Weighing Standard Ensures USP Compliance
On 3 June 2013, the United States Pharmacopeia (USP) published the revised mandatory Chapter 41 on balances as well as new updates to the advisory Chapter 1251. The new revisions define modified balance test procedures for the US pharmaceutical industry and also apply to companies exporting to the US. Mettler Toledo’s global weighing standard, GWP (Good Weighing Practice), can help pharmaceutical manufacturers and suppliers meet the new requirements. With the revised chapters becoming official on 1 December, 2013, Mettler Toledo is providing a free on-demand webinar at www.mt.com/gwp-usp-webinar to explain how balance quality management will be affected, focusing on the determination of minimum weight and execution of routine testing.
For a long time, balance users and manufacturers argued that balance assessment as per the USP’s General Chapter 41 (‘Balances’) was unclear and difficult to comply with. In addition, they frequently commented that General Chapter 1251 (‘Weighing on an Analytical Balance’) no longer represented state-of-the-art weighing practices. The revisions to both chapters in the Second Supplement to USP 36-NF 31 aim to help US pharmaceutical manufacturers and suppliers ensure accuracy and eliminate costly over-testing.
The new requirements of General Chapter 41 are mandatory. The revised chapter details a relatively demanding balance assessment, outlining accuracy and repeatability tests for calibrated balances used to weigh analytes for quantitative measures. Since accuracy can only be gauged using weights that are at least 5% of an instrument’s capacity, test weight selection criteria have also been modified accordingly (weights smaller than 5% cannot assess systematic deviations sufficiently well enough).
General Chapter 1251 provides additional clarification on the new procedures and extends the scope to any balance used for an analytical procedure. It details that balance performance verification should be carried out using a risk-based approach. Very importantly, it is recommended to only weigh net samples that weigh sufficiently more than the minimum weight to account for fluctuations in the balance’s performance owing to varying influences from the environment and the balance operators. This requirement is clearly applied to the sample weight itself and not to the tare vessel. Additionally and perhaps most importantly, daily testing recommendations have been dropped. This change is expected to provide significant time savings that, if accompanied by weighing accuracy, will offer monetary savings.
Although these revisions imply that unnecessary testing must be eliminated to protect manufacturing margins in today’s highly competitive pharmaceutical market, they continue to underscore that weighing accuracy is non-negotiable. Mettler Toledo’s GWP can help manufacturers implement the new USP regulations. Tailored to each weighing application, GWP Verification is a risk-based service that helps eliminate redundant or erroneous testing. Thanks to determining the minimum weight and measurement uncertainty for each and every balance and scale used in the weighing process, manufacturers not only optimise SOPs, ensure consistent product quality and pass air-tight audits, they also avoid potentially costly litigation and fines resulting from a poorly-formulated, out-of-specification product.
Mettler Toledo AG, Laboratory & Weighing Technologies, +41 44 944 22 11, marianne.portmann@mt.com, www.mt.com/gwp.