Assessing effectiveness in acne clinical trials: steps towards a core outcome measure set.

BACKGROUND: Acne ranks second to dermatitis in terms of global burden of skin disease. As such, it is essential that data on treatment efficacy are generated in a way that maximizes the opportunity for comparison among treatments. Interest in developing core outcome sets for use in clinical trials to standardize data collection in skin disease is surging. OBJECTIVES: The goal of this review is to provide an update on the efforts underway, challenges encountered and future directions in the development of an acne core outcome measure set for use in clinical trials. METHODS: The activities of the Acne Core Outcomes Research Network (ACORN) are presented in the context of currently acceptable methodologies for core outcome set development. CONCLUSIONS: Emphasis is placed on following a rigorous methodology, involving patients and recognizing a role for emerging technologies.

AGREE II assessments of recent acne treatment guidelines: how well do they reveal trustworthiness as defined by the U.S. Institute of Medicine criteria?

BACKGROUND: Up-to-date, trustworthy guidelines are a widely relied upon means of promoting excellent patient care. OBJECTIVES: To determine the quality of recently published acne treatment guidelines by utilizing the Appraisal of Guidelines for Research and Evaluation (AGREE) II Reporting Checklist, the U.S. Institute of Medicine's (IOM) criteria of trustworthiness, the red flags of Lenzer et al. and CheckUp. METHODS: Systematic searches were conducted in bibliographic databases, guideline depositories and using Google to identify acne treatment guidelines published since 2013. Six assessors independently scored each guideline using the AGREE II Reporting Checklist. Guidelines were concomitantly assessed for trustworthiness using the IOM criteria and for the red flags of Lenzer et al., indicative of potential bias. Updates were screened using CheckUp. RESULTS: Eight guidelines were identified, two of which were updates. Lowest scoring AGREE II domains across all guidelines were applicability (six poor, one fair, one average) and rigour (four poor, one fair, three average). Two of the three highest-scoring guidelines were developed using AGREE II. No guideline fully met each IOM criterion and all raised at least one red flag indicative of potential bias. One updated guideline did not address seven of 16 items on CheckUp and the other did not address four. Patient involvement in guideline development was minimal. CONCLUSIONS: Use of the AGREE II instrument during guideline development did not have as great an effect on guideline quality as might be expected. There is considerable room for improvement in acne treatment guidelines in order to satisfy the IOM trustworthiness criteria and avoid bias.

The management of acne vulgaris in primary care: a cohort study of consulting and prescribing patterns using the Clinical Practice Research Datalink.

BACKGROUND: Effective management of acne vulgaris in primary care involves support (usually provided over a number of consultations) and prescription of effective treatments. However, consulting and prescribing patterns for acne in primary care are not well described. OBJECTIVES: To describe the rate of primary-care consultations and follow-up consultations; prescribing patterns, including overall use of acne-related medications (ARMs); and initial and follow-up prescription for acne vulgaris in the U.K. METHODS: U.K. primary-care acne consultations and prescriptions for ARMs were identified in the Clinical Practice Research Datalink. Annual consultation rates (between 2004 and 2013) by age and sex, new consultations and consultations in the subsequent year were calculated, along with prescribing trends - during a new consultation and over the subsequent 90 days and year - using the number of registered patients as the denominator. RESULTS: Two-thirds (66·1%) of patients who had a new acne consultation had no further acne consultations in the subsequent year. Overall 26·7%, 24·9%, and 23·6% and 2·8% of patients were prescribed no ARM, an oral antibiotic, a topical antibiotic or an oral plus topical antibiotic, respectively, during a new acne consultation. In total 60·1% and 38·6% of patients prescribed an ARM received no further ARM prescriptions in the following 90 days and 1 year, respectively, despite most prescriptions being for 2 months or less. Prescribing rates for lymecycline and topical combined clindamycin and benzoyl peroxide increased substantially between 2004 and 2013. There were no important changes in consultation rates between 2004 and 2013. CONCLUSIONS: These data suggest that patients with acne are receiving a suboptimal initial choice of ARMs, longitudinal care and prescribing.

Tert-butyl benzoquinone: mechanism of biofilm eradication and potential for use as a topical antibiofilm agent.

OBJECTIVES: Tert-butyl benzoquinone (TBBQ) is the oxidation product of tert-butyl hydroquinone (TBHQ), an antimicrobial food additive with >40 years of safe use. TBBQ displays potent activity against Staphylococcus aureus biofilms in vitro. Here, we report on studies to further explore the action of TBBQ on staphylococcal biofilms, and provide a preliminary preclinical assessment of its potential for use as a topical treatment for staphylococcal infections involving a biofilm component. METHODS: The antibacterial properties of TBBQ were assessed against staphylococci growing in planktonic culture and as biofilms in the Calgary Biofilm Device. Established assays were employed to measure the effects of TBBQ on biofilm structure and bacterial membranes, and to assess resistance potential. A living-skin equivalent was used to evaluate the effects of TBBQ on human skin. RESULTS: TBBQ eradicated biofilms of S. aureus and other staphylococcal species at concentrations ≤64 mg/L. In contrast to other redox-active agents exhibiting activity against biofilms, TBBQ did not cause substantial destructuring of the biofilm matrix; instead, the antibiofilm activity of the compound was attributed to its ability to kill slow- and non-growing cells via membrane perturbation. TBBQ acted synergistically with gentamicin, did not damage a living-skin equivalent following topical application and exhibited low resistance potential. CONCLUSIONS: The ability of TBBQ to eradicate biofilms appears to result from its ability to kill bacteria regardless of growth state. Preliminary evaluation suggests that TBBQ represents a promising candidate for development as a topical antibiofilm agent.

Redox-active compounds with a history of human use: antistaphylococcal action and potential for repurposing as topical antibiofilm agents.

OBJECTIVES: To investigate the antistaphylococcal/antibiofilm activity and mode of action (MOA) of a panel of redox-active (RA) compounds with a history of human use and to provide a preliminary preclinical assessment of their potential for topical treatment of staphylococcal infections, including those involving a biofilm component. METHODS: Antistaphylococcal activity was evaluated by broth microdilution and by time-kill studies with growing and slow- or non-growing cells. The antibiofilm activity of RA compounds, alone and in combination with established antibacterial agents, was assessed using the Calgary Biofilm Device. Established assays were used to examine the membrane-perturbing effects of RA compounds, to measure penetration into biofilms and physical disruption of biofilms and to assess resistance potential. A living skin equivalent model was used to assess the effects of RA compounds on human skin. RESULTS: All 15 RA compounds tested displayed antistaphylococcal activity against planktonic cultures (MIC 0.25-128 mg/L) and 7 eradicated staphylococcal biofilms (minimum biofilm eradication concentration 4-256 mg/L). The MOA of all compounds involved perturbation of the bacterial membrane, whilst selected compounds with antibiofilm activity caused destructuring of the biofilm matrix. The two most promising agents [celastrol and nordihydroguaiaretic acid (NDGA)] in respect of antibacterial potency and selective toxicity against bacterial membranes acted synergistically with gentamicin against biofilms, did not damage artificial skin following topical application and exhibited low resistance potential. CONCLUSIONS: In contrast to established antibacterial drugs, some RA compounds are capable of eradicating staphylococcal biofilms. Of these, celastrol and NDGA represent particularly attractive candidates for development as topical antistaphylococcal biofilm treatments.

Interleukin-10 secretion from CD14+ peripheral blood mononuclear cells is downregulated in patients with acne vulgaris.

BACKGROUND: Acne is a common chronic inflammatory dermatosis of the pilosebaceous unit. It is characterized by seborrhoea, comedone formation and an inflammatory response consistent with defective cellular immunity to Propionibacterium acnes. OBJECTIVES: The objective of this study was to investigate the immune reactivity of patients with acne compared with healthy controls by examining the response of peripheral blood mononuclear cells (PBMCs) to stimulation with P. acnes. Particular focus was placed upon measuring the production of interleukin (IL)-10, which has an established immunoregulatory role. PATIENTS AND METHODS: Venous blood was collected from 47 patients with acne and 40 age- and sex-matched healthy controls with no prior history of acne. PBMCs were cultured and their cytokine response to P. acnes investigated. RESULTS: Proinflammatory IL-8 and tumour necrosis factor (TNF)-alpha secretion from PBMCs was higher in patients with acne when stimulated with P. acnes. In contrast, a statistically significant reduction in PBMC secretion of anti-inflammatory IL-10 in patients with acne was identified. The impaired production of IL-10 by PBMCs from patients with acne was confined to CD14+ cells presumed to be monocytes. The ability of CD14 cells from patients with acne to phagocytose P. acnes bacteria was also observed to be defective but the addition of exogenous IL-10 to PBMC cultures restored phagocytic activity. CONCLUSIONS: These data suggest that patients with acne have a proinflammatory cytokine milieu and crucially are unable to contain early inflammatory changes due to a specific defect in immunosurveillance, namely low monocyte IL-10 production. Our observations raise the possibility that acne therapeutics might profitably target IL-10 both as a regulator of proinflammatory cytokines and in augmenting the CD14+ cell phagocytic response.

Randomised controlled multiple treatment comparison to provide a cost-effectiveness rationale for the selection of antimicrobial therapy in acne.

OBJECTIVES: To determine the relative efficacy and cost-effectiveness of five of the most commonly used antimicrobial preparations for treating mild to moderate facial acne in the community; the propensity of each regimen to give rise to local and systemic adverse events; whether pre-existing bacterial resistance to the prescribed antibiotic resulted in reduced efficacy; and whether some antimicrobial regimens were less likely to give rise to resistant propionibacterial strains. DESIGN: This was a parallel group randomised assessor-blind controlled clinical trial. It was a pragmatic design with intention-to-treat analysis. All treatments were given for 18 weeks, after a 4-week treatment free period. Outcomes were measured at 0, 6, 12 and 18 weeks. SETTING: Primary care practices and colleges in and around Nottingham and Leeds, and one practice in Stockton-on-Tees, England. PARTICIPANTS: Participants were 649 people aged 12--39 years, all with mild to moderate inflammatory acne of the face. INTERVENTIONS: Study participants were randomised into one of five groups: 500 mg oral oxytetracycline (non-proprietary) twice daily (b.d.) + topical vehicle control b.d.; 100 mg oral Minocin MR (minocycline) once daily (o.d.) + topical vehicle control b.d.; topical Benzamycin (3% erythromycin + 5% benzoyl peroxide) b.d. + oral placebo o.d.; topical Stiemycin (2% erythromycin) o.d. + topical Panoxyl Aquagel (5% benzoyl peroxide) o.d. + oral placebo o.d., and topical Panoxyl Aquagel (5% benzoyl peroxide) b.d. + oral placebo o.d. (the active comparator group). MAIN OUTCOME MEASURES: The two primary outcome measures were: (1) the proportion of patients with at least moderate self-assessed improvement as recorded on a six-point Likert scale, and (2) change in inflamed lesion count (red spots). RESULTS: The best response rates were seen with two of the topical regimens (erythromycin plus benzoyl peroxide administered separately o.d. or in a combined proprietary formulation b.d.), compared with benzoyl peroxide alone, oxytetracycline (500 mg b.d.) and minocycline (100 mg o.d.), although differences were small. The percentage of participants with at least moderate improvement was 53.8% for minocycline (the least effective) and 66.1% for the combined erythromycin/benzoyl peroxide formulation (the most effective); the adjusted odds ratio for these two treatments was 1.74 [95% confidence interval (CI) 1.04 to 2.90]. Similar efficacy rankings were obtained using lesion counts, acne severity scores and global rating by assessor. Benzoyl peroxide was the most cost-effective and minocycline the least cost-effective regimen (ratio of means 12.3; difference in means -0.051 units/GBP, 95% CI -0.063 to -0.039). The efficacy of oxytetracycline was similar to that of minocycline, but at approximately one-seventh of the cost. For all regimens, the largest reductions in acne severity were recorded in the first 6 weeks. Reductions in disability scores using the Dermatology Quality of Life Scales were largest for both topical erythromycin-containing regimens and minocycline. The two topical erythromycin-containing regimens produced the largest reductions in the prevalence and population density of cutaneous propionibacteria, including antibiotic-resistant variants, and these were equally effective in participants with and without erythromycin-resistant propionibacteria. The clinical efficacy of both tetracyclines was compromised in participants colonised by tetracycline-resistant propionibacteria. None of the regimens promoted an overall increase in the prevalence of antibiotic-resistant strains. Systemic adverse events were more common with the two oral antibiotics. Local irritation was more common with the topical treatments, particularly benzoyl peroxide. Residual acne was present in most participants (95%) at the end of the study. CONCLUSIONS: The response of mild to moderate inflammatory acne to antimicrobial treatment in the community is not optimal. Only around half to two-thirds of trial participants reported at least a moderate improvement over an 18-week study period; extending treatment beyond 12 weeks increased overall benefit slightly. Around one-quarter dropped out when using such treatments, and 55% sought further treatment after 18 weeks. Topical antimicrobial therapies performed at least as well as oral antibiotics in terms of clinical efficacy. Benzoyl peroxide was the most cost-effective and minocycline the least cost-effective therapy for facial acne. The efficacy of all three topical regimens was not compromised by pre-existing propionibacterial resistance. Benzoyl peroxide was associated with a greater frequency and severity of local irritant reactions. It is suggested that the use of a combination of topical benzoyl peroxide and erythromycin gives less irritation and better quality of life. There was little difference between erythromycin plus benzoyl peroxide administered separately and the combined proprietary formulation in terms of efficacy or local irritation, except that the former was nearly three times more cost-effective. The data on cost-effectiveness, and outcomes in patients with resistant propionibacterial floras, did not support the first line use of minocycline for mild to moderate inflammatory acne of the face. Three priority areas for clinical research in acne are: defining end-points in acne trials (i.e. what is a satisfactory outcome?); developing and validating better patient-based measures for assessing treatment effects on facial and truncal acne; and exploring patient characteristics that may modify treatment effects (efficacy and tolerability).

Pro-inflammatory levels of interleukin-1 alpha-like bioactivity are present in the majority of open comedones in acne vulgaris.

The factors that initiate the inflammatory response in acne are not known. The presence of pro-inflammatory cytokines in acne comedones was therefore investigated. One hundred eight open comedones were collected from 18 untreated acne patients (10 male, 8 female). Each comedone was homogenized and centrifuged, and the supernatant was analyzed for bioactive and immunochemically detectable IL-1 alpha, IL-1 beta, and TNF alpha. Viable counts of propionibacteria, staphylococci, and Malassezia spp. were determined in the comedone pellet. Bioactive IL-1 alpha-like material was demonstrated in 76% of open comedones (range of 23-4765 pg IL-1 alpha-like bioactivity/mg of comedone material). In 58% of comedones, levels exceeded 100 pg/mg. There was no correlation between IL-1 alpha-like bioactivity and IL-1 alpha determined immunochemically. Bioactive IL-1 beta was not detected in any comedones. Twenty-four percent contained low levels of immunochemical IL-1 beta (range 12-103 pg IL-1 beta/mg comedone material). Bioactive TNF alpha was detected in three comedones with a further five comedones containing immunochemical TNF alpha (range of 61-820 pg TNF alpha/mg comedone material). The majority of open comedones (97%) contained microorganisms. There was, however, no significant correlation (Spearman's rank) between levels of any cytokine, in particular IL-1 alpha-like bioactivity, and numbers of microorganisms. Thus, bioactive IL-1 alpha-like material in the majority of open comedones may be concerned in the initiation of inflammation in acne following spongiosis or rupture of the pilosebaceous follicle wall.

Modulation of comedonal levels of interleukin-1 in acne patients treated with tetracyclines.

To understand the basis for the anti-inflammatory activity of tetracyclines in acne, we compared the cytokine profiles [interleukin 1 (IL-1) alpha and beta, tumor necrosis factor (TNF) alpha, and IL-6] and bacterial flora of 66 open comedones removed from eleven patients before and after at least 8 weeks treatment with either tetracycline or minocycline. Pre-treatment, the only cytokine regularly recovered from comedones was bioactive IL-1 alpha-like material. The mean concentration of IL-1 alpha-like bioactivity/mg comedonal material rose from 272.0 +/- 88.6 pg to 844.3 +/- 196.7 pg following treatment (p < 0.05, Wilcoxon matched pairs). All six minocycline-treated patients showed an increase in bioactive IL-1 alpha-like material compared with three of five tetracycline-treated patients. The incidence (p < 0.001, chi 2) and concentration (p < 0.05, Wilcoxon) of immunochemical IL-beta were also raised post-treatment, although significantly more patients assigned to minocycline therapy had detectable levels of this cytokine before therapy was initiated. However, the mean concentration of IL-1 beta/mg comedonal material post-treatment was similar in both groups (72.5 +/- 23.3 pg for tetracycline-treated compared with 78.6 +/- 41.9 pg for minocycline-treated patients). The other cytokines were either absent (IL-6) or present in < 10% of comedones (TNF alpha) before and after therapy. Following treatment, only three of 11 patients showed a decrease of > or = 1 log10 in propionibacterial numbers/mg comedonal material, whereas six patients showed an increase of > 0.5 log10 in numbers of staphylococci. In eight patients, the increase or decrease in staphylococcal numbers correlated with the change in concentration of IL-1 alpha-like bioactivity. This is the first study to show an effect of antibiotic therapy on cytokine levels in vivo. Increased levels of IL-1 in comedones destined to become inflamed may enhance resolution and promote repair of the damaged follicular epithelium. Hence, these results provide further evidence of the augmentation of immune responses by tetracyclines and support the hypothesis that epidermal IL-1 plays a physiologic role in wound healing.

Minimal functional system required for expression of erythromycin resistance by msrA in Staphylococcus aureus RN4220.

Previous studies have suggested that inducible erythromycin (Er) resistance in staphylococci mediated by the plasmid-borne ABC-transporter msrA is dependent on additional unidentified chromosomally encoded transmembrane (TM) domains. The requirement for two S. aureus candidate sequences, stpC and smpC, highly similar to sequences adjacent to msrA on the original S. epidermidis plasmid was investigated. Deletion of the sequences by allelic replacement was accomplished by electroporation of S. aureus RN4220 with a nonreplicating suicide vector. S. aureus strains carrying a delta(stpC-smpC) mutation showed an identical ErR phenotype to those arising from single crossover events and unmutated RN4220 containing msrA. This proves that neither stpC nor smpC is required for ErR. To further define the minimal functional unit required for MSR, the control region within the leader sequence of msrA was deleted. This resulted in constitutive resistance to Er and type B streptogramins (Sg), proving that SgR does not require the presence of Er. Deletion constructs containing the N- or C-terminal ABC regions of MsrA did not confer ErR in RN4220 singly or in combination.

Identification of a chromosomally encoded ABC-transport system with which the staphylococcal erythromycin exporter MsrA may interact.

The energy-dependent efflux of erythromycin (Er) in staphylococci is due to the presence of msr A, which encodes an ATP-binding protein. MsrA is related to the multi-component ATP-binding cassette (ABC) transporters which characteristically also contain membrane-spanning domains. Since MsrA functions in a heterologous host in the absence of other plasmid-encoded products, the requirement for a transmembrane (TM) complex might be fulfilled by hijacking a chromosomally encoded protein. Two genes, stpA and smpA, were identified upstream from msrA on the original Staphylococcus epidermidis plasmid, encoding an ATP-binding protein and a hydrophobic TM protein, respectively. Sequences highly similar to stpA and smpA (stpB and smpB) were also found adjacent to a chromosomal copy of msrA in S. hominis. In Southern blots, internal fragments of stpA or smpA hybridized to the chromosome of the Ers S. aureus RN4220. Cloning and sequence analysis of the region identified revealed the presence of two genes, stpC and smpC, related to stpA and smpA. The deduced amino-acid sequences of the gene products showed that StpA and StpC were 85% identical, whereas SmpA and SmpC were 65% identical. A gene similar to msrA was not present in the S. aureus chromosome. There was no further sequence similarity outside these conserved regions. These results indicate that the chromosomes of S. hominis and S. aureus contain sequences encoding a potential TM protein with which MsrA might interact.

The use of PCR to isolate a putative ABC transporter from Saccharopolyspora erythraea.

A gene (ertX) encoding a putative ABC transporter was cloned from the erythromycin producer Saccharopolyspora erythraea, using PCR. The primers were based on regions of homology from ABC transporters which confer resistance to macrolide antibiotics. While ertX encodes a protein with a strong degree of similarity to other macrolide ABC transporters from streptomycetes and staphylococci, it did not confer resistance to erythromycin, tylosin, spiramycin, oleandomycin, josamcin, chalcomycin or midecamycin when subcloned into sensitive streptomycete hosts. Southern blot analysis suggested that ertX did not constitute part of the erythromycin gene cluster as identified to date.

Effects of tampon materials on the in-vitro physiology of a toxic shock syndrome strain of Staphylococcus aureus.

Seven materials used in the manufacture of tampons-four rayon, one modified rayon, one cotton and one carboxy-methyl cellulose (a modified cotton)-were compared for their effects in vitro on the physiology of a strain of Staphylococcus aureus isolated from a patient with Toxic Shock Syndrome. Experiments were performed in broth culture and, with the exception of two rayon samples, all of the materials tested reduced growth rate and cell yield compared with control values. Exocellular acid phosphatase, lipase, proteinase, hyaluronate lyase and haemolysin in culture filtrates were measured and the lethality of filtrates was determined in mice. The tampon materials had different effects on the levels of exocellular products. Cotton and carboxy-methyl cellulose cotton materials reduced the levels of all of the activities tested. The activities of the other enzymes were reduced or increased, depending on which material was present. All materials reduced both haemolytic activity and lethality of the culture filtrates. The in-vitro data suggest an extremely complex interaction between tampon materials and S. aureus.

Intergeneric and intrageneric inhibition between strains of Propionibacterium acnes and micrococcaceae, particularly Staphylococcus epidermidis, isolated from normal skin and acne lesions.

Two hundred and forty-one strains or resident skin bacteria comprising 93 isolates of Propionob acterium acnes and 148 of Micrococcaceae derived from 36 acne patients and 8 control subjects were screened for their ability to inhibit 32 indicator strains, including 20 strains of P. acnes and 12 strains of Staphylococcus epidermidis derived from patients with all grades of acne and from normal skin. Fifty-three strains (22%) showed some activity against at least one indicator strain. Both broad- and narrow-spectrum inhibition was detected. Inhibitory isolates of P. acnes outnumbered inhibitory Micrococcaceae by four to one. There was a low frequency of inhibition of S. epidermidis by Micrococcaceae (2.7%) and by P. acnes (1.1%) and a higher frequency of inhibition of P. acnes by Micrococcaceae (9.5%) and by P. acnes (40.8%). Furthermore, 81.8% of the subjects sampled possessed strains inhibitory to P. acnes. The significance of this finding is, as yet, unknown. No difference in the prevalence of active strains in normal (20%) and acne (22.5%) skin was detected. These findings suggest that the possession of inhibitory strains and conversely the possession of sensitive strains does not predispose to acne.

Is acne an infection of blocked pilosebaceous follicles? Implications for antimicrobial treatment.

A model is proposed which is based on the assumption that acne is due to infection of functionally blocked pilosebaceous follicles by propionibacteria. Noninflamed lesions, which are first visible during the adrenarche in acne-prone individuals, do not contain propionibacteria. Comedogenesis appears to be independent of bacterial infection and may be driven by high levels of bioactive interleukin-1 alpha derived from ductal hyperkeratinocytes. The stimulus which triggers interleukin-1 alpha production is unknown. Formalin killed Propionibacterium acnes failed to stimulate production of the cytokine by cultured human keratinocytes in vitro. Inflamed lesions are thought to arise from microcomedones, but the initiating events are unknown. Evidence that propionibacteria are involved in the generation of inflammatory lesions is inconclusive. The cellular infiltrate is consistent with a type IV hypersensitivity response to one or more persistent lesional antigens, not necessarily bacterial. The potent adjuvant activity of P. acnes would up-regulate the immune response to any antigen which came into contact with the mononuclear cell infiltrate. Antibiotics are widely used in the treatment of acne, and their effects in selecting a predominantly resistant commensal population are well recognized. Although they reduce numbers of propionibacteria on the skin, other modes of action may contribute to or explain their therapeutic efficacy. At a time when there is global concern that antibiotic resistance rates in common bacterial pathogens may threaten our future ability to control bacterial infections, practices which promote the spread of antibiotic-resistant bacteria must be fully justified. A thorough reappraisal of the role of propionibacteria in acne is overdue. It is likely that further experimental work is needed to confirm or refute that P. acnes is aptly named.

Minocycline for acne vulgaris: efficacy and safety.

BACKGROUND: Minocycline is a tetracycline antibiotic that is commonly used in the treatment of moderate to severe acne vulgaris. Although it is more convenient for patients to take than first-generation tetracyclines, as it only needs to be taken once or twice a day and can be taken with food, it is more expensive. Concerns have also been expressed over its safety following the deaths of two patients taking the drug. There is a lack of consensus among dermatologists over the relative risks and benefits of minocycline. As most acne prescribing is undertaken by general practitioners, it is important that guidelines issued to them are based on the best available evidence rather than personal judgements. OBJECTIVES: To collate and evaluate the evidence on the clinical efficacy of minocycline in the treatment of inflammatory acne vulgaris. Specific objectives were to compare the efficacy of minocycline with other drug treatments for acne and to collate information on the incidence of adverse drug reactions. SEARCH STRATEGY: Randomised controlled trials (RCTs) of minocycline for acne vulgaris were identified by searching the following electronic databases; MEDLINE, EMBASE, Biosis, Biological Abstracts, International Pharmaceutical Abstracts, Cochrane Skin Group's Trial Register, Theses Online, BIDS ISI Science Citation Index and Bids Index to Scientific and Technical Proceedings. Other strategies used were scanning the references of articles retrieved, hand-searching of major dermatology journals and personal communication with trialists and drug companies. SELECTION CRITERIA: To be eligible for the review, studies had to be RCTs comparing the efficacy of minocycline at any dose to active or placebo control, in subjects with inflammatory acne vulgaris. Diagnoses of papulo-pustular, polymorphic and nodular acne were also accepted. Trials were not excluded on the basis of language. DATA COLLECTION AND ANALYSIS: 27 randomised controlled trials met the inclusion criteria and were included in this review. The comparators used were placebo (2 studies), oxytetracycline (1), tetracycline (6), doxycycline (7), lymecycline (2), topical clindamycin (3), topical erythromycin/zinc (1), cyproterone acetate/ ethinyloestradiol (1), oral isotretinoin (2), topical fusidic acid (1) and there was one dose response study. One study is ongoing and it remains to be clarified whether one further study is a RCT. Major outcome measures used in the trials included lesion counts, acne grades/severity scores, doctors' and patients' global assessments, adverse drug reactions and drop out rates. The quality of each study was assessed independently by two assessors and an effect size calculated where possible. MAIN RESULTS: The trials were generally small and of poor quality and in many cases the published reports were inadequate for our purpose. Pooling of the studies was not attempted due to the lack of common outcome measures and endpoints and the unavailability of some primary data. Although minocycline was shown to be an effective treatment for acne vulgaris, in only two studies was it found to be superior to other tetracyclines. Both of these were conducted under open conditions and had serious methodological problems. A third study showed it to be more effective than 2% fusidic acid, applied topically, against inflammatory lesions in mild to moderate acne. Differences in the way adverse drug reactions were identified could have accounted for the wide variation between studies in numbers of events reported. This meant that no overall evaluation could be made of incidence rates of adverse events associated with minocycline therapy. No RCT evidence was found to support the benefits of minocycline in acne resistant to other therapies and the dose response has only been evaluated up to eight weeks of therapy. (ABSTRACT TRUNCATED)