Crystalline microparticles consisting of a phenylalkylamine which is a b₂-adrenergic agonist coated with a C₁₂₋₂₀ fatty acid for use in the preparation of pharmaceutical aerosol formulations in suspension in a liquefied gas propellant or powder formulations. Claim 2: The crystalline microparticles of claim 1, characterized in that the b₂-agonist is selected from a derivative belonging to the general formula (1),Where R1 is ch8322；； Oh o nhcor 183044, but the condition is that R1 is ch8322；； Oh, R2 is always hydrogen, and R1 is nhcor 183044；R2 and r1.83044 can be independent hydrogen or a vinyl (CH = ch -) or etoxi (- ch8322o -)；M is a n integer from 0 to 5, preferably 0 or 5； n is an integer from 0 to 4, preferably 0, 2 or 4； P is an integer from 0 to 2, preferably 0 or 1； a represents oxygen or an alliance； B represents oxygen or an alliance； R3 and r830808 are hydrogen or methyl； or m is 1, N, P is 0, a and B are a combination, R3 is a combination； a. Hydrogen, r830808 can form a methylene bridge (ch8322q) from r83099 - Q is equivalent to 1 or 2, preferably 1； r83099；R8310,R8311th,R8322,R8313,e. If they are the same or different, they are selected independently from the hydrocarbon group of hydrogen, hydroxyl and c832131；C₁₋₄ alkoxy,Halogen atom, so83222nh8322；2-hydroxy-2-phenyl-ethylamine； and salts that are medically acceptable and / or soluble. 13. Claim 7: aerosol pharmaceutical formulations for metered inhaler pressurizer (pMDIs), characterized by the presence of particles from any one of the 1 to 6 requirements, have been suspended for use in LPG propulsion. Claim 11: the process of preparing the particles required in Item 1, which is characterized by the following steps: (a) preparing a c83321 fatty acid solution； (b) in a fluorinated propellant model, b832222 agonino is basically insoluble；Selected from the following categories: perfluorooctane sulfonic acid, 2h, 3h perfluorooctane sulfonic acid (HPFP),Perfluorooctane sulfonic acid and 1H perfluorooctane s
