The Permeation of Benzodiazepines through Synthetic Membranes

The permeation of chlordiazepoxide, diazepam, oxazepam, lorazepam, nitrazepam, and nimetazepam through a dimethylpolysiloxane membrane and that of chlordiazepoxide, oxazepam, and nitrazepam through an ethylene-vinyl acetate copolymer membrane were investigated using a newly designed permeation cell. Large permeability values of diazepam and nimetazepam were attributed to their large partition coefficients. Large lag time values of chlordiazepoxide, oxazepam, and nitrazepam through the silicone membrane were rationalized by adsorption of these drugs on silica filler within the silicone membrane. Thus permeation data of these drugs can be interpreted on the basis of their physical properties.