabetes) preoperatively and at one year follow-up.

RESULTS

New onset cases of diabetes did not differ between patients on and not on preoperative statins (3 versus 4 new diabetes cases, respectively), but diabetes resolved after surgery in 159 (23.7%) patients on preoperative statins and in only 124 (13.7%) patients not on preoperative statins (χ² = 26.1; P<.01). Patients ceasing statin therapy experienced more diabetes remission (n = 85 or 35.7%) than patients consistently using statin therapy at both time points (n = 57 or 17.0%; χ² = 27.3; P< .01).

CONCLUSION

In contrast to expectations, our results suggest that diabetes resolves with bariatric surgery more often in patients maintained on statin therapy than in those never on statin therapy whereas cessation of statin therapy is associated with the greatest reductions in diabetes prevalence. These results indicate an impact of statin use on metabolic outcomes following bariatric surgery; a randomized control trial is needed to examine carefully this relationship.

Guidelines for the follow-up of patients undergoing bariatric surgery

Bariatric surgery can facilitate weight loss and improvement in medical comorbidities. It has a profound impact on nutrition, and patients need access to follow-up and aftercare. NICE CG189 Obesity emphasized the importance of a minimum of 2 years follow-up in the bariatric surgical service and recommended that following discharge from the surgical service, there should be annual monitoring as part of a shared care model of chronic disease management. NHS England Obesity Clinical Reference Group commissioned a multi-professional subgroup, which included patient representatives, to develop bariatric surgery follow-up guidelines. Terms of reference and scope were agreed upon. The group members took responsibility for different sections of the guidelines depending on their areas of expertise and experience. The quality of the evidence was rated and strength graded. Four different shared care models were proposed, taking into account the variation in access to bariatric surgical services and specialist teams across the country. The common features include annual review, ability for a GP to refer back to specialist centre, submission of follow-up data to the national data base to NBSR. Clinical commissioning groups need to ensure that a shared care model is implemented as patient safety and long-term follow-up are important.

Proximal Roux-en-Y gastric bypass alters drug absorption pattern but not systemic exposure of CYP3A4 and P-glycoprotein substrates

STUDY OBJECTIVES

To evaluate the effect of Roux-en-Y gastric bypass surgery (RYGB) on the pharmacokinetics of midazolam (a CYP3A4 substrate) and digoxin (a P-glycoprotein substrate).

DESIGN

Prospective, nonblinded, longitudinal, single-dose pharmacokinetic study in three phases: presurgery baseline and postoperative assessments at 3 and 12 months.

PATIENTS

Twelve obese patients meeting current standards for bariatric surgery.

MEASUREMENTS AND MAIN RESULTS

At each study visit, patients received a single dose of oral digoxin and midazolam at 8 a.m. Blood samples were collected at regular intervals for 24 hours after dosing. Continuous 12-lead electrocardiogram (EKG), heart rate, blood pressure, and respiratory rate were monitored, and pharmacokinetic parameters from the three visits were compared. The peak plasma concentration (Cmax ) of midazolam increased by 66% and 71% at 3- and 12-month post-RYGB (p=0.017 and p=0.001, respectively), whereas the median time to peak concentration (Tmax ) was reduced by 50%. The mean Cmax for 1'-hydroxymidazolam increased by 87% and 80% at 3 and 12 months (p=0.001 and p<0.001, respectively). However, neither the area under the concentration-time curve (AUC) for midazolam nor the metabolite-to-parent AUC ratio changed significantly over time. For digoxin, the median Tmax decreased from 40 minutes at baseline to 30 and 20 minutes at 3 and 12 months, respectively. The mean AUC for digoxin, heart rate, and EKG patterns were similar across the three study phases.

CONCLUSION

Contemporary proximal RYGB increases the rate of drug absorption without significantly changing the overall exposure to midazolam and digoxin. The Cmax of a CYP3A4 substrate with a high extraction ratio was substantially increased after RYGB.

Review article: The nutritional and pharmacological consequences of obesity surgery

BACKGROUND

Obesity surgery is acknowledged as a highly effective therapy for morbidly obese patients. Beneficial short-term effects on common comorbidities are practically undisputed, but a growing data pool from long-term follow-up reveals increasing evidence of potentially severe nutritional and pharmacological consequences.

AIMS

To assess the prevalence, causes and symptoms of complications after obesity surgery, to elucidate and compare therapy recommendations for macro- and micronutrient deficiencies, and to explore surgically-induced effects on drug absorption and bioavailability, discussing ramifications for long-term therapy and prophylaxis.

METHODS

PubMed, Embase and MEDLINE were searched using terms including, but not limited to, bariatric surgery, gastric bypass, obesity surgery and Roux-en-Y, coupled with secondary search terms, e.g. anaemia, micronutrients, vitamin deficiency, bacterial overgrowth, drug absorption, pharmacokinetics, undernutrition. All studies in English, French or German published January 1980 through March 2014 were included.

RESULTS

Macro- and micronutrient deficiencies are common after obesity surgery. The most critical, depending on surgical technique, are hypoalbuminemia (3-18%) and deficiencies of vitamins B1 (≤49%), B12 (19-35%) and D (25-73%), iron (17-45%) and zinc (12-91%). Many drugs commonly administered to obese patients (e.g. anti-depressants, anti-microbials, metformin) are subject to post-operative and/or PPI-associated changes affecting bioavailability and absorption.

CONCLUSIONS

Complications are associated with pre-operative and/or post-operative malnutrition or procedure-related changes in intake, absorption and drug bioavailability. The high prevalence of nutrient deficiencies after obesity surgery makes life-long nutritional monitoring and supplementation essential. Post-operative changes to drug absorption and bioavailability in bariatric patients cast doubt on the validity of standard drug dosage and administration recommendations.

The use of drugs in patients who have undergone bariatric surgery

According to the World Health Organization, obesity has become an epidemic in the 21st century affecting around 300 million people of all ages worldwide. Clinical treatment modalities for this disease are limited and ineffective when it comes to morbidly obese patients (body mass index – the weight in kilograms divided by height in meters squared – surpasses 40 kg/m²). Therefore, the alternative, surgical treatment, is the best option for these patients, namely gastric restrictive procedures or an intestinal bypass culminating in a malabsorptive syndrome. In the past 20 years, there has been a 70% increase in the number of bariatric procedures all over the world. The main pharmacokinetic consequence observed in the postoperative period of these individuals is a higher or lower absorption of orally administered drugs.

Obesity and hormonal contraceptive efficacy

Obesity is a major public health concern affecting an increasing proportion of reproductive-aged women. Avoiding unintended pregnancy is of major importance, given the increased risks associated with pregnancy, but obesity may affect the efficacy of hormonal contraceptives by altering how these drugs are absorbed, distributed, metabolized or eliminated. Limited data suggest that long-acting, reversible contraceptives maintain excellent efficacy in obese women. Some studies demonstrating altered pharmacokinetic parameters and increased failure rates with combined oral contraceptives, the contraceptive patch and emergency contraceptive pills suggest decreased efficacy of these methods. It is unclear whether bariatric surgery affects hormonal contraceptive efficacy. Obese women should be offered the full range of contraceptive options, with counseling that balances the risks and benefits of each method, including the risk of unintended pregnancy.