Explosive Hazard Identification in Pharmaceutical Process Development: A Novel Screening Method and Workflow for Shipping Potentially Explosive Materials

When a material is identified as potentially capable of explosive propagation by the Yoshida correlation, process safety scientists have few options for semiquantitatively assessing the hazards associated with the use of that material. Oxygen balance calculations, the Rule of 6, and the United Nations (U.N.) explosive functional group list are commonly employed qualitative/semiquantitative methods to assess explosivity without requiring additional experimental data. In contrast, a full United Nations Transportation of Dangerous Goods testing regimen requires, at a minimum, 2 kg of material for Test Series 1 alone, an excessive amount that is rarely available in early pharmaceutical development. A new assessment, called the O.R.E.O.S. method, has been developed that combines the three traditional methods for screening of explosive properties (Oxygen balance calculations, the Rule of 6, and the Explosive functional group list) with the Onset of decomposition determined by differential scanning calorimetry and the proposed Scale. This new assessment has been applied to known energetic materials that are flagged as potentially capable of explosive propagation by the Yoshida correlation and has been shown to be effective at classifying materials in a scale-dependent manner. The tool is customizable to fit any organization’s internal guidance on handling energetic materials. This assessment should find wide utility in both pharmaceutical development groups and contract research organizations as a means to classify compounds that may require further testing before scale-up or to steer project teams to discover safer alternatives. A brief description of the challenges associated with transporting materials for U.N. Series Testing is also presented with the aim of demystifying the process for obtaining such valuable data.