EPR in Pharma

EPR in Pharma

Electron Paramagnetic Resonance (EPR) spectroscopy is the only technique for the direct and non-invasive detection of unpaired electrons in paramagnetic species (free radicals and transition metals), which has many applications in the pharmaceutical industry. In this collection of application flyers, you can learn how benchtop EPR can be used to solve a variety of questions.

I. Detecting and Evaluating Degradation

Degradation processes quite often involve free radicals and transition metals that are responsible for most of the damage that occurs in drug products. By analyzing an EPR signal, one can identify, quantify and monitor time behavior of the free radicals involved in product degradation.

II. Optimizing Stability and Shelf-Life

Forced degradation (stress testing) is routinely used in pharmaceutical development to predict the stability of drug products that affects purity, potency, and safety. EPR can successfully detect and monitor short-lived free radicals produced during stress testing via chemical, thermal, or photochemical reactions. EPR can also determine radical scavenging effectiveness and efficiency of antioxidants.

III. Reaction Monitoring

Chemistries involving radicals, transition metals and other unpaired electron species are integral components of maximizing product yield and minimizing the environmental footprint of synthetic reactions. Reaction monitoring is critical for process understanding, optimization and scaling up, leading to cost savings and ensuring the quality of the final product. The quantitative and non-intrusive nature of EPR makes the technique extremely powerful for the identification and characterization of radical and transition metal reaction intermediates, providing insights into the mechanisms and kinetics of chemical reactions.

IV. Sterilization Processes

Sterilization of pharmaceuticals often generates free radicals that are responsible for degradation and drug potency decrease, toxicity of the sterilized materials, etc. EPR can determine stability of drug products after sterilization, characterize the free radicals and identify their source.

V. Paramagnetic Impurity Profiling

Identification, quantification, and control of impurities in APIs and formulation products are critical in drug development. EPR can detect and identify traces of transition metals and monitor degradation processes that involve free radicals, transition metal catalysts, and other impurities.

Bruker Technical Paper Series

EPR (Electron Paramagnetic Resonance) is a spectroscopic technique that detects species that have unpaired electrons. It is also often called ESR (Electron Spin Resonance).


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