Cumulative irritation potential of adapalene 0.1% cream and gel compared with tazarotene cream 0.05% and 0.1%

Despite the many beneficial effects of dermatologic applications, most of the current treatments for acne cause local irritation. The objective of this study was to compare the ability of the epidermis to tolerate adapalene 0.1% cream and gel and tazarotene cream in concentrations of 0.05% and 0.1%. A total of 30 subjects were enrolled in the study. The test products were applied under occlusive dressings at randomized sites on the upper back for approximately 24 hours, 4 times a week, and for 72 hours, once a week, for a period of 3 weeks. Skin reactions (erythema score plus other local reactions) at the product application sites were assessed 15 to 30 minutes after dressing removal. Twenty-six subjects completed the study. A total of 16 subjects discontinued use of 1 or more of the test products because of irritation scores reaching severe or greater; all but one of these discontinuations were at sites treated with the tazarotene products. The mean 21-day cumulative irritancy indices for adapalene 0.1% cream and gel were significantly lower (P=.05) than those for tazarotene cream 0.05% and 0.1% and not notably higher than that of the negative control product.     

Cumulative irritancy potential of adapalene cream 0.1% compared with adapalene gel 0.1% and several tretinoin formulations

Thirty-one subjects (8 males and 23 females; mean age, 49.8 years) were enrolled in a single-center study to assess the irritancy potential of adapalene (Differin cream 0.1% and Differin gel 0.1%) and tretinoin (Avita cream 0.025%, Retin-A cream 0.025%, Retin-A cream 0.05%, Retin-A Micro gel 0.1%, and generic cream 0.025%) as compared with white petrolatum when applied under occlusive conditions. All test materials were applied randomly under occlusion to sites located on the upper area of the subject's back under protective patches. All patches were applied to the same sites unless the degree of reaction to a test product or the adhesive necessitated removal (grade 3). Each test material was applied daily, Monday through Friday, for approximately 24 hours, with the Friday patches left in place over the weekend. Twenty-six of the 31 subjects (84%) completed the study. No subject discontinued because of an adverse event. Five subjects voluntarily discontinued the study early for reasons unrelated to study treatment (4 subject request and 1 lost to follow-up). In the statistical comparison of the 7 test products, the mean cumulative irritancy index of both adapalene cream 0.1% and gel 0.1% was statistically significantly (P<.05) lower than for all of the tretinoin products used and was not significantly higher than the negative control product (white petrolatum).     

A comparative evaluation of tretinoin gel microsphere, 0.1%, versus tretinoin cream, 0.025%, in reducing facial shine

Tretinoin gel microsphere, 0.1%, is a highly effective anti-acne medication formulated with sponge-like microspheres encapsulating the active ingredient, tretinoin. In addition to minimizing cutaneous irritation, this system may also reduce facial shine. This single-center, double-blind, half-face study evaluated the potential of tretinoin gel microsphere, 0.1%, to reduce the appearance of facial shine compared to tretinoin cream, 0.025%. Thirty-five subjects (ages 12 to 24 years) with moderate acne vulgaris and moderate facial oiliness, were evaluated after 4 consecutive days of product use. On sides treated with tretinoin gel microsphere, 0.1%, investigators found significantly reduced facial shine at 3 and 6 hours posttreatment. Subjects' self-evaluations revealed a significant reduction in facial shine at 3 hours posttreatment. Photographic analyses showed reductions in facial shine for both treatments, but decreases were greater on tretinoin gel microsphere, 0.1%-treated sides. Both therapies were well tolerated, and no adverse events occurred. Tretinoin gel microsphere, 0.1%, has the added benefit of reducing the appearance of facial shine, which is a frequent concern in acne patients.     

Comparative tolerance of adapalene 0·1% gel and six different tretinoin formulations

Adapalene 0·1% gel (Differin® gel) is a recently introduced topical treatment for mild to moderate acne which has been demonstrated to be much better tolerated and at least as effective as tretinoin 0·025% gel. We compared the tolerance of adapalene 0·1% gel with six different formulations and concentrations of tretinoin. A total of 55 healthy human subjects were enrolled in two controlled, randomized, observer blinded, intraindividual comparison studies. In the first study, adapalene 0·1% gel was evaluated for its 21-day cumulative irritation potential compared with tretinoin 0·025%, 0·05% and 0·1% cream, tretinoin 0·01% and 0·025% gel, and petrolatum (control). In the second study, adapalene 0·1% gel was evaluated for its 21-day cumulative irritation potential compared with tretinoin 0·025%, 0·05% and 0·1% cream, tretinoin 0·1% gel microsphere, and petrolatum (control). In both studies, cumulative irritation scores helped to define three groups of common irritancy potential, with significant differences between each group. In study A, the three groups were in descending order of irritancy: tretinoin 0·1% cream and tretinoin 0·05% cream; tretinoin 0·025% gel, tretinoin 0·01% gel and tretinoin 0·025% cream; adapalene 0·1% gel and petrolatum (control). In study B, the three groups were in descending order of irritancy: tretinoin 0·1% cream; tretinoin 0·05% cream, tretinoin 0·025% cream and tretinoin 0·1% gel microsphere; adapalene 0·1% gel and petrolatum (control). The experimental results show that adapalene 0·1% gel is significantly better tolerated than any of six formulations of tretinoin, including two gels, three creams and a microsphere formulation, ranging in potency from 0·01% to 0·1%.     

Randomised,controlled trial of the efficacy and safety of adapalene gel 0.1% and tretinoin cream 0.05% in patients with acne vulgaris

BACKGROUND: Previous clinical trials have shown that adapalene gel produces less irritation than tretinoin gels and tretinoin 0.025% cream. Short term results have shown that adapalene is less irritating than tretinoin gels and creams. This study is the first to compare the 0.1% formulation of adapalene gel with the 0.05% strength of tretinoin cream in a formal clinical trial. OBJECTIVE: To investigate the efficacy and tolerability of adapalene gel 0.1% compared with tretinoin cream 0.05% in patients with mild-to-moderate acne vulgaris. METHODS: Ten-week, multicentre, randomised, investigator-masked, active-controlled, parallel group study in 409 patients with acne vulgaris. RESULTS: Adapalene gel 0.1% demonstrated equivalent efficacy in reduction of acne lesion counts and global improvement of acne severity over 10 weeks' treatment and was significantly better tolerated than tretinoin cream 0.05% in terms of erythema, dryness, desquamation and stinging/burning. CONCLUSION: Adapalene gel 0.1% showed equivalent efficacy and was significantly better tolerated than tretinoin cream 0.05% in patients with mild-to-moderate acne vulgaris.     

Cumulative irritation comparison of adapalene gel and solution with 2 tazarotene gels and 3 tretinoin formulations

Forty-two subjects with normal skin were enrolled in a single-center study to assess the cumulative irritancy potential of adapalene (Differin gel 0.1% and Differin solution 0.1%) compared with tazarotene (Tazorac gels 0.05% and 0.1%), tretinoin (Retin-A Micro gel 0.1%, Avita cream 0.025%, and Avita gel 0.025%), and white petrolatum (negative control). All test materials were applied randomly, under occlusion, to sites located on either side of the midline--the mid thoracic area of the subjects' backs. All patches were applied daily, Monday through Friday, to the same sites, unless the degree of reaction to a test product or adhesive necessitated removal (grade 3). Thirty-eight of the 42 subjects (90.5%) completed the study. Thirty-four of those 38 subjects (89.5%) had to discontinue using both tazarotene concentrations due to intolerance. Patch discontinuations for the remaining test materials were as follows: 7 subjects discontinued use of tretinoin microsphere gel 0.1%, 3 discontinued tretinoin cream 0.025%, 1 discontinued tretinoin gel 0.025%, and 1 discontinued adapalene gel 0.1%. None of the subjects discontinued use of the white petrolatum or the adapalene solution 0.1%. Adapalene gel and solution 0.1% were statistically (P<.01) less irritating than both tazarotene gels 0.1% and 0.05%, tretinoin microsphere gel 0.1%, and tretinoin gel 0.025%, and they were not statistically different from tretinoin gel 0.025%.     

Split-face clinical and bio-instrumental comparison of 0.1% adapalene and 0.05% tretinoin in facial acne.

BACKGROUND: Adapalene and tretinoin are topical compounds active for treating acne. OBJECTIVE: To compare the efficacity and safety of adapalene 0.1% gel and tretinoin 0.05% gel in moderately severe facial acne using clinical and objective biometrological assessments. Such information is currently lacking in the literature. METHODS: The split-face method was used in 25 acne volunteers for a 6-week treatment. In addition to clinical counts of lesions, the amount of comedones was assessed using computer-assisted morphometry of cyanoacrylate follicular biopsies. The erythema index and squamometry values were used to quantitate skin irritation. RESULTS: The tretinoin formulation brought better comedolysis and clinical improvement than the adapalene formulation. Erythema was transiently more pronounced on the tretinoin-treated side. Squamometry yielded no significant difference between both products. CONCLUSION: Tretinoin 0.05% gel exhibits a greater anti-acne efficacy than adapalene 0.1% gel, although with temperate tolerability.     

Anti-inflammatory effects of tretinoin (all-trans-retinoic acid) 0.1% and adapalene 0.1% in rats

In this study, the anti-inflammatory effects of tretinoin (all-trans-retinoic acid) 0.1% cream and adapalene 0.1% gel were compared in rats to determine whether there was a difference between these agents. Thirty-six rats of either sex were divided into six groups (two control groups, and an etodolac, indomethacin, tretinoin and adapalene group) of six animals each. Each group was given different drugs or chemicals. The inhibitory activities of the drugs were determined on carrageenan-induced rat-paw oedema. The inhibition rate (53.48%) in the tretinoin group was found to be higher than adapalene and controls (P < 0.05). Adapalene was found to have an inhibition rate of 10.28%, and when compared with the other groups, was found to have no statistically significant anti-inflammatory activity. We conclude that tretinoin has a higher anti-inflammatory activity than adapalene and thus should be preferred for the treatment of inflammatory lesions.     

Compared efficacy and safety of tretinoin 0.1% microsphere gel alone and in combination with benzoyl peroxide 6% cleanser for the treatment of acne vulgaris

Our purpose was to evaluate the efficacy and safety of a combination of benzoyl peroxide 6% cleanser and tretinoin 0.1% microsphere gel versus monotherapy with tretinoin 0.1% microsphere gel. Eighty-seven healthy males and nonpregnant nonlactating females between the ages of 12 and 30 years with moderate inflammatory acne vulgaris were enrolled in this randomized controlled, investigator-blind, parallel group clinical trial. Subjects were evaluated over 12 weeks for a total of 4 visits. The investigators and subjects completed questionnaires about the test medications. Data from the 56 subjects completing the protocol were considered in the analyses of efficacy and tolerability. The reduction in inflammatory lesions from baseline was significant for both treatment groups at the end of the study. However, there was a significantly greater reduction in the group receiving the combination regimen. Both treatment groups had significant reductions from baseline in noninflammatory lesions at week 12, but no differences were observed between treatment groups. With the exception of skin tightness, which was significantly greater at week 12 in the subjects who received the monotherapy, there were no significant differences between the 2 treatment groups with respect to localized irritation. Adverse events were rare in all subjects. Not only did the combination regimen result in a greater reduction of inflammatory acne lesions than use of the monotherapy but also it did not result in an increase in local irritation.     

0.1%阿达帕林凝胶预防和减轻寻常痤疮复发的多中心随机对照临床试验

目的评价0.1%阿达帕林凝胶维持治疗对于预防和减轻寻常痤疮复发的作用.方法采用多中心、区组随机、开放、对照的方法,共入选患者246例,均为经过阿达帕林和克林霉素(特丽仙)联合治疗或特丽仙单独治疗获得有效(改善≥25%)的寻常痤疮患者,随机分为两组,一组外用0.1%阿达帕林凝胶,另一组不用药,均观察12周.结果239例患者完成治疗和观察,阿达帕林组121例,对照组118例.治疗4周后阿达帕林组炎性皮损数的减少显著优于对照组(P＜0.05),并维持至12周;治疗8周后阿达帕林组皮损总数和非炎性皮损数的减少也显著优于对照组(P＜0.01),并维持至12周.治疗结束后,阿达帕林组总体改善率为66.9%,对照组为4.2%(P＜0.01);阿达帕林组总复发率为4.1%,对照组为83.9%;两组间差异有显著性(P＜0.01).阿达帕林组有个别病例有轻度局部刺激反应,两组间不良反应差异无显著性(P＜0.05).结论阿达帕林凝胶可有效地治疗寻常痤疮,并维持治疗效果,且不增加局部刺激反应,对于减少病情复发具有显著效果.     

Topical retinoids in acne – an evidence‐based overview

Topical retinoids are important tools in the management of acne because they act against comedones and microcomedones and have direct anti‐inflammatory effects. The substances approved for acne treatment comprise tretinoin (all‐trans‐retinoic acid),isotretinoin (13‐cis retinoic acid) as well as the synthetic third‐generation polyaromatic retinoids adapalene and tazarotene,the latter being approved for acne treatment in the US only.Retinaldehyde is used in cosmetic preparations against acne. All topical retinoids are effective as single agents in mild to moderate acne but differ in efficacy and tolerability. Tazarotene 0.1% is more effective than tretinoin 0.025% or 0.1% microsphere gel or adapalene 0.1% gel or cream (EBM‐level 2c). Adapalene 0.1% is equally effective to tretinoin 0.025% or tretinoin microsphere 0.1% gel or tretinoin 0.05% cream or isotretinoin 0.05% gel (EBM‐level 2c). Adapalene 0.1% gel is significantly better tolerated than tazarotene 0.1% gel, tretinoin 0.025% and tretinoin 0.05% gel, tretinoin 0.05% cream,tretinoin microsphere 0.1% gel or isotretinoin 0.05% gel (EBM‐level 2c).The safety profile of topical retinoids differs from their systemic counterparts and is related mainly to local adverse effects, such as erythema, dry‐ness,itching and stinging.The currently available evidence justifies the use of topical retinoids in most types of acne and during maintenance treatment.     

Adapalene 0·1% gel for the treatment of acne vulgaris: its superiority compared to tretinoin 0·025% cream in skin tolerance and patient preference

One hundred patients with acne vulgaris applied adapalene (Differin®) 0·1% gel to one side of their face and tretinoin 0·025% cream to the other once a day for 4 weeks; the side of application was determined by randomization code. Patient tolerance (assessed as the side of the face least irritated by drug application) was recorded weekly and patient preference (assessed as the preparation more easily spread, absorbed more quickly, smelled better, felt best on the skin and least greasy to the feel) at completion of the study. The investigator measured skin irritation weekly, scoring erythema, skin dryness, desquamation and burning/stinging on a 10-point scale.
  After each week of treatment, 64–68% of patients found adapalene 0·1% gel more tolerable than tretinoin 0·025% cream ( P < 0·05). At study completion, 65% of patients preferred adapalene 0·1% gel over tretinoin 0·025% cream ( P  = 0·003). An overall assessment showed adapalene 0·1% gel was significantly less irritating to the skin in terms of producing erythema, dryness, desquamation and burning/stinging, at Visits 2, 3 and 4 ( P < 0·02).
  Thirty-two patients experienced mild to moderately severe adverse events; three had adverse events considered to be drug related (two with skin discomfort; one with skin dryness). One patient stopped using the study drugs because of dry skin.
  This study showed that a majority of patients preferred adapalene 0·1% gel over tretinoin 0·025% cream and that it caused significantly less skin irritation.     

The stability of tretinoin in tretinoin gel microsphere 0.1%

Topical tretinoin is highly effective and widely used in the treatment of acne vulgaris. In studies to determine the degree of tretinoin photo degradation (isomerization), 2 tretinoin formulations, tretinoin gel microsphere 0.1% and tretinoin gel 0.025%, alone or in combination with erythromycin-benzoyl peroxide topical gel, were exposed to fluorescent light, incandescent light, or darkness for up to 24 hours. Results of the investigations revealed that after 24 hours of exposure to fluorescent light, 98% of the initial tretinoin in the tretinoin gel microsphere 0.1% formulation remained unchanged. When tretinoin gel microsphere 0.1% was combined with erythromycin-benzoyl peroxide topical gel and exposed to fluorescent light, 99% and 87% of the tretinoin was recovered after 4 and 24 hours, respectively, indicating only a limited amount of degradation. In contrast, exposure of tretinoin gel 0.025% to 24 hours of fluorescent light resulted in up to 69% tretinoin degradation and up to 89% degradation when the gel was combined with the erythromycin-benzoyl peroxide topical gel. The data suggest that the tretinoin gel microsphere 0.1% formulation offers marked protection against tretinoin photo degradation, even in the presence of a strong oxidizing agent such as benzoyl peroxide.     

Adapalene 0·1% gel and adapalene 0·1% cream stimulate retinoic acid receptor mediated gene transcription without significant irritative effects in the skin of healthy human volunteers

A randomized, investigator masked, intra individual comparative study was conducted in 30 healthy volunteers to compare the cutaneous effects of adapalene 0·1% gel and adapalene 0·1% cream with their respective vehicles, using tretinoin 0·05% cream ( n  = 21) or tretinoin 0·1% cream ( n  = 9) and a tretinoin cream vehicle ( n  = 30) as controls. The products were applied to hip/buttock skin for 4 days under occlusive conditions. Cytosolic retinoic acid binding protein-II (CRABP-II) mRNA levels were measured using the RT-PCR technique in punch biopsies taken from 10 subjects. Epidermal thickness was assessed using image analysis of haematoxylin and eosin stained sections from another 11 subjects. Erythema was assessed in all subjects both by a visual scoring system and by chromameter.
  Adapalene 0·1% gel and adapalene 0·1% cream produced similar significant increases in CRABP-II mRNA levels compared to their vehicles ( P < 0·01). The two tretinoin formulations also resulted in similar significant increases in CRABP-II compared to the cream vehicle ( P < 0·001). However, only the two tretinoin formulations resulted in an increase in epidermal thickness and only the tretinoin 0·1% cream resulted in significant erythema.
  Adapalene 0·1% gel and adapalene 0·1% cream induce RAR-mediated gene expression to a similar degree in this model, without the irritant effects of tretinoin.     

Use of adapalene in alopecia areata: Efficacy and safety of mometasone furoate 0.1% cream versus combination of mometasone furoate 0.1% cream and adapalene 0.1% gel in alopecia areata

Alopecia areata (AA) is an autoimmune disease characterized by non‐cicatricial hair loss. No definitive therapy currently exists for AA. To compared the efficacy and safety of the mometasone furoate 0.1% cream alone with the mometasone furoate 0.1% cream plus adapalene 0.1% gel in treatment of AA. Twenty patients with AA and with mean age of 27.4 ± 9.2 years were enrolled. Patches with a diameter of < 5 cm were treated with mometasone furate 0.1% cream (M), and patches with a diameter of ≥5 cm were treated with mometasone furate 0.1% cream plus adapalene 0.1% gel (M + D) for a period of 12 weeks. Hair regrowth was evaluated using a Re‐growth score (RGS). Mean RGSs of M + D group were higher than M group for 4th week (2.60 vs. 1.45); 8th week (3.85 vs. 2.40) and 12th week (4.40 vs. 3.30). Mean percentages of hair re‐growth in M + D group were statistically higher than M group for 4th (50.2% vs. 23.5%), 8th (78.5% vs. 50.7%), and 12th week (90.5% vs. 71%). Study revealed the efficacy and safety of adapalene and mometasone furoate combination in AA. Adapalene can be used as a new therapeutic modality in AA.     

Adapalene 0.1% and benzoyl peroxide 2.5% as a fixed-dose combination gel is as well tolerated as the individual components alone in terms of cumulative irritancy

International guidelines recommend the combination of retinoids (e.g. adapalene, tazarotene) and benzoyl peroxide for treating acne because of their complementary mechanisms of action. A new fixed-dose combination gel of adapalene 0.1% and benzoyl peroxide (BPO) 2.5% (adapalene/BPO*) is an effective acne treatment and offers the advantage of a once daily application. This paper reports the results of a cumulative irritancy study in healthy volunteers comparing adapalene/BPO to adapalene 0.1% and BPO 2.5% applied separately, BPO 10% gel, tazarotene 0.1% gel and the gel vehicle as a control.There was no significant difference between the mean cumulative irritation index (MCII) for adapalene/BPO and any test product except tazarotene 0.1% gel, which had a significantly greater MCII than all other test products (p < 0.05). This study showed that adapalene/BPO as a fixed-dose combination is as well tolerated as BPO 2.5% gel alone or adapalene 0.1% gel alone in terms of cumulative irritancy.*Epiduotrade mark, Galderma S.A.     

Pivotal clinical trials of adapalene in the treatment of acne

Adapalene, a naphthoic-acid derivative, possesses some of the biological activities of tretinoin but has distinct physicochemical properties and binding properties for selective affinity for retinoic acid receptors. As such, adapalene is less likely to be associated with certain local tolerability problems (e.g. burning, erythema, pruritus).
Over the past 5 years, numerous clinical trials have been conducted to compare the efficacy and tolerability of adapalene and tretinoin in the treatment of acne vulgaris. Three pivotal, large, well-controlled studies involving almost 900 patients showed that adapalene gel 0.1% and adapalene solution 0.1% are at least as effective as tretinoin gel 0.025%, with superior local tolerability. Adapalene cream 0.1% has proven to be significantly more effective than vehicle, with response rates comparable to those observed with the gel and solution. A meta-analysis of trials with the gel formulation confirmed these findings, showing equivalent efficacy and improved tolerability vs. tretinoin gel 0.025%. Moreover, the onset of clinical effect was shown to be significantly more rapid than that of tretinoin gel. Taken together, these studies demonstrated that adapalene has overall efficacy similar to that of topical tretinoin, but with a superior therapeutic ratio that may result in superior outcomes in clinical practice through improved compliance. This may be expected because of its lesser potential for skin irritation, especially early in treatment, and because of greater convenience in that no waiting period is required between face washing and application of the product. Therefore, 5 years of clinical experience have established that adapalene in its various formulations is a valuable addition to current treatments for acne vulgaris.     

Comparative irritancy study among retinoid creams and gels

BACKGROUND: Topical retinoids, although very useful in dermatology, may be irritating to some patients. OBJECTIVE: There are a number of topical retinoids available in Canada, and the objective of the present study was to evaluate the irritancy potential in humans of retinoid gels and creams presently available in Canada. METHODS: Thirty healthy adults were administered 10 products (five creams, three gels, petrolatum, and sodium lauryl sulfate (SLS) 0.1% w/v) for up to 21 consecutive days. RESULTS: Early termination of patching due to irritation was required for the tretinoin creams and gels and SLS more frequently and earlier in the study than for adapalene and petrolatum (p =.001). Statistically significant, among-group differences were noted in the severity of irritation at each day and for the cumulative score for both the creams and the gels (p =.0001), in favour of adapalene over the tretinoin products. CONCLUSION: By several measures, adapalene cream and gel were less irritating upon multiple dosing than various tretinoin creams and gels.     

Topical adapalene gel 0.1% vs. isotretinoin gel 0.05% in the treatment of acne vulgaris: a randomized open-label clinical trial

BACKGROUND: Topical application of isotretinoin and adapalene has proved effective in treating acne vulgaris. Both drugs demonstrate therapeutic advantages and less irritancy over tretinoin, the most widely used treatment for acne. They both act as retinoid agonists, but differ in their affinity profile for nuclear and cytosolic retinoic acid receptors. OBJECTIVE: To compare the efficacy and tolerability of adapalene gel 0.1% and isotretinoin gel 0.05% in the treatment of acne vulgaris of the face, in a randomized open-label clinical trial. METHODS: Eighty patients were enrolled and were instructed to apply adapalene gel 0.1% or isotretinoin gel 0.05% once daily over a 12-week treatment period. Efficacy determination included noninflammatory and inflammatory lesion counts by the investigator and global evaluation of improvement. Cutaneous tolerance was assessed by determining erythema, scaling and burning with pruritus. RESULTS: Adapalene and isotretinoin gels were highly effective in treating facial acne. Adapalene gel produced greater reductions in noninflammatory and inflammatory lesion counts than did isotretinoin gel, but differences between treatments were not statistically significant. Adapalene gel was significantly better tolerated than isotretinoin gel during the whole treatment period. CONCLUSIONS: The two gels studied demonstrated comparable efficacy. When adapalene and isotretinoin were compared, significantly lower skin irritation was noted with adapalene, indicating that adapalene may begin a new era of treatment with low-irritant retinoids.     

Control of microcomedone formation throughout a maintenance treatment with adapalene gel, 0.1%

BACKGROUND: Microcomedones representing the clinically non-visible central precursor lesions of acne are induced by sebaceous hyperplasia as well as altered follicular growth and differentiation, and evolve into both comedones and inflammatory lesions. Thus, targeting microcomedone formation is essential in the prevention and therapeutic control of acne. OBJECTIVE: The aim of this study was to assess the capacity of adapalene gel, 0.1%, to control the number of microcomedones after a combination treatment followed by a maintenance treatment. METHODS: This was a single-site exploratory study in subjects with a diagnosis of mild to moderate acne vulgaris and the presence of at least 250 microcomedones per cm(2) at screening visit, counted via cyanoacrylate strips (CyASt). During the first 8 weeks, a combination of adapalene gel (0.1%) and benzoyl peroxide gel (2.5%) was applied. During the randomized, investigator-blinded, and vehicle-controlled 12-week maintenance phase, adapalene once daily (QD), or adapalene alternately with its vehicle once daily every other day (QoD), or vehicle QD were applied to the face. CyASt sampling on the forehead was done at baseline, week 8, and week 20. Lesion counting allowing calculating a defined success rate was done at all visits. RESULTS: A total of 54 subjects entered the combination phase, and 49 subjects were randomized into the maintenance phase: 16 in both the adapalene QD and the QoD group and 17 subjects receiving the vehicle. The microcomedone median count decreased for all groups until week 8 (end of combination phase) from 319 to 157. Microcomedone counts at the end of the maintenance phase (week 20) showed a significant percent difference (P = 0.04) between adapalene QoD (-53.5) and the vehicle (-42.1) and between adapalene QD (-50.6) and the vehicle (P = 0.037) compared with baseline. CONCLUSION: The application of adapalene gel, 0.1% monotherapy daily, or alternately every other day, significantly helps to control the microcomedone count during a 12-week maintenance treatment after a previous combination therapy with benzoyl peroxide in patients with mild to moderate acne.