ECG Evaluation as Part of the Clinical Pharmacology Strategy in the Development of New Drugs: A Review of Current Practices and Opportunities Based on Five Case Studies.

The International Conference on Harmonization (ICH) E14 document was revised in 2015 to allow concentration-corrected QT interval (C-QTc) analysis to be applied to data from early clinical pharmacology studies to exclude a small drug-induced effect on QTc. Provided sufficiently high concentrations of the drug are obtained in the first-in-human (FIH) study, this approach can be used to obviate the need for a designated thorough QT (TQT) study. The E14 revision has resulted in a steady reduction in the number of TQT studies and an increased use of FIH studies to evaluate electrocardiogram (ECG) effects of drugs in development. In this review, five examples from different sponsors are shared in which C-QTc analysis was performed on data from FIH studies. Case 1 illustrates a clearly negative C-QTc evaluation, despite observations of QTc prolongation at high concentrations in nonclinical studies. In case 2 C-QTc analysis of FIH data was performed prior to full pharmacokinetic characterization in patients, and the role of nonclinical assays in an integrated risk assessment is discussed. Case 3 illustrates a positive clinical C-QTc relationship, despite negative nonclinical assays. Case 4 demonstrates a strategy for characterizing the C-QTc relationship for a nonracemic therapy and formulation optimization, and case 5 highlights an approach to perform a preliminary C-QTc analysis early in development and postpone the definitive analysis until proof of efficacy is demonstrated. The strategy of collecting and storing ECG data from FIH studies to enable an informed decision on whether and when to apply C-QTc analysis to obviate the need for a TQT study is described.

Aripiprazole Lauroxil Dosing Regimens: Understanding Dosage Strengths and Injection Intervals.

Aripiprazole lauroxil (AL) is a long-acting atypical antipsychotic approved for the treatment of schizophrenia in adults. AL has five regimen options that offer three different injection intervals using four different dosage strengths. The relationship between dosage strength (milligram injected), injection interval (time between injection visits), and expected steady-state plasma aripiprazole concentrations may not be readily apparent. This article illustrates the relationship by providing visual scenarios of steady-state plasma aripiprazole concentrations for the five AL regimens. The efficacy of AL was originally demonstrated in a pivotal study of two AL regimens (approved as 441 mg monthly and 882 mg monthly). The three additional regimens (662 mg monthly, 882 mg every 6 weeks, and 1064 mg every 2 months) were approved based on pharmacokinetic bridging studies and population pharmacokinetic models. For this paper, expected steady-state concentrations for each AL regimen were derived from the published population pharmacokinetic models and compared using median values and ranges. The five labeled AL regimens differ in dosage strength and injection interval; however, model-simulated concentrations illustrate that each regimen produces steady-state plasma aripiprazole concentrations within the upper and lower bounds associated with known efficacy for AL 441 mg and 882 mg administered monthly. This visual presentation of the relationship between dosage strength of the AL injection, the interval between successive injections, and steady-state aripiprazole plasma concentrations may demonstrate for clinicians how dosage strength and injection interval can be considered in selecting the AL regimen option that best fits the clinical circumstances of the individual patient.

Population Pharmacokinetics of Olanzapine and Samidorphan When Administered in Combination in Healthy Subjects and Patients With Schizophrenia.

A combination of olanzapine and samidorphan was recently approved by the US Food and Drug Administration for the treatment of patients with schizophrenia or bipolar I disorder. Population pharmacokinetic models for olanzapine and samidorphan were developed using data from 11 clinical studies in healthy subjects or patients with schizophrenia. A 2-compartment disposition model with first-order absorption and elimination and a lag time for absorption adequately described concentration-time profiles of both olanzapine and samidorphan. Age, sex, race, smoking status, and body weight were identified as covariates that impacted the pharmacokinetics of olanzapine. A moderate effect of body weight on samidorphan pharmacokinetics was identified by the model but was not considered clinically meaningful. The effects of food, hepatic or renal impairment, and coadministration with rifampin on the pharmacokinetics of olanzapine and samidorphan, as estimated by the population pharmacokinetic analysis, were consistent with findings from dedicated clinical studies designed to evaluate these specific covariates of interest. Food intake did not have a clinically relevant effect on the pharmacokinetics of olanzapine or samidorphan. Consistent with the known metabolic pathways for olanzapine (primarily via uridine 5'-diphospho-glucuronosyltransferase-mediated direct glucuronidation and cytochrome P450 [CYP]-mediated oxidation) and for samidorphan (predominantly mediated by CYP3A4), coadministration of olanzapine and samidorphan with rifampin, a strong inducer of CYP3A4 and an inducer of uridine 5'-diphospho-glucuronosyltransferase enzymes, significantly decreased the systemic exposure of both olanzapine and samidorphan. Severe renal impairment or moderate hepatic impairment resulted in a modest increase in olanzapine and samidorphan exposure.

Combination of olanzapine and samidorphan has no clinically relevant effects on ECG parameters, including the QTc interval: Results from a phase 1 QT/QTc study.

BACKGROUND: OLZ/SAM is a combination of olanzapine, an atypical antipsychotic, and samidorphan, an opioid antagonist, and is in development for the treatment of schizophrenia and bipolar I disorder. OLZ/SAM is under development with the intent to provide the established antipsychotic efficacy of olanzapine while mitigating olanzapine-associated weight gain. This thorough QT study assessed the effects of therapeutic and supratherapeutic doses of OLZ/SAM on cardiac repolarization in patients with schizophrenia. METHODS: In this randomized, double-blind, placebo- and positive (moxifloxacin)-controlled, parallel-group study, 100 patients aged 18 to 60 years with stable schizophrenia were randomized 3:2 to the active arm and control arm. Subjects in the active arm received a therapeutic dose of 10/10 mg (10 mg olanzapine/10 mg samidorphan) on days 2-4, 20/20 mg on days 5-8, and a supratherapeutic dose of 30/30 mg (1.5 times and 3 times the maximum recommended daily dose of olanzapine and samidorphan, respectively) on days 9-13, and moxifloxacin-matched placebo on days 1 and 14. Subjects in the control arm received a single oral dose of moxifloxacin 400 mg and moxifloxacin-matched placebo on days 1 and 14 in a nested crossover fashion, along with OLZ/SAM-matched placebo on days 2-13. Serial electrocardiograms (ECGs) and simultaneous plasma drug concentrations were determined pre- and post-dose. The effects of OLZ/SAM on heart rate and ECG parameters (QT interval with Fridericia's correction [QTcF], PR and QRS interval, and T-wave morphology) were evaluated, and the primary endpoint was change from baseline in QTcF (ΔQTcF). The relationship between drug concentration and ΔQTcF (C-QTc) was evaluated using a linear mixed-effects model. Safety monitoring included adverse events reporting and clinical laboratory assessments. RESULTS: Based on primary analysis using C-QTc modeling, no clinically concerning QTc effect (ie, placebo-corrected ΔQTcF [ΔΔQTcF] ≥10 msec) was observed across the OLZ/SAM dose range tested (10/10 to 30/30 mg), up to olanzapine and samidorphan concentrations of approximately 110 and 160 ng/mL, respectively. The slope (90% confidence interval [CI]) of the C-QTc relationship was shallow and not significant for either olanzapine or samidorphan (0.03 [-0.01, 0.08] and 0.01 [-0.01, 0.04] msec per ng/mL, respectively). The predicted ΔΔQTcF (90% CI) was 2.33 (-2.72, 7.38) and 1.38 (-3.37, 6.12) msec at the observed geometric mean maximal concentration (Cmax) of olanzapine (62.6 ng/mL) and samidorphan (75.1 ng/mL) on day 13, respectively. The study's assay sensitivity was confirmed by the C-QTc relationship of moxifloxacin. OLZ/SAM was well tolerated at all doses; adverse events occurring in >5% of subjects treated with OLZ/SAM were somnolence, weight increased, nausea, and dizziness. CONCLUSIONS: This thorough QT study in patients with stable schizophrenia demonstrated that OLZ/SAM, in doses and plasma concentrations up to supratherapeutic levels, does not have a clinically relevant effect on ECG parameters, including QT/QTc prolongation.

Size matters: the importance of particle size in a newly developed injectable formulation for the treatment of schizophrenia.

One of the challenges with initiating long-acting injectable (LAI) antipsychotic regimens is achieving relevant drug levels quickly. After first injection of the LAI antipsychotic aripiprazole lauroxil (AL), the lag to reaching relevant plasma aripiprazole levels was initially addressed using supplemental oral aripiprazole for 21 days. A 1-day AL initiation regimen using a NanoCrystal® Dispersion formulation of AL (ALNCD; Aristada Initio®) combined with a single 30 mg dose of oral aripiprazole has been developed as an alternative approach. We compared the 1-day AL initiation regimen (ALNCD + 30 mg oral aripiprazole for 1 day) with the 21-day AL initiation regimen (AL + 15 mg/day of oral aripiprazole for 21 days) using kinetic modeling. Observed and modeled data demonstrate that the 1-day AL initiation regimen provides continuous aripiprazole exposure comparable to the 21-day AL initiation regimen. Each component of the 1-day AL initiation regimen (30 mg oral aripiprazole, ALNCD, and AL) contributes to aripiprazole plasma levels at different times, with oral aripiprazole predominating in the first week, then ALNCD and AL over time. In a double-blind, placebo-controlled, phase 1 study in patients with schizophrenia, the 1-day initiation regimen resulted in rapid achievement of relevant plasma aripiprazole levels comparable to those from the 21-day initiation regimen. Safety and tolerability of the 1-day regimen were consistent with the known profile of aripiprazole. Each part of the 1-day initiation regimen, together with AL, is necessary for continuous aripiprazole exposure from treatment initiation until the next regularly scheduled AL injection is administered.

Adjunctive Perampanel Oral Suspension in Pediatric Patients From ≥2 to <12 Years of Age With Epilepsy: Pharmacokinetics, Safety, Tolerability, and Efficacy.

Study 232, an open-label pilot study with an extension phase, evaluated the pharmacokinetics and preliminary safety/tolerability and efficacy of adjunctive perampanel oral suspension (≤0.18 mg/kg/d) in epilepsy patients aged ≥2 to <12 years. Patients were grouped into cohorts 1 (aged ≥7 to <12 years) and 2 (aged ≥2 to <7 years). The Core Study included pretreatment (≤2 weeks) and treatment phases (7-week titration; 4-week maintenance; 4-week follow-up [for those not entering the extension]). The extension phase consisted of 41-week maintenance and 4-week follow-up periods. Pharmacokinetic data were pooled with adolescent pharmacokinetic data from phase II/III studies. Population pharmacokinetic analysis showed that perampanel pharmacokinetics was independent of age, weight, or liver function, suggesting age- or weight-based dosing is not required and that the same dose can be given to adults and children to achieve exposures shown to be efficacious. Perampanel was well tolerated and efficacious for ≤52 weeks.

Pharmacokinetic/pharmacodynamic drug-drug interactions of avatrombopag when coadministered with dual or selective CYP2C9 and CYP3A interacting drugs.

AIMS: Avatrombopag, a thrombopoietin receptor agonist, is a substrate of cytochrome P450 (CYP) 2C9 and CYP3A. We assessed three drug-drug interactions of avatrombopag as a victim with dual or selective CYP2C9/3A inhibitors and inducers. METHODS: This was a three-part, open-label study. Forty-eight healthy subjects received single 20 mg doses of avatrombopag alone or with one of 3 CYP2C9/3A inhibitors or inducers: fluconazole 400 mg once daily for 16 days, itraconazole 200 mg twice daily on Day 1 and 200 mg once daily on Days 2-16, or rifampicin 600 mg once daily for 16 days. Pharmacokinetics, pharmacodynamics (platelet count) and safety of avatrombopag were evaluated. RESULTS: Coadministration of a single 20-mg dose of avatrombopag with fluconazole at steady-state resulted in 2.16-fold increase of AUC of avatrombopag, prolonged terminal elimination phase half-life (from 19.7 h to 39.9 h) and led to a clinically significant increase in maximum platelet count (1.66-fold). Itraconazole had a mild increase on both avatrombopag pharmacokinetics and pharmacodynamics compared to fluconazole. Coadministration of rifampicin caused a 0.5-fold decrease in AUC and shortened terminal elimination phase half-life (from 20.3 h to 9.84 h), but has no impact on maximum platelet count. Coadministration with interacting drugs was found to be generally safe and well-tolerated. CONCLUSIONS: The results from coadministration of fluconazole or itraconazole suggest that CYP2C9 plays a more predominant role in metabolic clearance of avatrombopag than CYP3A. To achieve comparable platelet count increases when avatrombopag is coadministered with CYP3A and CYP2C9 inhibitors, an adjustment in the dose or duration of treatment is recommended, while coadministration with strong inducers is not currently recommended.

Pharmacokinetics, Pharmacodynamics, Pharmacogenomics, Safety, and Tolerability of Avatrombopag in Healthy Japanese and White Subjects.

Avatrombopag, an orally administered, small-molecule thrombopoietin receptor (c-Mpl) agonist, is currently in clinical development for the potential treatment of severe thrombocytopenia in patients with chronic liver disease undergoing an elective procedure. The objectives of this study were to characterize and compare the pharmacokinetics (including the food effect) and pharmacodynamics (platelet count) of avatrombopag following single doses in Japanese and white subjects. Following single dosing under fasted and fed conditions, mean peak concentrations occurred at 5 to 8 hours and subsequently declined with a half-life of 16 to 18 hours in Japanese and white subjects. Administration with food did not alter the rate or extent of avatrombopag absorption but substantially reduced pharmacokinetic variability relative to the fasted state. CYP2C9 polymorphism (*2, *3) was associated with higher pharmacokinetic variability but not with any clinically important effect on variability in platelet response. Plasma exposures of avatrombopag increased in a dose-proportional manner over the dose range tested. After a single dose, platelet count increased in a dose-related manner, reaching a maximum by day 11 and returning to baseline levels by day 27. No clinically important differences were found when avatrombopag pharmacokinetics and pharmacodynamics were compared between Japanese and white subjects. Administration of avatrombopag was generally well tolerated.

Concentration-Response Modeling of ECG Data From Early-Phase Clinical Studies as an Alternative Clinical and Regulatory Approach to Assessing QT Risk - Experience From the Development Program of Lemborexant.

Lemborexant is a novel dual orexin receptor antagonist being developed to treat insomnia. Its potential to cause QT prolongation was evaluated using plasma concentration-response (CR) modeling applied to data from 2 multiple ascending-dose (MAD) studies. In the primary MAD study, placebo or lemborexant (2.5 to 75 mg) was administered for 14 consecutive nights. In another MAD study designed to "bridge" pharmacokinetic and safety data between Japanese and non-Japanese subjects (J-MAD), placebo or lemborexant (2.5, 10, or 25 mg) was administered for 14 consecutive nights. QT intervals were estimated using a high-precision measurement technique and evaluated using a linear mixed-effects CR model, for each study separately and for the pooled data set. When each study was analyzed separately, the slopes of the CR relationship were shallow and not statistically significant. In the pooled analysis, the slope of the CR relationship was -0.00002 milliseconds per ng/mL (90%CI, -0.01019 to 0.01014 milliseconds). The highest observed Cmax was 400 ng/mL, representing a margin 8-fold above exposures expected for the highest planned clinical dose. The model-predicted QTc effect at 400 ng/mL was 1.1 milliseconds (90%CI, -3.49 to 5.78 milliseconds). In neither the J-MAD study nor the pooled analysis was an effect of race identified. CR modeling of data from early-phase clinical studies, including plasma levels far exceeding those anticipated clinically, indicated that a QT effect >10 milliseconds could be excluded. Regulatory agreement with this methodology demonstrates the effectiveness of a CR modeling approach as an alternative to thorough QT studies.

Single- and Multiple-dose Pharmacokinetics of a Lorcaserin Extended-release Tablet.

PURPOSE: Lorcaserin is a serotonin 2C receptor agonist indicated for chronic weight management as an adjunct to diet and exercise. The initial approved formulation is a 10-mg, immediate-release (IR) tablet for administration BID. These studies investigated the single- and multiple-dose pharmacokinetic properties of a new, recently US Food and Drug Administration-approved, extended-release, 20-mg once-daily formulation. METHODS: We performed 2 separate 2-period, 2-sequence crossover studies in 36 healthy adults: a study comparing the IR formulation to the extended-release formulation under fasting conditions and a study comparing the extended-release formulation under fed and fasted conditions. FINDINGS: Compared with lorcaserin IR, the Tmax after a single dose of lorcaserin extended-release was greater (median, 12 vs 3 hours), and the Cmax was 26% lower (38.8 vs 52.3 ng/mL). AUC data were bioequivalent for the 2 formulations in both single- and multiple-dose regimens, confirming no formulation effect on lorcaserin bioavailability. In fasted and fed conditions, Tmax after a single dose was identical (median, 12 hours), but Cmax was approximately 45% higher in the fed state (mean, 38.5 ng/mL fasted vs 56.1 ng/mL fed). However, at steady state, Cmax and AUC were determined to be bioequivalent between the fasted and fed states, indicating no clinically relevant food effect on the pharmacokinetic properties of lorcaserin extended-release. The safety profile was consistent between the 2 formulations. IMPLICATIONS: Overall, the results indicate that lorcaserin extended-release is a suitable once-daily alternative to the approved IR BID formulation.

Effect of chronic renal insufficiency on hepatic and renal udp-glucuronyltransferases in rats.

Significant evidence exists regarding altered CYP450 enzymes in chronic renal insufficiency (CRI), although none exists for the phase II enzymes. The objective of this study was to investigate the effect of CRI on hepatic and renal UDP-glucuronyltransferase (UGT) enzymes. Three groups of rats were included: CRI induced by the 5/6th nephrectomy model, control, and control pair-fed (CPF) rats. UGT activities were determined in liver and kidney microsomes by the 3- and 17-glucuronidation of beta-estradiol (E2-3G and E2-17G), glucuronidation of 4-methylumbelliferone (4-MUG), and 3-glucuronidation of morphine (M3G). UGT isoforms responsible for these catalytic activities were screened using recombinant rat UGT1A1, UGT1A2, UGT1A3, UGT1A7, UGT2B2, UGT2B3, and UGT2B8. UGT protein levels were examined by Western blot analysis using polyclonal antibodies. There was no significant difference between CRI and CPF rats in hepatic and/or renal E2-3G (UGT1A1), E2-17G (UGT2B3), 4-MUG (UGT1A6), and M3G (UGT2B1) formation. Formation of E2-17G and 4-MUG in the liver and E2-3G and 4-MUG in the kidney was significantly reduced (p < 0.05) in CPF and CRI rats compared with control rats. The down-regulated glucuronidation activities were accompanied by corresponding reductions in protein content of specific UGT isoforms. These results suggest that CRI does not seem to influence the protein levels or catalytic activity of most of the major hepatic or renal UGT enzymes. The observed down-regulation of hepatic and renal UGTs in CRI and CPF rats could be caused by restricted food intake in these groups of rats.

Down-regulation of hepatic CYP3A in chronic renal insufficiency.

PURPOSE: The objective of this study was to investigate the mechanisms underlying the decrease in hepatic clearance of some drugs metabolized by CYP450 enzymes in chronic renal insufficiency (CRI). METHODS: CRI was induced in male Sprague-Dawley rats (n = 7) by the remnant kidney model (RKM); control animals (C) (n = 12) underwent sham surgery, of which n = 6 rats were pair-fed (CPF) with CRI rats and others (n = 6) had free access to food. Serum creatinine (Scr) and urea nitrogen (SUN) were monitored every 2 weeks. On day 36, livers were isolated, and microsomes were prepared. Catalytic activities were measured through O-demethylation (CYP2D) and N-demethylation of dextromethorphan (CYP3A) and O-deethylation of 7-ethoxyresorufin (CYP1A2). CYP450 protein and mRNA levels were also measured. RESULTS: Compared with CPF, Scr and SUN levels in CRI rats were increased twofold (p < 0.01) and 2.5-fold (p < 0.01), respectively. No effect on CYP1A2 and CYP2D activities, mRNA, or protein levels was observed between the groups. There was a reduction (41.8 +/- 20%, p < 0.01) in CYP3A activity, mRNA (p < 0.05), and protein levels (p < 0.05) in CRI rats compared to CPF. CONCLUSIONS: CRI induced by RKM does not have an effect on hepatic CYP1A2 and CYP2D enzymes but does reduce CYP3A activity, probably through down-regulation of CYP3A2.

Development of a rapid and sensitive high-performance liquid chromatographic method to determine CYP2D6 phenotype in human liver microsomes.

Dextromethorphan is a probe substrate to determine CYP2D6 phenotype. The conversion of dextromethorphan to dextrorphan by CYP2D6 accounts for approximately 60% of total metabolism. Most analytical methods utilize complicated labor- and time-intensive sample processing methods with several liquid-liquid extraction (LLE) steps. Our goal was to develop a non-LLE based rapid and sensitive HPLC method, to measure dextromethorphan metabolism in human liver microsomes. A solid-phase filtration based reverse-phase HPLC method with fluorescence detection was developed and validated. Human liver (n = 6) microsomal incubations were carried out with dextromethorphan, under optimum conditions. The analytes were separated by one-step centrifugal filtration with Nanosep separation units. The filtrate was injected ( 50 microL) into a Waters Alliance 2690 HPLC system. Metabolic incubations were also conducted to determine levels using LLE for comparisons. The Nanosep separation step reduced the extraction time from 3h to 40 min. The limit of quantitation was 23.8 nM (9.7 ng/mL), recovery was approximately 98%, the mean precision values were <10% RSD for the controls (80, 320 and 640 nM) and mean percentage error was <5%. Michaelis-Menten parameters were determined to distinguish CYP2D6 phenotypes. A rapid and sensitive HPLC method is reported, which may be suitable for automation and allows phenotyping of human liver microsomes.