title: Reaction plane approach for estimating the effects of buffers on the dissolution rate of acidic drugs.
abstract: A mass transfer model was developed to describe the dissolution and reaction of an acidic drug, naproxen [(+)-6-methoxy-alpha-methyl-2-naphthaleneacetic acid], from a rotating disk in buffered solutions. Dissolution in 0.0010 to 0.030 M acetate, citrate, and phosphate buffer solutions, with 0.1 M KCl added, over a pH range of 2 to 8 at 25 degrees C, was investigated. Features of the mass transfer model include: treatment of the mass transfer as a convective diffusion process; use of the buffer reactions and the acid ionization as a single flux boundary condition; the capacity to make accurate a priori predictions without fitting film thicknesses or diffusion coefficients; and the option of considering two limiting cases for the maximal increase in dissolution that could be expected in a reactive buffer and the increase in dissolution in a buffer at maximum buffer capacity.
authors.affiliation: College of Pharmacy, University of Michigan, Ann Arbor 48109-1065.
authors.forename: D P
authors.initials: DP
authors.lastname: McNamara
authors.forename: G L
authors.initials: GL
authors.lastname: Amidon
mesh_terms: D002021:Buffers; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004058:Diffusion; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009288:Naproxen / Q000032:analysis; D004364:Pharmaceutical Preparations / Q000032:analysis*; D012995:Solubility
chemical_list: D002021:Buffers; D004364:Pharmaceutical Preparations; D009288:Naproxen