RESUMEN
Proteins, peptides, colloids, and polymers present a rapidly growing field of pharmaceutical industry. Bringing these products into market, however, is a huge regulatory challenge, especially because many of these therapeutics are intended for parenteral administration. Physicochemical properties of such products--size, shape, surface potential, and extent of particle-particle interaction-have to be well understood and monitored throughout manufacturing, release, and stability testing. First and foremost, size distribution of subvisible particles (SVP) in these products should be reliably measured. We present development of a flow imaging method to assess SVP in the polypeptide injectable therapeutic product-glatiramer acetate (Copaxone(®)). Flow imaging comprises optical inspection of a flowing liquid and allows quantitation of particles in the range of 1-500 µm. The challenges of method development are discussed and the method performance characteristics--accuracy, precision, linearity, and specificity--are demonstrated.