Genotoxicity evaluation of a new phthalazine substituted ß-lactam derivative in human lymphocytes.

The aim of present study, to evaluate the genotoxic potential of 1-(4-(3,3-dimethyl-1,6-dioxo-2,3,4,6,11,13-hexahydro-1H-indazolo[1,2b] phthalazine-13yl)phenyl)-2-phenylazetidine-3-yl-acetate which was synthesised assuming that it may be a pharmaceutical raw material and found to inhibit human carbonic anhydrase I, II isozymes. To determine the genotoxic potential of this phthalazine substituted ß-lactam compound, chromosomal aberration (CA) and micronucleus (MN) tests were implemented in human peripheral blood lymphocytes. In these tests, lymphocyte cultures were treated with four concentrations (30, 15, 7.5, 3.75 µg/mL) of test compound and simultaneously with negative control (sterile distilled water), solvent control (DMSO) positive control (MMC). According to our results, CA frequencies were significantly increased in two high applied concentrations (30, 15 µg/mL) compared with negative and solvent control. MN frequencies were significantly increased in three applied concentrations (30, 15, 7.5 µg/mL) except lowest concentration (3.75 µg/mL) compared with solvent control. Mitotic indices were also affected by treatment with test compound. The obtained results provide evidence to demonstrate that new phthalazine substituted ß-lactam derivative can exert genotoxic and cytotoxic effects in peripheral human lymphocytes especially at high concentrations.

Hazard assessment of beta-lactams: Integrating in silico and QSTR approaches with in vivo zebrafish embryo toxicity testing.

Antibiotics have emerged as a well-known representative of pharmaceuticals and personal care products (PPCPs) by causing public health and environmental problems due to their potential toxicity. ß-lactams are the most commonly used antibiotics in the world. This study used zebrafish embryos to evaluate the toxicity of ß-lactams. The results showed that 23 ß-lactam compounds induced malformation and death in a concentration-response manner. Moreover, this study established and validated quantitative structure-toxicity relationship (QSTR) models for the toxicity of ß-lactams in zebrafish. These models performed well and fast in the prediction of the acute toxicity of ß-lactams. Structural interpretation indicated that the ß-lactam ring, the thiazolidine/dihydrothiazine rings, the side chains, and spatial configuration are the main factors responsible for the toxicity of ß-lactams. The results from our previous studies and this study also revealed that the potential biological risks caused by ß-lactams and their degradation products could not be ignored. This study provided important data for further environmental risk assessment of ß-lactams and regulatory purposes.

Penicillin causes non-allergic anaphylaxis by activating the contact system.

Immediate hypersensitivity reaction (IHR) can be divided into allergic- and non-allergic-mediated, while "anaphylaxis" is reserved for severe IHR. Clinically, true penicillin allergy is rare and most reported penicillin allergy is "spurious". Penicillin-initiated anaphylaxis is possible to occur in skin test- and specific IgE-negative patients. The contact system is a plasma protease cascade initiated by activation of factor XII (FXII). Many agents with negative ion surface can activate FXII to drive contact system. Our data showed that penicillin significantly induced hypothermia in propranolol- or pertussis toxin-pretreated mice. It also caused a rapid and reversible drop in rat blood pressure, which did not overlap with IgE-mediated hypotension. These effects could be countered by a bradykinin-B2 receptor antagonist icatibant, and consistently, penicillin indeed increased rat plasma bradykinin. Moreover, penicillin not only directly activated contact system FXII-dependently, but also promoted bradykinin release in plasma incubated-human umbilical vein endothelial cells. In fact, besides penicillin, other beta-lactams also activated the contact system in vitro. Since the autoactivation of FXII can be affected by multiple-factors, plasma from different healthy individuals showed vastly different amidolytic activity in response to penicillin, suggesting the necessity of determining the potency of penicillin to induce individual plasma FXII activation. These results clarify that penicillin-initiated non-allergic anaphylaxis is attributed to contact system activation, which might bring more effective diagnosis options for predicting penicillin-induced fatal risk and avoiding costly and inappropriate treatment clinically.

A QSAR-based mechanistic study on the combined toxicity of antibiotics and quorum sensing inhibitors against Escherichia coli.

Quorum sensing inhibitors (QSIs) have attracted increasing attention due to their potential roles as the antibiotic alternatives. The combination of QSIs and antibiotics in clinical use and their subsequent release into the environment may result in joint effects on the ecology and environment, which has not received enough concerns yet. In this study, eight potential QSIs and three types of commonly used antibiotics, i.e., sulfonamides (SAs), ß-lactams and tetracyclines (TCs), were investigated for their combined toxicity on Escherichia coli (E. coli). The QSAR models for the combined toxicity were constructed using the interaction energies between the chemicals and their target proteins as calculated by molecular docking. It was revealed that the SAs and QSIs presented either additive or antagonistic joint effects in the mixture toxicity test, while ß-lactams and TCs showed only antagonistic effects with the QSIs. The analysis on the coefficients in the QSAR models suggested that the QSIs in the mixtures were more involved in the interaction with the proteins than the antibiotics. This study will help better understand the risks of joint exposure to the antibiotics and QSIs, and provide a new perspective for the study of the combined toxicity mechanism.

Evaluation of the in vitro ocular toxicity of the fortified antibiotic eye drops prepared at the Hospital Pharmacy Departments / Evaluación de la toxicidad ocular in vitro de los colirios fortificados antibióticos elaborados en los Servicios de Farmacia Hospitalaria

The use of parenteral antibiotic eye drop formulations with non-marketed compositions or concentrations, commonly called fortified antibiotic eye drops, is a common practice in Ophthalmology in the hospital setting. The aim of this study was to evaluate the in vitro ocular toxicity of the main fortified antibiotic eye drops prepared in the Hospital Pharmacy Departments. We have conducted an in vitro experimental study in order to test the toxicity of gentamicin, amikacin, cefazolin, ceftazidime, vancomycin, colistimethate sodium and imipenem-cilastatin eye drops; their cytotoxicity and acute tissue irritation have been evaluated. Cell-based assays were performed on human stromal keratocytes, using a cell-based impedance biosensor system [xCELLigence Real-Time System Cell Analyzer (RTCA)], and the Hen’s Egg Test for the ocular irritation tests. All the eye drops, except for vancomycin and imipenem, have shown a cytotoxic effect dependent on concentration and time; higher concentrations and longer exposure times will cause a steeper decline in the population of stromal keratocytes. Vancomycin showed a major initial cytotoxic effect, which was reverted over time; and imipenem appeared as a non-toxic compound for stromal cells. The eye drops with the highest irritating effect on the ocular surface were gentamicin and vancomycin. Those antibiotic eye drops prepared at the Hospital Pharmacy Departments included in this study were considered as compounds potentially cytotoxic for the ocular surface; this toxicity was dependent on the concentration used (AU)

El uso de reformulaciones de antibióticos parenterales en forma de colirios de composición o concentraciones no comercializadas, comúnmente denominados colirios antibióticos reforzados, es una práctica habitual en oftalmología a nivel hospitalario. El objetivo del presente trabajo ha consistido en evaluar la toxicidad ocular in vitro de los principales colirios antibióticos reforzados elaborados en los Servicios de Farmacia Hospitalaria. Hemos realizado un estudio experimental in vitro para evaluar la toxicidad de los colirios de gentamicina, amikacina, cefazolina, ceftazidima, vancomicina, colistimetato de sodio e imipenem-cilastatina en el que se ha evaluado su citotoxicidad y la irritación tisular aguda. Los ensayos celulares se realizan sobre queratocitos estromales humanos, mediante la utilización de un sistema biosensor de impedancia celular [(xCELLigence Real-Time System Cell Analyzer (RTCA)] y los ensayos de irritación ocular mediante el ensayo Hen´s Egg Test. Todos los colirios, excepto vancomicina e imipenem, han mostrado un efecto citotóxico de concentración y tiempo dependiente, siendo las concentraciones más altas y los tiempos más prolongados los que provocan un descenso más pronunciado en la población de queratocitos estromales. La vancomicina muestra un importante efecto citotóxico inicial que revierte con el transcurso del tiempo y el imipenem se muestra como un compuesto no tóxico para las células estromales. Los compuestos con mayor efecto irritante para la superficie ocular son la gentamicina y la vancomicina. Los colirios antiinfecciosos elaborados en los Servicios de Farmacia Hospitalaria estudiados se muestran como compuestos potencialmente citotóxicos para la superficie ocular, siendo esta toxicidad dependiente de la concentración utilizada (AU)

Side effects of antibiotics on the intestinal microflora by PCR-DGGE.

Antibiotics are recommended for use in the treatment of infectious diseases, but the side effects have not been thoroughly investigated, especially on the intestinal tract. Fluoroquinolones, macrolides and ß-lactams were tested the side effects on the intestinal microbflora of mice in this study. The similarity and sequence analysis of the dominant bands for different drug administration periods were carried out by denaturing gradient gel electrophoresis (DGGE) profiles. The total amount of 16S rRNA gene increased after drug administration, the bacterial composition and structure could be divided into different clusters for different drug administration periods distinctly. This study revealed a significant change of bacterial composition of microflora from intestinal tract as antibiotics were applied to tested mice.

Juvenile toxicity study of faropenem medoxomil in beagle puppies.

We determined the toxicity of faropenem medoxomil (FPM) in neonatal/juvenile dogs following 28 days of administration. The puppies received vehicle or FPM beginning on Postnatal Day (PND) 22 at respective dose levels of 0, 100, 300, 600, or 1400 mg/kg-d (four daily doses (QID) of 25, 75, 150, or 350 mg/kg/dose), respectively, at a dose volume of 5 mL/kg/dose. Body weight, food consumption, clinical observation, clinical pathology, urine analysis and TK were evaluated. Body weight in males and kidney findings at 1400 mg/kg-d were considered adverse. Comparison of Day 27 TK values with Day 1 parameters showed a change in FPM pharmacokinetic behavior over time with an apparent increase in the rate of clearance characterized by a decrease in AUC(0-6) and T(max) values on Day 27 with little to no change in C(max) values. Based on these results, the No Observed Adverse Effect Level was 600 mg/kg-d.

Investigation of the sensitising and cross-sensitising potential of textile dyes and beta-lactam antibiotics using a biphasic mice local lymph node assay.

We used a modified protocol of the murine local lymph node assay (LLNA) to study the cross-sensitising potential of (a) textile dye disperse yellow 3 and its metabolite 2-amino-p-cresol, (b) two antibiotics, penicillin G and cefotiam. The test substances were applied in a biphasic manner, i.e. first on the shaved skin of the back followed by application on the dorsal side of the ears after 2 weeks. The end-points analysed included thickness and weight of an ear-biopsy, weight and cell number of the draining lymph node, and lymphocyte cell surface markers analysed by flow-cytometry. Disperse yellow 3 and its metabolite significantly altered the various end-points at both the tested concentrations (0.5 and 1%), thus demonstrating the sensitising potential of the two substances. The cross-sensitisation study showed significant modulation in the tested variables in the treated group as compared to the control, signifying cross-sensitisation potential of the two substances. Penicillin G and cefotiam showed significant changes in various end-points, pointing towards their sensitising potential. However, even at 50% concentration of the beta-lactams no significant change in any end-point indicating absence of cross-reactivity of the antibiotics was noticed. We conclude that a biphasic, modified protocol of the LLNA is a suitable approach to test for a cross-reactivity potential of two related compounds.

Antibacterial and toxicological evaluation of beta-lactams synthesized by immobilized beta-lactamase-free penicillin amidase produced by Alcaligenes sp.

Search for anti-beta-lactamase and synthesis of newer penicillin were suggested to overcome resistance to penicillin in chemotherapy. It was found that clavulanic acid, an ant-beta-lactamase was ineffective due to its structural modification by bacteria. Thus, there is a need for the synthesis of newer pencillins. Retro-synthesis was inspired by the success of forward reaction i.e.conversion of penicillin G to 6-aminopenicillanic acid (6-APA) by biological process. In the present study a better enzymatic method of synthesis of newer pencillin by a beta-lactamase-free penicillin amidase produced by Alcaligenes sp. is attempted. Antibacterial and toxicological evaluation of the enzymatically synthesized beta-lactams are reported. Condensation of 6-APA with acyl donor was found to be effective when the reaction is run in dimethyl formamide (DMF 50% v/v) in acetate buffer (25 mM pH 5.0) at 37 degrees C. Periplasm entrapped in calcium alginate exihibited the highest yield (approximately 34%) in synthesis. The minimum inhibitory concentration of the synthetic products against Staphylococcus aureus and Salmonella typhi varied between 20-80 microg/ml. Some of the products exhibited antibacterial activity against enteric pathogens. It was interesting to note that product A was potent like penicillin G. LD50 value of three products (product A, B and C) was more than 12 mg/kg. Furthermore, these synthetic beta-lactams did not exihibit any adverse effect on house keeping enzymes viz., serum glutamate oxalacetate-trans-aminase, serum glutamate pyruvate -trans-aminase, acid phosphatase, alkaline phosphatase of the test animals. The hematological profile (RBC and WBC) of the test animals also remained unaffected.

Neurotoxicity induced by beta-lactam antibiotics: from bench to bedside.

Central nervous system toxicity following administration of beta-lactam antibiotics, of which penicillin is the prototype, is a potential cause of morbidity and mortality. In recent years, important advances have been made in the pathogenesis of antibiotic-related neurotoxicity. This review focuses on the experimental and clinical aspects of neurotoxicity caused by beta-lactam antibiotics. The purpose is to provide an update on the pathogenesis, mechanism, and clinical manifestations of the neurotoxicity, along with an overview of the relationship between antibiotic structure and convulsive action. In particular, some of the prevailing ideas about pathogenesis are highlighted, including theories of the mechanism of pathogenicity. A better understanding of antibiotic-related neurotoxicity, as derived from animal models and human clinical experience, would be of value in facilitating more efficient and safer use of antimicrobial compounds.

Nocardicin A, a new monocyclic beta-lactam antibiotic V. In vivo evaluation.

Nocardicin A is a new monocyclic beta-lactam antibiotic which provides a potent therapeutic effect in mice experimentally infected with gram-negative bacilli. When given subcutaneously to mice, the therapeutic effect of the drug was stronger than had been anticipated from in vitro studies. Nocardicin A was more potent in therapeutic effect than carbenicillin against infections due to Pseudomonas aeruginosa, Proteus mirabilis, Pr. vulgaris, Pr. rettgeri and Pr. inconstans, and was similar in effect to carbenicillin against infections due to Escherichia coli in mice. In addition, nocardicin A proved to be active against infections due to Serratia marcescens and other organisms resistant to beta-lactam antibiotics. When nocardicin A was given subcutaneously to mice, blood and hepatic levels of the drug were higher than those of carbenicillin.