Evaluation of predictability for vancomycin dosage regimens by the Bayesian method with Japanese population pharmacokinetic parameters

[Forty-three Years of Dedicated Efforts in Advancing Pharmacist Expertise: Aspiring to Become a Pharmacist and Cultivate Pharmacists Proficient in Recommending Prescription Medicines to Doctors]

When I graduated from university, my aim was to become a pharmacist capable of recommending prescription medicines to doctors and teaching others to do the same. To achieve this goal, I developed comprehensive curricula incorporating progressive educational tools such as problem-based learning and small group discussions. Subsequently, the effectiveness of these tools and curricula was evaluated, and the findings of these assessments were published in various peer-reviewed journal articles. Consequently, a body of evidence on the most effective ways to recommend prescription medicines to doctors was gradually established. This paper aims to summarize this comprehensive body of research spanning over 43 years, with the objective of highlighting the valuable insights gained thus far, identifying the best practice techniques, and exploring potential avenues for future research.

Clinical Practice Guidelines for Therapeutic Drug Monitoring of Vancomycin in the Framework of Model-Informed Precision Dosing: A Consensus Review by the Japanese Society of Chemotherapy and the Japanese Society of Therapeutic Drug Monitoring

Background: To promote model-informed precision dosing (MIPD) for vancomycin (VCM), we developed statements for therapeutic drug monitoring (TDM). Methods: Ten clinical questions were selected. The committee conducted a systematic review and meta-analysis as well as clinical studies to establish recommendations for area under the concentration-time curve (AUC)-guided dosing. Results: AUC-guided dosing tended to more strongly decrease the risk of acute kidney injury (AKI) than trough-guided dosing, and a lower risk of treatment failure was demonstrated for higher AUC/minimum inhibitory concentration (MIC) ratios (cut-off of 400). Higher AUCs (cut-off of 600 μg·h/mL) significantly increased the risk of AKI. Although Bayesian estimation with two-point measurement was recommended, the trough concentration alone may be used in patients with mild infections in whom VCM was administered with q12h. To increase the concentration on days 1–2, the routine use of a loading dose is required. TDM on day 2 before steady state is reached should be considered to optimize the dose in patients with serious infections and a high risk of AKI. Conclusions: These VCM TDM guidelines provide recommendations based on MIPD to increase treatment response while preventing adverse effects.

Preventive effect of 20 mEq and 8 mEq magnesium supplementation on cisplatin-induced nephrotoxicity: a propensity score-matched analysis

PURPOSE

The protective effect of magnesium (Mg) supplementation against cisplatin (CDDP)-induced nephrotoxicity has been widely described; however, the optimal dose of Mg supplementation is unclear. The aim of this study was to investigate whether 20 mEq of Mg supplementation is more effective than 8 mEq Mg in preventing CDDP-induced nephrotoxicity, as well as the associated risk factors, in cancer patients treated with CDDP-based chemotherapy.

METHODS

Pooled data of 272 patients receiving 20 mEq or 8 mEq Mg supplementation to CDDP-based chemotherapy from a multicenter, retrospective, observational study were compared using propensity score matching. Separate multivariate logistic regression analyses were used to identify the risk factors for renal failure induced by each treatment dose.

RESULTS

There was no significant difference in the incidence of nephrotoxicity between the 8 mEq and 20 mEq groups (P = 0.926). There was also no significant difference in the severity of nephrotoxicity, elevated serum creatinine levels, and decreased estimated creatinine clearance levels between the two groups. Cardiac disease and albumin levels were identified as independent risk factors for CDDP-induced nephrotoxicity.

CONCLUSION

We did not find an advantage of 20 mEq over 8 mEq Mg supplementation in terms of a preventive effect against CDDP-induced nephrotoxicity. The optimal dose of Mg supplementation for the prevention of CDDP-induced nephrotoxicity remains unknown, and further studies are warranted.

Risk Factors for Cisplatin-Induced Nephrotoxicity: A Multicenter Retrospective Study

INTRODUCTION

Cisplatin (CDDP)-induced nephrotoxicity is a concern in CDDP-based chemotherapy. The goal of this multicenter retrospective study was to identify potential risk factors for CDDP nephrotoxicity.

METHODS

Clinical data were reviewed for 762 patients who underwent chemotherapy including CDDP ≥60 mg/m2 per day from Spring 2014 to September 2016. CDDP nephrotoxicity was defined according to the National Cancer Institute Common Terminology Criteria for Adverse Events for acute kidney injury. Univariate and multivariate logistic regression analyses were performed to identify risk factors for CDDP nephrotoxicity.

RESULTS

CDDP nephrotoxicity was observed in 165 patients (21.7%). Multivariate analysis showed a significantly higher rate of CDDP nephrotoxicity in patients with cardiac disease (odds ratio [OR]: 2.05, 95% confidence interval [CI]: 1.07-3.93, p = 0.03), hypertension (OR: 1.57, 95% CI: 1.06-2.32, p = 0.02), and high-dose CDDP therapy (OR: 2.15, 95% CI: 1.50-3.07, p < 0.01). Magnesium (Mg) supplementation (OR: 0.65, 95% CI: 0.45-0.93, p = 0.02) and diuretic use (OR: 0.22, 95% CI: 0.08-0.63, p < 0.01) were also independent risk factors for CDDP nephrotoxicity.

CONCLUSIONS

Our results suggest that high-dose CDDP and comorbidities of cardiac disease and hypertension are independent risk factors for CDDP nephrotoxicity. Therefore, close monitoring of serum creatinine values during CDDP treatment is recommended for patients with these risk factors. In addition, Mg supplementation and administration of diuretics might be effective for prevention of CDDP nephrotoxicity.

Augmented Renal Clearance of Vancomycin in Hematologic Malignancy Patients

The pharmacokinetics of vancomycin (VAN) was retrospectively examined based on trough concentrations at large scale to identify pharmacokinetic differences between Japanese hematologic malignancy and non-malignancy patients. Data from 261 hematologic malignancy patients and 261 non-malignancy patients, including the patient's background, VAN dose, and pharmacokinetics of VAN estimated by an empirical Bayesian method, were collected and analyzed. Our results showed significantly higher values for VAN clearance and shorter elimination half-lives in patients with hematologic malignancies than non-malignancy patients. In addition, multiple regression analysis under adjusting for confounding factors by propensity score, showed that VAN clearance significantly increased in relation to hematologic malignancies. In conclusion, since in hematologic cancer patients VAN clearance is increased, the blood concentration of VAN becomes lower than expected and this may contribute to the survival of resistant bacteria when VAN is administered at low doses. These results suggest that early monitoring of VAN levels in hematologic cancer patients might be recommended to maintain desired effects without side-effects.

Risk Factors Associated with Cisplatin-Induced Nephrotoxicity in Patients with Advanced Lung Cancer

Cisplatin (CDDP) combination chemotherapy is widely administered to patients with advanced lung cancer. The dose depends on multiple factors, including whether the tumor is non-small-cell lung cancer (NSCLC) or small-cell lung cancer (SCLC). Although efficacy is limited by cisplatin-induced nephrotoxicity (CIN), little is known about the risk factors for this complication. The aim of this study was to identify the risk factors for CIN in patients with advanced lung cancer, both NSCLC and SCLC. We retrospectively reviewed clinical data for 148 patients who underwent initial chemotherapy including CDDP ≥50 mg/m² per patient per day for the first course at Kyushu Medical Center between October 2010 and September 2013. All data were collected from the electronic medical record system. Nephrotoxicity was defined as an increase in serum creatinine concentration of at least grade 2 during the first course of CDDP chemotherapy, as described by the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0. CIN was observed in nine patients. Univariate analysis revealed that cardiac disease and lower baseline serum albumin (Alb) values conferred a higher risk of nephrotoxicity (p<0.05). The cut-off value of Alb was 3.8 g/dL, calculated by receiver operating characteristics (ROC) curves. Multivariable logistic regression analysis revealed that cardiac disease (odds ratio=11.7; p=0.002) and hypoalbuminemia (odds ratio=6.99 p=0.025 significantly correlated with nephrotoxicity. In conclusion, cardiac disease and low baseline Alb values are possible risk factors for CIN.

Duration of Systemic Inflammatory Response Syndrome Influences Serum Vancomycin Concentration in Patients With Sepsis

PURPOSE

Vancomycin (VCM) is used in the treatment of methicillin-resistant Staphylococcus aureus infection. The dosage of VCM must be adjusted by using therapeutic drug monitoring because of the drug's narrow therapeutic concentration window. Although optimal administration based on population pharmacokinetic (PPK) analysis and/or a Bayesian method has improved prediction accuracy, serum concentrations of VCM in patients with sepsis often deviate significantly from predicted values. We investigated factors influencing prediction errors with PPK analysis in VCM dosing.

METHODS

This retrospective cohort study included patients treated with VCM. Their clinical data were recorded, and there were 27 nonseptic patients and 68 septic patients. VCM concentrations were predicted by using PPK analysis and data compared with observed concentrations.

FINDINGS

Patients with sepsis had a higher mean absolute error than nonseptic patients, indicating a deviation of VCM concentrations from predicted values in the septic patients. To determine factors influencing prediction errors, we classified patients with sepsis into 3 subgroups according to the mean absolute error value (2.17) for the nonseptic patients: "lower" group (prediction errors, below -2.17), "upper" group (>2.17), and "no change" group (-2.17 to 2.17). In a comparison of clinical characteristics of the 3 groups, significant differences were found in the duration of systemic inflammatory response syndrome (SIRS), SIRS score, disseminated intravascular coagulation score, and levels of creatinine clearance (CrCl), hemoglobin, and diastolic blood pressure. Multiple logistic regression analysis identified SIRS duration and CrCl as factors associated with VCM concentrations in the lower and/or upper groups of septic patients. Shorter and longer SIRS duration were associated with VCM concentrations in the lower group and the upper group, respectively, compared with predicted values in patients with sepsis. According to receiver-operating characteristic curve analysis, the optimal cutoff value of SIRS duration for the lower group was 2 days; for the upper group, it was 6 days. VCM clearance in patients with an SIRS duration <2 days was higher than that for patients with an SIRS duration ≥6 days.

IMPLICATIONS

SIRS duration was identified as influencing VCM concentration in patients with sepsis. This study has 2 limitations. First, we performed blood sampling only for trough concentrations. Repeated blood sampling for both peak and trough concentrations should be performed for more accurate pharmacokinetic evaluation in critically ill patients. Second, we determined CrCl by using the Cockcroft-Gault formula, which may not be accurate in critically ill patients. Modifying VCM dosing according to SIRS duration will improve prediction accuracy of VCM concentration based on therapeutic drug monitoring.

A retrospective analysis of vancomycin pharmacokinetics in Japanese cancer and non-cancer patients based on routine trough monitoring data

The pharmacokinetics of vancomycin was retrospectively examined based on trough concentrations obtained during routine therapeutic drug monitoring to examine possible pharmacokinetic differences between adult Japanese cancer and non-cancer patients with various degrees of renal function. A total of 231 data points from 65 cancer patients and 41 non-cancer patients were collected, and patients' background, vancomycin dose, and vancomycin clearance estimated by an empirical Bayesian method were summarized. Regarding the patients' characteristics and clinical laboratory test data, no clear differences were found between the two groups. The relationship between vancomycin clearance and creatinine clearance were similar between the groups, suggesting little effect of malignancy on vancomycin clearance. After the sub-group comparisons regarding fluid retention and cancer type, no clear differences were found in the vancomycin clearance versus creatinine clearance relationship. We conclude that the initial dose of vancomycin should not necessarily be adjusted for cancer patients. For individualized vancomycin-based therapy, dose adjustment at the appropriate time is important according to information from routine therapeutic drug monitoring and clinical laboratory tests, and to observations of the efficacy, nephrotoxicity, and other conditions in each patient.

Serum cystatin C as a better marker of vancomycin clearance than serum creatinine in elderly patients

OBJECTIVES

The purpose of this study is to assess the usefulness of the concentration of cystatin C (Cys-C) in serum for predicting the clearance of vancomycin (CLvcm) compared with the serum concentration of creatinine (SCr) in the elderly.

METHODS

Thirty-nine serum samples were obtained from 24 elderly patients (65 years and older). Creatinine clearance (CLcr) and the glomerular filtration rate calculated from the concentration of Cys-C (GFRcys-c) were estimated using Cockcroft & Gault's formula and Larsson's formula, respectively.

RESULTS

The correlation constant for CLvcm and the reciprocal of Cys-C (p=0.883) was significantly higher than that for CLvcm and the reciprocal of SCr (p=0.575, p<0.005). GFRcys-c was strongly correlated with CLvcm (p=0.883) and the constant was significantly higher than that for the correlation between CLvcm and CLcr (p=0.684, p<0.05). These results suggest that the serum concentration of Cys-C is a more reliable marker for predicting CLvcm than is SCr in elderly patients.

Evaluation of Clinical Efficacy of Maeda’s Nomogram for Vancomycin Dosage Adjustment in Adult Japanese MRSA Pneumonia Patients

The clinical efficacy of Maeda's nomogram for vancomycin dosage adjustment was evaluated by comparison with a standard dosage regimen (package insert information: vancomycin dose reduced in elderly patients and patients with renal dysfunction, with Moellering's nomogram used for renal-dysfunction patients) in adult Japanese MRSA pneumonia patients. Using Maeda's nomogram, the vancomycin dose is fixed at 1,000 mg while the dosing interval is varied in accordance with individual creatinine clearance. Using a standard dosage regimen, 5 patients out of 27 (18.5%) achieved target plasma levels of vancomycin (25-40 microg/mL for peak and 5-15 microg/mL for trough) within 2-6 days. Using Maeda's nomogram, 38 patients out of 53 (71.7%) achieved target levels in that time. A higher clinical response (complete resolution of all signs and symptoms of MRSA infection) to vancomycin therapy was also obtained with Maeda's nomogram when evaluated approximately 2-weeks after discontinuation of vancomycin therapy (43.4% versus 18.5% for the standard regimen). In conclusion, the Maeda's nomogram regimen with a 1,000 mg vancomycin dose was shown to achieve target plasma levels of vancomycin at a higher rate and provide higher clinical efficacy in vancomycin therapy of MRSA pneumonia patients, as compared with the currently available standard dosage regimen.