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Leibniz Lecture: The Stability and Bioavailability of Drugs

4/5/2017, 6:30 PM to 8:30 PM | German House New York

Leibniz Lecture: The Stability and Bioavailability of Drugs

• German Research Foundation (DFG)
• UARuhr

On April 5th, 2017, the German Center for Research and Innovation (GCRI) New York, the University Alliance Ruhr, and the German Research Foundation (DFG), hosted a Leibniz Lecture on “The Stability and Bioavailability of Drugs.” The lecture, which was given by Prof. Dr. Gabriele Sadowski, Professor for Thermodynamics at the TU Dortmund University and Leibniz Prize winner in 2011, addressed the thermodynamic stability of drug formulations and the factors affecting drug bioavailability in the body after administration.

The public event was opened by Dr. Joann Halpern, director of the GCRI New York, who described the important role of the GCRI as a platform and a forum that fosters collaboration in science and technology between North America and Germany. Afterwards, Dr. Annette Doll-Sellen, director of the New York office of the German Research Foundation (DFG), spoke about the significance of the prestigious Leibniz Prize, which is awarded annually by the DFG. Peter Rosenbaum, executive director of the University Alliance Ruhr extended a warm welcome to the audience and introduced Prof. Dr. Sadowski and her research, which is focuses on thermodynamic properties of complex systems with a particular emphasis on those containing biological and pharmaceutical molecules.

Prof. Dr. Sadowski opened her lecture by explaining that 80% of high-impact pharmaceuticals with the potential to treat severe diseases never reach the market. The reason for this is the low solubility of the active pharmaceutical ingredients (APIs) that prevent the body from absorbing the medication. At present, most APIs are hydrophonbic and thus have a very low bioavailability. Prof. Sadowski stressed the importance of enhanced bioavailability of drugs for the pharmaceutical industry.

Several approaches exist to increase the bioavailability of drugs. Most of them aim at formulating the drug in a less-stable but more soluble form which is intended to be stabilized with the help of excipients, e.g. polymers. Specifically, crystalline APIs are transformed into an amorphous form. The disadvantage of this approach is the amorphous API that is embedded in a polymer matrix still tends to recrystallize which is thermodynamically less stable than the crystalline API, hence thermodynamically unfavorable. This means that the amorphous API needs to be stabilized by embedding (dissolving) it in a suitable polymer matrix.

In order to avoid API recrystallization, Prof. Dr. Sadowski stated that tablets need to be thermodynamically stable. In this stable state, the amorphous solid dispersion (ASD) will never change as long as the environment does not change. However, it will only remain stable for a finite amount of time. The tablet’s formulation is also influenced by the excipients, temperature, and relative humidity. When the humidity rises it is harder to keep the tablet in a stable state, since it absorbs the water from the air. A tablet that is open for several hours absorbs a lot of water and starts to crystalize. This is the reason for blister packaging of pharmaceuticals. “You should not take a tablet out of the blister long before you decide to take it. It is best to take it out of the blister and consume it immediately”, Prof. Dr. Sadowski advised the audience.

She continued to explain how thermodynamic modelling can result in reliable correlations and even predictions of conditions that lead to high stability. A thermodynamic model makes it possible to calculate the water absorption, the API solubility in different environments as well as under what conditions amorphous demixing can be expected. Thanks to the model, different types of formulations can be tested. Prof. Dr. Sadowski is optimistic that the scientific model reduces the experimental effort to develop the optimal drug formulations as well as their processing.

During the engaging Q&A that followed, the Prof. Sadowski answered questions from the audience that ranged from the applicability of the model for drug formulation development in the biopharma business, methods for the daily storage of tablets, to future research and technology in this area.

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  • Featured Speakers

    • Prof. Dr. Gabriele Sadowski

      Gottfried Wilhelm Leibniz Award Winner 2011; Professor for Thermodynamics, TU Dortmund University