Monitoring the pharmaceutical pellet coating process?

In the pharmaceutical industry, there are many microgranulated formulations that are coated to achieve a sustained release or a controlled release of the drug or active ingredient over time, a clear and well-known example is Omeprazole. In this article we will talk about these formulations and how to avoid, during the coating process, release and potency analysis using NIR technology. At the end we will explain a concrete case of application.

During the pelletization process of modified release dosage forms, the correct application of the coating (e.g. enteric release coating) will determine the subsequent efficacy of the drug and the mg/API release time of the drug. Because of this, controls are performed throughout this process to ensure the quality and thus the expected pharmacological action.

Currently, this control is performed during coating with samples taken from the coating equipment at different times and analyzed in the laboratory using HPLC or liquid chromatography techniques. This method requires sample preparation prior to analysis, specialized personnel and consumables (materials) for analysis. The main problem with the traditional method of control is that it takes a long time to obtain the results and therefore does not allow rectifying the coating process in case of failures or, if the process has to be stopped, the quality of the semi-product may be altered.

An alternative and very effective tool that allows real-time monitoring of the coating process is the NIR technology, since the spectral signature of each pellet can be related to its coating conditions, dosage and release times without the need to resort to traditional methods.

Application case

An industrial application case with a major pharmaceutical laboratory manufacturer of microgranulated formulations showed that there is a clear correlation between NIR spectra, release times and potency (mg API/g pellet) that is released. In this case, an at-line control with a Visum Palm portable NIR analyzer is currently used.

For the elaboration of the predictive chemometric models it was necessary to take samples throughout the coating process from different batches directly from the coating equipment where both wet and dry samples were measured with the portable NIR analyzer.

Subsequently, release and potency tests were performed on the same samples and preliminary predictive models were developed by correlating the NIR spectra with the values obtained by the traditional tests, resulting in a correlation coefficient (R²) of 0.99. These predictive models showed that, on the one hand, it is not necessary to dry the samples for the prediction – so the control can be performed directly on the wet sample – and on the other hand, that there is a clear relationship between the NIR spectra and the release times of 1h, 4h and 7h. Finally, the wet sample model was further robust and tested with more samples and remotely installed on the customer’s Visum Palm portable NIR analyzer, which as a result of the project was able to perform the coating and release potential control at-line in just seconds and without dependence on laboratory HPLC analysis.

We hope you have found this information on the applicability of NIR spectroscopy for monitoring pellet coating quality useful and invite you to send us any questions you may have on this or other applications to our email news@iris-eng.

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Joel Valdés Bravo
Technical Disclosure
IRIS Technology | Visum