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STERILIZATION. The complete destruction of all living organisms and their spores or their complete removal from the formulation. All parenterals, as well as otic, nasal, ophthalmic solutions, must be sterile, includes packaging materials methods steam dry-heat filtration gas
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STERILIZATION • The complete destruction of all living organisms and their spores or their complete removal from the formulation. • All parenterals, as well as otic, nasal, ophthalmic solutions, must be sterile, • includes packaging materials • methods • steam • dry-heat • filtration • gas • ionizing radiation CHEE 440
Viruses CHEE 440
Bacteria CHEE 440
Bacterial Endospores CHEE 440
Yeast and Mould aspergillus penicillium CHEE 440
Sterilization Methods • steam sterilization • conducted in an autoclave • method of choice • 121 C, 20 minutes • dry heat • less effective than moist heat • 170 C, > 2 hours • used to sterilize equipment CHEE 440
Heat Resistances • method determined by nature of micro-organism and formulation ingredients • protocols are developed based on reference organisms of known sterilization resistance • micro-organisms possess different resistances to heat CHEE 440
Steam Sterilization • Determination of steam sterilization protocol • first select a reference organism • determine its D value under defined conditions • establish initial bioburden • calculate time of exposure at 121 ºC CHEE 440
Sterilization Methods • Filtration • used for heat sensitive solutions • pore sizes range from 14 to 0.025 mm • Gas sterilization • used in hospitals and industry for thermolabile materials • ethylene oxide, propylene oxide used • 500-1000 mg/L, 4 - 16 hours at 55 ºC, 50-60 %RH • need to remove absorbed gas after sterilization • Ionization • use of gamma rays • limited application CHEE 440
Kinetics of Cell Inactivation • death rate follows first order kinetics CHEE 440
D value • decimal reduction time • time required for 90% reduction in cell count CHEE 440
Z value • degrees of temperature/dose change required to achieve a tenfold decrease in D CHEE 440
Example • Using G. stearothermophilus as a reference organism (D121 = 1.5 min), and an initial bioburden of 1000 spores, determine the sterilization time required to achieve a 1 in 1,000,000 chance of a spore surviving using a steam autoclave. CHEE 440
De-pyrogenation • Emphasis is placed on prevention of introduction of pyrogens • Removal • glassware, metals • 250 ºC for 45 minutes • water • oxidation to nonvolatile solvents using potassium permanganate, then distill • reverse osmosis • plastics • protect against contamination CHEE 440