Polymyxin B Dosing and Administration in Critical Care

Standard Dosing Regimen

• The standard dosing regimen for critical care patients with normal renal function is 2.5-3.0 mg/kg/day divided into 2 daily intravenous doses, preceded by a loading dose of 2-2.5 mg/kg to rapidly achieve therapeutic plasma concentrations, as recommended by the Infectious Diseases Society of America 1

Combination Therapy Approach

• Polymyxin B should be used in combination therapy rather than monotherapy for carbapenem-resistant infections, according to the Clinical Infectious Diseases guidelines 3
• When treating ventilator-associated pneumonia with suspected multidrug-resistant gram-negative pathogens, combine polymyxin B with an antipseudomonal β-lactam agent, such as piperacillin-tazobactam, cefepime, or meropenem, as recommended by the Infectious Diseases Society of America 1

Nephrotoxicity Risk Management

• Polymyxin B has significantly lower nephrotoxicity compared to colistin, with an incidence of 11.8% vs 39.3%, according to the Praxis Medical Insights guidelines 4
• Avoid concurrent nephrotoxic agents, such as aminoglycosides, NSAIDs, diuretics, and ACE inhibitors/ARBs, to minimize the risk of nephrotoxicity, as recommended by the Praxis Medical Insights guidelines 2, 3

Therapeutic Drug Monitoring

• Target a steady-state average concentration of approximately 3.35 mg/L, with an optimal AUCss,24h of 50-100 mg·h/L, as recommended by the Praxis Medical Insights guidelines 2

Special Considerations

• Do not reduce doses in renal impairment, as this contradicts older FDA labeling but is supported by current pharmacokinetic evidence, according to the Praxis Medical Insights guidelines 2
• Do not omit the loading dose, as failure to load results in subtherapeutic levels for the first 24-48 hours, according to the Praxis Medical Insights guidelines 2
• Do not confuse polymyxin B with colistin dosing, as they have different unit conversions and dosing requirements, according to the Praxis Medical Insights guidelines 3
• Do not use as monotherapy for carbapenem-resistant infections when combination therapy is feasible, according to the Praxis Medical Insights guidelines 3