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There is a need to provide a safe and accurate way of preparing many drugs for administration. In terms of delivery, it is more practical for parenterals to be preformulated as they are administered intravenously. This means that the process of preparing parenterals is similar to that of preparing injections as just as injection volumes increase, so does the number of formulations required. In general, there are two main types of processes used in preformulation: batch and continuous. In batch processing, the process is initiated with the formulation of a mixture that is then subjected to each subsequent step in sequence. In contrast, in continuous processing, each subsequent step is performed simultaneously in a process where base work and feed streams are fed continuously causing a continuous mixing operation. The scope of preformulation ranges from basic drug substance formulation to dry powder blending or depyrogenation of final products. However, most drugs have been successfully prepared by means of simple solutions up to advanced multistep processes. In general, preformulation involves synthesis and purification of individual chemicals which are then assembled into a drug product for dosage form manufacture. A process will be considered feasible by preformulation if it can be carried out in a manner deemed acceptable, given the available equipment and facilities. This may require some adjustments such as addition steps, multiple mixing processes or concentration of intermediates to make it possible. Furthermore, the process should take into account economical factors such as reduction in raw materials and facility size reduction.There are many types of preformulation processes used in the preparation of parenterals. They include: simple solution methods, precipitation methods, multi-step methods and complex methods that involve vapor-phase reactions or solid state reactions. The preformulation process may include a simple determination of chemical purity which is practiced when only chemical purity is needed for further processing. Simple methods involve the addition of ingredients to water or other solvents, followed by dilution. Dilution may be done through pasteurization. The mixture is then pasteurized and cooled before concentration is performed after which the mixture is again diluted. This process may include simple drying or evaporation processes depending on the end product. Precipitation methods involve mixing of ingredients in melted form that are then allowed to solidify resulting in precipitation of one ingredient from solution by another ingredient which precipitates out due to electrostatic charge interaction. The result is usually a specific crystal form of one or more ingredients which act as an anchor for other substances in solution to form complex mixtures known as multistep processes. The physical state of the product may be essential to the final stability of the drug. Therefore, many different methods are used in production to help protect or modify physical properties. These include precipitation / dissolution methods which involve mixing, melting and cooling steps that form safe and suitable solids for parenteral use. The complexity involved with multistep processes will depend on the chemical complexity of the final drug formulation as well as on process limitations such as time parameters, space constraints and equipment availability. In general, multistep processes are costly as they involve more equipment and give rise to significant capital expenditure which is often not recovered through economic factor alone. cfa1e77820
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