title: Percutaneous absorption of alkanoic acids II: Application of regular solution theory.
abstract: The permeability coefficient, Kp, of pure unbranched alkanoic acids (C2-C7) applied to isolated porcine skin, reached a maximum in the solubility parameter (delta 2) range of 9.7-10 cal1 /2/cm3/2. When these and other penetrants were delivered from a solvent vehicle, the following linear relationships could be demonstrated: (a) between log Kp and the molar attraction constant of the penetrant [delta 2v2 or (-Ev)1/2] for six unbranched and six branched acids delivered from 1 M solution in n-heptane; (b) between Kp and the partial molal volume difference in n-heptane (-v2-v02) for the unbranched acids; and (c) between Kp and (-v2-v02) for propionic acid delivered from 1 M solutions in nine solvents having delta 1 values in the range 7.4-12.7 cal1 /2/cm3/2. Drug penetrability in a given series could be assessed from knowledge of the excess free energy of the penetrant in the delivery system used.
mesh_terms: D000818:Animals; D002264:Carboxylic Acids / Q000378:metabolism*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D066298:In Vitro Techniques; D007536:Isomerism; D007700:Kinetics; D008297:Male; D008954:Models, Biological; D014677:Pharmaceutical Vehicles; D011422:Propionates / Q000378:metabolism; D012869:Skin Absorption; D012996:Solutions; D013552:Swine; D013556:Swine, Miniature
chemical_list: D002264:Carboxylic Acids; D014677:Pharmaceutical Vehicles; D011422:Propionates; D012996:Solutions; C029658:propionic acid