Measurement of electrostatic charge decay in pharmaceutical powders and polymer materials used in dry powder inhaler devices.

The electrostatic charge generated on drug/excipient particles during the formulation, manufacture, and use of pharmaceutical dry powder inhaler (DPI) devices may significantly affect the performance of such devices. An experimental investigation has been undertaken of charge accumulation and decay on compacts of selected powders (lactose and salbutamol sulfate) and a device material (polyvinyl chloride, PVC) used during the formulation, manufacture, and use of DPIs. Significant differences in charge acquisition and decay for the three materials have been demonstrated after charging using a corona electrode. PVC acquired the highest charge, which decayed rapidly in 30 min toward the value prior to exposure to corona. Lactose and salbutamol acquired similar charge values, which decayed to zero after 30 min for lactose, whereas salbutamol retained a significant charge after 120 min. The significant differences in charging propensity among drug, excipient, and device materials may have relevance in DPI formulation, manufacture, and use.