Abstract
Although used widely in cosmetic formulations, topical delivery of niacinamide (LogP = −0.35) is unfavorable by conventional means. Poly(lactide-co-glycolide) (PLGA) formulations, can undergo a sol-gel transition triggered by solvent exchange, entrapping molecules and sustaining their release. The current study aims to exploit the ability of PLGA to gel in situ and enhance the topical delivery of niacinamide in microporated skin. In vitro drug permeation studies were performed using vertical Franz diffusion cells. Microporation was performed using Dr. PenTM Ultima A6, where pre-treatment with a 1 mm needle-length for 10 s and a 0.5 mm needle-length for 5 s, both at 13,000 insertions/min were compared. The effect of different grades of PLGA, EXPANSORB® DLG 50-2A (“low” molecular weight), and EXPANSORB® DLG 50-8A (“high” molecular weight) on topical delivery was also determined. Formulations containing PLGA resulted in successful gelation in situ on application over microporated skin. A significantly higher amount of drug was found in the skin with the 0.5 mm treatment for 5 s (892 ± 36 µg/cm2) than with 1 mm for 10 s (167 ± 16 µg/cm2). Hence, the different grades of PLGA were evaluated with 0.5 mm, 5 s treatment, and a significantly larger amount was seen in skin with the higher rather than the lower molecular weight polymer (172 ± 53 µg/cm2).
Highlights
Niacinamide, known as nicotinamide, the amide form of vitamin B3, is an active ingredient in several dermatological and cosmetic formulations, ranging in concentration from 2% to 5% [1,2]
Being a coenzyme that regulates the formation of two important biochemical cofactors, nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), niacinamide mediates hydrogen transfer in cells, helps them proliferate, and repairs cell damage by neutralizing and absorbing free radicals
The aim of this study was to develop a novel approach to enhance the topical delivery of a hydrophilic active, niacinamide, by forming an in situ gel within microchannels created in skin
Summary
Niacinamide, known as nicotinamide, the amide form of vitamin B3 (niacin), is an active ingredient in several dermatological and cosmetic formulations, ranging in concentration from 2% to 5% [1,2]. Niacinamide increases protein synthesis and the production of ceramide and fatty acids within the skin This results in the stabilization of epidermal barrier function, reduction in transepidermal water loss, and an increase in the moisture content in skin [6,7,8]. A combination of these effects contributes to smoother texture and appearance in aging skin, reduction of fine lines and wrinkles, and prevention of skin dehydration and sagging. This makes niacinamide the active ingredient of choice in more than 600 dermatological products [3,9,10,11], ranging across 45 different categories, including shampoos, skin moisturizers, and cleansing formulations
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