Development and evaluation of an antibiotic pharmaceutical form for inhalation against resistant pulmonary bacteria of Pseudomonas aeruginosa

Plusieurs approches ont été envisagées pour lutter contre la propagation des souches bactériennes résistantes en constante expansion. L’une des plus prometteuses consiste en la combinaison d’antibiotiques avec d’autres entités chimiques non antimicrobiennes « les adjuvants » tels que les dérivés de type polyaminoisoprényle en offrant un meilleur accès interne aux antibiotiques administrés conjointement et/ou en inhibant leur expulsion. L’évaluation in vitro de leurs activités potentialisatrices de l’action de la doxycycline vis-à-vis de la bactérie P. aeruginosa nous a permis d’identifier le meilleur dérivé (le composé NV716). Une solution pour inhalation à base de leur combinaison (NV716/doxycycline) a été développée et évaluée selon les recommandations de la pharmacopée (EP, USP) en utilisant le Next Generation Impactor. Le diamètre aérodynamique des gouttelettes (MMAD = 3,4-4,4 μm) a été démontré conforme aux normes recommandées pour les aérosols thérapeutiques ( 50%) requise pour maintenir leurs concentrations à un niveau supérieur à leurs Concentrations Minimales Inhibitrices au site d'infection. Une étude supplémentaire a ensuite été menée sur l'administration pulmonaire de cette même combinaison (NV716/doxycycline) sous forme d’une poudre, nous avons ainsi pu identifier les facteurs influençant le comportement aérodynamique de notre poudre combinée pour inhalation et la meilleure formulation a été obtenue en regroupant les facteurs optimaux sans utiliser un panel d'excipients qui peuvent affecter négativement les voies respiratoires déjà affaiblies par une infection à P. aeruginosa.Several approaches have been considered to fight the spread of ever-expanding resistant bacterial strains and one of the most promising is the combination of antibiotics with non-antimicrobial chemical entities namely adjuvants such as polyaminoisoprenyl derivatives by offering them a better internal access and/or inhibiting their expulsion. Evaluation of their potentiating activities with respect to the action of doxycycline against P. aeruginosa allowed us to identify the best derivative (compound NV716). An inhalation solution based on the NV716/doxycycline combination was developed and evaluated using a Next Generation Impactor. The aerodynamic droplet diameter (MMAD = 3.4-4.4 μm) meets the recommended standards for therapeutic aerosols ( 50%) required to maintain their concentrations above their Minimum Inhibitory Concentrations (MICs) at the site of infection.An additional study was then performed for pulmonary administration of the same combination as a powder. We were able to identify the factors influencing the aerodynamic behavior of our combination and the best formulation by combining some optimal factors without using a panel of excipients that can negatively affect the airways

Scope and limitations on aerosol drug delivery for the treatment of infectious respiratory diseases

International audienc

Antibiotic Adjuvants: Make Antibiotics Great Again!

International audienceDuring the last decades, multiple approaches have been developed to combat bacterial resistance. However, the combination of antibiotic resistance mechanisms by bacteria and the limited number of effective antibiotics available, decreases the number of the interventions for the treatment of current bacterial infections. The solution to emerging antibiotic resistance will likely involve combination therapies of existing antibiotics and smart adjuvants, which re-empower the antibiotic agent to become efficacious against the resistant strain of interest. In this context, amphiphatic molecules provide the opportunity to target difficult-to-traverse bacterial membranes. We will depict herein that a reasoned adjuvant design permits to perform polypharmacy on bacteria by not only providing greater internal access to the co-dosed antibiotics but also by de-energizing the efflux pumps used by the bacteria to escape antibiotic action

Characterization of a new aerosol antibiotic/adjuvant combination for the treatment of P. aeruginosa lung infections

International audienceThe lack of novel classes of antibiotics as well as the constant increase of multidrug resistant bacteria are leaving the clinicians disarmed to treat bacterial infections, especially those caused by Gram-negative pathogens. Among all the investigated solutions, the design of adjuvants able to enhance antibiotics activities appears to be one of the most promising. In this context, a polyamino-isoprenyl derivative has been recently identified to be able to potentiate, at a very low concentration the activity of doxycycline against P. aeruginosa bacterial strains by increasing its intracellular concentration. On the other hand, since aerosol therapy allows a rapid drug administration and targets the respiratory system by avoiding the first pass effect and minimizing undesirable systemic effects, we have developed the first adjuvant/antibiotic combination in an aerosolized form and demonstrated the feasibility of such an approach. Thus, combination aerosol droplets have been demonstrated in sizes suitable for inhalation (3.4 and 4.4 μm mass median aerodynamic diameter and 54 and 60% of the aerodynamic particle size distribution less than 5 μm, as measured for the adjuvant NV716 and doxycycline, respectively and with properties (stoichiometric 1:1 ratio of NV716 salt to drug) that would support further development as an inhaled dosage form. Taken together, our results suggest that these molecules could be successfully delivered at the requested concentration in the lungs and then able to decrease drug consumption as well as increase treatment efficacy

Feasibility of an inhaled antibiotic/adjuvant dry powder combination using an experimental design approach

International audienc

Antibiotic adjuvants to rescue Pseudomonas aeruginosa from tetracycline antibiotics resistance

International audienceAn attractive antibiotic-adjuvant strategy consisting in the design and synthesis of polyaminoisoprenyl molecules able to restore antibiotic activity of tetracycline antibiotics against resistant Pseudomonas aeruginosa bacterial strains has been developed. These chemosensitizers are readily prepared from geraniol and farnesol in an efficient two steps synthesis with good to moderate yields varying from 38 to 64% and leading to a significant decrease of antibiotic resistance. Thus, the influence of the nature of the tetracycline antibiotic used as well as the structure of the polyaminoisoprenyl derivatives involved on the outcome of the antibiotic-adjuvant combination against P. aeruginosa resistance to tetracyclines were investigated. Additionally, our data suggested that their mechanism of action is closely associated with the increase of the outer-membrane permeability

Spermine Derivatives of Indole‐3‐carboxylic Acid, Indole‐3‐acetic Acid and Indole‐3‐acrylic Acid as Gram‐Negative Antibiotic Adjuvants

International audienceThe discovery of new antibiotic adjuvants is an attractive option for overcoming antimicrobial resistance. We have previously reported the discovery of a bis-6-bromoindolglyoxylamide derivative of spermine as being able to enhance the action of antibiotics against Gram-negative bacteria but suffers from being cytotoxic and red-blood cell haemolytic. A series of analogues was prepared exploring variation of the indolglyoxylamide unit, to include indole-3-acrylic, indole-3-acetic and indole-3-carboxylate units, and evaluated for antibiotic enhancing properties against a range of Gram-negative bacteria, and for intrinsic antimicrobial, cytotoxic and haemolytic properties. Two spermine derivatives, bearing 5-bromo-indole-3-acetic acid (17) and 5-methoxy-indole-3-acrylic acid (14) end groups were found to exhibit good to moderate antibiotic adjuvant activities for doxycycline towards the Gram-negative bacteria Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae, but with more modest intrinsic antimicrobial activity and greatly reduced cytotoxic and haemolytic properties. The mechanism of action of the latter derivative identified its ability to disrupt the outer membranes of bacteria and to inhibit the AcrAB-TolC efflux pump directly or by inhibiting the proton gradient

Valorisation of the diterpene podocarpic acidantibiotic and antibiotic enhancing activities of polyamine conjugates

International audienceAs part of our search for new antimicrobials and antibiotic adjuvants, a series of podocarpic acid-polyamine conjugates have been synthesized. The library of compounds made use of the phenolic and carboxylic acid moieties of the diterpene allowing attachment of polyamines (PA) of different lengths to afford a structurallydiverse set of analogues. Evaluation of the conjugates for intrinsic antimicrobial properties identified two derivatives of interest: a PA3-4-3 (spermine) amide-bonded variant 7a that was a non-cytotoxic, non-hemolytic potent growth inhibitor of Gram-positive Staphylococcus aureus (MRSA) and 9d, a PA3-8-3 carbamate derivative that was a non-toxic selective antifungal towards Cryptococcus neoformans. Of the compound set, only one example exhibited activity towards Gram-negative bacteria. However, in the presence of subtherapeutic amounts of either doxycycline (4.5 µM) or erythromycin (2.7 M) several analogues were observed to exhibit weak to modest antibiotic adjuvant properties against Pseudomonas aeruginosa and/or Escherichia coli. The observation of strong cytotoxicity and/or hemolytic properties for subsets of the library, in particular those analogues bearing methyl ester or n-pentylamide functionality, highlighted the fine balance of structural requirements and lipophilicity for antimicrobial activity as opposed to mammalian cell toxicity

Total synthesis of the four stereoisomers of cyclo(L-Trp-L-Arg) raises uncertainty of the structures of the natural products and invalidates their promising antimicrobial activities

International audienceNew therapeutic options to combat the growing incidence of antimicrobial resistance 16 are urgently needed. A 2015 publication reported the isolation and biological evaluation of two 17 diketopiperazine natural products cyclo(L-Trp-L-Arg) (CDP 2) and cyclo(D-Trp-D-Arg) (CDP 3) 18 from an Achromobacter sp. bacterium, finding that the latter metabolite in particular exhibited 19 strong antibacterial activity towards a range of wound-related microorganisms and could syner-20 gise the action of ampicillin. Intrigued by these biological activities and noting inconsistencies in 21 the structural characterization of the natural products we have synthesized the four diastereomers 22 of cyclo(Trp-Arg) and evaluated them for antimicrobial and antibiotic enhancement properties. 23 Detailed comparison of spectroscopic data raises uncertainty regarding the structure of CDP 2 and 24 disproves the structure of CDP 3. In our hands, none of the four stereoisomers of cyclo(Trp-Arg) 25 exhibited detectable intrinsic antimicrobial properties towards a range of Gram-positive and 26 Gram-negative bacteria or fungi nor could they potentiate the action of antibiotics. These discrep-27 ancies in biological properties, compared to the activities reported in the literature, reveal that 28 these specific cyclic dipeptides do not represent viable templates for the development of new 29 treatments for microbial infections

Synthesis, docking and evaluation of in vitro anti-inflammatory activity of novel morpholine capped β-lactam derivatives

This study reports the synthesis and biological investigation of three series of novel monocyclic β-lactam derivatives bearing a morpholine ring substituent on the nitrogen. The resulting β-lactam adducts were synthesized via Staudinger's [2+2]-ketene-imine cycloaddition reaction. New synthesized products were fully characterized by spectral data and elemental analyses, and then evaluated for anti-inflammatory activity toward human inducible nitric oxide synthase (iNOS) and cytotoxicity toward HepG2 cell line. The compounds 3e, 3h, 3k, 5c, 5f, 6c, 6d and 6f showed higher activity with anti-inflammatory ratio values of 38, 62, 51, 72, 51, 35, 55 and 99, respectively, in comparison to the reference compound dexamethasone having an antiinflammatory ratio value of 32. Hence, these compounds can be considered as potent iNOS inhibitors. They also exhibited IC50 values of 0.48 + 0.04 mM, 0.51 + 0.01 mM, 0.22 + 0.02 mM, 2 0.12 + 0.00 mM, 0.25 + 0.05 mM, 0.82 + 0.07 mM, 0.44 + 0.04 mM and 0.60 + 0.04 mM, respectively, in comparison with doxorubicin (IC50 < 0.01 mM) against HepG2 cells, biocompatibility and nontoxic behavior. In silico prediction of drug-likeness characteristic indicated that the compounds are compliant with the Lipinski and Veber rules. Molecular docking experiments showed a good correlation between the experimental activity and the calculated binding affinity to human inducible nitric oxide synthase, the enzymatic target for the antiinflammatory respons