Photochemical and oxidative degradation of the solid-state tretinoin tocoferil

Fabrication and characterization of tretinoin-loaded nanofiber for topical skin delivery

Background

Tretinoin or all-trans retinoic acid is used in the treatment of acne vulgaris and photo-aging. This work aims to develop tretinoin-loaded nanofibers as a potential anti-acne patch and to investigate its physicochemical characteristics.

Method

Nanofibers were produced via electrospinning method and surface topography was evaluated by Field Emission Scanning Electron Microscopy (FESEM). The functional groups of polymer and the drug molecule and the possible interactions were studied by Fourier Transform Infrared Spectroscopy (FTIR). Drug release studies were carried out by total immersion method at 25 °C and 32 °C. Tretinoin stability was evaluated at room temperature and fridge for 45 days. The possibility of synergistic antibacterial activity of tretinoin and erythromycin combination was investigated on Staphylococcus aureus (ATCC® 25923™) and (ATCC® 29213™) by Kirby Bauer disc diffusion method.

Results

Uniform fibers without drug crystals were fabricated via electrospinning. Drug-loaded nanofibers show inherent stability under various storage conditions. Electrospun nanofibers showed a prolonged release of tretinoin. The stability of formulations in FT was higher than RT. Disc diffusion tests did not show any synergism in the antibacterial activity of erythromycin when used in combination with tretinoin.

Conclusion

It can be anticipated that the easy fabrication, low costs and dosing frequency of the construct reported here provide a platform that can be adapted for on-demand delivery of tretinoin.

Graphical abstract

Photostability testing using online reactor HPLC hyphenation and mass spectrometric compound identification illustrated by ketoprofen as model compound

Investigations on the photochemical stability of pharmaceutical substances are mandatory in drug development and licensing as photo-induced degradation of an active pharmaceutical ingredient (API) may not only lead to decreased API concentrations but also to toxic or reactive products. Thus, the US Food and Drug Administration (FDA) and the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) issued Guidance for Industry Q1B "Photostability Testing of New Drug Substances and Products" for testing of pure but also packed drugs. However, photoproducts are also known to be generated in vivo under sunlight exposure of the skin and lead to considerable amounts of adverse drug effects. Herein we present an alternative system that may be used for photostability testing mimicking both situations. It combines a tailored photoreactor with an exchangeable pen light source and a modified HPLC system with online-SPE. Identification of photoproducts may be performed using mass spectrometry. The potential of accurate mass spectrometry as a tool for identification of photoproducts was demonstrated as well. A comparison of the online photoreactor system and the traditional photochamber irradiation was performed using ketoprofen for proof of concept. In both designs acetylbenzophenone and ethylbenzophenone were detected as main photoproducts. The new device allows for fast and easy photostability studies that may help to reduce time consuming in vitro experiments and animal trials. Using state of the art instruments kinetic studies could also easily be performed with qualitative and quantitative perspectives combined into one experimental design with only very low amounts of API needed. This may be useful in early drug development, where only small amounts of API are available. Scale-up may also be easily realized for the generation of reference material for quantification and quality control (QC) processes as well as for toxicity testing.

Effect of X-ray exposure on the pharmaceutical quality of drug tablets using X-ray inspection equipment

CONTEXT

X-ray inspection equipment is widely used to detect missing materials and defective goods in opaque containers. Its application has been expanded to the pharmaceutical industry to detect the presence of drug tablets in aluminum foil press-through packaging. However, the effect of X-rays on the pharmaceutical quality of drug tablets is not well known.

OBJECTIVE

In this study, the effect of X-rays on the pharmaceutical quality of drug tablets was investigated.

METHODS

Exposure of acetaminophen, loxoprofen and mefenamic acid tablets to X-ray doses of 0.34 mGy (thrice the dose by X-ray scanning) to 300 Gy (maximum dose from our X-ray equipment) was demonstrated, and the samples were evaluated by formulation tests.

RESULTS

Exposure to X-rays did not affect the pharmaceutical quality of the drug content. The samples exposed to X-rays exhibited almost the same profile in formulation tests (dissolution test, disintegrating test and hardness test) as control samples (0 Gy). The combination of X-ray exposure with accelerated temperature and humidity tests (six months) also did not affect the pharmaceutical quality. The color change of light-sensitive drugs (nifedipine and furosemide tablets) after X-ray exposure was negligible (< 1.0). In contrast, tablet color was remarkably changed by light from a D65 lamp.

CONCLUSION

The X-ray scanning and X-ray exposure under our experimental conditions did not affect the pharmaceutical quality of drug tablets.

Implications of light energy on food quality and packaging selection

Light energy in the ultraviolet and visible light regions plays a critical role in overall food quality, leading to various degradation and oxidation reactions. Food degradation and oxidation result in the destruction of nutrients and bioactive compounds, the formation of off odors and flavors, the loss of food color, and the formation of toxic substances. Food compounds are sensitive to various light wavelengths. Understanding the effect that specific light wavelengths have on food compounds will allow the development of novel food packaging materials that block the most damaging light wavelengths to photostability of specific food compounds. Future research should focus more specifically on the effect of specific light wavelengths on the quality of specific food products, as there is limited published information on this particular topic. This information also can be directly related to the selection of food packaging materials to retain both high quality and visual clarity of food products exposed to light.

Urea co-inclusion compounds of 13 cis-retinoic acid for simultaneous improvement of dissolution profile, photostability and safe handling characteristics

13-cis Retinoic acid (cis-RA), a synthetic retinoid used in the treatment of severe acne, is known to exhibit extremely low aqueous solubility and high photosensitivity. In this study, urea, a well-known adductor for linear compounds, was successfully employed for the adduction of cis-RA — a substituted cyclic organic compound. Formation of urea inclusion compounds was confirmed by FTIR, DSC and XRD. A modified Zimmerschied calorimetric method was employed for the estimation of the minimum amount of rapidly adductible endocyte (RAE) required for adduction of cis-RA in urea. Urea–cis-RA-RAE inclusion compounds containing varying proportions of guests were prepared and their thermal behaviour studied by DSC. The inclusion compounds were found to have an improved dissolution profile as demonstrated by an overall increase in the dissolution efficiency. An accelerated photostability study, conducted as per Q1B ICH guidelines, revealed that co-inclusion of cis-RA in urea delayed photo-degradation of the drug when compared with that of the pure drug. The results suggest the possibility of exploiting co-inclusion of the drug in a urea host lattice for improved solubility, stability and reduced handling problems for cis-RA.

Effect of light intensity and wavelengths on photodegradation reactions of riboflavin in aqueous solution

A study of the effect of light intensity and wavelengths on photodegradation reactions of riboflavin (RF) solutions in the presence of phosphate buffer using three UV and visible radiation sources has been made. The rates and magnitude of the two major photodegradation reactions of riboflavin in phosphate buffer (i.e., photoaddition and photoreduction) depend on light intensity as well as the wavelengths of irradiation. Photoaddition is facilitated by UV radiation and yields cyclodehydroriboflavin (CDRF) whereas photoreduction results from normal photolysis yielding lumichrome (LC) and lumiflavin (LF). The ratios of the photoproducts of the two reactions at 2.0 M phosphate concentration, CDRF/RF (0.09-0.22) and CDRF/LC (0.54-1.75), vary with the radiation source and are higher with UV radiation than those of the visible radiation. On the contrary, the ratios of LF/LC (0.15-0.25) increase on changing the radiation source from UV to visible. The rate is much faster with UV radiation causing 25% degradation of a 10(-5) M riboflavin solution in 7.5 min compared to that of visible radiations in 150-330 min.

Photodecomposition and phototoxicity of natural retinoids

Sunlight is a known human carcinogen. Many cosmetics contain retinoid-based compounds, such as retinyl palmitate (RP), either to protect the skin or to stimulate skin responses that will correct skin damaged by sunlight. However, little is known about the photodecomposition of some retinoids and the toxicity of these retinoids and their sunlight-induced photodecomposition products on skin. Thus, studies are required to test whether topical application of retinoids enhances the phototoxicity and photocarcinogenicity of sunlight and UV light. Mechanistic studies are needed to provide insight into the disposition of retinoids in vitro and on the skin, and to test thoroughly whether genotoxic damage by UV-induced radicals may participate in any toxicity of topically applied retinoids in the presence of UV light. This paper reports the update information and our experimental results on photostability, photoreactions, and phototoxicity of the natural retinoids including retinol (ROH), retinal, retinoid acid (RA), retinyl acetate, and RP (Figure 1).

Accelerated aging: Prediction of chemical stability of pharmaceuticals

Methods of rapidly and accurately assessing the chemical stability of pharmaceutical dosage forms are reviewed with respect to the major degradation mechanisms generally observed in pharmaceutical development. Methods are discussed, with the appropriate caveats, for accelerated aging of liquid and solid dosage forms, including small and large molecule active pharmaceutical ingredients. In particular, this review covers general thermal methods, as well as accelerated aging methods appropriate to oxidation, hydrolysis, reaction with reactive excipient impurities, photolysis and protein denaturation.

Photoreaction, phototoxicity, and photocarcinogenicity of retinoids

Sunlight is a human carcinogen. Many retinoid-containing cosmetics are used to protect damages caused by sunlight irradiation. Since retinol is thermally unstable and retinyl palmitate (RP) s relatively more stable, RP is also widely used as an ingredient in cosmetic formulations. In general, little is known about the photodecomposition of retinoids and the toxicity of retinoids and their photodecomposition products on the skin's responses to sunlight. This review focuses on the update information on photoreactions, phototoxicity, and photocarcinogenicity of the natural retinoids including retinol, retinal, retinoid acid (RA), retinyl acetate, and RP.