Correspondence                                                                                                      Spaceflight Vol 47 October 2005, P 390

 

Space tourism and pharmaceuticals


                           

 Sir, Space tourism is around the corner and ultimately an orbital hotel will be an inviting goal for some middle-aged adventurers with deep pockets. The downside with aging is of course the potential health price but there is some increased vascular risk even by age 30, since by this time there is some impairment in the repair process of the lining of the blood vessels (endothelium) [1] triggering injuries, often unrecognized, even with treadmill stress tests. Furthermore, after just 12.5 days in space, experimental animals show injuries of the endothelium [2].

    There is at least a 25 percent incidence ‎of hypertension in those without known heart disease in our advanced society by age 35 [3]. This predisposes to a variety of vascular complications, potentially emergent. How complacent can a space tourist be, that one's anti-hypertensives will prevent these complications during the flight particularly during the stress of re-entry even though ‎the G forces would be less than half the re­entry 7 Gs of the Apollo space missions? [4]

 Furthermore. pharmaceuticals may not be adequately absorbed by mouth because malabsorption is an invariable complication of microgravity [5]. Also will the invariable dehydration of space flight [6] prevent hypertension as effectively as a diuretic? In the presence of malabsorption, how reliable would daily ingestion of  aspirin be in ‎preventing blood clots, triggered by these potential insults to the endothelium? How ‎can one be sure that pharmaceuticals - ‎even if adequately absorbed - will be effective, in the presence of deterioration of some pharmaceuticals in space [7] which may be secondary to radiation effects (personal communication, L. Putcha)? It may be argued that 77-year-old John Glenn had no apparent cardiovascular problems on his 10 day space mission in 1998, but to my knowledge, NASA has not published the results of any medical studies regarding this.

William J. Rowe MD
Virginia, USA

References

1. P.M, Vanhoutte, L.P. Perrault and J.P. Vilaine, Endothelial dysfunction and vascular disease in: The endothelium In clinical practice.  G.M. Rubanyi and V.J. Dzau (eds). New York, Marcel Dekker Inc. 1997, pp.265-289.

2. D.E Philpott, A. Popova. J. Kato et al, Morphological and biochemical examination of Cosmos 1887 rat heart tissue: Part 1-­ultrastructure FASEB J. 4.1990, pp.73-78.

3. W.W. Yeo, K.R. Yeo, Coronary risk versus cardiovascular risk for treatment decisions in mild hypertension J Cardiovasc Risk 9, 2002.  pp 275-280.

4. W. J Rowe, Astronaut's heart problem. Spaceflight, 43.2001 p.83.

5. G L Amidon, GA De Brincat, N. Najib, Effects of gravity on gastric emptying, intestinal transit, and drug absorption J Clin Pharmacol. 31,  1991, pp 968-973.

6. WJ.Rowe. The Apollo 15 space syndrome, Circulation 97, 1998, pp. 119-120.


7. J. Du, T.M. Bayuse, V. Shah et. Al. Stability of ‎pharmaceuticals during space flight,  AAPS Pharm Sci 4,2002, Abstract T 3153.