Major adverse cardiovascular events associated with testosterone treatment: a pharmacovigilance study of the FAERS database.

Background and purpose: Testosterone is an essential sex hormone in maintaining masculine characteristics, which is prescribed for male hypogonadism as testosterone replacement treatment (TRT). Herein, we investigated long-standing controversies about the association between TRT and major adverse cardiovascular events (MACEs), based on real world adverse event (AE) reports, registered in the Food and Drug Administration Adverse Event Reporting System (FAERS). Methods: Publicly available FAERS data from 1 January 2004 to 31 December 2022 were retrieved from the Food and Drug Administration (FDA) website. The data mining protocol including the reporting odds ratio (ROR) and the Bayesian confidence propagation neural network (BCPNN) was applied to analyze overreporting caused by risk factors and MACEs, including TRT, morbidities, and ages. The ROR and the BCPNN were also applied to investigate the annually developing trend of pharmacovigilance (PV) signals in the real world, retrospectively. Results: A total of 3,057 cases referring to MACEs, with a median age of 57 years old (yo), were identified from 28,921 cases of testosterone users. MACEs related to PV signals have emerged since 2014, including cardiac death, non-fatal myocardial infarction, and non-fatal stroke. Myocardial infarction (MI) (ROR: 9.46; IC025: 3.08), acute myocardial infarction (AMI) (ROR: 16.20; IC025: 3.72), ischemic cardiomyopathy (ROR: 11.63; IC025: 2.20), and cardiomyopathy (ROR: 5.98; IC025: 1.96) were the most significant signals generated, and weaker signals included cardiac failure acute (ROR: 4.01; IC025: 0.71), cardiac arrest (ROR: 1.88; IC025: 0.56), and ventricular fibrillation (VF) (ROR: 2.38; IC025: 0.38). The time-to-onset (TTO) of MACEs was calculated with a median of 246 days for AMI. Conclusion: For myocardial infarction and cardiomyopathy, TRT statistically tended to increase the risk of MACEs, while for cardiac arrhythmia, cardiac failure, and stroke, TRT demonstrated beneficial effects among the population with morbidities, such as testosterone deficiency (TD), diabetes mellitus (DM), and hypertension. MACEs were rare but led to serious outcomes including significant increase in death and disability. Since 2018, and before 2014, reports referring to TRT associated with MACEs were relatively scarce, which indicated that there might be a considerable number of cases that went unrecorded, due to neglection. Health workers and testosterone users might pay more attention to testosterone-induced MACEs.

Sodium-glucose co-transporter-2 inhibitor (SGLT2i) treatment and risk of osteomyelitis: A pharmacovigilance study of the FAERS database.

Background and purpose: Several clinical trials have indicated that the use of canagliflozin increases the risk of lower extremity amputation. Although the US Food and Drug Administration (FDA) has withdrawn its black box warning about amputation risk for canagliflozin, the risk still exists. We sought to estimate the association between hypoglycemic medications, especially sodium-glucose co-transporter-2 inhibitors (SGLT2is), and adverse events (AEs) before the irreversible outcome of amputation as a promising early warning, based on the FDA Adverse Event Reporting System (FAERS) data. Methods: Publicly available FAERS data were analyzed using a reporting odds ratio (ROR) method and validated by a Bayesian confidence propagation neural network (BCPNN) method. The developing trend of the ROR was investigated by a series of calculations based on the accumulation of data in the FAERS database quarter by quarter. Results: Ketoacidosis, infection, peripheral ischemia, renal impairment, and inflammation including osteomyelitis might be more likely to occur among users of SGLT2is, especially canagliflozin. Osteomyelitis and cellulitis are AEs unique to canagliflozin. Among 2,888 osteomyelitis-related reports referring to hypoglycemic medications, 2,333 cases were associated with SGLT2is, with canagliflozin accounting for 2,283 of these cases and generating an ROR value of 360.89 and a lower limit of information component (IC025) of 7.79. No BCPNN-positive signal could be generated for drugs other than insulin and canagliflozin. Reports suggesting that insulin could generate BCPNN-positive signals span from 2004 to 2021, whereas reports with BCPNN-positive signals emerged only since the second quarter (Q2) of 2017, 4 years since the approval of SGLT2is in Q2 of 2013, for canagliflozin and drug groups containing canagliflozin. Conclusion: This data-mining investigation revealed a strong association between canagliflozin treatment and developing osteomyelitis that might be a crucial forewarning to lower extremity amputation. Further studies with updated data are needed to better characterize the risk of osteomyelitis associated with SGLT2is.

Individual dose recommendations for drug interaction between tacrolimus and voriconazole in adult liver transplant recipients: A semiphysiologically based population pharmacokinetic modeling approach.

The magnitude of drug-drug interaction between tacrolimus and voriconazole is highly variable, and individually tailoring the tacrolimus dose when concomitantly administered with voriconazole remains difficult. This study aimed to develop a semiphysiologically based population pharmacokinetic (semi-PBPK) model and a web-based dashboard to identify the dynamic inhibition of tacrolimus metabolism caused by voriconazole and provide individual tacrolimus regimens for Chinese adult liver transplant recipients. A total of 264 tacrolimus concentrations and 146 voriconazole concentrations were prospectively collected from 32 transplant recipients. A semi-PBPK model with physiological compartments including the gut wall, portal vein, and liver was developed using the nonlinear mixed-effects modeling software NONMEM (version 7.4). A web-based dashboard was established in R software (version 3.6.1) to recommend the individual tacrolimus regimens when concomitantly administered with voriconazole. The reversible inhibition of tacrolimus metabolism caused by voriconazole was investigated in both the liver and the gut wall. Moreover, voriconazole could highly inhibit the CYP3A activity in the gut wall more than in the liver. BMI and postoperative days were identified as significant covariates on intrinsic intestinal and hepatic clearance of tacrolimus, respectively. Age and postoperative days were identified as significant covariates on the volume of distribution of voriconazole. The individual tacrolimus regimens when concomitantly administered with voriconazole could be recommended in the dashboard (https://tac-vor-ddi.shinyapps.io/shinyapp3/). In conclusion, the semi-PBPK model successfully described the dynamic inhibition process between tacrolimus and voriconazole, and the web-based dashboard could provide individual tacrolimus regimens when concomitantly administered with voriconazole.

Is a Lower Dose of Rivaroxaban Required for Asians? A Systematic Review of a Population Pharmacokinetics and Pharmacodynamics Analysis of Rivaroxaban.

Rivaroxaban has been widely used to prevent and treat various thromboembolic diseases for more than a decade. However, whether a lower dose of rivaroxaban is required for Asians is still debatable. This review aimed to explore the potential ethnic difference in pharmacokinetic/pharmacodynamic (PK/PD) characteristics between Asians and Caucasians. A systematic search was conducted and twenty-four studies were identified, of which 10 were conducted on Asian adults, 11 on predominantly Caucasian adults, and 3 on Caucasian pediatrics. The apparent clearance (CL/F) of rivaroxaban in Caucasian adults with non-valvular atrial fibrillation (6.45-7.64 L/h) was about 31-43% higher than that in Asians (4.46-5.98 L/h) taking 10~20 mg rivaroxaban every 24 h. Moreover, there was no obvious difference in CL/F among Japanese, Chinese, Thai, and Irani people. Regarding PK/PD relationship, prothrombin time was linked to rivaroxaban concentration in a linear or near-linear manner, and Factor Xa activity was linked with the Emax model. The exposure-response relationship was comparable between Asians and Caucasians. Renal function has a significant influence on CL/F, and no covariate was recognized for exposure-response relationship. In conclusion, a lower dose of rivaroxaban might be required for Asians, and further studies are warranted to verify this ethnic difference to facilitate optimal dosing regimens.

Skin cancer signal associated with phosphodiesterase inhibitors: gaining insight through the FDA pharmacovigilance database.

BACKGROUND: Panoramic views of post-marketing safety profiles, such as cancer signal, of phosphodiesterase 5A (PDE5A) inhibitors have yet to be fully evaluated. RESEARCH DESIGN AND METHODS: Data from the FDA Adverse Event Reporting System (FAERS) concerning the timeframe between January 1st, 2004 to 30 June 2022 was analyzed through a disproportionality study to understand the association between sildenafil, tadalafil, and vardenafil and cancer. This association was identified using the Reporting odds ratio (ROR) and Bayesian Confidence Propagation Neural Network (BCPNN) approaches. RESULTS: Sildenafil associated ROR values and IC025 ranged from 9.19 (95% CI 7.72-10.94, IC025 2.77) for metastatic malignant melanoma to 132.23 (95% CI 95.49-183.11, IC025 4.69) for malignant melanoma stage II. Tadalafil associated ROR and IC025 ranged from 6.79 (95% CI 5.41-8.54, IC025 2.27) for metastatic malignant melanoma to 180.17 (95% CI 130.11-249.50, IC025 4.89) for malignant melanoma stage II. Vardenafil associated ROR and IC025 ranged from 23.38 (95% CI 15.20-35.96, IC025 2.63) for metastatic malignant melanoma to 245.77 (95% CI 154.42-391.16, IC025 2.10) for malignant melanoma stage III. CONCLUSIONS: This study supports the association between sildenafil, tadalafil, and vardenafil with skin cancer signal in erectile dysfunction (ED) patients.

Handling Delayed or Missed Dose of Antiseizure Medications: A Model-Informed Individual Remedial Dosing.

BACKGROUND AND OBJECTIVES: Delayed or missed antiseizure medications (ASMs) doses are common during long-term or lifelong antiepilepsy treatment. This study aims to explore optimal individualized remedial dosing regimens for delayed or missed doses of 11 commonly used ASMs. METHODS: To explore remedial dosing regimens, Monte Carlo simulation was used based on previously identified and published population pharmacokinetic models. Six remedial strategies for delayed or missed doses were investigated. The deviation time outside the individual therapeutic range was used to evaluate each remedial regimen. The influences of patients' demographics, concomitant medication, and scheduled dosing intervals on remedial regimens were assessed. RxODE and Shiny in R were used to perform Monte Carlo simulation and recommend individual remedial regimens. RESULTS: The recommended remedial regimens were highly correlated with delayed time, scheduled dosing interval, and half-life of the ASM. Moreover, the optimal remedial regimens for pediatric and adult patients were different. The renal function, along with concomitant medication that affects the clearance of the ASM, may also influence the remedial regimens. A web-based dashboard was developed to provide individualized remedial regimens for the delayed or missed dose, and a user-defined module with all parameters that could be defined flexibly by the user was also built. DISCUSSION: Monte Carlo simulation based on population pharmacokinetic models may provide a rational approach to propose remedial regimens for delayed or missed doses of ASMs in pediatric and adult patients with epilepsy.

How to handle a delayed or missed dose of edoxaban in patients with non-valvular atrial fibrillation? A model-informed remedial strategy.

AIMS: Edoxaban is a non-vitamin K antagonist oral anticoagulant (NOAC) widely used for the long-term prevention of stroke in patients with non-valvular atrial fibrillation (NVAF). Adherence to NOAC therapy has been unsatisfactory and decreases over time. Remedial strategies are currently used to address the non-adherence events. Current recommendations, however, are generic and not well supported by evidence. The aim of this study was to explore appropriate remedial dosing regimens for non-adherent edoxaban-treated NVAF patients through Monte Carlo simulation. METHODS: Six regimens were compared with the current recommendations of the European Heart Rhythm Association (EHRA) guide based on total deviation time. Both edoxaban plasma concentration and intrinsic Factor Xa activity were considered. Monte Carlo simulations were performed using RxODE based on a published population pharmacokinetic/pharmacodynamic (PK/PD) model. RESULTS: The proposed remedial strategies were different than the EHRA recommendations and were related to the delay time. However, it was found that the missed dose can be administered immediately if the delay time is within 11 h. When the delay is between 12 and 19 h, a half dose followed by a regular dosing schedule is recommended. When the delay time exceeds 19 h, a full dose followed by a half dose is preferred. CONCLUSION: PK/PD modelling and simulation are effective in developing and evaluating the remedial strategies of edoxaban, which can help maximise its therapeutic effect.

Population Pharmacokinetic Modeling Combined With Machine Learning Approach Improved Tacrolimus Trough Concentration Prediction in Chinese Adult Liver Transplant Recipients.

This study aimed to develop and evaluate a population pharmacokinetic (PPK) combined machine learning approach to predict tacrolimus trough concentrations for Chinese adult liver transplant recipients in the early posttransplant period. Tacrolimus trough concentrations were retrospectively collected from routine monitoring records of liver transplant recipients and divided into the training data set (1287 concentrations in 145 recipients) and the test data set (296 concentrations in 36 recipients). A PPK model was first established using NONMEM. Then a machine learning model of Xgboost was adapted to fit the estimated individual pharmacokinetic parameters obtained from the PPK model with Bayesian forecasting. The performance of the final PPK model and Xgboost model was compared in the test data set. In the final PPK model, tacrolimus daily dose, postoperative days, hematocrit, aspartate aminotransferase, and concomitant voriconazole, were identified to significantly influence the clearance. The postoperative days along with hematocrit significantly influence the volume of distribution. In the Xgboost model, the first 5 predictors for predicting the clearance were concomitant with voriconazole, sex, single nucleotide polymorphisms of CYP3A4*1G and CYP3A5*3 in recipients, and tacrolimus daily dose, for the volume of distribution were postoperative days, age, weight, total bilirubin and graft : recipient weight ratio. In the test data set, the Xgboost model showed the minimum median prediction error of tacrolimus concentrations, less than the PPK model with or without Bayesian forecasting. In conclusion, a PPK combined machine learning approach could improve the prediction of tacrolimus concentrations for Chinese adult liver transplant recipients in the early posttransplant period.

Serious adverse reaction associated with the COVID-19 vaccines of BNT162b2, Ad26.COV2.S, and mRNA-1273: Gaining insight through the VAERS.

Background and purpose: Serious adverse events following immunization (AEFI) associated with the COVID-19 vaccines, including BNT162b2 (Pfizer-BioNTech), Ad26.COV2.S (Janssen), and mRNA-1273 (Moderna), have not yet been fully investigated. This study was designed to evaluate the serious AEFI associated with these three vaccines. Methods: A disproportionality study was performed to analyze data acquired from the Vaccine Adverse Event-Reporting System (VAERS) between 1 January 2010 and 30 April 2021. The reporting odds ratio (ROR) method was used to identify the association between the COVID-19 vaccines BNT162b2, Ad26.COV2.S, and mRNA-1273 and each adverse event reported. Moreover, the ratio of the ROR value to the 95% CI span was applied to improve the credibility of the ROR. The median values of time from vaccination to onset (TTO) for the three vaccines were analyzed. Results: Compared with BNT162b2 and mRNA-1273, Ad26.COV2.S vaccination was associated with a lower death frequency (p < 0.05). Ad26.COV2.S vaccination was associated with a lower birth defect and emergency room visit frequency than BNT162b2 (p < 0.05). There were 6,605, 830, and 2,292 vaccine recipients who suffered from COVID-19-related symptoms after vaccination with BNT162b2, Ad26.COV2.S, and mRNA-1273, respectively, including people who were infected by COVID-19, demonstrated a positive SARS-CoV-2 test, and were asymptomatic. Serious AEFI, including thromboembolism, hemorrhage, thrombocytopenia, cardiac arrhythmia, hypertension, and hepatotoxicity, were associated with all three vaccines. Cardiac failure and acute renal impairment events were associated with BNT162b2 and mRNA-1273, while seizure events were associated with BNT162b2 and Ad26.COV2.S. The median values of TTO associated with the three vaccinations were similar. Conclusion: These findings may be useful for health workers and the general public prior to inoculation, especially for patients with underlying diseases; however, the risk/benefit profile of these vaccines remains unchanged. The exact mechanism of SARS-CoV-2 vaccine-induced AEFI remains unknown, and further studies are required to explore these phenomena.

Association between cyclin-dependent kinase 4/6 inhibitors and venous thromboembolism: analysis of F.A.E.R.S. data.

OBJECTIVES: Real world studies have started to emerged on occurrence of venous thromboembolism (VTE) with cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors, but still deserve constant surveillance and evaluation. This study was to analyze this association. METHODS: Adverse event cases were acquired from the US Food and Drug Administration Adverse Event Reporting System (FAERS) database betweenJanuary 1st 2015 and December 31st 2020.Signals indicating association between CDK 4/6 inhibitors and VTE were identified by reporting odds ratio (ROR). RESULTS:  CDK 4/6 inhibitors had a total of 631 reports of VTE (ROR 1.44, 95% CI 1.33-1.55) compared with non-CDK 4/6 inhibitors. Palbociclib (ROR 1.42, 95% CI 1.09-1.88) demonstratedthe highest number of VTE reports, followed by ribociclib (ROR 1.41, 95% CI 1.29-1.54) and abemaciclib (ROR 0.92, 95% CI 0.72-1.17). CONCLUSIONS: Although it is not able to confirm the casual relationship between VTE and CDK4/6 inhibitors, this study suggested signal of VTE reporting in patients receiving CDK4/6 inhibitors, which is likely to reflect a potential association. The results may enhance physicians' awareness of the potential side effect of VTE associated with CDK 4/6 inhibitors. An early recognition of VTE signs/symptoms could decrease the morbidity and severity of such adverse events.

Effect of albumin and CYP2B6 polymorphisms on exposure of efavirenz: A population pharmacokinetic analysis in Chinese HIV-infected adults.

BACKGROUND: Efavirenz is a vital component used to treat HIV-1 infection. Nevertheless, it shows large between-subject variability, which affects both its therapeutic response and adverse effects. OBJECTIVE: To investigate the impact of gene polymorphisms and non-genetic factors on the variability of efavirenz pharmacokinetics and to propose the optimal dose regimens. METHODS: A total of 769 plasma samples from 376 HIV-infected Han Chinese outpatients were collected to develop a population pharmacokinetic model using NONMEM software. The impact of patient demographics, laboratory tests, concomitant medication, and genetic polymorphisms of CYP2B6 and ABCB1 on efavirenz pharmacokinetics were explored. According to the final model, the model-informed dose optimization was conducted. RESULTS: The pharmacokinetics of efavirenz was characterized by a one-compartment model with first-order absorption and elimination. The typical values of the estimated apparent oral clearance, volume of distribution, and absorption rate constant in the final model were 9.44 L/h, 200 L, and 0.727 h - 1, respectively. Efavirenz clearance was significantly influenced by CYP2B6 variants, including rs2099361, rs3745274, and rs2279343, along with albumin and weight. The volume of distribution was affected by albumin and weight. Based on the CYP2B6 polymorphisms of patients, the recommended daily doses of efavirenz were 100 mg for CYP2B6 slow metabolizers, 400 or 600 mg for intermediate metabolizers, and 800 or 1000 mg for extensive metabolizers. CONCLUSIONS: Polymorphisms of CYP2B6, along with albumin and weight, resulted as the predictors of efavirenz pharmacokinetic variability, which could be used in prescribing optimal efavirenz doses.

How to handle the delayed or missed dose of rivaroxaban in patients with non-valvular atrial fibrillation: model-informed remedial dosing.

BACKGROUND: Rivaroxaban is an oral anticoagulant widely used for stroke prevention in patients with non-valvular atrial fibrillation (NVAF). During long-term anticoagulant therapy, delayed or missed doses are common. This study aimed to explore appropriate remedial dosing regimens for non-adherent rivaroxaban-treated patients. METHODS: Monte Carlo simulation based on a previously established rivaroxaban population pharmacokinetic/pharmacodynamic (PK/PD) model for patients with NVAF was employed to design remedial dosing regimens. The proposed regimens were compared with remedial strategies in the European Heart Rhythm Association (EHRA) guide by assessing deviation time in terms of drug concentration, factor Xa activity, and prothrombin time. RESULTS: The proposed remedial dosing regimens were dependent on delay duration. The missed dose should be taken immediately when the delay does not exceed 6 h; a half dose is advisable when the delay is between 6 and 20 h. A missed dose should be skipped if less than 4 h remains before the next dose. The proposed regimens resulted in shorter deviation time than that of the EHRA guide. CONCLUSION: PK/PD modeling and simulation provide valid evidence on the remedial dosing regimen of rivaroxaban, which could help to minimize the risk of bleeding and thromboembolism.

Population Pharmacokinetics of Ropeginterferon Alfa-2b: A Comparison Between Healthy Caucasian and Chinese Subjects.

Objective: To develop a population pharmacokinetic (PK) model for ropeginterferon alfa-2b and to compare its PK properties between Caucasian and Chinese populations. Methods: A population PK model was developed based on data from two phase I clinical trials conducted in Caucasian and Chinese individuals, to evaluate the influence of ethnicity on the PKs of ropeginterferon alfa-2b. Results: We included 456 observations from 30 healthy Caucasian subjects and 438 observations from 27 healthy Chinese subjects in the population PK analysis. The PKs of ropeginterferon alfa-2b were best described by a one-compartment quasi-equilibrium approximated target-mediated drug disposition model with first-order absorption and absorption lag times. The typical value (relative standard error%) of apparent clearance (CL/F) and volume of distribution of ropeginterferon alfa-2b in 70-kg subjects were 0.778 (12%) L/day and 2.32 (14%) L, respectively. Body weight was the only significant factor affecting the CL/F. There were no obvious differences in the PK properties of ropeginterferon alfa-2b, and predicted steady-state exposure was similar in the Chinese and Caucasian populations. Conclusion: No significant ethnic differences in ropeginterferon alfa-2b PKs were observed between the Chinese and Caucasian populations.

Population pharmacokinetics of oxcarbazepine: a systematic review.

INTRODUCTION: Oxcarbazepine is commonly used as first-line treatment for partial and generalized tonic-clonic seizures. Owing to the high pharmacokinetic variability, several population pharmacokinetic models have been developed for oxcarbazepine to explore potential covariates that affect its pharmacokinetic variation. AREAS COVERED: This review summarizes the published population pharmacokinetic studies of oxcarbazepine in children and adults available in PubMed and Embase databases. The quality of the retrieved studies was evaluated, and significant covariates that may have an impact on the dosage regimen of oxcarbazepine were explored. EXPERT OPINION: The pharmacokinetics of oxcarbazepine was founded to be affected by body weight and co-administration with enzyme inducers. Pediatric patients require a higher dose per kilogram than adults because children generally have a higher clearance than adults. Moreover, to maintain the target concentration, patients co-administrate with enzyme inducers need a higher dose than monotherapy due to higher clearance in those patients. Because limited information is available for exposure-response relationship, additional pharmacokinetic/pharmacodynamics investigations of oxcarbazepine need to be conducted to optimize the dosage regimen in clinical practice.

Population Pharmacokinetics of Levetiracetam: A Systematic Review.

BACKGROUND: Levetiracetam has been widely used as a treatment option for different types of epilepsy in both adults and children. Because of its large between-subject variability, several population pharmacokinetic studies have been performed to identify its pharmacokinetic covariates, and thus facilitate individualised therapy. OBJECTIVE: The aim of this review was to provide a synopsis for population pharmacokinetic studies of levetiracetam and explore the identified influencing covariates. METHODS: We systematically searched the PubMed and Embase databases from inception to 30 June 2020. The information on study designs, target population, model characteristics, and identified covariates was summarised. Moreover, the pharmacokinetic profiles were compared among neonates, children, and adults. RESULTS: Fourteen studies were included, among which two involved neonates, four involved children, two involved both children and adults, and six involved adults only. The median value of apparent clearance for children (0.074 L/h/kg [range 0.038-0.079]) was higher than that for adults (0.054 L/h/kg [range 0.039-0.061]). Body weight was found to significantly influence the apparent clearance and volume of distribution, whereas renal function influenced the clearance. Likewise, coadministration with enzyme-inducing antiepileptic drugs (such as carbamazepine and phenytoin) increased the drug clearance by 9-22%, whereas coadministration with valproate acid decreased it by 18.8%. CONCLUSION: Levetiracetam dose regimen is dependent on the body size and renal function of patients. Further studies are needed to evaluate levetiracetam pharmacokinetics in neonates and pregnant women.

Can Population Pharmacokinetics of Antibiotics be Extrapolated? Implications of External Evaluations.

BACKGROUND AND OBJECTIVE: External evaluation is an important issue in the population pharmacokinetic analysis of antibiotics. The purpose of this review was to summarize the current approaches and status of external evaluations and discuss the implications of external evaluation results for the future individualization of dosing regimens. METHODS: We systematically searched the PubMed and EMBASE databases for external evaluation studies of population analysis and extracted the relevant information from these articles. A total of 32 studies were included in this review. RESULTS: Vancomycin was investigated in 17 (53.1%) articles and was the most studied drug. Other studied drugs included gentamicin, tobramycin, amikacin, amoxicillin, ceftaroline, meropenem, fluconazole, voriconazole, and rifampicin. Nine (28.1%) studies were prospective, and the sample size varied widely between studies. Thirteen (40.6%) studies evaluated the population pharmacokinetic models by systematically searching for previous studies. Seven (21.9%) studies were multicenter studies, and 27 (84.4%) adopted the sparse sampling strategy. Almost all external evaluation studies of antibiotics (93.8%) used metrics for prediction-based diagnostics, while relatively fewer studies were based on simulations (46.9%) and Bayesian forecasting (25.0%). CONCLUSION: The results of external evaluations in previous studies revealed the poor extrapolation performance of existing models of prediction- and simulation-based diagnostics, whereas the posterior Bayesian method could improve predictive performance. There is an urgent need for the development of standards and guidelines for external evaluation studies.

Population Pharmacokinetic Analysis of Tacrolimus in Adult Chinese Patients with Myasthenia Gravis: A Prospective Study.

BACKGROUND AND OBJECTIVES: Tacrolimus is a widely used immunosuppressive agent with narrow therapeutic window. Nowadays, tacrolimus has gained acceptance as a therapeutic option in myasthenia gravis (MG) treament, however, little is known about its pharmacokinetic characteristics in MG population. In this study, we aimed to investigate the population pharmacokinetic (PopPK) of tacrolimus in patients with MG and to develop model-informed dosing regimens. METHODS: Trough concentrations of tacrolimus (267 measurements) and cytochrome P450 (CYP) genotypes were determined in 97 Chinese adults. The non-linear mixed-effects model was used for PopPK modeling. Monte Carlo simulations based on the established model were employed to design dosing regimens. RESULTS: The PopPK model was described using a one-compartment model with first-order absorption and elimination. The mean apparent clearance (CL/F) of tacrolimus was 17.1 L/h, with a between-subject variability of 20.1%. Covariate screening of demographic characteristics, blood test results, co-medications, and CYP3A5*3 or CYP3A4*1G polymorphisms showed that the CYP3A5*3 genotype and co-administration of a Wuzhi capsule significantly affected tacrolimus CL/F. CONCLUSIONS: For patients with the CYP3A5*3*3 allele, the required tacrolimus dose for 75% of subjects to achieve target trough concentrations of 4.8-15 ng/mL was 2 mg every 12 h (q12h). For patients with the CYP3A5*1*1 allele, the required dose was 2 mg tacrolimus q12h with a Wuzhi capsule, and for patients with the CYP3A5*1*3 allele, the required dose was 3 mg of tacrolimus q12h or 4 mg q24h co-administered with a Wuzhi capsule. This model could be employed to optimize individualized therapies for patients with MG.

MORF2 tightly associates with MORF9 to regulate chloroplast RNA editing in Arabidopsis.

RNA editing in chloroplasts and mitochondria is performed by hypothetical editosomes. The MORF family proteins are essential components of these editosomes. In Arabidopsis, MORF2 and MORF9 are involved in the editing of most sites in chloroplasts. In this work, we performed immunoprecipitation and mass spectrometry assays of transgenic lines expressing MORF2-4xMYC and MORF9-4xMYC to identify interacting proteins. We found that MORF2 and MORF9 are present in the same complex. Blue-Native PAGE analysis of chloroplast protein complexes also revealed that both MORF2 and MORF9 are part of a complex of approximately 140 kDa, suggesting the existence of tight MORF2-MORF9 interaction in chloroplasts. The editing of ndhD-1 (ndhD-C2) site was reported to be blocked in both morf2 and morf9. RNA immunoprecipitation assays showed that MORF2 and MORF9 are tightly associated with the editing site of ndhD-1. However, in an RNA-EMSA assay MORF2 and MORF9 could not directly bind to transcripts harboring the editing site of ndhD-1. Taken together, these results indicate that the MORF2-MORF9 heterodimer is the core members of editosomes in chloroplasts, while they are not responsible for RNA editing site recognition.

Porphobilinogen deaminase HEMC interacts with the PPR-protein AtECB2 for chloroplast RNA editing.

The pentatricopeptide repeat-DYW protein AtECB2 affects plastid RNA editing at seven sites, including accD-794, accD-1568, ndhF-290, ndhG-50, petL-5, rpoA-200 and rpoC1-488. To understand the mechanism of its involvement in RNA editing, a transgenic line was constructed with AtECB2 fused to a 4xMYC tag that could complement the atecb2 phenotype. RNA immunoprecipitation analysis indicated that AtECB2 is associated with the transcripts of accD, ndhF, ndhG and petL. Co-immunoprecipitation and mass spectrometry experiments showed that multiple organelle RNA editing factor 2 (MORF2) and porphobilinogen deaminase HEMC are associated with AtECB2. Biochemical analysis showed that AtECB2 directly interacts with HEMC through its E domain, while HEMC interacts with MORF8/RIP1. Deletion analysis showed that the E domain is essential for RNA editing. The hemc-1 mutant showed an albino and seedling-lethal phenotype. Of the seven editing sites affected in atecb2, the editing of accD-794 and ndhF-290 was also reduced in hemc-1. RNA immunoprecipitation analysis suggested that HEMC is associated with the editing sites of ndhF transcripts. These results showed that both HEMC and multiple organellar RNA editing factor (MORF) proteins are associated with AtECB2 for RNA editing in plastids.

PPR protein PDM1/SEL1 is involved in RNA editing and splicing of plastid genes in Arabidopsis thaliana.

After transcription, most chloroplast precursor RNAs undergo further post-transcriptional processing including cleavage, editing, and splicing. Previous investigation has shown that the cleavage of the rpoA transcript and most editing sites, including accD-1, are defective in the knockout mutant of PDM1/SEL1, a PLS-type PPR protein, and that PDM1 is associated with the rpoA transcript. In this work, we found that the splicing of group II introns in trnK and ndhA is also affected in pdm1. Co-immunoprecipitation mass spectrometry experiments were performed to identify proteins that are associated with PDM1. We obtained 126 non-redundant proteins, of which MORF9 was reported to be involved in RNA editing in chloroplast. Yeast two-hybrid assays showed that PDM1 interacts directly with MORF9, MORF2, and MORF8. RNA immunoprecipitation showed that PDM1 associates with the transcripts of trnK and ndhA, as well as accD-1, suggesting that PDM1 is involved in RNA editing and splicing. Therefore, PDM1 is an important protein for post-transcriptional regulation in chloroplast.