The invention comprises a medicinal aerosol composition comprising a propellant, an excipient comprising an acid or amine end-group and at least one and no more than two amide and/or ester functional groups, and a drug. The invention also comprises particulate medicinal compositions comprising particles with a mean mass aerodynamic diameter of less than about 10 microns that incorporate an excipient containing an acid or amine end-group and at least one and no more than two amide and/or ester functional groups.