title: Addition of hydrogen bond donating excipients to oil solution: effect on in vitro drug release rate and viscosity.
abstract: In oily vehicles containing different hydrogen bond donating excipients rates of transfer of the weak electrolytes naproxen and lidocaine from the oil phase to the aqueous medium were measured by using the rotating dialysis cell. A logarithmic linear correlation was established between the apparent partition coefficient, P(app), and the first-order rate constant related to attainment of equilibrium between the two phases, k(obs), which fitted well with results from former publications. Further, release data for the non-electrolyte testosterone were found to fit into this linear correlation. Apparent partition coefficients were determined between oil vehicles containing various amounts of hydrogen bond donating excipients and phosphate buffer, pH 6.00, revealing a rise in log P(app) with increasing concentration of excipient. Viscosity was measured for castor oil containing vehicles showing a linear relationship between percentage (v/v) castor oil and log viscosity (mPas) of the mixed vehicle.
authors.affiliation: Department of Analytical and Pharmaceutical Chemistry, The Royal Danish School of Pharmacy, Universitetsparken 2, DK-2100, Copenhagen, Denmark. dola@dfh.dk
authors.forename: D B
authors.initials: DB
authors.lastname: Larsen
authors.forename: K
authors.initials: K
authors.lastname: Fredholt
authors.forename: C
authors.initials: C
authors.lastname: Larsen
mesh_terms: D000779:Anesthetics, Local / Q000737:chemistry*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry*; D005079:Excipients / Q000737:chemistry*; D006860:Hydrogen Bonding; D066298:In Vitro Techniques; D008012:Lidocaine / Q000737:chemistry*; D009288:Naproxen / Q000737:chemistry*; D009821:Oils / Q000737:chemistry*; D012996:Solutions; D014783:Viscosity
chemical_list: D000779:Anesthetics, Local; D000894:Anti-Inflammatory Agents, Non-Steroidal; D005079:Excipients; D009821:Oils; D012996:Solutions; D009288:Naproxen; D008012:Lidocaine