Dissolution testing of inhaled drugs is of significant interest to the developers of orally inhaled products (OIPs) that deposit solid particles in the lung. As yet, there is no regulatory requirement or established pharmacopoeial technique for such testing, but its relevance is clear; understanding and, in the longer term, learning to control the dissolution rate of an active (particularly one for systemic therapy) opens up the possibility of tailoring formulation properties, as well as dosing levels and frequencies, for improved drug efficacy and patient compliance.
Against this background, research has been conducted to establish a suitable method for dissolution testing of inhaled products. This paper considers the need for this and describes a technique developed at the University of Texas at Austin (TX, USA). Based on using standard USP dissolution test equipment for solid dosage forms, this new technique differentiates the solubility of OIPs.