Interactions of "de novo" designed peptides with bacterial membranes: Implications in the antimicrobial activity.

Antimicrobial peptides are small molecules that display antimicrobial activity against a wide range of pathogens. In a previous work, by using model membranes we studied P6, a peptide that shows no antimicrobial activity, and P6.2, which exhibits antibacterial activity. In the present work we aimed to unravel the mode of action of these peptides by studying their interaction in vivo with Escherichia coli and Staphylococcus aureus. In this sense, to study the interactions with bacterial cells and their effect on the bacterial surface, zeta potential, spectroscopic, and microscopic methodologies were applied. P6.2 exhibits a higher affinity toward both bacterial envelopes. The ability of both peptides to disrupt afterwards the bacterial membrane was also studied. Both peptides were able to induce bacterial membrane damage, but higher concentrations of P6 were needed to obtain results comparable to those obtained for P6.2. Additionally, P6.2 exhibited faster damage kinetics. Altogether, these data allow postulating, in a physiologic model, that the lower affinity of P6 for bacterial envelope results in a minor final concentration of the peptide in the bacterial membrane unable to trigger the antimicrobial activity. Finally, the fact that the active P6.2 has the same MIC value for the Gram-positive and Gram-negative bacteria tested, but not the same profile in the permeabilization assays, reinforces the question of whether cell wall components act as electrostatic barriers preventing or minimizing membrane-active AMPs lethal action at the membrane level.

Hybrid Ofloxacin/eugenol co-loaded solid lipid nanoparticles with enhanced and targetable antimicrobial properties.

In the global context of an imminent emergence of multidrug-resistant microorganisms, the present work combined the use of nanotechnology and the therapeutic benefits of natural compounds as a strategy to potentiate antimicrobial action of the wide-spectrum antibiotic Ofloxacin (Ofx). Hybrid solid lipid nanoparticles (SLN) were synthesized by incorporation of chitosan (Chi, a cationic biopolymer with antimicrobial activity) and eugenol (Eu, a phenolic compound that interferes with bacterial quorum sensing) into a lipid matrix by hot homogenization/ultrasonication method. The developed SLN/Chi/Eu sustainably released the encapsulated Ofx for 24 h. Characterization by DLS, TEM, DSC, TGA and XRD revealed the presence of positively charged spherical nanoparticles with diameters around 300 nm and Ofx entrapped in amorphous state. The SLN exhibited an enhanced bactericidal activity against Pseudomonas aeruginosa and Staphylococcus aureus. The minimum inhibitory concentration (MIC) for free and nanoencapsulated Ofx formulations was below 1.0 µg/ml. The MIC values decreased by 6.1- to 16.1-fold when Ofx was encapsulated in SLN/Chi/Eu. Fluorescent-labeled nanoparticles had the ability to interact with the bacterial cell membrane. Selective toxicity of SLN/Chi/Eu-Ofx was tested in the range of 0.3-30.0 µg/ml and showed no toxicity up to 3.0 µg/ml Ofx in human cell models (A549 and Wi-38) at 24 h and 48 h exposure. It was proved that the administration of hybrid SLN to mice by dry powder inhalation reached therapeutic Ofx levels in lungs.

Plano de ação nacional de prevenção e controle da resistência aos antimicrobianos no âmbito da saúde única: 2018-2022 / National Action Plan for the Prevention and Control of Antimicrobial Resistance in the One Health Framework: 2018-2022

No presente documento, é apresentado o Plano Estratégico do PAN-BR (formato executivo), que contém 14 Objetivos Principais, 33 Intervenções Estratégicas e 75 Atividades, alinhados aos 5 Objetivos Estratégicos do Plano de Ação Global.

Antimicrobial and antibiofilm activities of phenolic compounds extracted from Populus nigra and Populus alba buds (Algeria)

The interest of this work is the discovery of new antimicrobial agents of plant origin to inhibit the formation of microbial biofilms. The present research was conducted to identify and quantify the phenolic compounds extracted from Populus nigra and Populus alba buds harvested in the area of Tizi-Ouzou (Algeria), and to evaluate their antimicrobial and antibiofilm activity. High performance liquid chromatography (HPLC) was performed to identify the phenolic compounds in the ethyl acetate fraction of P. nigra and the methanolic extracts of P. nigra and P. alba. The antimicrobial activity of the crude extracts and the fractions of these two species was tested against 11 microorganisms, using the disk diffusion method, while the antibiofilm effect of certain extracts was carried out in a 96-well microplate and on a biomaterial (catheter). HPLC analysis revealed the presence of 10 bioactive compounds. The main phenolic compounds identified in the three extracts were p-coumaric acid, ellagic acid, and Kaempferol. This study was able to demonstrate that the extracts of P. nigra and P. alba buds have interesting antimicrobial properties, with diameters ranging from 6.6 to 21.3 mm. In addition, extracts of P. nigra exhibited antibiofilm effects greater than 70%. Our results provide evidence for the antimicrobial and antibiofilm potential of bud extracts from both poplar species. Thus, these results will pave the way for further research on these two plants.

Electrochemical remediation of amoxicillin: detoxification and reduction of antimicrobial activity.

Amoxicillin (AMX) is one of the most commonly prescribed antibiotics around the world to treat and prevent several diseases in both human and veterinary medicine. Incomplete removal of AMX during wastewater treatment contributes to its presence in water bodies and drinking water. AMX is an emerging contaminant since its impact on the environment and human health remains uncertain. This contribution was aimed to evaluate the electrochemical oxidation (EO) of AMX using different anodes in tap water, NaCl or Na2SO4 solutions and to evaluate the potential toxicity of remaining AMX and its by-products on zebrafish early-life stages. Chemical intermediates generated after EO were determined by mass spectrometry and their resulting antimicrobial activity was evaluated. AMX did not induce significant mortality in zebrafish during extended exposure but affected zebrafish development (increased body length) from 6.25 mg/L to 25 mg/L and inhibited enzymatic biomarkers. Carbon modified with titanium oxide (TiO2@C) anode achieved complete AMX removal in just a few minutes and efficiency of the supported electrolytes occurred in the following order: 0.1 M NaCl > 0.1 M Na2SO4 > 0.01 M NaCl > tap water. The order of potential toxicity to zebrafish early life-stages related to lethal and sublethal effects was as follows: 0.1 M Na2SO4 > 0.1 M NaCl >0.01 M NaCl = tap water. Additionally, the EO of AMX using TiO2@C electrode with 0.01 M NaCl was able to inhibit the antimicrobial activity of AMX, reducing the possibility of developing bacterial resistance.

Influence of chemical and physical conditions in selection of Gluconacetobacter hansenii ATCC 23769 strains with high capacity to produce bacterial cellulose for application as sustained antimicrobial drug-release supports.

AIMS: Obtain varieties of Gluconacetobacter hansenii from original strain ATCC 23729 with greater efficiency to produce bacterial cellulose (BC) membrane with better dry mass yield for application as support of sustained antimicrobials' drug release. METHODS AND RESULTS: Application of different chemical and physical conditions (pH, temperature and UV light exposure) to obtain different G. hansenii varieties with high capacity to produce BC membranes. Characterization of the G. hansenii variants was performed by scanning electron microscopy (SEM) and optical microscopy of the colony-forming units. BC membrane produced was characterized by SEM, infrared spectroscopy and X-ray diffraction. The BC produced by variants isolated after incubation at 35°C showed elevated dry mass yield and high capacity of retention and sustained release of ceftriaxone antibiotic with the produced BC by original G. hansenii ATCC 23769 strain subjected to incubation at 28°C and with commercial BC. CONCLUSION: The application of different chemical and physical conditions constitutes an important method to obtain varieties of micro-organisms with dissimilar metabolism advantageous in relation to the original strain in the BC production. SIGNIFICANCE AND IMPACT OF THE STUDY: These results demonstrate the importance of in vivo studies for the application, in medicine, of BC membranes as support for antimicrobial-sustained release for the skin wound treatment.

Racionalização de antimicrobianos em ambiente hospitalar / Antimicrobial stewardship program in hospitals

Foi feita uma revisão sobre o uso racional de antimicrobianos em ambiente hospitalar, pois este é um dos principais desafios encontrados na terapia de infecções em ambiente hospitalar. Foram abordados os principais fatores que nos levam ao atual panorama global em relação à resistência antimicrobiana, bem como as principais estratégias para o uso racional dos antimicrobianos, de modo a garantir melhor terapêutica e menor incidência de resistência aos antimicrobianos. A racionalização de antimicrobianos é um componente-chave de uma abordagem multifacetada para a prevenção de resistência antimicrobiana. A boa gestão de antimicrobianos envolve a seleção do medicamento apropriado, otimizando sempre a dose e a duração do tratamento, utilizando bem os parâmetros de farmacodinâmica e farmacocinética, minimizando a toxicidade e as condições para a seleção de cepas bacterianas resistentes e garantindo, assim, sucesso terapêutico. Com o uso racional de antimicrobianos, podemos obter um melhor desempenho no tratamento de doenças infecciosas. Nesta revisão foi demonstrada a existência de várias estratégias de racionalização de antimicrobianos. Portanto, cabe a cada instituição estudar e analisar quais métodos devem ser implantados. Também é de fundamental importância que o prescritor analise as opções terapêuticas disponíveis e busque a individualização do tratamento, sempre visando à otimização terapêutica.(AU)

A review on antimicrobial stewardship was performed, because this is one of the leading challenges found in infectious diseases therapy in hospital settings. The major factors leading to the current global picture regarding antimicrobial resistance, and the main strategies for antimicrobial stewardship, to ensure the best treatment and lower incidence of antimicrobial resistance were discussed. Antimicrobial stewardship is a multifaceted approach considered a key component in the prevention of antimicrobial resistance. The best antimicrobial stewardship program involves selecting the appropriate medication, always optimizing its dose and duration of treatment using pharmacodynamics and pharmacokinetics parameters, minimizing toxicity and the conditions for selecting resistant bacterial strains, and ensuring treatment success. The rational use of antimicrobials can lead to more success in the treatment of infectious diseases. This review shows several strategies for antimicrobial stewardship. Therefore, it is up to each institution to study and analyze which method should be implemented. It is also crucial that the prescriber reviews the therapeutic options available to seek individualization of treatment, always aiming at therapy optimization.(AU)

The use of antimicrobials in septic patients with acute kidney injury.

Sepsis is the most common cause of death in critically ill patients and it may be associated with multiorgan failure, including acute kidney injury (AKI). This situation can require acute renal support and increase mortality. Therefore, it is essential to administrate antimicrobials in dosis to achieve adequate serum levels, preventing overdosis and drug toxicity or underdosing and risk for resistance to antibiotics and higher mortality. To date, there aren't validated guidelines on antibiotic dosis adjustment in septic patients with AKI and the recommendations are extrapolated from studies conducted in non-critical patients with chronic kidney disease in end stage receiving chronic renal replacement therapy. This study aimed to review and discuss the complexity of that issue, considering the several factors related to the drugs removal: critically ill patient characteristics, antimicrobial properties and dialysis method.

The use of antimicrobials in septic patients with acute kidney injury / O uso de antimicrobianos em pacientes sépticos com lesão renal aguda

Abstract Sepsis is the most common cause of death in critically ill patients and it may be associated with multiorgan failure, including acute kidney injury (AKI). This situation can require acute renal support and increase mortality. Therefore, it is essential to administrate antimicrobials in dosis to achieve adequate serum levels, preventing overdosis and drug toxicity or underdosing and risk for resistance to antibiotics and higher mortality. To date, there aren't validated guidelines on antibiotic dosis adjustment in septic patients with AKI and the recommendations are extrapolated from studies conducted in non-critical patients with chronic kidney disease in end stage receiving chronic renal replacement therapy. This study aimed to review and discuss the complexity of that issue, considering the several factors related to the drugs removal: critically ill patient characteristics, antimicrobial properties and dialysis method.

Resumo A sepse é a principal causa de óbito em pacientes críticos e pode cursar com falência de vários órgãos, entre eles os rins, requerendo, com frequência, suporte renal agudo e elevando a mortalidade. Assim, torna-se imprescindível a administração de antimicrobianos em dose que garanta nível sérico adequado para evitar superdosagem e toxicidade medicamentosa ou ainda subdosagem e risco de resistência microbiana, ambas as situações contribuindo para maior mortalidade. Até o momento, não há diretrizes validadas para auxiliar no ajuste de dose de antibióticos nos pacientes sépticos com lesão renal aguda em suporte renal, sendo as recomendações extrapoladas de estudos realizados em pacientes não críticos e com doença renal em estádio final recebendo terapia renal substitutiva crônica. Esse estudo teve como objetivo revisar e discutir a complexidade desse assunto, levando em consideração os vários fatores relacionados à remoção de drogas: características do paciente crítico, propriedades dos antimicrobianos e método dialítico utilizado.

Prescripción de antimicrobianos y su relación con la resistencia bacteriana en un hospital general municipal / Antimicrobians prpescription and their relationship with the bacterial resistance in a municipal general hospital

Se realizó un estudio descriptivo y transversal, de utilización de medicamentos de tipo prescripción-indicación, de los 303 adultos que recibieron tratamiento antimicrobiano, ingresados en los servicios de Cuidados Intensivos, Medicina Interna y Cirugía del Hospital General Orlando Pantoja Tamayo del municipio de Contramaestre, desde enero hasta junio de 2015, con vistas a evaluar la prescripción de estos medicamentos y su relación con la resistencia bacteriana. En la serie, de un total de 568 prescripciones evaluadas predominaron las inadecuadas (82,3 por ciento); asimismo, los antimicrobianos más prescriptos resultaron ser la cefuroxima y la ceftriaxona, que también presentaron el mayor número de cepas resistentes y el Staphylococcus aureus resultó ser el germen con mayor resistencia

A descriptive and cross-sectional study on the use of prescription-indication medications of the 303 adults that received antimicrobian treatment was carried out. They were admitted to the Intensive Care, Internal Medicine and Surgery services of Orlando Pantoja Tamayo General Hospital in Contramaestre, from January to June, 2015, aimed at evaluating the prescription of these medications and their relationship with the bacterial resistance. In the series, there was a prevalence of inadequate prescriptions (82.3 percent) from a total of 568 that were evaluated; also, the most prescribed antimicrobians were the cefuroxime and the ceftriaxone that also presented the highest number of resistant stumps and the Staphylococcus aureus was the germ with higher resistance

Purification, biochemical characterization, and antimicrobial activity of a new lipid transfer protein from Coffea canephora seeds.

Coffee, an agronomical crop of great economic importance, is also among the most commonly traded commodities in worldwide markets. Antimicrobial peptides, which play a role in plant defense, have been identified and isolated particularly from seeds. We isolated and immunolocalized Cc-LTP2, a new lipid transfer protein (LTP) from Coffea canephora seeds. We report its antimicrobial activity against various phytopathogenic fungi of economic importance, and against the bacterium Xanthomonas euvesicatoria. Peptides from C. canephora seeds were initially extracted using acid buffer and subjected to ion-exchange and reverse-phase chromatographies. A purified peptide of approximately 9 kDa, which we named Cc-LTP2, was then subjected to amino acid sequencing. The analyses showed that it was similar to LTPs isolated from various plants. The tissue and subcellular localization of C. canephora LTPs indicated that they were located in cell walls and intracellular palisade parenchyma, mainly in large vacuoles. The results of immunohistochemistry and histochemistry superposed from C. canephora seed tissues showed that LTPs and lipid bodies are present in organelles, supporting the hypothesis that LTPs from seeds are involved in lipid mobilization during germination. Cc-LTP2 did inhibit the development of the phytopathogenic fungi Colletotrichum lindemuthianum, Colletotrichum gloeosporioides, Fusarium solani, Fusarium lateritium, and Colletotrichum sp, but did inhibit X. euvesicatoria. Cc-LTP2 also increased membrane permeability and induced endogenous production of reactive oxygen species in all the fungi tested.

Uptake and biodegradation of the antimicrobial sulfadimidine by the species Tripolium pannonicum acting as biofilter and its further biodegradation by anaerobic digestion and concomitant biogas production.

This project analyses the uptake and biodegradation of the antimicrobial sulfadimidine (SDI) from the culture medium and up to the anaerobic digestion. Tripolium pannonicum was grown under hydroponic conditions with different concentrations of SDI (0, 5 and 10mg·L(-1)) and the fresh biomass, containing different amounts of SDI taken up, was used as substrate for biogas production. SDI was analyzed by liquid chromatography coupled to positive ion electrospray mass spectrometry (ESI LC-MS). Based on the findings, T. pannonicum is able to uptake SDI. The more SDI is in the culture medium, the higher the SDI content in the plant tissue. According to this study, it is possible to produce high yields of biogas using biomass of T. pannonicum containing SDI and at the same time biodegradation of SDI is carried out. The highest specific biogas yield is obtained using shoots as substrate of the plants cultivated at 5mg·L(-1) SDI.

Biopharmaceutical Characterization of Nebulized Antimicrobial Agents in Rats: 5. Oseltamivir Carboxylate.

The aim of this study was to determine the biopharmaceutical characteristics of oseltamivir carboxylate (OC) after pulmonary delivery. After OC bolus and intratracheal nebulization (NEB) in rats, blood was collected and bronchoalveolar lavages (BALs) were performed. Epithelial lining fluid (ELF) concentrations were estimated from BAL fluid. The area under the curve (AUC) ratio for ELF to plasma was 842 times higher after NEB than after intravenous (i.v.) administration, indicating that OC nebulization offers a biopharmaceutical advantage over i.v. administration.

Improving the antidepressant action and the bioavailability of sertraline by co-crystallization with coumarin 3-carboxylate. Structural determination.

To improve the antidepressant action of sertraline a new salt with coumarin-3-carboxylate anion (SerH-CCA) has been synthesized by two different methods and characterized by FTIR spectroscopy and structural determinations by X-ray diffraction methods. The new salt is stabilized by strong intermolecular H-bonds involving the protonated amine group of SerH and the deprotonated carboxylate group of CCA. These findings can be correlated with the interpretation of the infrared spectrum. The salt, sertraline (SerHCl) and the sodium salt of coumarin-3-carboxylate (NaCCA) were orally administered male Wistar rats (10 mg/kg, based on sertraline). Rats were evaluated in separate groups by means of the forced swimming (FST). SerH-CCA produced antidepressant effects in a magnitude that exceeded SerHCl individual effects. None of these treatments affected activity levels by the open field OFT tests. We have also determined that the ion pair also improve the binding to bovine serum albumin (BSA) of the drug but retain its antimicrobial activity. It is reasonable to conclude that the replacement of chloride anion by a large organic anion in sertraline strengthens the pharmacological action of the native drug, binding to BSA with higher activity and retaining the antimicrobial activity of the antidepressant compound.

Phytoconstituents from Sidastrum micranthum (A. St.-Hil.) Fryxell (Malvaceae) and antimicrobial activity of pheophytin a

abstract Sidastrum micranthum (A. St.-Hil.) Fryxell, a member of the Malvaceae family, is called malva preta in Brazil. As this species is commonly used to treat bronchitis, cough, and asthma, better knowledge of its chemical compounds is important. The phytochemical study of its hexane extract, using chromatographic techniques, led to isolation of six compounds: the triterpene isoarborinol, a mixture of sitosterol and stigmasterol, sitosterol-3-O-β-D-glucopyranoside, pheophytin a, and 132-hydroxy-(132-S)-pheophytin a. Structural identification of these compounds was carried out using spectroscopic methods such as IR and 1D and 2D NMR (HOMOCOSY, HMQC, HMBC, and NOESY). Compounds isolated from S. micranthum were screened for their in vitro antifungal and antibacterial activity against twenty fungal and bacterial standard strains. Pheophytin a exhibited antimicrobial action against all microorganisms tested.

resumo Sidastrum micranthum (A. St.-Hil.) Fryxell, pertencente à família Malvaceae, é conhecida no Brasil como "malva preta". A espécie é popularmente usada contra bronquite, tosse e asma, mostrando a relevância de conhecer melhor sua composição química. O estudo fitoquímico do extrato hexânico da espécie, utilizando técnicas cromatográficas, conduziu ao isolamento de seis compostos: o triterpeno isoarborinol, mistura de sitosterol e estigmasterol, sitosterol-3-O-β-D-glicopiranosídeo, feofitina a e de 132-hidroxi-(132-S)-feofitina a. A identificação estrutural destes compostos foi realizada com base em métodos espectroscópicos, tais como IV, RMN 1D e 2D (HOMOCOSY, HMQC, HMBC e NOESY). As substâncias isoladas de Sidastrum micranthum foram avaliadas quanto às suas atividades antimicrobianas in vitro, contra vinte cepas fúngicas e bacterianas. A feofitina a mostrou ação antimicrobiana contra todos os microrganismos testados.

Development and validation of a rapid turbidimetric assay to determine the potency of norfloxacin in tablets

Norfloxacin is one of the first commercially available (and most widely used) fluoroquinolone antibiotics. This paper reports the development and validation of a simple, sensitive, accurate and reproducible turbidimetric assay method to quantify norfloxacin in tablets formulations in only 4 hours. The bioassay is based on the inhibitory effect of norfloxacin upon the strain ofStaphylococcus epidermidis ATCC 12228 IAL 2150 used as test microorganism. The assay was performed 3x3 parallel lines like, three tubes for each concentration of reference substance and three tubes for each sample concentration. The results were treated statistically by analysis of variance and were found to be linear (r2 = 0.9999) in the selected range of 25-100 μg mL-1; precise (intra-assay: relative standard deviation (RSD) = 1.33%; inter-assay: RSD = 0.21%), accurate (100.74%) and robust with RSD lower than 4.5%. The student's t-test showed no statistically significant difference between the proposed turbidimetric method and an HPLC method previously validated. However the turbidimetric assay can be used as a valuable alternative methodology for the routine quality control of this medicine, complementary to other physical-chemical methods.

O norfloxacino foi a primeira fluorquinolona (e mais utilizada) disponível no mercado. Este trabalho divulga um novo desenvolvimento e validação de um método turbidimétrico simples, sensível, preciso e reprodutível para a quantificação de norfloxacino em comprimidos em apenas 4 horas. O bioensaio é baseado no efeito inibitório de norfloxacino sobre a cepa Staphylococcus epidermidis ATCC 12228 IAL 2150, utilizada como micro-organismo teste. O bioensaio foi efetuado através do delineamento de linhas paralelas 3x3, em que três tubos foram utilizados para a solução padrão e três tubos para as concentrações da amostra. Os resultados foram tratados estatisticamente pela análise de variância, apresentando coeficiente de correlação linear der2 = 0,9999, na faixa de 20 a 100 μg mL-1; precisão (intra-ensaio: desvio padrão relativo (RSD) 1,33%; inter-ensaio: RSD=0,21%), exatidão (100,74%) e robustez com RSD menor que 4,5%. O teste-tmostrou não haver diferença estatisticamente significativa entre o método turbidimétrico proposto e um método por HPLC previamente validado. No entanto, o ensaio turbidimétrico pode ser utilizado como método alternativo para o controle de qualidade de rotina para este antimicrobiano, como um complemento de outros métodos físico-químicos.

Pharmacokinetics and pharmacodynamics of antimicrobial drugs in intensive care unit patients.

Inappropriate use of antimicrobial drugs is responsible for therapeutic failures, increased mortality rates, and the emergence of resistance. Antimicrobial activity is determined by intrinsic pharmacokinetics/pharmacodynamics concepts. In critically ill patients, an inappropriate dosing regimen can be caused by the inability of an antimicrobial drug to reach adequate concentrations at the infection site owing to alterations in the drug's pharmacokinetics caused by pathophysiological changes. Understanding these concepts and changes in PK-PD parameters that occur in intensive care unit patients is crucial for the optimization of antimicrobial therapy in these patients.

Assessment of ion diffusion from a calcium hydroxide-propolis paste through dentin

This study evaluated the ability of ions from a non-alcoholic calcium hydroxide-propolis paste to diffuse through dentinal tubules. Thirty-six single-rooted bovine teeth were used. The tooth crowns were removed, and the root canals were instrumented and divided into 3 groups: Group 1 - calcium hydroxide-propylene glycol paste; Group 2 - calcium hydroxide-saline solution paste; Group 3 - calcium hydroxide-propolis paste. After the root canal dressings were applied, the teeth were sealed and placed in containers with deionized water. The pH of the water was measured after 3, 24, 72 and 168 hours to determine the diffusion of calcium hydroxide ions through the dentinal tubules. All of the pastes studied promoted the diffusion of calcium hydroxide ions through the dentinal tubules. Associating propolis to calcium hydroxide resulted in a pH increase, which occurred with greater intensity after 72 hours. The calcium hydroxide-propolis paste was able to diffuse in dentin.

Assessment of ion diffusion from a calcium hydroxide-propolis paste through dentin.

This study evaluated the ability of ions from a non-alcoholic calcium hydroxide-propolis paste to diffuse through dentinal tubules. Thirty-six single-rooted bovine teeth were used. The tooth crowns were removed, and the root canals were instrumented and divided into 3 groups: Group 1 - calcium hydroxide-propylene glycol paste; Group 2 - calcium hydroxide-saline solution paste; Group 3 - calcium hydroxide-propolis paste. After the root canal dressings were applied, the teeth were sealed and placed in containers with deionized water. The pH of the water was measured after 3, 24, 72 and 168 hours to determine the diffusion of calcium hydroxide ions through the dentinal tubules. All of the pastes studied promoted the diffusion of calcium hydroxide ions through the dentinal tubules. Associating propolis to calcium hydroxide resulted in a pH increase, which occurred with greater intensity after 72 hours. The calcium hydroxide-propolis paste was able to diffuse in dentin.

The effect of smoking on the bioavailability of metronidazole in plasma and saliva.

BACKGROUND: Cigarette smoking is considered to be a major risk factor for periodontal disease, and the antimicrobial agent metronidazole is commonly used for treatment of periodontitis. The authors evaluated the effect of cigarette smoking on the bioavailability of metronidazole in plasma and saliva. METHODS: Thirteen smokers and 13 nonsmokers received a single oral dose of 750 milligrams of metronidazole. Study personnel collected blood and saliva samples at baseline and at 0.5, 1, 1.5, 2, 4, 6, 8, 12, 24 and 48 hours after metronidazole administration. The authors quantified plasmatic and salivary metronidazole concentrations by means of high-performance liquid chromatography, and they determined the pharmacokinetic parameters and analyzed them statistically by using the Mann-Whitney test and nonpaired t test (α = 5 percent). RESULTS: The authors detected a significant reduction in plasmatic metronidazole concentrations in smokers at 1 hour, 1.5 hours and 2 hours compared with nonsmokers (P < .05). They also found a significant reduction in the maximum concentration in plasma in smokers as compared with that of nonsmokers (P < .05). The authors observed no statistically significant differences in the salivary concentration or pharmacokinetics between the two groups, however (P > .05). CONCLUSION: Cigarette smoking interfered with the bioavailability of metronidazole in plasma but not in saliva. Practice Implications. The clinical significance of these findings needs to be investigated further to verify the effectiveness of metronidazole in smokers.