Effect of a Cationic Surfactant on Microemulsion Globules and Drug Release from Hydrogel Contact Lenses

Abstract

The present study evaluates the in vitro release of diclofenac sodium (DFNa) from contact lenses based on poly-2-hydroxyethyl methacrylate (pHEMA) hydrogels containing an embedded microemulsion to extend release duration. The oil (ethyl butyrate)-in-water microemulsion systems are prepared with two non-ionic surfactants, Brij 97 or Tween 80, together with a long-alkyl chain cationic surfactant, cetalkonium chloride (CKC). Without CKC, Brij 97 or Tween 80-based microemulsions showed average droplet sizes of 12 nm and 18 nm, respectively. The addition of CKC decreased the average droplet sizes to 2–5 nm for both non-ionic surfactants. Such significant reduction in the average droplet size corresponds to an increase in the DFNa release duration as revealed by the in vitro experiments. Contact lens characterization showed that important properties such as optical transparency and water content of Brij 97-based contact lenses with cationic microemulsions was excellent. However, the optical transparency of the corresponding Tween 80 based contact lenses was unsatisfactory. The results indicate that cationic microemulsion-laden contact lenses can benefit from combinatory effects of microemulsions and cationic surfactant at low CKC weight percentage, e.g., with the release of 70% of the drug in 45, 10, and 7 h for B97-CKC-0.45%, CKC-0.45%, and control lenses, respectively. However, the microemulsion effect on extending DFNa release became negligible at the highest CKC weight percentage (1.8%).

Novel Ocular Drug Delivery Systems: An Update on Microemulsions

“…25 Isopropyl myristate [36][37][38] and nature oils 39 such as olive oil, 40 castor oil, 39,41 and coconut oil, 39 oleic acid, and triacetin have been widely applied for the development of ocular MEs. Nonionic surfactants such as sugar ester surfactants and polysorbates such as Tween 60 and Tween 80 37,38,40,42 are widely used in ocular delivery since they lack toxicity and irritation. Zwitterionic surfactants such as phospholipids are also applied in MEs.…”

“…4). 42 Dexamethasone is widely used for the reduction of inflammation and the management of acute and chronic eye disorders such as uveitis. Hence, dexamethasone-loaded O/W MEs based on oily phase (isopropyl myristate), the surfactant (Cremophor EL), and the water phase were developed and characterized.…”

“…Control represents the PHEMA contact lenses loaded with diclofenac, whereas B97-CKC-1.8% represents PHEMA contact lenses loaded with diclofenac MEs. Reprinted from Torres-Luna et al 42 CKC, cetalkonium chloride.…”

In vitro study of drug release from various loaded polyurethane samples and subjected to different non-pulsed flow rates

“…Indeed, the release of the drug away from the release surfaces, the water or the medium, takes longer to migrate through the thickness of the polymer [2,35]. This study is applicable in all cases of drug delivery as stents, ear pads, patches, and contact lenses [6,34,[36][37][38][39][40][41]. In all these cases, some parameters have importance like the geometry of the drug holders, glass transition temperature, viscosity, drug percentage, drug type, coating thickness, and release kinetics [6,28].…”

Special Issue on Designing Hydrogels for Controlled Drug Delivery: Guest Editors’ Introduction

“…This special issue fits into this context and has the aim of describing, through seven research papers and two review articles, recent studies concerning the design, preparation and evaluation of the performance of hydrogels for the controlled delivery of drugs.In the first article Cesar Torres-Luna and collaboarators evaluated the in vitro release of diclofenac sodium, an anionic drug useful for the treatment of pain and eye inflammation, from contact lenses based on poly-2-hydroxyethyl methacrylate hydrogels containing an embedded microemulsion. In particular, the aim of the work was to extend the release duration of the diclofenac sodium [1]. The oil in water microemulsion systems were prepared with two non-ionic surfactants, Brij 97 or Tween 80 and cetalkonium chloride as cationic surfactant.…”