Medication Use in Bariatric Surgery: Evaluation of Perioperative Adjustments

Abstract

Purpose: A retrospective evaluation was performed to assess whether medications for patients undergoing bariatric procedures are effectively optimized to ensure safe medication transitioning.

Methods: This retrospective chart review was a single-center study enrolling 149 consecutive patients undergoing laparoscopic banding or Roux-en-Y gastric bypass procedures between June 2, 2008, and September 30, 2008. Patients were aged 18 to 80 years with no exclusions. Characteristics assessed were baseline demographics and medications prior to admission, during admission, and post-admission. Primary optimization characteristics for medications at discharge include those medications with preferred formulations such as chewable compounds and those unable to be crushed such as some extended-release products.

Results: Of bariatric procedures performed, 89 (60%) were laparoscopic banding and 59 (40%) were Roux-en-Y gastric bypass procedures. The average patient was 44.5 years of age with a BMI of 46.3 kg/m². Of the 869 (5.8/patient) medications at discharge, 157 (18%) of those medications were identified as ones that could have been optimized. This included 53 (34%) medications that had preferred formulations available such as liquid or crushable forms and 31 (20%) medications that were inappropriately crushed, suggesting that they required a therapeutic equivalent alternative such as immediate-release or non-enteric-coated formulations.

Conclusion: Patients undergoing bariatric procedures at our institution often have complicated medication regimens that could be optimized with pharmacy involvement to ensure safe and efficacious medication regimen transitioning.

Background and Purpose:

The bariatric surgeons at our institution had independently managed medication transitioning during the bariatric procedure perioperative period without clinical pharmacy involvement. Medication transitioning is the alteration of a patient’s medications in response to anatomical changes that occur during surgery. Medication safety concerns prompted the Bariatric Surgery Service to request assistance with medication transitioning from the Department of Pharmacy due to the increasing complexity of their patients’ medication treatment regimens, including psychiatric medications. We performed a literature search to establish criteria for a retrospective chart review that would identify current best practice suggestions for medication transitioning in order to compare these to our institution’s current practice. The literature lacked information regarding direct pharmacy involvement with this patient population perioperatively.

Significant changes in anatomy that occur following a bariatric procedure have the potential to affect the pharmacokinetic and pharmacodynamic profiles of multiple medications.^1-3 At our institution, the following surgeries are performed: Roux-en-Y gastric bypass, which is malabsorptive and restrictive, and laparoscopic gastric banding, which is restrictive but does not alter anatomy. Two common themes described in the literature were medication formulation adjustment due to pills that were too large to be consumed as a result of surgery and medication adjustment from extended-release to immediate-release due to malabsorption resulting from surgery.^1-3 Administration of drugs via a liquid, crushed, or chewable form can improve drug dissolution. Tablets may be swallowed whole if they are no larger than the diameter of a pencil eraser.

The purpose of this retrospective chart review is to evaluate whether our institution’s current medication transitioning practices are safe, efficacious, and clinically appropriate from a pharmacy perspective.

Methods:

A single-center, retrospective chart review was conducted of 149 consecutive patients for surgeries performed from June 2, 2008, to September 30, 2008. The patients ranged from 18 to 80 years of age and were undergoing laparoscopic banding or Roux-en-Y gastric bypass. No patients within this time period were excluded. The following patient demographic averages were identified: age, height, weight, body mass index (BMI), and length of stay. Gender, type of surgery, co-morbidities, and discharge status were documented for each patient. For each patient, the number of medications that fit each of the following criteria was recorded: taken prior to admission, continued or held on admission, newly started, formulated as sustained-release products, those that cannot be crushed, and those continued at discharge. The primary endpoints were medications requiring optimization, including sustained-release medications not changed to immediate-release formulation; medications held on admission and not restarted at discharge; medications not changed to intravenous formulations or crushable equivalents; calcium carbonate not changed to calcium citrate; and the number of days that psychiatric medications were held.

Results:

From June 2, 2008, to September 30, 2008, 149 consecutive surgical patients were reviewed. (Baseline demographics can be found in Table 1, below.) The patients’ average age was 44.5 years and average body mass index (BMI) was 46.3 kg/m². There were 132 females (89%). Of the surgeries, 89 (60%) were laparoscopic gastric banding surgeries and 59 (40%) were Roux-en-Y gastric bypass surgeries.

The patients received a total of 730 medications prior to their procedures (4.91/patient). Of these 730 medications, 201 (28%) were continued on admission. For the 201 continued medications, 37 (19%) were changed to a therapeutic equivalent, 40 (20%) were changed to an IV formulation, and 122 (61%) were unchanged from the home regimen.

Of the 730 pre-procedure medications, 377 (58%) had no follow-up at discharge; patients were not given specific instructions to follow post-operatively regarding these medications. Also, pre-procedure, there were 41 (6%) sustained-release medications. Of these 41 sustained-release medications, 21 (51%) were held on admission, 10 (24%) were changed to IV formulation, 6 (15%) were changed to a therapeutic equivalent, and 4 (10%) were unchanged. Five of the sustained-release medications were restarted at discharge.

Patients were prescribed 901 (6.1/patient) new oral medications during hospitalization and 869 (5.8/patient) medications at discharge. It was determined that 157 (18%) of discharge medications had the potential to be optimized by adjusting the medication to a safer and more efficacious alternative. Fifty-three (34%) of the 157 medications were identified as having preferred formulations such as chewable or oral solutions. The remaining potential optimizations were identified as 31 (20%) medications that cannot be crushed, 24 (15%) calcium carbonate supplements to be transitioned to calcium citrate, 4 (2.5%) psychiatric medications held for 1 day, 22 (14%) psychiatric medications held for 2 days, and 23 (14.5%) psychiatric medications held for at least 3 days. Discharge notes for these patients all included general instructions to continue to crush all medications at home unless otherwise specified for a specific agent.

Discussion:

The retrospective evaluation of medication use in bariatric surgery patients at our institution identified numerous opportunities for adjustments to safer or more therapeutic alternatives and dosage forms. Many formulations that should not have been crushed were continued post-operatively without change. Also, many of the discharge medication instructions were provided in generalized form.

Pharmaceutical care guidelines for the bariatric surgery patient are limited in the literature, although the literature does include some general and some drug-specific recommendations. Absorption properties of drugs are affected by both the drug formulation and the type of surgery. Procedures that involve gastric restriction such as gastric banding are less likely to alter drug absorption than are procedures such as Roux-en-Y that involve intestinal diversion.¹ Thus, malabsorption is of greatest concern with drugs that have a narrow therapeutic window and with drugs that require therapeutic drug monitoring. Decreased drug dissolution resulting in diminished absorption can be mitigated by administration of drugs in a liquid, crushed, or chewable form. No tablets whose diameter is larger than a pencil eraser should be swallowed whole.³ Extended-release formulations should be changed to immediate-release forms to avoid potential decreased bioavailability and prolonged dissolution of the former.³

After a Roux-en-Y bariatric procedure, less gastric acid is produced, resulting in a higher gastric pH. Substances that depend on acidic environments for solubility and absorption purposes, such as rifampin, digoxin, ketoconazole, and iron supplements, will be less readily absorbed under these circumstances.² One way to improve absorption of iron supplements would be to add ascorbic acid.² For example, calcium carbonate requires an acidic environment and should be changed to calcium citrate 1200-1500 mg per day to improve absorption.²

Conclusions:

The results from the retrospective chart review indicated that there is an unmet need and opportunity for a pharmacy-driven consultation program to ensure continuity of care in the bariatric patient population. Thus, the Bariatric Surgery Service and the Department of Pharmacy determined that the initiation of a Bariatric Pharmacy Consult Service could improve medication management in bariatric surgery patients with complicated regimens as determined by their surgeon.

References:

1. Fussy, SA. The skinny on gastric bypass: what pharmacists need to know. US Pharmacist. 2005;2:HS-3-HS-12.

2. Miller AD, Smith KM. Medication and nutrient administration considerations after bariatric surgery. Am J Health-Syst Pharm. 2006;63:1852-1857.

3. Sardo P, Walker J. Bariatric Surgery: Impact on Medication Management. Hospital Pharmacy. 2008;43:113-120.

Authors:

Jennifer G. Catella, PharmD, BCPS

Senior Staff Pharmacist

Brigham and Women’s Hospital

L2 Pharmacy Department

75 Francis St, Boston, MA 02215

Jon B. Silverman, BS, PharmD

Investigational Drug Services Supervisor

Brigham and Women’s Hospital

L2 Pharmacy Department

75 Francis St, Boston, MA 02215

Karen Fiumara, PharmD

Patient Safety Manager

Brigham and Women’s Hospital

1 Brigham Circle, Boston, MA 02215

William W. Churchill MS, RPh

Executive Director of Pharmacy

Brigham and Women’s Hospital

L2 Pharmacy Department

75 Francis St, Boston, MA 02215

The authors of this submission have no disclosures concerning possible financial or personal relationships with commercial entities that may have a direct or indirect interest in the subject matter.

Table 1.

Patient Characteristics

Results

N=149

Female — no. (%)

132 (89)

Average weight

134 kg

Average height

65 inches

Average age

44.5 years

Average BMI

46.3 kg/m²

Average length of stay

2.84 days

Type of surgery — no. (%)

Lap band

89 (60)

Roux-en-Y

59 (40)

Co-morbidities - no. (%)

No. of pts with >1 co-morbidity

142 (95)

HTN

67 (45)

OSA

71 (48)

DM

32 (21)

GERD

76 (51)

Asthma/COPD

41 (28)

Psych disorder

51 (34)

Other co-morbidities

1/patient

Follow-up Information

Patients discharged to home

100 (100)

Table 2. Perioperative Medication Adjustments

Medications pre-operative

730 (4.91/patient)

Continue on admission — no. (%)

201 (28)

Changed to therapeutic equivalent

37 (19)

Changed to IV formulation

40 (20)

Unchanged from home regimen

122 (61)

Sustained Release Medications — no. (%)

41 (6)

Held on admission

21 (51)

Changed to IV formulation

10 (24)

Changed to therapeutic equivalent

6 (15)

Unchanged

4 (10)

Sustained Release Meds restarted at discharge — no. (%)

5 (12)

Restarted at discharge without instructions — no. (%)

377 (58)

New medications during hospitalization

901 (6.1/patient)

Medications at discharge

869 (5.8/patient)

Potential for optimization — no. (%)

157 (18)

Preferred formulation (ie. Chewable, oral solution)

53 (34)

Medications that cannot be crushed

31 (20)

Calcium carbonate to calcium citrate

24 (15)

Psych medication held 1 day

4 (2.5)

Psych medication held 2 day

22 (14)

Psych medication held >3 days

23 (14.5)