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Effectiveness and duration of intramuscular antimotion sickness medications
C D Wood1, J J Stewart, M J Wood
1Department of Pharmacology, Louisiana State University Medical Center, Shreveport 71130.
Abstract:
Motion sickness inhibits gastric motility, making the oral route ineffective for medications. The intramuscular route is an effective alternative. The rotating chair was used to produce the M 111 level of motion sickness on the Graybiel Symptom Scale. The intramuscular medications given 30 minutes before rotation were compared with placebo (saline, 1 mL) for effectiveness and duration in increasing the number of tolerated head movements. Average placebo number of head movements was 294. Promethazine 25 mg increased head movements by 78% (P < .05), with a duration of 12 hours. Scopolamine 0.2 mg increased head movements by 91% (P < .05), with a duration of 4 hours. The effect of caffeine 250 mg and ephedrine 25 mg was not significant. When combined with scopolamine, ephedrine produced an 32% additive effect. Scopolamine 0.08 mg, 0.1 mg, and 0.2 mg and also promethazine 12.5 mg and 25 mg were significant (P < .05). Promethazine appears to be the drug of choice for intramuscular use because of a longer duration and a high level of effectiveness. Scopolamine was of high effectiveness, but had a duration of 4 hours. It was eight times as potent by the intramuscular as by the oral route.
Insights
Intramuscular medications effectively treat motion sickness when oral routes fail. Promethazine offers longer-lasting relief than scopolamine, making it a preferred choice for preventing nausea and vomiting.
Area of Science:
- Aerospace Medicine
- Pharmacology
- Human Physiology
Background:
- Motion sickness significantly impairs gastric motility, rendering oral medications ineffective.
- The intramuscular (IM) route presents a viable alternative for administering anti-motion sickness treatments.
- Understanding drug efficacy and duration via IM injection is crucial for managing motion sickness in challenging environments.
Purpose of the Study:
- To evaluate the effectiveness and duration of various intramuscular medications in preventing motion sickness.
- To compare the efficacy of promethazine and scopolamine against placebo in a controlled motion sickness model.
- To determine optimal dosages and identify potential synergistic effects of combined medications.
Main Methods:
- Inducing motion sickness using a rotating chair to achieve M 111 level on the Graybiel Symptom Scale.
- Administering intramuscular medications (promethazine, scopolamine, caffeine, ephedrine) 30 minutes prior to rotation.
- Comparing the number of tolerated head movements against a saline placebo (1 mL).
- Assessing the statistical significance (P < .05) and duration of drug effects.
Main Results:
- Placebo group tolerated an average of 294 head movements.
- Promethazine (25 mg) increased head movements by 78% with a 12-hour duration.
- Scopolamine (0.2 mg) increased head movements by 91% with a 4-hour duration.
- Caffeine and ephedrine showed no significant effect alone, but ephedrine demonstrated a 32% additive effect with scopolamine.
Conclusions:
- Intramuscular promethazine is recommended for motion sickness due to its high effectiveness and longer duration (12 hours).
- Intramuscular scopolamine is effective but has a shorter duration (4 hours), though it is significantly more potent than oral administration.
- Dosage-dependent effects were observed for both promethazine and scopolamine, with lower doses also proving significant.