BSC classes

Drug absorption enhancers have been intensively studied over the past three decades [190— 192] in order to increase the oral availability of poorly absorbed drugs (BSC classes II-IV) [193,194]. Much attention has been paid to the synthesis and evaluation of new absorption enhancer molecules. Excluding the preparation of polymer drug conjugates less awareness was focused on the delivery rate of the molecules tested that is, the concomitant input of the poorly soluble drug together with its enhancer, so that maximal area of the small intestine would be exploited for absorption. The differences between the dimensions of the GI tract in... 

ASTM A 320 Grade BSC Class 2 See Note 8 AISI 347 strain hardened... 

BSC class II cabinets protect personnel, the environment, products, and specimens. These cabinets contain an open front and an inward airflow of 75-100 fpm to protect the operator. The laminar air that comes in contact with the product is first HEPA filtered to protect the product from contamination. The exhaust air then goes through a second HEPA filter to protect the environment. Use class II cabinets with products requiring biosafety levels 1, 2, or 3 containment. 

Biological safety cabinets (BSCs) used in the United States are divided into three classes 1,11, and III. Class II cabinets are further divided into four types A, Bl, B2, and B3." In other countries, other categorization schemes are sometimes used, but usually follow the same general operating conditions. This division is quite unlike the rest of the local ventilation chapter, but since these descriptions are used whenever BSCs are used, it is practical to describe them here. 

Class I BSCs are, from the functional view, similar to a fume cupboard (Section 10.2.3). Class II cabinets are used for product and worker protection. Class III cabinets are used for work with very dangerous microbiological or radioactive agents and provide maximum protection to the environment and the worker. The class and type of BSC used is dependent on the demands for worker and product protection. 

Class I The Class I BSC provides personnel and environmental protection, but no product protection. It is similar in air movement to a chemical fume cupboard, but has a HEPA filter (see Chapter 9) in the exhaust system to protect the environment (Fig. 10.94). In the Class 1 BSC, unfiltered room air is drawn across the work surface. Personnel protection is provided by this inward air velocity as long as a minimum velocity of 0.37 m s" is maintained through the front opening (see the discussion on fume cupboards in Section 10.2.3.3). In many cases Class I BSCs are used specifically to enclose equipment. 

The Class 1 BSC is hard-ducted to the building exhaust system, and the building exhaust fan provides the negative pressure necessary to draw room... 

FIGURE 10.94 The Class I BSC ( Front opening. 6 Sash. C Exhaust HEPA filter. 0 Exhaust pie num). 

Some Class I BSCs are equipped with an integral exhaust blower the cab inet blower must be tiiterloclced with the building exhaust fan. In the event that the building exhaust fan fails, the cabinet exhaust blower must also turn off so that the exhaust ducts are not pressurized. If the ducts are pressurized and the HEPA filter develops a leak, contaminated air could be discharged into other parts of the building or the environment. 

Class HA in a Class IIA BSC, an internal blower (Fig. 10.9,St draws sui-ficient room air into the front grill to maintain a minimum calculated measured average velocity of at least 0.37 m s at the opening of the cabinet. The supply air flows through a HEPA filter and provides particulate-free air to the work surface. Laminar airflow reduces turbulence m the work zone and niim-mizes the potential for cross-contamination. 

FIGURE 10.95 The Class IIA BSC (A From opening. C Sash. C Exhaust HEPA filter. D Rear plenum E Supply HEPA fitter. F Blovyer). 

An unducted Class IIA BSC should not be used for work involving hazardous or toxic gases and vapors. The buildup ot chemical vapors in the cabinet by recirculated air) and in the laboratory (from exhaust air) could create health and safety hazards. 

FIGURE 10.96 The Class II BI BSC. classic design (A Front opening. 8 Sash. C Exhaust HEPA filter. 

Class UB2 The Class 11B2 BSC is a total-exhaust cabinet no air is recirculated w ithin it (Fig. 10.97). This cabinet provides simultaneous primary biological and chemical containment. The supply blower draws in room air or outside air at the top of the cabinet, passes it through a HEP,IV filter, and down into the work area of the cabinet. The building or cabinet exhaust system draws air through both the rear and front grills, capturing the supply air plus the additional amount of room air needed to produce a... 

Class 1IB3 A Class IIB3 BSC (Fig. 10.98) is a ducted Type A cabinet having a minimum inward air velocity of 0.5 m s E All positive-pre.ssure contaminated plenums within the cabinet are surrounded by a negative air pressure plenum. Thus, leakage in a contaminated plenum will be into the cabinet and not into the environment. 

FIGURE 10.97 The Class II B2 BSC (A front opening, fl Sash. C Exhaust HEPA filter. D Suf ly HEPA fitter . Negative pressure exhaust plenum. Fz Supply blower. G Filter screen). Note Connection to building exhaust system is required. The carbon filter m the building exhaust Is not shown. 

A Class I BSC fitted with an added panel covering the opening and fitted with arm-length gloves, becomes, in many ways, similar to a glove box de-... 

The CDC-NIH document describes, in detail, the different uses of the different classes and types of BSCs and the type of protection (personnel, product, and environmental) each type provides. The document also provides a detailed comparison of filtration (air cleaning), airflow pattern (into the cabinet from the room or from the supply duct), and necessary performance tests (leak, velocity profile, differential pressure, etc.) for each type of BSC (see also Simons ). 

Biopharmaceutics Classification System Redefining BSC Solubility Class Boundary... 

The Brunswick Subduction Complex (BSC) is best know as the host sequence to world class, syngenetic volcanogenic massive sulfide deposits of the Bathurst Mining Camp (BMC) hosting deposits such as the giant Brunswick No. 12 VMS deposit (>300 Mt of massive sulfides). Less well known are the syntectonic, precious-metal breccia and (or) vein deposits/occurrences in the BSC. The shear zone-hosted Middle River gold deposit (MRG) is the most significant of these and has returned assays of up to 7.44 g/t Au over 6.5 m (DDH MR-05-06). 

I was admitted to Imperial College in October 1938 when I was 20 years old. Because of the good marks I had obtained in the entrance examinations I was allowed to proceed directly into the second year. I completed the BSc with First Class Honors in 1940. Because of what turned out to be a minor problem with my heart, I had earlier been called to the Army and rejected. In any case, I was in a reserved profession and expected to work on a subject of national importance. 

Class I BSC. The Class I BSC is an open containment unit suitable for work involving agents of low to moderate risk to the user and environment, where there is a need for containment but none for product protection or isolation. The Class I BSC provides protection to personnel using the cabinet by means of constant, controlled airflow into the work area and away from the operator, preventing the escape of aerosols through the front opening. It is of limited use in manufacturing and has no reported use in the current practice of pharmacy. 

Class II BSC. The Class II BSC (Fig. 9) provides product, personnel, and environmental protection, and is the most common BSC employed in pharmaceutical manufacturing and pharmacy-compounding operations. The Class II BSC has several subclassifications, based upon cabinet ventilation design (Table 1). The Class II BSC (Fig. 8), the most widely used by hospital and home-care pharmacies, features a front access opening with carefully maintained inward airflow for replacement of air exhausted from the cabinet, a HEPA-filtered vertical laminar flow airstream within the entire work area, and HEPA-filtered exhaust air. The vertical laminar flow airstream and front access opening are common to all Class II cabinets, although LAF velocities and patterns, HEPA filter sizes and position, ventilation rates, and cabinet exhaust methods vary considerably in different designs (Fig. 7). 

The Class III BSC is a gas-tight enclosure, utilizing total air displacement ventilation that protects personnel from exposure to the products contained within the enclosure, the product from contaminants found in the ambient environment, and the environment from release of potentially hazardous substances. The Class... 

In addition to cleaning all accessible work zone surfaces, the Class II BSC worksurface tray should be lifted up and back, and the area under the tray should be thoroughly cleaned with the same frequency as the other user-accessible worksurfaces this is of particular importance in preventing the buildup of potentially harmful product residues. All materials used in cleaning and sanitizing should be treated as toxic waste, and disposed of in accordance with state and local... 

Fig. 8 Airflow patterns of the Class 11(a) laminar flow BSC. (Courtesy of the Baker Company, Sanford, Maine.)...

In industry, the BSC is used to conduct small batch sterile-fill operations, manipulation (weighing and pouring), isolation of hazardous materials, and in QA/QC testing applications. All classes of BSC are encountered in pharmaceutical manufacturing operations for a wide variety of processing applications. 

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