Permeability Package

For both methods, the duration of a suitably run test varies based on the results. For more permeable packages, a shorter test duration is permissible because larger mass changes are expected each day, which make small errors negligible. Less-permeable packaging systems will have smaller daily mass changes, so a small experimental error can be extrapolated to have a much larger effect on the result. Thus Class A containers should be assessed for at least four weeks. Class B containers for at least one week. Class C containers for at least two days, and Class D containers for at least one day. Acceptable permeation values are shown in Table 3. 

For pharmaceutical products in semi-permeable packaging material, the standard long-term stability testing condition has now been moved to 30°C/75% RH. 

Aqueous-based solutions in semi-permeable packaging, and dosage forms sensitive to low humidity, e.g., hard-gelatin capsules, may require testing at low humidity according to the procedure described in this guideline. 

The concentrations of gases in the system depend on the permeability characteristics of permeability, package size and weight of the product that were discussed previously. The time to reach equilibrium can be seen as a limitation of this method to measure the respiration rate. Definition of the steady-state concentration values is another difficulty of the permeable method. 

Accuracy is very sensitive to determination of Free volume Flow-rate Permeability package dimensions, steady-state concentrations... 

An example of historical air-permeable packaging used with gamma sterilization, consisting of a box, two nested, polymeric packages, and an inner foam insert (Osteonics, Allendale, NJ). The UHMWPE component is not shown. 

Historical air-permeable packaging used with gamma sterilization (Wright Medical, Arlington, TN). 

Contemporary gas-permeable packaging for ethylene sterilization of Dunasul highly crosslinked UHMWPE components, used by Centerpulse, Inc. (Austin, TX). 

The UHMWPE material used for Polycentric components was RCH 1000. Gunston sterilized the UHMWPE tibial components he personally manufactured using an autoclave. However, orthopedic companies like Howmedica, which fabricated most of the Polycentric components implanted during the 1970s, sterilized their UHMWPE components with gamma radiation and used air-permeable packaging. 

In the Longevity process, the UHMWPE bars are warmed, placed in a carrier on a conveyor, and are exposed to electron beam radiation, with a total dose of 100 kGy. The UHMWPE does not heat above the melt transition during the crosslinking. After irradiation, the UHMWPE is heated above the melt temperature (>135°C) for stabilization of free radicals. Components are then machined from the Longevity material, enclosed in gas-permeable packaging, and sterilized by gas plasma. 

In the Marathon process, extruded rod bar stock is irradiated with a dose of 50 kGy and then remelted at 150°C (McKellop, Shen, and Salovey 1998) (Figure 15.1). After remelting, the rods are then annealed at 120°C for 24 hours (Greer, King, and Ghan 2003). Acetabular components are machined from the processed bar stock, enclosed in gas-permeable packaging, and then gas plasma sterilized (Figure 15.5). 

The Prolong process is similar to the previously described DURASUL except that an electron beam irradiation dose of 65 kGy is used for Prolong and continuous compression-molded bars are processed as with Longevity. Components are machined from processed Prolong maferial, enclosed in gas-permeable packaging, and sterilized by gas plasma (Figure 15.6). 

Studies of preparations that are packed in water (semi)-permeable packaging material should be performed at constant relative humidity too. Ideal for such studies are climate cabinets in which both the temperature and the humidity can be controlled. Alternatively, saturated aqueous solutions of salts can be used to control the relative humidity in air-tight cabinets [65, 66]. 

Preparations that are packed in water (semi)-permeable packaging material should be checked for evaporation of water by regular weighing. 

Table I summarizes some of the features of anaerobics and acrylics. Both adhesive systems achieve high performance from a room temperature cure. Both systems are initiated by surface reactions, either of the substrate (anaerobics) or the primer surface (acrylics). Anaerobics and acrylics are both oxygen sensitive however, anaerobics are more so, requiring oxygen permeable packaging for stability.

Several potential applications exist for MFCs in the near future, including roles as reduced or controlled permeability packaging materials and as tissue engineering scaffolds. Composite films based on LLDPE matrices have shown excellent improvements in oxygen barrier properties as well as improvements in mechanical properties. 

The driving force for gases and vapors penetrating or diffusing through, for example, permeable packages is the concentration difference between environments inside and... 

The conditions inside and outside packages relate to the gas and vapor pressure forces penetrating or diffusing through permeable packages. As the engineering handbooks report diffiising substance s transmission rate is expressed by mathematical equations commonly called Pick s First and Second Laws of Diffusion very popular in the industry ... 

The use of perforations in otherwise less permeable packages are increasing in the recent years to store highly respiring coimnodities. Plesteiijak et al. observed that a variation in CO and concentrations and consequent accumulation of anaerobic me-... 

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