Method for producing uniform small doses of finely divided substances

Abstract

A process for producing uniform small doses of finely divided substances that consists of forming a well mixed dispersion of a finely divided substance in a liquefied gas and then metering precise quantities of the mixture onto the surface of a containment vessel. A major application involves the packaging of fine pharmaceutical powders into small unit doses for inhalation therapy. Liquid nitrogen is the preferred liquefied gas. A liquefied noble gas may be employed as a dispersing medium for sensitive or highly reactive substances. Powder particle size reduction may be carried out in the liquid nitrogen medium with little or no damage to sensitive pharmacological materials. The atmosphere of the seated containment vessel is easily pressurized with nitrogen. The containment vessel may be seated prior to the total evaporation of the liquefied gas dispersing medium. The containment vessel is thus pressurized to relatively high pressures to facilitate the subsequent aerosolization of the pharmaceutical in an inhaler during inhalation therapy.