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In-flight Use of Florinef to Improve Orthostatic Intolerance Postflight (DSO 621)
Principal Investigator
Research Area:
Cardiovascular physiology
Renal, fluid and electrolyte physiology
Species Studied
Scientific Name: Homo sapiens Species: Human

Hypovolemia may be one cause of the orthostatic intolerance that is common after space flight. Space flight is known to cause a shift in fluid away from the lower body and a decrease in body fluid. These effects are also produced by head-down tilt bed rest. Fludrocortisone (Florinef) is a drug that increases plasma volume by causing the kidneys to retain sodium. It has shown some ability to restore plasma volume and orthostatic tolerance after bed rest. However, the absorption of a drug may be altered in microgravity, and a dosage regimen that is effective on the ground may not be effective in space. The objective of this study was to test the use of fludrocortisone during space flight to expand plasma volume and improve postflight orthostatic tolerance, comparing three dosage regimens.

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Charles JB, Fritsch-Yelle JM, Whitson PA, Wood ML, Brown TE, Fortner GW. Cardiovascular deconditioning. In: Sawin CF, Taylor GR, Smith WL, editors. Extended Duration Orbiter Medical Project Final Report 1989-1995. Houston: NASA Johnson Space Center, 1999:1-1-1-19.

Shi SJ, South DA, Meck JV. Fludrocortisone does not prevent orthostatic hypotension in astronauts after spaceflight. Aviat Space Environ Med. 2004 Mar;75(3):235-9.[]

Blood pressure
Heart rate
Hypotension, orthostatic
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Data Information
Data Availability
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Body weight
Cardiac output
Diastolic blood pressure
Epinephrine, plasma
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Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
STS-45 03/24/1992 04/02/1992 9 days
STS-49 05/07/1992 05/16/1992 9 days
STS-50 06/25/1992 07/09/1992 14 days
STS-52 10/22/1992 11/01/1992 10 days
STS-55 04/26/1993 05/06/1993 10 days
STS-56 04/08/1993 04/17/1993 9 days
STS-64 09/09/1994 09/20/1994 11 days
STS-66 11/03/1994 11/14/1994 11 days
STS-67 03/02/1995 03/18/1995 17 days
STS-68 09/30/1994 10/11/1994 11 days
STS-70 07/13/1995 07/22/1995 9 days
STS-73 10/20/1995 11/05/1995 16 days
STS-74 11/12/1995 11/20/1995 8 days

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Pamela A. Bieri
Institutional Support
National Aeronautics and Space Administration (NASA)