How XRD impacts formulation of pharmaceutical drugs

Since XRD testing is non-destructive it is possible to explore properties of pharmaceutical samples to analyse whole tablets and capsules without the need to destroy or dissolve them. This type of analysis helps to determine the final dosage forms as well as the active pharmaceutical ingredient (API) in the finished product. Most of the materials in the formulation are excipients like lubricants, pigments, buffering agents, fillers which make up the bulk of the drug. Among all these excipients the correct amount of the API must be mixed. Mixing formulation would be complex but it has to a large extent become easy because X-ray diffraction analysis helps to identify all the ingredients and makes it possible to ensure uniform distribution in the final product.


During drug formulations the excipients can sometimes overlap the API in the drug product so this will require reducing the excipient content which is possible with XRD detection. Also pharmaceutical drugs most often use more than one excipient according to their functions in drug delivery. XRD is used to first find out the excipients before analysing the API especially if it is in small concentrations. XRD is used to check the homogeneity of all the components used in the drug as incomplete mixing can lead to an error in the formulation. In the same way,to avoid errors in formulation X-ray diffraction is used by pharmaceutical manufacturers to detect even very small crystalline impurities and the level of amorphous content.

Through X-ray diffraction it is possible to study the different phases of the surfaces of pharmaceutical drugs. Studying phases works to determine if the drugs are undergoing any changes due to humidity and temperature, as these changes impact shelf life. Some XRD instrumentations also have temperature and humidity chambers that can examine the shelf life of tablets under controlled conditions. Another area where XRD proves useful is in detecting changes in morphology during production as that ensures that the finished product is being processed consistently.

One of the major issues with drug formulation is poor water solubility. Among other steps taken to improve solubility like reducing particle size, many a time the drug is prepared in an amorphous form. However, amorphous forms of the drug can crystallize, especially when stored in high humidity. Also if the amorphous material precipitates it could give rise to poor bioavailability and drug dissolution so X-ray diffraction is used during drug formulation to check if the amorphous form is suited for formulation or does it have a tendency to crystallise or become weak and ineffective. XRD can therefore help to determine the best form of the drug which leads to the correct end result.

X-ray diffraction when used on vitamins will identify each component and so only the correct polymorph is present. Wrong or inert polymorph has no potency and the formulation will become useless. XRD makes it possible to make a quantitative determination of each component and also measure its intensity so the potency of the formulation has the desired effect.


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