title: Midodrine prevents orthostatic intolerance associated with simulated spaceflight.
abstract: Many astronauts after being weightless in space become hypotensive and presyncopal when they assume an upright position. This phenomenon, known as orthostatic intolerance, may interfere with astronaut function during reentry and after spaceflight and may limit the ability of an astronaut to exit a landed spacecraft unaided during an emergency. Orthostatic intolerance is more pronounced after long-term spaceflight and is a major concern with respect to the extended flights expected aboard the International Space Station and for interplanetary exploration class missions, such as a human mission to Mars. Fully effective countermeasures to this problem have not yet been developed. To test the hypothesis that alpha-adrenergic stimulation might provide an effective countermeasure, we conducted a 16-day head-down-tilt bed-rest study (an analog of weightlessness) using normal human volunteers and administered the alpha(1)-agonist drug midodrine at the end of the bed-rest period. Midodrine was found to significantly ameliorate excessive decreases in blood pressure and presyncope during a provocative tilt test. We conclude that midodrine may be an effective countermeasure for the prevention of orthostatic intolerance following spaceflight.
authors.affiliation: Department of Anesthesia and Critical Care, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
authors.forename: C D
authors.initials: CD
authors.lastname: Ramsdell
authors.forename: T J
authors.initials: TJ
authors.lastname: Mullen
authors.forename: G H
authors.initials: GH
authors.lastname: Sundby
authors.forename: S
authors.initials: S
authors.lastname: Rostoft
authors.forename: N
authors.initials: N
authors.lastname: Sheynberg
authors.forename: N
authors.initials: N
authors.lastname: Aljuri
authors.forename: M
authors.initials: M
authors.lastname: Maa
authors.forename: R
authors.initials: R
authors.lastname: Mukkamala
authors.forename: D
authors.initials: D
authors.lastname: Sherman
authors.forename: K
authors.initials: K
authors.lastname: Toska
authors.forename: J
authors.initials: J
authors.lastname: Yelle
authors.forename: D
authors.initials: D
authors.lastname: Bloomfield
authors.forename: G H
authors.initials: GH
authors.lastname: Williams
authors.forename: R J
authors.initials: RJ
authors.lastname: Cohen
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000627:therapeutic use*; D000328:Adult; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology / Q000517:prevention & control; D001510:Bed Rest; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007024:Hypotension, Orthostatic / Q000503:physiopathology / Q000517:prevention & control*; D008297:Male; D008879:Midodrine / Q000627:therapeutic use*; D018561:Space Simulation; D018667:Tilt-Table Test
chemical_list: D000316:Adrenergic alpha-Agonists; D008879:Midodrine