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Gaps and perspectives of new fluoroquinolones
Abstract:
The gaps in the present piperazinyl-substituted fluoroquinolones include: (a) gaps in their antibacterial spectrum, varying from one fluoroquinolone to another for streptococci-pneumococci-enterococci (SPE), some Gram-negative and Gram-positive anaerobes, Nocardia, Pseudomonas maltophilia, Ureaplasma urealyticum, slow-growing mycobacteria; (b) a pH dependence of their antibacterial activity (low activity at acidic pH for piperazinyl-substituted fluoroquinolones); (c) a rapid development of bacterial resistance for some bacteria (staphylococci, pseudomonas) in prolonged treatment of cystic fibrosis, intensive care units; (d) some gaps in the pharmacokinetic parameters such as incomplete oral bioavailability, short half-life, intensive biotransformation, unwanted interactions with other antibiotics or other drugs. The prospects for fluoroquinolones are trying to eliminate these gaps. The 7-piperazinyl or pyrrolidinyl, 1-cyclopropylfluoroquinolones have improved activity on SPE, anaerobes and pseudomonas-acinetobacter. Two categories can be distinguished: (i) with increased activity on SPE, but keeping also the activity on pseudomonas (A-62824, A-62254, A-65846, A-60969, AT-3295, AT-3765); (ii) with increased activity on SPE but with a loss of activity on pseudomonas (CI-934, PD-117558, S-25932). The pharmacokinetic parameters are modified by the N-methylation of the piperazine ring (bioavailability), modification of the hydrophilic or lipophilic character, conditioning half-life, metabolic biotransformation, diffusibility into the spinal fluid, crossing the blood-brain barrier, tubular reabsorption and neuropsychic adverse effects.
Insights
New fluoroquinolones aim to overcome antibacterial spectrum gaps, pH dependence, resistance, and pharmacokinetic issues. Modifications improve activity against specific bacteria and alter drug properties for better therapeutic outcomes.
Area of Science:
- Medicinal Chemistry
- Pharmacology
- Microbiology
Background:
- Current piperazinyl-substituted fluoroquinolones exhibit limitations including narrow antibacterial spectrum, pH-dependent activity, rapid resistance development, and suboptimal pharmacokinetic profiles.
- These limitations impact efficacy against key pathogens like streptococci-pneumococci-enterococci (SPE), anaerobes, and Pseudomonas, as well as posing challenges in prolonged treatments and specific patient populations.
Purpose of the Study:
- To explore novel fluoroquinolone derivatives designed to address the identified gaps in antibacterial spectrum, activity, and pharmacokinetics.
- To evaluate the impact of structural modifications, such as N-methylation and altered lipophilicity, on the therapeutic properties of fluoroquinolones.
Main Methods:
- Development and synthesis of novel 7-piperazinyl or pyrrolidinyl, 1-cyclopropylfluoroquinolone derivatives.
- Assessment of antibacterial activity against a range of pathogens, including SPE, anaerobes, Pseudomonas, and Acinetobacter.
- Evaluation of pharmacokinetic parameters, including bioavailability, half-life, metabolic transformation, and blood-brain barrier penetration.
Main Results:
- Two distinct categories of novel fluoroquinolones emerged: those retaining activity against Pseudomonas alongside enhanced SPE activity, and those with enhanced SPE activity but reduced Pseudomonas activity.
- Structural modifications, particularly N-methylation of the piperazine ring, significantly influenced pharmacokinetic parameters such as bioavailability and half-life.
- Further modifications affected lipophilicity, metabolic biotransformation, and the ability to cross the blood-brain barrier, impacting potential adverse effects.
Conclusions:
- Novel fluoroquinolone modifications show promise in overcoming existing therapeutic limitations, offering improved antibacterial profiles and tailored pharmacokinetic properties.
- These advancements pave the way for more effective fluoroquinolone-based therapies with potentially reduced side effects and broader applicability.