JOURNAL TRANSCRIPT
Original Paper Skin Pharmacol Physiol 2016;29:1–8 DOI: 10.1159/000439439
Received: June 9, 2015 Accepted after revision: August 16, 2015 Published online: October 13, 2015
Reduction of Inflammatory and Noninflammatory Lesions with Topical Tyrothricin 0.1% in the Treatment of Mild to Severe Acne Papulopustulosa: A Randomized Controlled Clinical Trial Claudia Richter a Carina Trojahn a Kathrin Hillmann a Gabor Dobos a Andrea Stroux b Jan Kottner a Ulrike Blume-Peytavi a a Clinical Research Center for Hair and Skin Science, Department of Dermatology and Allergy, and b Department of Biometry and Clinical Epidemiology, Charité – Universitätsmedizin Berlin, Berlin, Germany
Key Words Acne vulgaris · Antimicrobial peptides · Tyrothricin · Lesion count
Abstract Background/Aims: Antibiotic-induced drug resistance requires new approaches in topical acne treatment. Tyrothricin is known to produce no resistance. In this study, it was tested for the first time in topical acne treatment. The efficacy and tolerability of topical tyrothricin 0.1% was evaluated. Methods: A randomized, active comparator-controlled, exploratory, observer-blind clinical study was conducted in 24 patients with acne papulopustulosa. Randomization on a split-face was either tyrothricin versus clindamycin + benzoyl peroxide (BPO) (n = 12) or tyrothricin versus BPO 5% (n = 12). The main outcome was change in inflammatory and noninflammatory lesion counts. Results: The mean differences in inflammatory lesion counts from baseline were –12.3 (95% CI: –20.5 to –4.1) in clindamycin + BPO, –10.2 (95% CI: –15.3 to –5.0) in BPO 5%, and –7.7 (95% CI: –11.7 to –3.7) in tyrothricin. Tyrothricin reduced noninflammatory lesions (mean difference: –6.5 (95% CI: –11.6 to –1.4)
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© 2015 The Author(s) Published by S. Karger AG, Basel 1660–5527/15/0291–0001$39.50/0 This article is licensed under the Creative Commons AttributionNonCommercial-NoDerivatives 4.0 International License (CC BYNC-ND) (http://www.karger.com/Services/OpenAccessLicense). Usage and distribution for commercial purposes as well as any distribution of modified material requires written permission.
and caused less product-related adverse events (n = 31) compared to BPO (n = 37) and clindamycin + BPO (n = 20). Conclusion: The results indicate that tyrothricin might be a candidate for treating acne and it seems to be more tolerable than both comparator treatments. © 2015 The Author(s) Published by S. Karger AG, Basel
Introduction
Acne vulgaris is a disorder of the pilosebaceous unit, mostly affecting teenagers of both genders. The pathogenesis of acne is multifactorial. There are four primary pathogenic factors, which interact to produce acne lesions: (1) increased sebum production in the sebaceous glands, (2) alterations in the keratinization process, (3) Propionibacterium acnes follicular colonization, and (4) release of inflammatory mediators [1–5]. Hyperkeratinization leads to plugging of the follicular duct [5] which results in the clinically invisible microcomedones preceding acne lesion formation. They might develop into noninflammatory lesions (closed and open comedones) and into clinically visible inflamed papules, Claudia Richter Clinical Research Center for Hair and Skin Science Department of Dermatology and Allergy Charité – Universitätsmedizin Berlin, Charitéplatz 1, DE–10117 Berlin (Germany) E-Mail claudia.richter @ charite.de
pustules, and nodules. Despite this differentiation, the inflammatory potential of acne vulgaris is given throughout the course of the disease; hence, acne is an inflammatory disease from its beginning onwards [3, 6–11]. For the treatment of mild to severe papulopustular acne, topical treatments with benzoyl peroxide (BPO), azelaic acid, and retinoids as well as combinations of adapalene/BPO, clindamycin/BPO, and systemic antibiotics/ adapalene are recommended [1]. These established combination products of antibiotic and antimicrobial agents aim at reducing the risk of developing antibiotic resistance and maintaining treatment efficacy in acne patients. Topical BPO has antimicrobial, comedolytic, sebosuppressive, and anti-inflammatory properties and does not form resistances [1, 12]. One major concern in the treatment of acne is the growing rate of resistant cutaneous propionibacteria, especially seen in erythromycin and clindamycin treatments [13]. Searching for alternative treatment options in order to reduce antibiotic-induced resistance as well as developing new effective and tolerable therapies for acne patients have become main targets in acne research [1, 4, 14–16]. Antimicrobial peptides (AMPs) are regarded as alternatives to traditional antibiotics in the treatment of infectious and inflammatory skin diseases [15, 17]. The socalled ‘nature’s antibiotics’ are cationic, amphiphilic peptides built up by 6–50 amino acids. They interact with anionic phospholipid membranes and show a broadspectrum of antimicrobial activity against a wide range of pathogens including bacteria and fungi [17, 18]. AMPs might contribute to overcoming the increasing problems of antibiotic resistance [19, 20], based on their diversity, safety and mode of action by directly targeting and destroying membranes even in multidrug-resistant pathogens [15, 19, 20]. AMPs are part of the innate immune system of mammals, forming an initial barrier to pathogenic influences before the adaptive immune system develops [21, 22]. In humans they are predominantly produced by keratinocytes in the upper skin layers [18, 22]. In innate immune defense, AMPs play an important role in epithelial barrier protection [18]. AMPs also play a role in some inflammatory processes, as their release provides innate antibiotic-like action against infectious pathogens [22]. One of the oldest clinically used AMP is tyrothricin [17], produced by Bacillus brevis [23, 24]. This polypeptide antibiotic substance consists of the two cyclic decapeptides, gramicidin S (22%) and tyrocidine A (78%) [24–26]. Both peptides have broad bactericidal activity 2
Skin Pharmacol Physiol 2016;29:1–8 DOI: 10.1159/000439439
against Gram-positive bacteria due to intercalation of the peptides into bacterial membranes [17, 27]. Topical tyrothricin 0.1% has been successfully used for the treatment of small, superficial, and infectious wounds by promoting wound healing for more than 70 years [28, 29]. Available evidence suggests that tyrothricin has good tolerability and no potential to induce bacterial resistance [25, 30–32]. Recently, the antimicrobial effectiveness of tyrothricin against Propionibacterium acnes was demonstrated in vitro [33]. Therefore, this AMP might be a potential candidate for acne treatment. The purpose of this clinical study was to investigate the efficacy and tolerability of topical tyrothricin 0.1% in the treatment of mild to severe acne vulgaris of the papulopustular type compared to two established topical acne treatments.
Materials and Methods Study Design This 25-day, exploratory, active comparator-controlled, randomized, observer-blind, intraindividual, monocenter clinical trial was conducted at the Charité – Universitätsmedizin Berlin, Department of Dermatology and Allergy, Clinical Research Center for Hair and Skin Science, Berlin, Germany. Eligible patients were recruited from October 2013 to February 2014; the last patient completed the study on March 13, 2014. Randomization and Blinding The randomization process consisted of two parts. First, all patients were randomized in a 1:1 ratio to receive topical tyrothricin 0.1% (Engelhard Arzneimittel GmbH & Co. KG, Niederdorfelden, Germany) and either topical BPO 5% (Aknefug® Oxid mild 5%; Dr. August Wolff GmbH & Co. KG Arzneimittel, Bielefeld, Germany) or the combination of clindamycin + BPO (Duac® Akne Ge; GlaxoSmithKline GmbH & Co. KG, Berlin, Germany) as comparator treatments on the face. Further, patients were also randomized in a 1:1 ratio to receive the respective comparator treatment on the right or left half-face. For allocation of the treatments, a computer-generated list was used. Randomization was performed successively using sealed randomization envelopes. Investigators involved in the study assessments were blinded to the identity and allocation of the treatments. Patients Male and female nonsmoking patients aged 18–25 years with a diagnosed mild to severe acne papulopustulosa, defined as an Investigator’s Static Global Assessment (ISGA) score of 2–4 [34, 35], were included after receiving thorough information on the study aim and procedure, and giving their written informed consent. Another inclusion criterion was that the number of inflammatory and noninflammatory acne lesions on one half-face was not greater than twice the number of the lesions on the other half-face. The main exclusion criteria were more than 2 nodulocystic lesions on each side of the face, treatment with systemic (4 weeks before ran-
Richter/Trojahn/Hillmann/Dobos/ Stroux/Kottner/Blume-Peytavi
Assessed for eligibility (n = 27) Enrollment
Excluded (n = 3) Not meeting inclusion criteria (n = 1) Noncompliance (n = 1) Back-up screening (n = 1)
Allocation
Discontinued study (n = 1)
Analysis
Allocated to tyrothricin 0.1% (Tyrosur® Gel) vs. combination of clindamycin + BPO (Duac® Acne Gel) (n = 12)
Follow-up
Randomized (n = 24)
Allocated to tyrothricin 0.1% (Tyrosur® Gel) vs. BPO 5% (Aknefug® Oxid mild 5%) (n = 12)
Reason: edema/allergic reaction due to comparator product
Analyzed (n = 11)
Analyzed (n = 12)
Excluded from analysis from day 8 onwards (study discontinuation due to AE) (n = 1)
Fig. 1. Flow of participants.
domization) or topical (2 weeks before randomization) anti-inflammatory drugs, treatment with drugs that are known to exacerbate acne (e.g. high doses of certain vitamins, haloperidol, halogens, lithium) for 3 months before randomization, smoothing or ablative procedures within 3 months before randomization, known hypersensitivity against tyrothricin, BPO or clindamycin, intensive UV exposure within 4 weeks before randomization, pregnancy, and lactation. Ethical Approval Prior to the study start, the protocol and the patient informed consent form were approved by the independent Ethics Committee of the State Office of Health and Social Affairs Berlin. The study was registered at the European Union Drug Regulating Authorities Clinical Trials Database (EudraCT 2013-001716-30; https://eudract.ema.europa.eu/). The study was conducted according to the principles of the Declaration of Helsinki (1996) and Good Clinical Practice Guidelines (1996). All patients provided written informed consent.
applied without investigator access. ISGA scoring and lesion counting were performed by trained investigators on days 1 and 25. Study Outcomes The study outcomes were inflammatory, noninflammatory, and total lesion counts as well as ISGA scores per half face. These were obtained at baseline, days 4, 8, 12, 15, 18, 22 and at the end of the study (day 25). Furthermore, dermal tolerability and safety were assessed by recording adverse events (AEs) throughout the study from screening until day 25.
Assessments Treatments were applied according to product information once daily in the evening by an unblinded study nurse on the respective facial side of the patient, avoiding the median line to prevent translocation of investigational products. Further, the perimucosal skin around the eyes and lips was not treated. Patients were seen daily during the course of the study. The study products were
Statistical Analysis A sample size of 12 patients per treatment group was regarded as appropriate due to the exploratory study design. For all efficacy outcomes, comparisons between treatments were based on 95% CI for intraindividual differences or differences between treatments. Generalized estimating equations (GEE) for analysis concerning the development over the entire time course with day and site/ treatment as intraindividual variables and lesion counts as the dependent variable were conducted. Interactions in terms of day and site/treatment were included into the GEE models to analyze different patterns of development over time. Tyrothricin 0.1% served as the reference parameter for the comparator treatments. All p values were considered to be descriptive. Analysis was done according to the originally assigned groups. IBM SPSS Statistics 22.0 was used for statistical analysis.
Topical Tyrothricin 0.1% in Acne Vulgaris
Skin Pharmacol Physiol 2016;29:1–8 DOI: 10.1159/000439439
3
Table 1. Demographic and baseline characteristics
Inflammatory lesion count (n)
25
Tyrothricin 0.1% Clindamycin + BPO 5% BPO 5%
20 15 10 5
a
0
5
10
Day
15
20
25
Age, years Mean Range BMI, mean (SD) Female, n Phototype, n II III
Noninflammatory lesion count (n)
a
40
30 25 Tyrothricin 0.1% Clindamycin + BPO 5% BPO 5%
20 15
0
5
10
Day
Total lesion count (n)
15
20
25
Tyrothricin 0.1% Clindamycin + BPO 5% BPO 5%
60 50 40 30 0
5
10
Day
15
20
25
Fig. 2. Changes in inflammatory lesion counts (a), noninflammatory lesion counts (b), and total lesion counts (c).
Results
Patient Disposition A total of 24 patients were randomly assigned to one of two treatment regimens (fig. 1). Using a split-face design, 12 of the 24 patients received tyrothricin 0.1% and BPO 5%, and 12 patients received tyrothricin 0.1% and a 4
Tyrothricin Totala 0.1% vs. (n = 24) BPO 5% (n = 12)
21.3 18–25 23.1 ( 2.5) 7
20.2 19–23 21.9 (3.3) 8
9 3
6 6
20.7 18–25 22.5 (2.9) 15 15 9
Includes all patients with at least one study treatment.
35
b
c
Tyrothricin 0.1% vs. clindamycin + BPO (n = 12)
Skin Pharmacol Physiol 2016;29:1–8 DOI: 10.1159/000439439
combination of clindamycin + BPO on each half-face. Twenty-three patients out of 24 completed the trial. In the tyrothricin 0.1% and clindamycin + BPO group, 11 of the 12 patients were analyzed; 1 patient was excluded from the study because of a persistent treatment-related AE on day 8. In the tyrothricin 0.1% and BPO 5% group, all patients were analyzed (fig. 1). Demographic and baseline clinical characteristics were comparable in both treatment groups (table 1). Comparison of Tyrothricin 0.1% versus Clindamycin + BPO At baseline, mean inflammatory lesion counts were 21.5 (SD 13.2) for tyrothricin 0.1% and 23.1 (SD 15.1) for clindamycin + BPO (table 2, fig. 2). Mean differences in inflammatory lesion counts between day 25 and baseline were –7.7 (95% CI: –11.7 to –3.7) for tyrothricin 0.1% and –12.3 (95% CI: –20.5 to –4.1) for clindamycin + BPO. Mean differences in noninflammatory lesion counts between day 25 and baseline were –6.5 (95% CI: –11.6 to –1.4) for tyrothricin 0.1% and –16.1 (95% CI: –24.6 to –7.6) for clindamycin + BPO. Mean baseline total lesion counts were 56.1 (SD 22.9) for tyrothricin 0.1% and 60.6 (SD 24.6) for clindamycin + BPO (table 2, fig. 2). Mean differences in total lesion count comparing day 25 with baseline were –14.2 (95% CI: –21.1 to –7.3) in tyrothricin 0.1% and –28.4 (95% CI: –39.9 to –16.9) in clindamycin + BPO (table 2, fig. 2). The ISGA score was reduced by 0.3 in tyrothricin 0.1% and 0.5 in clindamycin + BPO (table 2, fig. 2). Comparing both treatments, we found a statistically stronger reduction in inflammatory, noninflammatory, and total lesion count over time with clindamyRichter/Trojahn/Hillmann/Dobos/ Stroux/Kottner/Blume-Peytavi
Table 2. Results of lesion counts and ISGA scores at days 1 (baseline) and 25 (end of study)
Tyrothricin 0.1% (n = 24)a
Clindamycin + BPO (n = 12)b
BPO 5% (n = 12)
mean (SD)
95% CI
mean (SD)
95% CI
mean (SD)
95% CI
16.0 to 27.1 10.4 to 17.3 –11.7 to –3.7
23.1 (15.1) 10.8 (7.8) –12.3 (12.9)
13.5 to 32.7 5.8 to 15.7 –20.5 to –4.1
19.9 (10.4) 9.8 (4.7) –10.2 (8.1)
13.3 to 26.5 6.8 to 12.7 –15.3 to –5.0
27.8 to 41.3 23.2 to 32.9 –11.6 to –1.4
37.5 (18.5) 21.4 (9.8) –16.1 (13.4)
25.7 to 49.3 15.2 to 27.7 –24.6 to –7.6
35.5 (17.0) 18.8 (18.8) –16.8 (14.8)
24.7 to 46.3 14.1 to 23.4 –26.2 to –7.3
46.4 to 65.8 34.2 to 49.5 –21.1 to –7.3
60.6 (24.6) 32.2 (14.9) –28.4 (18.1)
44.9 to 76.2 22.7 to 41.7 –39.9 to –6.9
55.4 (23.4) 28.5 (10.6) –26.9 (20.0)
40.6 to 70.3 21.8 to 35.2 –39.6 to –14.2
Inflammatory lesion count Day 1 21.5 (13.2) Day 25 13.8 (8.2) – 7.7 (9.6) Mean differencec Noninflammatory lesion count Day 1 34.5 (15.9) Day 25 28.0 (11.4) – 6.5 (12.1) Mean differencec Total lesion count Day 1 56.1 (22.9) Day 25 41.9 (18.2) Mean differencec –14.2 (16.4) ISGA Day 1 2.7 (0.7) Day 25 2.4 (0.8) – 0.3 (0.5) Mean differencec a
2.4 to 3.0 2.1 to 2.7 – 0.5 to –0.1
2.8 (0.8) 2.3 (1.0) – 0.5 (0.5)
2.3 to 3.4 1.6 to 2.9 – 0.9 to –0.3
2.6 (0.5) 2.3 (0.8) – 0.3 (0.5)
2.3 to 2.9 1.8 to 2.7 – 0.6 to –0.02
n = 23 from day 8 onwards. b n = 11 from day 8 onwards. c Mean difference = day 2 – day 1.
Table 3. Inflammatory, noninflammatory, and total lesion counts over time in the adjusted analysis
Regression coefficient Inflammatory lesion count Constant Day BPO 5% group Clindamycin + BPO Tyrothricin 0.1% (= reference) BPO 5% × day Clindamycin + BPO × day Tyrothricin × day (= reference) Noninflammatory lesion count Constant Day BPO 5% group Clindamycin + BPO Tyrothricin 0.1% (= reference) BPO 5% × day Clindamycin + BPO × day Tyrothricin × day (= reference) Total lesion count Constant Day BPO 5% group Clindamycin + BPO Tyrothricin 0.1% (= reference) BPO 5% × day Clindamycin + BPO × day Tyrothricin × day (= reference)
Topical Tyrothricin 0.1% in Acne Vulgaris
95% CI
Wald χ2
p
2.952 –0.026 –0.026 0.076 0 –0.010 –0.028 0
2.733 to 3.170 –0.038 to 0.014 –0.355 to 0.302 –0.329 to 0.481 – –0.029 to 0.010 –0.055 to 0.002 –
700.066 17.998 0.025 0.134 – 0.959 4.306 –