Nanoparticulated Systems Based on Natural Polymers Loaded with Miconazole Nitrate and Lidocaine for the Treatment of Topical Candidiasis.

People with weakened immune systems are at risk of developing candidiasis which is a fungal infection caused by several species of Candida genus. In this work, polymeric nanoparticles containing miconazole nitrate and the anesthetic lidocaine clorhydrate were developed. Miconazole was chosen as a typical drug to treat buccopharyngeal candidiasis whereas lidocaine may be useful in the management of the pain burning, and pruritus caused by the infection. Nanoparticles were synthesized using chitosan and gelatin at different ratios ranging from 10:90 to 90:10. The nano-systems presented nanometric size (between 80 and 300 nm in water; with polydispersion index ranging from 0.120 to 0.596), and positive Z potential (between 20.11 and 37.12 mV). The determined encapsulation efficiency ranges from 65 to 99% or 34 to 91% for miconazole nitrate and lidocaine clorhydrate, respectively. X-ray diffraction and DSC analysis suggested that both drugs were in amorphous state in the nanoparticles. Finally, the systems fitted best the Korsmeyer-Peppas model showing that the release from the nanoparticles was through diffusion allowing a sustained release of both drugs and prolonged the activity of miconazole nitrate over time against Candida albicans for at least 24 h.

Ligand and structure-based virtual screening applied to the SARS-CoV-2 main protease: an in silico repurposing study.

Aim: The identification of drugs for the coronavirus disease-19 pandemic remains urgent. In this manner, drug repurposing is a suitable strategy, saving resources and time normally spent during regular drug discovery frameworks. Essential for viral replication, the main protease has been explored as a promising target for the drug discovery process. Materials & methods: Our virtual screening pipeline relies on the known 3D properties of noncovalent ligands and features of crystalized complexes, applying consensus analyses in each step. Results: Two oral (bedaquiline and glibenclamide) and one buccal drug (miconazole) presented 3D similarity to known ligands, reasonable predicted binding modes and micromolar predicted binding affinity values. Conclusion: We identified three approved drugs as promising inhibitors of the main viral protease and suggested design insights for future studies for development of novel selective inhibitors.

Development, characterization, and in vitro-in vivo evaluation of polymeric nanoparticles containing miconazole and farnesol for treatment of vulvovaginal candidiasis.

Vulvovaginal candidiasis (VVC) is caused mainly by the opportunistic fungus Candida albicans, and its yeast to hyphae transition is considered a major virulence factor. Farnesol is a molecule that inhibits yeast to hyphae transition. The increased incidence of VVC has influenced a need for developing new therapeutic strategies. The objective was to develop a mucoadhesive nanostructured system composed of miconazole and farnesol co-encapsulated within chitosan nanoparticles. The miconazole presented a minimal inhibitory concentration (MIC) of 1 µg/ml against C. albicans. The farnesol was capable of inhibiting yeast to hyphae transition at levels greater or equal to 300 µM. The combination of miconazole and farnesol showed no change in miconazole MIC. Chitosan nanoparticles containing miconazole and farnesol were prepared by ionic gelation and showed favorable characteristics for use on mucous membranes. They showed size variation and polydispersion index (PDI) after 30 days, but the efficiency of drug encapsulation was maintained. Regarding toxicity in cultured fibroblasts (BALB/c 3T3) the nanoparticles were considered nontoxic. The nanoparticles showed antifungal activity against the C. albicans strain used with MICs of 2.5 µg/ml and 2 µg/ml for nanoparticles containing miconazole or miconazole/farnesol, respectively. Nanoparticles containing farnesol inhibited yeast to hyphae transition at concentrations greater than or equal to 240 µM. The in vivo antifungal activity was assessed in the murine model for VVC. The results suggested that chitosan nanoparticles containing miconazole and farnesol were effective at inhibiting fungal proliferation. Additionally, chitosan nanoparticles containing farnesol were capable of decreasing the pathogenicity of infection, demonstrated through the absence of inflammation.

Composite Microparticles Based on Natural Mucoadhesive Polymers with Promising Structural Properties to Protect and Improve the Antifungal Activity of Miconazole Nitrate.

Oropharyngeal candidiasis is a recurrent oral infection caused by Candida species. Gel formulation containing miconazole nitrate is the most common approach for treating oral candidiasis. However, traditional oral topical antifungal therapies have many limitations, including short contact time with the oral mucosa and the necessity to administrate various doses per day. Thus, the aim of this work was to formulate composited microparticulated systems based on combinations of mucoadhesive cationic, anionic, and nonionic polymers that could protect and modify the drug release rate and therefore avoid a fast dilution of the drug by saliva. Microparticulated systems were prepared by the spray drying method employing chitosan, gelatin, and hydroxypropyl methylcellulose. The morphology of the systems was investigated by scanning electron microscopy; drug crystallinity was studied by X-ray, while interactions between polymers were analyzed by infrared spectroscopy. Drug release and halo zone test were employed to analyze the release and activity of the systems loaded with miconazole against Candida albicans cultures. The most appropriate microparticulated system was the one based on chitosan and gelatin which showed homogeneous morphology (mean size of 1.7 ± 0.5 µm), a protective effect of the drug, and better antifungal effect against Candida culture than miconazole nitrate and the other assayed systems. Taking into account these results, this approach should be seriously considered for further evaluation of its safety and in vivo efficacy to be considered as an alternative therapeutic system for the treatment of oral candidiasis.

Effect of drug incorporation technique and polymer combination on the performance of biopolymeric antifungal buccal films.

Numerous films with a dissolved or dispersed active principle within a polymeric matrix have been described in literature. However, the incorporation of solid crystals into the films may influence several relevant properties. Additionally, it has been reported that different polymeric matrices lead to films presenting a different performance. The aim of this work was to evaluate the effect of the combination of chitosan with carrageenan (κ-, λ-, and ι-) as matrices, and of the miconazole nitrate incorporation method, on the films behavior. Mechanical properties, drug release and antifungal activity were evaluated. The state of the drug in the films was analyzed by different techniques. Films showed a homogeneous surface and a thermal protective effect on the drug. The combination of chitosan and λ-carrageenan leads to films with the highest values of tensile and mucoadhesive strength. Films with solubilized drug displayed slightly higher elongation at break, tensile and mucoadhesive strength and faster drug release than those with suspended miconazole nitrate. However, no differences were found regarding the antifungal activity of the different formulations including time-to-kill curves.

Development and Evaluation of Buccal Films Based on Chitosan for the Potential Treatment of Oral Candidiasis.

In this work, chitosan films were prepared by a casting/solvent evaporation methodology using pectin or hydroxypropylmethyl cellulose to form polymeric matrices. Miconazole nitrate, as a model drug, was loaded into such formulations. These polymeric films were characterized in terms of mechanical properties, adhesiveness, and swelling as well as drug release. Besides, the morphology of raw materials and films was investigated by scanning electron microscopy; interactions between polymers were analyzed by infrared spectroscopy and drug crystallinity studied by differential scanning calorimetry and X-ray diffraction. In addition, antifungal activity against cultures of the five most important fungal opportunistic pathogens belonging to Candida genus was investigated. Chitosan:hydroxypropylmethyl cellulose films were found to be the most appropriate formulations in terms of folding endurance, mechanical properties, and adhesiveness. Also, an improvement in the dissolution rate of miconazole nitrate from the films up to 90% compared to the non-loaded drug was observed. The in vitro antifungal activity showed a significant activity of the model drug when it is loaded into chitosan films. These findings suggest that chitosan-based films are a promising approach to deliver miconazole nitrate for the treatment of candidiasis.

Efeito da incorporação de agentes antifúngicos na resistência à tração e porosidade de materiais resilientes temporários para base de próteses / Effect of incorporation of antifungal agents on the ultimate tensile strength and porosity of temporary soft denture liners

Este estudo investigou a resistência à tração (ou limite de resistência à tração- LRT) e a porosidade de reembasadores resilientes temporários modificados por concentrações inibitórias mínimas (CIMs) de agentes antifúngicos para o biofilme Candida albicans (SC5314). Para os testes de LRT, corpos de prova em forma de halteres (n=7) com uma área transversal de 33 mm x 6 mm x 3 mm foram produzidos para os materiais resilientes (Trusoft e Softone) sem (controle) ou com incorporação de cinco fármacos em suas CIMs: nistatina- 0,032 g; diacetato de clorexidina- 0,064; cetoconazol- 0,128 g; miconazol- 0,256 g; itraconazol-0,256 g (grama de fármaco por grama de pó de material resiliente). Após a plastificação, as amostras foram imersas em água destilada a 37°C durante 24 h, 7 e 14 dias e, então, testadas em tensão em uma máquina universal de ensaios (EMIC DL-500 MF) a 40 mm/min. A porosidade foi mensurada por absorção de água, com base na exclusão do efeito plastificante. Inicialmente, determinou-se por isotermas de sorção, que a solução de armazenagem adequada para os corpos de prova (65 mm x 10 mm x 3,3 mm) de ambos os materiais foi o cloreto de cálcio anidro a 50% (S50). Assim, o fator de porosidade (FP) foi calculado para os grupos de estudo (n=10) formados por espécimes sem (controle) ou com incorporação de fármaco em suas CIMs (nistatina, clorexidina ou cetoconazol) após a armazenagem em água destilada ou S50 por 24 h, 7 e 14 dias. Os dados de resistência à tração (MPa) e percentagem de alongamento (%) foram submetidos à ANOVA de 3 fatores seguida pelo teste de Tukey (=0,05). Os dados de porosidade foram analisados estatisticamente por ANOVA de medidas repetidas para 4 fatores e teste de Tukey (=0,05). Ao final de 14 dias, a resistência à tração para ambos os materiais foi significativamente menor nos grupos modificados pelo miconazol e itraconazol em relação aos outros grupos (P<0,0001), que não mostraram diferenças significativas entre si (P>0,05). Após 7 e 14 dias em água, o miconazol e itraconazol adicionados a ambos os materiais resultaram em percentagens significativamente menores de alongamento em comparação com os outros fármacos e ao controle (P<0,0001), que foram semelhantes entre si (P>0,05). O cetoconazol não resultou em alterações significativas no FP para ambos os materiais resilientes em água ao longo de 14 dias (P>0,05). Em comparação aos controles, houve aumento dos FPs do Softone e Trusoft aos 14 dias de imersão em água somente após a adição de nistatina e clorexidina e de clorexidina, respectivamente (P<0,05). Ambos os materiais não apresentaram alterações significativas no FP em até 14 dias de imersão na S50, em comparação aos controles (P>0,05). Em todas as condições experimentais, os FPs do Softone e Trusoft foram significativamente menores quando imersos em S50 em comparação com a água destilada (P<0,05). Concluiu-se que a adição de nistatina, clorexidina e cetoconazol nas CIMs para o biofilme de C. albicans não resultou em efeitos deletérios na resistência à tração e na percentagem de alongamento dos materiais resilientes temporários para base de prótese até o período de 14 dias. A adição de antifúngicos nas CIMs não resultou em efeitos adversos à porosidade de ambos os materiais resilientes temporários em diferentes períodos de imersão em água, com exceção da clorexidina e nistatina no Softone e clorexidina no Trusoft aos 14 dias. Não foram observados efeitos deletérios para a porosidade de ambos os materiais resilientes modificados com as CIMs dos fármacos durante os 14 dias de imersão na S50.(AU)

This study investigated the tensile strength (ultimate tensile strength- UTS) and porosity of temporary soft denture liners modified by minimum inhibitory concentrations (MICs) of antifungal agents for Candida albicans biofilm (SC5314). For UTS tests, dumbbell-shaped specimens (n=7) with a central cross-sectional area of 33 mm x 6 mm x 3 mm were produced by resilient materials (Trusoft and Softone) without (control) or with incorporation of five drugs at MICs: nystatin- 0.032 g; chlorhexidine diacetate-0.064 g; ketoconazole- 0.128 g; miconazole- 0.256 g; itraconazole- 0.256 g (each per gram of soft liner powder). After plasticization, specimens were immersed in distilled water at 37°C for 24 h, 7 and 14 days, and then tested in tension in a universal testing machine (EMIC DL-500 MF) at 40 mm/min. The porosity was measured by water absorption, based on exclusion of the plasticizer effect. Initially, it was determined by sorption isotherms that the adequate storage solution for specimens (65 mm x 10 mm x 3.3 mm) of both materials was 50% anhydrous calcium chloride (S50). Then, the porosity factor (PF) was calculated for the study groups (n=10) formed by specimens without (control) or with drug incorporation at MICs (nystatin, chlorhexidine or ketoconazole) after storage in distilled water or S50 for 24 h, 7 and 14 days. Data of tensile strength (MPa) and elongation percentage (%) were submitted to 3-way ANOVA followed by Tukey's test (=0.05). Data of porosity were statistically analyzed by 4-way repeated measures ANOVA and Tukeys test (=0.05). At the end of 14 days, the tensile strength for both materials was significantly lower in the groups modified by miconazole and itraconazole compared to the other groups (P<0.0001), which showed no significant difference between them (P>0.05). After 7 and 14 days in water, miconazole and itraconazole added into both materials result in significant lower elongation percentages compared to the other drugs and control (P<.0001), which were similar to each other (P>0.05). Ketoconazole resulted in no significant changes in PF for both liners in water over 14 days (P>0.05). Compared to the controls, Softone and Trusoft PFs were increased at 14-day water immersion only after addition of nystatin and chlorhexidine, and chlorhexidine, respectively (P<0.05). Both materials showed no significant changes in PF in up to 14 days of S50 immersion, compared to the controls (P>0.05). In all experimental conditions, Softone and Trusoft PFs were significantly lower when immersed in S50 compared to distilled water (P<0.05). It was concluded that the addition of the nystatin, chlorhexidine and ketoconazole at MICs for C. albicans biofilm resulted in no harmful effects on the ultimate tensile strength and elongation percentage of the temporary soft denture liners up to 14-day period. The addition of antifungals at MICs resulted in no detrimental effects for the porosity of both temporary soft liners in different periods of water immersion, except for chlorhexidine and nystatin in Softone and chlorhexidine in Trusoft at 14 days. No deleterious effect was observed for the porosity of both soft liners modified by the drugs at MICs over 14 days of S50 immersion.(AU)

A facile synthesis of novel miconazole analogues and the evaluation of their antifungal activity.

Four novel miconazole analogues (8-11) were synthetized and evaluated for activity against four filamentous fungi (Mucor hiemalis, Aspergillus fumigatus, Trichosporon cutaneum, and Rhizopus oryzae) and eight species of Candida as yeast specimens. Compounds 9 and 10 showed very good activity when evaluated in yeast (MIC 0.112 and 0.163 µg/mL) compared to the reference compound, itraconazole (MIC 0.067 µg/mL). The best antifungal activity in filamentous strains was shown by compound 9. Hence compounds 9 and 10 represent new leads for further pharmacomodulation in this series.

Molecularly imprinted solid phase extraction of fluconazole from pharmaceutical formulations.

This work encompasses a direct and coherent strategy to synthesise a molecularly imprinted polymer (MIP) capable of extracting fluconazole from its sample. The MIP was successfully prepared from methacrylic acid (functional monomer), ethyleneglycoldimethacrylate (crosslinker) and acetonitrile (porogenic solvent) in the presence of fluconazole as the template molecule through a non-covalent approach. The non-imprinted polymer (NIP) was prepared following the same synthetic scheme, but in the absence of the template. The data obtained from scanning electronic microscopy, infrared spectroscopy, thermogravimetric and nitrogen Brunauer-Emmett-Teller plot helped to elucidate the structural as well as the morphological characteristics of the MIP and NIP. The application of MIP as a sorbent was demonstrated by packing it in solid phase extraction cartridges to extract fluconazole from commercial capsule samples through an offline analytical procedure. The quantification of fluconazole was accomplished through UPLC-MS, which resulted in LOD≤1.63×10(-10) mM. Furthermore, a high percentage recovery of 91±10% (n=9) was obtained. The ability of the MIP for selective recognition of fluconazole was evaluated by comparison with the structural analogues, miconazole, tioconazole and secnidazole, resulting in percentage recoveries of 51, 35 and 32%, respectively.

Effect of the addition of antimicrobial agents on Shore A hardness and roughness of soft lining materials.

PURPOSE: While the incorporation of antimicrobial agents into soft denture liners has been suggested as a reliable alternative treatment for denture stomatitis, it may affect the liner's properties. The effect of addition of antimicrobial agents for the treatment of denture stomatitis on the surface roughness and Shore A hardness of soft lining materials was evaluated. MATERIALS AND METHODS: The test groups comprised specimens (36 × 7 × 6 mm(3) ) of soft materials (Softone and Trusoft) without (control) or with incorporation of drugs (nystatin, miconazole, ketoconazole, chlorhexidine diacetate, and itraconazole). Hardness (Shore A) and roughness (Ra) were evaluated after immersion of specimens (n = 10) in distilled water at 37°C for 24 hours, 7 and 14 days. Data were analyzed by 3-way ANOVA/Tukey's test (α = 0.05). RESULTS: After 14 days, an increase (p < 0.05) was observed in the hardness of soft materials with time for the modified specimens, except for itraconazole. Addition of drugs increased the Softone roughness only for the addition of miconazole and chlorhexidine (p < 0.05), and did not increase the roughness of Trusoft with time. Only chlorhexidine and itraconazole altered the roughness compared to the control for each material (p < 0.05). CONCLUSIONS: The smallest changes of hardness and roughness with time in the modified groups compared to controls were observed for itraconazole groups for both materials.

Evaluación de métodos cromatográficos para la estabilidad química del nitrato de miconazol en una nueva crema / Assessment of chromatographic methods for the chemical stability of a new miconazol nitrate cream

Objetivo: evaluar los métodos cromatográficos para la estabilidad química del nitrato de miconazol en una nueva crema al 2 por ciento. Métodos: en primer lugar se aplicaron diferentes condiciones degradativas al nitrato de miconazol materia prima a fin de obtener los posibles productos de degradación del fármaco y evaluarlos por un método diseñado por cromatografía en capa delgada, el cual se validó para identificar productos de degradación en la crema. Se evaluó el desempeño del método oficial informado en la Farmacopea Británica 2010 por cromatografía líquida de alta resolución para la valoración del nitrato de miconazol en la crema, analizando su selectividad frente a los posibles productos de degradación. Ambos métodos cromatográficos fueron aplicados al análisis de muestras de crema procedentes de los tres lotes pilotos sometidos a estrés térmico durante 30 días. Resultados: ambos métodos mostraron elevada selectividad frente a los excipientes y los productos de degradación del fármaco. Se obtuvo degradación del nitrato de miconazol frente a hidrólisis ácida, termólisis y fotólisis y el límite de detección fue de 1 µg para cromatografía en capa delgada. No se mostró degradación del analito según los resultados cualitativos y cuantitativos en ninguno de los tres lotes analizados. Conclusiones: los métodos utilizados son válidos para el objetivo con el cual se proponen, por lo que pueden emplearse en el estudio de estabilidad química de las cremas de nitrato de miconazol al 2 por ciento(AU)

Objective: to assess the chromatographic methods for the chemical stability of a new 2 percent miconazol nitrate cream. Methods: various degradation conditions were firstly used in the raw material miconazole nitrate in order to obtain the possible degradation products of this drug and to evaluate them by thin layer chromatography-based method, which was validated to identify the degradation products in the new cream. The performance of the official method based on high resolution liquid chromatography and reported in British Pharmacopeia 2010 was evaluated, and its selectivity against the possible degradation products were also analyzed. Both chromatographic methods were applied to the analysis of cream samples from the three pilot batches under heat stress for 30 days. Results: the two methods showed high selectivity against excipients and degradation products of the drug. Miconazol nitrate was degraded against acid hydrolysis, thermolysis and photolysis, being the detection limit of 1 µg for the thin layer chromatography. No degradation of the analyte was observed in any of the three analyzed batches according to the qualitative and quantitative results. Conclusions: these methods are valid for the submitted objective, so they may be used in the chemical stability study of 2 percent miconazol nitrate creams(AU)

Evaluación de métodos cromatográficos para la estabilidad química del nitrato de miconazol en una nueva crema / Assessment of chromatographic methods for the chemical stability of a new miconazol nitrate cream

Objetivo: evaluar los métodos cromatográficos para la estabilidad química del nitrato de miconazol en una nueva crema al 2 por ciento. Métodos: en primer lugar se aplicaron diferentes condiciones degradativas al nitrato de miconazol materia prima a fin de obtener los posibles productos de degradación del fármaco y evaluarlos por un método diseñado por cromatografía en capa delgada, el cual se validó para identificar productos de degradación en la crema. Se evaluó el desempeño del método oficial informado en la Farmacopea Británica 2010 por cromatografía líquida de alta resolución para la valoración del nitrato de miconazol en la crema, analizando su selectividad frente a los posibles productos de degradación. Ambos métodos cromatográficos fueron aplicados al análisis de muestras de crema procedentes de los tres lotes pilotos sometidos a estrés térmico durante 30 días. Resultados: ambos métodos mostraron elevada selectividad frente a los excipientes y los productos de degradación del fármaco. Se obtuvo degradación del nitrato de miconazol frente a hidrólisis ácida, termólisis y fotólisis y el límite de detección fue de 1 µg para cromatografía en capa delgada. No se mostró degradación del analito según los resultados cualitativos y cuantitativos en ninguno de los tres lotes analizados. Conclusiones: los métodos utilizados son válidos para el objetivo con el cual se proponen, por lo que pueden emplearse en el estudio de estabilidad química de las cremas de nitrato de miconazol al 2 por ciento

Objective: to assess the chromatographic methods for the chemical stability of a new 2 percent miconazol nitrate cream. Methods: various degradation conditions were firstly used in the raw material miconazole nitrate in order to obtain the possible degradation products of this drug and to evaluate them by thin layer chromatography-based method, which was validated to identify the degradation products in the new cream. The performance of the official method based on high resolution liquid chromatography and reported in British Pharmacopeia 2010 was evaluated, and its selectivity against the possible degradation products were also analyzed. Both chromatographic methods were applied to the analysis of cream samples from the three pilot batches under heat stress for 30 days. Results: the two methods showed high selectivity against excipients and degradation products of the drug. Miconazol nitrate was degraded against acid hydrolysis, thermolysis and photolysis, being the detection limit of 1 µg for the thin layer chromatography. No degradation of the analyte was observed in any of the three analyzed batches according to the qualitative and quantitative results. Conclusions: these methods are valid for the submitted objective, so they may be used in the chemical stability study of 2 percent miconazol nitrate creams

Peel bond strength of resilient liner modified by the addition of antimicrobial agents to denture base acrylic resin

In order to prolong the clinical longevity of resilient denture relining materials and reduce plaque accumulation, incorporation of antimicrobial agents into these materials has been proposed. However, this addition may affect their properties. OBJECTIVE: This study evaluated the effect of the addition of antimicrobial agents into one soft liner (Soft Confort, Dencril) on its peel bond strength to one denture base (QC 20, Dentsply). MATERIAL AND METHODS: Acrylic specimens (n=9) were made (75x10x3 mm) and stored in distilled water at 37ºC for 48 h. The drug powder concentrations (nystatin 500,000U - G2; nystatin 1,000,000U - G3; miconazole 125 mg - G4; miconazole 250 mg - G5; ketoconazole 100 mg - G6; ketoconazole 200 mg - G7; chlorhexidine diacetate 5% - G8; and 10% chlorhexidine diacetate - G9) were blended with the soft liner powder before the addition of the soft liner liquid. A group (G1) without any drug incorporation was used as control. Specimens (n=9) (75x10x6 mm) were plasticized according to the manufacturers' instructions and stored in distilled water at 37ºC for 24 h. Relined specimens were then submitted to a 180-degree peel test at a crosshead speed of 10 mm/min. Data (MPa) were analyzed by analysis of variance (α=0.05) and the failure modes were visually classified. RESULTS: No significant difference was found among experimental groups (p=0.148). Cohesive failure located within the resilient material was predominantly observed in all tested groups. CONCLUSIONS: Peel bond strength between the denture base and the modified soft liner was not affected by the addition of antimicrobial agents.

Preparation and characterization of biomimetic nanoparticles for drug delivery.

Biomimetic nanoparticles are hybrid nanostructures in which the uppermost layer is similar to a cell membrane. This report provides instructions for the preparation and physical characterization of three different types of biomimetic nanoparticles: (1) polystyrene sulfate nanoparticles covered with one cationic dioctadecyldimethylammonium bilayer; (2) silica nanoparticles covered with one neutral phosphatidylcholine bilayer; (3) miconazole particles covered with one anionic dihexadecylphosphate (DHP) bilayer. These examples provide the basis for the preparation and characterization of novel nanoparticles from hydrophobic or hydrophilic and organic or inorganic nanoparticle cores covered with functional outer layers. The major concepts and technical details for obtaining the optimal lipid coverage of supporting cores and for nanoparticle characterization are discussed.

Peel bond strength of resilient liner modified by the addition of antimicrobial agents to denture base acrylic resin.

UNLABELLED: In order to prolong the clinical longevity of resilient denture relining materials and reduce plaque accumulation, incorporation of antimicrobial agents into these materials has been proposed. However, this addition may affect their properties. OBJECTIVE: This study evaluated the effect of the addition of antimicrobial agents into one soft liner (Soft Confort, Dencril) on its peel bond strength to one denture base (QC 20, Dentsply). MATERIAL AND METHODS: Acrylic specimens (n=9) were made (75x10x3 mm) and stored in distilled water at 37 ºC for 48 h. The drug powder concentrations (nystatin 500,000 U--G2; nystatin 1,000,000 U--G3; miconazole 125 mg--G4; miconazole 250 mg--G5; ketoconazole 100 mg - G6; ketoconazole 200 mg--G7; chlorhexidine diacetate 5%--G8; and 10% chlorhexidine diacetate--G9) were blended with the soft liner powder before the addition of the soft liner liquid. A group (G1) without any drug incorporation was used as control. Specimens (n=9) (75x10x6 mm) were plasticized according to the manufacturers' instructions and stored in distilled water at 37 ºC for 24 h. Relined specimens were then submitted to a 180-degree peel test at a crosshead speed of 10 mm/min. Data (MPa) were analyzed by analysis of variance (α=0.05) and the failure modes were visually classified. RESULTS: No significant difference was found among experimental groups (p=0.148). Cohesive failure located within the resilient material was predominantly observed in all tested groups. CONCLUSIONS: Peel bond strength between the denture base and the modified soft liner was not affected by the addition of antimicrobial agents.

Ketoconazole and miconazole alter potassium homeostasis in Saccharomyces cerevisiae.

The effects of ketoconazole and miconazole uptake on K(+) transport and the internal pH of Saccharomyces cerevisiae were studied. The uptake of both drugs was very fast, linear with concentration and not dependent on glucose, indicating entrance by diffusion and concentrating inside. Low (5.0µM) to intermediate concentrations (40µM) of both drugs produced a glucose-dependent K(+) efflux; higher ones also produced a small influx of protons, probably through a K(+)/H(+) exchanger, resulting in a decrease of the internal pH of the cells and the efflux of material absorbing at 260nm and phosphate. The cell membrane was not permeabilized. The K(+) efflux with miconazole was dependent directly on the medium pH. This efflux results in an increased membrane potential, responsible for an increased Ca(2+) uptake and other effects. These effects were not observed with two triazolic antifungals. A decrease of the Zeta (ζ) potential was observed at low concentrations of miconazole. Although the main effect of these antifungals is the inhibition of ergosterol synthesis, K(+) efflux is an important additional effect to be considered in their therapeutic use. Under certain conditions, the use of single mutants of several transporters involved in the movements of K(+) allowed to identify the participation of several antiporters in the efflux of the cation.

Superficial distribution and identification of antifungal/antimicrobial agents on a modified tissue conditioner by SEM-EDS microanalysis: a preliminary study.

PURPOSE: This study evaluated the incorporation pattern of antifungal/antimicrobial agents added to a tissue conditioner by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) analysis. MATERIALS AND METHODS: The nystatin dosages incorporated into the tissue conditioner (Softone, Bosworth Co., Skokie, IL) powder were 500,000 U (G1) and 1,000,000 U (G2). The addition of miconazole was at 125 mg (G3) and 250 mg (G4), and ketoconazole was at 100 mg (G5) and 200 mg (G6). Chlorhexidine diacetate was blended at levels of 5% (G7) and 10% (G8) w/w of the total amount (6.35 g) of the tissue conditioner. The drug powder concentrations were blended with the tissue conditioner powder at different concentrations before the addition of the tissue conditioner liquid (5 mL) to the mixture. One group (G0) without any drug incorporation was used as control. Specimens (n = 5) (36 x 7 x 6 mm(3)) were plasticized at room temperature for 10 minutes and carbon sputter coated. All specimens were submitted to SEM-EDS analysis. RESULTS: Nystatin and miconazole specimens exhibited particles with irregular shapes and sizes uniformly distributed. Ketoconazole specimens showed small spherical particles with a slight distribution throughout the matrix. Chlorhexidine specimens exhibited irregular particles up to approximately 50 mum in size randomly dispersed within the matrix. CONCLUSIONS: Within the limitations of this in vitro study, the modified tissue conditioner showed differences in the particle distribution and size of the antifungal/antimicrobial agent added to the plasticized matrix. Further studies would discriminate the most important particle features that may influence the drug leaching from the plasticized matrix.

Lipid-covered drug particles: combined action of dioctadecyldimethylammonium bromide and amphotericin B or miconazole.

OBJECTIVES: Coverage of antifungal drug particles (miconazole and amphotericin B) with cationic lipid and evaluation of a synergistic action between lipid and drug. METHODS: Miconazole and amphotericin B were mixed with cationic bilayer fragments (BF) of dioctadecyldimethylammonium bromide (DODAB) at extreme drug to lipid molar proportions (P). Light scattering for particle sizing and zeta-potential analysis evaluated effects of cationic lipid on drug particle size and charge. Colony counts evaluated viability of Candida spp. and Cryptococcus neoformans over a range of P. RESULTS: BF loading capacity for monomeric amphotericin B is 0.1 mM amphotericin B at 2 mM DODAB (P = 1:20). Above this low P, amphotericin B aggregates in the dispersion. At high P, addition of chaotropic K2HPO4 (0.2-2 mM) converts miconazole or amphotericin B aggregates into negatively charged particles with affinity for cationic lipid, which then surrounds each drug particle with a cationic layer. The combined in vitro action of lipid-covered drug particles against Candida and C. neoformans depends on P and interaction time. DODAB by itself kills C. neoformans and Candida at 2 and 2 to > 250 mg/L minimal fungicidal concentration (MFC). In combination, over the first hour, fungicidal activity is due to DODAB with lipid capsules retarding drug action. At 48 h interaction time and 10(4) cfu/mL, MFC (mg/L) against Candida albicans is reduced from 4 to 1 amphotericin B (at 2 DODAB), and from 8 to 1 miconazole (at 1 DODAB). CONCLUSIONS: DODAB may be a suitable candidate for use in combination with miconazole for antifungal therapy.

Assembly of a model hydrophobic drug into cationic bilayer fragments.

Our previous work has shown that dioctadecyldimethylammonium bromide (DODAB) bilayer fragments (BF) presented antimicrobial activity, solubilized fungicides, e.g., amphotericin B and miconazole (MCZ), stabilized hydrophobic drug particles and were effective in vivo. Here, the interaction between MCZ and DODAB BF is evaluated from determination of BF loading capacity and effects of drug-to-lipid molar proportion (MP) on particle size, zeta potential and gel-to-liquid-crystalline phase transition T(m). DODAB BF solubilized MCZ over a range of MP. BF loading capacity was 0.5 mM MCZ at 5 mM DODAB. Above this limit, the drug aggregated in the dispersion. At pH 6.3, BF zeta potentials decreased with MP, suggesting insertion of deprotonated drug into the bilayer. MCZ optical spectra in BF were similar to those in best organic solvent, confirming drug solubilization. At MP 1:10, BF T(m) remained unchanged, suggesting drug capture at BF hydrophobic edges. At MP 1:10, T(m) decreased, showing MCZ insertion into DODAB bilayer. However, drug was expelled from the bilayer core upon lowering temperature. Minimal fungicidal concentrations against C. albicans were synergically reduced by 10 times for drug/BF.

Voltammetric characteristics of miconazole and its cathodic stripping voltammetric determination.

Miconazole is reduced at mercury electrode above pH 6 involving organometallic compound formation, responsible for an anomalous polarographic behavior. The electrodic process presents a large contribution of the adsorption effects. The drug can be determined by cathodic stripping voltammetry from 8.0 x 10(-8) to 1, 5 x 10(-6) molL-1 in Britton-Robinson buffer pH 8.0, when pre-accumulated for 30s at an accumulation potential of 0V. A relative standard deviation of 3.8% was obtained for ten measurements of 1.0 x 10(-7) molL-1 miconazole in B-R buffer pH 8.0 and a limit detection of 1, 7 x 10(-8) molL-1 was determined using 60s of deposition time and scan rate of 100 mVs-1. The proposed method is simple, precise and it was applied successfully for the determination of the miconazole in pure form and in commercial formulations, showing mean recoveries of 99.7-98.4%.