Evaluation of transcutol as a clonazepam transdermal permeation enhancer from hydrophilic gel formulations

• Published in: European journal of pharmaceutical sciences 2000-02, Vol.9 (4), p.365-372
• Main Authors: Mura, P, Faucci, M.T, Bramanti, G, Corti, P
• Format: Article
• Language: English
• Subjects: Administration, Cutaneous; Animals; Anticonvulsants - administration & dosage; Anticonvulsants - pharmacokinetics; Artificial lipophilic membrane; Biological and medical sciences; Carbopol hydrogel; Chemistry, Pharmaceutical; Clonazepam; Clonazepam - administration & dosage; Clonazepam - pharmacokinetics; Enhancer activity; Ethylene Glycols - pharmacology; Gels; General pharmacology; Hypnotics. Sedatives; In Vitro Techniques; Male; Medical sciences; Neuropharmacology; Permeability; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Propylene Glycol - pharmacology; Psychology. Psychoanalysis. Psychiatry; Psychopharmacology; Rabbit ear skin; Rabbits; Rheology; Skin Absorption - drug effects; Solubility; Transcutol
• ISSN: 0928-0987; 1879-0720
• DOI: 10.1016/S0928-0987(99)00075-5

The influence of diethyleneglycol monoethyl ether (transcutol), alone or in combination with propylene glycol, on clonazepam permeation through an artificial membrane and excised rabbit ear skin from Carbopol hydrogels was investigated. Drug kinetic permeation parameters were determined for both series of experiments and compared. Rheological characteristics, drug solubility and membrane/vehicle partition coefficient for each gel formulation were also determined, and their role in the formulation performance was investigated. Both series of experiments showed an increase of drug permeation as a function of transcutol content in the formulation. The combination of transcutol and propylene glycol resulted in a synergistic enhancement of clonazepam flux. A different trend was found in experiments with gels containing mixtures of the two enhancers, where an increase (in the case of artificial membrane) or a decrease (in the case of rabbit ear skin) of drug permeation was found by increasing the transcutol/propylene glycol ratio in the mixture. Such a result is explained on the basis of the particular mechanism of action demonstrated for transcutol which associates the increase of drug solubility to the potent effect of a depot in the skin.