A RETROSPECTIVE STUDY OF PROMETHAZINE AND ITS FAILURE TO PRODUCE THE EXPECTED INCIDENCE OF SEDATION DURING SPACE-FLIGHT

Since March 1989, intramuscular (IM) promethazine has been successfull y used to treat the symptoms of space motion sickness. The incidence o f sedation associated with promethazine administration on the ground i s large and may result in operational impact. The authors undertook a retrospective study to quantify the incidence of sedation from prometh azine use during Space Shuttle flights. Crew medical debriefings from 14 shuttle missions were reviewed for crew members who had been treate d with IM promethazine and their corresponding symptoms were identifie d. Twenty-one crew members received IM promethazine (25-50 mg), and on ly one experienced any associated sedation with no operational impact. This sedation incidence of less than 5% is in stark contrast to the 6 0 to 73% incidence of sedation seen in ground-based studies. The incid ence of sedation during space flight from IM promethazine is substanti ally less than that seen on the ground and does not present an operati onal problem during Space Shuttle flights. Future investigations of en vironmental stressors and pharmacodynamic changes associated with spac e flight may explain the huge disparity between the space-flight and g roundbased data.