showed acute ICD whilst only 15% of Blacks
presented with this as established by erythema
(redness of the skin) from a 1% dichlorethylsulfide
also known as mustard gas (Modjtahedi and
Maibach, 2002). It was determined that the SC plays
an imperative role in Black skin, even though the
thickness of the SC is the same in both ethnic groups.
However, Black SC has decreased amounts of
ceramides and contains larger amounts of cellular
layers compared to Caucasian skin (Corcuff et al.,
1991), which made black skin less susceptible to ICD.
This could potentially provide ways in which ICD
can be treated or what could be included in topical
formulations for Caucasian individuals suffering from
ICD.
As there are variations on the prevalence of certain
skin disorders, studies have also shown that ethnicity
influences drug permeation to the skin (Vitorino et
al., 2015), one study demonstrated that fluocinolone
acetonide which used to reduce inflammation
and itchiness of the skin had higher permeation in
Caucasian skin compared to Afro-Caribbean skin.
The difference in the results obtained from this
study emphasised the difference in the SC between
both ethnic groups, Afro-Caribbean skin contains a
significant number of keratinocyte layers in the SC
which accounted for the lower permeation.
Keratinocytes have stronger cellular cohesion and
contain elevated lipid content in the SC in Afro-
Caribbean individuals. This also plays a role in
increasing the integrity of the SC (Singh and Morris,
2011). Additionally, methyl nicotinate was used as a
drug model in a study comparing its permeation in
four different ethnic groups. The study showed that
Afro-Caribbean’s had the lowest skin permeation of
methyl nicotinate, followed by Asians, Caucasians,
and finally, Hispanics (Leopold and Maibach,1996).
This, therefore, goes to show the importance of
personalised topical drugs; as seen some studies
have shown that certain drugs permeate some
ethnic groups better than others due to structural
differences in the skin specifically in SC.
Discussion and Conclusion
In conclusion, because the skin is a complex organ it is
important to understand the factors that could hinder
absorption through this route. Therefore, melanin is
the core pigment that brings about the differences
between Caucasian and Black skin, although there are
minor differences; both skin types are, to an extent
very much alike. With regards to skin structure, the
SC is the main structure that provides most of the
diversity between various ethnic skins. It affects an
essential aspect of percutaneous absorption, which
is the permeation of drugs across the skin. This
permeation across the skin is essential as it plays an
important role in ensuring that the drugs absorbed
through this route of administration reach their target
sites and therefore have their maximum effect.
The studies carried on the structure and function
of the skin are mostly dated, this shows that new
studies should be conducted to further expand on
the current knowledge around skin ethnicity. New
research in combination with modern technology
available would enable life-changing discoveries to be
made regarding the different role’s ethnicity plays in
drug absorption. This could provide a paradigm shift
in how we consider personalised medicines in the
context of transdermal delivery.
Therefore, the relevance of this work was to gain an
understanding of the structural differences in the
skin amongst different ethnicities, and how these
differences could potentially affect the uptake of
medicines across the skin. By understanding this, it
could potentially aid in providing topical formulations
that are tailored to each patient needs regardless of
skin type and structure.
References
PulpBits, (2013). Structure of the skin. Available
at:< https://pulpbits.net/7-skin-structure-anatomy-
diagrams/structure-of-skin/ > [Accessed on 24th of
June 2019].
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