Microgravity-Induced Alterations in Drug Pharmacokinetics: Implications for Space Medicine

Space flight poses distinct challenges for human physiology and environment that might result in significant changes in pharmacokinetics (PK) of drugs that could affect safety and efficacy of pharmacotherapy in space. Microgravity causes alteration in body fluid shifts, cardiovascular system, gastroenterology, liver, kidney and body composition function thus affecting processes of drug absorption, distribution, metabolism and elimination (ADME). Moreover, space radiation and drug storage can impair the stability of the drugs thus affecting performance of the medications. The purpose of the current review is to explore the influence of microgravity on the pharmacokinetics of drugs and to evaluate the implications of this effect for pharmacotherapy during human space flight based on space flight, analogs, and recent research findings. Existing research indicates that space flight-related adaptation may result in clinically meaningful changes in the PK of the drugs; however, the magnitude of this impact is unknown because of limited data from human space flight as well as methodological variability in the available studies.