RELEASE KINETICS OF TRETINOIN FROM DERMATOLOGICAL FORMULATIONS

Tretinoin, or retinoic acid, can be used in the treatment of a variety of skin diseases, depending on its concentration. Formulations contai ning tretinoin 1% have been used in the therapy of malignant cutaneous diseases, namely, Kaposi's syndrome. In lower concentrations, it has been used in antiacne formulations and in the treatment of anti-aging effects on photodamaged skin. The aim of the present study was to dete rmine the variation profile of in vitro release of tretinoin, in order to establish the drug's partition coefficient between its carrier and the stratum corneum. The samples studied were formulations of tretino in 0,05% in carbopol 940 (a synthetic polymer), sodium carboxymethylce llulose (a semisynthetic polymer), and carob gum (a natural polymer) g els. The release profiles obtained from these formulations were compar ed to release profiles of tretinoin creams. The formulations studied e xhibited both good chemical and physical stabilities when submitted to rheological determinations, pH measurements, and drug dosage, through out a 6-month period. The obtained results show that identical polymer viscosities result in identical release profiles; however, the releas e kinetics of tretinoin varies strongly in the way in which the drug i s incorporated in the formulation (whether it is a solution or a suspe nsion).