Journal of Adolescent Health 43 (2008) 421– 424
A Review of Adapalene in the Treatment of Acne Vulgaris
Cynthia E. Irby, B.A.a, Brad A. Yentzer, M.D.a, and Steven R. Feldman, M.D., Ph.D.a,b,c,*
aDepartment of Dermatology, Center for Dermatology Research, Wake Forest University School of Medicine; Winston-Salem, North CarolinabDepartment of Public Health Sciences, Center for Dermatology Research, Wake Forest University School of Medicine; Winston-Salem, North CarolinacDepartment of Pathology, Center for Dermatology Research, Wake Forest University School of Medicine; Winston-Salem, North Carolina
Manuscript received January 7, 2008; manuscript accepted June 9, 2008
Abstract
Topical retinoids help address the early lesions of acne vulgaris. Consensus guidelines advocate theuse of topical retinoids as the primary treatment for most forms of acne vulgaris. However, alltopical retinoid preparations may be irritating, and this may contribute to underutilization in clinicalpractices. Topical adapalene fosters topical retinoid treatment of acne with less irritation. Adapaleneis a more stable molecule than tretinoin. Adapalene can be used without concern for photo-deactivation. Because of its chemical stability, adapalene can be used in combination with benzoylperoxide products. The availability of a stable topical retinoid associated with little irritation mayfacilitate meeting acne treatment consensus guidelines. 2008 Society for Adolescent Medicine. All rights reserved.
Topical retinoids; Tretinoin; Comedolytic; Anti-inflammatory; Pediatricians
The pathophysiology of acne involves four key mecha-
palene is a third generation retinoid with minimal side
nisms of action: abnormal proliferation and differentiation of
effects. Adapalene has become widely used because of its
keratinocytes, increased sebum production, hyperproliferation
comparable efficacy and favorable tolerability profile when
of Propionibacterium acnes, and an inflammatory response
initiated by bacterial antigens and cytokines. Topical retinoidstarget the abnormal proliferation and differentiation of keratin-
Adapalene for Treatment of Acne Vulgaris
ocytes and also have anti-inflammatory effects. In addition,topical retinoids enhance penetration of other agents, such as
topical antibiotics, resulting in synergistic effects
Retinoids used for acne therapy include tretinoin, tazaro-
Adapalene is available in two formulations: gel (.1%,
tene, adapalene, and isotretinoin (systemic). Topical retin-
.3%) and cream (.1%). After washing with a gentle cleanser,
oids are comedolytic and are successful at inhibiting the
a thin layer should be applied once daily in the evening to
formation of micro-comedones, the precursor to all acne
the entire face and any other affected area approved by the
lesions. The first-generation retinoids (retinol, tretinoin, and
physician Special care should be taken to avoid the
isotretinoin) are irritating, and may limit compliance. Ada-
eyes, lips, mucous membranes, and other sensitive areas As retinoids may increase photosensitivity, patients shouldbe instructed to minimize sun exposure and to apply a
Potential conflicts of interest: Dr. Feldman has received research,
noncomedogenic sunscreen every morning. The safety and
speaking and/or consulting support from several manufacturers of topical
efficacy in children Ͻ12 years of age have not been deter-
retinoids including Galderma, OrthoNeutrogena, and Stiefel. The Centerfor Dermatology Research is supported by an educational grant from
mined Adapalene is pregnancy category C and should
Galderma Laboratories, L.P. Dr. Yentzer and Ms. Irby have no conflicts to
be used with caution in pregnant women.
*Address correspondence to: Steven R. Feldman, M.D., Ph.D., Depart-
Description and clinical pharmacology
ment of Dermatology, Wake Forest University School of Medicine, Med-
Adapalene’s chemical structure is more stable to light
ical Center Boulevard, Winston-Salem, NC 27157-1071.
and oxidation compared with tretinoin. In an in vitro
1054-139X/08/$ – see front matter 2008 Society for Adolescent Medicine. All rights reserved. doi:10.1016/j.jadohealth.2008.06.005
C.E. Irby et al. / Journal of Adolescent Health 43 (2008) 421– 424
study of adapalene and tretinoin, 95% of tretinoin was
Another 12-week study compared adapalene .1% gel to
degraded within 24 hours in the presence of sunlight and
tretinoin .1% microsphere. At week 4, a greater reduction in
benzoyl peroxide, whereas adapalene had essentially no
non-inflammatory lesions was observed for the tretinoin
degradation under these conditions, even at 72 hours
.1% microsphere; however the tretinoin group also had a
Unlike generic tretinoin gel, adapalene is formu-
greater incidence of skin irritation. Both products had sim-
lated in an aqueous gel, which may account for some of
ilar efficacies (33% vs. 35% mean total lesion reduction) by
the improved tolerability. However, adapalene is also
better tolerated than other formulations of tretinoin
A new formulation of adapalene in a .3% gel is now
available and is even more effective than its .1% predeces-
A proposed mechanism for adapalene’s greater tolerabil-
sor. Compared with adapalene .1% gel, adapalene .3% gel
ity is its selective binding affinity. Unlike tretinoin, ada-
showed greater median percent reduction in total lesion
palene does not bind to the cytosolic retinoic acid binding
(56% vs. 48%; p ϭ .020) and inflammatory lesion counts
proteins but instead selectively binds to the nuclear retinoic
(63% vs. 58%; p ϭ .015) Both concentration per-
acid receptor (RAR) subtypes  and ␥ This selective
formed significantly better than gel vehicle (p Ͻ .001).
binding affinity may play a role in adapalene’s greater
Currently, there are no head-to-head efficacy comparisons
inhibition of keratinocyte differentiation than tretinoin,
of adapalene .3% gel to tretinoin gel, cream, or microsphere.
which was demonstrated in a study using keratinocyte trans-glutaminase expression as a marker This inhibition of
The value of adapalene for maintenance therapy was
keratinocyte differentiation and proliferation is responsible
established in a multicenter, randomized, investigator-
for adapalene’s comedolytic effect. In an in vivo study,
blinded study with a total of 253 subjects. The subjects were
adapalene’s ability to reduce comedone formation was dem-
successfully treated (at least 50% improvement from base-
onstrated by a 50 – 60% reduction in comedone counts com-
line) in a previous 12-week study, and were randomized to
receive adapalene .1% gel or gel vehicle once daily for 16
Another important factor in acne pathogenesis is the
weeks. Adapalene maintenance therapy resulted in higher
inflammation that occurs after microcomedone formation.
rates of maintaining at least 50% improvement (75% vs.
Adapalene inhibits the inflammatory response to micro-
54%; p Ͻ .001) and significantly lower lesion counts com-
comedone formation and bacterial antigens Ada-
palene’s anti-inflammatory effects result from inhibition of
Because of the chemical stability of adapalene, it is well
neutrophil chemotaxis and the lipoxygenase pathyway, both
suited for use in combination with other topicals such as
of which are associated with cutaneous inflammatory reac-
benzoyl peroxide or antibiotics. The effectiveness of ada-
tions Adapalene is more effective at inhibiting neu-
palene in combination therapy for the treatment of mild to
trophil lipoxygenase than is tretinoin Adapalene also
severe acne vulgaris was determined in several studies. In a
has other unique anti-inflammatory mechanisms that may
multicenter, randomized, investigator-blinded study with a
total of 249 subjects, the efficacy and tolerability of thecombination of adapalene .1% gel and topical clindamycin.1% lotion was compared with topical clindamycin .1%
Clinical Studies of Adapalene
lotion and gel vehicle for the treatment of mild to moderate
acne. The subjects applied adapalene or vehicle gel oncedaily in the evening, and topical clindamycin twice daily for
Adapalene is an effective acne treatment. A multicenter,
12 weeks. The combination of adapalene and topical clin-
randomized, investigator-blinded study with 297 enrolled
damycin was more effective than topical clindamycin alone
patients compared the efficacy of adapalene .1% solution to
in reducing the total lesions (46.7% vs. 25.5%, p Ͻ .001),
that of tretinoin .025% gel in a once-daily dosage regimen
inflammatory lesions (55.0% vs. 44.2%, p ϭ .004), and
for 12 weeks. Both agents provided significant mean im-provements in inflammatory lesions (47% and 50%, respec-
non-inflammatory lesions (42.5% vs. 16.3%, p Ͻ .001)
tively), and noninflammatory lesions (57% and 54%)
In another multicenter, randomized, investigator-
In another multicenter, randomized, investigator-blinded
blinded study, 467 patients with severe acne were random-
study, 105 patients with mild to moderate acne vulgaris
ized to receive either the combination of adapalene .1% gel
were treated with adapalene .1% gel versus tretinoin .025%
and oral doxycycline or gel vehicle and oral doxycycline for
gel for 3 months. Adapalene gel was found to be more
a duration of 12 weeks. Compared with oral doxycyline
efficacious than tretinoin gel after 1 week of treatment, with
alone, the combination of adapelene and oral doxycycline
respect to a decrease in inflammatory lesions (32% and
resulted in a larger reduction in median percent change of
17%, respectively, p ϭ .001) and total lesion counts (28%
total lesions (61% vs. 45%, p Ͻ .001), inflammatory lesions
and 22%, p ϭ .042); however there was no statistically
(65% vs. 59%, p ϭ .02), and non-inflammatory lesions
C.E. Irby et al. / Journal of Adolescent Health 43 (2008) 421– 424
week 12 measured on a four-point scale of erythema, peel-ing/scaling, dryness, and stinging/burning were low, rang-
In two controlled, randomized, investigator-blinded, in-
traindividual comparison studies, the tolerance of adapalene.1% gel was compared with six different tretinoin formula-tions (tretinoin .025%, .05%, and .1% cream; tretinoin .01%
Discussion
and .025% gel; and tretinoin .1% gel microsphere) andcontrol (petrolatum). In these studies, adapalene, tretinoin
The development of topical retinoids has proved to be
formulations, and petrolatum were applied to the back daily
essential in the management of acne. As such, our review of
followed by occlusion 5 days per week for 3 weeks to
adapalene is important from a therapeutic perspective be-
evaluate the cumulative irritation potential. The evaluation
cause topical retinoids are underutilized in practice
of irritancy was based on an eight-point scale accounting for
The most compelling predictor of the use or nonuse of
dryness, erythema, papular or papulovesicular responses,
topical retinoids was physician specialty, with nonderma-
edema, and erosions or crusting. Adapalene was signifi-
tologists significantly less likely to use topical retinoids than
cantly better tolerated than all formulations of tretinoin
dermatologists (39.4% vs. 23%) More recent data
(including tretinoin microsphere), and was not statistically
suggest that there is an even broader disparity in use of
different from the control, petrolatum gel (no p value re-
topical retinoids between dermatologists and pediatricians.
In one multicenter, randomized, investigator-blinded
Physicians may be reluctant to prescribe topical retinoids
study, 105 patients with mild to moderate acne vulgaris
because of the irritating side effects of the earlier retinoids,
were treated with adapalene .1% gel versus tretinoin .025%
resulting in poor adherence to treatments and complaints
gel for 3 months to compare the onset of action, tolerability,
about the treatment regimen. Acne treatment regimens may
and impact on quality of life. Adapalene was significantly
also be complicated by the need to use some retinoids at
better tolerated (p Ͻ .05) than tretinoin when evaluated on
different times than benzoyl peroxide or sun exposure. Ada-
a four-point scale for dryness, erythema, immediate and
palene, however, can be used in conjunction with benzoyl
persistent burning, and pruritus. Using the DLQI, there was
peroxide and sun exposure, with less risk of irritation.
a statistically significant improvement in quality of life for
In 2003, an international committee of physicians and
both treatment groups (p Ͻ .05). At weeks 1 and 12, there
researchers developed the most recent set of guidelines for
were improvements in quality of life in favor of adapalene
acne management These largely evidence-based rec-
for items related to problems with close contacts, skin
ommendations advocate targeting as many processes in the
pathogenesis of acne vulgaris as possible. The consensus
The effectiveness and safety of adapalene gel .1% when
guidelines state that a topical retinoid should be used as the
used with other acne treatments was evaluated in a prospec-
primary treatment for mild to moderate acne (including
tive, open-label, multicenter, observational, phase 4 study.
inflammatory acne), secondary to its anti-inflammatory
Adverse events and tolerability of adapalene gel .1% were
properties and its inhibition of the formation of the micro-
evaluated in 1864 subjects. Subjects naïve to acne treatment
comedone, the precursor to all acne lesions. Therefore top-
(n ϭ 1396) received initial combination therapy with ada-
ical retinoids target two key mechanisms in the pathogene-
palene gel, whereas subjects already on nonretinoid therapy
sis of acne. To target three pathogenic factors, it is
(n ϭ 468) added adapalene to their existing regimen. The
recommended that antimicrobial agents be in used in com-
overall rates of moderate to severe cutaneous irritation at
bination with topical retinoids when inflammatory lesions
Oral antibiotic ϩ topical retinoid ϩ BPOa
BPO ϭ benzoyl peroxide; AB ϭ topical antibiotic. Adapted from Gollnick et al. a For female patients, hormonal therapy (oral contraceptives) may be added. b For refractory cases only. C.E. Irby et al. / Journal of Adolescent Health 43 (2008) 421– 424
are present. Oral antibiotics are the drug of choice for
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