Population Pharmacokinetics and Loading Dose Optimization of Intravenous Valproic Acid in Hospitalized Thai Patients.

Our goal is to create a population pharmacokinetic (PK) model and identify the best loading dose (LD) of intravenous valproic acid for hospitalized Thai patients. Data from patients who received intravenous valproic acid and underwent measurement of serum valproic acid concentrations during hospitalization were collected retrospectively. A nonlinear mixed-effects modeling approach was conducted to estimate the PK parameters of valproic acid. Covariates affecting the PK parameters of valproic acid were examined and ranked based on their impact on the model's performance. Monte Carlo simulations of 1000 patients were conducted to estimate the optimal LD of valproic acid. A total of 120 hospitalized patients (51.7% male) with 167 valproic acid concentrations were included in the study. A linear one-compartment model with constant residual error was the best base model. An age-covariate model was the best predictor of valproic acid clearance (CL). The typical values of CL and volume of distribution for valproic acid were 0.77 L/h and 14.56 L, respectively. The LD of 1000-1200 mg intravenous was identified as the pragmatic option as an empirical regimen for hospitalized Thai patients. The recommended time to initiate maintenance dose (MD) is 4-8 h following the LD. The population PK model and optimal LD of valproic acid in hospitalized Thai patients has been established, and it may be advisable to initiate the MD at a later time for the elderly.

Removing race and body surface area indexation for estimated kidney function based drug dosing: Aminoglycosides as justification of these principles.

STUDY OBJECTIVE: The use of race in medicine can contribute to health inequity. Updated equations for estimated glomerular filtration rate (eGFR) without race have been published. Likewise, de-indexation of eGFR to body surface area (BSA) has been recommended by regulatory guidance for drug dosing in renal impairment. Clinical data justifying these recommendations for drug dosing are sparse. We examined the gain or loss of precision in drug dosing with estimated creatinine clearance (eCLcr) and eGFR using serum creatinine (eGFRcr) with and without race and BSA indexation by evaluating the population pharmacokinetics of the aminoglycosides as a classic drug class to probe kidney function. DESIGN: Medical records from adult patients treated with gentamicin or tobramycin over a 13-year period were queried. Population pharmacokinetic analyses were performed using a 1-compartment base structural model. Models compared body size descriptors as covariates of the volume of distribution (V). Estimated creatinine clearance and eGFRcr using multiple contemporary equations with and without BSA indexation were tested as covariates of clearance (CL). MAIN RESULTS: The final data set included 2968 patients treated with either gentamicin (20.2%) or tobramycin (79.8%). Patients self-identified as Caucasian (82%), African-American (10%), or other. The median [5th, 95th percentile] weight and BSA were 80.5 [49.4, 136] kg and 1.94 [1.48, 2.56] m2 , respectively. Models of eCLcr and eGFRcr without indexation to BSA had a better model fit than eGFRcr indexed to BSA for aminoglycoside CL. The 2021 Chronic Kidney Disease Epidemiology collaboration (CKD-EPI) eGFRcr equation (no race, no BSA indexation) provided a comparable model fit to the 2009 CKD-EPI eGFRcr equation (with race, no BSA indexation) for aminoglycoside CL. CONCLUSIONS: Race is not a relevant covariate of aminoglycoside CL. The 2021 CKD-EPI eGFR equation without race and BSA indexation is a better method for gentamicin and tobramycin CL estimation. Confirmation of these results for other drugs can support the harmonization of dosing by kidney function.

Comparison of Race-Based and Non-Race-Based Equations for Kidney Function Estimation in Critically Ill Thai Patients for Vancomycin Dosing.

Empiric antibiotic dosing frequently relies on an estimate of kidney function based on age, serum creatinine, sex, and race (on occasion). New non-race-based estimated glomerular filtration rate (eGFR) equations have been published, but their role in supporting dosing is not known. Here, we report on a population pharmacokinetic model of vancomycin that serves as a useful probe substrate of eGFR in critically ill Thai patients. Data were obtained from medical records during a 10-year period. A nonlinear mixed-effects modeling approach was conducted to estimate vancomycin parameters. Data from 208 critically ill patients (58.2% men and 36.0% septic shock) with 398 vancomycin concentrations were collected. Twenty-three covariates including 12 kidney function estimates were tested and ranked on the basis of the model performance. The median (min, max) age, weight, and serum creatinine was 69 (18, 97) years, 60.0 (27, 120) kg, and 1.53 (0.18, 7.15) mg/dL, respectively. The best base model was a 1-compartment linear elimination with zero-order input and proportional error model. A Thai-specific eGFR equation not indexed to body surface area model best predicted vancomycin clearance (CL). The typical value for volume of distribution and CL was 67.5 L and 1.22 L/h, respectively. A loading dose of 2000 mg followed by maintenance dose regimens based on eGFR is suggested. The Thai GFR not indexed to BSA model best predicts vancomycin CL and dosing in the critically ill Thai population. A 5% to 10% absolute gain in the vancomycin probability of target attainment is expected with the use of this population-specific eGFR equation.

Incidence, risk and risk factors for acute kidney injury associated with the use of intravenous indomethacin in neonatal patent ductus arteriosus: A 16-year retrospective cohort study.

Background: Intravenous indomethacin has been used in infants for many years as the pharmacological closure of ductus arteriosus, but the incidence, risk, and risk factors of acute kidney injury (AKI) among infants treated with indomethacin, were still scarce. Objectives: To determine the incidence, risk, and risk factors of AKI among infants treated with indomethacin (exposed group) for patent ductus arteriosus (PDA) closure compared with the matched non-exposed infants. Methods: A matched retrospective cohort study of infants admitted to the neonatal intensive care unit of Songklanagarind Hospital from January 2003 to December 2018 was performed. All data were collected from computerized medical records. A non-exposed infant was matched (1:1) by gestational age and birth weight to each exposed infant. AKI, the outcome of interest, was diagnosed according to neonatal AKI definitions. The incidence (95% CI) of AKI was estimated for each group. Conditional logistic regression was used to estimate the odds ratio (OR) of developing AKI among those who received indomethacin compared with those who did not, adjusted for potential confounders (concomitantly used nephrotoxic potential medications including aminoglycosides, amphotericin B, vancomycin, furosemide, systemic corticosteroids, and systemic vasopressors and inotropes). Kaplan-Meier estimate was performed to examine probability of recovery from AKI after AKI events. Results: The matching resulted in 193 pairs of exposed and non-exposed infants. The incidences [95% CI] of AKI in the exposed and the non-exposed group, were 33.7% [27.0%:40.4%] and 15.5% [10.4%:20.7%], respectively. Indomethacin statistically increased the risk for developing AKI, crude OR 2.94[95%CI 1.77:4.90], McNemar's chi square p<0.001, and adjusted OR 2.73 [95%CI 1.55:4.80], p=0.001. The risk of AKI associated with potentially nephrotoxic medications were inconclusive. Time to recovery from AKI was relatively rapid, median recovery time was 3 days in both groups and all infants who developed AKI recovered within 6 days. Conclusions: The incidence of AKI among infants treated with indomethacin for PDA closure were doubled that in the indomethacin-nonexposed infants. Indomethacin significantly increased the risk of AKI, while the risk associated with other concomitant nephrotoxic medications were inconclusive. Transient nephrotoxicity associated with indomethacin should be balanced with the risk associated with delayed PDA closure. All infants receiving indomethacin should be routinely monitored for serum creatinine and/or urine output, throughout the treatment and one to two weeks after treatment cessation. Alternatives with better renal safety profiles should be considered in the population with higher risk of AKI.

Efficacy and Safety of Enteral Erythromycin Estolate in Combination With Intravenous Metoclopramide vs Intravenous Metoclopramide Monotherapy in Mechanically Ventilated Patients With Enteral Feeding Intolerance: A Randomized, Double-Blind, Controlled Pilot Study.

BACKGROUND: In this pilot study, we aimed to determine the efficacy and safety of enteral erythromycin estolate in combination with intravenous metoclopramide compared to intravenous metoclopramide monotherapy in mechanically ventilated patients with enteral feeding intolerance. METHODS: This randomized, double-blind, controlled pilot study included 35 mechanically ventilated patients with feeding intolerance who were randomly assigned to receive 10-mg metoclopramide intravenously every 6-8 hours in combination with 250-mg enteral erythromycin estolate (study group) or placebo every 6 hours for 7 days. The primary outcome was an administered-to-target energy ratio of ≥80% at 48 hours, indicating a successful feeding. Secondary, prespecified outcomes were daily average gastric residual volume (GRV), total energy intake, administered-to-target energy ratio, hospital length of stay, in-hospital mortality, and 28-day mortality. RESULTS: The rate of successful feeding was not significantly different between the study and placebo groups (47.1% and 61.1%, respectively; P = .51). The average daily GRV was significantly lower in the study group than in the placebo group (ß = 91.58 [95% Wald CI, -164.35 to -18.8]), determined by generalized estimating equation. Other secondary outcomes were comparable, and the incidence of adverse events was not significantly different between the 2 groups. One common complication was cardiac arrhythmia, which was mostly self-terminated. CONCLUSION: Although the combination therapy of enteral erythromycin estolate and intravenous metoclopramide reduced GRV, the successful feeding rate and other patient-specific outcomes did not improve in mechanically ventilated patients with feeding intolerance.