Zoledronic Acid for Prevention of Bone Loss After BAriatric Surgery (ZABAS) (ZABAS)

May 28, 2026 updated by: Stinus Gadegaard Hansen
In a randomised placebo-controlled trial assess effects of zoledronic acid for prevention of bone and muscle loss after bariatric surgery.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

In individuals with severe obesity, bariatric surgery effectively reduces body weight, improves obesity related diseases and lowers mortality. A loss of bone and muscle mass and an increase in bone fracture risk are however seen after surgery. In this study it is examined if treatment with zoledronic acid (a drug used to treat osteoporosis) can prevent the bone and muscle loss after bariatric surgery. A single infusion of zoledronic acid or placebo is given before surgery. The study is blinded and randomized for methodological reasons. Bone and muscle scans, tests of muscle strength and physical performance and blood samples (for analysis of markers related to bone and muscle metabolism) are performed at inclusion and 12 and 24 months after surgery. A total of 60 adult individuals will participate. Results will be important for the evidence-based care of patients undergoing bariatric surgery and zoledronic acid.

Study design This is a single center randomized double-blind placebo-controlled study of zoledronic acid for prevention of bone and muscle loss after bariatric surgery. Routine bariatric surgery (RYGB or gastric sleeve) will be performed. The end of study is 24 months after surgery.

Study Population Patients referred for bariatric surgery at The Hospital South West Jutland, Esbjerg will be invited to participate.

Randomization After inclusion and baseline assessment, patients will be randomly assigned to either zoledronic acid or placebo with a 1:1 allocation. A randomization code stratifying an equal number of participants having RYGB or SG into each study arm will be applied.

Study Type

Interventional

Enrollment (Actual)

59

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Denmark
      • Esbjerg, Denmark, 6700
        • Hospital South West Jutland

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

35 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • 35 years old or older
  • Eligible for bariatric surgery (BMI>35 kg/m2 with obesity-related comorbidity)

Exclusion Criteria:

  • Pregnancy or breastfeeding.
  • Chronic kidney disease with estimated GFR<45 ml/min.
  • Hypocalcemia .
  • Hypersensitivity to bisphosphonates, mannitol, sodium citrate or water.
  • Metabolic bone disease (osteoporosis is allowed).
  • Prior treatment with anti-osteoporotic agents.
  • Treatment with oral glucocorticoids
  • Other diseases with known effects on bone metabolism

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Placebo Comparator: Placebo
Drug: Placebo
as above
Experimental: Zoledronic Acid
Active treatment
Drug: Zoledronic Acid
  • A single treatment 21 days before bariatric surgery with Zoledronic acid 5 mg or placebo (an interval of 5 to 180 days is accepted)
  • Pharmaceutical form: Solution for infusion (100 ml normal saline containing 5 mg zoledronic acid or placebo)
  • Administration: slow intravenous infusion with a duration of at least 15 minutes

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Quantitative Computed Tomography (QCT)
Time Frame: Change from baseline to 12 and 24 months after bariatric surgery
Volumetric bone mineral density at the lumbar spine (L1 -L2) (Mindways QCT Pro software, Texas, USA).
Change from baseline to 12 and 24 months after bariatric surgery

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
QCT
Time Frame: Change from baseline to 12 and 24 months after bariatric surgery
Volumetric BMD at the proximal femur (Mindways QCT Pro software, Texas, USA).
Change from baseline to 12 and 24 months after bariatric surgery
Biochemical calcium-metabolic markers
Time Frame: Change from baseline to 12 and 24 months after bariatric surgery
Calcium, parathyroid hormone, vitamin D and markers of bone remodeling (CTX, P1NP).
Change from baseline to 12 and 24 months after bariatric surgery
DEXA
Time Frame: Change from baseline to 12 and 24 months after bariatric surgery
Bone mineral density at the lumbar spine and total hip (Hologic Discovery, Waltham, MA, US).
Change from baseline to 12 and 24 months after bariatric surgery
HR-pQCT
Time Frame: Change from baseline to 12 and 24 months after bariatric surgery
Radius and tibia bone microarchitecture (Scanco Medical AG, Brutisellen, Switzerland).
Change from baseline to 12 and 24 months after bariatric surgery
Cortical bone stiffness
Time Frame: Change from baseline to 12 and 24 months after bariatric surgery
Cortical bone material strength index (BMSi) assessed using microindentation at the anterior surface of the mid-tibia diaphysis (OsteoProbe, Active Life Scientific, California, US).
Change from baseline to 12 and 24 months after bariatric surgery
Muscle Strength
Time Frame: Change from baseline to 12 and 24 months after bariatric surgery
Upper and lower limb muscle strength assessed using dynamometers (foot, knee, shoulder, hand)
Change from baseline to 12 and 24 months after bariatric surgery
Physical function
Time Frame: Change from baseline to 12 and 24 months after bariatric surgery
Short physical performance battery (SPPB), Stair Climb, 2 minute walking test
Change from baseline to 12 and 24 months after bariatric surgery

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Stinus Gadegaard Hansen

Collaborators

Odense University Hospital
University of Southern Denmark
Research Unit of Health Sciences, Hospital of South West Jutland
OPEN - Odense Patient data Explorative Network, The University of Southern Denmark, Odense, Denmark
Department of Radiology and Nuclear Medicine, Hospital of Southwest Jutland, 6700 Esbjerg, Denmark

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

February 20, 2021

Primary Completion (Actual)

November 1, 2023

Study Completion (Actual)

August 12, 2024

Study Registration Dates

First Submitted

January 27, 2021

First Submitted That Met QC Criteria

February 3, 2021

First Posted (Actual)

February 5, 2021

Study Record Updates

Last Update Posted (Actual)

June 1, 2026

Last Update Submitted That Met QC Criteria

May 28, 2026

Last Verified

June 1, 2022

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 20/41068

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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