Because of actual toxicological data, the importance of testing metal impurities in pharmaceutical preparations and biologically active food components (nutraceuticals) is increasing. Besides, this represents an important element of consumer protection.
For this reason, the implementation of pharmacopoeial methods on reliable limits based on the actual state of technology is essential.
In the USP, the official method to determine metals impurities doesn't meet this criterion anymore and is actually in revision. The analytical method is based on a colorimetric procedure which is not an element specific method, nor is it equally sensitive to each metal. A specific and reliable analytic procedure is important and the EMA Guideline "on the specification limits for residues of metal catalysts or metal reagents"(EMEA/CHMP/SWP/4446/2000) from 2008 lays down limits for the permitted daily exposure (PDE).
The analytical technology on element specific quantitative determination of metals have been existing for years, e.g. CVAA (Cold Vapor Atomic Absorption), ICP/OES (Inductively Coupled Plasma-Optical Emission Spectroscopy) or ICP/MS (Inductively Coupled Plasma-Mass Spectrometry) - but so far, it hadn't found any entry in the methods arsenal of pharmacopoeial tests. The USP initiative to revise Chapter <231> and make of it 2 chapters "USP<232>" and "USP<233>" should change this. The new monograph also requires the individual quantitative determination of metals with the highest toxicological risk - arsenic, cadmium, lead and mercury. The USP won't dictate any special analytical procedure but let the analytical laboratory choose the best suitable solution for the analytical issue in question.
The new USP chapters on testing metal impurities in medicinal preparations and food supplements should come into force by mid-2013. This means for companies concerned an instrumental upgrade of their QC laboratories but also considerable investment in sufficiently qualified personnel. After all, enhanced product quality as well as consumer and patient protection are the first priority.
Please also see the new chapters<232> "Elemental Impurities - Limits" and <233> "Elemental Impurities - Procedures".
Note: detecting metal impurities will be one of the topics dealt with during the ECA Conference "Impurities"taking place in Copenhagen, Denmark, from 23-25 May 2012.
Dr Gerhard Becker
CONCEPT HEIDELBERG (a service provider entrusted by the ECA Foundation)