Drug manufacturing

Drug manufacturing is the process of industrial-scale synthesis of pharmaceutical drugs by pharmaceutical companies. The process of drug manufacturing can be broken down into a series of unit operations, such as milling, granulation, coating, tablet pressing, and others.

Before a drug can be manufactured at any scale, much work goes into the actual formulation of the drug. Formulation development scientists must evaluate a compound for uniformity, stability and many other factors. After the evaluation phase, a solution must be developed to deliver the drug in its required form such as solid, semi-solid, immediate or controlled release, tablet, capsule, injection, and many other variations.

In the pharmaceutical industry, a wide range of excipients may be blended together to create the final blend used to manufacture the solid dosage form. The range of materials that may be blended (excipients, API), presents a number of variables which must be addressed to achieve products of acceptable blend uniformity. These variables may include the particle size distribution (including aggregates or lumps of material), particle shape (spheres, rods, cubes, plates, and irregular), presence of moisture (or other volatile compounds), and particle surface properties (roughness, cohesivity).

During the drug manufacturing process, milling is often required in order to reduce the average particle size in a drug powder. There are a number of reasons for this, including increasing homogeneity and dosage uniformity, increasing bioavailability, and increasing the solubility of the drug compound.

Granulation can be thought of as the opposite of milling; it is the process by which small particles are bound together to form larger particles, called granules. Granulation is used for several reasons. Granulation prevents the "demixing" of components in the mixture, by creating a granule which contains all of the components in their required proportions, improves flow characteristics of powders (because small particles do not flow well), and improves compaction properties for tablet formation.

Hot melt extrusion is utilized in pharmaceutical solid oral dose processing to enable delivery of drugs with poor solubility and bioavailability. Hot melt extrusion has been shown to molecularly disperse poorly soluble drugs in a polymer carrier increasing dissolution rates and bioavailability. The process involves the application of heat, pressure and agitation to mix materials together and ‘extrude’ them through a die. Twin-screw high shear extruders blend materials and simultaneously break up particles. The resulting particles can be blended and compressed into tablets or filled into capsules.

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