Agar/κ-carrageenan/montmorillonite nanocomposite hydrogels for wound dressing applications.

In this study, agar/κ-carrageenan/montmorillonite (MMT) hydrogels were prepared to examine their usability as wound dressing materials and to see the effect of MMT amount on some properties of agar/κ-carrageenan hydrogel materials. Hydrogels were characterized by SEM-EDX, TEM and DSC analyses. By increasing the MMT content within hydrogel matrix from 0% to 5%, the decomposition temperature of the hydrogel material was increased from 256.6 °C to 262.1 °C. Swelling amount of hydrogels in d-glucose solution (2682%) was found to be much higher compared with other physiological solutions such as physiological saline solution (937%), synthetic urine solution (746%) and simulated wound fluid (563%). The release studies of analgesic lidocaine hydrochloride (LDC) and antibiotic chloramphenicol (CLP) drugs from hydrogel systems demonstrated that the release amount of LDC and CLP from hydrogels could be controlled by MMT amount within hydrogel matrix. The concentrations of drugs within hydrogel sample stored at 4 °C for 6 months did not exhibit a significant change. Hydrogel materials containing CLP exhibited good antibacterial activity against E. coli and S. aureus. Cytotoxicity test results indicated that hydrogels were biocompatible with MG-63 cells. The ultimate compressive stress of agar/κ-carrageenan hydrogel with LDC and CLP and agar/κ-carrageenan/MMT hydrogel including 5% MMT with LDC and CLP was measured as 38.30 kPa and 47.70 kPa, respectively. The experimental results revealed that prepared agar/κ-carrageenan and agar/κ-carrageenan/MMT hydrogels have great potential for wound care applications.

Chloramphenicol/sulfobutyl ether-ß-cyclodextrin complexes in an ophthalmic delivery system: prolonged residence time and enhanced bioavailability in the conjunctival sac.

Objective: Conventional chloramphenicol (CHL) eye drops are widely used anti-infection formulations for acute bacterial conjunctivitis. However, the therapeutic effects are limited by insufficient concentration in the conjunctival sac. Hence, the objective of this study is to formulate and develop novel CHL eye drops with improved topical concentrations by increasing the solubility and decreasing the transcorneal penetration. Research design and methods: CHL was included in the sulfobutyl ether-ß-cyclodextrin (SBE-ß-CD) using the freeze-drying method. Eye drops containing CHL/SBE-ß-CD complexes were prepared and evaluated for in vitro and in vivo studies. Results: The formation of CHL/SBE-ß-CD inclusion was confirmed by DSC, XRD, NMR, and SEM. The aqueous solubility of CHL was significantly enhanced, and the drug transcorneal penetration was inhibited after inclusion. The CHL/SBE-ß-CD displayed sustained release profiles. The tear fluid elimination kinetic study showed that the CHL/SBE-ß-CD eye drops had better ability to prolong the residence time, and significantly increase CHL concentration in the conjunctival sac. Besides, it was shown that CHL/SBE-ß-CD eye drops were nonirritating to rabbits' eyes. Conclusions: The SBE-ß-CD inclusions offer a potential alternative strategy for ocular administration of poorly water-soluble drugs in the conjunctival sac.

Construction of a simple evaluation system for the intestinal absorption of an orally administered medicine using Bombyx mori larvae.

Human intestinal absorption is estimated using a human colon carcinoma cell line (Caco-2) cells from human colorectal adenocarcinoma, intestinal perfusion, or a mammalian model. These current evaluation systems are limited in their ability to estimate human intestinal absorption. In addition, in vivo evaluation systems using laboratory animals such as mice and rats entail animal ethics problems, and it is difficult to screen compounds on a large scale at the drug discovery stage. Thus, we propose the use of Bombyx mori larvae for evaluation of intestinal absorption of compounds as an alternative system in this study. First, to compare the characteristics among Caco-2 cells, human intestine, and B. mori larval midgut, we analyzed their RNA-seq data, and we found 26 drug transporters common to humans and B. mori. Next, we quantitatively developed an oral administration technique in B. mori and established a method using silkworm B. mori larvae that can easily estimate the intestinal permeability of compounds. Consequently, we could determine the dose and technique for oral administration in B. mori larvae. We also developed a B. mori model to evaluate the intestinal permeability of orally administered. Our constructed evaluation system will be useful for evaluating intestinal permeability in medical drug development.

Integrated Genomic and Proteomic Analyses of High-level Chloramphenicol Resistance in Campylobacter jejuni.

Campylobacter jejuni is a major zoonotic pathogen, and its resistance to antibiotics is of great concern for public health. However, few studies have investigated the global changes of the entire organism with respect to antibiotic resistance. Here, we provide mechanistic insights into high-level resistance to chloramphenicol in C. jejuni, using integrated genomic and proteomic analyses. We identified 27 single nucleotide polymorphisms (SNPs) as well as an efflux pump cmeB mutation that conferred modest resistance. We determined two radical S-adenosylmethionine (SAM) enzymes, one each from an SNP gene and a differentially expressed protein. Validation of major metabolic pathways demonstrated alterations in oxidative phosphorylation and ABC transporters, suggesting energy accumulation and increase in methionine import. Collectively, our data revealed a novel rRNA methylation mechanism by a radical SAM superfamily enzyme, indicating that two resistance mechanisms existed in Campylobacter. This work provided a systems biology perspective on understanding the antibiotic resistance mechanisms in bacteria.

Formulation optimization of palm kernel oil esters nanoemulsion-loaded with chloramphenicol suitable for meningitis treatment.

Palm kernel oil esters nanoemulsion-loaded with chloramphenicol was optimized using response surface methodology (RSM), a multivariate statistical technique. Effect of independent variables (oil amount, lecithin amount and glycerol amount) toward response variables (particle size, polydispersity index, zeta potential and osmolality) were studied using central composite design (CCD). RSM analysis showed that the experimental data could be fitted into a second-order polynomial model. Chloramphenicol-loaded nanoemulsion was formulated by using high pressure homogenizer. The optimized chloramphenicol-loaded nanoemulsion response values for particle size, PDI, zeta potential and osmolality were 95.33nm, 0.238, -36.91mV, and 200mOsm/kg, respectively. The actual values of the formulated nanoemulsion were in good agreement with the predicted values obtained from RSM. The results showed that the optimized compositions have the potential to be used as a parenteral emulsion to cross blood-brain barrier (BBB) for meningitis treatment.

Ocular penetration of topical antibiotics: study on the penetration of chloramphenicol, tobramycin and netilmicin into the anterior chamber after topical administration.

BACKGROUND: To compare penetration in the aqueous humour of topically applied antibiotics. DESIGN: Randomized prospective study, Department of Ophthalmology, University of Perugia, Italy PARTICIPANTS: Patients undergoing cataract surgery. METHODS: One hundred twenty-two patients were included: 14 received one drop of chloramphenicol suspension; 12 one application of chloramphenicol gel; 11 one drop of netilmicin suspension; 13 one drop of tobramycin suspension; 37 repeated instillations of chloramphenicol suspension every 10 min for a total of four drops; and 35 repeated instillations of chloramphenicol gel every 10 min for a total of four drops. Samples were taken immediately before surgery from the anterior chamber in order to determine the antibiotic by means of high-performance liquid chromatography. Samples were taken 45-190 min after the eye drops were instilled. MAIN OUTCOME MEASURES: Intraocular penetration of chloramphenicol, netilmicin and tobramicyn. RESULTS: After a single administration, netilmicin and tobramycin were undetectable, whereas the chloramphenicol suspension reached a mean concentration of 0.23 ± 0.21 µg/mL, and the chloramphenicol gel a mean concentration of 0.13 ± 0.14 µg/mL. After repeated administrations, the mean concentrations of the chloramphenicol suspension and gel were 0.60 ± 0.26 µg/mL and 0.58 ± 0.18 µg/mL, respectively. CONCLUSIONS: Tobramycin and netilmicin do not reach detectable concentrations, whereas chloramphenicol, after multiple administrations, reaches concentrations that are effective against Haemophilus influenzae and Haemophilus parainfluenzae, Legionella pneumophila, Moraxella catarrhalis, Neisseria meningitidis, Pasteurella multocida and Streptococcus pneumoniae. This means that chloramphenicol can be rationally used in the prophylaxis and treatment of infections supported by sensitive germs.

Inhibitors of antibiotic efflux pump in resistant Enterobacter aerogenes strains.

Enterobacter aerogenes, a nosocomial pathogen, is frequently exhibiting multidrug resistance mechanisms associated with a change in membrane permeability. In clinical isolates, active efflux plays a prominent role in antibiotic resistance. We report here the effect of three unrelated compounds that are able to restore a noticeable antibiotic susceptibility to resistant strains. The targeting of various parameters which contribute to the efficacy of the efflux mechanism, such as energy, flux selectivity, or functional assembly of the membrane complex, increases the intracellular chloramphenicol concentration in resistant isolates.

Consideraciones generales sobre el uso de agentes antimicrobianos en pacientes hepáticos / General remarks: antimicrobial agents use in hepatic patients

El hígado juega un papel fundamental en el metabolismo de las drogas, incluyendo los antimicrobianos. En los pacientes con enfermedad hepática, se deben monitorizar cuidadosamente los efectos adversos y toxicidad de estos medicamentos. En este artículo se analizan los aspectos del metabolismo de los antimicrobianos, particularmente relacionados a los cambios farmacocinéticos en los pacientes hepáticos. Además, se dan algunas recomendaciones prácticas sobre su uso en estos pacientes

Predición bayesiana de las concentraciones séricas de clorafenicol en niños con sepsis y desnutrición / Evaluation on the performance of bayesian adaptive control system to forecast the chloramphenicol serum concentrations in pediatric patients with sepsis and malnutrition

Objetivo. Validar los parámetros farmacocinéticos de cloranfenicol en pacientes pediátricos con sepsis y desnutrición (PPSD) por medio de un programa de predicción bayesiano para cloranfenicol en PPSD. Lugar. Hospital Pediátrico de Enseñanza de Tercer Nivel. Pacientes. Quince PPSD y diez pacientes pediátricos con sepsis sin desnutrición (PPSN), que recibieron tratamiento con cloranfenicol. Método y resultados principales. En la primera parte del estudio, los expedientes clínicos de 10 PPSD y 10 PPSN quienes habían recibido tratamiento con cloranfenicol fueron revisados. Los parámetros farmcocinéticos poblacionales para cada grupo fueron estimados por medio de un algoritmo no paramétrico de maximización de expectativas (NPEM). En la segunda parte, cinco pacientes independientes con indicadores similares de desnutrición que recibieron cloranfenicol fueron utilizados para probar el desempeño predictivo de los modelos poblacionales, utilizados éstos como distribución a priori en un programa de control adaptado bayesiano. Las concentraciones séricas de cloranfenicol predichas por el método bayesiano fueron comparadas con las concentraciones observadas. El modelo específico para PPSD permitió pronosticar las concentraciones pico y valle de cloranfenicol con menor sesgo y con una mayor precisión, comparado con el modelo poblacional de PPSN. Conclusiones. Estos datos indican que la farmacocinética de cloranfenicol en PPSD puede predecirse con un sesgo mínimo y una buena precisión utilizando un programa bayesiano, permitiendo así, un mejor control sobre el grado de exposición a esta droga y con el beneficio económico adicional de requerir de un número limitado de muestras por paciente

Antibacterial and sebosuppressive efficacy of a combination of chloramphenicol and pale sulfonated shale oil. Multicentre, randomized, vehicle-controlled, double-blind study on 91 acne patients with acne papulopustulosa (Plewig and Kligman's grade II-III).

In a 3-armed, multicentre, randomized, double-blind, vehicle-controlled study involving 91 patients with acne papulopustulosa, Plewig's grade II-III, evidence could be provided of a significant reduction of the propionibacteria as well as a subosuppressive effect (squalene reduction) under a combination of 1% chloramphenicol (CAS 56-75-7) and 0.5% pale sulfonated shale oil versus the alcoholic vehicle (1-2 ml twice daily). Likewise, monotherapy with chloramphenicol resulted in a significant reduction in bacteria compared to the vehicle. The combination therapy was superior to the monotherapy with regard to the sebosuppressive effects. Based on a kinetics test carried out for a total of 2 h, a clinically relevant percutaneous absorption of chloramphenicol was ruled out. The chloramphenicol serum level was between < 5.0 microgram/l to 180 microgram/l (average 25 micogram/l). This is important because with systemic application (peroral, i.v.), the therapeutic chloramphenicol level is > 25 mg/l (25,000 microgram 1). None of the blood count and serum parameters were pathologically changed in a clinically relevant way before and after the therapy. An induction of resistance against chloramphenicol in the propionibacteria could be excluded. No adverse events and side effects occurred. The topical therapy of acne papulopustulosa with chloramphenicol as a monosubstance or in combination with pale sulfonated shale oil represents an effective and safe local antibiotic treatment possibility.

The myelotoxicity of chloramphenicol: in vitro and in vivo studies: II: In vivo myelotoxicity in the B6C3F1 mouse.

1. Chloramphenicol continues to be widely used in many parts of the world despite its known haematotoxicity. Until now, elucidation of the mechanisms involved and any attempt at amelioration of the toxic effects have been hampered by the lack of an animal model. 2. In this study neither acute nor chronic administration of chloramphenicol as its succinate ester in the drinking water produced anaemia in mice as assessed by changes in peripheral blood parameters. 3. Chloramphenicol could not be detected in the bone marrow when the antibiotic was administered either in the drinking water or by gavage, although it was detected in the serum. 4. In marrow taken from mice after chloramphenicol succinate administration and cultured in vitro, depression of the differentiation of immature committed erythroid progenitors occurred 15 min after administration of the antibiotic by gavage. However, recovery was beginning to occur at 48 h after administration of chloramphenicol succinate at 50 and 200 mg/kg and this was then followed by an 'overshoot' response at the higher dose. A toxic effect was therefore achieved in the bone marrow but this was probably masked in the peripheral blood by enhanced proliferation. 5. Morphological evidence of apoptosis was seen in erythroid and myeloid precursors in mice treated with 200 mg/kg. 6. The data suggest that the effect of chloramphenicol was at the differentiation stage of the committed marrow progenitor cells rather than at the replication stage of the stem cells and therefore this response appears to mimic the reversible bone marrow depression seen in the treated patient.

In vivo degradation and release kinetics of chloramphenicol-loaded poly(D,L)-lactide sponges.

Poly(d,l)-lactide (PDLLA) homopolymer, with an average molecular weight of 20,000 daltons, was produced by the ring-opening polymerization of d,l-lactide in the presence of SnCl(2).2H(2)O as the catalyst. The PDLLA sponges loaded with chloramphenicol were prepared by a solvent evaporation technique. The drug loadings achieved were 14.84 and 25.23 mg for the PDLLA sponges with 35 and 70 mg total weights, respectively. These sponges were implanted in Wistar rats, and in vivo degradation, drug release, and tissue reactions were followed. The PDLLA sponges carrying no drug degraded with time linearly. Almost 80% of the sponges were degraded in about 180 days. While the drug-loaded PDLLA sponges were degraded much faster in 4 weeks (about 35% of the matrix was degraded), then the degradation slowed down significantly. Drug release from the sponges was parallel to the degradation. Almost 60% of the loaded drug released in 4 weeks. There were no acute inflammatory reactions in the initial period, either for the plain or for the drug-loaded PDLLA sponges. Macrophages and multinuclear giant cells start to appear after 7 days of implantation. The fibroblastic activity also started after the same period. After that, there were decreases in the number of some cells (neutrophils, lymphocytes, and macrophages), while multinuclear giant cells and fibroblastic activities gradually increased. Granulation tissue started at about 1 month, and new connective tissue was gradually formed until 180 days of implantation. There were significant numbers of inflammatory cells after 60 days, which were replaced by fibroblasts after 180 days. There was almost no significant neovascularization after 180 days, but implant fragmentation gradually increased (which slows the degradation) with time. It was concluded that this novel drug release sponge may be safely and effectively used as an active soft tissue-filling material.

Identificación de especies de enterococcus en muestras clínicas y susceptibilidad a agentes antimicrobianos / Identification of enterococcus species from clinical samples and susceptibility to antimicrobial agents

The genus enterococcus has 12 species of which, E faecalis and E faecium are most important in human infections. A progressive resistance to penicillin and ampicillin has been detected in these species. The aim of this work was to identify Enterococcus species isolated in a hospital and to study their antimicrobial susceptibility. We studied 209 Enterococcus species coming from patients admitted to a public hospital. Their susceptibility to penicillin, ampicillin, imipenem, vancomycin, tetracycline, chloramphenicol, ciprofloxacin, gentamycin and streptomycin was determined with the agar dilution technique. Eighty seven percent of species were E faecalis and 7,1 percent were E fecium, other isolated species were E hirae, E casseliflaws, E avium, E solitarius and E faecalis variant. 38 percent of these species were isolated from the urinary tract, 22 percent from the skin and 14 percent from surgical wounds. All E faecalis species were susceptible to penicillin, ampicillin, imipenem and vancomycin; 27,3 percent were susceptible to tetracycline, 54,7 percent to chloramphenicol and 80 percent to ciprofloxacin. Seventy three percent of E faecium species were susceptible to penicillin, 80 percent to ampicillin and 60 percent to imipenem. 62 percent of E faecalis and 42.4 percent of E faecium were resistant to streptomycin. It is concluded that the correct identification of Enterococcus species has therapeutic implications

Chloramphenicol toxicity.

Although high serum concentrations of chloramphenicol are related to toxicity, as shown experimentally and during treatment, the mechanism of toxicity remains unclear. Published work suggests that relatively minor metabolites may be causally related to toxic reactions in vitro and some of these metabolites have been detected in sera from treated patients. It is possible that all the major toxic manifestations of chloramphenicol may be explained by attack by free radicals. Depletion in compounds acting as cellular antioxidants, such as glutathione and vitamin E, may conceivably increase the vulnerability of an individual to chloramphenicol toxicity, while supplementation with an antioxidant might protect against it. Research into the metabolism of chloramphenicol and into the mechanism of its toxicity has declined since early work in the 1950s and 1960s, but its continuing use worldwide means that there is justification for renewed interest in the toxicology of this useful antibiotic.

Evaluation of intraosseous vs intravenous antibiotic levels in a porcine model.

OBJECTIVES: To compare intraosseous vs intravenous routes of administration and their effects on serum levels of four antibiotics in an animal model. DESIGN: Prospective controlled study comparing two routes of drug administration. SETTING: Research laboratories of a large pharmaceutical company. PARTICIPANTS: Twenty male and female domestic swine weighing 10 to 20 kg. INTERVENTIONS: The animals were anesthetized and treated with controlled ventilation. The animals were divided into one of four groups: (1) intravenous and intraosseous cefotaxime sodium (50 mg/kg), (2) intravenous and intraosseous chloramphenicol sodium succinate (25 mg/kg), (3) intravenous and intraosseous vancomycin hydrochloride (15 mg/kg), or (4) intravenous and intraosseous tobramycin sulfate (2.5 mg/kg). There was a 24-hour clearance period for groups 1 and 2 and a 48-hour clearance period for groups 3 and 4. Serum drug levels were measured at 1, 15, 30, 45, 60, 90, and 120 minutes after intravenous and intraosseous administration of the respective antibiotics. Control and treated tibias were sampled for drug levels at the end of the experiment. MEASUREMENTS AND MAIN RESULTS: - Peak serum concentrations for intravenously administered antibiotics were within the therapeutic range. Peak serum levels after intravenous and intraosseous administration were 102 and 82 mg/L, respectively for cefotaxime; 13.9 and 6.3 mg/L, respectively, for chloramphenicol; 24.5 and 3.8 mg/L, respectively, for vancomycin; and 7.1 and 1.3 mg/L, respectively, for tobramycin. CONCLUSIONS: Cefotaxime may be administered intraosseously when intravenous access is not possible. We cannot recommend chloramphenicol or vancomycin for intraosseous administration, because serum levels were not comparable with those following intravenous administration. Findings with tobramycin suggested a lack of achievement of serum levels comparable with those following intravenous administration.