Standards of aminoglycoside therapeutic drug monitoring in a South African private hospital: perspectives and implications

Appropriateness of gentamicin therapeutic drug monitoring at a Middle Eastern tertiary hospital setting: a retrospective evaluation and quality audit

Introduction

The use of gentamicin in the treatment of infectious diseases requires frequent monitoring to attain the best treatment outcomes.

Objective

This study aimed to evaluate the appropriateness of gentamicin therapeutic drug monitoring (TDM) at a tertiary care hospital in Qatar.

Methods

A one-year quantitative retrospective chart review of all gentamicin TDM records was conducted. Evidence-based criteria were applied to evaluate the appropriateness of gentamicin TDM in terms of indication, sampling times, and post-analytical actions.

Results

Out of 59 captured gentamicin TDM records, 58 gentamicin samples were eligible for evaluation. Overall, gentamicin TDM appropriateness was achieved in 50% (n = 29) of the evaluated records. However, 12% (n = 7) of gentamicin drug concentrations were below the assay quantification limits or were not sampled appropriately. Inappropriate post-analytical actions (22.4%, n = 13) and inappropriate sampling times (44.8%, n = 26) were recorded. Most of the gentamicin blood samples (n = 43; 74.2%) were taken appropriately at steady-state. Inappropriate sampling time relative to the last dose was captured in 31% (n = 18) of the cases. Although 27.6% (n = 16) of gentamicin concentrations were non-therapeutic, continuing gentamicin dosing without adjustment was the most frequent post-analytical action (69.8%, n = 37). Gentamicin dose regimen continuations, dose regimen decreases and dose regimen discontinuations were inappropriately applied in 27% (n = 10), 25% (n = 2) and 14% (n = 1) of the times, respectively.

Conclusion

Suboptimal gentamicin TDM practices exist in relation to sampling time and post-analytical actions. Studies exploring setting-specific reasons behind inappropriate TDM practices and methods of its optimisation are needed.

A Real-World Data Derived Pharmacovigilance Assessment on Drug-Induced Nephropathy: Implication on Gaps in Patient Care

This retrospective cross-sectional study aims to investigate the prevalence and seriousness of drug-induced nephrotoxicity and to identify clinical predictors intensifying the seriousness of nephrotoxicity. Adverse drug events (ADEs) reported to the Korean Adverse Event Reporting System Database (KAERS DB) from January 2012 to December 2021 were investigated. The association between the seriousness and the etiologic drug was estimated in reporting odds ratio (ROR) based on disproportionality analysis. Logistic regression was utilized to recognize predictors associated with serious nephrotoxicity. The majority of ADEs were reported in ages 30 to 59, and immunosuppressants were the most etiologic medications. ADEs involving antibiotics, including vancomycin (ROR 0.268; 95% CI 0.129-0.557), were less likely to be serious. More than 93% of cyclosporine-related ADEs were serious nephrotoxicity, whereas tacrolimus was less likely to report serious nephrotoxicity (ROR 0.356; 95% CI 0.187-0.680). The risk of serious nephrotoxicity was decreased with aging (ROR 0.955; 95% CI 0.940-0.972) while increased in women (OR 2.700; 95% CI 1.450-5.008). Polypharmacy was associated with increased risk of interstitial nephritis (OR 1.019; 95% CI 1.001-1.038). However, further studies investigating the impact of clinical practice on ADE incidences as well as clinical prognosis related to nephrotoxicity are obligated.

Review on Population Pharmacokinetics of Amikacin in Paediatrics

Amikacin is an aminoglycoside antibiotic with a broad-spectrum bacterial coverage that is frequently utilized both as monotherapy and in combination with other antibiotics for severe bacterial infections in the paediatric population. The narrow therapeutic index of the drug and high inter-individual variabilities in drug exposure results in either drug toxicity or subtherapeutic concentrations. Thus, therapeutic drug monitoring and population pharmacokinetics are pivotal to facilitate the optimal dosage regimens in paediatrics and negate the adverse outcomes. The therapeutic goal is to maintain the target peak and trough concentrations within 30-40mg/l and <5 mg/l respectively. This review aimed to summarize population pharmacokinetic considerations and the pharmacokinetic parameters of amikacin across the paediatric population.

Utility, promise, and limitations of liquid chromatography-mass spectrometry-based therapeutic drug monitoring in precision medicine

Therapeutic drug monitoring (TDM) is typically referred to as the measurement of the concentration of drugs in patient blood. Although in the past, TDM was restricted to drugs with a narrow therapeutic range in order to avoid drug toxicity, TDM has recently become a major tool for precision medicine being applied to many more drugs. Through compensating for interindividual differences in a drug's pharmacokinetics, improved dosing of individual patients based on TDM ensures maximum drug effectiveness while minimizing side effects. This is especially relevant for individuals that present a particularly high intervariability in pharmacokinetics, such as newborns, or for critically/severely ill patients. In this article, we will review the applications for and limitations of TDM, discuss for which patients TDM is most beneficial and why, examine which techniques are being used for TDM, and demonstrate how mass spectrometry is increasingly becoming a reliable and convenient alternative for the TDM of different classes of drugs. We will also highlight the advances, challenges, and limitations of the existing repertoire of TDM methods and discuss future opportunities for TDM-based precision medicine.

High-throughput identification and determination of aminoglycoside antibiotics in human plasma using UPLC-Q-ToF-MS

Aminoglycosides are a class of broad-spectrum antibiotics with several clinical uses. Owing to the ototoxicity and nephrotoxicity of aminoglycosides, therapeutic drug monitoring is required. This study aimed to devise a high-throughput method for identification and quantitative determination of aminoglycoside antibiotics in human plasma samples using ultra-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UPLC-Q-ToF-MS). Plasma samples (100 µL) spiked with five aminoglycosides (streptomycin, spectinomycin, amikacin, kanamycin, and gentamycin) and an internal standard (ribostamycin) were diluted and centrifuged in aqueous formic acid and acetonitrile. The clear supernatant extract was evaporated and reconstituted in the mobile phase, of which 4 µL was subjected to UPLC-Q-ToF-MS. Prominent peaks were observed for the drugs within 3 min. The recoveries of five aminoglycosides from plasma samples were 92.6-120%. The regression equations showed excellent linearity (0.9999 ≥ r² ≥ 0.9987) within the range of 1.0-100 µg/mL, and detection limits of 0.5-2.0 µg/mL. The coefficients of the intra- and inter-day variations for five drugs were less than 11.8%, while the accuracy of quantitation was in the range of 89-111%. In this study, a novel method was presented for identification and determination of aminoglycosides in human plasma samples using UPLC-Q-ToF-MS analysis. This method can be applied to high-throughput analysis used for clinical and environmental purposes.

Evaluation of Assays to Measure Aminoglycosides in Serum: Comparison of Accuracy and Precision Based on External Quality Assessment

BACKGROUND

Aminoglycosides require highly accurate therapeutic drug monitoring owing to their narrow therapeutic windows and toxic side effects. Therapeutic drug monitoring varies in different laboratories, and this difference is mainly due to the use of different analytical techniques. This study aimed to compare the accuracy and precision of immunoassays for the measurement of gentamicin, tobramycin, and amikacin in serum.

METHODS

Human plasma samples were spiked with known concentrations of amikacin, gentamicin, and tobramycin and dispatched to laboratories worldwide. The percentage deviation and coefficient of variation were calculated to compare the accuracy and precision among immunoassays and among antibiotics.

RESULTS

We analyzed 273, 534, and 207 amikacin, gentamicin, and tobramycin measurement results, obtained satisfactory rates of 83.9%, 86.3%, and 93.7%, and coefficients of variation ranging from 1.1% to 15.6%, 2.9% to 25.2%, and 1.8% to 27.0%, respectively. The percentage deviation ranged from -7.5% to 6.6%, -20.8% to 18.7%, and -33.2% to 41.5% for amikacin, gentamicin, and tobramycin, respectively. Significant differences were observed in accuracy and precision among assays for all antibiotics.

CONCLUSIONS

This study demonstrated high variations in results obtained from antibiotic assays conducted at different laboratories worldwide.