Stock preparation importance

Activation of PE residues with these crosslinkers can proceed by one of two routes the purified PE phospholipid may be modified in organic solvent prior to incorporation into a liposome, or an intact liposome containing PE may be activated while suspended in aqueous solution. Most often, the PE derivative is prepared before the liposome is constructed. In this way, a stable, stock preparation of modified PE may be made and used in a number of different liposomal recipes to determine the best formulation for the intended application. However, it may be desirable to modify PE after formation of the liposomal structures to ensure that only the outer half of the lipid bilayer is altered. This may be particularly important if substances to be entrapped within the liposome are sensitive or react with the PE derivatives. 

In separate sections the importance of choosing and defining relevant quality parameters to guarantee the required quality of the medicine is discussed. It is explicitly mentioned that stock preparations are generally tested more extensively than extemporaneous preparations. It is also mentioned that if it is not practical to perform tests on pharmacy preparations, for example because the batch is too small or because of the delivery time, other suitable methods may be used to guarantee that the required quality level is met. With this, the process validation has obtained an official position next to the end control of products. It should be stressed, however, that when tested at any point during the product shelf life the product must meet the specification in the monograph. 

Generally this will be about the choice of another chemical form, for example theophylline instead of aminophylline or carbasalate calcium instead of acetylsalicylic acid. It is important to pursue a consistent policy on this, for both the stock preparation as well as the extemporaneous preparation and the policy should be clear and consistent. The prescriber should be consulted in order to explain changes to the prescription and in many Countries should be asked consent. 

When a BPI is drafted, it is important to present a clear, compact collection of information. The text must be unambiguous, legible and factually correct. Depending on the scale of production, a BPI may consist of only one page for a standardised extemporaneous preparation or may contain multiple pages for stock preparations. The right combination of preparation process, in-process controls and... 

A good working discipline is essential to prevent cross contamination. This requires careful planning, but a system for identification as well. In stock preparations the identity of the product in operation must be fixed to premises, equipment and vessels. For this purpose labels can be used, or a form that is part of the preparation record. Logbooks can also play an important role in the securing of the history of use of rooms and equipment (see Sect. 33.7). If a room or equipment has been cleaned according to the applicable procedure, the status indicatimi clean has to be applied. 

In some situations, for example with very short-lived radiopharmaceuticals, conditional release before all QC tests are performed is necessary. As a consequence, process validation is important An immediate recall procedure must take place, when product quality is found to be insufficient Stock preparations usually undergo an extensive analytical control (see Sect. 34.9.2) and remain in quarantine until the QC is fuUy completed (see Sect. 34.9). The release is based on the assessment of the document control in combination with the analytical quality controls. During release, final reconciliation takes place. For certain preparations (e.g. aseptic preparations) also the results of monitoring of production conditions are included. 

The duty of care for the pharmacist impUes that he considers the consequences for his patient(s) of not preparing a preparation that is required by the physician and the patient. He may consider the availability of a specific medicine to be more important than the degree of quality assured by a Ucensed preparation. The pharmacist should balance the safety of the product (therapeutic qualities including toxicity and adverse events, design quality and product quality) and the unavailability of the medicine. This balancing (see Sect. 2.2) refers to an individual patient in case of an individual preparation or to a defined indication or patient groups in case of a stock preparation. 

The expiry date of pharmacy preparations depends on the date of preparation, the conditions under which the preparation is made, the type of container and the storage conditions. It should always be part of the label of stock preparations. In practice, it will not always be necessary for the patient to know this expiry date, as long as the beyond-use date lies before the expiry date, and the container is opened shortly after dispensing. Most important for the patient is that the label is clear and unambiguous on the maximum period of storage. 

Refining is very important in the stock preparation process for virgin chemical pulp. For mechanical and recycled fibers refining has lower importance. The refining of recycled fibers usually aims for strength increase and shive elimination or reduction. 

The main field of automation in a fiber stock preparation system Hes in the control of those operational parameters which are important for every stage in the process e.g. consistency, flow, pressure, level, power consumption and tempera-... 

The agitation of pulp stock for homogenization and blending is the most common mixing operation in pulp and paper manufacture. The blend chest (a well-mixed stirred vessel) illustrates the importance of macroscale mixing in pulp and paper processes. It is the heart of the stock preparation system and is used to mix two or more pulp streams, often with wet-end chemicals, dyes, fillers or additives, as well as providing a uniform feed of stock to the paper machine. Mixing chests... 

Historically, the use of acetylene as raw material for chemical synthesis has depended strongly upon the avadabihty of alternative raw materials. The United States, which until recendy appeared to have limitless stocks of hydrocarbon feeds, has never depended upon acetylene to the same extent as Germany, which had more limited access to hydrocarbons (1). During Wodd War 1 the first manufacture of a synthetic mbber was undertaken ia Germany to replace imported natural mbber, which was no longer accessible. Acetylene derived from calcium carbide was used for preparation of... 

STEP 1 PREPARATION OF STOCK SOLUTIONS. The aqucous Cd solution is prepared as for CdS. As for CdS, the nature of the anion does not appear to be very important—the sulphate is commonly used. 

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