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Int J Pharm. 2014 Apr 10;464(1-2):145-51. doi: 10.1016/j.ijpharm.2014.01.012. Epub 2014 Jan 18.

The effects of heat on skin barrier function and in vivo dermal absorption.

Author information

1
Department of Pharmaceutics, UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom.
2
New Technology R&D, Amway Corporation, 7575 Fulton Street East, Ada, MI 49355, USA.
3
Department of Pharmaceutics, UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom. Electronic address: majella.lane@btinternet.com.

Abstract

Enhanced delivery of ingredients across the stratum corneum (SC) is of great interest for improving the efficacy of topically applied formulations. Various methods for improving dermal penetration have been reported including galvanic devices and micro-needles. From a safety perspective it is important that such approaches do not compromise SC barrier function. This study investigates the influence of topically applied heat in vivo on the dermal uptake and penetration of a model active, allantoin from gel and lotion formulations. A custom designed device was used to deliver 42°C for 30s daily to human subjects after application of two formulations containing allantoin. The results were compared with sites treated with formulations containing no active and no heat, and a control site. In addition to penetration of allantoin, the integrity of the SC was monitored using trans-epidermal water loss (TEWL) measurements. The results showed that just 30s of 42°C topically applied heat was enough to cause significantly more penetration of allantoin from the lotion formulation compared with no application of heat. TEWL data indicated that the integrity of the skin was not compromised by the treatment. However, the application of heat did not promote enhanced penetration of the active from the gel formulation. Vehicle composition is therefore an important factor when considering thermal enhancement strategies for targeting actives to the skin.

KEYWORDS:

Allantoin; Barrier properties; Heat; In vivo; Skin absorption

PMID:
24445121
DOI:
10.1016/j.ijpharm.2014.01.012
[Indexed for MEDLINE]

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