An evidence-based method for assessing the viability of denosumab as a countermeasure against microgravity-induced osteopenia
Abstract
One of the greatest concerns for human health during a long-duration mission is the loss of bone density, known as osteopenia, due to microgravity. Osteopenia increases the risk of fractures and limited mobility, which puts individual productivity and mission objectives at risk. Denosumab, a human monoclonal antibody, is commonly used to treat osteoporosis and bony metastases on Earth. This paper reviews current literature on the use of denosumab in space and, based on this literature, proposes a design of a two-part study to assess the viability of denosumab as a countermeasure against microgravity-induced osteopenia in comparison with exercise alone and with alendronate, a more widely used drug for osteoporosis. The first part of the study assesses whether denosumab is suitable for long-duration spaceflight at all. Factors to be considered include whether the space radiation environment affects the stability of denosumab, and whether current dosing regimens are mass and cost effective. The second part assesses the efficacy on astronauts as a direct comparison to existing countermeasures, such as exercise and alendronate. In-flight biochemical analysis would measure serum concentrations of parathyroid hormone (PTH), calcium, phosphate, vitamin D and alkaline phosphatase (ALP) of subjects that did exercise alone, exercise with denosumab and exercise with alendronate. Post-flight biochemical analysis and bone densitometry is also proposed. Several challenges exist with this study. Firstly, analysis of non-medical parameters such as mass, cost, risk and sustainability are considered but not thoroughly analysed. Also, the literature suggests that denosumab may interfere with the immune system, which is already suppressed in space due to physical and psychological stressors. Additionally, during the period over which the study would occur, new developments in drug research may alter the current understanding of denosumab. Regardless, the research methods and findings from this paper would not be obsolete, but rather, they would be applicable to similar studies on other drugs.
- Publication:
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43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E2030T