Using ICP-MS to Measure Elemental Compositions in Drug Products

pharmaceutical products. They can derive from raw materials, active pharmaceutical ingredients (APIs), formulation agents, solvents, reactors, catalysts, transferring pipelines, and other equipment used during production. The United States Pharmacopeia (USP) identified and set limits on the concentration of several elements in pharmaceuticals and categorized them into three classes based upon their toxicity and chance of detection in the final drug product. The Class 1 elements include As (arsenic), Hg (mercury), Cd (cadmium), and Pb (lead); also known as the “Big Four”, these elements are known or strongly suspected human toxicants and thus should be essentially absent (<1 μg/day). The Class 2 elements, Co (Cobalt), V (vanadium), Ni (nickel), Tl (thallium), Au (gold), Pd( palladium), Ir (iridium), Os (osmium), Rh (rhodium), Ru (ruthenium), Se (selenium), Ag (silver), Pt (platinum) , along with Class 3 elements Li (lithium), Sb (antimony), Ba (barium), Mo (molybdenum), Cu (copper), Sn (tin), Cr (chromium) are slightly less toxic than the Big Four, though still run the risk of appearing in final drug formulations. These impurities can also affect the stability and shelf life of drugs because of their catalytic activities. This is true for oral drugs (e.g., vitamins), inhalation drug products (e.g., bronchodilators to alleviate asthma), and topical formulations (any product applied to the skin).²