Control of transdermal permeation of hydrocortisone acetate from hydrophilic and lipophilic formulations

Abstract

The purpose of this research was the preparation of four formulations containing hydrocortisone acetate (HCA) for topical application, including two aqueous systems (hydrophilic microemulsion and aqueous gel) and two systems with dominant hydrophobicity (hydrophobic microemulsion and ointment). The formulations were tested for the release and permeation of HCA across an animal membrane. The release of HCA was found comparable for the four systems. The two microemulsions promote permeation across an ex-vivo membrane, examined by means of a Franz cell. Hydrophobic microemulsion guarantees the highest solubility (2,370 microg/ml) and flux (133 microg/cm(2).h) of the drug, since it contains almost 40% Transcutol, a permeation enhancer. Gel and ointment provide lower solubility and flux, being the values, related to the ointment, the lowest ones (562 microg/ml and 0.4 microg/cm(2).h). Experimental results allow the conclusion that gel and ointment can be suitable when it is desirable to minimize absorption of topically applied HCA as to keep the drug restricted to the diseased area and prevent side effects of the systemic presence of HCA.

Fig. 1

HCA release profiles from the four formulations: unfilled triangle hydrophilic microemulsion; unfilled square aqueous gel; filled diamond lipophilic microemulsion; filled square ointment

Fig. 2

Relationship between HCA amount released after 24 h from the four formulations and solubility

Fig. 3

HCA Permeation profiles from: unfilled triangle hydrophilic microemulsion (A); filled diamond lipophilic microemulsion (C)

Fig. 4

Permeation profiles of HCA from: unfilled square aqueous gel (B); filled square ointment (D)