Clinical Pharmacology of Spaceflight

Eleanor A. O'Rangers, PharmD


January 03, 2011

In This Article

Medication Use by Astronauts

Medications have been carried aboard US spacecraft since the inception of the Mercury program in the early 1960s. On the first 4 Mercury flights (May 1961 to May 1962), injector systems were developed to allow an astronaut to deliver medication through his spacesuit and directly into the thigh muscle. Three medications were carried via an injector: epinephrine (1:1000), cyclizine for motion sickness (45 mg/0.9 mL), and meperidine for pain (90 mg/0.9 mL). Dextroamphetamine tablets were also carried. On the fifth Mercury flight (October 1962), only cyclizine and meperidine were carried. For the sixth flight (May 1963), cyclizine and meperidine injections and dextroamphetamine tablets were supplied. (Information on why medications were changed between the various flights is unavailable.) Of note, during this last flight, Gordon Cooper was instructed to take dextroamphetamine before his reentry sequence for returning to earth; he thus became the first astronaut to ingest a medication in the US Space Program.[10,11,12]

For Project Gemini (April 1964 to November 1966), the medication kit was expanded to accommodate conditions that might occur with longer flight duration in earth orbit. It was also during this program that flight surgeons initiated a crude "test program" in which astronauts were administered each of the medications contained in the kit to observe their reactions to them. It was the opinion of the flight surgeons at the time that medications prescribed for use during the Gemini flights produced their desired effects. Flight surgeons additionally made some of the first routine countermeasure recommendations: Astronauts were instructed to take dextroamphetamine with a decongestant before reentry, and diphenoxylate was prescribed to prevent defecation during flight. Anti-motion sickness medication was prescribed in 1 instance before atmospheric reentry to reduce the possibility of motion sickness after splashdown.[13]

During Project Apollo, medical kits were stowed in both the command and lunar modules. Medications reported to have been taken most frequently by astronauts during 10 of these missions included oral doses of aspirin, acetaminophen, triprolidine, cyclizine, secobarbital, and diphenoxylate; oxymetazoline nasal spray was also used.[7]During the Apollo-Soyuz Test Project in 1975, quinidine and dipyridamole were added to the medical kit for 1 astronaut who had a history of cardiac rhythm disturbances.[14]

During the Mercury, Gemini, and Apollo missions, crew members were encouraged to consult with flight surgeons before taking any medications during flight, including over-the-counter medications. Unfortunately, systematic documentation of which medications were taken by whom and for what circumstance was never undertaken during these programs; moreover, records from Mercury flights and from 7 Gemini flights have been lost or destroyed.[15] On the basis of crew medical debriefings from early space shuttle missions, Tietze and Putcha[16] indicated that medication use is common during short-duration (2 weeks or less) space missions. It was speculated that medication use during the space shuttle program may have been more frequent owing to the convenience of dosage forms other than via injectors.[10] During the first 33 shuttle missions, 83% of crew members took medications at some time during the mission. In most cases, medications were taken to manage bothersome, non-life-threatening conditions associated with short-term adjustment to the microgravity environment, such as space motion sickness, back pain (from spinal cord expansion), nasal congestion and headache (from headward fluid shifts), and insomnia.

A more recent review of pharmaceutical use in the shuttle program found that at least 75% of astronauts had taken medication for similar nonemergency indications during their missions.[17] Medications aimed at ameliorating symptoms associated with adjustment to microgravity. are routinely available to astronauts primarily in oral dosage forms (tablets and capsules), but intramuscular injections, rectal suppositories, ocular preparations, and topical agents are also available in the on-board medical kit. Occasionally, certain medications are included in the medical kits to accommodate particular needs of specific crew members.[10]

Commenting on the occurrence of more significant in-flight emergency events that have occurred during longer stays in space, Summers and colleagues noted, "To date, the majority of space exploration has involved healthy young individuals (average age approximately 40 years; approximately 20% are female astronauts) who have undergoneintensive medical screening and remain in space for only short periods. In considering longer missions with more diverse crews, such as the extended occupancy of the International Space Station or a possible voyage to Mars, then it is increasingly important to plan for a medical emergency."[8] Not only is the probability of medical events (including serious or life-threatening emergencies) a call to increase the sophistication of medical treatment capabilities in space (which are currently limited), but the appropriate selection and supply of medications will be integral to crew healthcare management.


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