Ephedrine pharmacokinetics after the ingestion of nutritional supplements containing Ephedra sinica (ma huang).

Nutritional supplements containing Ephedra sinica (ma huang), a botanical source of ephedrine alkaloids, have been linked to several episodes of ephedrine toxicity and at least 17 deaths, yet these products remain unregulated. Ten subjects were enrolled in a randomized, crossover study aimed at characterizing the pharmacokinetics of ephedrine after the ingestion of three commercially available ma huang products compared with a 25-mg ephedrine capsule. Pharmacokinetic parameters for botanical ephedrine were similar to those for synthetic ephedrine hydrochloride. Gender-based comparisons of Vss/F and CL/F revealed higher values for women than for men (Vss/F, 3.49 +/- 1.04 vs 2.98 +/- 0.73 l/kg; CL/F, 0.48 +/- 0.11 vs 0.37 +/- 0.11 l/hour x kg). The current study suggests that the increased incidence of ma huang toxicity does not stem from differences in the absorption of botanical ephedrine compared with synthetic ephedrine; rather, it results from accidental overdose often prompted by exaggerated off-label claims and a belief that "natural" medicinal agents are inherently safe.