Cm. Lathers et Jb. Charles, ORTHOSTATIC HYPOTENSION IN PATIENTS, BED REST SUBJECTS, AND ASTRONAUTS, Journal of clinical pharmacology, 34(5), 1994, pp. 403-417
Orthostatic hypotension after even short space flights has affected a
significant number of astronauts. Given the need for astronauts to fun
ction at a high level of efficiency during and after their return from
space, the application of pharmacologic and other treatments is stron
gly indicated. This report addresses the clinical problem of orthostat
ic hypotension and its treatments to ascertain whether pharmacologic o
r physiologic treatment may be useful in the prevention of orthostatic
hypotension associated with space flight. Treatment of orthostatic hy
potension in patients now includes increasing intravascular volume wit
h high sodium intake and mineralocorticoids, or increasing vascular re
sistance through the use of drugs to stimulate alpha or block beta vas
cular receptors. Earlier treatment used oral sympathomimetic ephedrine
hydrochloride alone or with ''head-up'' bed rest.(1) Then long-acting
adrenocortical steroid desoxycorticosterone preparations with high-sa
lt diets were used to expand volume. Fludrocortisone was shown to prev
ent the orthostatic drop in blood pressure.(2) The combination of the
sympathomimetic amine hydroxyamphetamine and a monoamine oxidase inhib
itor tranylcypromine(3) has been used, as has indomethacin alone.(4) D
avies et al.(5) used mineralocorticoids at low doses concomitantly wit
h alpha-agonists to increase vasocontrictor action. Schirger et al(6)
used tranylcypromine and methylphenidate with or without a Jobst elast
ic leotard garment or the alpha-adrenergic agonist midodrine (which st
imulates both arterial and venous systems without direct central nervo
us system or cardiac effects). Vernikos et al(7) established that the
combination of fludrocortisone, dextroamphetamine, and atropine exhibi
ted a beneficial effect on orthostatic hypotension induced by 7-day 6
degrees head-down bed rest (a model used to simulate the weightlessnes
s of space Fight), Thus, there are numerous drugs that, in combination
with mechanical techniques, including lower body negative pressure to
elevate transmural pressure, could be studied to treat orthostatic hy
potension after space flight.