Use of soluble fluorosurfactants for the preparation of metered-dose aerosol formulations

A suspension aerosol formulation, comprising:

• a propellant comprising a hydrofluorocarbon selected from the group consisting of 1,1,1,2-tetrafluoroethane and 1,1,1,2,3,3,3-heptafluoropropane, and a mixture thereof;
• a therapeutically effective amount of a powdered medicament;
• and between about 0.001 and 0.6 percent by weight based on the total weight of said formulation of a surface-active dispersing agent of the formula ##STR3## wherein R.sub.f is selected from the group consisting of perfluorinated straight chain, branched chain, or cyclic alkyl or combinations thereof containing three to about ten carbon atoms, wherein cyclic alkyl optionally contains one or more catenary oxygen or nitrogen atoms;
• each X is independently selected from the group consisting of fluoro and straight chain or branched chain perfluoroalkyl of one to about four carbon atoms,
• n and m are independently integers from zero to three with the proviso that the sum of n and m is less than or equal to four;
• and
• Z is selected from the group consisting of hydrogen and straight or branched chain alkyl containing one to about four carbon atoms,
• the formulation exhibiting substantially no crystallization of said medicament over a prolonged period, being substantially readily redispersible, and upon redispersion non flocculating so quickly as to prevent reproducible dosing of the medicament.