1. INTRODUCTION

Depyrogenation by filtration involves the physical removal of endotoxins from pharmaceutical solutions by adsorption and size exclusion. Endotoxins are responsible for making up the majority of pyrogens, which must be removed from pharmaceutical products including injectable biologics. There are many factors to be considered when designing a depyrogenation filtration process for solutions containing proteins and peptides: type of target protein and its concentration, electrolyte concentration, pH and buffer system, protein molecular weight and isoelectric point (pI), filtration parameters (e.g., flow rate), and interactions with other components causing aggregation. In general, a combination of these factors determines the most effective depyrogenation method.