Skip to page content Mission Information


Bisphosphonates As A Countermeasure To Space Flight Induced Bone Loss (SMO 021)
Research Area:
Skeletal physiology
Species Studied
Scientific Name: Homo sapiens Species: Human

The purpose of this combined research study is to determine whether bisphosphonates, in conjunction with the routine in-flight exercise program, will protect International Space Station (ISS) crewmembers from the regional decreases in bone mineral density documented on previous ISS flights. Two dosing regimens will be tested: (1) an oral dose of 70 mg of alendronate taken weekly during flight and (2) an intravenous (IV) dose of zoledronic acid 4 mg, administered just once approximately 45 days before flight. The crewmember has a choice between taking oral alendronate or IV administered zoledronic acid. The rationale for including both alendronate and zoledronic acid is that two dosing options will: maximize crew participation, increase the countermeasure options available to crew surgeons, increase scientific opportunities, and minimize the effects of operational and logistical constraints. Operational and logistical constraints may favor one option versus the other; however, the purpose of this study is not to compare the two dosing options. Rather, the intent is to show that bisphosphonates plus exercise will have a measurable effect versus exercise alone in preventing space flight induced bone loss.

If shown to be an effective countermeasure to space flight-induced bone loss, bisphosphonates could prevent or ameliorate several potential bone-related problems identified in NASA’s Bioastronautics Roadmap. In addition, if bisphosphonates improve the efficiency of in-flight exercise to maintain bone mass, then more crew time could be made available to improve other problem areas.

Primary Objective:

Determine the treatment effect of bisphosphonates [alendronate or zoledronic acid plus in-flight exercise (AL+EX, ZO+EX)] versus in-flight exercise alone (EX) on space flight induced bone loss. Measurements required: Percent change in femoral Quantitative Computed Tomography (QCT) values (volumetric trabecular Bone Mineral Density (BMD) of total hip, pre-flight versus R+5).

Secondary Objectives:

  • Determine treatment effect on Dual Energy X-Ray Absorptiometry (DXA) BMD of the hip, spine, pelvis and heel.
  • Determine treatment effect on QCT femur neck, hip trochanter trabecular BMD, and strength indices of the hip.
  • Determine treatment effect on Peripheral Quantitative Computed Tomography (pQCT) trabecular BMD and strength-strain-index of the tibia and wrist.
  • Determine the time course of changes to bone and bone regulatory systems in crewmembers taking alendronate/zoledronic acid (pre-flight, in-flight, and post-flight). Measurements will include pre- and post-flight serum markers of bone metabolism; pre-, in- and post-flight urinary markers of bone metabolism; pre and post-flight BMD.
  • Attempt to understand the underlying mechanism of changes to bone and bone regulatory systems caused by taking alendronate/zoledronic acid in microgravity. Measurements will include pre- and post-flight serum markers of bone metabolism; pre-, in- and post-flight urinary markers of bone metabolism.

++ -- View more

Leblanc A, Matsumoto T, Jones J, Shapiro J, Lang T, Shackelford L, Smith SM, Evans H, Spector E, Ploutz-Snyder R, Sibonga J, Keyak J, Nakamura T, Kohri K, and Ohshima H. Bisphosphonates as a supplement to exercise to protect bone during long-duration spaceflight. Osteoporosis International. 2013. July; 24(7):2105-14. []

Bone demineralization, pathologic
Bone density
Bone remodeling
Bone resorption
++ -- View more

Photo Gallery
+ View digital images

Data Information
Data Availability
Archiving in Progress. Some restricted access data exist for this experiment.
Data Sets+ Request data

1,25(OH)2 Vitamin D
25(OH) Vitamin D
Alkaline phosphatase
Body mass
++ -- View more

Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Expedition 18 10/12/2008 04/17/2009 187 days
Expedition 19 03/26/2009 10/11/2009 199 days
Expedition 20 05/27/2009 10/11/2009 137 days
Expedition 21 10/11/2009 12/01/2009 51 days
Expedition 22 11/30/2009 03/18/2010 109 days
Expedition 23 03/18/2010 06/01/2010 75 days
Expedition 25 09/24/2010 11/25/2010 31 days
Expedition 26 11/26/2010 03/16/2011 111 days
Expedition 27 03/14/2011 05/23/2011 70 days
Expedition 28 05/23/2011 09/15/2011 115 days
Expedition 29 09/16/2011 11/21/2011 40 days
Expedition 31 04/27/2012 07/01/2012 65 days
Expedition 34 11/18/2012 03/15/2013 117 days
Expedition 35 03/15/2013 05/13/2013 58 days
Expedition 36 05/13/2013 09/10/2013 166 days
Expedition 37 09/10/2013 11/10/2013 61 days
Expedition 38 11/10/2013 03/10/2014 120 days
Expedition 39 03/10/2014 05/13/2014 64 days
Expedition 40 05/13/2014 09/10/2014 133 days
Expedition 41 09/10/2014 11/09/2014 29 days
Expedition 42 11/10/2014 03/11/2015 121 days
Expedition 43 03/11/2015 06/10/2015 91 days
Expedition 44 06/10/2015 09/11/2015 93 days
Expedition 45 09/11/2015 12/11/2015 91 days
Expedition 48 06/18/2016 09/06/2016 80 days
Expedition 49 09/06/2016 10/30/2016 54 days

Human Research Program (HRP) Human Research Roadmap (HRR) Information
Crew health and performance is critical to successful human exploration beyond low Earth orbit. The Human Research Program (HRP) investigates and mitigates the highest risks to human health and performance, providing essential countermeasures and technologies for human space exploration. Risks include physiological and performance effects from hazards such as radiation, altered gravity, and hostile environments, as well as unique challenges in medical support, human factors, and behavioral health support. The HRP utilizes an Integrated Research Plan (IRP) to identify the approach and research activities planned to address these risks, which are assigned to specific Elements within the program. The Human Research Roadmap is the web-based tool for communicating the IRP content.

The Human Research Roadmap is located at:

+ Click here for information of how this experiment is contributing to the HRP's path for risk reduction.

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Jessica Keune
Institutional Support
National Aeronautics and Space Administration (NASA)
Japan Aerospace Exploration Agency (JAXA)