Raising the Standard: The Role of the Clinical Pharmacist in the Care of the Bariatric Surgery Patient

| September 1, 2021

by Alyssa Pollock, PharmD; Anthony T. Petrick, MD, FACS, FASMBS; and Dominick Gadaleta, MD, FACS, FASMBS

Ms. Pollock is an Assistant Professor at Creighton University School of Pharmacy and Health Professions in Omaha, Nebraska. Dr. Petrick is Chief Quality Officer, Geisinger Clinic; Director of Bariatric and Foregut Surgery, Geisinger Health System in Danville, Pennsylvania. Dr. Gadaleta is Chair, Department of Surgery, South Shore University Hospital; Director, Metabolic and Bariatric Surgery, North Shore and South Shore University Hospitals, Northwell Health in Manhasset, New York; Associate Professor of Surgery, Zucker School of Medicine at Hofstra/Northwell in Hempstead, New York.

Funding: No funding was provided for this article.

Disclosures: The authors report no conflicts of interest relevant to the content of this article.

Bariatric Times. 2021;18(9):16–17

Over the past decade, the number of bariatric surgeries performed annually in the United States (US) grew significantly, increasing approximately 60 percent from 2011 to 2019.1 Bariatric surgery is expected to undergo continued growth in years to come, increasing the need for the multidisciplinary approach these patients require.2

Patients are considered for bariatric surgery based on body mass index (BMI) and coexisting conditions.3 Secondary to severe obesity and multiple chronic conditions, these patients can be on complex medication regimens that require adjustments throughout the bariatric surgery journey. Furthermore, patients undergoing bariatric surgery are subject to malabsorptive changes, not just for vitamins and minerals, but also medications. Oral medications are subject to variability in disintegration, dissolution, permeation, absorption, and metabolism via anatomical surgical changes and postoperative weight loss. Postoperative metabolic changes can complicate management of these patients’ medication regimens.4 As part of a multidisciplinary bariatric team, clinical pharmacists play a unique role in promoting patient safety and adherence by recognizing potential pharmacokinetic changes induced by surgery and how to adjust medication regimens to overcome those challenges.  

Implementation of clinical pharmacy services in bariatric surgery programs has been found to reduce medication errors, promote cost-avoidance, and lead to positive patient-reported outcomes.5,6 Though job descriptions might vary, limited literature published to date shows similarities in the services pharmacists provide in bariatric surgery programs.7 This article describes pharmacist roles on the bariatric surgery team based on more than a decade of experience at CHI Health Immanuel, a community hospital program in Omaha, Nebraska. The activities of the bariatric pharmacist are designed to promote quality improvement and patient safety. Because clinical pharmacy services for bariatric programs are not standardized, activities might differ at other institutions.

Preoperative Consultation

Need for pharmacist intervention often begins weeks to months before the patient is admitted for surgery. Having an updated and accurate medication list is a vital first step. Once this medication history is obtained, the pharmacist can evaluate and identify medication changes that will be needed prior to or after bariatric surgery. Interventions that could occur during this time include drug formulation changes (e.g., extended-release to immediate-release), disease state management, immunosuppressant management to minimize postoperative infection risk (e.g., steroid tapering and perioperative holding parameters), anticoagulation management to optimize clot versus bleed risk, and tapering off chronic obesity medications that could interfere with anesthesia (e.g., phentermine). 

Empiric formulation changes might be temporarily or permanently needed after surgery to ensure solid medications are small enough to pass through the altered gastrointestinal anatomy and optimal absorption occurs as postoperative pharmacokinetic changes develop. The pharmacist evaluates tablet and capsule sizes and release mechanisms to identify the need to convert large noncrushable extended-release tablets to the appropriate dose and frequency of immediate-release tablets or liquid forms and clarify if capsules can be opened and sprinkled on food or dissolved.4

The pharmacist plays a role in disease state management by suggesting medication changes and monitoring as clinically appropriate. Preoperative interventions could include adjusting insulin doses and diligently monitoring blood glucose, closely monitoring the international normalized ratio (INR) due to vitamin K-dependent warfarin metabolism, and educating patients on medications with nutrient or caloric-dependent absorption (e.g., certain antipsychotics, bile acid sequestrants, rivaroxaban). These interventions can be particularly important during the preoperative low-carbohydrate diet, especially for patients with diabetes. Proactive medication changes might also be required to avoid medications known to increase the risk of gastrointestinal bleeding. Addressing these changes preoperatively educates the patient and involves them in decision making at a more opportune time versus during postoperative recovery. It also allows the patient time to coordinate new prescriptions with original prescribers and fill these prior to surgery to increase the chance of postoperative compliance and safety with new regimens.   

Perioperative Pharmacy Involvement

A bariatric surgery pharmacy consult can be built into the inpatient postoperative order set. Once admitted to the medical-surgical unit, postoperative orders are released, and the consult is received by the pharmacist, which gives them the ability to perform medication reconciliation. This includes reviewing the patient’s home regimen and ordering necessary medications in a timely manner, as appropriate, based on drug formulation availability and hospital formulary. Necessary maintenance medications are ordered cautiously due to the pharmacokinetic alterations of oral formulations and physiologic changes in this immediate postoperative period.8 The pharmacist might also round with the bariatric surgery team, assisting with addressing patient concerns (e.g., pain control, nausea, vomiting) and educating surgery residents on postoperative medication adjustments. Discharge medication reconciliation can be performed by the pharmacist if the consult from the order set allows. Having a trained bariatric pharmacist who understands postoperative physiological changes and their impact on potential medication therapy assist in discharge reconciliation facilitates patient safety in transitions of care. The pharmacist ensures no duplicate medications are ordered, appropriate resumption of held medications, and discontinuation of unnecessary medications and evaluates postoperative appropriateness of medications and doses (e.g., holding diuretics and medications with diuretic potential to avoid dehydration and renal injury).

Patient education is a vital component of the perioperative phase. The pharmacist educates the patient on size restrictions of medications, instructions for administration modifications, revisions to therapy, and monitoring parameters. The bariatric pharmacist might also be intricately involved in creating or updating perioperative bariatric order sets containing medication orders and can help create clear nursing administration instructions that are appropriate for the bariatric surgery patient.

Postoperative Considerations  

If the bariatric pharmacist’s main practice site is in the hospital, postoperative involvement might be challenging. This would augment the importance of preoperative and discharge patient education. This education provides the patient with any medication instructions or suggestions regarding drug dosage or formulation adjustments that were recommended by the bariatric team that can be utilized at postoperative provider appointments.

In addition to postoperative anatomical changes, substantial weight loss can produce changes in body composition and liver function, which can alter drug metabolism and distribution and renal function. Significant weight loss can rapidly improve obesity-related comorbidities, such as hypertension, diabetes, and hyperlipidemia; therefore, tapering of medications that treat these diseases should be considered postoperatively as appropriate.  Patients are most prone to these changes in the first few months up to two years after surgery; however, patient diversity and postoperative variability can be significant.8 This emphasizes the importance of close, continued monitoring, especially for more dynamic disease states and medications that rely on weight-based dosing or are subject to the pharmacokinetic changes produced by bariatric surgery. 

At North Shore University Hospital, a clinical pharmacist has been part of the multidisciplinary team since 2014. The process differs in that the initial patient contact occurs as part of the presurgical testing process. The medications are reviewed with the patient, and recommendations are made and communicated with the bariatric surgical team, as well as the prescribing physician and primary care physician. Additionally, medication reconciliation is done prior to discharge to ensure patient understanding and provide continued support to the patient and surgical team. This same process was adopted at the newly established South Shore University Hospital bariatric program in 2019 with immediate benefits noted by patients and staff.


Currently, there are no published guidelines for medication management after bariatric surgery in the US. Often, this responsibility is left to multiple different providers that interact with the patient but have limited knowledge of the physiologic changes induced by bariatric surgery or the perioperative protocols. Literature lacks clear recommendations, compounding the challenge presented in managing bariatric surgery patients. Clinical pharmacists can utilize their extensive knowledge of drug formulations and pharmacokinetics to help promote patient safety and enhance the bariatric surgery experience for the patient.


Thank you to April Smith, PharmD, MA, BCPS, for assistance with this article.


  1. Estimate of bariatric surgery numbers, 2011-2019. American Society for Metabolic and Bariatric Surgery website. 2019. https://asmbs.org/resources/estimate-of-bariatric-surgery-numbers. Accessed 20 July 2021.
  2. Global bariatric surgery market expected to reach USD 3,518 million by 2024: Zion Market Research. Zion Market Research. 2019. https://www.globenewswire.com/en/news-release/2019/02/08/1713843/0/en/Global-Bariatric-Surgery-Market-Expected-to-Reach-USD-3-518-Million-By-2024-Zion-Market-Research.html. Accessed 20 Jul 2021. 
  3. Mechanic JI, Apovian C, Brethaue S, et al. Clinical practice guidelines for the perioperative nutrition, and nonsurgical support of patients undergoing bariatric procedures–2019 update. Surg Obes Relat Dis. 2020;16(2):175–247.
  4. Lorico S, Colton B. Medication management and pharmacokinetic changes after bariatric surgery. Can Fam Physician. 2020;66(6):409–416.
  5. Bariatric surgery clinical pharmacist integration: business case. USCF Health. https://cdn.ymaws.com/www.cshp.org/resource/cform/1330383/20180402_020440_10678.pdf. Accessed 21 July 2021.
  6. Graham Y, Callejas-Diaz L, Parkin L, et al. Exploring the patient-reported impact of the pharmacist on pre-bariatric surgical assessment. Obes Surg. 2019;29(3):891–902.
  7. Smith A, Huels A, Leung A. Clinical pharmacy bariatric surgery consult services. Poster presented at American Society for Metabolic and Bariatric Surgery Annual Meeting. 9 Oct 2015. 
  8. Porat D, Dahan A. Medication management after bariatric surgery: providing optimal patient care. J Clin Med. 2020;9(5):1511.  

Tags: ,

Category: Past Articles, Raising the Standard

Comments are closed.