Pharmacokinetics and dosage adjustment in patients with hepatic dysfunction

Pharmacokinetic/Pharmacodynamic Modelling and Simulation of Lusutrombopag, a Novel Thrombopoietin Receptor Agonist, for the Treatment of Thrombocytopenia in Patients with Chronic Liver Disease Undergoing Invasive Procedures

BACKGROUND

Patients with thrombocytopenia associated with chronic liver disease (CLD) are at greater risk of bleeding during invasive procedures. This study characterized the pharmacokinetic/pharmacodynamic (PK/PD) profile of lusutrombopag, a novel thrombopoietin-receptor agonist, using modelling and simulation, and evaluated the appropriate dose regimen for treatment of thrombocytopenia in CLD patients undergoing invasive procedures.

METHODS

A population PK/PD model was developed using plasma lusutrombopag concentrations from 78 healthy subjects and 349 CLD patients, as well as platelet counts from 347 of these 349 patients. Covariates were explored from subject characteristics. Monte-Carlo simulations were performed to assess a dose response for efficacy (platelet counts ≥ 50,000/μL) and a risk for platelet overshooting (platelet counts > 200,000/μL).

RESULTS

Visual predictive checks indicated the developed models described the PK/PD profile of lusutrombopag well. In the simulations, without stopping criteria, lusutrombopag 3 mg once daily for 7 days before scheduled invasive procedures provided effective platelet response (85.2% probability for efficacy). The probability of platelet overshooting was 1.2%, indicating that platelet monitoring is not necessary. Although body weight was an influential covariate on the pharmacokinetics of lusutrombopag, individually estimated peak platelet counts overlapped among the body weight groups, suggesting no clinically significant effect on body weight.

CONCLUSION

The modelling and simulation support lusutrombopag 3 mg once daily for 7 days without platelet monitoring.

Optimizing Estimated Glomerular Filtration Rate to Support Adult to Pediatric Pharmacokinetic Bridging Studies in Patients with Cystic Fibrosis

BACKGROUND

The estimated glomerular filtration rate (eGFR) is often used to model drug clearance (CL) and scale doses across age and body size. Over their lifetime, patients with cystic fibrosis (CF) receive repeated courses of tobramycin, an antibiotic with eGFR-dependent CL, for the treatment of pulmonary exacerbations. Tobramycin population pharmacokinetic (PK) modeling can be used to decipher the best approach to define eGFR for pediatric bridging studies.

METHODS

Inpatients with CF who received intravenous tobramycin between 1 January 2006 and 30 May 2018 were eligible for inclusion. Encounters without tobramycin concentration measurement or missing covariate data were excluded. Population PK analysis was performed using NONMEM.Covariate models were built  following identification of the base model, with specific emphasis on the effect of different methods of estimating renal function as a covariate of tobramycin CL.

RESULTS

A total of 296 CF patients contributed 1029 care encounters (420 pediatric, 609 adult) and 4352 tobramycin concentrations to this analysis. The median (minimum, maximum) age at encounter was 19 years (0.2, 60), with serum creatinine of 0.60 mg/dL (0.10, 3.41). A two-compartment model best described the observed data, with height and eGFR as significant covariates of tobramycin CL. eGFR was best modeled using a combination of the modified Schwartz and Chronic Kidney Disease Epidemiology Collaboration (CKDEPI) equations expressed in absolute units.

CONCLUSIONS

The CKDEPI equation bridges PK data generated in adults to adolescents with CF better than the current regulatory standard. The eGFR should be expressed in absolute units (mL/min) for PK analyses.

Therapeutic efficacy of lenvatinib in hepatocellular carcinoma patients with portal hypertension

AIM

Preserved liver function may be an important factor affecting therapeutic efficacy in hepatocellular carcinoma patients treated with lenvatinib, but not all patients can be treated while preserving liver function. This study evaluated the therapeutic efficacy of lenvatinib in patients with poor liver function with and without portal hypertension.

METHODS

This prospectively registered multicenter study analyzed 93 patients treated with lenvatinib. Progression-free survival was compared between patients with and without advanced portal hypertension according to baseline liver function. Advanced portal hypertension was defined as having both splenomegaly and any portosystemic collaterals.

RESULTS

A total of 37 patients (40.7%) had advanced portal hypertension. Progression-free survival did not differ between patients with and without advanced portal hypertension in the entire cohort (median 7.6 vs. 4.1 months, respectively; P = 0.148), but was significantly longer in patients with advanced portal hypertension than in those without advanced portal hypertension in the albumin-bilirubin grade 2 or 3 group (median 7.6 vs. 2.1 months, respectively; P = 0.016). In a multivariate analysis, the presence of advanced portal hypertension was identified as the only significant predictor associated with prolonged progression-free survival in the albumin-bilirubin grade 2 or 3 group.

CONCLUSIONS

Advanced portal hypertension was associated with the therapeutic efficacy of lenvatinib in controlling the progression of hepatocellular carcinoma in patients with poor liver function.

Open-label, Single-dose Studies of the Pharmacokinetics of Edaravone in Subjects with Mild, Moderate, or Severe Hepatic Impairment Compared to Subjects with Normal Hepatic Functioning

PURPOSE

Two studies were conducted to assess the pharmacokinetic (PK) properties and tolerability of edaravone in Japanese subjects with mild to moderate hepatic impairment or normal hepatic functioning (study 1), and in white subjects with severe hepatic impairment compared to subjects with normal hepatic functioning (study 2).

METHODS

Studies 1 and 2 were multicenter, open-label, single-dose studies that included subjects aged 18-75 years. In study 1, subjects were stratified into 3 different groups of hepatic functioning according to Child-Pugh score: mild hepatic impairment, score 5 or 6 (n = 8); moderate hepatic impairment, score 7-9 (n = 6); or normal hepatic functioning (n = 8). In study 2, subjects had severe hepatic impairment (Child-Pugh score 10-14; n = 6) or normal hepatic functioning (n = 6). In both studies, all subjects were given edaravone 30 mg IV infused over 60 min on the morning of day 1. Blood samples for use in PK analyses were collected from days 1-3. The PK properties (C_max, AUC_0-last, and AUC_0-∞) of edaravone and its sulfate conjugate metabolite were measured.

FINDINGS

In study 1, the geometric least-squares mean (GLSM) C_max and AUC_0-∞ of unchanged edaravone were 1.203- and 1.065-fold greater, respectively, in subjects with mild hepatic impairment versus normal hepatic functioning, and were 1.235- and 1.142-fold greater, respectively, in subjects with moderate hepatic impairment versus normal hepatic functioning. In study 2, GLSM C_max and AUC_0-∞ of unchanged edaravone were 1.203- and 1.190-fold greater, respectively, in subjects with severe hepatic impairment versus normal hepatic functioning. In both studies the AUC_0-last, AUC_0-∞, unbound AUC from time zero to infinity, and C_max of unchanged edaravone were increased slightly with increases in Child-Pugh classification. No adverse events considered related to edaravone were reported, except for 1 case of sinus bradycardia in a subject with normal hepatic functioning in study 2. The event was moderate in severity, considered as possibly related to edaravone, and resolved during the study.

IMPLICATIONS

Mild to moderate and severe hepatic impairment had no apparent clinically significant effects on the PK profile of edaravone in Japanese and white subjects, respectively, relative to individuals with normal hepatic functioning, and there were no notable tolerability concerns. Thus, edaravone dosage adjustments are unlikely to be needed in edaravone-treated patients with mild to moderate and severe hepatic impairment. ClinicalTrials.gov identifiers: NCT03289234 (mild to moderate hepatic impairment) and NCT03664544 (severe hepatic impairment).

Pharmacokinetics of the BCL-2 Inhibitor Venetoclax in Subjects with Hepatic Impairment

INTRODUCTION

Venetoclax is a selective B cell lymphoma-2 inhibitor. It is approved for treatment of chronic lymphocytic leukemia and is being investigated for other hematological malignancies. Venetoclax is predominantly eliminated by the liver; therefore, there is a need to investigate the effect of hepatic insufficiency on venetoclax pharmacokinetics.

METHODS

A phase I study was carried out in 24 women with normal hepatic function or mild, moderate, or severe hepatic impairment (based on Child-Pugh scores), who received a single 50 mg dose of venetoclax with a low-fat meal. Blood samples were collected up to 120 h after venetoclax administration. Pharmacokinetic parameters were estimated using non-compartmental methods.

RESULTS

Venetoclax maximum observed plasma concentration (C_max) and area under the plasma concentration-time curve (AUC) in subjects with mild or moderate hepatic impairment were similar to subjects with normal hepatic function. Mean venetoclax AUC in subjects with severe hepatic impairment was 2.3- to 2.7-fold higher than in subjects with normal hepatic function. The half-life of venetoclax in subjects with severe hepatic impairment was approximately two-fold longer than in subjects with normal hepatic function and subjects with mild or moderate hepatic impairment. Unbound fractions of venetoclax in subjects with mild, moderate, and severe hepatic impairment were similar to the subjects with normal hepatic function. No significant adverse safety events were reported.

CONCLUSIONS

No venetoclax dosage adjustment is required in subjects with mild or moderate hepatic impairment. In subjects with severe hepatic impairment, a 50% dose reduction of venetoclax is recommended to account for higher exposures and the longer half-life.

Prediction of lisinopril pediatric dose from the reference adult dose by employing a physiologically based pharmacokinetic model

Background

This study aimed to assess the pediatric lisinopril doses using an adult physiological based pharmacokinetic (PBPK) model. As the empirical rules of dose calculation cannot calculate gender-specific pediatric doses and ignores the age-related physiological differences.

Methods

A PBPK model of lisinopril for the healthy adult population was developed for oral (fed and fasting) and IV administration using PK-Sim MoBI® and was scaled down to a virtual pediatric population for prediction of lisinopril doses in neonates to infants, infants to toddler, children at pre-school age, children at school age and the adolescents. The pharmacokinetic parameters were predicted for the above groups at decremental doses of 20 mg, 10 mg, 5 mg, 2.5 mg, and 1.5 mg in order to accomplish doses producing the pharmacokinetic parameters, similar (or comparable) to that of the adult population. The above simulated pediatric doses were compared to the doses computed using the conventional four methods, such as Young’s rule, Clark’s rule, and weight-based and body surface area-based equations and the dose reported in different studies.

Results

Though the doses predicted for all subpopulations of children were comparable to those calculated by Young’s rule, yet the conventional methods overestimated the pediatric doses when compared to the respective PBPK-predicted doses. The findings of previous real time pharmacokinetic studies in pediatric patients supported the present simulated dose.

Conclusion

Thus, PBPK seems to have predictability potential for pediatric dose since it takes into consideration the physiological changes related to age and gender.

Effect of Hepatic Impairment on Cobimetinib Pharmacokinetics: The Complex Interplay Between Physiological Changes and Drug Characteristics

Cobimetinib is a kinase inhibitor indicated for use in combination with vemurafenib for treatment of unresectable/metastatic melanoma with specific BRAF mutations. Cobimetinib is extensively metabolized in liver; thus, patients with hepatic impairment (HI) might have increased cobimetinib exposure. In this study, we investigated the impact of HI on the pharmacokinetics (PK) and safety of cobimetinib. Subjects with normal hepatic function and mild to severe HI were enrolled. All subjects received a single oral dose of 10 mg cobimetinib, and serial blood samples were collected at specified times. Cobimetinib PK in subjects with mild and moderate HI was similar to that in those with normal liver function. However, subjects with severe HI, on average, showed ∼30% lower total AUC_0-∞ and ∼2-fold higher unbound AUC_0-∞ compared with those with normal hepatic function. These exposure differences can be explained by lower albumin levels observed in subjects with severe HI, the strong correlation between albumin level and the unbound fraction and the general PK variability of cobimetinib. In addition, previous studies with cobimetinib showed a lack of an exposure-response relationship for efficacy and safety. Therefore, collectively, our results suggest that the starting dose for patients with hepatic impairment can be the same as that for those with normal hepatic function.

Nursing Personnel in the Era of Personalized Healthcare in Clinical Practice

Personalized, stratified, or precision medicine (PM) introduces a new era in healthcare that tries to identify and predict optimum treatment outcomes for a patient or a cohort. It also introduces new scientific terminologies regarding therapeutic approaches and the need of their adoption from healthcare providers. Till today, evidence-based practice (EBP) was focusing on population averages and their variances among cohorts for clinical values that are essential for optimizing healthcare outcome. It can be stated that EBP and PM are complementary approaches for a modern healthcare system. Healthcare providers through EBP often see the forest (population averages) but miss the trees (individual patients), whereas utilization of PM may not see the forest for the trees. Nursing personnel (NP) play an important role in modern healthcare since they are consulting, educating, and providing care to patients whose needs often needs to be individualized (personalized nursing care, PNC). Based on the clinical issues earlier addressed from clinical pharmacology, EBP, and now encompassed in PM, this review tries to describe the challenges that NP have to face in order to meet the requisites of the new era in healthcare. It presents the demands that should be met for upgrading the provided education and expertise of NP toward an updated role in a modern healthcare system.

Dose recommendations for anticancer drugs in patients with renal or hepatic impairment

Renal or hepatic impairment is a common comorbidity for patients with cancer either because of the disease itself, toxicity of previous anticancer treatments, or because of other factors affecting organ function, such as increased age. Because renal and hepatic function are among the main determinants of drug exposure, the pharmacokinetic profile might be altered for patients with cancer who have renal or hepatic impairment, necessitating dose adjustments. Most anticancer drugs are dosed near their maximum tolerated dose and are characterised by a narrow therapeutic index. Consequently, selecting an adequate dose for patients who have either hepatic or renal impairment, or both, is challenging and definitive recommendations on dose adjustments are scarce. In this Review, we discuss the effect of renal and hepatic impairment on the pharmacokinetics of anticancer drugs. To guide clinicians in selecting appropriate dose adjustments, information from available drug labels and from the published literature were combined to provide a practical set of recommendations for dose adjustments of 160 anticancer drugs for patients with hepatic and renal impairment.

Direct Comparison of Total Clearance Prediction: Computational Machine Learning Model versus Bottom-Up Approach Using In Vitro Assay

The in vitro-in vivo extrapolation (IVIVE) approach for predicting total plasma clearance (CL_tot) has been widely used to rank order compounds early in discovery. More recently, a computational machine learning approach utilizing physicochemical descriptors and fingerprints calculated from chemical structure information has emerged, enabling virtual predictions even earlier in discovery. Previously, this approach focused more on in vitro intrinsic clearance (CL_int) prediction. Herein, we directly compare these two approaches for predicting CL_tot in rats. A structurally diverse set of 1114 compounds with known in vivo CL_tot, in vitro CL_int, and plasma protein binding was used as the basis for this evaluation. The machine learning models were assessed by validation approaches using the time- and cluster-split training and test sets, and five-fold cross validation. Assessed by five-fold validation, the random forest regression (RF) and radial basis function (RBF) models demonstrated better prediction performance in eight attempted machine learning models. The CL_tot values predicted by the RF and RBF models were within two-fold of the observed values for 67.7 and 71.9% of cluster-split test set compounds, respectively, while the predictivity was worse in the time-split dataset. The predictivity of both models tended to be improved by incorporating in vitro parameters, unbound fraction in plasma (f_u,p), and CL_int. CL_tot prediction utilizing in vitro CL_int and the well-stirred model, correcting for the fraction unbound in blood, was substantially worse compared to machine learning approaches for the same cluster-split test set. The reason that CL_tot is underestimated by IVIVE is not fully explained by considering the calculated microsomal unbound fraction (cf_u,mic), extended clearance classification system (ECCS), and omitting high clearance compounds in excess of hepatic blood flow. The analysis suggests that in silico machine learning models may have the power to reduce reliance on or replace in vitro and in vivo studies for chemical structure optimization in early drug discovery.

Pharmacokinetics and tolerability of fedratinib, an oral, selective Janus kinase 2 inhibitor, in subjects with renal or hepatic impairment

PURPOSE

Fedratinib is an oral, selective Janus kinase 2 inhibitor that is approved in the United States for the treatment of patients with intermediate-2 or high-risk myelofibrosis. Pharmacokinetics and tolerability of fedratinib in subjects with renal impairment (RI) and hepatic impairment (HI) were evaluated in two separate studies.

METHODS

In the renal study, male and female subjects with stable, chronic mild, moderate, and severe RI, as well as those with end-stage renal disease, were included. The hepatic study included subjects with stable, chronic mild HI. Both were phase 1, multicenter, open-label, single-dose studies, and included matched healthy subjects. Subjects received a single oral dose of fedratinib 300 mg on day 1, were discharged on day 4, returned for clinical visits on days 5-12, and had their end-of-study visit between days 14 and 16.

RESULTS

Thirty-six and 17 subjects were included in the renal and hepatic studies, respectively. In the renal study, fedratinib area under the plasma concentration-time curve from time 0 to infinity (AUC_inf) was 1.9- and 1.5-fold higher in subjects with severe and moderate RI, respectively, than in matched healthy subjects. In the hepatic study, fedratinib AUC_inf did not appreciably differ between subjects with mild HI and matched healthy subjects. Overall, most treatment-emergent adverse events were gastrointestinal and mild.

CONCLUSION

Mild RI and HI do not necessitate fedratinib dosage adjustments. Subjects with moderate RI should be monitored (with dosage adjustments made as necessary), whereas those with severe RI should receive a daily dose of 200 mg, reduced from the indicated dose of 400 mg.

Pharmacokinetic-Based Drug-Drug Interactions with Anaplastic Lymphoma Kinase Inhibitors: A Review

Anaplastic lymphoma kinase (ALK) inhibitors are important treatment options for non-small-cell lung cancer (NSCLC), associated with ALK gene rearrangement. Patients with ALK gene rearrangement show sensitivity to and benefit clinically from treatment with ALK tyrosine kinase inhibitors (ALK-TKIs). To date, crizotinib, ceritinib, alectinib, brigatinib, lorlatinib, and entrectinib have received approval from the US Food and Drug Administration and/or the European Medicines Agency for use during the treatment of ALK-gene-rearrangement forms of NSCLC. Although the oral route of administration is convenient and results in good compliance among patients, oral administration can be affected by many factors, such as food, intragastric pH, cytochrome P450 enzymes, transporters, and p-glycoprotein. These factors can result in increased risks for serious adverse events or can lead to reduced therapeutic effects of ALK-TKIs. This review characterizes and summarizes the pharmacokinetic parameters and drug–-drug interactions associated with ALK-TKIs to provide specific recommendations for oncologists and clinical pharmacists when prescribing ALK-TKIs.

Simulation of the Pharmacokinetics of Oseltamivir and Its Active Metabolite in Normal Populations and Patients with Hepatic Cirrhosis Using Physiologically Based Pharmacokinetic Modeling

Oseltamivir is a neuraminidase inhibitor widely used to treat and prevent influenza A and B infections, although its safety and pharmacokinetics have not been evaluated in patients with severe hepatic impairment. A physiologically based pharmacokinetic (PBPK) model of the prodrug oseltamivir and its active metabolite, oseltamivir carboxylate (OC), was established and validated to simulate their disposition in adults and predict the exposure in patients with Child-Pugh C cirrhosis (CP-C). The simulated results from PBPK modeling and the observed data after oral administration of various oseltamivir regimens were consistent according to the fold error values of less than 2. Furthermore, the clinical observations published in the literature were comparable with our pharmacokinetic predictions. In patients with CP-C, the oseltamivir C_max was approximately 2-fold increased, and its AUC was approximately 6-fold higher compared with those in normal subjects. In contrast, the AUC of OC in CP-C patients did not differ significantly from that in normal subjects, whereas its C_max was reduced by approximately 30% in the patients. Examination of drug exposure in different health conditions indicated that the oseltamivir exposure was significantly increased in conditions with elevated cirrhosis severity, which might be associated with a higher risk of adverse drug effects, e.g., neuropsychiatric adverse events (NPAEs). In conclusion, the pharmacokinetics of oseltamivir and OC were correctly predicted by PBPK modeling. The model further predicted that the pharmacokinetics of oseltamivir might be altered in liver cirrhosis, depending on the degree of severity.

Etoposide dosage adjustment in two patients with neuroendocrine tumors and severe liver impairment

Introduction

Limited data are available on dosing etoposide in patients with liver impairment.

Case report

We report the dosing strategies for etoposide utilized in two patients with neuroendocrine tumors and severe liver impairment.

Management and outcomes

Treatment consisted of platinum-based chemotherapy regimens, with the decision of whether to administer etoposide and at what doses being based on the liver function before each chemotherapy cycle. By the end of treatment, total bilirubin was normal, and the performance status of both patients had improved, with stable computed tomography scan findings.

Discussion

The reported two cases suggest that the administration of etoposide at reduced doses with close monitoring in patients with neuroendocrine tumors and severe liver impairment may still be considered as an option and may improve outcomes.

Creation of a score to predict risk of high conscious sedation requirements in patients undergoing endoscopy

BACKGROUND AND AIMS

The administration of intravenous conscious sedation to patients undergoing GI endoscopy carries a risk of cardiopulmonary adverse events. Our study aim was to create a score that stratifies the risk of occurrence of either high-dose conscious sedation requirements or a failed procedure.

METHODS

Patients receiving endoscopy via endoscopist-directed conscious sedation were included. The primary outcome was occurrence of sedation failure, which was defined as one of the following: (1) high-dose sedation, (2) the need for benzodiazepine/narcotic reversal agents, (3) nurse-documented poor patient tolerance to the procedure, or (4) aborted procedure. High-dose sedation was defined as >10 mg of midazolam and/or >200 μg of fentanyl or the meperidine equivalent. Patients with sedation failure (n = 488) were matched to controls (n = 976) without a sedation failure by endoscopist and endoscopy date.

RESULTS

Significant associations with sedation failure were identified for age, sex, nonclonazepam benzodiazepine use, opioid use, and procedure type (EGD, colonoscopy, or both). Based on these 5 variables, we created the high conscious sedation requirements (HCSR) score, which predicted the risk of sedation failure with an area under the curve of 0.70. Compared with the patients with a risk score of 0, risk of a sedation failure was highest for patients with a score ≥3.5 (odds ratio, 17.31; P = 2 × 10^-14). Estimated area under the curve of the HCSR score was 0.68 (95% confidence interval, 0.63-0.72) in a validation series of 250 cases and 250 controls.

CONCLUSIONS

The HCSR risk score, based on 5 key patient and procedure characteristics, can function as a useful tool for physicians when discussing sedation options with patients before endoscopy.

Pharmacokinetics of intravenous voriconazole in patients with liver dysfunction: A prospective study in the intensive care unit

OBJECTIVES

To characterize the pharmacokinetics (PK) of intravenous voriconazole (VRC) in critically ill patients with liver dysfunction.

METHODS

Patients with liver dysfunction in the intensive care unit (ICU) were included prospectively. The Child-Pugh score was used to categorize the degree of liver dysfunction. The initial intravenous VRC dosing regimen comprised a loading dose of 300 mg every 12 h for the first 24 h, followed by 200 mg every 12 h. The first PK curves (PK curve 1) were drawn within one dosing interval of the first dose for 17 patients; the second PK curves (PK curve 2) were drawn within one dosing interval after a minimum of seven doses for 12 patients. PK parameters were estimated by non-compartmental analysis.

RESULTS

There were good correlations between the area under the curve (AUC_0-12) of PK curve 2 and the corresponding trough concentration (C₀) and peak concentration (C_max) (r² = 0.951 and 0.963, respectively; both p < 0.001). The median half-life (t_1/2) and clearance (CL) of patients in Child-Pugh class A (n = 3), B (n = 5), and C (n = 4) of PK curve 2 were 24.4 h and 3.31 l/h, 29.1 h and 2.54 l/h, and 60.7 h and 2.04 l/h, respectively. In the different Child-Pugh classes, the CL (median) of PK curve 2 were all lower than those of PK curve 1. The apparent steady-state volume of distribution (V_ss) of PK curve 1 was positively correlated with actual body weight (r² = 0.450, p = 0.004). The median first C₀ of 17 patients determined on day 5 was 5.27 (2.61) μg/ml, and 29.4% of C₀ exceeded the upper limit of the therapeutic window (2-6 μg/ml).

CONCLUSIONS

The CL of VRC decreased with increasing severity of liver dysfunction according to the Child-Pugh classification, along with an increased t_1/2, which resulted in high plasma exposure of VRC. Adjusted dosing regimens of intravenous VRC should be established based on Child-Pugh classes for these ICU patients, and plasma concentrations should be monitored closely to avoid serious adverse events.

Understanding Idiosyncratic Toxicity: Lessons Learned from Drug-Induced Liver Injury

Idiosyncratic adverse drug reactions (IADRs) encompass a diverse group of toxicities that can vary by drug and patient. The complex and unpredictable nature of IADRs combined with the fact that they are rare makes them particularly difficult to predict, diagnose, and treat. Common clinical characteristics, the identification of human leukocyte antigen risk alleles, and drug-induced proliferation of lymphocytes isolated from patients support a role for the adaptive immune system in the pathogenesis of IADRs. Significant evidence also suggests a requirement for direct, drug-induced stress, neoantigen formation, and stimulation of an innate response, which can be influenced by properties intrinsic to both the drug and the patient. This Perspective will provide an overview of the clinical profile, mechanisms, and risk factors underlying IADRs as well as new approaches to study these reactions, focusing on idiosyncratic drug-induced liver injury.

Medication safety in patients with hepatic impairment: A survey of community pharmacists' knowledge level and their practice in caring for these patients

Aims

To study community pharmacists' level of knowledge on medication safety in patients with hepatic impairment and their practice in caring for these patients.

Methods

Pharmacists from Dutch community pharmacies (n = 1545) were invited to participate in an online survey. The survey consisted of 27 questions covering 2 main topics: knowledge and current practice. The level of knowledge was measured by a 6‐item knowledge test. Multiple linear regression was used to identify predictors of correctly answered responses.

Results

In total, 338 pharmacists (22%) completed the questionnaire. The mean knowledge score was 2.8 (standard deviation 1.6). Only 30.3% of respondents were able to appropriately advise on use of analgesics in severe cirrhosis. Postgraduate education on hepatic impairment, knowledge of recently developed practical guidance, and fewer years of practice were associated with a higher level of knowledge. In total, 70.4% indicated to evaluate medication safety in a patient with hepatic impairment at least once weekly. In the past 6 months, 83.3% of respondents consulted a prescriber about a patient with hepatic impairment. Frequently encountered barriers in practice were insufficient knowledge on the topic and a lack of essential patient information (i.e. diagnosis and severity of the impairment).

Conclusion

Community pharmacists regularly evaluate the safety of medication in patients with hepatic impairment, yet their level of knowledge was insufficient and additional education is needed. Pharmacists experienced several difficulties in providing pharmaceutical care. If these issues are resolved, pharmacists can play a more active role in ensuring medication safety in their patients with hepatic impairment.

Prevalence of Drug Prescriptions and Potential Safety in Patients with Cirrhosis: A Retrospective Real-World Study

Introduction

Patients with cirrhosis are at risk for adverse drug reactions (ADRs) due to altered pharmacokinetics and pharmacodynamics. We aimed to determine the prevalence of drug prescriptions and the potential safety of these prescriptions in a real-world cohort of patients with cirrhosis.

Methods

This was a retrospective cohort study based on linked real-world data from the Out-patient Pharmacy Database and the Hospitalisation Database of the PHARMO Database Network. Patients with a diagnosis of cirrhosis between January 1998 and December 2015 were included. Follow-up ended when the patient underwent a liver transplant, died, transferred out of the database, or on 31 December 2015. Prescription data were derived from a community pharmacy database and were compared with our previously developed safety recommendations for 209 drugs.

Results

In total, 5618 patients were included and followed for a median of 3 years (interquartile range [IQR] 1–7). In the first year after the diagnosis, patients used a median of nine drugs (IQR 5–14), with proton pump inhibitors (prevalence 53.9%), aldosterone antagonists (43.6%), and sulfonamide diuretics (41.3%) being the most commonly used drug groups. Almost half (48.3%) of 102,927 prescriptions consisted of drugs with a safety recommendation. The prevalence of potentially unsafe drug use was 60.0% during the total follow-up. Three nonsteroidal anti-inflammatory drugs (NSAIDs) were among the five most commonly used potentially unsafe drugs.

Conclusions

Patients with cirrhosis use a large number of drugs. Almost two-thirds of patients in our cohort used potentially unsafe drugs. To prevent ADRs in these frail patients, personalised pharmacotherapy is necessary.

Electronic supplementary material

The online version of this article (10.1007/s40264-018-0744-1) contains supplementary material, which is available to authorized users.

Current Treatment Options for HCC: From Pharmacokinetics to Efficacy and Adverse Events in Liver Cirrhosis

BACKGROUND

Hepatocellular carcinoma (HCC) is among the world's most common cancers. For over ten years, the only medical treatment for it has been the multikinase inhibitor Sorafenib. Currently, however, other first or second-line therapeutic options have also shown efficacy against HCC, such as multikinase inhibitors (Regorafenib, Lenvatinib, and Cabozantinib), a monoclonal antibody against the vascular endothelial growth factor receptor 2 (Ramucirumab), and immune-checkpoint inhibitors (Nivolumab, Pembrolizumab, Ipilimumab).

AIM

The aim of this paper is to review the metabolic pathways of drugs that have been tested for the treatment of HCC and the potential influence of liver failure over those pathways.

METHODS

The Food and Drug Administration (FDA)'s and European Medicines Agency (EMA)'s datasheets, results from clinical trials and observational studies have been reviewed.

RESULTS

This review summarizes the current knowledge regarding targets, metabolic pathways, drug interactions, and adverse events of medical treatments for HCC in cirrhotic patients.

CONCLUSION

The new scenario of systemic HCC therapy includes more active drugs with different metabolic pathways and different liver adverse events. Clinical and pharmacological studies providing more data on the safety of these molecules are urgently needed.

Pharmacokinetics and Safety of Single-Dose Esaxerenone in Japanese Subjects with Mild to Moderate Hepatic Impairment

Introduction

The mineralocorticoid receptor (MR) blocker esaxerenone is a new treatment for hypertension in Japan and under development for treatment of diabetic nephropathy. Hepatic impairment is known to impact the pharmacokinetics (PKs) of other MR blocking drugs. The aim of the present study was to characterise the PKs and safety of a single oral dose of esaxerenone in Japanese subjects with mild–moderate hepatic impairment.

Methods

In this open-label, parallel-group study, subjects with mild (Child–Pugh grade A) or moderate (grade B) hepatic impairment, and healthy controls with normal hepatic function matched by age and BMI (all groups n = 6), received a single 2.5-mg oral dose of esaxerenone. Plasma concentrations were measured by liquid chromatography–tandem mass spectrometry, and PK parameters were calculated using non-compartmental analysis.

Results

Geometric least-squares mean (GLSM) ratios (90% confidence intervals [CIs]) for area under the plasma concentration–time curve (up to the last quantifiable time, up to infinity) in subjects with mild hepatic impairment versus normal hepatic function were 0.837 (0.637, 1.099) and 0.824 (0.622, 1.092), respectively. Corresponding values for moderate hepatic impairment versus normal hepatic function were 1.078 (0.820, 1.415) and 1.098 (0.829, 1.454). GLSM ratios (90% CIs) for peak plasma concentration (C_max) were 0.959 (0.778, 1.182) for mild hepatic impairment versus normal hepatic function and 0.804 (0.653, 0.992) for moderate hepatic impairment versus normal hepatic function. Time to C_max and clearance values were comparable between groups. The incidence of adverse events (AEs) was 16.7% in the moderate hepatic impairment and normal hepatic function groups. One serious AE (hepatic encephalopathy) occurred in one subject with moderate hepatic impairment.

Conclusions

Mild to moderate hepatic impairment had no clinically relevant effect on esaxerenone exposure. Esaxerenone dosage adjustment based on PKs is unlikely to be needed in patients with mild to moderate hepatic impairment.

Trial Registration

JapicCTI-163339.

Funding

Daiichi Sankyo Co., Ltd.

Development and Evaluation of Physiologically Based Pharmacokinetic Drug-Disease Models for Predicting Rifampicin Exposure in Tuberculosis and Cirrhosis Populations

The physiologically based pharmacokinetic (PBPK) approach facilitates the construction of novel drug–disease models by allowing incorporation of relevant pathophysiological changes. The aim of the present work was to explore and identify the differences in rifampicin pharmacokinetics (PK) after the application of its single dose in healthy and diseased populations by using PBPK drug–disease models. The Simcyp^® simulator was used as a platform for modeling and simulation. The model development process was initiated by predicting rifampicin PK in healthy population after intravenous (i.v) and oral administration. Subsequent to successful evaluation in healthy population, the pathophysiological changes in tuberculosis and cirrhosis population were incorporated into the developed model for predicting rifampicin PK in these populations. The model evaluation was performed by using visual predictive checks and the comparison of mean observed/predicted ratios (ratio_(Obs/pred)) of the PK parameters. The predicted PK parameters in the healthy population were in adequate harmony with the reported clinical data. The incorporation of pathophysiological changes in albumin concentration in the tuberculosis population revealed improved prediction of clearance. The developed PBPK drug–disease models have efficiently described rifampicin PK in tuberculosis and cirrhosis populations after administering single drug dose, as the ratio_(Obs/pred) for all the PK parameters were within a two-fold error range. The mechanistic nature of the developed PBPK models may facilitate their extension to other diseases and drugs.

Surgery in Patients with Portal Hypertension

Patients with portal hypertension will increasingly present for nontransplant surgery because of the increasing incidence of, and improving long-term survival for, chronic liver disease. Such patients have increased perioperative morbidity and mortality caused by the systemic pathophysiology of liver disease. Preoperative assessment should identify modifiable causes of liver injury and distinguish between compensated and decompensated cirrhosis. Risk stratification, which is crucial to preparing patients and their families for surgery, relies on scores such as Child-Turcotte-Pugh and Model for End-stage Liver Disease to translate disease severity into quantified outcomes predictions. Risk factors for postoperative complications should also be recognized.

A phase I pharmacokinetic study of belinostat in patients with advanced cancers and varying degrees of liver dysfunction

AIMS

The histone deacetylase inhibitor belinostat has activity in various cancers. Because belinostat is metabolized by the liver, reduced hepatic clearance could lead to excessive drug accumulation and increased toxicity. Safety data in patients with liver dysfunction are needed for this drug to reach its full potential in the clinic.

METHODS

We performed a phase 1 trial to determine the safety, maximum tolerated dose (MTD) and pharmacokinetics of belinostat in patients with advanced cancer and varying degrees of liver dysfunction.

RESULTS

Seventy-two patients were enrolled and divided into cohorts based on liver function. In patients with mild dysfunction, the MTD was the same as the recommended phase 2 dose (1000 mg/m2 /day). Belinostat was well tolerated in patients with moderate and severe liver dysfunction, although the trial was closed before the MTD in these cohorts could be determined. The mean clearance of belinostat was 661 mL/min/m2 in patients with normal liver function, compared to 542, 505 and 444 mL/min/m2 in patients with mild, moderate and severe hepatic dysfunction. Although this trial was not designed to assess clinical activity, of the 47 patients evaluable for response, 13 patients (28%) experienced stable disease.

CONCLUSION

While a statistically significant difference in clearance indicates increased belinostat exposure with worsening liver function, no relationship was observed between belinostat exposure and toxicity. An assessment of belinostat metabolites revealed significant differences in metabolic pathway capability in patients with differing levels of liver dysfunction. Further studies are needed to establish formal dosing guidelines in this patient population.

Evaluation of Information in Summaries of Product Characteristics (SmPCs) on the Use of a Medicine in Patients With Hepatic Impairment

Background: In 2005, the European Medicines Agency (EMA) released guidance on pharmacokinetic studies in patients with hepatic impairment. This guidance describes the design of these studies and what information should be presented in the Summary of Product Characteristics (SmPC). We aim to evaluate the availability and clinical applicability of information on medicine use in patients with hepatic impairment in SmPCs and registrational dossiers of recently approved medicines. Methods: We reviewed SmPC information on use in patients with hepatic impairment of 51 new medicines authorized between 2015 and 2017. Per medicine, we assessed the availability of nine information items derived from the EMA guidance, i.e. type of hepatic disease studied; stratification by severity of hepatic impairment; influence of hepatic impairment on the pharmacokinetics; safety advice in mild, moderate, and severe hepatic impairments; and dosing recommendation in mild, moderate, and severe hepatic impairments. If unavailable, the European Public Assessment Report (EPAR) and study report were consulted consecutively. Of available items, clinical applicability was assessed by labeling information as "clear" or "ambiguous". Results: Of 51 medicines, 15 had no pharmacokinetic study in patients with hepatic impairment described in their SmPC. The other 36 SmPCs contained on average seven of the nine information items (range 4-9). One SmPC contained all 9 items, and after consulting, the study reports, 11 SmPCs were complete. The item "type of hepatic disease studied" was available in one SmPC, though it could be retrieved in 21 study reports. Regarding clinical applicability, there was no medicine with all information items available and clearly formulated in the SmPC. A total of 12 medicines (33%) contained only clearly formulated information, while 24 (67%) contained at least one ambiguously formulated information item (range 0-4). Items often ambiguously formulated were: "definition of mild, moderate, and severe hepatic impairment" (15 ambiguous SmPCs) and "safety advice in severe hepatic impairment" (17 ambiguous SmPCs). Conclusion: While SmPCs contain a large part of information requested by the EMA, clinical applicability seems low, as it is often unclear to which specific type of hepatic disease patient the advice applies. This can negatively influence the practical use by healthcare professionals.

A Pharmacology Perspective of Simultaneous Tuberculosis and Hepatitis C Treatment

Tuberculosis (TB) and hepatitis C virus (HCV) infection are both major public health problems. Despite high rates of co-infection there is scarce literature addressing the convergence of the two diseases. One particularly unexplored area is the potential for simultaneous treatment of TB and HCV which would allow for leveraging an extensive global TB treatment infrastructure to help scale up HCV treatment. We review the drug metabolism of anti-TB and HCV drugs and the known and potential drug-drug interactions between recommended HCV regimens and individual anti-TB drugs. Rifampin is the only anti-TB drug to have been formally studied for potential drug interactions with anti-HCV direct-acting antivirals (DAAs) and existing data precludes these combinations. However, based on known pathways of drug metabolism and enzyme effects, the combination of HCV DAA regimens with all other anti-TB drugs may be feasible. Pharmacokinetic studies are needed next to help move co treatment regimens forward for clinical use among patients coinfected with TB and HCV.

Plasma Protein and Lipoprotein Binding of Cis- and Trans-Permethrin and Deltamethrin in Adult Humans and Rats

The majority of residents of the United States, Canada, and Europe are exposed to pyrethroids, the most commonly used class of insecticides. Surprisingly little is known about key aspects of their pharmacokinetics, including their mode of transport in the systemic circulation. This study tested the hypothesis that pyrethroids are transported by both plasma lipoproteins and proteins, similarly to other highly lipophilic environmental contaminants. Other aims were to characterize the binding of representative type I and II pyrethroids, and to compare their binding to rat versus human plasma. Binding of 14C-labeled cis-permethrin (CIS), trans-permethrin (TRANS) and deltamethrin (DLM) to proteins and lipoproteins was measured by sequential extraction of spiked plasma with isooctane, 2-octanol, and acetonitrile. Binding of DLM, CIS, and TRANS to plasma proteins and lipoproteins was linear from 250 to 750 nM; concentrations present in the plasma of orally dosed rats. Binding of DLM to high-density lipoprotein was twice that to low-density lipoprotein. Binding of DLM, CIS, and TRANS was ∼2-fold greater to proteins than to lipoproteins of rat and human plasma; albumin was primarily responsible for protein binding. Higher total binding of each pyrethroid to human (∼90%) than to rat (∼80%) plasma resulted from higher protein binding in human plasma. This was attributable in part to the higher albumin/protein content of human plasma. Rat albumin exhibited lower pyrethroid binding capacity than did human albumin. The results of this investigation indicate that albumin and lipoproteins play a major role in binding and transport of pyrethroids in the systemic circulation of both rats and humans.

Crohn's Disease Is Associated with Decreased CYP3A4 and P-Glycoprotein Protein Expression

Cytochrome P450 (CYP) 3A4 and P-glycoprotein (P-gp) have broad substrate overlap and are involved in the metabolism and transport of nearly 50% of currently prescribed medications. In the intestine, CYP3A4 and P-gp are coexpressed in the enterocytes at the intestinal villous tip and act in a coordinated manner to limit drug and xenobiotic oral bioavailability prior to further metabolism and disposition in the liver. Crohn's disease (CD), a form of inflammatory bowel disease, introduces a transmural intestinal insult that disrupts the intestinal barrier function; it therefore has the potential to affect intestinal drug metabolism and transport. We hypothesized that individuals with CD have reduced intestinal expression of CYP3A4 and P-gp. We obtained intestinal biopsy samples from individuals with and without CD and quantified the expression of CYP3A4 and P-gp. When we carried out Western analysis for protein expression, we observed a significant reduction in ileal (45% decrease) and colonic (78% decrease) CYP3A4 protein expression in subjects with CD compared with those without. Similarly, an 85% reduction in colonic P-gp protein expression was seen in the CD patients. Our data highlight important and novel findings pertaining to CD-associated changes to the intestinal expression of CYP3A4 and P-gp that are of relevance to better predict substrate drug dosing for patients with CD.

Effect of hepatic impairment on the pharmacokinetics of vilaprisan: An open-label, single-dose, parallel-group study

Aims

The study objective was to evaluate the pharmacokinetics of the selective progesterone receptor modulator vilaprisan in participants with hepatic impairment. Additionally, the safety and tolerability of vilaprisan were investigated.

Methods

In this phase 1, open‐label, nonrandomised, parallel‐group, pharmacokinetic study, men and women with mild or moderate hepatic impairment (Child–Pugh grade A or B) and control participants with normal hepatic function matched by age, weight and sex received a single oral 2 mg dose of vilaprisan. Key pharmacokinetic parameters, relationships between parameters and safety outcomes were measured.

Results

Thirty‐six participants completed the study: 9 with mild hepatic impairment, 9 with moderate hepatic impairment and 18 matched control participants with normal hepatic function. Vilaprisan reached maximum plasma concentrations after 1–2 hours. Unbound vilaprisan exposure was 1.44‐fold higher for participants with mild hepatic impairment vs controls (90% confidence interval: 0.91–2.26), and 1.74‐fold higher for participants with moderate impairment vs controls (90% confidence interval: 1.09–2.78). The maximum observed unbound peak concentrations were similar for participants with hepatic impairment and matched controls. Vilaprisan 2 mg was well tolerated and the incidence of treatment‐emergent adverse events was similar across cohorts.

Conclusion

Only mild increases of <1.75‐fold in exposure were observed in participants with mild or moderate hepatic impairment compared with control participants. No safety concern was identified. These data, alongside the excellent safety profile observed in phase 1 and 2 studies, do not indicate that a dose adjustment would be required in patients with mild or moderate hepatic impairment.

The optimization of methadone dosing whilst treating with rifampicin: A pharmacokinetic modeling study

BACKGROUND

The use of oral methadone in opioid substitution treatment (OST) for the management of opioid use disorder is established clinical practice. Confounding treatment is the increased risks of contracting Mycobacterium tuberculosis, the mainstay treatment of which incorporates the potent CYP 2B6 inducer rifampicin.

METHODS

This study applied pharmacokinetic modelling using virtual clinical trials, to pharmacokinetically quantify the extent and impact of rifampicin-mediated drug-drug interactions (DDI) on methadone plasma concentrations. An R-methadone model was developed and validated against 11 retrospective clinical studies prior to use in all subsequent studies. The aims were to investigate: (i) the impact of the DDI on daily methadone doses of 60 mg, 90 mg and 120 mg; (ii) dose escalation during rifampicin and (iii) dose reduction following rifampicin cessation.

RESULTS

A dose increase to 160 mg daily during rifampicin treatment phases was required to maintain peak methadone plasma concentrations within a derived therapeutic window of 80-700 ng/mL. Dose escalation prior to rifampicin initiation was not required and resulted in an increase in subjects with supra-therapeutic concentrations. However, during rifampicin cessation, a dose reduction of 10 mg every 2 days commencing prior to rifampicin cessation, ensured that most patients possessed a peak methadone plasma concentration within an optimal therapeutic window.

IMPLICATIONS

Rifampicin significantly alters methadone plasma concentrations and necessitates dose adjustments. Daily doses of almost double those used perhaps more commonly in clinical practice are required for optimal plasma concentration and careful consideration of dose reduction strategies would be required during the deinduction phase.

2018 Korean Liver Cancer Association-National Cancer Center Korea Practice Guidelines for the Management of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer globally and the fourth most common cancer in men in Korea, where the prevalence of chronic hepatitis B infection is high in middle-aged and elderly patients. These practice guidelines will provide useful and constructive advice for the clinical management of patients with HCC. A total of 44 experts in hepatology, oncology, surgery, radiology, and radiation oncology in the Korean Liver Cancer Association-National Cancer Center Korea Practice Guideline Revision Committee revised the 2014 Korean guidelines and developed new recommendations that integrate the most up-to-date research findings and expert opinions.

Drug-Induced Acute-on-Chronic Liver Failure in Asian Patients

OBJECTIVES

Acute insults from viruses, infections, or alcohol are established causes of decompensation leading to acute-on-chronic liver failure (ACLF). Information regarding drugs as triggers of ACLF is lacking. We examined data regarding drugs producing ACLF and analyzed clinical features, laboratory characteristics, outcome, and predictors of mortality in patients with drug-induced ACLF.

METHODS

We identified drugs as precipitants of ACLF among prospective cohort of patients with ACLF from the Asian Pacific Association of Study of Liver (APASL) ACLF Research Consortium (AARC) database. Drugs were considered precipitants after exclusion of known causes together with a temporal association between exposure and decompensation. Outcome was defined as death from decompensation.

RESULTS

Of the 3,132 patients with ACLF, drugs were implicated as a cause in 329 (10.5%, mean age 47 years, 65% men) and other nondrug causes in 2,803 (89.5%) (group B). Complementary and alternative medications (71.7%) were the commonest insult, followed by combination antituberculosis therapy drugs (27.3%). Alcoholic liver disease (28.6%), cryptogenic liver disease (25.5%), and non-alcoholic steatohepatitis (NASH) (16.7%) were common causes of underlying liver diseases. Patients with drug-induced ACLF had jaundice (100%), ascites (88%), encephalopathy (46.5%), high Model for End-Stage Liver Disease (MELD) (30.2), and Child-Turcotte-Pugh score (12.1). The overall 90-day mortality was higher in drug-induced (46.5%) than in non-drug-induced ACLF (38.8%) (P = 0.007). The Cox regression model identified arterial lactate (P < 0.001) and total bilirubin (P = 0.008) as predictors of mortality.

DISCUSSION

Drugs are important identifiable causes of ACLF in Asia-Pacific countries, predominantly from complementary and alternative medications, followed by antituberculosis drugs. Encephalopathy, bilirubin, blood urea, lactate, and international normalized ratio (INR) predict mortality in drug-induced ACLF.

Pharmacological pain management in patients with chronic hepatic disease

Abstract The liver has a central role in the pharmacokinetics (absorption, distribution, elimination, etc.) of drugs. With hepatic insufficiency, the metabolism of drugs decreases, which accumulates metabolically or toxic active products. Some medicines can aggravate a pre-existing liver disease. Medicines used in this group of patients (especially diuretics and centrally acting preparations) can often cause impaired renal function or hepatic encephalopathy. The general principles of assessment, pain management and analgesia should be prescribed taking into account the Word Health Organization (WHO) recommendations for these patients, with careful and frequent monitoring of patient progress during treatment administration. Key words: hepatotoxicity, hepatic dysfunction, cirrhosis, pain medication,

2018 Korean Liver Cancer Association-National Cancer Center Korea Practice Guidelines for the Management of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer globally and the fourth most common cancer in men in Korea, where the prevalence of chronic hepatitis B infection is high in middle-aged and elderly patients. These practice guidelines will provide useful and constructive advice for the clinical management of patients with HCC. A total of 44 experts in hepatology, oncology, surgery, radiology and radiation oncology in the Korean Liver Cancer Association-National Cancer Center Korea Practice Guideline Revision Committee revised the 2014 Korean guidelines and developed new recommendations that integrate the most up-to-date research findings and expert opinions.

Medicine use and medicine-related problems in patients with liver cirrhosis: a systematic review of quantitative and qualitative studies

PURPOSE

This review aimed to determine the prevalence, causes and risk factors of medicine-related problems (MRPs) in patients with liver cirrhosis.

METHODS

Eight online databases were searched up to 30 September 2018 with no start date. Appropriate Critical Appraisal Skills Programme tools were used to assess the quality of included studies.

RESULTS

An overall 16 quantitative and 11 qualitative studies were included in the review. Methodological quality of the included studies was variable. Mean frequency of MRPs reported in the quantitative studies ranged from 14 to 23.4%. The most frequent causes of MRPs included drug interactions, inappropriate dosing and use of contraindicated drugs. The qualitative analysis identified three themes: patient-related factors, healthcare professionals' related factors and stigma associated with liver cirrhosis.

CONCLUSION

MRPs were found to be prevalent in patients with liver cirrhosis. Factors contributing to MRPs in liver cirrhosis were not limited to medicines' effects and interactions but included healthcare systems and patients. Therefore, management of liver cirrhosis should not be limited to providing an effective medicine therapy and should take into account the patients' behaviour towards the condition.

A semiphysiological population pharmacokinetic model of agomelatine and its metabolites in Chinese healthy volunteers

AIMS

Agomelatine is an antidepressant for major depressive disorders. It undergoes extensive first-pass hepatic metabolism and displays irregular absorption profiles and large interindividual variability (IIV) and interoccasion variability of pharmacokinetics. The objective of this study was to characterize the complex pharmacokinetics of agomelatine and its metabolites in healthy subjects.

METHODS

Plasma concentration-time data of agomelatine and its metabolites were collected from a 4-period, cross-over bioequivalence study, in which 44 healthy subjects received 25 mg agomelatine tablets orally. Nonlinear mixed effects modelling was used to characterize the pharmacokinetics and variability of agomelatine and its metabolites. Deterministic simulations were carried out to investigate the influence of pathological changes due to liver disease on agomelatine pharmacokinetics.

RESULTS

A semiphysiological pharmacokinetic model with parallel first-order absorption and a well-stirred liver compartment adequately described the data. The estimated IIV and interoccasion variability of the intrinsic clearance of agomelatine were 130.8% and 28.5%, respectively. The IIV of the intrinsic clearance turned out to be the main cause of the variability of area under the curve-based agomelatine exposure. Simulations demonstrated that a reduction in intrinsic clearance or liver blood flow, and an increase in free drug fraction had a rather modest influence on agomelatine exposures (range: -50 to 200%). Portosystemic shunting, however, substantially elevated agomelatine exposure by 12.6-109.1-fold.

CONCLUSIONS

A semiphysiological pharmacokinetic model incorporating first-pass hepatic extraction was developed for agomelatine and its main metabolites. The portosystemic shunting associated with liver disease might lead to significant alterations of agomelatine pharmacokinetics, and lead to substantially increased exposure.

Population pharmacokinetics of primaquine and the effect of hepatic and renal dysfunction: An exploratory approach

OBJECTIVES

We attempted to develop a population pharmacokinetic model for primaquine (PQ) and evaluate the effect of renal and hepatic dysfunction on PQ pharmacokinetics.

MATERIALS AND METHODS

The data were collected from a prospective, nonrandomized clinical study in healthy volunteers and patients with mild-moderate hepatic dysfunction and renal dysfunction. Model development was conducted using NONMEM^® software, and parameter estimation was conducted using first-order conditional estimation with interaction method.

RESULTS

Final data included a total of 53 study participants (13 healthy individuals, 12 with mild hepatic dysfunction, 6 with moderate hepatic dysfunction, and 22 with renal dysfunction) with 458 concentrations records. Absorption rate constant (Ka) was constrained to be higher than elimination rate constant to avoid flip-flop situation. Mild hepatic dysfunction was a significant covariate on volume of distribution, and it is approximately three folds higher compared to other subjects. Fixed effects parameter estimates of the final model - absorption rate constant (Ka), volume of distribution (V), and clearance (CL) - were 0.95/h, 498 L, and 39 L/h, respectively. Between-subject variability estimates (% CV) on Ka, V, and CL were 77, 66, and 65, respectively. Residual error was modeled as combination error model with the parameter estimates for proportion error 12% CV and additive error (standard deviation) 1.5 ng/ml.

CONCLUSION

Population pharmacokinetic modeling showed that the volume of distribution of PQ in subjects with moderate hepatic dysfunction increases approximately three folds resulting in a significantly lower plasma concentration.

Pharmacokinetics of the Investigational Aurora A Kinase Inhibitor Alisertib in Adult Patients With Advanced Solid Tumors or Relapsed/Refractory Lymphoma With Varying Degrees of Hepatic Dysfunction

This clinical trial was designed to evaluate the effect of moderate or severe hepatic impairment on the single-dose pharmacokinetics (PK) of the investigational anticancer agent, alisertib, in adult patients with advanced solid tumors or lymphoma. Patients with normal hepatic function (total bilirubin and alanine transaminase [ALT] ≤ upper limit of normal [ULN]), moderate hepatic impairment (1.5 × ULN < total bilirubin ≤ 3 × ULN, with any ALT) or severe hepatic impairment (total bilirubin > 3 × ULN, with any ALT), received a single 50-mg oral dose of alisertib. Blood samples for PK were collected up to 168 hours postdose. Predose samples were also used to assess alisertib plasma protein binding. Patients could continue to receive alisertib for 7 days in 21-day cycles (50, 30, or 10 mg twice daily for normal hepatic function, moderate hepatic impairment, and severe hepatic impairment, respectively). Alisertib was approximately 99% protein bound in all hepatic function groups. Alisertib exposure was similar in moderate and severe hepatic impairment groups, but higher than the normal hepatic function group. The geometric least-squares mean ratios (90% confidence intervals) for unbound alisertib area under the curve extrapolated to infinity for moderate/severe impairment groups versus the normal hepatic function group was 254% (184%, 353%). Patients with moderate or severe hepatic impairment have approximately 150% higher unbound alisertib exposures compared with patients with normal hepatic function. An approximately 60% reduction of the starting dose of alisertib in patients with moderate/severe hepatic impairment is recommended based on pharmacokinetic considerations.

Midazolam: Safety of use in palliative care: A systematic critical review

PURPOSE

The undesired effects of midazolam can be life-threatening. This paper delineates the findings related to the pharmacokinetics, adverse effects and drug-drug interactions as well as associated therapeutic implications for safe midazolam use.

METHODS

A systematic review of literature was conducted.

RESULTS

The pharmacokinetics of midazolam depends on hepatic and renal functions, fat tissue mass, route and duration of administration, as well as potential drug-drug interactions. Palliative care patients constitute a high-risk group prone to side effects of drugs, due to polytherapy and multi-organ failure.

CONCLUSION

Midazolam is one of three most frequently administered drugs in palliative care. The indications for its use include anxiety, dyspnea, seizures, vomiting refractory to treatment, agitation, myoclonus, status epilepticus, restlessness, delirium, pruritus, hiccups, insomnia, analgosedation, palliative sedation and preventing or counteracting undesired effects of ketamine.

Changes of drug pharmacokinetics mediated by downregulation of kidney organic cation transporters Mate1 and Oct2 in a rat model of hyperuricemia

The effects of hyperuricemia on the expression of kidney drug transporters and on the pharmacokinetics of several substrate drugs were examined. We first established a rat model of hyperuricemia without marked symptoms of chronic kidney failure by 10-day co-administration of oxonic acid (uricase inhibitor) and adenine (biosynthetic precursor of uric acid). These hyperuricemic rats showed plasma uric acid concentrations of up to 6 mg/dL, which is similar to the serum uric acid level in hyperuricemic humans, with little change of inulin clearance. The mRNA levels of multidrug and toxin extrusion 1 (Mate1, Slc47a1), organic anion transporter 1 (Oat1, Slc22a6), organic cation transporter 2 (Oct2, Slc22a2), urate transporter 1 (Urat1, Slc22a12) and peptide transporter 1 (Pept1, Slc15a1) were significantly decreased in kidney of hyperuricemic rats. Since Oct2, Mate1 and Oat1 are important for renal drug elimination, we next investigated whether the pharmacokinetics of their substrates, metformin, cephalexin and creatinine, were altered. The plasma concentration of metformin was not affected, while its kidney tissue accumulation was significantly increased. The plasma concentration and kidney tissue accumulation of cephalexin and the plasma concentration of creatinine were also increased. Furthermore, the protein expression of kidney Mate1 was decreased in hyperuricemic rats. Accordingly, although multiple factors may influence renal handling of these drugs, these observations can be accounted for, at least in part, by downregulation of Mate1-mediated apical efflux from tubular cells and Oct2-mediated basolateral uptake. Our results suggest that hyperuricemia could alter the disposition of drugs that are substrates of Mate1 and/or Oct2.

Prediction of Ticagrelor and its Active Metabolite in Liver Cirrhosis Populations Using a Physiologically Based Pharmacokinetic Model Involving Pharmacodynamics

Ticagrelor, a P2Y₁₂ receptor antagonist, has been highly recommended for use in acute coronary syndrome. The major active metabolite (AM) is similar to the parent drug, which exhibits antiplatelet activity. The inhibition of platelet aggregation (IPA) is used as an assay to demonstrate the anticoagulant efficacy of ticagrelor. In this study, we developed a physiologically based pharmacokinetic (PBPK) model to predict the pharmacokinetics of ticagrelor and its AM and combined this model with a pharmacodynamics model to reflect potential pharmacodynamic alterations in liver cirrhosis populations. The simulated results obtained using the PBPK model were validated by fold error values, which were all smaller than 2. Comparisons of exposure in different classifications of liver cirrhosis indicated that exposure to ticagrelor increased significantly with an increase in the degree of cirrhosis severity, whereas exposure to AM was decreased. The total concentration of ticagrelor and AM was related to the IPA included in the Sigmoid E_max model. The PBPK model of ticagrelor and AM could predict the pharmacokinetics of all populations, and a combination of PD models was used to extrapolate for predicting unknown scenarios. Liver cirrhosis may result in prolonged IPA, depending on the severity degree of this disease. The combined PBPK model including IPA can reveal changes in pharmacokinetics and pharmacodynamics in populations affected by liver cirrhosis and indicate the risk potential.

Nutritional Status Differentially Alters Cytochrome P450 3A4 (CYP3A4) and Uridine 5'-Diphospho-Glucuronosyltransferase (UGT) Mediated Drug Metabolism: Effect of Short-Term Fasting and High Fat Diet on Midazolam Metabolism

BACKGROUND AND OBJECTIVES

Previous studies have shown that nutritional status can alter drug metabolism which may result in treatment failure or untoward side effects. This study assesses the effect of two nutritional conditions, short-term fasting, and a short-term high fat diet (HFD) on cytochrome P450 3A4 (CYP3A4) and uridine 5'-diphospho-glucuronosyltransferase (UGT) mediated drug metabolism by studying the pharmacokinetics of midazolam and its main metabolites.

METHODS

In a randomized-controlled cross-over trial, nine healthy subjects received a single intravenous administration of 0.015 mg/kg midazolam after: (1) an overnight fast (control); (2) 36 h of fasting; and (3) an overnight fast after 3 days of a HFD consisting of 500 ml of cream supplemented to their regular diet. Pharmacokinetic parameters were analyzed simultaneously using non-linear mixed-effects modeling.

RESULTS

Short-term fasting increased CYP3A4-mediated midazolam clearance by 12% (p < 0.01) and decreased UGT-mediated metabolism apparent 1-OH-midazolam clearance by 13% (p < 0.01) by decreasing the ratio of clearance and the fraction metabolite formed (ΔCL_1-OH-MDZ/f_1-OH-MDZ). Furthermore, short-term fasting decreased apparent clearance of 1-OH-midazolam-O-glucuronide (CL_{1-OH-MDZ-glucuronide}/(f_{1-OH-MDZ-glucuronide} × f_1-OH-MDZ)) by 20% (p < 0.01). The HFD did not affect systemic clearance of midazolam or metabolites.

CONCLUSIONS

Short-term fasting differentially alters midazolam metabolism by increasing CYP3A4-mediated metabolism but by decreasing UGT-mediated metabolism. In contrast, a short-term HFD did not affect systemic clearance of midazolam.

An update on the safety of prescribing opioids in pediatrics

INTRODUCTION

The opioid abuse epidemic and its toll on the adolescent population have heightened awareness for safer opioid prescribing practices in pediatric pain management. Opioids remain the mainstay of therapy for severe pain, although there is an emphasis on multimodal therapy. Areas covered: In this update, the authors present information on parenteral/oral opioids commonly used in pediatrics. Recommendations for opioid use in special circumstances including neonates and developmental pharmacokinetic concerns are discussed. Due to noticeable interindividual variability, pharmacogenomics may be important for tailoring pain regimens. In particular, the role of CYP2D6 phenotypes on opioid selection/dosing and clinical implications are discussed. A summary of adverse effects and opioid safety data, and the role of regulations, risk assessment, Centers for Disease Control and Prevention guidelines, follow-up, and monitoring for compliance in opioid prescribing, are detailed. Expert opinion: 'One size does not fit all' describes the need for public policies focused on pediatric pain and opioid use, as children are not 'little adults.' Clinical trials to evaluate pharmacokinetics-pharmacodynamics of opioids are currently lacking. Development of novel biased opioid agonists, clinical integration of genetics in informed decision-making, and emphasis on top-down approaches to pain management will be key to decrease opioid reliance.