Free Radical Scavenging Activity of Drops and Spray Containing Propolis-An EPR Examination.

The influence of heating at a temperature of 50 °C and UV-irradiation of propolis drops and spray on their free radical scavenging activity was determined. The kinetics of interactions of the propolis samples with DPPH free radicals was analyzed. Interactions of propolis drops and propolis spray with free radicals were examined by electron paramagnetic resonance spectroscopy. A spectrometer generating microwaves of 9.3 GHz frequency was used. The EPR spectra of the model DPPH free radicals were compared with the EPR spectra of DPPH in contact with the tested propolis samples. The antioxidative activity of propolis drops and propolis spray decreased after heating at the temperature of 50 °C. A UV-irradiated sample of propolis drops more weakly scavenged free radicals than an untreated sample. The antioxidative activity of propolis spray increased after UV-irradiation. The sample of propolis drops heated at the temperature of 50 °C quenched free radicals faster than the unheated sample. UV-irradiation weakly changed the kinetics of propolis drops or spray interactions with free radicals. EPR analysis indicated that propolis drops and spray should not be stored at a temperature of 50 °C. Propolis drops should not be exposed to UV-irradiation.

Vital dyes and light sources for chromovitrectomy: comparative assessment of osmolarity, pH, and spectrophotometry.

PURPOSE: To investigate the in vitro pH, osmolarity, spectral, and photostability properties of nine vital dyes for vitreoretinal surgery. METHODS: Nine dyes-indocyanine green (ICG), trypan blue (TB), brilliant blue (BriB), bromophenol blue (BroB), Congo red (CR), light green (LG), fast green (FG), indigo carmine (IC) and Evans blue (EB)-diluted in three solvents (saline solution, glucose 5%, and water) were tested for osmolarity and pH. Spectrophotometry was used to determine absorbance properties of 27 solutions. Irradiance emission spectra of seven endoillumination light sources and fiber-optics were compared with dye absorbance curves. RESULTS: Dye osmolarity in saline solution and glucose 5% varied widely (257-385 mOsm) and was lower (0-54 mOsm) when dyes were dissolved in water. Dyes diluted in three solvents showed pH values varying from 2.6 to 9.85. ICG, LG, TB, BroB, CR, and IC demonstrated different absorbances, depending on the solvent. BriB and FG showed similar absorbance curves with different solvents. Spectrophometric analysis showed that all dyes except ICG had remarkable spectral overlap with the light sources. Among endoillumination fiber-optics, overlap was greatest with dual-output illumination with an integrated laser pathway and least with a mercury vapor lamp. CONCLUSIONS: Vital dyes showed variable osmolarity and pH, which also depended on the solvent used. Interaction of light from endoillumination source and vital dye may increase or decrease the risk for toxicity, making appropriate selection of both a desirable way to minimize the risk for phototoxic effects.

Development of in situ thermosensitive drug vehicles for glaucoma therapy.

The goal of this research was to design thermosensitive drug vehicles for glaucoma therapy. Thermosensitive ophthalmic drop was prepared by mixing linear poly(N-isopropylacrylamide-g-2-hydroxyethyl methacrylate) (PNIPAAm-g-PHEMA), PNIPAAm-g-PHEMA gel particles and antiglaucoma drug. This produced polymeric eyedrop containing the drug epinephrine was a clear solution at room temperature which became a soft film after contacting the surface of cornea. The drug entrapped within the tangled polymer chains was therefore released progressively after topical application. Evaluation of the drug release responded as a function of crosslinking density and PHEMA macromer contents. The in vivo studies indicated that the intraocular pressure (IOP)-lowering effect for a polymeric eyedrop lasted for 26 h, which is significantly better than the effect of traditional eyedrop (8 h). Hence our investigations successfully prove that the thermosensitive polymeric eyedrop with ability of controlled drug release exhibits a greater potential for glaucoma therapy.

Determination of assay and impurities of gamma irradiated chloramphenicol in eye ointment.

A sample preparation method was developed to isolate chloramphenicol and its radiolytic products from an oily ointment base. The isolation method suspended the eye ointment in n-hexane at 45 degrees C, and isolated the target compounds as residue by centrifugation. It was found that the main element to ensure a satisfactory isolation was keeping the sample solution at 45 degrees C during sample preparation. Linearity, precision, accuracy and suitability of the method were confirmed valid for both assay and impurity tests. This isolation method was ideal for assay, unique for extraction of unexpected and complex radiolysis products, and had a number of advantages compared to the pretreatment methods described in The United Stares Pharmacopoeia and British Pharmacopoeia, in terms of accuracy, precision, and easy handling. The effect of gamma-irradiation on chloramphenicol eye ointment was studied by HPLC, after applying the developed sample preparation method. The present assay and impurity test methods with HPLC were confirmed to be suitable for irradiated chloramphenicol in eye ointment. Formation of radiolytic products induced by gamma-irradiation was evidenced by the impurity test. The assay test showed that active ingredient of chloramphenicol eye ointment decreased by 3.3% at an irradiation dose of 25 kGy and by 11.1% at 50 kGy.

Interaction between infrared radiation and vitreous substitutes.

OBJECTIVE: To characterize the interaction between midintrared radiation of cutting lasers used or proposed for vitreoretinal surgery and fluid vitreous substitutes commonly used in vitreoretinal surgery. METHODS: Optical transmittance of vitreous substitutes was measured with a double-beam spectrophotometer. Measurements were performed in a wide spectral range of infrared radiation, including the 2120-nm wavelength of the holmium-YAG laser and the water absorption peaks at 1440, 1930, and 2940 nm. RESULTS: The wavelengths considered have a penetration depth varying from 410 to 1 microns in Ringer's solution, balanced salt citrate-buffered solution, balanced salt bicarbonated-buffered solution, hyaluronate sodium, and hydroxypropyl methylcellulose ophthalmic solution, from 2000 to 13 mm in perfluorocarbon liquid, and from 52 to 2.5 mm in silicone and fluorosilicone oils. CONCLUSIONS: Midinfrared optical radiation exhibits dramatic differences of penetration depth in different vitreous substitutes. High-absorbing liquids should be used mainly with contact laser procedures and could provide a shield for remote structures. Low-absorption vitreous substitutes allow noncontact laser surgical procedures, but they also may cause direct optical damage to remote tissues. The knowledge of wavelength transmittance of vitreous substitutes is necessary to evaluate and optimize the efficacy and safety of cutting laser sources.

[Decomposition of chloramphenicol in eyedrops--irritation in the eyes]. / Spaltning av kloramfenikol i øyedråper--svie i øynene.

Chloramphenicol single dose eyedrops 0.5% (Nycomed Pharma) have been found to be very sensitive to exposure to light. We could detect approximately 15% decomposition after six hours of exposure to diffuse daylight. One of the decomposition products is the extremely irritant dichloroacetic acid. This may explain why some patients complain of a burning sensation in the eyes. In one of the samples of light yellow eyedrop received together with the complaints our analysis revealed 17% of the end-cleavage product p-nitrobenzaldehyde. The Norwegian Medicines Control Authority will suggest to the producers of these preparations that they market the product in special light-proof containers.