Preliminary Study Regarding the Formulation and Physical Evaluation of Some Biocompatible, Oil in Water Microemulsions With Salicylic Acid for Dermatologic Use

Abstract

Microemulsions (MEs) are considered a piece of new generation colloidal systems with high potential for drug delivery, especially for topical application. The present study had as main objectives the development and physical analysis of two groups of oil in water (O/W) microemulsion (ME) vehicles using a biocompatible mixture composed of lecithin/Tween 80 as surfactants and propylene glycol (PG) as cosurfactant. The addition of vegetable oils and hyaluronic acid (HA) enriched the quality profile of the systems. The vehicles were suitable to entrap salicylic acid (SA) 0.5% as a model drug with keratoplastic properties, and positive outcomes in acne treatment. The study was divided in two stages of screening, resulting two groups of MEs. In the first case, lecithin was tested as potential surfactant on a domain of 0.5 -2%. A minimum amount of lecithin 0.5%, in association with Tween 80 and PG was considered appropriate to obtain the second group of O/W MEs. In this case, were screened combinations of lecithin/Tween 80/PG able to solubilize SA 0.5% and small quantities of vegetable oils. All the microdispersions obtained in both stages were analysed considering visual appearance, conductivity, pH and refractive index as important parameters for systems' stability. The area of MEs generation for the second group, was specifically identified using graphical method. An extensive rheological analysis was considered to determine the flow behaviour for the most representative systems. It was concluded that minimal concentration of tensioactives that can promote stable and clear systems with SA was 30.5%. This proportion was specific for a ME system formulated with 20% Tween 80, 10%PG and 0.5% lecithin. Physical analysis performance emphasized preliminary data concerning the internal structure of microemulsions, offering a useful background for future studies. RezumatMicroemulsiile (MEs) reprezintă formulări ce aparţin noii generaţii de sisteme coloidale, cu înalt potenţial pentru cedarea medicamentului, în special pentru administrarea topică. Prezentul studiu a avut ca obiective principale dezvoltarea şi analiza fizică a două grupe de vehicule de tip microemulsie (ME) ulei în apă (U/A), utilizând un amestec biocompatibil format din lecitină/Tween 80 ca surfactanţi, alături de propilenglicol (PG) cu funcţie de cosurfactant. Au fost adăugate uleiuri vegetale şi acid hialuronic (HA), cu scopul de a îmbunătăţi profilul calitativ al sistemelor. Vehiculele formulate au fost adecvate pentru încorporarea acidului salicilic (SA) 0,5% ca medicament model cu proprietăţi keratoplastice și efecte pozitive în tratamentul acneei. Studiul a fost împărțit în două etape de screening, rezultând două grupe de microemulsii. În prima etapă, lecitina a fost testată ca potențial surfactant pe un domeniu de 0,5 -2%. Utilizarea lecitinei 0,5%, alături de Tween 80 și PG, a fost considerată potrivită pentru obținerea celui de-al doilea set de sisteme U/A. În acest caz, au fost testate combinații conținând lecitină/Tween 80/PG, capabile să solubilize...

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Insights from a Box–Behnken Optimization Study of Microemulsions with Salicylic Acid for Acne Therapy

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