Combining modeling of drug uptake and release of cyclosporine in contact lenses to determine partition coefficient and diffusivity

Preparation of a Regioselective Quercetin-3-palmitate and Its Using for Boosting Cooking Oil Stability

Due to over worldwide use of frying oil, and due to its oxidation and deterioration after the usage for short time, huge oil amounts are wasted. So, most attempts are aimed to increase oil stability. Quercetin is a common name for the lipophobic strong natural phenolic antioxidant 2-(3,4-Dihydroxyphenyl)-5,7-dihydroxy-4H-1-benzopyran-4-one. Thus, its solubility had been improved by converting it to a lipophilic compound via its appending to a fatty acid residue. So, regioselectively 2-(3,4-Dihydroxyphenyl)-5,7-dihydroxy-3-[Hexadecanyl]oxychromen-4-one commonly named as (Quercetin-3-palmitate) was synthesized. The formed compound was confirmed based on its elemental analysis and spectral data (IR, ¹H NMR and MS). The partition coefficient of Quercetin-3-palmitate in octanol/water (k) was determined and compared to that of palmitic acid and quercetin individually to prove its solubility enhancement. Its radical scavenging activity was then tested. The effect of this new antioxidant compound on the oil stability was studied through the frying process. All physical and chemical parameters of this oil were considered before and after the frying process compared to another reference antioxidant (TBHQ) and control sample. The safety of this compound was determined by acute oral toxicity using albino mice. The liver and kidney functions of these mice were also examined. The results showed non-significant change. A sensory evaluation of the fried potato chips has been done. The results showed that the properties of the potato chips were improved by adding Quercetin-3-palmitate to the oil. Thus, good protection against frying oils oxidation was achieved via the addition of Quercetin-3-palmitate. The Quercetin-3-palmitate effectiveness is mainly attributed to its stability at high temperatures. Moreover, Quercetin-3-palmitate was found to be a safe compound according to an acute lethal toxicity test. Consequently, it can be used as a food additive.

Transport of Vitamin E from Ethanol/Water Solution into Contact Lenses and Impact on Drug Transport

Purpose: Contact lens-based drug delivery has many advantages over eye drops including higher bioavailability and sustained release. Commercial contact lenses release drug rapidly necessitating integration of control-release mechanisms into the lenses such as incorporation of vitamin E diffusion barriers. In prior publications, vitamin E barriers are loaded by placing the lenses in vitamin E-ethanol solution, followed by the ethanol extraction. In this article, we investigate feasibility of manufacturing vitamin E barriers by soaking contact lenses in vitamin E dissolved in ethanol-water solutions to minimize swelling. Methods: Contact lenses are soaked in solutions of vitamin E dissolved in ethanol-water mixtures. The dynamics of vitamin E transport into the measured and fitted to diffusion equation to determine diffusivity and partition coefficient. Vitamin E loaded lenses are imaged and transport of hydrophilic drug timolol is measured. Results: The partition coefficient of vitamin E increases more than 5 and 10-fold when the water content in the loading solution reaches 15% and 25% (v/v), respectively. The solubility of vitamin E in the solutions decreases as water fraction increases but the increase in partition coefficient allows for loading > 20% vitamin E in the lens. The barriers manufactured by this approach are effective at sustaining release of glaucoma drug timolol. Conclusions: Vitamin E barriers can be incorporated into contact lenses by soaking in solutions of vitamin E in water and ethanol. Vitamin E barriers extended hydrophilic drug release and the reduced swelling is beneficial in minimizing the possibility of lens damage during loading of vitamin E.