Pharmacology of motion sickness.

Clinical trials of drugs are either operational conditions, parabolic flight. or rotation in a laboratory setting. Operational conditions include aerobatic flight. cruising small craft into ocean swells. transatlantic crossin~ by ship. OJ" maritime oreration~ Paraholic nighl descrihe~ 2( parabolas With g forcc~ i rom () let ] .S .. ~. common end point in sue\"' stLlcIie~ i '. \'(1m itin~ ~alo­ oratory tests include several variatiom on subjects seated in a chair that rotate~, while rhey make head movements in the four cardinal directions. The variations include alterations in the visual field, the use of different constant rates of rotation, or a progressive increase in the rate of rotation after each set of head movements. The end point is usually nausea. Squirrel monkeys of the Bolivian phenotype are tested in a rotating chair similar to that used -. . .. . . . RPM and adds a 15 cm sinusoidal vertical motion at 0.5 Hz (4). Suncus 11l1lrinus, an insectivore. is responsive to a reciprocating shaker. Motion is in the horizontal plane with excursions of 40 mm and a frequency of 1.0 Hz (48). Cats respond to sinusoidal vertical motion or a swing. The laboratory generating drug data uses a device similar to a Ferris wheel, differing mainly in that the subjects ride sideways rather than fore and aft (10). The cats are free to move in plexiglass boxes suspended from the ends of a 0.89 m horizontal beam. The beam rotates at the optimum frequency of 0.28 Hz (17 RPM), which is close to the human optimum of 0.2 Hz.