Sterilization of glycerin

Abstract

The sterilization of glycerin is described. Glycerin is used in a wide variety of pharmaceutical formulations, including oral, otic, ophthalmic, topical, and parenteral preparations. Of the myriad uses for glycerin, some require a sterile solution. Due to the nature of dry heat sterilization with resulting equipment and validation needs, sterile filtration is the preferred sterilization method for glycerin at the Mayo Clinic Pharmacy Services Production Laboratory in Rochester, Minnesota. A practical procedure was attained with the use of a chemically compatible 0.22-microm capsule filter, peristaltic pump, and sterile tubing. The sterile tubing is attached firmly, with a twisting motion, to the hose barb ends of the filter. The peristaltic pump is set at minimum speed, and a sterile syringe is used to capture the sterile glycerin filtrate. After filtration, filter integrity testing using the bubble point test is performed on the filter used to sterilize the solution. Packaging was then completed by placing glycerin aliquots into unit-of-use sterile syringes, placing a sterile tip cap on each syringe, and labeling the syringe. End testing is needed for preparations, such as sterile glycerin, that are made from nonsterile components, regardless of sterilization technique. This quality-control testing includes but is not limited to visual checks, pH checks, and tests for bacterial endotoxins, particulate matter, and sterility. Beyond-use dating is then assigned based on chemical, physical, microbiological, and packaging considerations. A practical method for sterilization of glycerin by compounding pharmacists is attainable through the use of membrane filtration. Sterility assurance is achieved through appropriate validation, and quality-control checks must be completed before release of the injectable preparation.