The effects of weightlessness on the human body are under constant study. Certain effects appear with every space flight on every crewmember, such as a headward fluid shift and muscle deconditioning. Other effects, however, are not consistent and do not always occur. A few of these include nausea, headache, backache, congestion and insomnia. Astronauts take medicine to alleviate the pain or discomfort caused by the body's adaptation to space. Pharmacology is the science concerned with drugs; space pharmacologists study how weightlessness may affect the appearance, chemistry, actions or uses of drugs.

Medications have been approved on all US space flights, although crewmembers are encouraged to consult with the flight surgeon before taking any drugs. Medications carried on Space Shuttle missions have varied somewhat from flight to flight, depending on the individual needs of the crewmembers. Medication use during Shuttle flights seems to be more prevalent than during earlier programs, perhaps because drugs are provided in easy-to-use forms. During the early Mercury flights, the drugs provided (most were for motion sickness and pain) were put into an injector system in order to allow the astronaut to deliver medication through the space suit into the thigh muscle. None of the injectors were used during flight until the sixth and last Mercury mission. That pilot became the first astronaut to take medication during space flight, when he took D-amphetamine tablets for motion sickness.

The difficulties involved in conducting definitive studies of the effectiveness of drugs during space flight have been compounded by the absence of a systematic approach to determining which drugs were taken by whom and under what circumstances. Attempts have been made to address this problem by holding confidential medical conferences on a regular basis between each crewmember and the flight surgeon, both during and after flight. Even with this approach, however, results are difficult to quantify. To better understand space pharmacology, scientists have developed a database which includes over 1500 reports of medication used during flight. The most frequent reasons for taking drugs in flight have been motion sickness (28%), headache (22%), insomnia (14%), congestion (12%) and back pain (8%).

Verifying the therapeutic effectiveness of medications that may be needed in the space flight environment is a crucial aspect of protecting crew health, particularly on long, remote missions. The multiple physiologic changes associated with space flight present a formidable challenge to this effort.


Experiments List:
Physiologic Alterations and Pharmacokinetic Changes during Space Flight


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Page last updated: 07/16/1999