Clinical Pharmacology of Spaceflight

Eleanor A. O'Rangers, PharmD

Disclosures

January 03, 2011

In This Article

Other Limitations and Conclusion

Planning and conducting experiments in space presents several practical challenges. Prioritizing the schedules of one experiment against another, higher-profile experiment on a flight manifest; training the crew to conduct the experiments (much less getting them to volunteer!); overcoming career astronauts' reluctance to report medical events; and working around miscellaneous crew activities, sleep, exercise schedules, and routine medication use (eg, for motion sickness or sleep) all make data collection difficult. Ground-based studies -- either human bed rest studies or animal work studies-- are imperfect analogues at best and have resulted in conflicting data compared with other ground-based studies and spaceflight studies. The end result is that conclusive data on drug pharmacokinetics and dynamics are limited. Definitive recommendations for medication use in space are, therefore, impossible to make at this time.

The essence of the multifactorial issues that prevent adequate characterization of drug efficacy in space was captured in a list of information gaps identified by the Science Advisory Team, within the Human Health Countermeasures element of NASA's Human Research Program (Table 5).

Table 5. Issues Affecting Characterization of Drug Efficacy in Space

1. Inadequate tracking of medication use, indication, efficacy, and side effects
2. What drug interactions of medications...will adversely affect clinical care?
3. What training methods and reference documents should be used for training the crew and medical team to identify and mitigate side effects and interactions of commonly used medications?
4. What diagnostic, therapeutic, and laboratory technologies are necessary to predict and manage medication side effects, interactions, and toxicity during spaceflight?
5. In-flight therapeutic drug monitoring is not compatible with current technology
6. Develop standard procedures for prospective analyses of drugs considered for flight and periodic analyses of drugs that are used for flight
7. What are the effects of spaceflight on pharmacokinetics and pharmacodynamics?
8. What better ways can be found to administer drugs to provide more rapid and reliable treatment with minimal side effects (eg, intranasal, microencapsulation, drug cocktails)?
9. What is the effect of long-term spaceflight on drug stability, and what measures can be taken to extend the duration of drug efficacy?
10. What are the performance effects of in-flight drugs on exercise, orthostatic tolerance, motor control, and cognitive function?
Adapted from NASA Human Research Program[10]


Medical events among astronauts are common, and medication use is frequent. Unfortunately, our knowledge of drugs and their interaction with the human body in space (space pharmacology) is in its infancy. Very limited data suggest that drugs are handled differently by the body in microgravity than on earth. Drug stability and drug delivery are also issues to overcome; these have important implications for drug dosing, efficacy, and safety.

As humans establish more permanent residence in space and embark on interplanetary exploration, injury and illness that will require definitive care, including drug treatment, will occur. Knowledge of optimal drug regimens in microgravity will be critical for ensuring safe, effective, and definitive treatment.

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