Population Pharmacokinetics with Monte Carlo Simulations of Gentamicin in a Population of Severely Ill Adult Patients from Sub-Saharan Africa.

In sub-Saharan Africa (SSA), gentamicin is commonly used for severe infections in non-intensive-care-unit (ICU) settings, but pharmacokinetic and pharmacodynamic data for this specific population are lacking. We performed a population pharmacokinetic study in an adult Mozambican non-ICU hospital population treated with gentamicin (n = 48) and developed a pharmacokinetic model using nonlinear mixed-effects modeling. Simulations showed that non-ICU patient populations in SSA may be at substantial risk for underexposure to gentamicin during routine once-daily dosing.

Pharmacokinetics and pharmacodynamic target attainment of ceftriaxone in adult severely ill sub-Saharan African patients: a population pharmacokinetic modelling study.

Background: In sub-Saharan Africa (SSA), the highly albumin-bound ß-lactam ceftriaxone is frequently used for the empirical treatment of severe bacterial infections. Systemic drug exposure of ß-lactams can be altered in critically ill ICU patients, but pharmacokinetic and pharmacodynamic data for non-ICU SSA populations are lacking. Methods: We performed a population pharmacokinetic study in an adult hospital population in Mozambique, treated with ceftriaxone for presumptive severe bacterial infection from October 2014 to November 2015. Four blood samples per patient were collected for total ceftriaxone (CEFt) and unbound ceftriaxone (CEFu) concentration measurement. We developed a population pharmacokinetic model through non-linear mixed effect analysis and performed simulations for different patient variable, dosing and pharmacodynamic target scenarios. Results: Eighty-eight participants yielded 277 CEFt and 276 CEFu concentrations. The median BMI was 18.9 kg/m2 and the median albumin concentration was 29 g/L. In a one-compartment model with non-linear protein binding, creatinine clearance was positively correlated with CEFu clearance. For microorganisms with an MIC of 1 mg/L, simulations demonstrated that with a 1 g twice-daily regimen and a 2 g once-daily regimen, 95.1% and 74.8% would have a CEFu concentration > MIC during half of the dosing interval (fT>MIC = 50%), respectively, whereas this was only 58.2% and 16.5% for the fT>MIC = 100% target. Conclusions: Severely ill adult non-ICU SSA patients may be at substantial risk for underexposure to CEFu during routine intermittent bolus dosing, especially when their renal function is intact.

Pharmacokinetics and Pharmacodynamic Target Attainment of Benzylpenicillin in an Adult Severely Ill Sub-Saharan African Patient Population.

Background: In intensive care (ICU) patients, systemic exposure of ß-lactam antibiotics can be altered, and positive clinical outcome is associated with increasing fT > MIC ratios. In sub-Saharan African hospitals, benzylpenicillin (PEN) is frequently used for the empiric treatment of severe pneumococcal infections. Pharmacokinetic data for non-ICU hospitalized populations are lacking. Methods: We performed a population pharmacokinetic (PPK) study in an adult Mozambican hospital population treated intravenously with PEN from October 2014 through November 2015. Four blood samples/patient were collected for total PEN (PENt) and unbound PEN (PENu) concentration measurement. We developed a PPK model through nonlinear mixed-effects analysis and performed simulations for different patient variable, dosing, and pharmacodynamic target scenarios. Results: One hundred twelve participants yielded 387 PENt and 53 PENu concentrations. The median body mass index was 18.3 (range, 10.5-31.3) kg/m2 and the median albumin concentration and creatinine clearance (CrCl) were 29 (range, 12-44) g/L and 80 (range, 3-195) mL/minute, respectively. In a 1-compartment model, CrCl was positively correlated with PENt clearance. For infections with a microorganism with a minimum inhibitory concentration (MIC) of 1 mg/L, simulations demonstrated that with 3 million IU (1.8 g) every 6 hours, 74.1% would have a PENu concentration greater than the MIC during half of the dosing interval (fT > MIC = 50%), whereas this was 24.8% for the fT > MIC = 100% target. For pathogens with an MIC of 0.06 mg/L, these percentages were 98.2% and 72.3%, respectively. Conclusions: Severely ill adult sub-Saharan African patients may be at high risk for underexposure to PENu during routine intermittent bolus dosing, especially when their renal function is intact and when infected with pathogens with intermediate susceptibility.