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Loop systems distributing purified water also exist in most facilities, with their design being somewhat similar to WFI systems. The more relaxed microbiological specifications relating to purified water renders the design and operation of such systems less complex. Purified water is generally circulated at ambient temperatures, via stainless steel or sometimes plastic-based tubing.
Samples of WFI and purified water are usually collected daily by quality control personnel, and tested for conformance to specification. Failure to meet specification results in the system being emptied and fully sanitized, before generation of fresh water.
Adequate documentation forms an essential part of good manufacturing practice. For this reason, every aspect of pharmaceutical manufacture is characterized by the existence of extensive associated documentation. This is essential in order to:
help prevent errors/misunderstandings associated with verbal communication;
facilitate the tracing of the manufacturing history of any batch of product;
ensure reproducibility in all aspects of pharmaceutical manufacture.
Most documents associated with pharmaceutical manufacturing fall into one of four categories:
standard operating procedures (SOPs);
manufacturing formulae, processing and packaging instructions;
Great care is taken when initially preparing such documents to ensure they are written/ worded in a clear and unambiguous fashion. They are usually written by supervisory personnel,
and inspected by senior technical personnel (often the production or QC manager or both), before their final approval for general use. Such documents are reviewed regularly, and updated as required.
SOPs are documents which detail how staff should undertake particular procedures or processes. These procedures/processes are usually of a general nature, often being independent of any one pharmaceutical product. Many SOPs fall into one of several general categories, including:
SOPs detailing step-by-step operational procedures for specific items of equipment (e.g. autoclaves, homogenizers, freeze-dryers, pH meters, product labelling machines, etc.);
SOPs detailing maintenance/validation procedures for specific items of equipment or facility areas, e.g. SOPs detailing CDS of clean rooms;
SOPs relating directly to personnel (e.g. step-by-step procedures undertaken when gowning-up before entering a clean room);
SOPs relating to testing/analysis (e.g. procedures detailing how to properly sample raw materials/finished product for QC analysis, SOPs relating to the routine sampling and testing of WFI from the ring main system, etc.).
Specifications are normally written by QC personnel. They detail the exact qualitative and quantitative requirements to which individual raw materials or product must conform. For example, specifications for chemical raw materials will set strict criteria relating to the percentage active ingredients present, permitted levels of named contaminants, etc. Specifications for packing materials will, for example, lay down exact dimensions of product packaging cartons; specifications for product labels will detail label dimensions and exact details of label text, etc. Specifications for all raw materials are sent to raw material suppliers and, upon their delivery, QC personnel will ensure that these raw materials meet their specifications before being released to production (the raw materials are held in quarantine prior to their approval). Final product specifications will also be prepared. As most products are manufactured to conform with pharmacopoeial requirements, many of the specifications set for raw materials/finished product are simply transcribed from the appropriate pharmacopoeia.
Manufacturing formulae, processing and packaging instructions
Manufacturing formulae should clearly indicate the product name, potency or strength, and exact batch size. It lists each of the starting raw materials required, and the quantity in which each is required. The processing instructions should contain step-by-step manufacturing instructions. The detail given should be sufficient to allow a technically competent person, unfamiliar with the process, to successfully undertake the manufacturing procedure.
The processing instructions should also indicate the principal items of equipment utilized during manufacture, and the precise location in which each step should be undertaken (e.g. in a specific clean room, etc.). It will also list any specific precautions which must be observed during manufacture (e.g. precautions to protect the product from, perhaps, excessive heating, or to protect the operator from any potentially dangerous product constituent). Each product will also have its own labelling and packing instructions, indicating:
the label to be used, and its exact text;
THE DRUG MANUFACTURING PROCESS 111