Pharmacokinetics and locomotor activity increasing effect of ephedrine in mice

Ephedrine has stimulating effects on the CNS which have been shown as increased locomotor activity, for example. No studies on the relationship between this pharmacological effect and blood levels of the drug have been reported. In the present study this question was investigated in mice after intravenous and oral administration of ephedrine. It was concluded that after intravenous injection of ephedrine the blood concentration data fitted best with the two-compartment open model but after oral administration of the drug with the one-compartment model. The locomotor activity stimulating effect of the drug did not have a linear relationship to the drug levels in the central or in the tissue compartment. This suggests that the mechanism of the locomotor activity increasing effect of ephedrine is indirect.