Measurement of diffusion coefficients of parabens and steroids in water and 1-octanol.
Diffusion coefficients (D) of parabens and steroids in water and 1-octanol were determined by using the chromatographic broadening method at 37 degrees C, and the relationships between the D values and the physicochemical properties of the drugs were discussed. The D values in 1-octanol were lower than those in water because of the higher viscosity of 1-octanol. The D values depend on not only the molecular weight (MW), but also the lipophilicity of the drugs in water and on the ability for hydrogen-bonding in 1-octanol. When the lipophilic index (LI), calculated from the retention time using in a reverse-phase column, was used as a parameter of drug lipophilicity, the following equation was obtained for D in water (D(w)); log D(w)=-0.215.log MW-0.077.log LI-4.367. When the hydrogen bond index (HI), the logarithm of the ratio of the partition coefficient of the drugs in 1-octanol and cyclohexane, was used as an index of hydrogen-bonding, the following equation was obtained for D in 1-octanol (D(o)); log D(o)=-0.690.log MW-0.074.log HI-4.085.
Seki
Toshinobu
T
Hokkaido College of Pharmacy, Hokkaido, Japan. toseki@hokuyakudai.ac.jp
Mochida
Junko
J
Okamoto
Maiko
M
Hosoya
Osamu
O
Juni
Kazuhiko
K
Morimoto
Kazuhiro
K
D020003:1-Octanol / Q000737:chemistry*; D004058:Diffusion; D006860:Hydrogen Bonding; D008956:Models, Chemical; D010226:Parabens / Q000737:chemistry*; D013256:Steroids / Q000737:chemistry*; D014783:Viscosity; D014867:Water / Q000737:chemistry*
D010226:Parabens; D013256:Steroids; D014867:Water; D020003:1-Octanol