Antibacterial

In human peripheral blood mononuclear cells (PBMC), polymyxin B (10 μg/mL, 6 hours) decreases the production of TNF-α and IL-10 [3]. MICs of 0.5 mg/l for E. Coli strain IH3080 are demonstrated by Polymyxin B Sulfate's antibacterial properties.

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Polymyxin B, a cyclic peptide antibiotic, is considered to be a rather selective antagonist of protein kinase C. This drug is therefore widely used to evaluate the involvement of protein kinase C in cellular processes. In the present study, we investigated the effects of polymyxin B on the activity of calmodulin-dependent cyclic 3':5'-nucleotide phosphodiesterase in vitro. The drug potently inhibited this enzyme (IC50 80 nM in the presence of 500 microM Ca2+), while about 200-fold higher concentrations were required to inhibit protein kinase C to the same extent. Phosphodiesterase inhibition was competitive with respect to Ca2+ and calmodulin. Evidence for the formation of a complex between polymyxin B and calmodulin was obtained by polyacrylamide gel electrophoresis under non-denaturing conditions, and by affinity chromatography of calmodulin on polymyxin B-agarose. We therefore suggest that, at least in vitro, polymyxin B is a potent and selective inhibitor of calmodulin. [8]

At 20 mg/kg and 5 mg/kg No, Polymyxin B (5–20 mg/kg, IV; once daily for 7 days) reached nephrotoxicity endpoints in the Sprague-Dawley rat model[2].

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A mouse model of lung or thigh infection demonstrates antibacterial activity when treated with Polymyxin B Sulfate (0.5-120 mg/kg; s.c.).
The mouse bactericidal effect of Polymyxin B Sulfate (2 mg/kg, s.c.) against E. coli strain IH3080 is strong.

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The pharmacokinetics of polymyxin B were well described by a model comprising parallel linear and saturable pathways for absorption and elimination. Plasma binding of polymyxin B was constant (P > 0.05) over the range ∼0.9-37 mg/L; average (±SD) percentage bound was 91.4 ± 1.65. In thigh infection, antibacterial effect was well correlated with fAUC/MIC (R2 = 0.89). Target values of fAUC/MIC for stasis and 1 log10 kill were 1.22-13.5 and 3.72-28.0, respectively; 2 log10 kill was not achieved for any strain, even at the highest tolerated dose. There was no difference (P > 0.05) in antibacterial activity between polymyxin B and colistin with equimolar doses. It was not possible to achieve stasis in lung infection, even at the highest dose tolerated by mice. [5]

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Polymyxin B, a relatively toxic antibiotic, has potent endotoxin-neutralizing properties that may be beneficial as adjunctive therapy in gram-negative sepsis. Polymyxin B nonapeptide (deacylated polymyxin B) is devoid of antibiotic activity but retains the capacity to disorganize the outer membrane of gram-negative bacteria. To evaluate the potential therapeutic usefulness of this derivative, we produced purified polymyxin B nonapeptide, tested its in vivo toxicity in animals, and evaluated its in vitro antiendotoxin activity. Effectiveness as an antiendotoxin agent was assessed by examining the ability of polymyxin B nonapeptide to block the enhanced release of toxic oxygen radicals induced by lipopolysaccharide in human neutrophils (priming). In vivo, at doses of 1.5 and 3.0 mg/kg, polymyxin B nonapeptide did not exhibit the neuromuscular blocking, neurotoxic, or nephrotoxic effects that were observed with polymyxin B sulfate. Both polymyxin B and polymyxin B nonapeptide inhibited lipopolysaccharide-induced neutrophil priming in a concentration-dependent manner, but the parent compound, polymyxin B, was 63 times more effective on a weight basis. The inhibitory activity of both compounds, however, diminished rapidly when they were added after the start of the lipopolysaccharide-neutrophil incubation. We conclude that polymyxin B nonapeptide is less toxic than polymyxin B and, at the doses tested, lacks the neurotoxicity and nephrotoxicity of the parent compound. Polymyxin B nonapeptide retains the antiendotoxin activity of polymyxin B but is much less potent. The findings suggest that these compounds block an early step in the neutrophil priming process, possibly lipopolysaccharide attachment to or insertion into the neutrophil membrane.[4]

Bacterial strain and the inoculum [8]
The smooth, encapsulated E. coli strain IH3080 (O18:K1:H7) is a clinical isolate from the CSF of a human neonate with meningitis.10 The MICs of polymyxin B, NAB739 and NAB7061 for this strain, as determined by the agar dilution method using Mueller–Hinton agar according to the CLSI,14 are 0.5 mg/L, 1 mg/L and >32 mg/L, respectively.7 Bacterial suspensions for inoculation of mice were prepared at room temperature from fresh overnight cultures on 5% blood agar plates produced by the Statens Serum Institut. The inoculum was prepared by picking up colonies and suspending them in sterile 0.9% saline to an optical density of 0.12 at 540 nm, giving a density of 108 cfu/mL. Dilutions of this suspension were made in 0.9% saline. If not otherwise indicated, the suspension with 106 cfu/mL was used in the challenge studies. Preparation of the inoculum and inoculation were performed within 1 h. For each experiment, the size of the inoculum was determined by making 10-fold dilutions of the suspension used for the inoculum in 0.9% saline, of which 20 µL was plated on 5% blood agar plates with subsequent counting of colonies after incubation overnight at 35°C in ambient air.

Cell culture and cytokine measurement [3]
Human peripheral blood mononuclear cells (PBMC) were used to test the ability of PMB to neutralize the effect of LPS itself and as contaminant of three different S. mansoni recombinant proteins produced in E. coli in inducing cytokine production. PBMC were obtained through the Ficoll-Hypaque gradient and adjusted to a concentration of 3 × 106 cells/ml in RPMI 1640 containing 10% of normal human serum (AB+, heat-inactivated), 100 U/mL penicillin, 100 μg/mL streptomycin, 2 mM L-glutamine, 30 mM HEPES. Cells were cultured in vitro in the presence or absence of polymyxin B (10 μg/mL) and were stimulated with LPS (0.14 ng/mL, which is the mean of contaminant concentration in the cultures stimulated with S. mansoni antigens), S. mansoni recombinant protein rP24, rSm14, rSm22.6 (10 μg/mL) and with the mitogen phytohemaglutinin (PHA) (2 μg/mL). Unstimulated cells were also cultured as a control. Cultures were incubated at 37°C, 5% CO2 for 6, 12, 24 and 48 hours. After incubation, the supernatants were collected and maintained at -20°C, for later measurement of cytokines. Levels of TNF-α and IL-10 in culture supernatants were determined by ELISA sandwich technique, using commercially available kits, and the results were expressed in picograms per milliliter based on a standard curve.

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Addition of polymyxin B to the cultures [3]
Suspension of peripheral blood mononuclear cells (3 × 106 cells/mL) were pre-incubated with Polymyxin B in the concentration of 10 and 20 μg/mL for 30 minutes at 37°C, 5% CO2. They were then incubated with the different recombinant proteins (10 μg/mL) or LPS (0.14 ng/mL) and the cultures were incubated for 6 to 48 hours as described above. Polymyxin B (10 or 20 μg/mL) was also added each 12 hours, during all culture period.

Animal Model: Eight-week-old, 24-30 g, female Swiss mice[5]
\nDosage: For the model of thigh infection, 0.5-120 mg/kg; for the lung infection mode, 5-120 mg/kg
\nAdministration: S.c.
\nResult: demonstrated antibacterial activity against three strains of K. pneumoniae.\n

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\nPharmacokinetics of polymyxin B in neutropenic infected mice [5]
\nThe PK of polymyxin B was determined following single-dose administration of 2, 4, 8, 16 and 32 mg/kg of polymyxin B to neutropenic thigh-infected mice. Plasma samples were collected from three or four mice at each of multiple times up to 12 h following administration; the sampling schedule varied somewhat across the five doses to maximize the yield of information. The protein binding of polymyxin B in pooled plasma collected from infected neutropenic mice was determined by ultracentrifugation using previously described conditions and procedures to minimize adsorption of polymyxin B in protein-free supernatant samples.5 Binding was determined in drug-free plasma that had been spiked to achieve 10 polymyxin B concentrations across the range ∼0.9–37 mg/L, encompassing the relevant range of total plasma concentrations in the single-dose PK studies (described above) and the dose fractionation PK/PD studies (described below). Concentrations of polymyxin B in samples of supernatant obtained by ultracentrifugation and whole plasma were quantified as before.5,11\n

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\nPharmacokinetics/pharmacodynamics of polymyxin B in thigh and lung infection models [5]
\nTreatment with subcutaneously administered polymyxin B sulphate (daily dose range 0.5–120 mg/kg in the thigh infection model and 5–120 mg/kg in the lung infection model) commenced 2 h following inoculation. The maximum dose tolerated by mice was 120 mg/kg per day. The following dose-fractionated regimens were used against strain FADDI-KP032 in the thigh infection model: once-daily administration of 0.5, 10, 20, 30 and 45 mg/kg; 12 hourly administration of 5, 10, 15, 22.5, 30 and 45 mg/kg; 8 hourly administration of 0.83, 1.67, 5, 3.33, 6.67, 7.5, 10, 15, 20, 25, 30 and 40 mg/kg; and 4 hourly administration of 1.67, 3.33, 5, 7.5, 10, and 15 mg/kg. In the remaining PK/PD studies the daily doses were divided equally and administered at 8 hourly intervals. Bacterial burdens in lungs or thighs (dependent on the model) were determined at 2 h after inoculation (untreated controls) and 24 h later (untreated controls and polymyxin B-treated mice), as described previously.5\n
\nFor strains FADDI-KP032 and ATCC BAA-2146, the antibacterial effects of polymyxin B and colistin were compared in the thigh infection model. For FADDI-KP032, equimolar daily doses of each polymyxin were studied at four dose levels (polymyxin B sulphate at 22.5, 45, 90 and 120 mg/kg/24 h, corresponding to colistin sulphate at 21.9, 43.9, 87.7 and 117.1 mg/kg/24 h; n = 4 for each treatment). For ATCC BAA-2146, the comparison was conducted with the first three equimolar dose levels. For each polymyxin, the daily dose was divided equally and administered 8 hourly.\n

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\nDose-fractionation studies with subcutaneous polymyxin B were conducted in neutropenic mice in which infection with three strains of K. pneumoniae had been produced in thighs or lungs. Dosing (thigh infection 0.5-120 mg/kg/day; lung infection 5-120 mg/kg/day) commenced 2 h after inoculation, and bacterial burden was measured 24 h later. Plasma exposure measures for unbound polymyxin B were from population pharmacokinetic analysis of single doses and plasma protein binding by ultracentrifugation. The inhibitory sigmoid dose-effect model was employed to determine the relationship between exposure and efficacy. Antibacterial activities of polymyxin B and colistin against thigh infection were compared at equimolar doses generating exposures resulting in maximal antibacterial activity. [5]\n

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\nMouse peritonitis model [7]
\nInoculation was performed by intraperitoneal injection of 0.5 mL of the E. coli suspension. After the inoculation, the mice were observed for 5 h for clinical signs of infection such as lack of curiosity, social withdrawal, changes in body position and pattern of movement, distress and pain. Cfu values in the peritoneum were determined at 1, 4 and 7 h post-inoculation, if not otherwise indicated. After the mice had been sacrificed by cervical dislocation, peritoneal washes were performed by injecting 2 mL of sterile saline intraperitoneally, followed by gentle massage of the abdomen and opening the peritoneum to collect fluid. Peritoneal fluids were serially diluted (10-fold dilutions) and 20 µL was plated on selective blue agar plates produced at the Statens Serum Institut with subsequent counting of colonies after incubation overnight at 35°C in ambient air. No antibiotic carry-over effect in terms of growth inhibition was observed in the spot 10-fold denser than the spot that was counted. All cfu values are averages (of raw cfu values) ±SD from determinations performed from three or four animals.\n
\nNAB737 and NAB739 (1, 2 and 4 mg/kg body weight) and polymyxin B (2 mg/kg) were administered at 1 and 3 h post-inoculation as subcutaneous injections in the neck region in a volume of 0.2 mL per dose. Control mice received saline.\n
\nNAB7061 (5 mg/kg subcutaneously) and erythromycin (10 mg/kg subcutaneously) were administered at 1 h post-inoculation and a second dose of NAB7061 (5 mg/kg subcutaneously) was given at 3 h post-inoculation. Controls included treatment with either drug alone, as well as treatment with saline only.

Metabolism / Metabolites
Elimination Pathway: This drug is primarily excreted slowly via the kidneys. Currently, there is limited information regarding the pharmacokinetics of polymyxin B in mice. He et al. reported data from a study using a single intravenous injection of 3 mg/kg; Bowers et al. used a single intraperitoneal injection of 10 mg/kg; plasma samples were collected at 6 and 4 hours, respectively. To minimize the number of animals, we selected mice with thigh infection for our study and assumed that there was no difference in the pharmacokinetics of polymyxin B between thigh and lung infection mice. Previous studies have shown that the pharmacokinetics of ceftazidime and avibactam are not different between the two infection sites in mice with thigh and lung infection. In this study, the total plasma concentration-time curves of polymyxin B in a single-dose pharmacokinetic study of neutropenia-infected mice are shown in Figure 1, and the estimated pharmacokinetic parameters of the population pharmacokinetic model are shown in Table 1. Careful analysis of the curves revealed that the pharmacokinetics of polymyxin B exhibited a certain degree of nonlinearity within the dose range of 2–32 mg/kg subcutaneously injected. Similar nonlinearity was observed in mice infected with neutropenia after a single subcutaneous injection of polymyxin B within a narrow dose range (10–40 mg/kg). In this study, we explored various methods to address nonlinearity issues in the population pharmacokinetics analysis of polymyxin B. Ultimately, we selected the optimal model, which incorporates both parallel linear pathways and saturation pathways for absorption and elimination at the subcutaneous injection site (Figure 2). All parameters in the final model were used to describe the pharmacokinetic curves. Visual prediction tests showed that the model had excellent predictive performance within the studied dose range (Figure 3) [5]. In the plasma of neutropenic infected mice, the protein binding rate of polymyxin B was concentration-independent within the concentration range of approximately 0.9–37 mg/L (P > 0.05). At 10 concentration points within this range, the mean (±SD) binding percentage of polymyxin B was 91.4 ± 1.65%. Therefore, the mean free fraction of polymyxin B in plasma was 0.086, which was used to determine the fAUC/MIC, fCmax/MIC, and fT>MIC values for each dosing regimen in the PK/PD study. The free fraction of polymyxin B in the plasma of neutropenic infected mice (0.086) was almost identical to the previously reported free fraction of colistin (0.084). Clearly, the free concentrations of polymyxin B, colistin, and some of their analogues in mouse plasma are significantly lower than in human plasma. This is likely due to qualitative or quantitative differences in the plasma proteins involved in polymyxin binding between different species, or differences in the concentrations of endogenous compounds affecting binding. When applying pharmacokinetic/pharmacodynamic data to clinical practice, it must be recognized that the free concentrations of polymyxin B and colistin in the plasma of infected mice with neutropenia are significantly lower than the corresponding values in the plasma of critically ill patients. [5] In the thigh infection model, the bacterial loads of ATCC BAA-2146, FADDI-KP032 and FADDI-KP042 strains at the start of polymyxin B treatment were 6.30 ± 0.67 (n = 8), 6.81 ± 0.13 (n = 12) and 6.92 ± 0.13 (n = 8) log10 cfu/thigh, respectively. Figure 4(a) shows the relationship between the antimicrobial effect of polymyxin B and fAUC/MIC in the dose-fractionation study of FADDI-KP032 in the thigh infection model. The R² value of the inhibitory S-type dose-response model fitting the fAUC/MIC index was 0.89, slightly higher than the corresponding value of fCmax/MIC (R² = 0.88), and significantly higher than the corresponding value of fT>MIC (R² = 0.50); data for the latter two indices are shown in Figure S1 (available in the supplementary data in JAC Online). This is consistent with the results of studies on colistin and polymyxin B against Pseudomonas aeruginosa and Acinetobacter baumannii, which indicate that fAUC/MIC is the optimal PK/PD index for describing the antibacterial activity of polymyxins, although in some reports, fCmax/MIC is only slightly inferior to fAUC/MIC, as shown in this study. The daily dose of polymyxin B required to produce an fAUC/MIC value at the upper limit of the exposure-response curve (Figure 4a) is the maximum tolerable dose in mice. In a mouse thigh infection model, the PK/PD model parameter estimation accuracy of the fAUC/MIC index of polymyxin B against three strains of Klebsiella pneumoniae was high (Table 2). The fAUC/MIC values required to achieve 50% of the maximum drug effect (Emax) were similar to those of colistin against Pseudomonas aeruginosa and Acinetobacter baumannii in a mouse thigh infection model. However, it is noteworthy that the Emax of polymyxin B (2.13–2.90 log10 cfu/thigh) was significantly lower than that of colistin against three Pseudomonas aeruginosa strains (4.97–6.84 log10 cfu/thigh) and three Acinetobacter baumannii strains (3.78–4.61 log10 cfu/thigh) in the same model. Due to the smaller Emax of polymyxin B in this study, the target fAUC/MIC value for 2 log10 bactericidal activity could not be determined (Table 2); the antibacterial and 1 log10 bactericidal target values of polymyxin B against Klebsiella pneumoniae were essentially consistent with the corresponding target values of colistin against Pseudomonas aeruginosa and Acinetobacter baumannii in a mouse thigh infection model. For the three Klebsiella pneumoniae strains, polymyxin B has a relatively wide range of antibacterial and bactericidal target values per log10 (Table 2). Similar or greater inter-strain differences have also been observed in mouse infection studies when other bacteria were treated with non-polymyxin antibiotics. As more information becomes available about the pharmacokinetics of polymyxin B in clinical populations and the relationship between its plasma exposure and patient nephrotoxicity, the pharmacokinetic/pharmacodynamic target values reported in Table 2, as well as future results from studies on other strains, can be used to help develop optimized dosing regimens, as has been the case with colistin. [5]

Toxicity Summary
Polymyxin B sulfate is bactericidal against almost all Gram-negative bacilli except for Proteus spp. Polymyxin B sulfate interacts with the lipopolysaccharide of the outer cytoplasmic membrane of Gram-negative bacteria, altering membrane permeability and leading to cell death. It does not need to enter the cell to exert its effect. Effects During Pregnancy and Lactation ◉ Overview of Use During Lactation Due to poor absorption after topical application, polymyxin B poses a low risk to breastfed infants. Only water-soluble creams or gels should be applied to the breasts, as ointments may expose the infant to high concentrations of mineral oil through licking. ◉ Effects on Breastfed Infants As of the revision date, no relevant published information was found. ◉ Effects on Lactation and Breast Milk As of the revision date, no relevant published information was found.

[1]. Endotoxin removal: how far from the evidence? The EUPHAS 2 Project. Contrib Nephrol. 2010;167:119-125.

[2]. Role of Renal Drug Exposure in Polymyxin B-Induced Nephrotoxicity. Antimicrob Agents Chemother. 2017 Mar 24;61(4):e02391-16.

[3]. Polymyxin B as inhibitor of LPS contamination of Schistosoma mansoni recombinant proteins in human cytokine analysis. Microb Cell Fact. 2007 Jan 3;6:1.

[4]. Purification, toxicity, and antiendotoxin activity of polymyxin B nonapeptide. Antimicrob Agents Chemother. 1989 Sep;33(9):1428-34.

[5]. Pharmacokinetics/pharmacodynamics of systemically administered polymyxin B against Klebsiella pneumoniae in mouse thigh and lung infection models. J Antimicrob Chemother. 2018 Feb 1;73(2):462-468.

[6]. Novel polymyxin derivatives are effective in treating experimental Escherichia coli peritoneal infection in mice. J Antimicrob Chemother. 2010 May;65(5):981-5.

[7].Antagonism of endotoxic glucose dyshomeostasis by protein kinase C inhibitors. Am J Physiol.1991 Jul;261(1 Pt 2):R26-31.

[8]. Polymyxin B is a selective and potent antagonist of calmodulinEur J Pharmacol.1991 May 25;207(1):17-22.

Polymyxin B has been reported to exist in Paenibacillus polymyxa, and relevant data are available. Polymyxin B sulfate is a mixture of polymyxins B1 and B2, extracted from Paenibacillus polymyxa strains. They are basic polypeptides composed of approximately eight amino acids and have cationic detergent effects on cell membranes. Polymyxin B is used to treat Gram-negative bacterial infections but may have neurotoxicity and nephrotoxicity. All Gram-positive bacteria, fungi, and Gram-negative cocci, such as Neisseria gonorrhoeae and Neisseria meningitidis, are resistant to it. It is indicated for the treatment of urinary tract, meningeal, and bloodstream infections caused by susceptible strains of Pseudomonas aeruginosa. Polymyxin B sulfate is a mixture of polymyxins B1 and B2, extracted from Paenibacillus polymyxa strains. These are basic polypeptides composed of approximately eight amino acids, acting as cationic detergents against cell membranes. Polymyxin B is used to treat Gram-negative bacterial infections but may have neurotoxicity and nephrotoxicity. Polymyxin B sulfate is a cyclic peptide. It is a mixture of polymyxins B1 and B2 extracted from Bacillus polymyxa strain A. These are basic polypeptides composed of approximately eight amino acids, acting as cationic detergents against cell membranes. Polymyxin B is used to treat Gram-negative bacterial infections but may have neurotoxicity and nephrotoxicity. See also: Polymyxin B sulfate (note moved to). In summary, to our knowledge, this is the first report of the pharmacokinetic/pharmacodynamic (PK/PD) study of polymyxin B or colistin against Klebsiella pneumoniae in a dynamic infection model. This study demonstrates that fAUC/MIC is the PK/PD index with the highest correlation to bacterial kill rate in a mouse thigh infection model with neutropenia. For the target values of inhibiting colony formation and achieving 1 log10 bactericidal effect, the fAUC/MIC values were in the same range as the target values of colistin for bactericidal effect against Pseudomonas aeruginosa and Acinetobacter baumannii reported in the same dynamic infection model. However, in the comparative part of this study, the maximum bactericidal effect of polymyxin B and colistin against Klebsiella pneumoniae was significantly reduced, indicating that there is a difference in the responsiveness of this pathogen to polymyxin. The efficacy of systemic polymyxin B in treating lung infections of Pseudomonas aeruginosa and Acinetobacter baumannii was worse than that in mice with lung infections of Klebsiella pneumoniae treated with systemic colistin. With a deeper understanding of the population pharmacokinetics of polymyxin B and its relationship with the risk of nephrotoxicity in critically ill patients, the results of this study will help to design optimized polymyxin B administration strategies. [5]

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Objective: Novel synthetic polymyxin derivatives, including NAB737 and NAB739, have comparable antimicrobial activity against common opportunistic pathogen Escherichia coli in vitro to polymyxin B. Another derivative, NAB7061, while lacking direct antibacterial activity, enhances the sensitivity of E. coli to various other antibacterial drugs, including macrolides. The metabolism of NAB739 and NAB7061 in rat kidneys differs from that of polymyxin B. Furthermore, NAB739 and NAB7061 exhibit significantly lower affinity for isolated rat kidney brush border membranes than polymyxin B. This study aimed to investigate the in vivo antibacterial activity of these compounds. Methods: The antibacterial activity of polymyxin derivatives was evaluated using a mouse model of experimental peritonitis. Immunologically normal mice were intraperitoneally injected with E. coli IH3080 and then subcutaneously injected with NAB737, NAB739, or NAB7061, respectively. Results: Compared with the saline control group, after 6 hours of treatment with 1 mg/kg NAB739 (twice) or 4 mg/kg NAB737 (twice), the bacterial load decreased by more than 4.0 log(10). Treatment with NAB7061 (5 mg/kg) in combination with erythromycin (10 mg/kg) twice resulted in a reduction of bacterial load by more than 2.0 log(10) compared to the saline control group within the same time period. Neither NAB7061 nor erythromycin monotherapy was effective. In addition to reducing bacterial load, NAB compounds also improved the clinical condition of mice. Conclusion: We found that three novel synthetic polymyxin B derivatives have a strong in vivo bactericidal effect against Escherichia coli. [8]

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Bacterial lipopolysaccharide-activated protein kinase C (PKC) has recently been considered to be related to the pathogenesis of Gram-negative bacterial sepsis, endotoxemia, hyperinsulinemia, and ultimately glucose homeostasis imbalance. In this study, the peptide antibiotic polymyxin B (PMX-B) and the isoquinoline sulfonamide antibiotic H-7 were used as inhibitors of protein kinase C (PKC) activation to evaluate the responses of control and endotoxin groups of rats to insulin and glucose tolerance tests. Male rats were treated with Salmonella enterica endotoxin (ETX; 0.33 mg/kg intravenously) or saline 120 minutes before either the intravenous insulin tolerance test (IVITT) (human insulin, 1 U/kg) or the intravenous glucose tolerance test (IVGTT) (D-glucose, 1.2 g/kg). Five minutes before the tolerance test, rats were administered H-7 (25 mg/kg) dissolved in dimethyl sulfoxide, PMX-B (0.25 mg/kg) dissolved in saline, or their respective solvents. Neither H-7 nor PMX-B had a significant acute effect on basal plasma glucose or lactate levels. The decrease in plasma concentration during the IVGTT was exacerbated by ETX; however, concomitant administration of H-7 or PMX-B alleviated insulin-induced hypoglycemia. ETX shortened the half-life of glucose during the IVGTT; however, concomitant administration of H-7 or PMX-B reduced the tolerance alteration. In addition, both H-7 and PMX-B can alleviate the insulin elevation induced by IVGTT. Therefore, hyperinsulinemia and glycemic dysregulation in endotoxemia may be mediated by protein kinase C (PKC) activation and can be improved by PKC inhibition. [7]

C56H98N16O13

1203.47672

1188.734

1404-26-8

1405-20-5 (sulfate); 1404-26-8

4868

White to light yellow solid powder

1.3±0.1 g/cm3

1572.3±65.0 °C at 760 mmHg

904.7±34.3 °C

0.0±0.3 mmHg at 25°C

1.593

-3.4

18

18

29

85

2150

0

WQVJHHACXVLGBL-UHFFFAOYSA-N

InChI=1S/C56H98N16O13/c1-7-32(4)13-11-12-16-44(75)63-36(17-23-57)51(80)72-46(34(6)74)56(85)68-39(20-26-60)48(77)67-41-22-28-62-55(84)45(33(5)73)71-52(81)40(21-27-61)65-47(76)37(18-24-58)66-53(82)42(29-31(2)3)69-54(83)43(30-35-14-9-8-10-15-35)70-49(78)38(19-25-59)64-50(41)79/h8-10,14-15,31-34,36-43,45-46,73-74H,7,11-13,16-30,57-61H2,1-6H3,(H,62,84)(H,63,75)(H,64,79)(H,65,76)(H,66,82)(H,67,77)(H,68,85)(H,69,83)(H,70,78)(H,71,81)(H,72,80)

N-[4-amino-1-[[1-[[4-amino-1-oxo-1-[[6,9,18-tris(2-aminoethyl)-15-benzyl-3-(1-hydroxyethyl)-12-(2-methylpropyl)-2,5,8,11,14,17,20-heptaoxo-1,4,7,10,13,16,19-heptazacyclotricos-21-yl]amino]butan-2-yl]amino]-3-hydroxy-1-oxobutan-2-yl]amino]-1-oxobutan-2-yl]-6-methyloctanamide

N-[(2S)-4-amino-1-[[(2S,3R)-1-[[(2S)-4-amino-1-oxo-1-[[(3S,6S,9S,12S,15R,18R,21S)-6,9,18-tris(2-aminoethyl)-15-benzyl-3-[(1R)-1-hydroxyethyl]-12-(2-methylpropyl)-2,5,8,11,14,17,20-heptaoxo-1,4,7,10,13,16,19-heptazacyclotricos-21-yl]amino]butan-2-yl]amino]-3-hydroxy-1-oxobutan-2-yl]amino]-1-oxobutan-2-yl]-6-methyloctanamide; 1404-26-8; POLUMYXIN B; WQVJHHACXVLGBL-BPJDFBQWSA-N;

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O : ~33.33 mg/mL

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)