ELECTROSTATIC CHARGE AN A PLASTIC SPACER DEVICE INFLUENCES THE DELIVERY OF SALBUTAMOL

The aim of this study was to determine whether electrostatic charge on a plastic spacer decreases the delivery of salbutamol from a pressuri zed metered-dose inhaler (pMDI) and, if so, to find an optimal and pra ctical treatment to remove the charge. Ten single actuations from a sa lbutamol pMDI were drawn through different Volumatic(R) spacers at a c onstant flow of 60 L . min(-1). The efficacies of different methods of removing charge were tested, including detergent coating of the space rs, A multistage liquid impinger was used to determine the particle si ze distribution of the output of the pMDI through the Volumatic(R) spa cers, The electrostatic Roberts Road charge on the inner surface of th e spacers was measured both quantitatively with Western Australia an e lectrometer, and qualitatively by the attraction of a thin strip of ce llulose membrane to the wall of the spacer, Each experiment was repeat ed four times. Ionic detergent coating of the spacers removed the char ge for at least 24 h. This resulted in an increase of 55-70% in small particle (<6.8 mu m) delivery compared to delivery from new spacers wi th high charge. We have demonstrated that electrostatic charge plays a major role in the delivery of salbutamol through plastic spacers, Ade quate treatment with ionic detergent removes the charge and improves d rug delivery.