betadex and oxybenzone

There is a serious concern about the topical and systemic absorption of organic ultraviolet filters in sunscreen formulations and subsequent phototoxic and photo allergic reactions. Ideally, a sunscreen should localize in the surface of stratum corneum and create a barrier against UV radiation, but not penetrate into the underlying viable tissues and systemic circulation.. The objective of the present study was to determine the effects of β-cyclodextrin (β-CDX) complexation on the transdermal penetration of 3 commonly used sun blocking agents, Eusolex ® 4360 (avobenzone), Eusolex ® 9020 (Oxybenzone) and Eusolex ® 232 (Ensulizole).. The complexation of the sunscreen agents with β-CDX was performed by 3 methods and confirmed by differential scanning calorimetry (DSC). Sunscreens, and their physical mixtures and complexes with β-CDX were introduced into a model cream base (o/w emulsion). To find out the influence of β-CDX, sunscreen creams were applied to the rat skin in vitro in standard Franz diffusion cells and the amount of sunscreen permeated after 6 h was assessed by HPLC.. The skin penetration flux of the UV filters was significantly reduced (4–15 fold) by complexation with β-CDX. Complexation also could prolong absorption lag time of sun blocking agents to more than 150 min.. Considering the ability of β-CDX complexation in the reduction of flux and enhancement ratio as well as prolongation of absorption lag time, this technique could be very helpful for reducing systemic absorption of the UV filters and subsequent toxicity and allergic reaction.

Topics: Animals; Benzimidazoles; Benzophenones; beta-Cyclodextrins; Chemistry, Pharmaceutical; Male; Rats; Rats, Wistar; Skin Absorption; Sulfonic Acids; Sunscreening Agents

This work is aimed to evaluate the application of photoacoustic spectroscopy (PAS) in the characterization of inclusion complexes of benzophenone-3 (BZ-3) and hydroxypropyl-β-cyclodextrin (HPCD) and to analyze the ex vivo percutaneous penetration of sunscreens and their reaction with the skin. The formation of inclusion complexes of BZ-3 and HPCD was performed by co-precipitation in stoichiometric ratios of 1:1 and 1:2. Thermal analysis and PAS characterized these inclusion complexes, and they indicated that the stoichiometric ratio of 1:2 was best. Sunscreen formulations were prepared and applied on the ears of rabbits. PAS suggested that the formulation with the complex resulted in lower penetration of BZ-3. Histological analysis demonstrated that the use of the formulation with BZ-3 was associated with an increase in the comedogenic effect and the presence of acanthosis, while no such effect was found in the formulation with the complex. The formulation with the BZ-3-HPCD complex is a promising strategy for improving the photoprotective effect of BZ-3. PAS can be used in the study of inclusion complexes with cyclodextrins and the evaluation of the percutaneous penetration of sunscreen formulations. Further tests are being conducted using PAS to monitor in vivo changes in the optical absorption spectra of formulations and to investigate their photostability.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Animals; Benzophenones; beta-Cyclodextrins; Chemistry, Pharmaceutical; Drug Stability; Male; Photoacoustic Techniques; Rabbits; Skin; Skin Absorption; Spectrum Analysis; Sunscreening Agents

The objective of the present study was to determine the effects of hydroxypropyl-beta-cyclodextrin (HPCD) concentration on the transdermal permeation and skin accumulation of a model ultraviolet (UV) absorber, oxybenzone. The concentration of oxybenzone was held constant at 2.67 mg/mL for all formulations, while the HPCD concentrations varied from 0 to 20% (w/w). Complexation of oxybenzone by HPCD was demonstrated by differential scanning calorimetry. A modified Franz cell apparatus was used in the transdermal experiments, with aliquots of the receptor fluid assayed for oxybenzone by high-performance liquid chromatography. From the permeation data, flux of the drug was calculated. Skins were removed from the diffusion cells at specified time points over a 24-hr period and the oxybenzone content in the skin determined. The aqueous solubility of oxybenzone increased linearly with increasing HPCD concentration, following a Higuchi AL-type complexation. The stability constant of the reaction was calculated from the phase-solubility diagram and found to be 2047 M-1. As the concentration of HPCD was increased from 0 to 10%, transdermal permeation and skin accumulation of oxybenzone increased. Maximum flux occurred at 10% HPCD, where sufficient cyclodextrin was added to completely solubilize all oxybenzone. When the concentration of HPCD was increased to 20%, both transdermal permeation and skin accumulation decreased. These data suggest the formation of a drug reservoir on the surface of the skin.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Administration, Cutaneous; Animals; Benzophenones; beta-Cyclodextrins; Calorimetry, Differential Scanning; Cyclodextrins; Dose-Response Relationship, Drug; Excipients; In Vitro Techniques; Mice; Mice, Hairless; Permeability; Skin; Skin Absorption; Solubility; Solvents; Sunscreening Agents; Thermodynamics; Time Factors; Water