Pharmaceutical Industry | Chemical Analytics | Measurement of Powdery Pharmaceutical Drugs

Drugs are indispensable to combat diseases. The effectiveness of a drug depends, amongst other factors, on the bioavailability of the active ingredient contained in the drug. It indicates the speed and extent to which the active ingredient enters the bloodstream. If the drug is not released in sufficient quantity or too quickly in the body, it remains ineffective (see figure 1).

One of the most important challenges is the low aqueous solubility of the active ingredients. This hinders the bioavailability of orally administered drugs and requires special processing techniques. These and other parameters must therefore be continuously monitored to ensure the optimum efficacy of the end product.

For optimal effectiveness of the drug critical quality attributes such as particle size distribution, residual solvent content, bulk density and morphology must be monitored and controlled. A decisive and quality-determining process step in which the above-mentioned parameters can be influenced is the drying of an active ingredient dissolved in a solvent and mixed with excipient. A preferred method in this context is the process of spray drying. It is used to produce inhalable powder and obtain an amorphous solid dispersion.

During spray drying, various parameters must be closely monitored

During the process of spray drying, the complex interactions between the liquid to be dried and the heated gas can influence both the morphology and the particle size. It is important to keep these parameters within specific values since they can influence the release profile of the drug.  

Spray drying is used, for example in the manufacture of pharmaceutical intermediates. A great advantage of spray drying is that the contact between the spray material and the hot drying gas is very short, so that even thermally sensitive substances can be dried. Drying a single drop takes less than 1 second.

One parameter that must be continuously and precisely monitored during this process step is the water content in the powder. It is important that the residual moisture of the resulting powder complies to strict specifications. Deviations can affect the downstream processes, powder flowability and ultimately the performance of the drug.Typical effects when the residual moisture is too high are, for example, clumping and ultimately decrease on yield.

A more detailed description on how this application was realized using online measurement technology can be found in our detailed application report, which you can download from the info column at the top of the page.