Anti-melasma codrug of retinoic acid assists cutaneous absorption with attenuated skin irritation

Laser-assisted nanoparticle delivery to promote skin absorption and penetration depth of retinoic acid with the aim for treating photoaging

Retinoic acid (RA) is an approved treatment for skin photoaging induced by ultraviolet (UVA). Topically applied RA is mainly located in the stratum corneum (SC) with limited diffusion into the deeper strata. A delivery system capable of facilitating dermal delivery and cellular internalization for RA is critical for a successful photoaging therapy. Two delivery approaches, namely nanoparticles and laser ablation, were combined to improve RA's absorption efficacy and safety. The nanoparticle absorption enhancement by the lasers was compared between full-ablative (Er:YAG) and fractional (CO₂) modalities. We fabricated poly-L-lactic acid (PLA) and PLA/poly(lactic-co-glycolic acid) (PLGA) nanoparticles by an emulsion-solvent evaporation technique. The mean size of PLA and PLA/PLGA nanocarriers was 237 and 222 nm, respectively. The RA encapsulation percentage in both nanosystems was > 96 %. PLA and PLA/PLGA nanocarriers promoted RA skin deposition by 5- and 3-fold compared to free control. The ablative lasers further enhanced the skin deposition of RA-loaded nanoparticles, with the full-ablative laser showing greater permeation enhancement than the fractional mode. The skin biodistribution assay evaluated by confocal and fluorescence microscopies demonstrated that the laser-assisted nanoparticle delivery achieved a significant dermis and follicular accumulation. The cell-based study indicated a facile uptake of the nanoparticles into the human dermal fibroblasts. The nanoparticulate RA increased type I collagen and elastin production in the UVA-treated fibroblasts. A reduction of matrix metalloproteinase (MMP)-1 was also highlighted in the photoaging cells. The calculation of therapeutic index (TI) by multiplying collagen/elastin elevation percentage and skin deposition predicted better anti-photoaging performance in Er:YAG laser-assisted nanoparticle delivery than CO₂ laser. Nanoencapsulation of RA decreased the cytotoxicity against skin fibroblasts. In vivo skin tolerance test on a nude mouse showed less skin damage after topical application of the nanoparticles than free RA. Our results hypothesized that the laser-mediated nanoparticle delivery provided an efficient and safe use for treating photoaging.

Nanocrystalline chloroxine possesses broad-spectrum antimicrobial activities and excellent skin tolerability in mice

Background: Antimicrobial submicrometer particles are being studied as promising interventions against a wide range of skin conditions, such as fungal or bacterial infections. Aims: To submicronize chloroxine, the crystalline compound 5,7-dichloro-8-hydroxyquinoline, by nanoprecipitation and characterize the resulting assemblies. Methods: The chloroxine particles were stabilized by a nonionic surfactant and were studied by a broth microdilution assay against 20 medically important bacteria and fungi. The intervention was studied using a murine model of skin irritation. Results & conclusions: Chloroxine nanoparticles with a diameter of 600-800 nm exhibit good tolerability in terms of skin irritation in vivo and good antimicrobial activity. Thus, the fabricated formulation shows great promise for interventions for both cutaneous infection control and prophylaxis.

A Clinical Anti-Ageing Comparative Study of 0.3 and 0.5% Retinol Serums: A Clinically Controlled Trial

BACKGROUND

Retinol influences the process of keratinization of the epidermis, which improves stratum corneum structure and reduces transepidermal water loss. It also significantly enhances mature skin by brightening hyperpigmentation and reducing the signs of photoageing. Cosmeceuticals are intended to both provide aesthetic effects for the skin and allow dermatological treatment. The aim of the study was to assess the rejuvenating effect of retinol serum on facial skin at concentrations of 0.3 and 0.5%, as well as any improvements in skin brightening and elasticity.

MATERIALS AND METHODS

Thirty-seven volunteers were included in the study, after confirming tolerance. The novel formula was applied once daily to the face for a period of 12 weeks: one retinol concentration on the left side and the other on the right. The initial study with liquid crystal formula (study vehicle) was carried out for 8 weeks on 28 volunteers. Treatment efficiency was evaluated at baseline, and 56 and 84 days following treatment using the multi probe adapter and Fotomedicus imaging system. PRIMOS was used to measure skin surface roughness. The visual analogue scale method enabled the results to be determined by 3 independent specialists.

RESULTS

Skin hyperpigmentation, unevenness, and wrinkles gradually decreased over the course of treatment, both on the left and right parts of the face. Adverse events were predominantly mild or moderate skin irritation. More frequent and more intense symptoms were observed on the left side (0.5%).

CONCLUSION

Retinol in liquid crystal formulation is safe and provides significant clinical benefits associated with unification of skin colour, overall skin tone, skin elasticity, and moisture. Regular use of retinol typically results in brightening of the skin and reduced signs of ageing. The objective findings confirmed the effectiveness of the procedures.

Retinoids: active molecules influencing skin structure formation in cosmetic and dermatological treatments

Vitamin A is the first vitamin approved by the Food and Drug Administration as an anti-wrinkle agent that changes appearance of the skin surface and has anti-aging effects. Vitamin A is in a group of fat-soluble substances and belongs to the category of retinoids. Apart from retinol, that group includes structurally related substances with the biological properties of retinol. Since the biological activity of the substances differs, for the purpose of standardization, it is given in retinol equivalents. Vitamin A and its derivatives are among the most effective substances slowing the aging process. Retinoids regulate the cell apoptosis, differentiation and proliferation. Anti-wrinkle properties of retinoids promote keratinocytes proliferation, strengthen the protective function of the epidermis, restrain transepidermal water loss, protect collagen against degradation and inhibit metalloproteinases activity. Retinoid activity is related to high affinity for nuclear receptors: RAR – retinoid acid receptors and RXR – retinoid X receptors.