Space motion sickness (SMS), therapy by astronaut profile
- Paper number
IAC-05-A1.1.09
- Author
Mr. Tom Ennekens, University of Antwerp, Belgium
- Year
2005
- Abstract
The human balance system is of great importance for well being on earth. Our eyes, inner ear and proprioceptive organs in muscles, organs and joints provide a lot of information to our brain. If well processed it makes us able to move in a coordinated way in an orientated world with the possibility to fix objects on our retina.
In space there is a problem. In microgravity the system is unable to provide adequate information to the brain. The otoliths in the utriculus are unweighted and endolymphatic movements are disturbed.
Space motion sickness symptoms are similar to motion sickness on Earth. Although there is no diaphoresis, flushing is more common and vomiting frequently occurs without nausea or other warning.
About 70 percent of first-time space travellers develop the condition during the first few hours in space with symptoms peaking around 10 hours into the flight. The condition can recur when returning to Earth’s gravity.
Because of the importance of the problem many countermeasures have been suggested. Current NASA policy is to use promethazine (Phenergan) 50mg IM when SMS becomes a problem. Still there are difficulties with this generalised policy: - As described above, vomiting occurs often without warning. Wouldn’t prophylactic medication be better, or additive? - Despite promethazine treatment, SMS continues to be a problem for approximately 10- Promethazine produces sedation or drowsiness as a side effect. In case of emergency even a CNS stimulant must be used to overcome this.
Therefore it is of great importance that newer more specific drugs should be evaluated. It is obvious that vestibulosuppressants like meclizine, dimenhydrinate, droperidol, diazepam, lorazepam, alprazolam and scopolamine would be effective. Antihistamines as promethazine act as a receptor antagonist at multiple histamine (H1 and H2) receptors. Over the last decade, receptor antagonists specific for the H1 receptor have been developed, and it is likely that one of these (Zamifenacen) can be successfully used to counter SMS without drowsiness as a side effect. It may be that this drug, or one like it, is more efficacious for SMS for a larger percentage of the population.
At the University Hospital of Antwerp a test is used for measuring depressant effects of medication to the vestibular function. The slope of the linear regression is a measure of the responsiveness of both utricles. Most medications act in a different way. Particular this may be appropriate to use, because each astronaut will have a different profile of utricular response. In my opinion it may be beneficial to have an individual profile of each astronaut. A more personal therapy will have better results and less side effects, because the amount given can be tested on earth, as well as back-up therapy. In this way, prophylactic medication can be given in the beginning of space flight and by returning to earth. Even for more prolonged voyages with visits on different planets or objects and eventually space ship created artificial gravity, a particular scheme of therapy can be worked out.
- Abstract document
- Manuscript document
IAC-05-A1.1.09.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.