Photodynamic therapy of acne vulgaris using 5-aminolevulinic acid 0.5% liposomal spray and intense pulsed light in combination with topical keratolytic agents

Nanocarriers in topical photodynamic therapy

INTRODUCTION

Photodynamic therapy (PDT) has gained significant attention due to its superiority over conventional treatments. In the context of skin cancers and nonmalignant skin diseases, topical application of photosensitizer formulations onto affected skin, followed by illumination, offers distinct advantages. Topical PDT simplifies therapy by providing easy access to the skin, increasing drug concentration within the target area, and confining residual photosensitivity to the treated skin. However, the effectiveness of topical PDT is often hindered by challenges such as limited skin penetration or photosensitizer instability. Additionally, the hypoxic tumor environment poses further limitations. Nanocarriers present a promising solution to address these challenges.

AREAS COVERED

The objective of this review is to comprehensively explore and highlight the role of various nanocarriers in advancing topical PDT for the treatment of skin diseases. The primary focus is to address the challenges associated with conventional topical PDT approaches and demonstrate how nanotechnology-based strategies can overcome these challenges, thereby improving the overall efficiency and efficacy of PDT.

EXPERT OPINION

Nanotechnology has revolutionized the field of PDT, offering innovative tools to combat the unfavorable features of photosensitizers and hurdles in PDT. Nanocarriers enhance skin penetration and stability of photosensitizers, provide controlled drug release, reduce needed dose, increase production of reactive oxygen species, while reducing side effects, thereby improving PDT effectiveness.

Fluorescence Spectroscopy of Porphyrins and Phthalocyanines: Some Insights into Supramolecular Self-Assembly, Microencapsulation, and Imaging Microscopy

The molecular interactions of anionic tetrasulfonate phenyl porphyrin (TPPS) with poly(amido amine) (PAMAM) dendrimers of generation 2.0 and 4.0 (G2 and G4, respectively) forming H- or J-aggregates, as well as with human and bovine serum albumin proteins (HSA and BSA), were reviewed in the context of self-assembly molecular complementarity. The spectroscopic studies were extended to the association of aluminum phthtalocyanine (AlPCS4) detected with a PAMAM G4 dendrimer with fluorescence studies in both steady state and dynamic state, as well as due to the fluorescence quenching associated to electron-transfer with a distribution of lifetimes. The functionalization of TPPS with peripheral substituents enables the assignment of spontaneous pH-induced aggregates with different and well-defined morphologies. Other work reported in the literature, in particular with soft self-assembly materials, fall in the same area with particular interest for the environment. The microencapsulation of TPPS studies into polyelectrolyte capsules was developed quite recently and aroused much interest, which is well supported and complemented by the extensive data reported on the Imaging Microscopy section of the Luminescence of Porphyrins and Phthalocyanines included in the present review.

Hexyl-aminolevulinate ethosome-mediated photodynamic therapy against acne: in vitro and in vivo analyses

Biofilm formation by Propionibacterium acnes is known to cause failure of anti-acne treatment. Conventional therapies for acne are typically inadequate. Accordingly, in this study, we evaluated the therapeutic potential of photodynamic therapy (PDT) using hexyl-aminolevulinate (HAL)-loaded ethosomes (ESs) against the biofilms of P. acnes in vitro and P. acnes-induced inflammatory acne model in vivo. The antibacterial effects of HAL ESs were evaluated using XTT colorimetric assays and scanning electron microscopic observations of morphological changes. P. acnes was intradermally injected into the ears of Sprague-Dawley rats, and the anti-inflammatory effects of HAL ESs were measured by determining changes in appearance, histology, and the antibacterial effects by P. acnes abundance in ear tissues compared with blank control ESs, HAL alone, and 5-aminolevulinic acid (ALA) alone. The highest reduction in viability in P. acnes biofilms was observed after treatment with 5 mg/mL HAL ESs. Notably, blank control ESs also showed significant inhibitory effects. Furthermore, HAL ESs had superior therapeutic effects in the rat model compared with HAL or ALA solutions. The observed therapeutic effects of HAL ESs against P. acnes biofilms and P. acnes-induced inflammation suggest that PDT with HAL-loaded ESs may have potential applications in the treatment of acne.

Analysis of trends and status of physician-based evaluation methods in acne vulgaris from 2000 to 2019

Various evaluation methods for acne severity have been used without standardization, and the diversity of acne outcome measures is an obstacle to the integrated analysis of various acne studies. In this study, we sought to investigate physician-based evaluation methods used in clinical studies of acne vulgaris and to determine differences according to time, region and study design. PubMed was searched for articles on acne published from January 2000 to June 2019 in five dermatology journals: Journal of the American Academy of Dermatology, JAMA Dermatology, British Journal of Dermatology, Journal of the European Academy of Dermatology and Venereology and Acta Dermato-Venereologica. A total of 186 articles with acne evaluation methods were selected. Among the selected studies, region, study design, type of intervention and the number of subjects were identified and analyzed. Articles from 2010 to 2019 used Investigator Global Assessment (IGA; odds ratio [OR], 5.808; 95% CI, 1.894-17.811) more often and the Leeds technique (OR, 0.282; 95% CI, 0.098-0.812) less often compared with articles from 2000 to 2009. Controlled experimental studies preferred lesion counting (OR, 238.637; 95% CI, 46.795-1216.954), IGA (OR, 9.177; 95% CI, 3.053-27.586) and Leeds Revised Acne Grading System (LRAGS; OR, 10.844; 95% CI, 3.050-38.559) compared with observational studies. North American studies applied lesion counting (OR, 4.573; 95% CI, 1.173-17.836) and IGA (OR, 11.330; 95% CI, 3.487-36.818) more often and LRAGS (OR, 0.171; 95% CI, 0.039-0.758) less often compared with European studies. This study demonstrated the diversity and heterogeneity of acne outcome measures even in highly influential dermatology journals. This is due to the limitations of current methods and suggests the importance of developing a core outcome measure.

Photodynamic therapy for skin cancer: How to enhance drug penetration?

Photodynamic therapy (PDT) induced by protoporphyrin IX (PpIX) has been widely used in dermatological practices such as treatment of skin cancers. Clearance rate depends on different factors such as light irradiation, skin oxygenation and drug penetration. The poor penetration of 5-aminolevulinic acid (5-ALA) with topical application is limited and restrains the production of PpIX which could restrict PDT outcomes. This review will focus on techniques already used to enhance drug penetration in human skin, and will present their results, advantages, and drawbacks. Chemical and physical pretreatments will be discussed. Chemical pre-treatments comprise of drug formulation modification, use of agents that modify the heme cycle, enhance PpIX formation, and the combination of differentiation-promoting agent prior to PDT. On the other hand, physical pretreatments affect the skin barrier by creating holes in the skin or by removing stratum corneum. To promote drug penetration, iontophoresis and temperature modulation are interesting alternative methods. Cellular mechanisms enrolled during chemical or physical pretreatments have been investigated in order to understand how 5-ALA penetrates the skin, why it is preferentially metabolized in PpIX in tumour cells, and how it could be accumulated in deeper skin layers. The objective of this review is to compare clinical trials that use innovative technology to conventional PDT treatment. Most of these pretreatments present good or even better clinical outcomes than usual PDT.

Light therapies for acne

BACKGROUND

Acne vulgaris is a very common skin problem that presents with blackheads, whiteheads, and inflamed spots. It frequently results in physical scarring and may cause psychological distress. The use of oral and topical treatments can be limited in some people due to ineffectiveness, inconvenience, poor tolerability or side-effects. Some studies have suggested promising results for light therapies.

OBJECTIVES

To explore the effects of light treatment of different wavelengths for acne.

SEARCH METHODS

We searched the following databases up to September 2015: the Cochrane Skin Specialised Register, CENTRAL, MEDLINE, Embase and LILACS. We searched ISI Web of Science and Dissertation Abstracts International (from inception). We also searched five trials registers, and grey literature sources. We checked the reference lists of studies and reviews and consulted study authors and other experts in the field to identify further references to relevant randomised controlled trials (RCTs). We updated these searches in July 2016 but these results have not yet been incorporated into the review.

SELECTION CRITERIA

We included RCTs of light for treatment of acne vulgaris, regardless of language or publication status.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 71 studies, randomising a total of 4211 participants.Most studies were small (median 31 participants) and included participants with mild to moderate acne of both sexes and with a mean age of 20 to 30 years. Light interventions differed greatly in wavelength, dose, active substances used in photodynamic therapy (PDT), and comparator interventions (most commonly no treatment, placebo, another light intervention, or various topical treatments). Numbers of light sessions varied from one to 112 (most commonly two to four). Frequency of application varied from twice daily to once monthly.Selection and performance bias were unclear in the majority of studies. Detection bias was unclear for participant-assessed outcomes and low for investigator-assessed outcomes in the majority of studies. Attrition and reporting bias were low in over half of the studies and unclear or high in the rest. Two thirds of studies were industry-sponsored; study authors either reported conflict of interest, or such information was not declared, so we judged the risk of bias as unclear.Comparisons of most interventions for our first primary outcome 'Participant's global assessment of improvement' were not possible due to the variation in the interventions and the way the studies' outcomes were measured. We did not combine the effect estimates but rated the quality of the evidence as very low for the comparison of light therapies, including PDT to placebo, no treatment, topical treatment or other comparators for this outcome. One study which included 266 participants with moderate to severe acne showed little or no difference in effectiveness for this outcome between 20% aminolevulinic acid (ALA)-PDT (activated by blue light) versus vehicle plus blue light (risk ratio (RR) 0.87, 95% confidence interval (CI) 0.72 to 1.04, low-quality evidence). A study (n = 180) of a comparison of ALA-PDT (activated by red light) concentrations showed 20% ALA was no more effective than 15% (RR 1.05, 95% CI 0.96 to 1.15) but better than 10% ALA (RR 1.22, 95% CI 1.05 to 1.42) and 5% ALA (RR 1.47, 95% CI 1.19 to 1.81). The number needed to treat for an additional beneficial outcome (NNTB) was 6 (95% CI 3 to 19) and 4 (95% CI 2 to 6) for the comparison of 20% ALA with 10% and 5% ALA, respectively.For our second primary outcome 'Investigator-assessed changes in lesion counts', we combined three RCTs, with 360 participants with moderate to severe acne and found methyl aminolevulinate (MAL) PDT (activated by red light) was no different to placebo cream plus red light with regard to change in inflamed lesions (ILs) (mean difference (MD) -2.85, 95% CI -7.51 to 1.81), percentage change in ILs (MD -10.09, 95% CI -20.25 to 0.06), change in non-inflamed lesions (NILs) (MD -2.01, 95% CI -7.07 to 3.05), or in percentage change in NILs (MD -8.09, 95% CI -21.51 to 5.32). We assessed the evidence as moderate quality for these outcomes meaning that there is little or no clinical difference between these two interventions for lesion counts.Studies comparing the effects of other interventions were inconsistent or had small samples and high risk of bias. We performed only narrative synthesis for the results of the remaining trials, due to great variation in many aspects of the studies, poor reporting, and failure to obtain necessary data. Several studies compared yellow light to placebo or no treatment, infrared light to no treatment, gold microparticle suspension to vehicle, and clindamycin/benzoyl peroxide combined with pulsed dye laser to clindamycin/benzoyl peroxide alone. There were also several other studies comparing MAL-PDT to light-only treatment, to adapalene and in combination with long-pulsed dye laser to long-pulsed dye laser alone. None of these showed any clinically significant effects.Our third primary outcome was 'Investigator-assessed severe adverse effects'. Most studies reported adverse effects, but not adequately with scarring reported as absent, and blistering reported only in studies on intense pulsed light, infrared light and photodynamic therapies. We rated the quality of the evidence as very low, meaning we were uncertain of the adverse effects of the light therapies.Although our primary endpoint was long-term outcomes, less than half of the studies performed assessments later than eight weeks after final treatment. Only a few studies assessed outcomes at more than three months after final treatment, and longer-term assessments are mostly not covered in this review.

AUTHORS' CONCLUSIONS

High-quality evidence on the use of light therapies for people with acne is lacking. There is low certainty of the usefulness of MAL-PDT (red light) or ALA-PDT (blue light) as standard therapies for people with moderate to severe acne.Carefully planned studies, using standardised outcome measures, comparing the effectiveness of common acne treatments with light therapies would be welcomed, together with adherence to the Consolidated Standards of Reporting Trials (CONSORT) guidelines.

Dual Propionibacterium acnes therapy using skin penetration-enhanced liposomes loaded with a photosensitizer and an antibiotic

Various antibiotics and photosensitizers are used for Propionibacterium acnes therapy. However, the success rate of therapy is limited because of antibiotic resistance, side-effects of photodynamic therapy using photosensitizer and the low skin-penetration efficiency of antibiotics and photosensitizers. In this study, to enhance the skin penetration efficiency, maintain their photodynamic activity and induce dual antibacterial therapeutic effects, we prepare erythromycin and branched polyethyleneimin-hematoporphyrin (bPEI-HPP) conjugates were loaded into liposomes (cationic photosensitizer-erythromycin loaded liposomes, CP-L (bPEI-HPP 10 mg; CP-L 1 and 20 mg; CP-L 2)). The tissue penetration efficiency of CP-Ls was determined by the Franz cell diffusion system and fluorescence microscopy. The penetration efficiency of CP-Ls is greater than that of bPEI-HPP, unloaded cationic photosensitizer and free HPP because CP-Ls comprised phospholipids that are similar to the cell membrane lipid composition. For in vitro antibacterial effects, Propionibacterium acnes (P. acnes) were used. The loss of viability rate of P. acnes by CP-L 2 (95%) from the colony forming unit (CFU) assay, was 2.4-fold higher than erythromycin-loaded liposomes (39%) and 1.9-fold higher than bPEI-HPP-loaded liposomes (50%). Therefore, we suggest that polycationic photosensitizer and antibiotic-loaded liposomes have potential applications in clinical photodynamic anti-bacterial therapy.

Artificial daylight photodynamic therapy with "non-inflammatory" doses of hexyl aminolevulinate only marginally delays SCC development in UV-exposed hairless mice

Photodynamic therapy (PDT) is effective for actinic keratoses, but is associated with pain and post-treatment inflammation. Daylight-mediated PDT and PpIX-precursors at low concentrations reduce pain and inflammation intensity. The objective was to evaluate the effect of repeated low-concentration PDT combined with artificial daylight on SCC development. Mice (n = 265) were exposed to simulated solar UV-irradiation (UVR) 3 times weekly mimicking "summer-dose"-exposure (3 SED). Selected groups of mice received a "winter-dose"-exposure (0.6 SED) for the first 90 days. PDT was delivered with 0.1%, 0.05% and 0.02% hexyl aminolevulinate (HAL) cream and artificial daylight for 2.5 hours (6 J cm(-2)) in different treatment regimes (1-3 times weekly, 45-days intervals, days 1-180 and from day 180 onwards). The primary end-point was the time to first SCC (1 mm diameter). 0.1% HAL-PDT given 3 times weekly slightly delayed SCC development and induced minimal inflammation. In winter- and summer UVR-treatment regimes, 0.1% HAL PDT delayed the time to first SCC compared to control UVR and placebo-PDT when mice were PDT-treated on days 1-180 (median 213 vs. 199 days, p = 0.011) and from day 180 onwards (median 218 vs. 199 days, p = 0.006). PDT with 0.05% and 0.02% HAL did not influence SCC development (medians 206 days, p = ns). In summer UVR-exposed mice, 0.1% HAL-PDT marginally postponed the time to first SCC compared to control UVR (median 160 days) when treatments were given 3 times weekly for 180 days (median 166, p = 0.01), but not for 90 days (median 161, p = 0.112). In conclusion, repeated low-concentration HAL-PDT combined with artificial daylight is well-tolerated, but only marginally delays SCC development in mice.

Current evidence and applications of photodynamic therapy in dermatology

In photodynamic therapy (PDT) a photosensitizer – a molecule that is activated by light – is administered and exposed to a light source. This leads both to destruction of cells targeted by the particular type of photosensitizer, and immunomodulation. Given the ease with which photosensitizers and light can be delivered to the skin, it should come as no surprise that PDT is an increasingly utilized therapeutic in dermatology. PDT is used commonly to treat precancerous cells, sun-damaged skin, and acne. It has reportedly also been used to treat other conditions including inflammatory disorders and cutaneous infections. This review discusses the principles behind how PDT is used in dermatology, as well as evidence for current applications of PDT.

Photodynamic topical antimicrobial therapy for infected foot ulcers in patients with diabetes: a randomized, double-blind, placebo-controlled study--the D.A.N.T.E (Diabetic ulcer Antimicrobial New Topical treatment Evaluation) study

This study was designed to assess the antimicrobial effect and tolerability of a single dose of a photo-activated gel containing RLP068 in the treatment for infected foot ulcers in subjects with diabetes. A randomized, double-blind, parallel series, placebo-controlled phase IIa trial was performed with three concentrations of RLP068 (0.10, 0.30, and 0.50 %), measuring total and pathogen microbial load on Day 1 (before and 1 h after topical gel application and photoactivation with 689 nm red light), on Days 3, 8, and 15, as add-on to systemic treatment with amoxicillin and clavulanic acid. Blood samples were also drawn 1, 2, and 48 h after administration for the assessment of systemic drug absorption. The trial was performed on 62 patients aged ≥18 years, with type 1 or type 2 diabetes and infected foot ulcer, with an area of 2-15 cm(2) and a maximum diameter ≤4.6 cm. A dose-dependent reduction in total microbial load was observed (-1.92 ± 1.21, -2.94 ± 1.60, and -3.00 ± 1.82 LogCFU/ml for 0.10, 0.30, and 0.50 % RPL068 vs. -1.00 ± 1.02 LogCFU/ml with placebo) immediately after illumination, with a progressive fading of the effect during follow-up. No safety issues emerged from the analysis of adverse events. Systemic absorption of RLP068 was negligible. Photodynamic antimicrobial treatment with RLP068 of infected diabetic foot ulcers is well tolerated and produces a significant reduction in germ load. Further clinical trials are needed to verify the efficacy of this approach as add-on to systemic antibiotic treatment.

Photodynamic therapy with ablative carbon dioxide fractional laser in treatment of actinic keratosis

Background

Recently, photodynamic therapy (PDT) has been shown to be an effective first-line treatment for actinic keratosis (AK). However, a major limitation of PDT is the long incubation time required to allow penetration of the photosensitizer.

Objective

The aim of this study was to assess if pretreatment with an ablative carbon dioxide (CO₂) fractional laser can reduce the incubation time of the photosensitizer.

Methods

Initially, 29 patients with a total of 34 AK lesions were treated with an ablative CO₂ fractional laser at Ajou University Hospital between January and December 2010. Immediately after the laser treatment, topical 20% 5-aminolevulinic acid or methyl-aminolevulinate was applied to the AK lesions and incubated for 70 to 90 minutes. Then, the treated areas were illuminated with a red light source. Improvement was clinically or histologically assessed eight weeks after the treatment.

Results

In spite of the short incubation time, 24 lesions (70.6%) showed a complete response (CR) within three sessions of PDT (10 lesions a clinical CR and 14 lesions a clinical/histological CR). There were no significant side effects associated with the combination of ablative CO₂ fractional laser and PDT.

Conclusion

Ablative CO₂ fractional laser may be considered an additional treatment option for reducing the incubation time of the photosensitizer in PDT.

Photodynamic therapy with ablative carbon dioxide fractional laser for treating Bowen disease

BACKGROUND

Topical photodynamic therapy (PDT) has been increasingly used to treat malignant skin tumors including the Bowen disease. However, patients could be displeased with the long incubation time required for conventional PDT.

OBJECTIVE

We evaluated the efficacy and safety of PDT with a short incubation time of ablative CO2 fractional laser pretreatment for treating Bowen disease.

METHODS

Ten patients were included. Just before applying the topical photosensitizer, all lesions were treated with ablative CO2 fractional laser, following the application of methyl aminolevulinate and irradiation with red light (Aktilite CL 128). Histological confirmation, rebiopsy, and clinical assessments were performed. Adverse events were also recorded.

RESULTS

Five of the ten (50%) lesions showed a complete response (CR) within three PDT sessions. After four treatment sessions, all lesions except one penile shaft lesion (90%) achieved clinical and histological CR or clinical CR only. The average number of treatments to CR was 3.70±1.70. The treatments showed favorable cosmetic outcomes and no serious adverse events.

CONCLUSION

The results suggest that pretreatment with an ablative fractional CO2 laser before PDT has similar treatment efficacy and requires a shorter photosensitizer incubation time compared with the conventional PDT method.

Current status of liposomal porphyrinoid photosensitizers

The complete eradication of various targets, such as infectious agents or cancer cells, while leaving healthy host cells untouched, is still a great challenge faced in the field of medicine. Photodynamic therapy (PDT) seems to be a promising approach for anticancer treatment, as well as to combat various dermatologic and ophthalmic diseases and microbial infections. The application of liposomes as delivery systems for porphyrinoids has helped overcome many drawbacks of conventional photosensitizers and facilitated the development of novel effective photosensitizers that can be encapsulated in liposomes. The development, preclinical studies and future directions for liposomal delivery of conventional and novel photosensitizers are reviewed.

Liposomes in topical photodynamic therapy

INTRODUCTION

Topical photodynamic therapy (PDT) refers to topical application of a photosensitizer onto the site of skin disease which is followed by illumination and results in death of selected cells. The main problem in topical PDT is insufficient penetration of the photosensitizer into the skin, which limits its use to superficial skin lesions. In order to overcome this problem, recent studies tested liposomes as delivery systems for photosensitizers.

AREAS COVERED

This paper reviews the use of different types of liposomes for encapsulating photosensitizers for topical PDT. Liposomes should enhance the photosensitizers' penetration into the skin, while decreasing its absorption into systemic circulation. Only few photosensitizers have currently been encapsulated in liposomes for topical PDT: 5-aminolevulinic acid (5-ALA), temoporfin (mTHPC) and methylene blue.

EXPERT OPINION

Investigated liposomes enhanced the skin penetration of 5-ALA and mTHPC, reduced their systemic absorption and reduced their cytotoxicity compared with free drugs. Their high tissue penetration should enable the treatment of deep and hyperkeratotic skin lesions, which is the main goal of using liposomes. However, liposomes still do not attract enough attention as drug carriers in topical PDT. In vivo studies of their therapeutic effectiveness are needed in order to obtain enough evidence for their potential clinical use as carriers for photosensitizers in topical PDT.

[Physico-biological foundation of skin fluorescence--review]

Fluorescence is a peculiar aspect of photoluminescence. Some intrinsic components of the skin are fluorophores. Other synthetic components are metabolized into fluorophores. These characteristics may be used for identifying some specific aspects of skin physiopathology. Recent technological evolution has provided new devices bringing sensitive and specific information from the skin. This review presents a synthesis of the progress made in the field of fluorescence and specular reflexion of incident UV light on the skin.

Photodynamic therapy based on 5-aminolevulinic acid and its use as an antimicrobial agent

Exogenous 5-aminolevulinic acid (ALA) is taken up directly by bacteria, yeasts, fungi, and some parasites, which then induces the accumulation of protoporphyrin IX (PPIX). Subsequent light irradiation of PPIX leads to the inactivation of these organisms via photodamage to their cellular structures. ALA uptake and light irradiation of PPIX produced by host cells leads to the inactivation of other parasites, along with some viruses, via the induction of an immune response. ALA-mediated PPIX production by host cells and light irradiation result in the inactivation of other viruses via either the induction of a host cell response or direct photodynamic attack on viral particles. This ALA-mediated production of light-activated PPIX has been extensively used as a form of photodynamic therapy (PDT) and has shown varying levels of efficacy in treating conditions that are associated with microbial infection, ranging from acne and verrucae to leishmaniasis and onychomycosis. However, for the treatment of some of these conditions by ALA-based PDT, the role of an antimicrobial effect has been disputed and in general, the mechanisms by which the technique inactivates microbes are not well understood. In this study, we review current understanding of the antimicrobial mechanisms used by ALA-based PDT and its role in the treatment of microbial infections along with its potential medical and nonmedical applications.

New approaches in light/laser therapies and photodynamic treatment of acne

Acne is a domain in which the technology and understanding of light/laser therapeutic procedures have advanced considerably. The aim of the paper was to revisit adjunctive physical treatments of acne, including light/laser treatments and photodynamic therapy. This review summarizes findings about such treatment modalities with particular emphasis on efficacy and safety. A number of laser/light-based modalities have been developed to meet the increasing demand for new acne treatments. The current devices correspond, on the one hand, to light-emitting diode therapy and, on the other hand, to the 532-nm potassium titanyl phosphate laser, the 585- and 595-nm pulsed dye laser, the 1450-nm diode laser, the 1320-nm Nd:YAG laser and intense pulsed light. Photodynamic therapy is also available. It is claimed that light/laser treatments might induce a faster response compared with the 1-3 months needed for response to traditional oral and topical treatments. In conclusion, pulsed dye laser shows efficacy in some patients with mild to moderate acne. The relative effectiveness compared with other treatments is unconfirmed; from the published information, evidence-based efficacy assessment of light/laser therapies in acne remains almost impossible.

0.5% Liposome-encapsulated 5-aminolevulinic acid (ALA) photodynamic therapy for acne treatment

BACKGROUND

Photodynamic therapy using topical 5-aminolevulinic acid (ALA) has been successful in treating acne vulgaris, but sun avoidance for at least 48 hours after treatment is necessary due to the risk of post-treatment photosensitivity. Recently, a lower concentration of liposome-encapsulated 5-ALA was introduced to minimize this risk.

OBJECTIVES

To evaluate the efficacy and safety of liposome-encapsulated 0.5% 5-ALA in the photodynamic therapy of inflammatory acne and its effects on sebum secretion in Asian skin.

METHODS

Thirteen Korean subjects with inflammatory acne were administered 0.5% ALA spray before photoradiation treatment. Photoradiation was performed at 3.5-6.0 J/cm(2) three times during each of two visits, performed 2 weeks apart. Improvement of acne was evaluated subjectively and objectively based on the Korean Acne Grading System. Sebum secretion was measured quantitatively at each visit.

RESULTS

The mean reduction in acne grade at the end of the treatment was 43.2%. Of the patients, 69.2% reported improvements in subjective skin oiliness, but fewer showed objective reductions in sebum secretion as determined by the Sebumeter® SM10. No serious adverse events were observed.

CONCLUSION

Photodynamic therapy using liposome-encapsulated 0.5% 5-ALA improved inflammatory acne with minimal side effects in Asians.