Topical Antibacterials in Dermatology

Breaking boundaries: the advancements in transdermal delivery of antibiotics

Transdermal drug delivery systems (TDDS) for antibiotics have seen significant advances in recent years that aimed to improve the efficacy and safety of these drugs. TDDS offer many advantages over other conventional delivery systems such as non-invasiveness, controlled-release pattern, avoidance of first-pass metabolism. The objective of this review is to provide an overview on the recent advances in the TDDS of different groups of antibiotics including β-lactams, tetracyclines, macrolides, and lincosamides, utilized for their effective delivery through the skin and to explore the challenges associated with this field. The majority of antibiotics do not have favorable properties for passive transdermal delivery. Thus, novel strategies have been employed to improve the delivery of antibiotics through the skin, such as the use of nanotechnology (nanoparticles, solid-lipid nanoparticles, nanoemulsions, vesicular carriers, and liposomes) or the physical enhancement techniques like microneedles and ultrasound. In conclusion, the transdermal delivery systems could be a promising method for delivering antibiotics that have the potential to improve patient outcomes and enhance the efficacy of drugs. Further research and development are still needed to explore the potential of delivering more antibiotic drugs by using various transdermal drug delivery approaches.

Amniotic membrane dressings for treatment of aplasia cutis in newborns

BACKGROUND

Aplasia cutis congenita (ACC) is a rare congenital skin defect characterized by a focal or extensive absence of the epidermis, dermis, and occasionally, subcutaneous tissue. When the wound caused by this defect is wide or deep, various treatments are used, including skin grafting. The amniotic membrane (AM) is a biological dressing that facilitates re-epithelialization as it contains mesenchymal cells and numerous growth factors.

OBJECTIVE

To report the efficacy of AM dressings in treating the skin defects of ACC.

METHOD

This study was conducted on five neonates diagnosed with ACC born between 2018 and 2022, referred to the Children's Medical Center in Tehran, Iran. AM dressings were applied on wounds larger than 1 cm2. The wounds were assessed weekly and, if required, an additional AM dressing was applied.

RESULTS

The skin defects gradually re-epithelialized after application of the AM. The complete healing process took around 3.5 weeks on average. No hypertrophic scarring was observed.

CONCLUSION

The application of AM dressing resulted in satisfactory cosmetic outcomes, with no hypertrophic scar formation. Complete healing occurred in all cases except one. The length of the hospital stay ranged from 2 to 6 weeks, depending on the size of the wound.

Attitudes, Beliefs, and Behaviors of Topical Antibiotic Prescribing among Primary Care Providers in Saudi Arabia: A Cross-Sectional Study

BACKGROUND

The World Health Organization (WHO) estimates that 20-50% of antibiotics are misused in society. In addition to the development of antimicrobial resistance, topical antibiotics have been associated with adverse effects such as allergic contact dermatitis (ACD) and inadequate wound healing. This study investigated the appropriateness of topical antibiotic prescriptions among primary care providers in Saudi Arabia.

METHODS

A cross-sectional survey was conducted among Saudi Arabian primary care providers (physicians (general, family, and internal medicine)) employed in governmental and non-governmental healthcare facilities (primary care centers and outpatient clinics).

RESULTS

In total, 222 participants were included in the analysis. A total of 73% agreed that inappropriate topical antibiotic use puts patients at risk, and 43% reported antibiotic resistance in daily practice. Many respondents lacked knowledge of the proper indications for topical antibiotics, and 66.2% attributed this to a lack of updated knowledge, while 45% blamed inadequate supervision.

CONCLUSION

Antibiotic prescription patterns deviated from the standards recommended by WHO. This calls for continuous review at all levels of healthcare, providing more physician education and ensuring that antibiotic therapy guidelines are easily accessible and effectively used to avoid the negative consequences of inappropriate antibiotic prescription.

Alginate and Chitosan-Based Hydrogel Enhance Antibacterial Agent Activity on Topical Application

Untreated topical infections can become chronic, posing serious health issues. Optimal skin adherence is crucial in addressing such infections. In this context, chitosan and alginate emerge as promising candidates for use as a foundation in the development of topical hydrogels. The aim of this review is to examine the literature on topical hydrogel formulations that use chitosan and alginate as foundations, specifically in the context of topical antibacterial agents. The research methodology involves a literature review by examining articles published in databases such as PubMed, Scopus, ScienceDirect, and Google Scholar. The keywords employed during the research were "Alginate", "Chitosan", "Hydrogel", and "Antibacterial". Chitosan and alginate serve as bases in topical hydrogels to deliver various active ingredients, particularly antibacterial agents, as indicated by the search results. Both have demonstrated significant antibacterial effectiveness, as evidenced by a reduction in bacterial colony counts and an increase in inhibition zones. This strongly supports the idea that chitosan and alginate could be used together to make topical hydrogels that kill bacteria that work well. In conclusion, chitosan and alginate-based hydrogels show great potential in treating bacterial infections on the skin surface. The incorporation of chitosan and alginate into hydrogel formulations aids in retaining antibacterial agents, allowing for their gradual release over an optimal period. Therefore, hydrogels specifically formulated with chitosan and alginate have the potential to serve as a solution to address challenges in the treatment of topical bacterial infections.

Perspectives on antimicrobial properties of Paulownia tomentosa Steud. fruit products in the control of Staphylococcus aureus infections

ETHNOPHARMACOLOGICAL RELEVANCE

Paulownia tomentosa Steud. (P. tomentosa) is a medium-sized tree traditionally used in Chinese folk medicine for the treatment of infectious diseases. It is a rich source of prenylated phenolic compounds that have been extensively studied for their promising biological activities.

AIM OF THE STUDY

Due to the increasing development of antibiotic resistance, our study investigated plant-derived natural products from the fruits of P. tomentosa that could control Staphylococcus aureus infections with novel targets/modes of action and reduce antimicrobial resistance.

MATERIALS AND METHODS

The ethanolic extract was fractionated and detected by liquid chromatography. The antistaphylococcal effects of the plant formulations were studied in detail in vitro by various biological methods, including microdilution methods for minimum inhibitory concentration (MIC), the checkerboard titration technique for synergy assay, fluorescence measurements for membrane disruption experiments, autoinducer-2-mediated bioassay for quorum sensing inhibition, and counting of colony-forming units for relative adhesion. Morphology was examined by transmission electron microscopy.

RESULTS

Total ethanolic extract and chloroform fraction showed MICs of 128 and 32 μg/mL, respectively. Diplacol, diplacone, and 3'-O-methyl-5'-hydroxydiplacone inhibited S. aureus growth in the range of 8-16 μg/mL. Synergistic potential was shown in combination with mupirocin and fusidic acid. The ethanolic extract and the chloroform fraction destroyed the cell membranes by 91.61% and 79.46%, respectively, while the pure compounds were less active. The ethanolic extract and the pure compounds reduced the number of adhered cells to 47.33-10.26% compared to the untreated control. All tested plant formulations, except diplacone, inhibited quorum sensing of S. aureus. Transmission electron microscopy showed deformation of S. aureus cells.

CONCLUSIONS

The products from the fruit of P. tomentosa showed antimicrobial properties against S. aureus alone and in combination with antibiotics. By affecting intracellular targets, geranylated flavonoids proposed novel approaches in the control of staphylococcal infections.

Emerging Medical Therapies in Rosacea: A Narrative Review

Rosacea is a chronic inflammatory disease with a multifactorial pathogenesis. The wide spectrum of clinical phenotypes, including erythema, telangiectasia, inflammatory papules and pustules, and phyma, demand an individualized approach to treatment. This narrative review offers an updated reference for rosacea management by covering the latest developments in both topical and systemic treatments, including data from newly approved therapies, updates to current treatment modalities and ongoing clinical trials. Although use of benzoyl peroxide as a treatment for rosacea has typically been limited due to irritation, the improved tolerability due to microencapsulation of benzoyl peroxide 5% cream provides a new therapeutic option for patients with rosacea. Minocycline foam and topical ivermectin cream add to our armamentarium of treatment options, particularly for inflammatory papules and pustules. Sarecycline has a narrower spectrum of antibacterial activity, which might reduce the development of antibiotic resistance and disruption of the microbiome compared to other oral antibiotics. Brimonidine gel and oxymetazoline cream provide topical options for redness and flushing. There is emerging evidence about the role of hydroxychloroquine and intradermal botulinum toxin A, which may improve rosacea through their effects on mast cells. The clinical trials pipeline includes agents with a variety of mechanisms, including mast cell stabilization, antimicrobial, anti-inflammatory, and vasoconstrictive effects. However, the clinical pipeline for rosacea appears limited, and there remain important unmet needs for patients with more recalcitrant rosacea or phymatous disease. In addition, there is a need for comparative effectiveness studies to identify the highest value treatment approaches for patients with rosacea.

Efficacy and safety of microencapsulated benzoyl peroxide and microencapsulated tretinoin for the treatment of acne vulgaris: Results from two phase 3 double-blind, randomized, vehicle-controlled studies

BACKGROUND

Benzoyl peroxide and tretinoin are commonly prescribed acne treatments. Historically, they have been difficult to combine in a single formulation due to chemical instability, and both medications are potentially irritating. Microencapsulation helps overcome these challenges.

OBJECTIVE

Examine efficacy, safety, and tolerability of encapsulated BPO/encapsulated tretinoin (E-BPO/T) cream, 3%/0.1%.

METHODS

Subjects ≥9 years old with moderate to severe acne were enrolled in 2 multicenter, double-blind, vehicle-controlled, parallel trials and randomized (2:1) to 12 weeks of once-daily E-BPO/T (n = 571) or vehicle cream (n = 287).

RESULTS

E-BPO/T was significantly superior to vehicle in both studies, with more subjects achieving IGA success with E-BPO/T (38.5%/25.4%) versus vehicle (11.5%/14.7%; P < .001/P = .017). The change from baseline in inflammatory lesion count for E-BPO/T was -21.6 versus -14.8 for vehicle (P < .001) in study 1 and -16.2 versus -14.1 (P = .018) in study 2. The changes from baseline in noninflammatory lesions for E-BPO/T were -29.7 versus -19.8 for vehicle (P < .001) and -24.2 and -17.4 (P < .001) in studies 1 and 2, respectively. E-BPO/T was well tolerated in both studies.

LIMITATIONS

Long-term data are not available.

CONCLUSION

E-BPO/T provided statistically significant and clinically relevant improvements in IGA and inflammatory and noninflammatory lesion counts and was well tolerated in subjects with moderate to severe acne.

Polysaccharide-based hydrogel promotes skin wound repair and research progress on its repair mechanism

Polysaccharides, being a natural, active, and biodegradable polymer, have garnered significant attention due to their exceptional properties. These properties make them ideal for creating multifunctional hydrogels that can be used as wound dressings for skin injuries. Polysaccharide hydrogel has the ability to both simulate the natural extracellular matrix, promote cell proliferation, and provide a suitable environment for wound healing while protecting it from bacterial invasion. Polysaccharide hydrogels offer a promising solution for repairing damaged skin. This review provides an overview of the mechanisms involved in skin damage repair and emphasizes the potential of polysaccharide hydrogels in this regard. For different skin injuries, polysaccharide hydrogels can play a role in promoting wound healing. However, we still need to conduct more research on polysaccharide hydrogels to provide more possibilities for skin damage repair.

Efficacy and Safety of Microencapsulated Benzoyl Peroxide Cream, 5%, in Rosacea: Results From Two Phase III, Randomized, Vehicle-Controlled Trials

Objective

A new formulation of benzoyl peroxide (E-BPO cream, 5%) entraps benzoyl peroxide (BPO) in silica microcapsules. This study assesses the efficacy, safety, and tolerability of E-BPO cream, 5%, in rosacea in two Phase III clinical trials.

Methods

In two 12-week, randomized, double-blind, vehicle cream-controlled Phase III trials, 733 subjects at least 18 years old with moderate to severe rosacea were randomized (2:1) to once-daily E-BPO cream, 5%, or vehicle.

Results

In Study 1, the proportion of subjects achieving IGA clear/almost clear at Week 12 was 43.5 percent for E-BPO cream, 5%, and 16.1 percent for vehicle. In Study 2, the respective values were 50.1 percent and 25.9 percent. In Study 1, the decrease in lesion count from baseline to Week 12 was -17.4 for E-BPO cream, 5%, versus -9.5 for vehicle. In Study 2, the respective values were -20.3 and -13.3 (all P<0.001). The difference was also significant at Week 2. There were no treatment-related serious adverse events; 1.4 percent of subjects (1.8% E-BPO cream, 5%, 0.4% vehicle) discontinued due to adverse events. Assessed local tolerability was found to be similar among subjects in both E-BPO and vehicle.

E-BPO was not compared with unencapsulated BPO.

Conclusion

E-BPO is an effective and well tolerated treatment for rosacea. Clinicaltrials.gov Identifiers: NCT03564119, NCT03448939.

Usage of Antimicrobials in Equine Veterinary Practice in Denmark - A Case-Based Survey

Horses may be carriers of important resistant bacteria like methicillin-resistant staphylococci. Such bacteria can potentially threaten both equine and public health, but little is known about predisposing factors like antimicrobial usage patterns in equines. Objectives of this study were to investigate the antimicrobial usage practices by Danish equine practitioners as well as factors impacting usage. A total of 103 equine practitioners filled in an online questionnaire. When asked to explain their typical treatment of six clinical case scenarios, only 1% and 7% of respondents prescribed systemic antimicrobials for a cough and pastern dermatitis, respectively. More frequent usage was reported for diarrhoea (43%), extraction of a cracked tooth (44%), strangles (56%), and superficial wound near a joint (72%). Among the antibiotics indicated for treatment, enrofloxacin was the only critically important antimicrobial agent reported by two respondents. Thirty-eight (36%) respondents worked in practices with antimicrobial protocols. When asked to prioritize the most important factor influencing prescribing habits, bacterial culture (47%) and antimicrobial protocols (45%) were selected far more often than the owner´s economy (5%) and expectations (4%). Veterinarians reported limitations such as the availability of only one oral antibiotic (sulphadiazine/trimethoprim), and a need for clearer treatment guidelines. In conclusion, the study highlighted important aspects regarding antimicrobial usage among equine practitioners. Antimicrobial protocols and pre- and post-graduate education on prudent antimicrobial usage are recommended.

No country for old antibiotics! Antimicrobial peptides (AMPs) as next-generation treatment for skin and soft tissue infection

In recent years, the unprecedented rise of bacterial antibiotic resistance together with the lack of adequate therapies have made the treatment of skin infections and chronic wounds challenging, urging the scientific community to focus on the development of new and more efficient treatment strategies. In this context, there is a growing interest in the use of natural molecules with antimicrobial features, capable of supporting wound healing i.e., antimicrobial peptides (AMPs), for the treatment of skin and soft tissue infections. In this review, we give a short overview of the bacterial skin infections as well as some of the classic treatments used for topical application. We then summarize the AMPs classes, stressing the importance of the appropriate selection of the peptides based on their characteristics and physicochemical properties in order to maximize the antibacterial efficacy of the therapeutic systems against multi-drug resistant pathogens. Additionally, the present paper provides a comprehensive and rigorous assessment of the latest clinical trials investigating the efficacy of AMPs in the treatment of skin and soft tissue infections, highlighting the relevant outcomes. Seeking to obtain novel and improved compounds with synergistic activity, while also decreasing some of the known side effects of AMPs, we present two employed strategies using AMPs: (i) AMPs-conjugated nanosystems for systemic and topical drug delivery systems and (ii) antibiotics-peptide conjugates as a strategy to overcome antibiotics resistance. Finally, an important property of some of the AMPs used in wound treatment is highlighted: their ability to help in wound healing by generally promoting cell proliferation and migration, and in some cases re-epithelialization and angiogenesis among others. Thus, as the pursuit of improvement is an ongoing effort, this work presents the advances made in the treatment of skin and soft tissue infections along with their advantages and limitations, while the still remaining challenges are addressed by providing future prospects and strategies to overcome them.

Skin Pigmentation Types, Causes and Treatment-A Review

Human skin pigmentation and melanin synthesis are incredibly variable, and are impacted by genetics, UV exposure, and some drugs. Patients' physical appearance, psychological health, and social functioning are all impacted by a sizable number of skin conditions that cause pigmentary abnormalities. Hyperpigmentation, where pigment appears to overflow, and hypopigmentation, where pigment is reduced, are the two major classifications of skin pigmentation. Albinism, melasma, vitiligo, Addison's disease, and post-inflammatory hyperpigmentation, which can be brought on by eczema, acne vulgaris, and drug interactions, are the most common skin pigmentation disorders in clinical practice. Anti-inflammatory medications, antioxidants, and medications that inhibit tyrosinase, which prevents the production of melanin, are all possible treatments for pigmentation problems. Skin pigmentation can be treated orally and topically with medications, herbal remedies, and cosmetic products, but a doctor should always be consulted before beginning any new medicine or treatment plan. This review article explores the numerous types of pigmentation problems, their causes, and treatments, as well as the 25 plants, 4 marine species, and 17 topical and oral medications now on the market that have been clinically tested to treat skin diseases.

Minor Skin Injuries at School: The Role of the School Nurse

School nurses routinely provide simple wound care for minor injuries in the school health office. Simple wound care is centered on the principles of moist wound care and only requires a few supplies to be on hand. This article outlines the steps for simple wound care for minor abrasions, cuts, blisters, and burns. Recommendations for referral of more complicated wounds are also provided. Student encounters for minor wound care can also be used by school nurses to provide education on first aid and to teach students, parents, and caregivers about infection prevention and control of the wound.

Antibacterial and Anti-Acne Activity of Benzoyl Peroxide Nanoparticles Incorporated in Lemongrass Oil Nanoemulgel

Purpose: The goal of this study was to make Benzoyl Peroxide (BPO) nanoemulgel to improve its ability to kill bacteria. BPO has trouble getting into the skin, being absorbed by the skin, staying stable, and being spread out. Methods: A BPO nanoemulgel formulation was prepared by combining BPO nanoemulsion with Carbopol hydrogel. The drug was tested for solubility in various oils and surfactants in order to select the best oil and surfactant for the drug, and then the drug nanoemulsion formulation was prepared using a self-nano-emulsifying technique with Tween 80, Span 80, and lemongrass oil. The drug nanoemulgel was looked at in terms of its particle size, polydispersity index (PDI), rheological behavior, drug release, and antimicrobial activity. Results: Based on the solubility test results, lemongrass oil was the best solubilizing oil for drugs, while Tween 80 and Span 80 demonstrated the highest solubilizing ability for drugs among the surfactants. The optimum self-nano-emulsifying formulation had particle sizes of less than 200 nm and a PDI of close to zero. The results showed that incorporating the SNEDDS formulation of the drug with Carbopol at various concentrations did not cause a significant change in the particle size and PDI of the drug. The zeta potential results for drug nanoemulgel were negative, with more than 30 mV. All nanoemulgel formulations exhibited pseudo-plastic behavior, with 0.4% Carbopol exhibiting the highest release pattern. The drug nanoemulgel formulation worked better against bacteria and acne than the product on the market. Conclusion: Nanoemulgel is a promising way to deliver BPO because it makes the drug more stable and increases its ability to kill bacteria.

Topical Antibiotic Treatment in Dermatology

Many indications in dermatology can be effectively managed with topical antibiotics, including acne vulgaris, wound infections, secondarily infected dermatitis, and impetigo. Dermatologists must be familiar with the wide spectrum of topical antibiotics available, including indications, mechanisms of action, adverse events, and spectra of activity. Dermatologists must also keep antibiotic resistance in mind when utilizing these medications. Due to the widespread use of topical antibiotics and their importance in dermatology, a literature review was performed using a systematic search of PubMed and Google Scholar with the terms topical antibiotics, skin infections, dermatology, antimicrobials, and inflammatory dermatoses to identify English-language articles published between 1965-2022 from any country. Relevant publications were manually reviewed for additional content. The following literature review will summarize the common topical antibiotics used in dermatology.

Polysaccharide-based hydrogels: New insights and futuristic prospects in wound healing

Polysaccharides elicit enormous and promising applications due to their extensive obtainability, innocuousness, and biodegradability. Various outstanding features of polysaccharides can be employed to fabricate biomimetic and multifunctional hydrogels as efficient wound dressings. These hydrogels mimic the natural extracellular matrix and also boost the proliferation of cells. Owing to distinctive architectures and abundance of functional groups, polysaccharide-derived hydrogels have exceptional physicochemical properties and unique therapeutic interventions. Hydrogels designed using polysaccharides can effectively safeguard wounds from bacterial attack. This review includes wound physiology and emphasises on numerous polysaccharide-based hydrogels for wound repair applications. Polysaccharide hydrogels for different wound types and diverse therapeutic agents loaded in hydrogels for wound repair with recent patents are portrayed in the current manuscript, debating the potential of fascinating hydrogels for effective wound healing. More research is required to engineer multifaceted advanced polysaccharide hydrogels with tuneable and adjustable properties to attain huge potential in wound healing.

Repurposing Disulfiram as an Antimicrobial Agent in Topical Infections

Antimicrobial drugs applied topically offer several advantages. However, the widespread use of antibiotics has led to increasing antimicrobial resistance. One interesting approach in the drug discovery process is drug repurposing. Disulfiram, which was originally approved as an anti-alcoholism drug, offers an attractive alternative to treat topical multidrug resistance bacteria in skin human infections. This study aimed to evaluate the biopharmaceutical characteristics of the drug and the effects arising from its topical application in detail. Microdilution susceptibility testing showed antibacterial activity against Gram-positive bacteria Staphylococcus aureus and Streptococcus pyogenes. Dermal absorption revealed no permeation in pig skin. The quantification of the drug retained in pig skin demonstrated concentrations in the stratum corneum and epidermis, enough to treat skin infections. Moreover, in vitro cytotoxicity and micro-array analyses were performed to better understand the mechanism of action and revealed the importance of the drug as a metal ion chelator. Together, our findings suggest that disulfiram has the potential to be repurposed as an effective antibiotic to treat superficial human skin infections.

Evaluation of the Preliminary Safety, Tolerability and Colonisation Efficacy of Topical Probiotic Formulations Containing Micrococcus luteus Q24 in Healthy Human Adults

Probiotics developed for topical applications in humans have the potential to beneficially modulate microbial imbalances on the skin surface and thereby improve skin health. This study was conducted to determine whether topical formulations containing the human skin commensal Micrococcus luteus strain Q24 (BLIS Q24) are safe, tolerable and efficacious when used by healthy human subjects. M. luteus Q24 was assessed in vitro for haemolytic activity and its antibiotic susceptibility profile. Formulations of strain Q24 were evaluated for the preliminary safety and tolerability in healthy human participants. Forty-seven adults were randomly assigned to four single-site, single-blind randomised placebo or baseline controlled or active-controlled trials. Skin swab samples were collected for differential viable counts to monitor levels of probiotic colonisation. M. luteus Q24 was found to be non-haemolytic and susceptible to commonly used antibiotics. The M. luteus Q24 formulations were safe and tolerable and >90% of the participants reported improvements from baseline in the appearance (e.g., radiance and hydration) of their treated skin. Additionally, participants observed a reduction in pore size, skin clarity and enhanced skin softness. No adverse effects were reported. A dose-related significant increase was observed in the levels of M. luteus Q24 isolated from skin swabs of the probiotic-treated subjects. Placebo-controlled trials in human subjects involving the topical application of different doses of M. luteus Q24 formulations were supportive of the safety, tolerability and efficacy of probiotic M. luteus Q24. Self-reported skin health assessments by the subjects indicated that M. luteus Q24 has good potential as a probiotic for improving skin health quality.

Adverse-Event Reports in Over-the-Counter Topical Acne Drug Products Containing Benzoyl Peroxide from a Specific Pharmaceutical Company in the USA

Benzoyl peroxide (BPO) has been used extensively in dermatology, often for the treatment of acne vulgaris. In a 20-year period, dermatologists in the United States used over-the-counter BPO more than 13 million times. However, skin irritation and other adverse events (AEs) are associated with the use of BPO. AEs associated with BPO were identified using the Galderma pharmacovigilance system, which collects AE reports from multiple sources. Over approximately 20 years, 558 AE reports were collected from the database, ranging from application site reactions to systemic hypersensitivity reactions, resulting in a reporting rate of under 1%. These data show that the risk of OTC topical acne drug products containing BPO is low.

Rapid In Situ Deposition of Iron-Chelated Polydopamine Coating on the Polyacrylamide Hydrogel Dressings for Combined Photothermal and Chemodynamic Therapy of Skin Wound Infection

Pathogenic bacterial infections of skin wounds have caused a significant threat to clinical treatment and human life safety. Here, we develop a bactericidal hydrogel dressing consisting of a polyacrylamide (PAM) hydrogel framework with in situ surface-deposition of iron-dopped polydopamine (FePDA). The prepared hydrogel dressing (FePDA-PAM) has a compact surface, good tensile strength, and excellent elastic recovery ability. The introduction of Fe3+ ions improve the photothermal therapy (PTT) efficiency of the PDA and endow the hydrogel dressing with chemodynamic therapy (CDT) properties. In vitro experiments show that the antibacterial effect of FePDA-PAM hydrogel on Staphylococcus aureus reach nearly 100% under the combined action of H2O2 and 808 nm near-infrared (NIR) laser, indicating an excellent combined antibacterial property of PTT and CDT. Furthermore, the FePDA-PAM + H2O2 + NIR treatment group in the in vivo antibacterial experiments displays lowest relative wound area and optimal wound healing within 5 days of treatment, thereby indicating the intensive skin wound disinfection. To summarize, the FePDA-PAM hydrogel has simple preparation and good biosafety. It may serve as a potential wound dressing for the combined PTT/CDT dual-mode antibacterial therapy.

Tea Tree Oil Nanoemulsion-Based Hydrogel Vehicle for Enhancing Topical Delivery of Neomycin

The present investigation aims to improve the antimicrobial influence of certain antibacterial drugs, namely, neomycin (NEO), exploiting the benefits of natural oils such as tea tree oil (TTO). Therefore, a distinctive nanolipid formulation, namely, a nanoemulsion (NE), was developed using a Central Composite Factorial Design (CCD) approach depending on the amount of TTO and tween 80 as surfactant. The optimized NEO-NE formula exhibiting minimum globular size and maximum in vitro release was selected. For efficient topical delivery, NEO-NE was incorporated into a pre-formulated hydrogel. The developed NEO-NE-hydrogel was characterized by its physical characteristics such as pH, viscosity, and spreadability. Next, it was tested for stability under different conditions for 3 months. Ultimately, an irritation test was conducted followed by an antibacterial examination. The preparation demonstrated acceptable properties to be successfully applied topically. It showed non-significant changes in stability in both conditions up to 3 months storage when compared to a fresh preparation. It exhibited no irritation when applied on hairless animal skin. Finally, TTO revealed a good inhibition for the bacterial growth that could improve the influence of NEO antibacterial activity, indicating the efficiency of NE containing NEO prepared with TTO to be a promising antibacterial nanocarrier.