title: Improvement of clonazepam release from a Carbopol hydrogel.
abstract: The performance of Tween 80, Tween 60, oleic acid, oleyl alcohol and Azone as enhancers of clonazepam permeation from a Carbopol hydrogel through a cellulose nitrate membrane was investigated. The effect of incorporating methyl beta-cyclodextrin (DS 1.8) in combination with clonazepam as a solid phase into some vehicles was also tested. In vitro release studies were carried out with a Sartorius apparatus and the following parameters were evaluated: drug solubility in the vehicle; partition coefficient of the drug between lauryl alcohol (the solvent which impregnates the membrane) and the vehicle; steady state flux; permeability constant; diffusion coefficient; lag time. The release kinetics followed a nearly zero-order pattern, although the diffusion-controlled mechanism might also have been operative. Maximum drug release (2.5 times that of the gel base) was achieved for the formulation containing clonazepam and methyl beta-cyclodextrin in a 1:1 (mol/mol) ratio as a solid phase, in a vehicle composed of water, propylene glycol, Tween 80 and Azone at a mass fraction of 43%, 50%, 2% and 5%, respectively.
authors.affiliation: Dipartimento di Scienze Farmaceutiche, Università di Firenze, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Mura
authors.forename: G P
authors.initials: GP
authors.lastname: Bettinetti
authors.forename: A
authors.initials: A
authors.lastname: Liguori
authors.forename: G
authors.initials: G
authors.lastname: Bramanti
mesh_terms: D000180:Acrylic Resins; D002998:Clonazepam / Q000008:administration & dosage / Q000737:chemistry*; D003692:Delayed-Action Preparations; D005079:Excipients; D011145:Polyvinyls
chemical_list: D000180:Acrylic Resins; D003692:Delayed-Action Preparations; D005079:Excipients; D011145:Polyvinyls; C006912:carboxypolymethylene; D002998:Clonazepam