Characterization of Polymyxin B Biodistribution and Disposition in an Animal Model

175

120

Nephrotoxicity is a common adverse effect of the clinically used polymyxins, colistin and polymyxin B. This adverse effect is dose limiting for both polymyxins, as the plasma polymyxin concentrations associated with renal damage overlap those required for antibacterial effect. Since development of acute kidney injury (AKI) during therapy is highly undesirable, it is extremely important to know whether there is any difference between the nephrotoxic potential of colistin (administered as its inefficient prodrug, colistimethate) and polymyxin B (administered as the active form). Both polymyxins are cytotoxic to renal tubular cells and are prone to cause nephrotoxicity in vivo because of the renal handling mechanisms that facilitate accumulation of these compounds in these cells, processes that are reviewed in this article. Also reviewed are the emerging data that strongly suggest significantly higher rates of AKI in patients treated with colistimethate compared to patients treated with polymyxin B. This finding may be due to differences in pharmacokinetics and renal handling mechanisms of colistimethate and formed colistin versus polymyxin B, and consequently the relative amount of polymyxin material delivered to tubular cells. A lower risk of AKI with polymyxin B is one of several potential advantages over colistimethate. The relative safety and efficacy of the two agents require closer examination in well-designed clinical studies.

Section: To What Extent Do Polymyxins Accumulate In the Kidney And Whmentioning

confidence: 93%

Section: To What Extent Do Polymyxins Accumulate In the Kidney And Whmentioning

confidence: 99%

Section: To What Extent Do Polymyxins Accumulate In the Kidney And Whmentioning

confidence: 99%

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Nephrotoxicity of Polymyxins: Is There Any Difference between Colistimethate and Polymyxin B?

Zavascki

Nation

2017

175

120

“…Colistin is a polycation with 5 free amino groups that may, in part, be responsible for its ability to bind electrostatically to negatively charged tissue phospholipids (42,43). Animal studies have shown that colistin and polymyxin B accumulate in tissues, including the lungs (44)(45)(46). Unlike colistin, CMS has poor tissue binding properties which may be attributed to the amine side chains protected by sulfomethyl groups (2,43,45).…”

Section: Discussionmentioning

confidence: 99%

Substantial Targeting Advantage Achieved by Pulmonary Administration of Colistin Methanesulfonate in a Large-Animal Model

Landersdorfer

Nguyen

Lieu

et al. 2017

Colistin, administered as its inactive prodrug colistin methanesulfonate (CMS), is often used in multidrug-resistant Gram-negative pulmonary infections. The CMS and colistin pharmacokinetics in plasma and epithelial lining fluid (ELF) following intravenous and pulmonary dosing have not been evaluated in a large-animal model with pulmonary architecture similar to that of humans. Six merino sheep (34 to 43 kg body weight) received an intravenous or pulmonary dose of 4 to 8 mg/kg CMS (sodium) or 2 to 3 mg/kg colistin (sulfate) in a 4-way crossover study. Pulmonary dosing was achieved via jet nebulization through an endotracheal tube cuff. CMS and colistin were quantified in plasma and bronchoalveolar lavage fluid (BALF) samples by high-performance liquid chromatography (HPLC). ELF concentrations were calculated via the urea method. CMS and colistin were comodeled in S-ADAPT. Following intravenous CMS or colistin administration, no concentrations were quantifiable in BALF samples. Elimination clearance was 1.97 liters/h (4% interindividual variability) for CMS (other than conversion to colistin) and 1.08 liters/h (25%) for colistin. On average, 18% of a CMS dose was converted to colistin. Following pulmonary delivery, colistin was not quantifiable in plasma and CMS was detected in only one sheep. Average ELF concentrations (standard deviations [SD]) of formed colistin were 400 (243), 384 (187), and 184 (190) mg/liter at 1, 4, and 24 h after pulmonary CMS administration. The population pharmacokinetic model described well CMS and colistin in plasma and ELF following intravenous and pulmonary administration. Pulmonary dosing provided high ELF and low plasma colistin concentrations, representing a substantial targeting advantage over intravenous administration. Predictions from the pharmacokinetic model indicate that sheep are an advantageous model for translational research.

“…There is evidence suggesting that polymyxin B is not eliminated through the renal route (5,6). However, pharmacokinetic studies have reported preferential accumulation and prolonged residence of polymyxin B in rat kidneys (7,8). Several studies have also reported a daily dose of polymyxin B as an independent risk factor associated with drug nephrotoxicity (9)(10)(11).…”

mentioning

confidence: 99%

Role of Renal Drug Exposure in Polymyxin B-Induced Nephrotoxicity

Manchandani

Zhou

Babic

et al. 2017

Self Cite

Despite dose-limiting nephrotoxic potentials, polymyxin B has reemerged as the last line of therapy against multidrug-resistant Gram-negative bacterial infections. However, the handling of polymyxin B by the kidneys is still not thoroughly understood. The objectives of this study were to evaluate the impact of renal polymyxin B exposure on nephrotoxicity and to explore the role of megalin in renal drug accumulation. Sprague-Dawley rats (225 to 250 g) were divided into three dosing groups, and polymyxin B was administered (5 mg/kg, 10 mg/kg, and 20 mg/kg) subcutaneously once daily. The onset of nephrotoxicity over 7 days and renal drug concentrations 24 h after the first dose were assessed. The effects of sodium maleate (400 mg/kg intraperitoneally) on megalin homeostasis were evaluated by determining the urinary megalin concentration and electron microscopic study of renal tissue. The serum/renal pharmacokinetics of polymyxin B were assessed in megalin-shedding rats. The onset of nephrotoxicity was correlated with the daily dose of polymyxin B. Renal polymyxin B concentrations were found to be 3.6 Ϯ 0.4 g/g, 9.9 Ϯ 1.5 g/g, and 21.7 Ϯ 4.8 g/g in the 5-mg/kg, 10-mg/kg, and 20-mg/kg dosing groups, respectively. In megalin-shedding rats, the serum pharmacokinetics of polymyxin B remained unchanged, but the renal exposure was attenuated by 40% compared to that of control rats. The onset of polymyxin B-induced nephrotoxicity is correlated with the renal drug exposure. In addition, megalin appears to play a pivotal role in the renal accumulation of polymyxin B, which might contribute to nephrotoxicity. KEYWORDS Polymyxin B, renal drug concentration, megalin, polymyxins T here is a renewed interest in the clinical use of polymyxins due to the increased prevalence of infections caused by multidrug-resistant Gram-negative bacteria (1). Many currently available antibiotics are no longer effective against these resistant bacterial strains. Additionally, the situation is further exacerbated by the limited number of new antibacterial agents in the advanced drug development pipeline. Consequently, the polymyxins have emerged as the last treatment resort against these life-threatening infections.Polymyxins (polymyxin B and polymyxin E [colistin]) are cyclic polypeptide antibiotics which were available for clinical use in the 1950s. However, the clinical use of polymyxins was considerably reduced in the early 1970s due to concerns about nephrotoxicity (2-4). Despite being available for decades, the correlation between the pharmacokinetics and toxicodynamic profiles of polymyxin B is still not thoroughly understood. This knowledge gap often hinders the optimal clinical use of polymyxin B. There is evidence suggesting that polymyxin B is not eliminated through the renal route (5, 6). However, pharmacokinetic studies have reported preferential accumulation and prolonged residence of polymyxin B in rat kidneys (7,8). Several studies have also reported a daily dose of polymyxin B as an independent risk factor associated with...