Reduction of linezolid-associated thrombocytopenia by the dose adjustment based on the risk factors such as basal platelet count and body weight

Using Machine Learning to Predict Linezolid-Associated Thrombocytopenia

Objective

Using artificial intelligence and machine learning to predict linezolid-induced thrombocytopenia helps identify related risk factors in patients.

Methods

Between January 2020 and December 2023, 284 patients receiving linezolid from Beijing Chaoyang Hospital were enrolled. The data underwent filtering to ensure completeness and quality. The filtered data were then randomly divided into training and validation sets at a 3:1 ratio using stratified sampling. Four machine learning methods-logistic regression, Lasso regression, support vector machine (SVM), and random forest-were employed to develop predictive models on the training set, with optimal hyperparameters determined through grid search. Model performance was assessed via 10 - fold cross - validation on the training set, and the model with the highest AUC was selected. The chosen model was further validated on the independent validation set, with AUC, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) calculated.

Results

During treatment with linezolid, 42 (14.8%) of the 284 patients developed thrombocytopenia, with an average onset of 12.0±5.6 days after starting linezolid therapy. The random forest model demonstrated the best performance, with an AUC of 0.902 (95% CI 0.814-0.991) in the validation set. This model achieved a sensitivity of 81.8%, specificity of 86.9%, positive predictive value (PPV) of 52.9%, and negative predictive value (NPV) of 96.4%.

Conclusion

We developed a machine learning model to predict linezolid-associated thrombocytopenia, with the random forest model achieving an AUC of 0.902. This model can help clinicians assess patient risk and optimize treatment plans. Future work should validate the model in multicenter studies and explore its integration into clinical decision support systems.

Personalized Dosing of Linezolid to Reduce the Risk of Thrombocytopenia: A Systematic Review and Meta-Analysis

BACKGROUND

Linezolid-induced thrombocytopenia (LIT) occurs in a dose-dependent manner. There is no consensus regarding personalized dosing of linezolid in the real world. This study investigated the usefulness of personalized dosing for the potential mitigation of LIT compared with standard dosing.

METHODS

A systematic review and meta-analysis were performed using 4 medical electronic databases. Inclusion criteria were original research articles published up to October 23, 2023, whereas nonoriginal articles were excluded. Eligible participants included adults who were administered linezolid. A random-effects model was used to synthesize the results.

RESULTS

Four studies were eligible for inclusion. There were 208 patients in the personalized dosing (intervention) group and 195 patients in the standard dosing (comparison) group. The odds ratio for the intervention was 0.648 (95% confidence interval: 0.150-2.797), although significant heterogeneity was observed (I2 = 83.3%). An ad hoc analysis was performed by excluding one study with a significant bias risk in the treatment duration. The odds ratio for the intervention in the ad hoc analysis was 0.356 (95% confidence interval: 0.179-0.708) with little heterogeneity, showing a lower incidence risk of LIT.

CONCLUSIONS

Personalized dosing in linezolid therapy may mitigate the risk of LIT.

Prediction of risk factors for linezolid-induced thrombocytopenia based on neural network model

Background: Based on real-world medical data, the artificial neural network model was used to predict the risk factors of linezolid-induced thrombocytopenia to provide a reference for better clinical use of this drug and achieve the timely prevention of adverse reactions. Methods: The artificial neural network algorithm was used to construct the prediction model of the risk factors of linezolid-induced thrombocytopenia and further evaluate the effectiveness of the artificial neural network model compared with the traditional Logistic regression model. Results: A total of 1,837 patients receiving linezolid treatment in a hospital in Xi 'an, Shaanxi Province from 1 January 2011 to 1 January 2021 were recruited. According to the exclusion criteria, 1,273 cases that did not meet the requirements of the study were excluded. A total of 564 valid cases were included in the study, with 89 (15.78%) having thrombocytopenia. The prediction accuracy of the artificial neural network model was 96.32%, and the AUROC was 0.944, which was significantly higher than that of the Logistic regression model, which was 86.14%, and the AUROC was 0.796. In the artificial neural network model, urea, platelet baseline value and serum albumin were among the top three important risk factors. Conclusion: The predictive performance of the artificial neural network model is better than that of the traditional Logistic regression model, and it can well predict the risk factors of linezolid-induced thrombocytopenia.

Risk factors for thrombocytopenia in patients receiving linezolid therapy: a systematic review and meta-analysis

PURPOSE

The incidence of linezolid-induced thrombocytopenia (LIT) has been reported to vary widely across studies. We performed a meta-analysis to identify the risk factors for thrombocytopenia among patients who received linezolid treatment.

METHODS

The PubMed, Embase and Cochrane Library databases were searched from inception to November 2022 to identify eligible studies. Data on the potential predictors of incidence in LIT were pooled using a random effects model. Sensitivity analyses were performed to determine the robustness of the results when significant heterogeneity was observed.

RESULTS

Forty observational studies involving 6454 patients treated with linezolid were included in the analysis. LIT was estimated to occur in 37% of patients. The following important factors were associated with the incidence of LIT: advanced age, body mass index, concurrent renal impairment or liver disease, abnormal laboratory parameters (including white blood cell count, serum creatinine, baseline platelet count, albumin, creatinine clearance rate, and estimated glomerular filtration rate), treatment duration and renal replacement therapy.

CONCLUSIONS

A variety of risk factors related to the occurrence of LIT were revealed in our analysis. Early identification of these factors could help patients improve clinical outcomes.

Therapeutics for Vancomycin-Resistant Enterococcal Bloodstream Infections

Vancomycin-resistant enterococci (VRE) are common causes of bloodstream infections (BSIs) with high morbidity and mortality rates. They are pathogens of global concern with a limited treatment pipeline. Significant challenges exist in the management of VRE BSI, including drug dosing, the emergence of resistance, and the optimal treatment for persistent bacteremia and infective endocarditis. Therapeutic drug monitoring (TDM) for antimicrobial therapy is evolving for VRE-active agents; however, there are significant gaps in the literature for predicting antimicrobial efficacy for VRE BSIs. To date, TDM has the greatest evidence for predicting drug toxicity for the three main VRE-active antimicrobial agents daptomycin, linezolid, and teicoplanin. This article presents an overview of the treatment options for VRE BSIs, the role of antimicrobial dose optimization through TDM in supporting clinical infection management, and challenges and perspectives for the future.

Hematological toxicities associated with linezolid therapy in adults: key findings and clinical considerations

INTRODUCTION

Linezolid can cause serious adverse effects including thrombocytopenia and anemia. Here, we focus specifically on linezolid-related hematological toxicity in adult patients requiring prolonged drug treatment.

AREAS COVERED

We review the available evidence on the likelihood of hematological toxicity in adult patients treated with linezolid, with a focus on the main risk factors and strategies to prevent this adverse event. A MEDLINE PubMed search for articles published from January 2000 to May 2022 was completed matching the terms linezolid, hematology, hematological toxicity, anemia, and thrombocytopenia. Moreover, additional studies were identified from the reference lists of retrieved articles.

EXPERT OPINION

Thrombocytopenia is the major concern with administration of linezolid for Gram-positive infections, whereas anemia is more common in patients with tuberculosis. The important clinical risk factors for the development of linezolid-related thrombocytopenia are aging, renal dysfunction, low baseline platelet count, duration of treatment, and linezolid plasma trough concentrations >8 mg/L. Patients receiving linezolid for extended periods of time or patient populations with increased risk of altered drug pharmacokinetics would benefit from therapeutic drug monitoring or from the availability of toxico-dynamic predictive models to optimize linezolid dosing.

Complicated Case of Multidrug-Resistant Tuberculosis with Multiple Comorbidities, Successfully Treated After Several Treatment Modifications

A 59-year-old man with relapsed pulmonary TB developed rifampin resistance. He presented with chronic untreated hepatitis B, which developed into liver cirrhosis, type 2 diabetes with diabetic retinopathy, and osteoarthritis of right knee. His initial MDR regimen included levofloxacin, cycloserine, bedaquiline, linezolid, and high-dose isoniazid. He developed episodes of linezolid-induced myelosuppression, resulting in temporary discontinuation and dose reduction, and ultimately, substitution of linezolid. On the seventh month of treatment, he developed severe depression with visual hallucination, resulting in cycloserine dose reduction. We maintained the principle of at least 4 active drugs throughout his treatment. He was considered cured after 26 months of treatment.

Expert consensus statement on therapeutic drug monitoring and individualization of linezolid

Linezolid is an oxazolidinone antibacterial drug, and its therapeutic drug monitoring and individualized treatment have been challenged since its approval. With the in-depth clinical research of linezolid, we have changed our attitude toward its therapeutic drug monitoring and our view of individualized treatment. On the basis of summarizing the existing clinical studies, and based on the practical experience of each expert in their respective professional fields, we have formed this expert consensus. Our team of specialists is a multidisciplinary team that includes pharmacotherapists, clinical pharmacology specialists, critical care medicine specialists, respiratory specialists, infectious disease specialists, emergency medicine specialists and more. We are committed to the safe and effective use of linezolid in patients in need, and the promotion of its therapeutic drug monitoring.

Continuous Versus Intermittent Linezolid Infusion for Critically Ill Patients with Hospital-Acquired and Ventilator-Associated Pneumonia: Efficacy and Safety Challenges

High variability of linezolid blood concentrations with partial subtherapeutic levels was observed in critically ill patients who received a standard intravenous dose of linezolid, contributing to drug resistance and toxicity. Continuous infusions of linezolid have been suggested as an alternative and provide good serum and alveolar levels without fluctuations in trough concentration. This study aimed to assess the effectiveness and safety of continuous linezolid infusion versus the standard regimen in critically ill patients. A prospective randomized controlled study was conducted on 179 patients with nosocomial pneumonia. Patients were randomized into two groups. The first group received IV linezolid 600 mg twice daily, while the second group received 600 mg IV as a loading dose, followed by a continuous infusion of 1200 mg/day (50 mg/h) for at least 8−10 days. The continuous infusion group showed a higher clinical cure rate than the intermittent infusion group (p = 0.046). Furthermore, efficacy was proven by greater improvement of P/F ratio (p = 0.030) on day 7 of treatment, a lower incidence of developing sepsis after beginning treatment (p = 0.009), and a shorter time to reach clinical cure (p < 0.001). Hematological parameters were also assessed during the treatment to evaluate the safety between the two groups. The incidence of thrombocytopenia was significantly lower in the continuous infusion group than in the intermittent infusion group. In addition, a stepwise logistic regression model revealed that the intermittent infusion of linezolid was significantly associated with thrombocytopenia (OR =4.128; 95% CI = 1.681−10.139; p =0.001). The current study is the first to assess the clinical aspects of continuous infusion of linezolid beyond pharmacokinetic studies. Continuous infusion of linezolid outperforms intermittent delivery in safety and improves clinical effectiveness in critically ill patients with Gram-positive nosocomial pneumonia.

Risk factors for linezolid-induced thrombocytopenia in adult inpatients

Background Previous reports about risk factors for linezolid-induced thrombocytopenia have been insufficient, often due to the variability in study design and population, and some factors have not yet been studied. Aim The aims of this study are to determine potential risk factors for linezolid-induced thrombocytopenia, and to analyze the influencing factors of different thrombocytopenia definitions. Method This retrospective study involved patients who were administered intravenous linezolid for ≥ 1 day between January 1, 2015 and January 1, 2021. Their demographic and clinical data were extracted from electronic medical records. Thrombocytopenia was defined as: ①thrombocytopenia with platelet count < 100 × 10⁹/L and a decrease in 25% or more from baseline of the platelet count (criterion 1); ②thrombocytopenia due to a platelet count drop decrease of 25% or more from baseline (criterion 2). Risk factors were determined via binary logistic regression analysis. Results This study included 320 patients. Binary logistic regression analysis indicated that baseline platelet count (p < 0.001), linezolid therapy duration (p = 0.001) and shock (patients require vasoactive medications) (p = 0.019) were independent risk factors for criterion-1thrombocytopenia, while linezolid therapy duration (p < 0.001) and shock (p = 0.015) were independent risk factors for criterion-2 thrombocytopenia. There was also a significant correlation between shock and early-onset thrombocytopenia (p = 0.005 and 0.019 for criterion 1 and criterion 2, respectively). Conclusion Linezolid therapy duration and shock were common causes of different thrombocytopenia definitions; shock was correlated with early-onset thrombocytopenia. Platelet count should be monitored during linezolid therapy especially during long-duration therapy and in shock patients.

Effect of renal function on the risk of thrombocytopenia in patients receiving linezolid therapy: a systematic review and meta-analysis

Aims

The association of renal function and linezolid‐induced thrombocytopaenia (LIT) remains controversial. We performed a meta‐analysis to determine whether impaired renal function is associated with an increased LIT risk.

Methods

We conducted a systematic search of PubMed, EMBASE and the Cochrane Library from inception to February 2021 for eligible studies evaluating the relationship between renal function and LIT. Indicators of renal function included renal impairment (RI), severe RI, haemodialysis status, creatinine clearance rate (Ccr) and estimated glomerular filtration rate (eGFR). Unadjusted and adjusted estimates and 95% confidence intervals (CIs) were calculated separately using a random‐effect model.

Results

A total of 24 studies with 3580 patients were included in the meta‐analysis. RI patients had an increased LIT risk compared to non‐RI patients in both the unadjusted (OR 3.54; 95% CI 2.27, 5.54; I² = 77.7%) and adjusted analyses (OR 2.51; 95% CI 1.82, 3.45; I² = 17.9%). This association persisted in the subset of studies involving only patients receiving a fixed conventional dose (600 mg every 12 h) and other subgroup analyses by ethnicity, sample size and study quality. Moreover, the LIT risk was significantly higher in patients with severe RI and haemodialysis than in patients without severe RI and haemodialysis. The eGFR and Ccr were significantly lower in LIT patients than in non‐LIT patients.

Conclusions

Impaired renal function is associated with an increased risk of LIT. A reduced linezolid dose may be considered in RI patients at a low risk of treatment failure, ideally guided by therapeutic drug monitoring.

Clinical Use and Adverse Drug Reactions of Linezolid: A Retrospective Study in Four Belgian Hospital Centers

In Belgium, linezolid is indicated for pneumonia and skin and soft tissue infections, but is more broadly used, due to its oral bioavailability and activity against multiresistant organisms. This could increase the risk of adverse drug reactions (ADR), notably hematological disorders (anemia, thrombocytopenia), neuropathy, or lactic acidosis. We analyzed linezolid clinical use in relationship with occurrence of ADR in Belgian hospitals and highlighted risk factors associated with the development of thrombocytopenia. A retrospective analysis of electronic medical records and laboratory tests of adult patients treated with linezolid in four Belgian hospitals in 2016 allowed the collection of ADR for 248 linezolid treatments. Only 19.7% of indications were in-label. ADR included 43 thrombocytopenia, 17 anemia, 4 neuropathies, and 4 increases in lactatemia. In a multi-variate analysis, risk factors of thrombocytopenia were a treatment duration > 10 days, a glomerular filtration rate < 60 mL/min, and a Charlson index ≥ 4. Off-label use of linezolid is frequent in Belgium, and ADR more frequent than reported in the summary of product characteristics, but not statistically associated with any indication. This high prevalence of ADR could be related to a high proportion of patients presenting risk factors in our population, highlighting the importance of detecting them prospectively.

Classification Tree Analysis Based On Machine Learning for Predicting Linezolid-Induced Thrombocytopenia

Linezolid-induced thrombocytopenia is related to linezolid exposure, baseline platelet count and patient background. Although the relationship usually reflects the time of onset of thrombocytopenia, if the platelet maturation process is taken into account, the platelet decrease can be considered to have started at the beginning of treatment. To predict linezolid-induced thrombocytopenia, classification and regression tree (CART) analysis based on machine learning has been applied to identify predictive factors and cutoff values. We examined 74 patient data with or without linezolid-induced thrombocytopenia. Linezolid concentration and platelet count change, baseline platelet count, age, body weight and creatinine clearance estimate were evaluated as predictive factors for linezolid-induced thrombocytopenia. CART analysis selected the final tree containing two cutoff values: a platelet count reduction to less than 2.3% from baseline at 96 h after the initial dose and a linezolid concentration greater than or equal to 13.5 mg/L at 96 h after the initial dose. The targets for therapeutic intervention were concluded to be the linezolid concentration and the platelet change from baseline at 96 h after the initial dose. These cutoff values occur prior to the onset of thrombocytopenia and should be monitored to avoid linezolid-induced thrombocytopenia.

Analysis of the risk factors of linezolid-related haematological toxicity in Chinese patients

WHAT IS KNOWN AND OBJECTIVES

Haematological toxicity including thrombocytopenia, anaemia and leucopenia is the main adverse events of linezolid (LZD) therapy. This study aimed to investigate the risk factors for LZD-induced haematological toxicity and define the threshold of plasma trough concentration to minimize the haematological toxicity.

METHODS

145 patients who received LZD for more than 10 days were retrospectively reviewed to determine the incidence of LZD-induced haematological toxicity. Meanwhile, the risk factors of haematological toxicity were confirmed by univariate and multivariate logistic regression analysis.

RESULTS AND DISCUSSION

9 (6.2%) patients developed leucopenia, while 52 (35.9%) and 26 (17.9%) patients developed thrombocytopenia and anaemia, respectively. The estimated glomerular filtration rate (eGFR) <90 ml/min/1.73 m² (OR, 2.744; 95% CI, 1.117-6.734; p = 0.028) and baseline platelet count <200 × 10⁹ /L (OR, 6.817; 95% CI, 2.870-16.193; p < 0.0001) were found to be significant risk factors for LZD-related thrombocytopenia. Aspartate aminotransferase (AST) >80 U/L (OR, 4.844; 95% CI, 1.207-19.451; p = 0.026) and eGFR <90 ml/min/1.73 m² (OR, 7.132; 95% CI, 2.088-24.357; p = 0.002) were the risk factors for LZD-related anaemia. However, no significant risk factors were identified for LZD-related leucopenia. Moreover, LZD plasma trough concentration >8 mg/L [OR, 3.047; 95% CI, 1.233-7.539; p = 0.016] could be a predictor for the development of thrombocytopenia and anaemia.

WHAT IS NEW AND CONCLUSION

Hepatic and/or renal dysfunction are the risk factors for LZD-related haematological toxicity, while the target plasma trough concentration within 8 mg/L via dose reduction could minimize the haematological toxicity induced by LZD.

Proactive therapeutic drug monitoring (TDM) may be helpful in managing long-term treatment with linezolid safely: findings from a monocentric, prospective, open-label, interventional study

BACKGROUND

Thrombocytopenia may be a dose-dependent adverse effect of linezolid therapy.

OBJECTIVES

To assess whether proactive therapeutic drug monitoring (TDM) could be helpful in preventing and/or in recovering from the occurrence of linezolid-induced thrombocytopenia during long-term treatment.

METHODS

This was a monocentric, prospective, open-label, interventional study conducted between June 2015 and December 2017 among adult patients receiving >10 days of linezolid therapy and undergoing proactive TDM (desired trough level 2-8 mg/L) and platelet count assessment at day 3-5 and then once weekly up to the end of treatment.

RESULTS

Sixty-one patients were included. Twenty-eight (45.9%) always had desired trough level (group A) and 33 (54.1%) experienced linezolid overexposure (group B) [29/33 transiently (subgroup B1) and 4/33 persistently (subgroup B2)]. No patient experienced linezolid underexposure. Median duration of treatment for the different groups ranged between 19 and 54 days. Thrombocytopenia occurred overall in 14.8% of cases (9/61). The incidence rate of thrombocytopenia was significantly lower (P=0.012) in both group A (10.7%; 3/28) and subgroup B1 (10.3%; 3/29) than in subgroup B2 (75.0%; 3/4). Thrombocytopenic patients belonging to both group A and group B1 recovered from thrombocytopenia without the need for discontinuing therapy. Multivariate linear regression analysis revealed that thrombocytopenia was independently associated with baseline platelet count and with median linezolid trough concentrations.

CONCLUSIONS

Proactive TDM of linezolid may be beneficial either in preventing or in recovering from dose-dependent thrombocytopenia, even when treatment lasts for more than 28 days. Larger prospective studies are warranted to confirm our findings.

Linezolid Dosing in Patients With Liver Cirrhosis: Standard Dosing Risk Toxicity

BACKGROUND

Limited data regarding altered linezolid pharmacokinetics in patients with liver cirrhosis are available. The objective of this study was to evaluate the pharmacokinetics, efficacy and safety of linezolid in cirrhotic patients.

METHODS

A case-control 1:1 study of patients undergoing linezolid therapeutic drug monitoring was conducted between January 2015 and June 2017. Cases with liver cirrhosis were matched with controls by age, body weight, comorbidities, renal function, and intensive care unit (ICU) admission.

RESULTS

Fifty-two patients were included, 26 in each group. Patients with Child-Pugh Scores A, B, and C were 1 (3.8%), 13 (50.0%), and 12 (46.2%), respectively. Cases had higher median linezolid trough plasma concentrations than controls [20.6 (17.4) versus 2.7 (11.3); P < 0.001)] and more frequently achieved an optimal pharmacodynamic index [26 (100%) versus 16 (61.5%); P = 0.002]. In addition, potentially toxic concentrations and treatment discontinuation due to overexposure and hematological toxicity were also more frequently seen in cirrhotic patients. Overall clinical cure rate was high (67.4%), and in-hospital mortality was 28.8%. No differences in clinical outcomes were observed between both groups.

CONCLUSIONS

Linezolid showed a high clinical cure rate. Nevertheless, plasma concentrations and treatment discontinuation due to hematological toxicity were higher in cirrhotic patients. Liver cirrhosis may influence linezolid pharmacokinetics and question the use of standard doses. Therapeutic drug monitoring of linezolid would be valuable in these patients.

Impact of high plasma concentrations of linezolid in Taiwanese adult patients- therapeutic drug monitoring in improving adverse drug reactions

BACKGROUND

Previous studies have shown that the development of thrombocytopenia was associated with the elevated plasma concentration of linezolid, but little is known about the relationship between other uncommon adverse drug reactions (ADRs) and plasma concentration. The appropriate dosing adjustment has remained controversial. This prospective observational study was conducted to investigate the association between the plasma concentration of linezolid, ADRs, and clinical outcomes.

METHODS

Adult patients on linezolid treatment undergoing at least one therapeutic drug monitoring (TDM) were enrolled. The association between linezolid concentrations and ADRs was examined by multivariate Cox regression model. Predictors of linezolid concentrations was determined by linear regression model. The cut-off point of linezolid concentration and the effect of dosing adjustments based on TDM was also explored.

RESULTS

Of 50 patients enrolled in the study, plasma concentrations were 1.5-3 times higher than what was described in the prescribing information. The median minimum concentration (C_min) was significantly higher in patients with thrombocytopenia compared to patients without thrombocytopenia (13.0 vs. 7.2 μg/mL, P = 0.0273), and a higher median maximum concentration was also observed in patients with lactic acidosis (33.0 vs. 27.5 μg/mL, P = 0.0420). The C_min was elevated in patients with advanced age and severely impaired renal function. Dosing adjustment tailored by early TDM with the upper limit of C_min 9 μg/mL may improve platelet counts.

CONCLUSION

Elevated linezolid concentrations were associated with thrombocytopenia and lactic acidosis. TDM-guided dosing adjustment could be considered as a pragmatic way to mitigate thrombocytopenia.

Risk factor analysis for linezolid-associated thrombocytopenia in critically ill patients

Linezolid is an antibiotic used against gram-positive bacteria, including methicillin-resistant Staphylococcus aureus. Its primary adverse effect is haematotoxicity. The objective of this study was to analyse the risk factors for onset of thrombocytopenia in critically ill patients treated with linezolid. This was a retrospective, single-centre study of 72 patients. Platelets were measured from D0 to D20 after the start of treatment. The risk factors for thrombocytopenia were identified using a multivariate logistic regression analysis following a Monte Carlo simulation. Following ROC curve analysis, a baseline platelet count lower than 108 × 10⁹/L and a C_min higher than 4 mg/L, with respective odds ratios of 117 (95% CI [97-206]) and 3 (95% CI [1.5-6.2]) in the simulated population, were identified as risk factors. Among the source population patients combining these 2 factors, a significantly higher number developed thrombocytopenia (66.7% vs. 33.3%, p = 0.0042). A baseline platelet count lower than 108 × 10⁹/L and a C_min higher than 4 mg/L are risk factors for the onset of thrombocytopenia in critically ill patients treated with linezolid.

Reversible recurrent profound thrombocytopenia due to linezolid in a patient with multi-drug resistant tuberculosis: A case report

RATIONALE

Thrombocytopenia caused by linezolid (LZD) is common, with a reported prevalence as high as 11.8%. Platelets typically reach normal levels 7 days after LZD withdrawal. However, recurrent profound thrombocytopenia due to LZD usage and a persistent profound drop in platelet count after LZD withdrawal have not been reported.

PATIENT CONCERNS

We report a case of a 75-year-old woman, who presented with recurrent profound thrombocytopenia induced by LZD treatment for multidrug-resistant tuberculosis (MDR-TB).

DIAGNOSES

Laboratory data and symptoms during and after LZD usage and reusage indicated severe thrombocytopenia.

INTERVENTIONS

LZD was discontinued due to recurrent thrombocytopenia and the platelet count continued to drop for 9 days and returned to normal gradually 16 days after LZD withdrawal and supportive care including platelet transfusion.

OUTCOMES

There was no recurrence of thrombocytopenia during 10 months of follow-up during treatment for MDR-TB with a regimen without LZD.

LESSONS

Recurrent profound thrombocytopenia can happen after several doses of LZD rechallenging. Therefore, reuse of LZD should be avoided after recovery from severe thrombocytopenia due to LZD.

Weight-based dosing in medication use: what should we know?

BACKGROUND

Weight-based dosing strategy is still challenging due to poor awareness and adherence. It is necessary to let clinicians know of the latest developments in this respect and the correct circumstances in which weight-based dosing is of clinical relevance.

METHODS

A literature search was conducted using PubMed.

RESULTS

Clinical indications, physiological factors, and types of medication may determine the applicability of weight-based dosing. In some cases, the weight effect may be minimal or the proper dosage can only be determined when weight is combined with other factors. Medications within similar therapeutic or structural class (eg, anticoagulants, antitumor necrosis factor medications, P2Y12-receptor antagonists, and anti-epidermal growth factor receptor antibodies) may exhibit differences in requirements on weight-based dosing. In some cases, weight-based dosing is superior to currently recommended fixed-dose regimen in adult patients (eg, hydrocortisone, vancomycin, linezolid, and aprotinin). On the contrary, fixed dosing is noninferior to or even better than currently recommended weight-based regimen in adult patients in some cases (eg, cyclosporine microemulsion, recombinant activated Factor VII, and epoetin α). Ideal body-weight-based dosing may be superior to the currently recommended total body-weight-based regimen (eg, atracurium and rocuronium). For dosing in pediatrics, whether weight-based dosing is better than body surface-area-based dosing is dependent on the particular medication (eg, methotrexate, prednisone, prednisolone, zidovudine, didanosine, growth hormone, and 13-cis-retinoic acid). Age-based dosing strategy is better than weight-based dosing in some cases (eg, intravenous busulfan and dalteparin). Dosing guided by pharmacogenetic testing did not show pharmacoeconomic advantage over weight-adjusted dosing of 6-mercaptopurine. The common viewpoint (ie, pediatric patients should be dosed on the basis of body weight) is not always correct. Effective weight-based dosing interventions include standardization of weight estimation, documentation and dosing determination, dosing chart, dosing protocol, order set, pharmacist participation, technological information, and educational measures.

CONCLUSION

Although dosing methods are specified in prescribing information for each drug and there are no principal pros and cons to be elaborated, this review of weight-based dosing strategy will enrich the knowledge of medication administration from the perspectives of safety, efficacy, and pharmacoeconomics, and will also provide research opportunities in clinical practice. Clinicians should be familiar with dosage and administration of the medication to be prescribed as well as the latest developments.

Risk factors for linezolid-associated thrombocytopenia in adult patients

Objectives

Thrombocytopenia (TP) is a common adverse effect of linezolid (LZD). However, risk factors for LZD-associated TP have been reported in Western patients with relatively heavy body weight. The aim of this study was to determine the risk factors for LZD-associated TP in Asian population.

Materials and methods

A retrospective cohort study was conducted among 101 consecutive patients who received LZD therapy (1,200 mg/day) between July 2003 and December 2013 at a tertiary referral hospital in Tokyo, Japan. The patients with obvious other causes for TP were excluded. The information of target infectious disease, patients’ age, gender, body weight, body mass index, baseline serum creatinine (SCr), baseline platelet count, and treatment duration was collected retrospectively. TP was defined as ≥50 % decrease in platelet count from baseline. Bi- and multi-variate analyses were performed.

Results

A total of 101 patients were included (mean age [SD] 64 [18]; male gender [%], 57 [56]). Median duration [range] of LZD therapy was 14 days [1–67]. LZD-associated TP was identified in 42 patients (42 %). For TP, adjusted odds ratio (OR) [95 % CI] of daily per kg dose (DPKD) and SCr was 1.14 [1.05–1.26] and 1.51 [1.01–2.50], respectively.

Conclusions

Higher DPKD and elevated SCr are significantly associated with LZD-associated TP. These findings suggest that daily dose of LZD should be adjusted using body weight, as typically done in pediatrics, in adults as well. Renal function also should be considered for dose adjustment.