Variations in alkaloid content of herbal products containing goldenseal. 
To determine the concentration of hydrastine and berberine, the primary alkaloids in herbal products containing goldenseal.  Descriptive comparison of 20 products purchased at local pharmacies or health food stores; 17 products were labeled as containing goldenseal root and 3 products contained goldenseal herb as the sole active herbal ingredient.  Laboratory assessment of alkaloid content using high-performance liquid chromatography.  Comparisons of hydrastine and berberine concentration, alkaloid ratio, and total alkaloid content among products.  Hydrastine concentration in products labeled as containing goldenseal root ranged from 0 to 2.93%, whereas berberine concentration varied from 0.82% to 5.86%.  Median total alkaloid concentration was 5.30%.  Only 10 of 17 products met proposed United States Pharmacopeia (USP) standards for the hydrastine and berberine content of goldenseal root.  Five products contained little or no hydrastine, unusual berberine:hydrastine ratios, and additional peaks not observed with other products.  Alkaloid content in goldenseal root products was about fourfold higher than in products labeled as containing goldenseal herb.  Alkaloid content of goldenseal products varies widely, with many products failing to meet proposed USP standards.  In addition, the chromatographic pattern and alkaloid ratio for several products were atypical for goldenseal.  Given the current absence of regulation of the quality of herbal products, pharmacists should take extra care to ensure that substandard goldenseal products are not sold in their pharmacies.