title: Midodrine prescribed to improve recurrent post-spaceflight orthostatic hypotension.
abstract: Many astronauts exhibit post-spaceflight orthostatic hypotension due to inadequate norepinephrine release when in an upright posture. We hypothesized that an alpha1-adrenergic agonist, midodrine, would be an effective countermeasure. A female astronaut, who had problems with postflight orthostatic hypotension after a previous flight, consumed 10 mg midodrine after a subsequent flight, prior to her tilt test. Hemodynamic variables were compared between the two flights. Midodrine prevented severe falls in stroke volume, cardiac output and systolic pressure, and severe increases in heart rate without increasing vascular resistance, thus preventing orthostatic hypotension. This is the first report showing that midodrine has the potential to improve post-spaceflight orthostatic hypotension and suggesting that reduced venous return contributes to the etiology.
authors.affiliation: Universities Space Research Association, Houston, TX, USA.
authors.forename: Steven H
authors.initials: SH
authors.lastname: Platts
authors.forename: Michael G
authors.initials: MG
authors.lastname: Ziegler
authors.forename: Wendy W
authors.initials: WW
authors.lastname: Waters
authors.forename: Brett M
authors.initials: BM
authors.lastname: Mitchell
authors.forename: Janice V
authors.initials: JV
authors.lastname: Meck
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology / Q000627:therapeutic use*; D002302:Cardiac Output / Q000187:drug effects; D005260:Female; D006339:Heart Rate; D006801:Humans; D007024:Hypotension, Orthostatic / Q000188:drug therapy*; D008879:Midodrine / Q000494:pharmacology / Q000627:therapeutic use*; D012008:Recurrence; D013026:Space Flight; D013318:Stroke Volume / Q000187:drug effects
chemical_list: D000316:Adrenergic alpha-Agonists; D008879:Midodrine