Therapeutic Plasma Concentrations Research Articles

The Potential Mechanisms behind Loperamide-Induced Cardiac Arrhythmias Associated with Human Abuse and Extreme Overdose.

Loperamide has been a safe and effective treatment for diarrhea for many years. However, many cases of cardiotoxicity with intentional abuse of loperamide ingestion have recently been reported. We evaluated loperamide in in vitro and in vivo cardiac safety models to understand the mechanisms for this cardiotoxicity. Loperamide slowed conduction (QRS-duration) starting at 0.3 µM [~1200-fold (×) its human Free Therapeutic Plasma Concentration; FTPC] and reduced the QT-interval and caused cardiac arrhythmias starting at 3 µM (~12,000× FTPC) in an isolated rabbit ventricular-wedge model. Loperamide also slowed conduction and elicited Type II/III A-V block in anesthetized guinea pigs at overdose exposures of 879× and 3802× FTPC. In ion-channel studies, loperamide inhibited hERG (IKr), INa, and ICa currents with IC50 values of 0.390 µM, 0.526 µM, and 4.091 µM, respectively (i.e., >1560× FTPC). Additionally, in silico trials in human ventricular action potential models based on these IC50s confirmed that loperamide has large safety margins at therapeutic exposures (≤600× FTPC) and confirmed repolarization abnormalities in the case of extreme doses of loperamide. The studies confirmed the large safety margin for the therapeutic use of loperamide but revealed that at the extreme exposure levels observed in human overdose, loperamide can cause a combination of conduction slowing and alterations in repolarization time, resulting in cardiac proarrhythmia. Loperamide's inhibition of the INa channel and hERG-mediated IKr are the most likely basis for this cardiac electrophysiological toxicity at overdose exposures. The cardiac toxic effects of loperamide at the overdoses could be aggravated by co-medication with other drug(s) causing ion channel inhibition.

Effects of carbamazepine on the central nervous system of zebrafish at human therapeutic plasma levels

The fish plasma model (FPM) facilitated the environmental risk assessment of human drugs by using existing data on human therapeutic plasma concentrations (HTPCs) and predicted fish plasma concentrations (FPCs). However, studies on carbamazepine (CMZ) with both the mode of action (MOA) based biological effects at molecular level (such as neurotransmitter and gene level) and measured FPCs are lacking. Bioconcentration of CMZ in adult zebrafish demonstrated that the FPM underestimated the bioconcentration factors (BCFs) in plasma at environmental CMZ exposure concentrations (1-100μg/L). CMZ significantly increased Glu and GABA, decreased ACh and AChE as well as inhibited the transcription levels of gabra1, grin1b, grin2b, gad1b, and abat when the actual FPCs were in the ranges of 1/1000 HTPC to HTPC. It is the first read-across study of CMZ integrating MOA-based biological effects at molecular level and FPCs. This study facilitates model performance against a range of different drug classes.

Inadequate Lopinavir Concentrations With Modified 8-Hourly Lopinavir/Ritonavir 4:1 Dosing During Rifampicin-based Tuberculosis Treatment in Children Living With HIV.

Lopinavir/ritonavir plasma concentrations are profoundly reduced when co-administered with rifampicin. Super-boosting of lopinavir/ritonavir is limited by nonavailability of single-entity ritonavir, while double-dosing of co-formulated lopinavir/ritonavir given twice-daily produces suboptimal lopinavir concentrations in young children. We evaluated whether increased daily dosing with modified 8-hourly lopinavir/ritonavir 4:1 would maintain therapeutic plasma concentrations of lopinavir in children living with HIV receiving rifampicin-based antituberculosis treatment. Children with HIV/tuberculosis coinfection weighing 3.0 to 19.9 kg, on rifampicin-based antituberculosis treatment were commenced or switched to 8-hourly liquid lopinavir/ritonavir 4:1 with increased daily dosing using weight-band dosing approach. A standard twice-daily dosing of lopinavir/ritonavir was resumed 2 weeks after completing antituberculosis treatment. Plasma sampling was conducted during and 4 weeks after completing antituberculosis treatment. Of 20 children enrolled; 15, 1-7 years old, had pharmacokinetics sampling available for analysis. Lopinavir concentrations (median [range]) on 8-hourly lopinavir/ritonavir co-administered with rifampicin (n = 15; area under the curve 0-24 55.32 mg/h/L [0.30-398.7 mg/h/L]; C max 3.04 mg/L [0.03-18.6 mg/L]; C 8hr 0.90 mg/L [0.01-13.7 mg/L]) were lower than on standard dosing without rifampicin (n = 12; area under the curve 24 121.63 mg/h/L [2.56-487.3 mg/h/L]; C max 9.45 mg/L [0.39-26.4 mg/L]; C 12hr 3.03 mg/L [0.01-17.7 mg/L]). During and after rifampicin cotreatment, only 7 of 15 (44.7%) and 8 of 12 (66.7%) children, respectively, achieved targeted pre-dose lopinavir concentrations ≥1mg/L. Modified 8-hourly dosing of lopinavir/ritonavir failed to achieve adequate lopinavir concentrations with concurrent antituberculosis treatment. The subtherapeutic lopinavir exposures on standard dosing after antituberculosis treatment are of concern and requires further evaluation.

OPTIMAL PLASMA CONCENTRATION OF THROMBOMODULIN ALFA TO TREAT SEPSIS-INDUCED DISSEMINATED INTRAVASCULAR COAGULATION.

Thrombomodulin alfa (TM alfa) has been shown effective for treatment of disseminated intravascular coagulation (DIC) associated with sepsis, although the optimal therapeutic plasma concentration has not been clarified. In the present study, the plasma trough concentration of TM alfa in septic patients with DIC was determined, then the cutoff value for that concentration showing influence on treatment outcome was calculated using a receiver operating characteristic curve. With a cutoff value of 1,010, the area under the curve of the receiver operating characteristic was 0.669 (95% confidence interval, 0.530-0.808), with sensitivity of 0.458 and specificity of 0.882. To evaluate its accuracy, patients were divided into those above or below the cutoff value, and 90-day survival rates were compared. The above-cutoff group showed a significantly higher 90-day survival rate (91.7%) as compared with the below-cutoff group (63.4%) ( P = 0.017), with a hazard ratio of 0.199 (95% confidence interval, 0.045-0.871). Interestingly, the incidence of hemorrhagic adverse effects was not significantly different between the groups. Based on these results, the recommended plasma trough concentration of TM alfa for treatment of septic DIC is 1,010 ng/mL, which should minimize the risk of severe bleeding while maximizing the therapeutic effect.

Pharmacokinetics and Safety of Sulfamethoxazole-Trimethoprim After Oral Administration of Single and Multiple Doses to Rhode Island Red Chickens (Gallus gallus domesticus).

Sulfamethoxazole-trimethoprim (SMZ-TMP), a commonly prescribed antibiotic for backyard hens, is neither Food and Drug Administration approved nor prohibited in laying hens in the United States. The aim of this study was to determine whether plasma concentrations above targeted minimum inhibitory concentration breakpoint values for Enterobacteriaceae could be achieved with oral dosing. Five Rhode Island red hens (Gallus gallus domesticus) were administered a single dose of 96 mg/kg SMZ-TMP (80 mg/kg SMZ and 16 mg/kg TMP) IV followed by the same dose orally after a washout period. Following oral dosing, mean SMZ concentrations exceeded the target breakpoint for approximately 12 hours; however, TMP only briefly exceeded the target breakpoint. Bioavailability was 60.5% for SMZ and 82.0% for TMP. Ten naïve birds were allocated into control (n = 4) and treatment (n = 6) groups for a 7-day multi-dose study. Treatment birds received an oral suspension dosed at 16 mg/kg TMP and 80 mg/kg SMZ every 48 hours (on days 1, 3, 5, and 7); TMP tablets were additionally dosed at 25 mg/bird on days 1, 3, 5, and 7, and 50 mg/bird on days 2, 4, and 6. Plasma SMZ-TMP concentrations were measured on a multiple time interval by ultraperformance liquid chromatography-mass spectrometry, and pharmacokinetic analyses were performed using a noncompartmental model. No accumulation for either drug was noted following repeated dosing, and no statistical differences in biochemical values, packed cell volumes, or weight were found between pre- and posttreatment in either the treatment or control groups. Sulfamethoxazole (80 mg/kg q48h PO) and TMP (24.1-28.0 mg/kg q24h PO) maintained therapeutic plasma concentrations at or exceeding the minimum inhibitory concentration breakpoint of Enterobacteriaceae for 72 and 24 hours for TMP and SMZ, respectively, without evidence of adverse effects or drug accumulation. Further studies are needed to refine this dosage regimen and evaluate adverse effects in ill birds.

Short-course, high-dose primaquine regimens for the treatment of liver-stage vivax malaria in children

ObjectivesTo assess the pharmacokinetics, safety, and tolerability of two high-dose, short-course primaquine (PQ) regimens compared with standard care in children with Plasmodium vivax infections. MethodsWe performed an open-label pediatric dose-escalation study in Madang, Papua New Guinea (Clinicaltrials.gov NCT02364583). Children aged 5-10 years with confirmed blood-stage vivax malaria and normal glucose-6-phosphate dehydrogenase activity were allocated to one of three PQ treatment regimens in a stepwise design (group A: 0.5 mg/kg once daily for 14 days, group B: 1 mg/kg once daily for 7 days, and group C: 1 mg/kg twice daily for 3.5-days). The study assessments were completed at each treatment time point and fortnightly for 2 months after PQ administration. ResultsBetween August 2013 and May 2018, 707 children were screened and 73 met the eligibility criteria (15, 40, and 16 allocated to groups A, B, and C, respectively). All children completed the study procedures. The three regimens were safe and generally well tolerated. The pharmacokinetic analysis indicated that an additional weight adjustment of the conventionally recommended milligram per kilogram PQ doses is not necessary to ensure the therapeutic plasma concentrations in pediatric patients. ConclusionsA novel, ultra-short 3.5-day PQ regimen has potential benefits for improving the treatment outcomes in children with vivax malaria that warrants further investigation in a large-scale clinical trial.

Effectiveness of Genotype-Specific Tricyclic Antidepressant Dosing in Patients With Major Depressive Disorder

Evidence of the clinical benefit of pharmacogenetics-informed treatment (PIT) with antidepressants is still limited. Especially for tricyclic antidepressants (TCAs), pharmacogenetics may be of interest because therapeutic plasma concentrations are well defined, identification of optimal dosing can be time consuming, and treatment is frequently accompanied by adverse effects. To determine whether PIT results in faster attainment of therapeutic TCA plasma concentrations compared with usual treatment in patients with unipolar major depressive disorder (MDD). This randomized clinical trial compared PIT with usual treatment among 111 patients at 4 centers in the Netherlands. Patients were treated with the TCAs nortriptyline, clomipramine, or imipramine, with clinical follow-up of 7 weeks. Patients were enrolled from June 1, 2018, to January 1, 2022. At inclusion, patients had unipolar nonpsychotic MDD (with a score of ≥19 on the 17-item Hamilton Rating Scale for Depression [HAMD-17]), were aged 18 to 65 years, and were eligible for TCA treatment. Main exclusion criteria were a bipolar or psychotic disorder, substance use disorder, pregnancy, interacting comedications, and concurrent use of psychotropic medications. In the PIT group, the initial TCA dosage was based on CYP2D6 and CYP2C19 genotypes. The control group received usual treatment, which comprised the standard initial TCA dosage. The primary outcome was days until attainment of a therapeutic TCA plasma concentration. Secondary outcomes were severity of depressive symptoms (measured by HAMD-17 scores) and frequency and severity of adverse effects (measured by Frequency, Intensity, and Burden of Side Effects Rating scores). Of 125 patients randomized, 111 (mean [SD] age, 41.7 [13.3] years; 69 [62.2%] female) were included in the analysis; of those, 56 were in the PIT group and 55 were in the control group. The PIT group reached therapeutic concentrations faster than the control group (mean [SD], 17.3 [11.2] vs 22.0 [10.2] days; Kaplan-Meier χ21 = 4.30; P = .04). No significant difference in reduction of depressive symptoms was observed. Linear mixed-model analyses showed that the interaction between group and time differed for the frequency (F6,125 = 4.03; P = .001), severity (F6,114 = 3.10; P = .008), and burden (F6,112 = 2.56; P = .02) of adverse effects, suggesting that adverse effects decreased relatively more for those receiving PIT. In this randomized clinical trial, PIT resulted in faster attainment of therapeutic TCA concentrations, with potentially fewer and less severe adverse effects. No effect on depressive symptoms was observed. These findings indicate that pharmacogenetics-informed dosing of TCAs can be safely applied and may be useful in personalizing treatment for patients with MDD. ClinicalTrials.gov Identifier: NCT03548675.

Integrated safety summary from Phase 3 clinical trials of IPX203, an extended-release carbidopa-levodopa formulation, in Parkinson disease (P1-11.006)

Integrated safety summary from Phase 3 clinical trials of IPX203, an extended-release carbidopa-levodopa formulation, in Parkinson disease (P1-11.006)

Long-term Safety and Efficacy of IPX203 in Parkinson’s Disease Patients with Motor Fluctuations: A 9-Month Open-label Extension Trial (S32.006)

Long-term Safety and Efficacy of IPX203 in Parkinson’s Disease Patients with Motor Fluctuations: A 9-Month Open-label Extension Trial (S32.006)

Preclinical Pharmacology of Solriamfetol: Potential Mechanisms for Wake Promotion

AbstractIntroductionSolriamfetol is a wake-promoting agent (WPA) approved for the treatment of excessive daytime sleepiness associated with narcolepsy and obstructive sleep apnea. The wake-promoting mechanism of solriamfetol may result from dopamine and norepinephrine reuptake inhibition. Preclinical pharmacology studies were conducted to further elucidate the molecular targets activated by solriamfetol and compare them to that of known WPAs and traditional stimulants.MethodsIn vitro binding and functional studies were conducted in a panel of cell lines or membrane preparations expressing transmembrane receptors and monoamine transporters to measure the activity of solriamfetol, comparator WPAs, and traditional stimulants. Electrophysiology studies were conducted in slice preparations from mouse ventral tegmental area (VTA). Studies to measure locomotor activity and wake-promoting effects were conducted in mice.ResultsIn vitro functional studies showed agonist activity of solriamfetol at human, mouse, and rat TAAR1 receptors. hTAAR1 EC50 values (10–16 μM) were within the clinically observed therapeutic solriamfetol plasma concentration range and overlapped with the observed DAT/NET inhibitory potencies of solriamfetol in vitro. TAAR1 agonist activity was unique to solriamfetol; neither the WPA modafinil nor the DAT/NET inhibitor bupropion had TAAR1 agonist activity. Solriamfetol (1–10 μM) dose-dependently inhibited the firing frequency of dopaminergic VTA neurons in mouse brain slices, similar to known TAAR1 agonists; however, these effects were inhibited by a D2 antagonist, suggesting a DAT-mediated effect. Unlike traditional stimulants, solriamfetol did not increase locomotor activity in naive mice, but inhibited the increase in locomotor activity in DAT knockout mice.ConclusionsPreclinical studies have identified agonist activity at the TAAR1 receptor and, possibly, lower potency agonist activity at 5-HT1A receptors as potential pharmacological targets for solriamfetol, in addition to its activity as a DAT/NET inhibitor. Given the current understanding of TAAR1 agonists as modulators of monoamine transmission with potential wake-promoting effects in multiple preclinical species, agonist activity at the hTAAR1 receptor may represent an additional pharmacological target underlying the wake-promoting effects for solriamfetol, in addition to its DNRI activity.FundingAxsome Therapeutics, Jazz Pharmaceuticals

FDA approved drugs with antiviral activity against SARS-CoV-2: From structure-based repurposing to host-specific mechanisms

The continuing heavy toll of the COVID-19 pandemic necessitates development of therapeutic options. We adopted structure-based drug repurposing to screen FDA-approved drugs for inhibitory effects against main protease enzyme (Mpro) substrate-binding pocket of SARS-CoV-2 for non-covalent and covalent binding. Top candidates were screened against infectious SARS-CoV-2 in a cell-based viral replication assay. Promising candidates included atovaquone, mebendazole, ouabain, dronedarone, and entacapone, although atovaquone and mebendazole were the only two candidates with IC50s that fall within their therapeutic plasma concentration. Additionally, we performed Mpro assays on the top hits, which demonstrated inhibition of Mpro by dronedarone (IC50 18 µM), mebendazole (IC50 19 µM) and entacapone (IC50 9 µM). Atovaquone showed only modest Mpro inhibition, and thus we explored other potential mechanisms. Although atovaquone is Dihydroorotate dehydrogenase (DHODH) inhibitor, we did not observe inhibition of DHODH at the respective SARS-CoV-2 IC50. Metabolomic profiling of atovaquone treated cells showed dysregulation of purine metabolism pathway metabolite, where ecto-5′-nucleotidase (NT5E) was downregulated by atovaquone at concentrations equivalent to its antiviral IC50. Atovaquone and mebendazole are promising candidates with SARS-CoV-2 antiviral activity. While mebendazole does appear to target Mpro, atovaquone may inhibit SARS-CoV-2 viral replication by targeting host purine metabolism.

ABT-333 (Dasabuvir) Increases Action Potential Duration and Provokes Early Afterdepolarizations in Canine Left Ventricular Cells via Inhibition of IKr.

ABT-333 (dasabuvir) is an antiviral agent used in hepatitis C treatment. The molecule, similarly to some inhibitors of hERG channels, responsible for the delayed rectifier potassium current (IKr), contains the methanesulfonamide group. Reduced IKr current leads to long QT syndrome and early afterdepolarizations (EADs), therefore potentially causing life-threatening arrhythmias and sudden cardiac death. Our goal was to investigate the acute effects of ABT-333 in enzymatically isolated canine left ventricular myocardial cells. Action potentials (APs) and ion currents were recorded with a sharp microelectrode technique and whole-cell patch clamp, respectively. Application of 1 μM ABT-333 prolonged the AP in a reversible manner. The maximal rates of phases 0 and 1 were irreversibly decreased. Higher ABT-333 concentrations caused larger AP prolongation, elevation of the early plateau potential, and reduction of maximal rates of phases 0, 1, and 3. EADs occurred in some cells in 3-30 μM ABT-333 concentrations. The 10 μM ABT-333-sensitive current, recorded with AP voltage clamp, contained a late outward component corresponding to IKr and an early outward one corresponding to transient outward potassium current (Ito). ABT-333 reduced hERG-channel-mediated ion current in a concentration-dependent, partially reversible manner with a half-inhibitory concentration of 3.2 μM. As the therapeutic plasma concentration of ABT-333 can reach the low μM range, ABT-333 application carries a risk of cardiac side effects especially in case of coadministration with strong inhibitors of CYP2C8.

Pharmacogenetics to Personalize Dosing of Tricyclic Antidepressants in Major Depressive Disorder: A Randomized Clinical Trial (PITA study)

IntroductionTricyclic antidepressants (TCAs) have an important role in pharmacotherapy of Major Depressive Disorder (MDD). TCA dosing is aimed at achieving a concentration in the therapeutic window. Due to inter-individual differences in activity of Cytochrome P450 (CYP) 2D6 and 2C19, (enzymes involved in TCA metabolism) patients require an individualized dose. Currently, finding of a suitable dosage is a process of trial-and-error, including multiple drug concentration measurements and dose adjustments. A starting dose based on a patient CYP2D6 and CYP2C19 metabolizer phenotype may contribute to achieving a therapeutic concentration more quickly, possibly resulting in higher treatment efficacy and the occurrence of fewer adverse effects.ObjectivesWe aimed to study whether genotype-informed dosing in TCAs leads to faster attainment of therapeutic plasma concentrations, a higher reduction of depression severity symptoms and less adverse effects.MethodsWe conducted a double-blind randomized clinical trial, in which patients (18-65 years) diagnosed with severe MDD and eligible for treatment with a TCA were randomized in two treatment arms: The intervention arm (Pharmacogenetics Informed Treatment; PIT) and standard treatment (Treatment As Usual; TAU). Patients were treated with nortriptyline, clomipramine or imipramine for seven weeks and depressive symptom severity and adverse effects were monitored weekly. The primary outcome measure, time needed to attain a therapeutic drug concentration, was analyzed using Kaplan-Meier analyses. The secondary outcome measures, reduction in depressive symptoms and adverse effects, were analyzed with mixed model linear regression.ResultsIn total, we randomized 111 patients. The PIT group (n=56) reached a therapeutic plasma concentration significantly faster (Kaplan Meier, X2 (1) = 4.3, p=0.039) compared to TAU (n=55), especially for patients treated with nortriptyline. On average depressive symptoms decreased relatively more in PIT than in TAU, although this was not significantly different: F(6) = 0.45, p = 0.84. The severity of adverse events during the study period differed significantly between PIT and TAU (F(6)=3.10, p=0.008). PIT experienced fewer adverse effects than TAU, especially in the last two weeks of the study.ConclusionsGenotype-informed dosing leads to faster attainment of therapeutic TCA concentrations and does not lead to more adverse effects. Although we were not able to demonstrate that genotype-informed dosing leads to a significantly better response, we conclude that pharmacogenetics can contribute to the optimization of pharmacological treatment. Future research may focus on subgroups for which pharmacogenetics may be of great value, such as specific antidepressants or patients with an abnormal pharmacogenetic profile.Disclosure of InterestNone Declared

Comparative Pharmacokinetics and Injection Site Histopathology in Nude Mice Treated with Long-acting Buprenorphine Formulations.

Two long-acting formulations of buprenorphine are commercially available as analgesics for rodents. However, these drugs have not yet been studied in nude mice. We sought to investigate whether the manufacturer-recommended or labeled mouse doses of either drug would provide and sustain the purported therapeutic plasma concentration of buprenorphine (1 ng/mL) over 72 h in nude mice and to characterize the injection site histopathology. NU/NU nude and NU/+ heterozygous mice were subcutaneously injected with extended-release buprenorphine polymeric formulation (ER; 1 mg/kg), extendedrelease buprenorphine suspension (XR; 3.25 mg/kg), or saline (2.5 mL/kg). Plasma concentrations of buprenorphine were measured 6, 24, 48, and 72 h after injection. The injection site was examined histologically at 96 h after administration. XR dosing yielded significantly higher plasma buprenorphine concentrations than did ER dosing at every time point in both nude and heterozygous mice. No significant difference in plasma buprenorphine concentrations were detected between nude and heterozygous mice. Both formulations yielded plasma levels of buprenorphine of over 1 ng/mL at 6 h; XR sustained buprenorphine plasma levels above 1 ng/mL for over 48 h, whereas ER sustained this level for over 6 h. Injections sites of both formulations were characterized by a cystic lesion with a fibrous/fibroblastic capsule. ER induced more inflammatory infiltrates than did XR. This study indicates that while both XR and ER are suitable for use in nude mice, XR has a longer duration of likely therapeutic plasma levels and induces less subcutaneous inflammation at the injection site.

Virtual Clinical Trials Guided Design of an Age-Appropriate Formulation and Dosing Strategy of Nifedipine for Paediatric Use

The rapid onset of action of nifedipine causes a precipitous reduction in blood pressure leading to adverse effects associated with reflex sympathetic nervous system (SNS) activation, including tachycardia and worsening myocardial and cerebrovascular ischemia. As a result, short acting nifedipine preparations are not recommended. However, importantly, there are no modified release preparations of nifedipine authorised for paediatric use, and hence a paucity of clinical studies reporting pharmacokinetics data in paediatrics. Pharmacokinetic parameters may differ significantly between children and adults due to anatomical and physiological differences, often resulting in sub therapeutic and/or toxic plasma concentrations of medication. However, in the field of paediatric pharmacokinetics, the use of pharmacokinetic modelling, particularly physiological-based pharmacokinetics (PBPK), has revolutionised the ability to extrapolate drug pharmacokinetics across age groups, allowing for pragmatic determination of paediatric plasma concentrations to support drug licensing and clinical dosing. In order to pragmatically assess the translation of resultant dissolution profiles to the paediatric populations, virtual clinical trials simulations were conducted. In the context of formulation development, the use of PBPK modelling allowed the determination of optimised formulations that achieved plasma concentrations within the target therapeutic window throughout the dosing strategy. A 5 mg sustained release mini-tablet was successfully developed with the duration of release extending over 24 h and an informed optimised dosing strategy of 450 µg/kg twice daily. The resulting formulation provides flexible dosing opportunities, improves patient adherence by reducing frequent administration burden and enhances patient safety profiles by maintaining efficacious levels of consistent drug plasma levels over a sustained period of time.

The efficacy of the entire-vial dosing of emicizumab: Real-world evidence on plasma concentrations, bleeds, and drug waste

BackgroundProphylaxis with emicizumab provides effective bleeding protection in persons with hemophilia A (PwHA) but pressures healthcare budgets. The body weight–adjusted dosing at 7-, 14-, or 28-day intervals, according to the label, often mismatches the vial content. Entire-vial dosing resulted in therapeutic concentrations according to pharmacokinetic simulations and was introduced to avoid waste. ObjectivesThe objective of this study was to evaluate the efficacy of entire-vial dosing of emicizumab by investigating real-world evidence of plasma concentrations, bleeds, and drug waste. MethodsThis is a single-center, observational study with PwHA receiving emicizumab in mg/kg doses according to label but dosing interval extrapolated to the nearest vial size. Patient characteristics and bleeds were compared 1 year before starting emicizumab and during emicizumab until January 2022. Concentrations were assessed at weeks 4, 12, and annually. The mean (95% CI) annualized bleed rates were compared by using negative binomial regression. Drug waste between label-based dosing and entire-vial dosing was compared. ResultsA total of 112 individuals (94% severe phenotype and 9% positive FVIII inhibitors) were followed for a median of 56 weeks (interquartile range [IQR] 52-68) before and 51 weeks (IQR 29-75) after starting emicizumab. The median emicizumab dose was 5.9 (IQR 5.5-6.2) mg/kg/4 wk with median concentrations of 63 (IQR 51-80) μg/mL. The annualized bleed rate of treated bleeds before emicizumab was 3.6 (95% CI 2.9-4.4) and was 0.8 (95% CI 0.6-1.1) during emicizumab (P < .001). Drug waste was reduced by 9%. ConclusionThe entire-vial dosing of emicizumab is an attractive treatment option for PwHA leading to therapeutic plasma concentrations, good bleeding control, and drug waste avoidance.

Testing the nonclinical Comprehensive In Vitro Proarrhythmia Assay (CiPA) paradigm with an established anti-seizure medication: Levetiracetam case study.

Levetiracetam (LEV), a well-established anti-seizure medication (ASM), was launched before the original ICH S7B nonclinical guidance assessing QT prolongation potential and the introduction of the Comprehensive In Vitro Proarrhythmia Assay (CiPA) paradigm. No information was available on its effects on cardiac channels. The goal of this work was to "pressure test" the CiPA approach with LEV and check the concordance of nonclinical core and follow-up S7B assays with clinical and post-marketing data. The following experiments were conducted with LEV (0.25-7.5 mM): patch clamp assays on hERG (acute or trafficking effects), NaV 1.5, CaV 1.2, Kir 2.1, KV 7.1/mink, KV 1.5, KV 4.3, and HCN4; in silico electrophysiology modeling (Virtual Assay® software) in control, large-variability, and high-risk human ventricular cell populations; electrophysiology measurements in human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes and dog Purkinje fibers; ECG measurements in conscious telemetered dogs after single oral administration (150, 300, and 600 mg/kg). Except a slight inhibition (<10%) of hERG and KV 7.1/mink at 7.5 mM, that is, 30-fold the free therapeutic plasma concentration (FTPC) at 1500 mg, LEV did not affect any other cardiac channels or hERG trafficking. In both virtual and real human cardiomyocytes, and in dog Purkinje fibers, LEV induced no relevant changes in electrophysiological parameters or arrhythmia. No QTc prolongation was noted up to 2.7 mM unbound plasma levels in conscious dogs, corresponding to 10-fold the FTPC. Nonclinical assessment integrating CiPA assays shows the absence of QT prolongation and proarrhythmic risk of LEV up to at least 10-fold the FTPC and the good concordance with clinical and postmarketing data, although this does not exclude very rare occurrence of QT prolongation cases in patients with underlying risk factors.

ダビガトラン過量服薬に対するイダルシズマブの静脈内投与：血漿中ダビガトラン濃度と血液凝固能の関連性(Intravenous idarucizumab for dabigatran overdose: association between plasma dabigatran concentration and coagulation profile)

要旨ダビガトランは直接トロンビンを阻害することで抗凝固作用を示す経口抗凝固薬であり，近年処方機会が急増している。過量内服症例における，血漿中ダビガトラン濃度および血液凝固能の推移に関するデータは不足している。腎機能障害のない，非弁膜症性心房細動をもつ71歳邦人女性が近医より処方されていたダビガトランを合計7,480mg自殺目的に過量内服し，当院に搬送された。過量内服4時間後の血漿中ダビガトラン濃度は4,217ng/mL（治療域濃度100～400ng/mL）であり，APTTは160.3秒，PT–INRは9.46であった。イダルシズマブ5g経静脈投与後，血漿中ダビガトラン濃度は経時的に低下し，それに伴いAPTTとPT–INRも正常化した。血漿中ダビガトラン濃度とAPTT（R2=0.9898），およびPT–INR（R2=0.9998）との間には強固な関連性が認められた。本症例は第9病日に後遺症なく独歩退院した。治療域の40倍の血漿中濃度を示すダビガトラン大量内服症例において，イダルシズマブは血漿中ダビガトラン濃度を安全に，かつ効果的に低下させた。また，血液凝固能は，血漿中ダビガトラン濃度を強固に反映した。本症例により，一般的な血液凝固能検査を用いることで，ダビガトランの血中薬物動態を推定できる可能性が示された。

High-dose Meloxicam Provides Improved Analgesia in Female CD1 Mice: A Pharmacokinetic and Efficacy Study.

Meloxicam is a nonsteroidal anti-inflammatory analgesic drug that is often used in mice. However, doses of 1 to 5 mg/kg given twice daily were recently reported to provide inadequate analgesia. Some studies suggest that doses of up to 20 mg/kg may be necessary for adequate pain management. We investigated the analgesia provided by a high-dose of meloxicam in female CD1 mice. Pharmacokinetic analyses demonstrated that a subcutaneous injection of 10 mg/kg or 20 mg/kg of meloxicam produced therapeutic plasma concentrations for at least 12 h. Ovariectomies via ventral laparotomy were performed to assess analgesic efficacy. Mice were treated immediately before surgery with a high-dose of 10 mg/kg, a low-dose of 2.5 mg/kg, or saline, followed by every 12 h for 36 h. At 3, 6, 12, 24, and 48 h after surgery, mice were assessed for pain based on the following behaviors: distance traveled, time mobile, grooming, rearing, hunched posture, orbital tightening, and von Frey. Initially, some mice received a 20-mg/kg loading dose followed by 10 mg/kg every 12 h. This regimen caused severe morbidity and mortality in 2 mice. Subsequently, this regimen was abandoned, and mice assigned to the high-dose group received 10 mg/kg every 12 h. Mice that received the 10-mg/kg dose after surgery showed less orbital tightening between 3 to 6 h and reduced frequency of hunched posture for 48 h compared with mice that received either the low-dose or saline. However, mice were significantly less mobile for 6 to 12 h after surgery regardless of treatment. These data indicate that a meloxicam dose of 10 mg/kg every 12 h provides better analgesia than a 2.5-mg/kg dose but does not completely alleviate pain.

Accumulation and risk prioritization of psychoactive substances in the critically endangered Yangtze finless porpoise.

Psychoactive substances have been identified as a kind of emerging contaminants in aquatic environment and pose potential adverse effects on aquatic animals. Yangtze finless porpoise, a critically endangered species in China, is also facing the threat of psychoactive substances. In this study, the accumulation characteristics and risk prioritization of psychoactive substances were investigated in Yangtze finless porpoise collected from Poyang Lake (PYL) and Tian-E-Zhou Oxbow (TZO) in Yangtze River basin. The levels of psychoactive substances were detected in the range of below method detection limits (MDLs) to 98.4ng/mL in the serum of Yangtze finless porpoise. Codeine (COD) and methamphetamine were identified as the major substances due to the highest residual levels with a median concentration of 0.72ng/mL and 0.33ng/mL, respectively. The total concentrations of psychoactive substances in the porpoise collected from TZO was significantly higher than those from PYL. Risk analysis based on effect ratio derived from the ratio of steady-state psychoactive substance serum concentration in the porpoise and human therapeutic plasma concentration revealed that COD was the substance with the highest risk among the psychoactive substances detected, followed by lysergic acid diethylamide (LSD), morphine, alprazolam (ALPZ) and lormetazepam. Location-specific risk prioritization of psychoactive substances found that the top 3 substances are LSD, lorazepam (LORZ) and ALPZ in PYL, and COD, LSD and LORZ in TZO. The results disclose the accumulation of psychoactive substances in Yangtze finless porpoise and suggest that the potential adverse effects should be concerned.