Introduction

Pharmacologic therapy is a cornerstone of medical treatment of many diseases on earth. Thus, it should come as no surprise that medicines have been supplied for astronaut and cosmonaut spaceflight health needs since the dawn of the space age.

The unique aspects of the spaceflight environment raise many questions regarding the influence of microgravity (also referred to as "weightlessness" or "free-fall") on drug pharmacokinetics and pharmacodynamics. However, our collective knowledge of the effects of microgravity on pharmacotherapeutics is woefully lacking despite 50 years of experience with manned spaceflight.

Knowledge of optimal drug regimens in microgravity will be critical to ensure safe, effective, and definitive treatment of space travelers. As humans establish more permanent residence in space and embark on interplanetary exploration, they will certainly experience severe injury and illness that require definitive care, including drug treatment. As mission duration increases beyond 2-week space shuttle missions to journeys of 6 months or longer (as on the international space station) and interplanetary travel to Mars or near-earth asteroids (which would entail months to years of travel), increasing attention to pharmacologic countermeasures for mitigating the long-term medical consequences of spaceflight will be required. Bone loss,[1,2] muscle loss,[3,4] immune function changes,[5] and radiation exposure[6] are only a few of the physiologic issues affected by prolonged exposure to microgravity that will need to be addressed.

This article provides a broad overview of the influence of microgravity on human pharmacotherapeutics, including discussion of areas in which more research is needed.