75 research outputs found
Impact of three ampicillin dosage regimens on selection of ampicillin resistance in Enterobacteriaceae and excretion of blaTEM genes in swine feces
The aim of this study was to assess the impact of three ampicillin dosage regimens on ampicillin resistance among Enterobacteriaceae recovered from swine feces using phenotypic and genotypic approaches. Phenotypically, ampicillin resistance was determined from the percentage of resistant Enterobacteriaceae and MICs of E. coli isolates. The pool of ampicillin resistance genes was also monitored by quantification of blaTEM genes, which code for the most frequently produced ÎČ-lactamases in Gram-negative bacteria, using a newly-developed real-time PCR assay. Ampicillin was administered intramuscularly and by oral route to fed or fasted pigs for 7 days at 20 mg/kg. The average percentage of resistant Enterobacteriaceae before treatment was between 2.5% and 12% and blaTEM genes quantities were below 107 copies/g of feces. By days four and seven, the percentage of resistant Enterobacteriaceae exceeded 50% in all treated groups, with some highly resistant strains (MIC>256”g/mL). In the control group, blaTEM genes quantities fluctuated between 104 - 106 copies/g of feces, whereas they fluctuated between 106-108 and 107-109 copies/g of feces for intramuscular and oral routes, respectively. Whereas phenotypic evaluations did not discriminate between the three ampicillin dosage regimens, blaTEM genes quantification was able to differentiate between the effects of two routes of ampicillin administration. Our results suggest that fecal blaTEM genes quantification provides a sensitive tool to evaluate the impact of ampicillin administration on the selection of ampicillin resistance in the digestive microflora and its dissemination in the environment
Assessment of the genotoxicity of quinolone and fluoroquinolones contaminated soil with the Vicia faba micronucleus test
The genotoxicity of quinolone and fluroquinolones was assessed using the micronucleus (MN) test on Viciafaba roots by direct contact exposure to a solid matrix. Plants were exposed to quinolones (nalidixic acid) and fluoroquinolones (ciprofloxacin and enrofloxacin) alone or mixed with artificially contaminatedsoils. Four different concentrations of each of these antibiotics were tested (0.01, 0.1, 1 and 10 mg/Kg) for nalidixic acid and (0.005, 0.05, 0.5 and 5 mg/Kg) for ciprofloxacin and enrofloxacin. These antibiotics were also used in mixture. Exposure of Vicia faba plants to each antibiotic at the highest two concentrations showed significant MN induction. The lowest two concentrations had no significant genotoxic effect. The mixture of the three compounds induced a significant MN induction whatever the mixture tested, from 0.02 to 20 mg/Kg. The results indicated that a similar genotoxic effect was obtained with the mixture at 0.2 mg/Kg in comparison with each molecule alone at 5â10 mg/Kg. Data revealed a clear synergism of these molecules on Vicia faba genotoxicity
Pharmacokinetics and pharmacodynamics of a therapeutic dose of unfractionated heparin (200 U/kg) administered subcutaneously or intravenously to healthy dogs
Objectives: To evaluate the effects of 200 U/kg of sodium unfractionated heparin (UFH) on coagulation times in dogs after IV and SC administration and to compare these effects with plasma heparin concentrations assessed by its anti Xa activity. Methods: 200 U/kg of UFH were administered Intravenously (IV) and Subcutaneously (SC) to five healthy adult Beagle dogs with a wash out period of at least 3 days. Activated Partial Thromboplastin Time (APTT), Prothrombin Time (PT) and plasma anti-factor Xa (aXa) activity were determined in serial blood samples. Results: After IV injection, PT remained unchanged except for a slight increase in one dog; APTT was not measurable (> 60 s) for 45 to 90 min, then decreased regularly and returned to baseline values between 150 and 240 min. High plasma heparin concentrations were observed (C max = 4.64±1.4 aXa U/mL) and decreased according to a slightly concave-convex pattern on a semi-logarithmic curve but returned to baseline slightly more slowly (t240 to t300 min). After SC administration, APTT was moderately prolonged (mean±SD prolongation: 1.55±0.28 x APTT t0, range [1.35-2.01]) between 1 and 4 hours after administration. Plasma anti-factor Xa activity reached a maximum of 0.56±0.20 aXa U/mL, range: [0.42 - 0.9] after 132±26.8 min and this lasted for 102±26.8 min. Heparin concentrations were grossly correlated to APTT; prolongation of APTT of 120 to 160% corresponded to plasma heparin concentrations range of 0.3-0.7 aXa U/mL, considered as the therapeutic range in human medicine. Conclusions: As in human, pharmacokinetic of UFH in dogs is non linear. Administration of 200 U/kg of UFH SC in healthy dogs results in sustained plasma heparin concentrations in accordance with human recommendations for thrombosis treatment or prevention, without excessively increased bleeding risks. In these conditions, APTT can be used as a surrogate to assess plasma heparin concentrations. This has to be confirmed in diseased animals
Authors' Reply to Coste et al.: "LevothyroxÂź New and Old Formulations: Are they Switchable for Millions of Patients?"
"Authors'Reply to Coste et al"International audienc
Why Were More Than 200 Subjects Required to Demonstrate the Bioequivalence of a New Formulation of Levothyroxine with an Old One?
At the request of French Regulatory Authorities, a new formulation of LevothyroxÂź was licensed in France in 2017, with the objective of avoiding the stability deficiencies of an existing licensed formulation. Before launching the new formulation, an average bioequivalence (ABE) trial was conducted, having enrolled 204 subjects and selected for interpretation a narrow a priori bioequivalence range of 0.90â1.11. Bioequivalence was concluded. In a previous publication, we questioned the ability of an ABE trial to guarantee the switchability within patients of the new and old levothyroxine formulations. It was suggested that the two formulations should be compared using the conceptual framework of individual bioequivalence. The present paper is a response to those claiming that, despite the fact that ABE analysis does not formally address the switchability of the two formulations, future patients will nevertheless be fully protected. The basis for this claim is that the ABE study was established in a large trial and analyzed using a stringent a priori acceptance interval of equivalence. These claims are questionable, because the use of a very large number of subjects nullifies the implicit precautionary intention of the European guideline when, for a Narrow Therapeutic Index drug, it recommends shortening the a priori acceptance interval from 0.80â1.25 to 0.90â1.11
LevothyroxÂź new and old formulations: are they switchable for millions of patients?
International audienceIn France, more than 2.5 million patients are currently treated with levothyroxine, mainly as the marketed product Levothyrox Âź. In March 2017, at the request of French authorities, a new formulation of Levothyrox Âź was licensed, with the objective of avoiding stability deficiencies of the old formulation. Before launching this new formulation, an average bioequivalence trial, based on European Union recommended guidelines, was performed. The implicit rationale was the assumption that the two products, being bioequivalent, would also be switchable, allowing substitution of the new for the old formulation, thus avoiding the need for individual calibration of the dosage regimen of thyroxine, using the thyroid-stimulating hormone level as the endpoint, as required for a new patient on initiating treatment. Despite the fact that both formulations were shown to be bioequivalent, adverse drug reactions were reported in several thousands of patients after taking the new formulation. In this opinion paper, we report that more than 50% of healthy volunteers enrolled in a successful regulatory average bioequivalence trial were actually outside the a priori bioequivalence range. Therefore, we question the ability of an average bioequivalence trial to guarantee the switchability within patients of the new and old levothyroxine formulations. We further propose an analysis of this problem using the conceptual framework of individual bioequivalence. This involves investigating the bioavailability of the two formulations within a subject, by comparing not only the population means (as established by average bioequivalence) but also by assessing two variance terms, namely the within-subject variance and the variance estimating subject-by-formulation interaction. A higher within individual variability for the new formulation would lead to reconsideration of the appropriateness of the new formulation. Alternatively, a possible subject-by-formulation interaction would allow a judgement on the ability, or not, of doctors to manage patients effectively during transition from the old to the new formulation
Léchage entre congénÚres et antiparasitaires en [i]pour-on[/i].
DâaprĂšs les rĂ©sultats dâune sĂ©rie dâessais publiĂ©s ces 10 derniĂšres annĂ©es par des Ă©quipes de pharmacologues et de parasitologues toulousains, il apparaĂźt que le lĂ©chage peut ne pas affecter lâefficacitĂ© instantanĂ©e dâune lactone macrocyclique administrĂ©e en pour-on chez un bovin ainsi spoliĂ© dâune partie de sa dose, du moins dans les conditions expĂ©rimentales testĂ©e. Toutefois, une activitĂ© anthelminthique extrĂȘmement variable est dĂ©tectable chez des animaux en contact (lĂ©cheurs) normalement non traitĂ©s. Les consĂ©quences de ce phĂ©nomĂšne sont envisagĂ©es sur lâĂ©mergence de rĂ©sistances (y compris indirectes : par ineffi cacitĂ© de stratĂ©gies de lutte de type ârefugeâ) et sur la mĂ©thodologie des Ă©tudes de bioĂ©quivalence entre lactones macrocycliques en pour-on
Le concept « One Health » en antibiorésistance et les flux de gÚnes
Colloque « Pour des aliments sains : savoir maĂźtriser les risques en alimentation » Ă Toulouse le 28 novembre 2012.National audienceAntimicrobial resistance is a global concern to public health due to multidrug-resistant bacteria and to the lack of development of novel antibiotics. Evolution trends to antimicrobial resistance are directly related to the powerful adaptation abilities of bacteria. Moreover, bacteria have a large set of genetic weapons implicated in the acquisition, expression and spread of antimicrobial resistance genes. The shared use of antibiotics in Humans as well as in animals is a growing public health concern. Human and animal infectious diseases are so closely interlinked in a common environment, in which antimicrobials are shared that the One World - One Medicine - One Health concept fully applies to tackle the growing problems of antibiotic resistance. The rational and prudent use of antibiotics must apply worldwide in all fields to warrant the durable effectiveness of this valuable and limited drug class in the future.La rĂ©sistance aux antibiotiques acquise par le monde bactĂ©rien est un enjeu majeur de santĂ© publique en raison de la multirĂ©sistance et de lâabsence dâantibiotiques nouveaux. LâinquiĂ©tude est telle quâun retour Ă lâĂšre dâavant les antibiotiques pourrait ĂȘtre imaginĂ© si rien nâest fait. LâĂ©volution des bactĂ©ries vers la rĂ©sistance semble Ă ce jour inĂ©vitable en raison des capacitĂ©s gĂ©nĂ©rales dâadaptation des bactĂ©ries. De plus, les bactĂ©ries disposent dans leur gĂ©nome dâun arsenal gĂ©nĂ©tique spĂ©cialisĂ© dans lâacquisition, lâexpression et la diffusion des gĂšnes de rĂ©sistance. Lâenjeu de santĂ© publique sâest donc nouĂ© autour de lâusage partagĂ© des antibiotiques chez lâHomme comme chez lâanimal. Pour garantir globalement la santĂ© publique il est crucial de prĂ©server durablement lâefficacitĂ© de ces mĂ©dicaments et de rĂ©duire lâĂ©mergence et la diffusion de lâantibiorĂ©sistance. LâHomme et lâanimal partageant le mĂȘme environnement et les mĂȘmes antibiotiques, de fait, leurs santĂ©s constituent donc une seule et mĂȘme santĂ©. Le bon usage des antibiotiques doit s'appliquer au niveau mondial et dans tous les secteurs afin de garantir lâefficacitĂ© durable de ces mĂ©dicaments prĂ©cieux et en nombre limitĂ©
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