STERILITY the complete destruction of all living organisms and their spores or their complete removal from the formulation all parenterals must be sterile, as well as otic, nasal, ophthalmic solutions includes packaging materials methods steam dry-heat filtration gas ionizing radiation

Sterilization steam sterilization dry heat method determined by nature of micro-organism and formulation ingredients protocols are developed based on reference organisms of known sterilization resistance 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

Heat Resistances micro-organisms possess different resistances to heat

Filtration used for heat sensitive solutions pore sizes range from 14 to 0.025 mm advantages fast for small volumes effective for thermolabile materials inexpensive removes other particulate matter disadvantages possibility of tears in membrane comparatively slow for large volumes

Sterilization Methods 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

Kinetics of Cell Inactivation death rate follows first order kinetics guaranteed sterility would require an infinite time D value decimal reduction time time required for 90% reduction in cell count Z value degrees of T change required to achieve a tenfold decrease in D

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

Example Using B. stearothermophilus as a reference organism (D121 = 0.5 min), and an initial bioburden of 100 spores, determine the sterilization time required to achieve a 1 in 100,000 chance of a spore surviving using a steam autoclave.

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