Classification of benzoyl peroxide as safe and effective and revision of labeling to drug facts format; topical acne drug products for over-the-counter human use; final rule

We, the Food and Drug Administration (FDA), are issuing this final rule to include benzoyl peroxide as a generally recognized as safe and effective (GRASE) active ingredient in over-the-counter (OTC) topical acne drug products. In addition, this final rule includes new warnings and directions required for OTC acne drug products containing benzoyl peroxide. We are also revising labeling for OTC topical acne drug products containing resorcinol, resorcinol monoacetate, salicylic acid and/or sulfur to meet OTC drug labeling content and format requirements in a certain FDA regulation. This final rule is part of our ongoing review of OTC drug products and represents our conclusions on benzoyl peroxide in OTC acne drug products.

Tretinoin-loaded nanocapsules: Preparation, physicochemical characterization, and photostability study

The aim of this study was to prepare and characterize tretinoin-loaded nanocapsules as well as to evaluate the influence of this nanoencapsulation on tretinoin photostability. Tretinoin-loaded nanocapsules (0.5 mg ml(-1)) were prepared by interfacial deposition of preformed polymer (poly-epsilon-caprolactone) using two different oily phases: capric/caprylic triglycerides and sunflower seed oil. Tretinoin-loaded nanocapsules presented drug content close to the theoretical value, encapsulation efficiencies higher than 99.9%, nanometric mean size with a polydispersity index below 0.25, and pH values between 5.0 and 7.0. Regarding photodegradation studies, tretinoin methanolic solution showed a half-life time around 40 min according to a first order equation, whereas tretinoin nanocapsule suspensions showed a half-life between 85 and 100 min (twofold higher than in methanolic solution) according to a zero order equation. Tretinoin-loaded nanocapsules improved tretinoin photostability, independently on the type of oily phase used in this study, and represent a potential system to be incorporated in topical or systemic dosage forms containing tretinoin.

UVA is the major contributor to the photodegradation of tretinoin and isotretinoin: Implications for development of improved pharmaceutical formulations

The chemical stability of tretinoin (RA) and isotretinoin (13RA) in ethanol and dermatological cream preparations exposed to solar simulated light (SSL), UVA, and visible light has been studied. Photostability was monitored by an HPLC method that allowed simultaneous analysis of RA and 13RA, thus allowing photodegradation due to isomerization to other retinoids and photolysis to non-retinoid products to be monitored. Both retinoids undergo both isomerization and photolysis following SSL, UVA and visible light exposure but RA is more sensitive to photodegradation than 13RA. Degradation of both retinoids by photolysis is considerably greater in cream formulations than in ethanol and the photodegradation follows second order kinetics. Rate constants and half-lives for degradation of RA and 13RA in ethanol solution and cream preparations subjected to different light sources are reported. The UVA component of SSL is the major contributor to photodegradation. Since UVA penetrates deeply into skin, our results suggest that photodegradation of RA may contribute to the photosensitivity associated with RA therapy. Our studies suggest that development of improved formulations and the use of effective UVA sunscreens may reduce the side effects of RA therapy.

Evaluation of nanoparticles loaded with benzopsoralen in rat peritoneal exudate cells

Psoralens are widely used for the treatment of hyperproliferative skin disease. In this work, we prepared nanoparticles (NP) containing a benzopsoralen (3-ethoxy carbonyl-2H-benzofuro[3,2-f]-1-benzopiran-2-one) by the solvent evaporation technique. We evaluated important NP parameters such as particle size, drug encapsulation efficiency, effect of the encapsulation process over the drug's photochemistry, zeta potential, external morphology, and in vitro release behavior. We also investigated the nanoparticle as a drug delivery system (DDS), as well as its target delivery to the action site, which is a very important parameter to increase the therapeutic use of psoralens and to reduce their side effects. The uptake of benzopsoralen-loaded PLGA nanoparticles by different kinds of cells found in rat peritoneal exudates was also studied. The photodamage promoted by irradiation with UV light revealed morphological characteristics of cell damage such as cytoplasmic vesiculation, mitochondrial damage, and swelling of both the granular endoplasmatic reticulum and nuclear membrane. This encapsulation method maintained the drug's properties and improved drug delivery to the target cell.

Fluorescent and non fluorescent C4-cycloadducts in the photoreaction at 365 nm between psoralen-3H and DNA

In the C4-photocycloaddition at 365 nm between 3H-psoralen and native DNA, the furocoumarin reacts with the pyrimidine bases of the macromolecule mostly in the 4′-5′-positions (fluorescent photocompounds). The non-fluorescent cycloadditions (addition in the 3—4 position) form in a ratio of 1: 3 compared with the preceding ones.