A crescent-shaped spindle for improved dissolution testing.

Current practices of drug dissolution testing require that the experimental conditions, such as medium and its volume and apparatus and its associated stirrer rotation speed, be established for each test product to achieve certain 'expected' dissolution characteristics or results. In reality, however, the purpose of dissolution testing should be to determine potentially unknown dissolution results reflective of a test product based on its formulation and/or manufacturing attributes. For appropriate testing, in particular for comparative purposes, the experimental conditions must be the same or consistent from product to product i.e. product independent. This article describes a newly developed spindle, known as crescent-shaped, which can easily be installed in the vessel-based dissolution apparatuses (basket and paddle) to provide a product-independent dissolution testing approach for improved drug dissolution assessments. The new spindle provides an improved stirring and mixing environment, leading to better characterization of pharmaceutical products. The use of the crescent-shaped spindles offers additional significant advantages over the current practices, such as: (1) allows analyses using a single method, compared to hundreds as currently required, for both immediate and extended-released products having the same or different active ingredients; (2) provides improved dissolution characteristics of products by avoiding false slow release properties for fast release type products; (3) simplifies testing by avoiding the necessity of developing separate QC and bio-relevant dissolution methods; (4) provides a rugged testing environment free from common sensitivities, in particular to de-aeration and vibration effects. Considering that the new design provides significant advantages, the spindle may be considered for inclusion in the Ph. Eur., as an option, in the general chapter on dissolution testing.