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Effect of Gastric Bypass on the Absorption of Metformin (ABSORB-Met)

This study has been completed.
Information provided by:
University of Alberta Identifier:
First received: November 12, 2009
Last updated: March 2, 2011
Last verified: March 2011

Background: Gastric bypass is the most commonly performed type of bariatric (obesity) surgery, has dramatically increased in popularity and is now considered to be preferred treatments in severely obese patients that fail non-surgical therapy - particularly in patients with type 2 diabetes. Drug malabsorption is a potential concern post-gastric bypass because intestinal length is reduced.

Purpose: The purpose of this controlled, pharmacokinetic study is to determine whether the absorption of a single dose of metformin, the first line drug treatment in patients with type 2 diabetes, is significantly reduced after gastric bypass.

Methods: A single dose of standard release metformin 1000 mg will be administered to patients who have undergone gastric bypass and to patients who have not received surgery but are on the wait list (wait-listed controls). Blood sampling and urine sampling will occur in standardized fashion over the ensuing 24 hours to measure and compare the absorption of metformin between study arms. 34 patients total will be recruited.

Significance: Following completion of this study, we will better understand how gastric bypass affects metformin absorption. Ultimately, this information will help to ensure that this patient population is receiving optimal doses of this important drug treatment.

Obesity Gastric Bypass

Study Type: Observational
Study Design: Observational Model: Case Control
Time Perspective: Prospective
Official Title: Effect of Gastric Bypass on the Absorption of Metformin

Resource links provided by NLM:

Further study details as provided by University of Alberta:

Primary Outcome Measures:
  • Area-under-the-curve of metformin absorption (0-infinity) [ Time Frame: cross-sectional ]

Secondary Outcome Measures:
  • AUC (0-24h) [ Time Frame: cross-sectional ]
  • tmax [ Time Frame: cross-sectional ]
  • cmax [ Time Frame: cross-sectional ]
  • AUC glucose (0-8h) [ Time Frame: cross-sectional ]
  • bioavailability of metformin (urine metformin concentration from 0-infinity) [ Time Frame: cross-sectional ]

Estimated Enrollment: 34
Study Start Date: September 2009
Study Completion Date: December 2010
Post Gastric Bypass
Obese Controls
age, BMI, gender matched


Ages Eligible for Study:   18 Years to 60 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Probability Sample
Study Population

Post gastric bypass and obese controls

  1. Male and Female
  2. 18 - 60 years old
  3. ≥ 3 months post-RYGB surgery or wait listed for bariatric surgery
  4. Able to provide written informed consent.

Inclusion Criteria:

Patients living within and around Edmonton that have been referred to the Alberta Health Services Weight Wise Program

Exclusion Criteria:

  1. Undergone or undergoing revision of a previous bariatric procedure
  2. Any major post-operative gastrointestinal complications, such as an anastomotic leak, outlet obstruction or persistent vomiting
  3. Currently on metformin therapy
  4. Any contraindications to metformin therapy such as:

    1. allergy to the drug
    2. chronic metabolic acidosis
    3. history of lactic acidosis
    4. liver failure or baseline liver enzymes higher than 3-fold above the upper limit of normal
    5. congestive heart failure
    6. renal failure (glomerular filtration rate < 60 ml/min)
    7. alcoholism
    8. acute illness
    9. fatty liver disease
  5. Pregnant or nursing
  6. Not taking furosemide or nifedipine (both drugs may increase metformin absorption by 15-20%)the day of visit 2.
  7. Any other medical, social or geographic condition, which, in the opinion of the investigator would not allow safe completion of the study protocol
  Contacts and Locations
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Please refer to this study by its identifier: NCT01013051

Canada, Alberta
University of Alberta Hospital Clinical Investigation Unity
Edmonton, Alberta, Canada, T6G2B7
Sponsors and Collaborators
University of Alberta
Principal Investigator: Raj Padwal, MD University of Alberta
  More Information

Responsible Party: Raj Padwal, University of Alberta Identifier: NCT01013051     History of Changes
Other Study ID Numbers: RES0002122
Study First Received: November 12, 2009
Last Updated: March 2, 2011

Keywords provided by University of Alberta:
gastric bypass

Additional relevant MeSH terms:
Hypoglycemic Agents
Physiological Effects of Drugs processed this record on August 23, 2017