Effect of Carbon Chain Length, Ionic Strength, and pH on the In Vitro Release Kinetics of Cationic Drugs from Fatty-Acid-Loaded Contact Lenses.

This paper explores the use of fatty acids in silicone hydrogel contact lenses for extending the release duration of cationic drugs. Drug release kinetics was dependent on the carbon chain length of the fatty acid loaded in the lens, with 12-, 14- and 18-carbon chain length fatty acids increasing the uptake and the release duration of ketotifen fumarate (KTF) and tetracaine hydrochloride (THCL). Drug release kinetics from oleic acid-loaded lenses was evaluated in phosphate buffer saline (PBS) at different ionic strengths ( = 167, 500, 1665 mM); the release duration of KTF and THCL was decreased with increasing ionic strength of the release medium.

Evaluation of commercial soft contact lenses for ocular drug delivery: A review.

Soft contact lenses have generated growing interest in ocular drug delivery due to their potential to enhance drug bioavailability in ocular tissues. Commercially available soft contact lenses offer several advantages for ocular drug delivery as they are manufactured on a large scale, which guarantees the availability of a consistent and reproducible product, and their favorable safety profile is well-established through broad clinical use. Here we review the rationale for using commercially available soft contact lenses for ocular drug delivery; summarize the evolution of the materials used in contact lens fabrication; and explore various methods used to improve the drug release characteristics and its tissue penetration.

Extended delivery of cationic drugs from contact lenses loaded with unsaturated fatty acids.

This paper describes the use of surface-active anionic unsaturated fatty acids in commercial contact lenses to extend drug release duration and regulate delivery dosage. We studied the effect of oleic acid on the in vitro release kinetics of three cationic drugs, and two anionic drugs from silicone hydrogel contact lenses. The release duration of the cationic drugs: tetracaine hydrochloride, bupivacaine hydrochloride, and ketotifen fumarate was significantly extended from less than a day to more than a month because of the presence of oleic acid in the contact lenses.

Hydrogel-based ocular drug delivery systems for hydrophobic drugs.

Conventional ophthalmic dosage forms such as eye drops pose a significant challenge because physiological barriers and clearance mechanisms limit ocular bioavailability. Hydrogels are promising therapeutic materials for ocular drug delivery because of their high biocompatibility and their ability to hold and release therapeutic agents. Even though they are generally associated with the delivery of hydrophilic drugs, several approaches have been developed to integrate hydrophobic ophthalmic drugs into hydrogels.

Formation of Drug-Participating Catanionic Aggregates for Extended Delivery of Non-Steroidal Anti-Inflammatory Drugs from Contact Lenses.

This paper focuses on extending drug release duration from contact lenses by incorporating catanionic aggregates. The aggregates consist of a long-chain cationic surfactant, i.e.

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

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.

Extended delivery of non-steroidal anti-inflammatory drugs through contact lenses loaded with Vitamin E and cationic surfactants.

The purpose of this study is to extend drug release from ACUVUE Oasys® and ACUVUE TruEye® silicone hydrogel contact lenses by incorporation of vitamin E in conjunction with a cationic surfactant. In ACUVUE Oasys® and ACUVUE TruEye®, the release of ketorolac tromethamine and flurbiprofen sodium is extended from hours to several days for 11% and 21% vitamin E, (weight of vitamin E / weight of dry lens) but with a considerable reduction in the amount of drug released. Cetalkonium chloride and stearylamine increased the drug loading capacity which was otherwise compromised by the addition of vitamin E in the contact lenses.

Synthesis of silica-alginate nanoparticles and their potential application as pH-responsive drug carriers.

Composite silica-alginate nanoparticles were prepared via silica sol-gel technique using a water-in-oil microemulsion system. In our system, cyclohexane served as the bulk oil phase into which aqueous solutions of sodium alginate were dispersed as droplets that confined nanoparticle formation after addition of tetraethylorthosilicate (TEOS). Our studies showed that much of the particle growth is completed within the first 24 hours and reaction times up to 120 hours only resulted in an additional 5% increase in particle diameter.

Immobilized thermolysin for highly efficient production of low-molecular-weight protamine--an attractive cell-penetrating peptide for macromolecular drug delivery applications.

Macromolecules present a remarkable potential as future therapeutics. However, their translation into clinical practice has been hampered by an inherently low bioavailability. Cell-penetrating peptides (CPP) have been recently shown to significantly improve on the bioavailability of macromolecules.

Use of surface plasmon-coupled emission for enhancing light transmission through Top-Emitting Organic Light Emitting Diodes.

In this paper, we perform surface plasmon-coupled emission studies on Rhodamine 6G molecules embedded in a corrugated structure of a thin film composed of fluorinated silica particles, and a binding medium. Our results show enhancements of photoluminescence due to surface corrugation. By varying the size of the fluorinated silica nanoparticles we were able to control the surface correlation length scale of the corrugated surface structure.