Porous Silicon as a drug delivery system for tretinoin

SINICO, CHIARA;MULA, GUIDO;Setzu S.;CADDEO, CARLA;Demontis V.;MANCONI, MARIA;FADDA, ANNA MARIA

2005-01-01

---

Abstract

Tretinoin is a natural retinoid widely used in proliferative and inflammatory skin diseases, such as psoriasis, acne and skin cancer. Due to the severe side effects when systematically administered, tretinoin is almost exclusively topically employed. However, even its topical application is limited by several drawbacks, such as skin irritation, very low solubility and high instability in the presence of air, light and heat. Porous silicon is a material with a very high specific surface area, reaching 900m2/cm3 when the pore size is a few nanometers in diameter. This property makes this material very interesting in the applications of drug delivery systems, since the molecules can be absorbed over very large surfaces even for small samples sizes. The aim of this work is to evaluate the potential of porous silicon as a topical delivery system capable of improving the photostability of tretinoin. Porous silicon layers were realised by electrochemical etching of bulk crystalline silicon. Drug loading was achieved by soaking 6.6 mg of the matrix in a solution of tretinoin (0.05% or 0.1%) for 1 day at room temperature, under continuous stirring. To determine the amount of drug loaded into the porous material (approximately 13% w/w%), impregnated samples were dispersed in methanol and kept under constant stirring for 2 days. The amount of drug released after 24 h was almost 90%.