In order to maximize results and minimize complications in the
treatment of acne vulgaris, it is imperative to first decide which
treatment is best for the individual sufferer and also the exact
treatment method to be followed.
Different Groups of Retinoids
Among the many methods and medicines widely available, topical
retinoid preparations are best used for treating mild forms of
non inflammatory acne characterized by the presence of comedones.
Topical retinoids can also be used together with systemic drugs
to treat moderate to severe forms of acne as well.
Retinoids are derived from Vitamin A. They were first observed
to be extremely effective in curing acne in the 1970’s.
There are at present 3 generations of retinoids classified into
nonaromatics, including retinol, tretinoin and isotretinoin; monoaromatic
retinoids and polyaromatic retinoids, which include arotinoid,
adapalene and tazatorene. These third generation retinoids have
anti inflammatory efficacy. Topical retinoids popularly used in
effectively treating acne are tretinoin, isotretinoin, adapalane,
tazarotene and retinaldehyde.
The Function of Topical Retinoids
The aim of acne therapy is to decrease and minimize the incidence
as well as the severity of the basic clinical lesion known as
the microcomedo. If left untreated, a microcomedo may progress
to other severe forms of acne. Retinoids have the capacity to
bind, as well as activate, retinoid receptors on cells. By exerting
their influence on cells via these receptors, retinoids help eliminate
the formation of comedones by normalizing the cell differentiation
in the follicles of the epithelial layer. Retinoids are considered
to be both vitamins as well as hormones due to their binding as
well as activation properties. The topical retinoid treatment
should not only be restricted to application on visible lesions,
but the entire acne prone area should be targeted to help prevent
Tretinoin is the generic name for retinoic acid and is a first
generation nonaromatic topical retinoid also known as Vitamin
A acid. Tretinoin has a high affinity in binding all nuclear hormone
retinoic acid receptors and cellular retinoic acid binding receptors.
Tretinoin is available in cream, gel and solution forms. It is
effective in increasing the formation of follicular epithelial
cells and facilitating the elimination of corneocytes thus enabling
normalization of keratinization and drainage of comedones as well
as preventing the formation of new comedones. The follicles become
clear and aerobic and more within the reach of antimicrobial agents.
This function inhibits the P. acnes bacteria proliferation and
their proinflammatory activity on the follicles.
The patients should be told of the epidermal irritation and pustular
flare side effects, plus the delayed and erratic improvement that
may occur after application. Also, tretinoin usage may cause photosensitization.
Night time application starting with a lower potency is advised.
Patients with sensitive skin should avoid tretinoin and instead
use another retinoid which causes less discomfort. However, nowadays
two new formulations of tretinoin, namely the polyolpolymer-2
and the microsponge delivery system, are used for lower accompanying
This is a first generation retinoid which also has the capacity
to bind CBRAR and RAR receptors. It has comedolytic properties
thereby changing the turnover of epithelial cells in hair follicles.
Topical isotretinoin is available in gel formula with .05 % potency.
Oral isotretinoin is a sebum suppressor but the gel form does
not have this quality. Its effect in reducing both comedolytic
as well as inflammatory acne is almost equal to tretinoin. However,
the adverse irritation effects which occur with tretinoin do not
occur so frequently and as intensely with isotretinoin.
This is a third generation polyaromatic retinoid. Adapalene has
some of the characreristics of tretinoin but it is different physiolochemically.
It normalizes cellular keratinization and inflammation, thus it
is extremely comedolytic as well as anti inflammatory. Though
as effective as tretinoin, it is much better tolerated and produces
less skin irritation and erythema. Also Adapalene is stable with
oxygen and light so it can be applied at any time of the day and
it can be combined with benzoyl proxide. There is negligible absorption
of adapalene and once it goes into the corneum strata, it becomes
enclosed in the targeted area of the epidermis and hail follicle.
Adalapene has enormous potential as a topical therapy in acne.
It has been seen that tazarotene when applied once a day has
greater success in treating non inflammatory acne and reducing
its severity compared to tretinoin. Also tazarotene gel .05% is
more effective in lessening the number of open comedones and papules
and reducing pustules faster than the same potency of tretinoin
gel. However, it is as equally intolerable as tretinoin. Moderate
skin irritation accompanied by burning and itching sensations,
erythema, peeling and dryness is felt by some patients. So it
is advised that tazarotene be applied for a very short period
of time of 30 seconds to 5 minutes everyday for optimum results,
but with a lower irritation level.
This topical retinoid with .05% potency has an effect similar
to that of tretinoin .025%. It has a comedolytic effect and directly
prevents the proliferation of P.acnes. Retinaldehyde has much
better tolerability and can be a better option compared to other