Content versus label claims in ephedra-containing dietary supplements.

The content of ephedra alkaloids in herbal dietary supplements containing ephedra (ma huang) was studied. The ephedra alkaloid content of 20 ephedra-containing supplements was determined by high-performance liquid chromatography. Contents of (-)-ephedrine, (+)-pseudoephedrine, (-)-methylephedrine, (-)-norephedrine, and (+)-norpseudoephedrine were measured. Ephedra alkaloid content varied considerably among products. Total alkaloid content ranged from 0.0 to 18.5 mg per dosage unit. Ranges for (-)-ephedrine and (+)-pseudoephedrine were 1.1-15.3 mg and 0.2-9.5 mg, respectively. (+)-Norpseudoephedrine, a Schedule IV controlled substance, was often present. Significant lot-to-lot variations in alkaloid content were observed for four products. For one product, lot-to-lot variations in the content of (-)-ephedrine, (+)-pseudoephedrine, and (-)-methylephedrine exceeded 180%, 250%, and 1000%, respectively. Half of the products exhibited discrepancies between the label claim for ephedra alkaloid content and actual alkaloid content in excess of 20%. One product was devoid of ephedra alkaloids. Assay of 20 ephedra-containing dietary supplements showed that alkaloid content often differed markedly from label claims and was inconsistent between two lots of some products.