Population Pharmacokinetics of Polymyxin B and Dosage Optimization in Renal Transplant Patients

Three methods to optimise polymyxin B dosing using estimated AUC after first dose: validation with the data generated by Monte Carlo simulation

To achieve the AUC-guided dosing, we proposed three methods to estimate polymyxin B AUC across 24 h at steady state (AUCSS,24h) using limited concentrations after its first dose.Monte Carlo simulation based on a well-established population PK model was performed to generate the PK profiles of 1000 patients with normal or abnormal renal function. Polymyxin B AUCSS,24h was estimated for each subject using three methods (two-point PK approach, three-point PK approach, and four-point PK approach) based on limited concentration data in its first dose and compared with the actual AUC at steady state calculated using the linear-trapezoidal formula.In patients with normal renal function, the mean bias of two-point PK approach, three-point PK approach, and four-point PK approach was -8.73%, 1.37%, and -0.48%, respectively. The corresponding value was -11.15%, 1.99%, and -0.28% in patients with renal impairment, respectively. The largest mean bias of two-point PK approach, three-point PK approach, and four-point PK approach was -12.63%, -6.47%, and -0.54% when the sampling time shifted.The Excel calculators designed based on the three methods can be potentially used to optimise the dosing regimen of polymyxin B in the clinic.

Pharmacokinetics of polymyxin B in different populations: a systematic review

BACKGROUND AND OBJECTIVES

Despite being clinically utilized for the treatment of infections, the limited therapeutic range of polymyxin B (PMB), along with considerable interpatient variability in its pharmacokinetics and frequent occurrence of acute kidney injury, has significantly hindered its widespread utilization. Recent research on the population pharmacokinetics of PMB has provided valuable insights. This study aims to review relevant literature to establish a theoretical foundation for individualized clinical management.

METHODS

Follow PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, Pop-PK studies of PMB were searched in PubMed and EMBASE database systems from the inception of the database until March 2023.

RESULT

To date, a total of 22 population-based studies have been conducted, encompassing 756 subjects across six different countries. The recruited population in these studies consisted of critically infected individuals with multidrug-resistant bacteria, patients with varying renal functions, those with cystic fibrosis, kidney or lung transplant recipients, patients undergoing extracorporeal membrane oxygenation (ECMO) or continuous renal replacement therapy (CRRT), as well as individuals with obesity or pediatric populations. Among these studies, seven employed a one-compartmental model, with the range of typical clearance (CL) and volume (Vc) being 1.18-2.5L /h and 12.09-47.2 L, respectively. Fifteen studies employed a two-compartmental model, with the ranges of the clearance (CL) and volume of the central compartment (Vc), the volume of the peripheral compartment (Vp), and the intercompartment clearance (Q) were 1.27-8.65 L/h, 5.47-38.6 L, 4.52-174.69 L, and 1.34-24.3 L/h, respectively. Primary covariates identified in these studies included creatinine clearance and body weight, while other covariates considered were CRRT, albumin, age, and SOFA scores. Internal evaluation was conducted in 19 studies, with only one study being externally validated using an independent external dataset.

CONCLUSION

We conclude that small sample sizes, lack of multicentre collaboration, and patient homogeneity are the primary reasons for the discrepancies in the results of the current studies. In addition, most of the studies limited in the internal evaluation, which confined the implementation of model-informed precision dosing strategies.

A systematic evaluation of population pharmacokinetic models for polymyxin B in patients with liver and/or kidney dysfunction

Polymyxin B (PMB) is considered a last-line treatment for multidrug-resistant (MDR) gram-negative bacterial infections. Model-informed precision dosing with population pharmacokinetics (PopPK) models could help to individualize PMB dosing regimens and improve therapy. However, the external prediction ability of the established PopPK models has not been fully elaborated. This study aimed to systemically evaluate eleven PMB PopPK models from ten published literature based on a new independent population, which was divided into four different populations, patients with liver dysfunction, kidney dysfunction, liver and kidney dysfunction, and normal liver and kidney function. The whole data set consisted of 146 patients with 391 PMB concentrations. The prediction- and simulation-based diagnostics and Bayesian forecasting were conducted to evaluate model predictability. In the overall evaluation process, none of the models exhibited satisfactory predictive ability in both prediction- and simulation-based diagnostic simultaneously. However, the evaluation of the models in the subgroup of patients with normal liver and kidney function revealed improved predictive performance compared to those with liver and/or kidney dysfunction. Bayesian forecasting demonstrated enhanced predictability with the incorporation of two to three prior observations. The external evaluation highlighted a lack of consistency between the prediction results of published models and the external validation dataset. Nonetheless, Bayesian forecasting holds promise in improving the predictive performance of the models, and feedback from therapeutic drug monitoring is crucial in optimizing individual dosing regimens.

Comparative pharmacokinetics of polymyxin B in critically ill elderly patients with extensively drug-resistant gram-negative bacteria infections

Introduction: Elderly patients are more prone to develop acute kidney injury during infections and polymyxin B (PMB)-associated nephrotoxicity than young patients. The differential response to PMB between the elderly and young critically ill patients is unknown. We aimed to assess PMB exposure in elderly patients compared with young critically ill patients, and to determine the covariates of PMB pharmacokinetics in critically ill patients. Methods: Seventeen elderly patients (age ≥ 65 years) and six young critically ill patients (age < 65 years) were enrolled. Six to eight blood samples were collected during the 12 h intervals after at least six doses of intravenous PMB in each patient. PMB plasma concentrations were quantified by high-performance liquid chromatography-tandem mass spectrometry. The primary outcome was PMB exposure as assessed by the area under the concentration-time curve over 24 h at steady state (AUCss, 0-24 h). Results and Discussion: The elderly group had lower total body weight (TBW) and higher Charlson comorbidity scores than young group. Neither AUCss, 0-24 h nor normalized AUCss, 0-24 h (adjusting AUC for the daily dose in mg/kg of TBW) was significantly different between the elderly group and young group. The half-life time was longer in the elderly patients than in young patients (11.21 vs 6.56 h respectively, p = 0.003). Age and TBW were the covariates of half-life time (r = 0.415, p = 0.049 and r = -0.489, p = 0.018, respectively). TBW was the covariate of clearance (r = 0.527, p = 0.010) and AUCss, 0-24 h (r = -0.414, p = 0.049). Patients with AUCss, 0-24 h ≥ 100 mg·h/L had higher baseline serum creatinine levels and lower TBW than patients with AUCss, 0-24 h < 50 mg·h/L or patients with AUCss, 0-24 h 50-100 mg·h/L. The PMB exposures were comparable in elderly and young critically ill patients. High baseline serum creatinine levels and low TBW was associated with PMB overdose. Trial registration: ChiCTR2300073896 retrospectively registered on 25 July 2023.

Population pharmacokinetics of polymyxin B in patients with liver dysfunction

AIMS

Polymyxin B (PMB) is widely used to treat infections caused by multidrug-resistant Gram-negative pathogens. Currently, the pharmacokinetic data of PMB in patients with liver dysfunction are limited. This study aimed to develop a population pharmacokinetic (PopPK) model of PMB in patients with liver dysfunction and identify the factors affecting PMB pharmacokinetics.

METHODS

We conducted a retrospective pharmacokinetic study involving 136 adults with different levels of liver function. Nonlinear mixed effects modelling was used to develop a PopPK model of PMB. Monte Carlo simulation was used to design PMB dosage schedules across various liver and renal functions.

RESULTS

PMB pharmacokinetic analyses included 401 steady-state concentrations in 136 adult patients. A one-compartment pharmacokinetic model with first-order absorption and elimination was used to describe the data. The typical population value of PMB clearance was 2.43 L/h and the volume of distribution was 23.11 L. This study revealed that creatinine clearance (CrCL) and Child-Pugh class were significantly associated with PMB pharmacokinetic parameters; however, clinically relevant variations of dose-normalized drug exposure were not significant. For patients with a minimum inhibitory concentration of ≤0.5 mg/L, the appropriate dose was 40-75 mg/12-h. When the dose exceeded 100 mg/12-h, the risk of nephrotoxicity increased significantly.

CONCLUSIONS

This study provided PMB pharmacokinetic information for patients with liver dysfunction. Patients with renal and liver dysfunctions may not require an initial dose adjustment. Rather than PopPK-guided dose adjustment, therapeutic drug monitoring of PMB plays a more direct role in optimizing dosing regimens based on its therapeutic window.

Population Pharmacokinetic Modeling Using Polymyxin B Free Plasma Concentrations From Published Reports and Evaluation of Dosage Regimens Based on Monte Carlo Simulation in Critically Ill Patients

A population pharmacokinetic (pop PK) model of polymyxin B was developed using nonlinear mixed-effects (NONMEM) modeling based on free plasma concentrations to determine whether dose adjustment is required in critically ill patients. One thousand pharmacokinetic profiles for virtual patients with a body weight of 70 kg were simulated using Monte Carlo simulation at different dose scenarios, and area under the concentration-time curve of free drug (fAUC) was computed. The probability of target attainment (PTA) at each minimum inhibitory concentration (MIC) was calculated using fAUC/MIC as a pharmacokinetic/pharmacodynamic (PK/PD) index. The final population PK model was a 2-compartment model. PTA showed that 3.5 mg/kg/day regimens of polymyxin B effectively achieved the fAUC/MIC target of 10 (one log10 kill) against Pseudomonas aeruginosa strains with MIC of 1 mg/L or less (PTA,  90.7% or greater), while the dose regimen were ineffective against strains with an MIC of 2 mg/L or greater (PTA, 56.9% or less). For Klebsiella pneumoniae, the fAUC/MIC target of 17.4 (one log10 kill) was achieved in more than 90.4% of cases for MIC of 0.5 mg/L or less with 3 mg/kg/day regimens. However, the PTA decreased dramatically as MICs increased above 1 mg/L (PTA, 56.1% or less). The polymyxin B dosage regimen of 3.5 mg/kg/day and 3 mg/kg/day are sufficient to treat P. aeruginosa infections with an MIC of 1 mg/L or less and K. pneumoniae infections with an MIC of 0.5 mg/L or less, respectively. The current recommended dose (1.5-3 mg/kg/day) of polymyxin B appears inadequate to attain the PK/PD target for therapeutic efficacy against infections caused by P. aeruginosa and K. pneumoniae isolates when MIC is above the values.

Optimization of polymyxin B regimens for the treatment of carbapenem-resistant organism nosocomial pneumonia: a real-world prospective study

BACKGROUND

Polymyxin B is the first-line therapy for Carbapenem-resistant organism (CRO) nosocomial pneumonia. However, clinical data for its pharmacokinetic/pharmacodynamic (PK/PD) relationship are limited. This study aimed to investigate the relationship between polymyxin B exposure and efficacy for the treatment of CRO pneumonia in critically ill patients, and to optimize the individual dosing regimens.

METHODS

Patients treated with polymyxin B for CRO pneumonia were enrolled. Blood samples were assayed using a validated high-performance liquid chromatography-tandem mass spectrometry method. Population PK analysis and Monte Carlo simulation were performed using Phoenix NLME software. Logistic regression analyses and receiver operating characteristic (ROC) curve were employed to identify the significant predictors and PK/PD indices of polymyxin B efficacy.

RESULTS

A total of 105 patients were included, and the population PK model was developed based on 295 plasma concentrations. AUC_ss,24 h/MIC (AOR = 0.97, 95% CI 0.95-0.99, p = 0.009), daily dose (AOR = 0.98, 95% CI 0.97-0.99, p = 0.028), and combination of inhaled polymyxin B (AOR = 0.32, 95% CI 0.11-0.94, p = 0.039) were independent risk factors for polymyxin B efficacy. ROC curve showed that AUC_ss,24 h/MIC is the most predictive PK/PD index of polymyxin B for the treatment of nosocomial pneumonia caused by CRO, and the optimal cutoff point value was 66.9 in patients receiving combination therapy with another antimicrobial. Model-based simulation suggests that the maintaining daily dose of 75 and 100 mg Q12 h could achieve ≥ 90% PTA of this clinical target at MIC values ≤ 0.5 and 1 mg/L, respectively. For patients unable to achieve the target concentration by intravenous administration, adjunctive inhalation of polymyxin B would be beneficial.

CONCLUSIONS

For CRO pneumonia, daily dose of 75 and 100 mg Q12 h was recommended for clinical efficacy. Inhalation of polymyxin B is beneficial for patients who cannot achieve the target concentration by intravenous administration.

Population pharmacokinetic analysis and dosing optimization of polymyxin B in critically ill patients

Objectives: Since the global broadcast of multidrug-resistant gram-negative bacteria is accelerating, the use of Polymyxin B is sharply increasing, especially in critically ill patients. Unsatisfactory therapeutic effects were obtained because of the abnormal physiological function in critically ill patients. Therefore, the determination of optimal polymyxin B dosage becomes highly urgent. This study aimed to illustrate the polymyxin B pharmacokinetic characteristics by defining the influencing factors and optimizing the dosing regimens to achieve clinical effectiveness.

Methods: Steady-state concentrations of polymyxin B from twenty-two critically ill patients were detected by a verified liquid chromatography-tandem mass spectrometry approach. The information on age, weight, serum creatinine, albumin levels, and Acute Physiology and Chronic Health Evaluation-II (APACHE-II) score was also collected. The population PK parameters were calculated by the non-parametric adaptive grid method in Pmetrics software, and the pharmacokinetic/pharmacodynamics target attainment rate was determined by the Monte Carlo simulation method.

Results: The central clearance and apparent volume of distribution for polymyxin B were lower in critically ill patients (1.24 ± 0.38 L h-1 and 16.64 ± 12.74 L, respectively). Moreover, albumin (ALB) levels can be used to explain the variability in clearance, and age can be used to describe the variability in the apparent volume of distribution. For maintaining clinical effectiveness and lowering toxicity, 75 mg q12 h is the recommended dosing regimen for most patients suffering from severe infections.

Conclusion: This study has clearly defined that in critically ill patients, age and ALB levels are potentially important factors for the PK parameters of polymyxin B. Since older critically ill patients tend to have lower ALB levels, so higher dosages of polymyxin B are necessary for efficacy.

Evaluation and Validation of the Limited Sampling Strategy of Polymyxin B in Patients with Multidrug-Resistant Gram-Negative Infection

Polymyxin B (PMB) is the final option for treating multidrug-resistant Gram-negative bacterial infections. The acceptable pharmacokinetic/pharmacodynamic target is an area under the concentration–time curve across 24 h at a steady state (AUC_ss,24h) of 50–100 mg·h/L. The limited sampling strategy (LSS) is useful for predicting AUC values. However, establishing an LSS is a time-consuming process requiring a relatively dense sampling of patients. Further, given the variability among different centers, the predictability of LSSs is frequently questioned when it is extrapolated to other clinical centers. Currently, limited data are available on a reliable PMB LSS for estimating AUC_ss,24h. This study assessed and validated the practicability of LSSs established in the literature based on data from our center to provide reliable and ready-made PMB LSSs for laboratories performing therapeutic drug monitoring (TDM) of PMB. The influence of infusion and sampling time errors on predictability was also explored to obtain the optimal time points for routine PMB TDM. Using multiple regression analysis, PMB LSSs were generated from a model group of 20 patients. A validation group (10 patients) was used to validate the established LSSs. PMB LSSs from two published studies were validated using a dataset of 30 patients from our center. A population pharmacokinetic model was established to simulate the individual plasma concentration profiles for each infusion and sampling time error regimen. Pharmacokinetic data obtained from the 30 patients were fitted to a two-compartment model. Infusion and sampling time errors observed in real-world clinical practice could considerably affect the predictability of PMB LSSs. Moreover, we identified specific LSSs to be superior in predicting PMB AUC_ss,24h based on different infusion times. We also discovered that sampling time error should be controlled within −10 to 15 min to obtain better predictability. The present study provides validated PMB LSSs that can more accurately predict PMB AUC_ss,24h in routine clinical practice, facilitating PMB TDM in other laboratories and pharmacokinetics/pharmacodynamics-based clinical studies in the future.

Population pharmacokinetic analysis, renal safety, and dosing optimization of polymyxin B in lung transplant recipients with pneumonia: A prospective study

Objectives: This study aims to characterize the population pharmacokinetics of polymyxin B in lung transplant recipients and optimize its dosage regimens.

Patients and methods: This prospective study involved carbapenem-resistant organisms-infected patients treated with polymyxin B. The population pharmacokinetic model was developed using the NONMEM program. The clinical outcomes including clinical treatment efficacy, microbiological efficacy, nephrotoxicity, and hyperpigmentation were assessed. Monte Carlo simulation was performed to calculate the probability of target attainment in patients with normal or decreased renal function.

Results: A total of 34 hospitalized adult patients were included. 29 (85.29%) patients were considered of clinical cure or improvement; 14 (41.18%) patients had successful bacteria elimination at the end of the treatment. Meanwhile, 5 (14.71%) patients developed polymyxin B-induced nephrotoxicity; 19 (55.88%) patients developed skin hyperpigmentation. A total of 164 concentrations with a range of 0.56–11.66 mg/L were obtained for pharmacokinetic modeling. The pharmacokinetic characteristic of polymyxin B was well described by a 1-compartment model with linear elimination, and only creatinine clearance was identified as a covariate on the clearance of polymyxin B. Monte Carlo simulations indicated an adjusted dosage regimen might be needed in patients with renal insufficiency and the currently recommended dose regimens by the label sheet of polymyxin B may likely generate a subtherapeutic exposure for MIC = 2 mg/L.

Conclusion: Renal function has a significant effect on the clearance of polymyxin B in lung transplant recipients, and an adjustment of dosage was needed in patients with renal impairments.

Population pharmacokinetics of intravenous colistin sulfate and dosage optimization in critically ill patients

Aims: To explore the population pharmacokinetics of colistin sulfate and to optimize the dosing strategy for critically ill patients.

Methods: The study enrolled critically ill adult patients who received colistin sulfate intravenously for more than 72 h with at least one measurement of plasma concentration. Colistin concentrations in plasma or urine samples were measured by ultraperformance liquid chromatography tandem mass spectrometry (LC-MS/MS). The population pharmacokinetics (PPK) model for colistin sulfate was developed using the Phoenix NLME program. Monte Carlo simulation was conducted to evaluate the probability of target attainment (PTA) for optimizing dosing regimens.

Results: A total of 98 plasma concentrations from 20 patients were recorded for PPK modeling. The data were adequately described by a two-compartment model with linear elimination. During modeling, creatinine clearance (CrCL) and alanine aminotransferase (ALT) were identified as covariates of the clearance (CL) and volume of peripheral compartment distribution (V2), respectively. In addition, colistin sulfate was predominantly cleared by the nonrenal pathway with a median urinary recovery of 10.05% with large inter-individual variability. Monte Carlo simulations revealed a greater creatinine clearance associated with a higher risk of sub-therapeutic exposure to colistin sulfate. The target PTA (≥90%) of dosage regimens recommended by the label sheet was achievable only in patients infected by pathogens with MIC ≤0.5 mg/L or with renal impairments.

Conclusion: Our study showed that the dose of intravenous colistin sulfate was best adjusted by CrCL and ALT. Importantly, the recommended dosing regimen of 1.0–1.5 million units daily was insufficient for patients with normal renal functions (CrCL ≥80 ml/min) or those infected by pathogens with MIC ≥1.0 mg/L. The dosage of colistin sulfate should be adjusted according to renal function and drug exposure.

Population pharmacokinetics and clinical outcomes of polymyxin B in paediatric patients with multidrug-resistant Gram-negative bacterial infections

BACKGROUND

Current polymyxin B dosing in children relies on scant data.

OBJECTIVES

To build a population pharmacokinetic (PK) model for polymyxin B in paediatric patients and assess the likely appropriateness of different dosages.

METHODS

A total of 19 paediatric patients were enrolled to receive intravenous polymyxin B (1.33-2.53 mg/kg/day), and the median age was 12.5 (range 3.2-17.8) years. Serial plasma samples were collected at steady-state and modelled by population PK analysis. Clinical efficacy and nephrotoxicity of polymyxin B treatment were also assessed.

RESULTS

PK data were adequately described by a two-compartment model with first-order elimination, and weight was a significant covariate of polymyxin B clearance. Clinical success occurred in 14 of 19 patients (73.7%) and only one patient developed acute kidney injury. The 28 day mortality was 10.5% (2/19). The steady-state polymyxin B exposure was 36.97 ± 9.84 mg·h/L, lower than the therapeutic exposure of 50-100 mg·h/L. With the AUC24h/MIC target of 50, the dosage of 1.5-3.0 mg/kg/day had a probability of target attainments over 90% when MICs were <0.5 mg/L.

CONCLUSIONS

Dose adjustment of polymyxin B needs to consider the MIC of infecting pathogens. Current polymyxin B dosing for paediatric patients may be acceptable when MICs are <0.5 mg/L.

Population pharmacokinetics and initial dose optimization of tacrolimus in children with severe combined immunodeficiency undergoing hematopoietic stem cell transplantation

The present study aimed to explore the population pharmacokinetics and initial dose optimization of tacrolimus in children with severe combined immunodeficiency (SCID) undergoing hematopoietic stem cell transplantation (HSCT). Children with SCID undergoing HSCT treated with tacrolimus were enrolled for analysis. Population pharmacokinetics of tacrolimus was built up by a nonlinear mixed-effects model (NONMEM), and initial dose optimization of tacrolimus was simulated with the Monte Carlo method in children weighing <20 kg at different doses. A total of 18 children with SCID undergoing HSCT were included for analysis, with 130 tacrolimus concentrations. Body weight was included as a covariable in the final model. Tacrolimus CL/F was 0.36–0.26 L/h/kg from body weights of 5–20 kg. Meanwhile, we simulated the tacrolimus concentrations using different body weights (5–20 kg) and different dose regimens (0.1–0.8 mg/kg/day). Finally, the initial dose regimen of 0.6 mg/kg/day tacrolimus was recommended for children with SCID undergoing HSCT whose body weights were 5–20 kg. It was the first time to establish tacrolimus population pharmacokinetics in children with SCID undergoing HSCT; in addition, the initial dose optimization of tacrolimus was recommended.

Population Pharmacokinetics of Colistin Sulfate in Critically Ill Patients: Exposure and Clinical Efficacy

Background: Presently, colistin is commercially available in two different forms, namely, colistin sulfate and its sulphomethylated derivative, colistimethate sodium (CMS). However, in the currently reported studies, most of the clinical studies on colistin for parenteral use are referred to as CMS. Data on the pharmacokinetics (PK), clinical efficacy, and side effects of colistin sulfate in clinical use have not been reported.

Methods: This retrospective study was performed on carbapenem-resistant organism (CRO)-infected patients treated with colistin sulfate for more than 72 h. The population pharmacokinetic model was developed using the NONMEM program. The clinical outcomes including clinical treatment efficacy, microbiological eradication, and nephrotoxicity were assessed. Monte Carlo simulation was utilized to calculate the probability of target attainment (PTA) in patients with normal or decreased renal function.

Results: A total of 42 patients were enrolled, of which 25 (59.52%) patients were considered clinical treatment success and 29 (69.06%) patients had successful bacteria elimination at the end of treatment. Remarkably, no patient developed colistin sulfate-related nephrotoxicity. A total of 112 colistin concentrations with a range of 0.28–6.20 mg/L were included for PK modeling. The PK characteristic of colistin was well illustrated by a one-compartment model with linear elimination, and creatinine clearance (CrCL) was identified as a covariate on the clearance of colistin sulfate that significantly explained inter-individual variability. Monte Carlo simulations showed that the recommended dose regimen of colistin sulfate, according to the label sheet, of a daily dose of 1–1.5 million IU/day, given in 2–3 doses, could attain PTA &gt; 90% for MICs ≤ 0.5 μg/mL, and that a daily dose of 1 million IU/day could pose a risk of subtherapeutic exposure for MIC ≥1 μg/ml in renal healthy patients.

Conclusion: Renal function significantly affects the clearance of colistin sulfate. A dose of 750,000 U every 12 h was recommended for pathogens with MIC ≤1 μg/ml. The dosage recommended by the label inserts had a risk of subtherapeutic exposure for pathogens with MIC ≥2 μg/ml. Despite higher exposure to colistin in patients with acute renal insufficiency, dose reduction was not recommended.

Higher Incidence of Neurotoxicity and Skin Hyperpigmentation in Renal Transplant Patients Treated With Polymyxin B

BACKGROUND

Toxicity is a major concern related to the clinical use of polymyxin B, and available safety data for renal transplant patients are limited.

AIMS

We investigated the safety of polymyxin B and toxicity risk factors in renal transplant patients.

METHODS

A prospective study was performed on a group of renal transplant patients who received intravenous polymyxin B between January 2018 and August 2021. Polymyxin B treatment was monitored to evaluate toxicity and risk factors.

RESULTS

A total of 235 courses of polymyxin B were administered to 213 patients. Of these, 121 (51.5%) developed SH, 149 (63.4%) developed neurotoxicity, and 10 (5.5%) developed acute kidney injury of which 80% was reversible. Risk factors for developing SH included a high total dose by weight (OR=1.31, 95%CI: 1.08-1.60, p=0.008) and the presence of neurotoxicity (OR=2.86, 95%CI: 1.56-5.26, p=0.001). Neurotoxicity manifested during the first two days of treatment. Neurotoxicity occurred most commonly in women (OR=3.84, 95%CI: 1.82-8.10, p<0.0001), and the presence of SH (OR=1.98, 95%CI: 1.13-3.46, p=0.016) was also an independent risk factor.

CONCLUSIONS

Neurotoxicity and SH are the two major adverse effects of polymyxin B in renal transplant patients, which may limit its clinical use.