Analyzing the medical history of the patients to be treated of acne vulgaris
will help the therapist or doctor to decide which treatment will work best
for the patient while simultaneously minimizing any likelihood of complications.
Different Groups of Retinoids
Non-inflammatory acne is characterized by the presence of comedones. The
best method of treatment for this type of acne is the topical retinoid
preparation. Using topical retinoids along with systemic drugs can treat
severe forms of acne.
The effect of retinoids on acne was first observed in the 1970s. The retinoids
were derived from Vitamin A and have 3 known generations as of this writing;
the third generation retinoids are known to have anti-inflammatory properties.
These 3 generations of retinoids are classified into non-aromatic retinoids,
mono-aromatic retinoids, and poly-aromatic retinoids. Non-aromatic retinoids
include retinol, tretinoin, and isotretinoin. Poly-aromatic retinoids include
arotinoid, adapalene, and tazatorene. Among the topical retinoids that
popular in treating acne are trenetoin, isotrenetoin, adapalene, tazarotene,
The Function of Topical Retinoids
Acme therapy is aimed to decrease the incidences and minimize the severity
of the basic clinical lesion known as microcomedo. A microcomedo has the
tendency to grow into full-blown severe cases of acne. When retinoids are
introduced in the system, it binds and activates the retinoid receptor
cells. When retinoids exert their influence on these receptors, it normalizes
the cell differentiation in the follicles of the epithelial layer, thus
eliminates the formation of comedones. Because of this unique binding and
activation properties of retinoids, they are considered as vitamins as
well as hormones. Treating acne with retinoid is not restricted to the
application on the visible lesions but targeting the entire area prone
to acne helps prevent future spots.
Tretinoin is the generic name of the first-generation non-aromatic topical
retinoid Vitamin A acid, which has a high affinity in binding nuclear hormone
retinoic acid receptors and cellular retinoic acid binding receptor.
Tretinoin is available in the market in cream, gel, and solution forms.
Using tretinoin in the treatment prevents the formation of new comedones,
increases the formation of follicular epithelial cells, and initiates the
elimination of corneocytes that enables the normalization of keratinazation
and drainage of comedones. As a result, the follicles became clearer and
more aerobic, allowing the antimicrobial agents to reach them. This inhibits
the proliferation the P. acne bacteria and stops any pro-inflammatory activity
on the follicles.
It is advisable to inform the patient of the epidermal irritation, pustular
flare side effects, and the delayed and erratic improvements that could
occur after application of tretinoin treatment. Application of tretinoin
may cause photosensitization, advising a night-time application starting
with a lower potency of tretinoin. Those patients that have sensitive skins
can consider any other types of retinoid that causes less discomfort. However,
two new formulations of tretinoin – polyolpolymer-2 and microsponge
delivery system are now being used for lower accompanying irritation.
Isotretinoin is a first generation retinoid that has the capacity to bind
CBRAR and RAR receptors and possesses comedolytic properties that change
the turnover of epithelial cells in hair follicles. Topical isotretinoin
is available in gel formula at 0.05% potency but does not suppress sebum
unlike oral isotretinoin. It is almost equal to tretinoin in the reduction
of comedolytic and inflammatory acne, and the adverse irritation effects
that can be experienced when using tretinoin is not as frequently and as
intensely experienced with isotretinoin.
Adapalene is a third-generation poly-aromatic retinoid that exhibits some
characteristics of tretinoin despite their physiolochemical difference.
Adapalene is extremely comedolytic and anti-inflammatory due to its ability
to normalize keratinization and inflammation. Although it is as effective
as tretinoin, topical application of adapalene is much better tolerated
and produces less skin irritation and erythma. There is no risk of photosensitization
when applying adapalene during the daytime as it is stable with oxygen
and light and can be combined with benzoyl peroxide. It also goes directly
to the targeted area once it gets past through the corneum strat, enclosing
itself in the epidermis and hair follicles. This is due to the fact that
the absorption rate of adapalene is negligible. Researchers are currently
looking at the enormous potential of adapalene in acne therapy.
Application of tazarotene once a day showed greater success in treating
non-inflammatory acne and reduction of the acne’s severity compared
to the results on tretinoin. Tarazotene gel 0.05% is more effective than
tretinoin gel with the same potency in lessening the number of open comedones
and papules, and reduces pustules faster. However, the side effects that
come along with it are as intolerable as tretinoin. These side effects
include moderate skin irritation accompanied by burning or itching sensations,
erythema, and peeling and dryness of the skin. Thus, to lower irritation
levels, application of tazarotene for short periods of time (30 seconds
to five minutes) is highly recommended.
0.05% potency of retinaldehyde has similar effects to that of tretinoin
at 0.025% potency. It also has comedolytic effects and directly prevents
the proliferation of P. acne. Retinaldehyde is a better option among retinoids
because it has much better tolerability.