Chlorpheniramine and ephedrine in combination for motion sickness

Chlorpheniramine is effective against motion sickness, but produces sedation. To reduce chlorpheniramine's sedating effect and increase its effectiveness, ephedrine was combined with chlorpheniramine to prevent motion sickness.

Chlorpheniramine (C) and chlorpheniramine plus ephedrine (Chlorphedra) were studied in a randomized, double blind, crossover trial. Eighteen normal subjects were randomized to six different orderings of placebo, C (12 mg) or Chlorphedra (12 mg C + 50 mg ephedrine). They ingested the medication 3.25 hours before off vertical axis rotation in a rotating chair. Cognitive testing with both objective and subjective tests was performed before drug ingestion, at peak drug effect and following rotation.

Both C and Chlorphedra significantly increased chair time compared to placebo [6.6 to 10.3 minutes (C), 10.2 minutes (Chlorphedra), p<0.01]. Subjects reported significantly more sleepiness on the Karolinska sleepiness scale after taking C (3.3 placebo, 4.9 C (p<0.005)) but not with Chlorphedra (3.3 placebo, 3.1 Chlorphedra). Chlorphedra resulted in significantly higher reported alertness, clearheadedness and attentiveness compared to C. Deficits seen on objective tests with C were corrected with Chlorphedra. Subjects noted more side effects with Chlorphedra.

Ephedrine does not increase the effectiveness of chlorpheniramine against motion sickness, but counteracts sedative and performance effects successfully.