Paromomycin (PA), a very hydrophilic antibiotic, has been tested as an alternative topical treatment against cutaneous leishmaniasis (CL). Although this treatment has shown promising results, it has not been successful in accelerating the recovery in most cases. This could be attributed to the low skin penetration of PA. Liposomal formulations usually provide sustained and enhanced drug levels in skin. The aim of this study was to prepare liposomal formulations containing PA and to investigate their potential as topical delivery systems of this antileishmanial. Large multilamellar vesicles (MLVs) were prepared by conventional solvent evaporation method. Large unilamellar vesicles (LUVs) were prepared by reverse-phase evaporation method. The lipids used were soybean phosphatidylcholine (PC) and PC:cholesterol (CH) (molar ratio 1:1). The skin permeation experiments across stripped and normal hairless mice skin were performed in modified Franz diffusion cells. The PA entrapment in LUV liposomes (20.4 +/- 2.2%) was higher than that observed for MLV liposomes (7.5 +/- 0.9%). Drug entrapment was 41.9 +/- 6.2% and 27.2 +/- 2.4% for PC and PC:CH LUV, respectively. The skin permeation was 1.55 +/- 0.31%, 1.29 +/- 0.40%, 0.20 +/- 0.08%, and 0.50 +/- 0.19% for PC LUV, PC:CH LUV, empty LUV +/- PA and aqueous solution, respectively. Controlled topical delivery, across stripped skin, was observed for PA entrapped in LUV liposomes.

What is known and objective Polymyxins were widely used until the 1960s; however, they fell into disfavour owing to their toxicity. The subsequent growth of infections caused by multidrug-resistant Gram-negative bacteria has led to renewed use of this class of antimicrobials in clinical practice. Acquired skin hyperpigmentation (SH) following intravenous polymyxin B treatment has been previously reported, but little is known about its pathogenesis, clinical course and treatment. To improve understanding of these issues, we conducted a prospective study of adult patients receiving intravenous polymyxin B treatment. Methods Patients receiving intravenous polymyxin B treatment were followed throughout the course of treatment. Clinical, dermatoscopic, histologic and immunohistochemical skin properties of patients who presented with SH were studied. Results and discussion Skin hyperpigmentation was noted in 8% of patients (n=20/249); however, clinical, dermatoscopic, histologic and immunohistochemical examinations were performed only in three patients for whom the consent of relatives was obtained. Histologic and immunohistochemical findings showed an abundant melanocyte-pigmented dendritic network. Langerhans cells' hyperplasia and dermal IL-6 overexpression were also found, presumably for an inflammatory process due to polymyxin B use. As polymyxin B causes the release of histamine, which is known for its melanogenic effect, it is possible that skin darkening is associated with this inflammatory mediator. What is new These clinical and dermatoscopic findings contribute to a better understanding of how the pigmentary reaction manifests following intravenous polymyxin B treatment. Conclusion We concluded that hyperpigmentation due to intravenous polymyxin B treatment is associated with an inflammatory process and subsequent melanocyte activation. Although the pigmentary disorder neither influences the outcome of the therapy nor warrants discontinuation of treatment, it nevertheless considerably affects the patient's quality of life.

This work aimed to develop nanoemulsions (NE) containing cholesterol and Amphotericin B (AmB) evaluating the influence of a lipophilic amine (stearylamine; STE) on drug encapsulation efficiency (EE), cytotoxicity on macrophages and in vitro antileishmanial activity. The EE of AmB in NE was nearly 100% regardless of STE concentration. Stability studies showed that AmB-loaded NE with or without STE were stable revealing that AmB content and EE remained constant after 180days. In significant contrast, the EE for AmB in NE without cholesterol drastically decreased showing that this co-surfactant significantly improved the retention of drug in NE. The electronic absorption and circular dichroism (CD) data revealed that the signal characteristic of self-associated free AmB, the most toxic form to the host cells, was virtually absent in the spectra of AmB-loaded NE. In agreement, NE-induced toxicity toward macrophages was significantly lower than that observed for the conventional AmB. STE enhanced both cytotoxicity and the activity against intracellular amastigotes of AmB-loaded NE. However, selectivity index values for AmB-loaded NE were considerably higher than that observed for conventional AmB. AmB-loaded and cholesterol-stabilized NE constitutes an attractive alternative for the treatment of leishmaniasis.

The present study aimed to evaluate the potential of liposomes loaded with paromomycin (PA), an aminoglycoside antibiotic associated with poor skin penetration, for the topical treatment of cutaneous leishmaniasis (CL). Fluid liposomes were prepared and characterized for particle size, zeta potential, and drug entrapment. Permeation studies were performed with two in vitro models: intact and stripped skin. The antileishmanial activity of free and liposomal PA was evaluated in BALB/c mice infected by Leishmania (L.) major. Drug entrapment ranged from 10 to 14%, and the type of vesicle had little influence on this parameter. Particle size and polydispersity index of the vesicles composed by phosphatidylcholine (PC) and PC/cholesterol (Chol) ranged from of 516 to 362 nm and 0.7 to 0.4, respectively. PA permeation across intact skin was low, regardless of the formulation tested, while drug penetration into skin (percent of the applied dose) from PC (7.2 +/- 0.2%) and PC/Chol (4.8 +/- 0.2%) liposomes was higher than solution (1.9 +/- 0.1%). PA-loaded liposomes enhanced in vitro drug permeation across stripped skin and improved the in vivo antileishmanial activity in experimentally infected mice. Our findings suggest that the liposomes represent a promising alternative for the topical treatment of CL using PA.

Topical therapy is the first choice for the treatment of mild to moderate acne and all-trans retinoic acid is one of the most used drugs. The combination of retinoids and antimicrobials is an innovative approach for acne therapy. Recently, lauric acid, a saturated fatty acid, has shown strong antimicrobial activity against Propionibacterium acnes. However, topical application of retinoic acid is followed by high incidence of side-effects, including erythema and irritation. Solid lipid nanoparticles represent an alternative to overcome these side-effects. This work aims to develop solid lipid nanoparticles loaded with retinoic acid and lauric acid and evaluate their antibacterial activity. The influence of lipophilic stearylamine on the characteristics of solid lipid nanoparticles was investigated. Solid lipid nanoparticles were characterized for size, zeta potential, encapsulation efficiency, differential scanning calorimetry and X-ray diffraction. The in vitro inhibitory activity of retinoic acid-lauric acid-loaded solid lipid nanoparticles was evaluated against Propionibacterium acnes, Staphylococcus aureus and Staphylococcus epidermidis. High encapsulation efficiency was obtained at initial time (94 ± 7% and 100 ± 4% for retinoic acid and lauric acid, respectively) and it was demonstrated that lauric acid-loaded-solid lipid nanoparticles provided the incorporation of retinoic acid. However, the presence of stearylamine is necessary to ensure stability of encapsulation. Moreover, retinoic acid-lauric acid-loaded solid lipid nanoparticles showed growth inhibitory activity against Staphylococcus epidermidis, Propionibacterium acnes and Staphylococcus aureus, representing an interesting alternative for the topical therapy of acne vulgaris.

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Objectives All-trans retinoic acid (ATRA) is one of the most successful examples of differentiation agents and histone deacetylase inhibitors, such as tributyrin (TB), are known for their antitumor activity and potentiating action of drugs such as ATRA. Nanostructured lipid carriers (NLC) represent a promising alternative to the encapsulation of lipophilic drugs such as ATRA. This study aimed to develop, characterize, and evaluate the cytotoxicity of ATRA-TB-loaded nanostructured lipid carriers (NLC) for cancer treatment. Methods The influence of in situ formation of an ion pairing between ATRA and a lipophilic amine (benethamine; BNT) on the characteristics of NLC (size, zeta potential, encapsulation efficiency) was evaluated. Tributyrin (TB), a butyric acid donor, was used as a component of the lipid matrix. In vitro activity on cell viability and distribution of cell cycle phases were evaluated for MCF-7, MDA-MB-231, HL-60, and Jurkat cell lines. Results The presence of the amine significantly increased the encapsulation efficiency of ATRA in NLC. Inhibition of cell viability by TB-ATRA-loaded NLC was more pronounced than the free drug. Analysis of the distribution of cell cycle phases also showed increased activity for TB-ATRA-loaded NLC, with the clear effect of cell cycle arrest in G0/G1 phase transition. The presence of TB played an important role in the activity of the formulation. Conclusion Taken together, these findings suggest that TB-ATRA-loaded NLC represent a promising alternative to intravenous administration of ATRA in cancer treatment.