polymyxiner

Polymyxiner is not a widely recognized compound in standard pharmacology references. The name may be a misspelling or a fictional term. If the reference is to polymyxins, the well-established class of antibiotics, the following overview provides general context.

Polymyxins are a group of cyclic lipopeptide antibiotics produced by Paenibacillus polymyxa. The main clinically used members are polymyxin B and polymyxin E, also known as colistin. They are cationic amphipathic molecules with a fatty acyl tail, which contributes to their interaction with bacterial membranes.

Mechanism of action and spectrum: Polymyxins target the outer membrane of Gram-negative bacteria by binding to lipopolysaccharide and phospholipids, disrupting membrane integrity and increasing permeability. This leads to leakage of cellular contents and cell death. They have strong activity against many Gram-negative pathogens, including Pseudomonas aeruginosa, Acinetobacter species, and resistant Enterobacteriaceae. Activity against Gram-positive bacteria and most anaerobes is limited.

Clinical use and safety: Polymyxins are often used when infections are caused by multidrug-resistant Gram-negative bacteria. Polymyxin B is typically given as an intravenous or intrathecal preparation, while colistin is administered as the prodrug colistin methanesulfonate (CMS) in many regimens. Systemic use is limited by dose-dependent nephrotoxicity and neurotoxicity, requiring careful dosing, monitoring, and renal function assessment. They are also used topically for certain infections and in combination therapies to enhance efficacy.

Resistance and research: Resistance can arise through modifications of lipopolysaccharide that reduce drug binding. This has driven ongoing research into less toxic derivatives, alternative delivery methods, and combination therapies to preserve efficacy while minimizing toxicity.