Maximum Blood Concentration Research Articles

Bioequivalence and Pharmacokinetic Evaluation of Regorafenib Tablets in Healthy Chinese Volunteers.

This was a single-center, randomized, open-label, 2-formulation, and 2-cycle crossover trial conducted in 48 healthy Chinese volunteers, under fasting and fed conditions. The participants received oral doses of the test formulation (regorafenib) and reference formulation (40mg) during each study period. Blood samples were collected before and up to 144hours after the formulations were administered to determine changes in the pharmacokinetic parameters and adverse reactions, which were then used to evaluate bioequivalence and safety. The geometric mean ratios of maximum blood concentration, area under the plasma concentration-time curve from time 0 to the last quantifiable concentration, and area under the plasma concentration-time curve from time 0 to infinity for regorafenib were as follows: 94.7%, 91.4%, and 91.7%, respectively, under fasting conditions; and 94.6%, 97.7%, and 98.8%, respectively, under fed conditions. The 90% confidence intervals for the geometric mean ratios were within the 80%-125% equivalence interval for both the fasting and fed tests. Ingesting high-fat and high-calorie foods increases exposure to regorafenib, leading to slower rates of absorption. The safety profiles of the 2 preparations were similar.

Changes in drug crystallinity in a commercial tacrolimus amorphous formulation result in variable pharmacokinetics

Tacrolimus capsules contain the drug as the amorphous form. It is well known that drug crystallinity is a risk factor for the performance of amorphous formulations. This study investigated the impact of varying levels of crystalline drug on the pharmacokinetics of tacrolimus following oral dosing of a 5 mg capsule under fasting conditions. Two treatments with percent crystallinity of 20% and 50% were achieved by exposing a marketed generic tacrolimus product to open dish storage conditions of 35 °C and 75% relative humidity (RH) for up to 20 days. Crystallinity was monitored with X-ray powder diffraction. Prograf®, the reference listed drug (RLD), an amorphous generic drug product, and generic drug products containing 20% and 50% crystalline tacrolimus were evaluated. All four treatments were administered to healthy participants in a randomized, single-dose, four-treatment, four-period, four-way crossover study. Blood sampling occurred over 24 h. The amorphous generic tacrolimus product was determined not to be bioequivalent to the RLD. The capsules containing both 20% and 50% crystalline tacrolimus also failed the bioequivalence recommendations when compared to the amorphous generic or to the RLD. Both levels of crystalline tacrolimus resulted in BE failure for both Cmax and AUC parameters. The impact of tacrolimus crystallization was greater for maximum blood concentration (Cmax) values relative to the area-under-the-curve (AUC) values. This study demonstrates that crystalline tacrolimus formed in a marketed generic product and these changes resulted in variable pharmacokinetics which could be of significant clinical concern.

Magnetically targeted lidocaine sustained-release microspheres: optimization, pharmacokinetics, and pharmacodynamic radius of effect

ObjectiveThis study aimed to optimize the formulation of magnetically targeted lidocaine microspheres, reduce the microsphere particle size, and increase the drug loading and encapsulation rate of lidocaine. The optimized microspheres...

Solubilization of Paclitaxel with Natural Compound Rubusoside toward Improving Oral Bioavailability in a Rodent Model.

Paclitaxel, which features low water solubility and permeability, is an efflux pump substrate. The current paclitaxel drugs are given intravenously after resolving the solubility issue. Yet, oral delivery to achieve therapeutic bioavailability is not effective due to low absorption. This study evaluated a natural compound, rubusoside, to improve oral bioavailability in an animal model. Free paclitaxel molecules were processed into nano-micelles formed in water with rubusoside. The particle size of the nano-micelles in water was determined using dynamic light scattering. The oral bioavailability of paclitaxel in nano-micelles was determined against Cremophor/alcohol-solubilized Taxol after oral and intravenous administration to pre-cannulated Sprague Dawley rats. When loaded into the rubusoside-formed nano-micelles, paclitaxel reached a supersaturated concentration of 6 mg/mL, 60,000-fold over its intrinsic saturation of 0.1 µg/mL. The mean particle size was 4.7 ± 0.7 nm in diameter. Compared with Taxol®, maximum blood concentration was increased by 1.5-fold; the time to reach maximum concentration shortened to 0.8 h from 1.7 h; and, relative oral bioavailability increased by 88%. Absolute oral bioavailability was 1.7% and 1.3% for the paclitaxel nano-micelles and Taxol®, respectively. Solubilizing paclitaxel with rubusoside was successful, but oral bioavailability remained low. Further inhibition of the efflux pump and/or first metabolism may allow more oral paclitaxel to enter systemic circulation.

The Effect of Thickened Water on Ciprofloxacin Pharmacokinetics: A Comparative Study in Adult Males.

Background/Objectives: The use of food thickeners with ciprofloxacin tablets may result in a gelatinous appearance and experience delayed dissolution, which presents a challenge for the drug's efficacy, creating a healthcare economic issue. However, the pharmacokinetic impact of this compound in humans remains uncertain. Therefore, a comparative pharmacokinetic study of ciprofloxacin was conducted on healthy adult Japanese males. Methods: We compared the effects of administering tablets with water or thickened water and crushed tablets mixed with thickened water. The maximum blood concentration (Cmax) of ciprofloxacin determines the drug's efficacy. Results: There were variations in drug absorption across different administration methods. The group who took the tablets immersed in thickened water exhibited different results in the area under the blood drug concentration-time curve (AUC) and Cmax compared to the group who took the tablets in regular water. Notably, the group that consumed the crushed tablets mixed with thickened water demonstrated equivalent results for both AUC and Cmax. Conclusions: Administering crushed tablets in thickened water may yield pharmacokinetics comparable to those of tablets taken with water. However, the process of crushing tablets may result in the loss of active ingredients and compromise the formulation, necessitating a comprehensive assessment before administration.

Chitosan-modified dihydromyricetin liposomes promote the repair of liver injury in mice suffering from diabetes mellitus

Liver injury caused by type-II diabetes mellitus (DM) is a significant public-health concern worldwide. We used chitosan (CS) to modify dihydromyricetin (DHM)-loaded liposomes (DL) through charge interaction. The effect of CS-modified DL (CDL) on liver injury in mice suffering from DM was investigated in vivo and in vitro. CDL exhibited superior antioxidant capacity and stability. Pharmacokinetic analyses revealed a 3.23- and 1.92-fold increase in the drug concentration–time curve (953.60 ± 122.55 ng/mL/h) in the CDL-treated group as opposed to the DHM-treated group (295.15 ± 25.53 ng/mL/h) and DL-treated group (495.31 ± 65.21 ng/mL/h). The maximum drug concentration in blood (Tmax) of the CDL group saw a 2.26- and 1.21-fold increase compared with that in DHM and DL groups. We observed a 1.49- and 1.31-fold increase in the maximum drug concentration in blood (Cmax) in the CDL group compared with that in DHM and DL groups. Western blotting suggested that CDL could alleviate liver injury in mice suffering from DM by modulating inflammatory factors and the transforming growth factor-β1/Smad2/Smad3 signaling pathway. In conclusion, modification of liposomes using CS is a viable approach to address the limitations of conventional liposomes and insoluble drugs.

#2462 Impact of tacrolimus peak concentration on kidney graft outcomes

Abstract Background and Aims Low tacrolimus (Tac) trough concentration-to-dose ratio (C0/D ratio) identifies kidney transplant patients with high level of Tac metabolization and has been shown to be associated with lower graft function and survival. Why fast metabolizers experience poorer outcomes is however unclear. We hypothesized that fast metabolization is associated with higher maximal Tac blood concentration (Cmax) and that Tac Cmax has a detrimental effect by itself. Method We retrospectively selected consecutive kidney transplant patients who (I) were treated by Tac (irrespective of the pharmaceutical formulation), (ii) had systematic abbreviated pharmacokinetic tac evaluation at 3- and 12-months’ post-transplant, and (iii) had a minimal follow-up of 5 years. Fast metabolizers were defined by a C0/D ratio <1.05. Cmax was defined by the higher value of Tac concentration observed at 30, 90 or 180 minutes after Tac morning ingestion and was indexed to C0 in order to exclusively focus on patients with no obvious Tac overexposure. Association between Tac Cmax/C0 with traditional transplant outcomes was analysed by univariate and multivariate cox model and logrank test when appropriate. Results 436 patients transplanted from 2008 to 2016 (64% of male, mean age of 55 ± 13 y) with a median follow-up of 8 years (Q1: 6; Q3: 11) were analysed. Fast metabolizers had lower C0 while receiving higher dose of Tac and displayed significantly higher median Cmax (20 vs 17 μg/l, p < 0.001). Median Cmax/C0 was 3 and 2 in fast and non-fast metabolizers, respectively (p < 0.001). At 15 years’ post-transplant, death-censored graft survival was 13% lower for patients with the highest Cmax/C0 values (p = 0.04). In multivariate cox analysis, higher Cmax/C0 was independently associated with death-censored graft survival (HR = 1.30 (1.03;1.64), p = 0.026). Conclusion Our data support the hypotheses 1—that fast metabolizers exhibit higher Tac Cmax even in situations where Tac C0 are not elevated and 2—that exposure to high Cmax is a potential mechanism underlying their poorer outcome. Tac formulations prone to mitigate pharmacokinetic peak could thus be particularly beneficial to fast metabolizers and should be thoroughly evaluated in this indication.

Pharmacokinetic analysis of antiviral drug ritonavir across the blood–brain barrier and its interaction with Scutellaria baicalensis using multisite microdialysis in rats

Ritonavir, an excellent inhibitor of CYP3A4, has recently been combined with nirmatrelvir to form Paxlovid for the treatment of severe acute respiratory syndrome coronavirus 2 infections. The root of Scutellaria baicalensis Georgi (S. baicalensis), a traditional Chinese medicinal (TCM) herb commonly used to treat heat/inflammation in the lung and digestive tracts, which are major organs targeted by viral infections, contains flavones that can influence the CYP3A metabolism pathway. To investigate the ability of ritonavir to cross the bloodbrain barrier (BBB) and its potential herb-drug interactions with an equivalent TCM clinical dose of S. baicalensis, multisite microdialysis coupled with an LCMS/MS system was developed using rat model. Pretreatment with S. baicalensis extract for 5 days, which contains less flavones than those used in previous studies, had a significant influence on ritonavir, resulting in a 2-fold increase in the total concentration of flavones in the blood and brain. Treatment also boosted the maximum blood concentration of flavones by 1.5-fold and the maximum brain concentration of flavones by 2-fold, all the while exerting no noticeable influence on the transfer ratio across the bloodbrain barrier. These experimental results demonstrated that the use of a typical traditional Chinese medicinal dose of S. baicalensis is sufficient to influence the metabolic pathway and synergistically increase the concentration of ritonavir in rats.

In Vivo Behavior of Hydrolyzable Tannins after Oral Administration of the Trapa bispinosa Extract to Rats.

The pericarp extract of Trapa bispinosa (TBPE), which is rich in hydrolyzable tannins, has been reported to inhibit α-glucosidase and glycation reactions. We investigated the in vivo behavior of hydrolyzable tannins and related metabolites after administration of TBPE to rats. Using high pressure liquid chromatography-electrospray ionization-tandem mass spectroscopy (HPLC-ESI-MS/MS), 12 ellagitannin metabolites, such as urolithins and 6 gallotannin metabolites, produced in the collected plasma and urine were quantified. Urolithins and gallic acid metabolites reached their maximum blood concentration after 24 and 1 h of administration, respectively. Conversely, the excretion of urolithins in urine required up to 72 h and followed a sigmoidal curve, whereas gallic acid metabolites were rapidly excreted earlier after administration. The results suggest that the metabolites gallotannin and ellagitannin are responsible for the antiglycation effect of TBPE, which proceeds via different mechanisms and times. Our findings provide basic data demonstrating the functionality of hydrolyzable tannins as well as Trapa ingredients.

DAIR in treating chronic PJI after total knee arthroplasty using continuous local antibiotic perfusion therapy: a case series study

BackgroundAntimicrobial agents are administered via intramedullary antibiotic perfusion (iMAP)/intrasoft tissue antibiotic perfusion (iSAP) to infected lesions to control osteoarticular and soft tissue infections. Continuous local antibiotic perfusion (CLAP) has been reported to be useful. This study aimed to investigate the outcomes of DAIR combined with CLAP for chronic PJI after total knee arthroplasty performed at our hospital.Subjects and methodsSix patients (male; one case, female; five cases, mean age 79.5 years (70–94)) underwent CLAP for chronic PJI after TKA at our hospital between July 2020 and June 2022. They were followable for at least one year after surgery. Seven months (17–219), with a mean follow-up of 24.3 months (12–36). In addition to direct debridement and insert exchange, systemic antimicrobial treatment, and CLAP with gentamicin were performed using NPWT. We investigated the organisms causing the inflammation, the duration of iMAP/iSAP implantation, the maximum daily dose of GM, the maximum GM blood concentration, and the presence or absence of GM-induced adverse events.ResultTwo of six patients had a recurrence of infection at five weeks and five months after initial CLAP and required repeat CLAP treatment, but all patients could preserve their components. The organisms responsible for the flare-ups were MSSA in three cases: ESBL-producing E. coli, mixed MSSA and streptococcal infection, Klebsiella pneumonia in one case each, and unknown pathogens in one case. CLAP therapy for all patients was administered eight times in 6 cases: iMAP, mean: 10.0 days (5–16); iSAP, mean: 19.3 days (15–28); GM dose, mean: 162.5 mg/day (80–240); and GM blood concentration, mean: 1.4 µg/mL (0.2-5.0). Adverse events included one case of reversible acute kidney injury during CLAP in a patient with recurrent infection.SummaryDAIR with CLAP for chronic post-TKA infection can be a useful treatment option to preserve components and allow the infection to subside, provided the implant is not markedly loosened.

Novel Carbon Dots Derived from Moutan Cortex Significantly Improve the Solubility and Bioavailability of Mangiferin.

Mangiferin (MA), a bioactive C-glucosyl xanthone with a wide range of interesting therapeutic properties, has recently attracted considerable attention. However, its application in biomedicine is limited by poor solubility and bioavailability. Carbon dots (CDs), novel nanomaterials, have immense promise as carriers for improving the biopharmaceutical properties of active components because of their outstanding characteristics. In this study, a novel water-soluble carbon dot (MC-CDs) was prepared for the first time from an aqueous extract of Moutan Cortex Carbonisata, and characterized by various spectroscopies, zeta potential and high-resolution transmission electron microscopy (HRTEM). The toxicity effect was investigated using the CCK-8 assay in vitro. In addition, the potential of MC-CDs as carriers for improving the pharmacokinetic parameters was evaluated in vivo. The results indicated that MC-CDs with a uniform spherical particle size of 1-5 nm were successfully prepared, which significantly increased the solubility of MA in water. The MC-CDs exhibited low toxicity in HT-22 cells. Most importantly, the MC-CDs effectively affected the pharmacokinetic parameters of MA in normal rats. UPLC-MS analysis indicated that the area under the maximum blood concentration of MA from mangiferin-MC-CDs (MA-MC-CDs) was 1.6-fold higher than that from the MA suspension liquid (MA control) after oral administration at a dose of 20 mg/kg. Moutan Cortex-derived novel CDs exhibited superior performance in improving the solubility and bioavailability of MA. This study not only opens new possibilities for the future clinical application of MA but also provides evidence for the development of green biological carbon dots as a drug delivery system to improve the biopharmaceutical properties of insoluble drugs.

Plasma-derived C1 esterase inhibitor pharmacokinetics and safety in patients with hereditary angioedema

Over 40 years of use demonstrates that complement 1 esterase inhibitor (C1-INH) concentrate is effective and well tolerated for acute edema attacks and prophylaxis in patients with hereditary angioedema. OCTA-C1-INH is a new stable, virus-inactivated, nanofiltrated concentrate of C1-INH derived from human plasma. We investigated the pharmacokinetics and safety profile of new C1-INH in people with hereditary angioedema during an attack-free period. In this prospective, multicenter, open-label, single-arm study, adults with hereditary angioedema type I/II received a single intravenous dose of 20 IU/kg C1-INH. Blood samples were taken ≤30 minutes before infusion, and 0, 0.25, 1, 2, 6, 12, 24, 48, 72, 120, 144, and 168 hours after infusion. The primary end point was assessing the pharmacokinetic parameters of C1-INH measured by C1-INH activity. Safety end points were also examined. Twenty patients received a single dose of 20 IU/kg new C1-INH with a mean (standard deviation) total dose of 1457.3 (356.51) IU. Mean (standard deviation) area under the curve normalized by dose was 51.6 (17.9) h∙IU/mL/IU, maximum blood concentration was 1.14 (0.989) IU/mL, incremental recovery was 0.0466 (0.051) (IU∙kg)/(IU∙mL), half-life was 0.598 (0.716) hours, and time to maximum concentration was 0.598 (0.716) hours. No thromboembolic events were recorded. No treatment-emergent adverse events were rated as severe/serious. PK parameters of new C1-INH were in line with those reported for other C1-INH concentrates. New C1-INH demonstrated a favorable safety profile in patients with C1-INH deficiency. Further studies are warranted to determine the effectiveness and longer-term safety of new C1-INH.

Impact of Anticoagulant Function By the Addition of Heparinoid in Vitro in the Plasmas from Patients with Hemophilia and Von Willebrand Disease

Background: Heparinoid (Hirudoid ®) is a local anticoagulant preparation as skin application that relieves pain and inflammation with addition to promoting healing in superficial thrombophlebitis and bruising. Heparinoid is mainly composed of chondroitin sulfate and has high moisturizing ability due to the large number of hydrophilic group. Thus, it is used as topical treatments for sebum deficiency in Japan. Since heparinoid has a structure similar to heparin, the package insert states the contraindication for hemorrhagic diseases such as hemophilia and von Willebrand disease (VWD) in Japan. Hemophilia A and B (HA/HB) are inherited bleeding disorders caused by a defect in factor (F) VIII and FIX coagulant protein, respectively. Based on its activity levels, the clinical severity is classified as severe (<1 IU/dL), moderate (1-5 IU/dL), and mild (>5-40 IU/dL). VWD is the common congenital bleeding disorders and is caused by a deficiency of von Willebrand factor (VWF). VWD is classified into partial deficiency (type 1), qualitative deficiency (type 2), and complete quantitative deficiency (type 3) of VWF, based on the VWF antigen (VWF:Ag) and ristocetin cofactor activity (VWF:RCo) level. In the clinical practice, there are cases of hemorrhagic patients using heparinoid at the discretion of their families. However, the influence of heparinoid on coagulant function in human subjects remains to be investigated, and it is unclear if the patients with hemophilia and VWD can use heparinoid safely. Aim: To examine the impact of anticoagulant function of heparinoid in vitro in the plasmas from patients with hemophilia and VWD. Methods: The maximum blood concentration from absorbed heparinoid was estimated to be 2.5 µg/mL, based on the previous report, when heparinoid was applied to the skin as stated in package insert. Heparinoid (0-6.5 µg/mL) or unfractionated heparin (0-0.6 IU/mL) were added to normal plasma (NP), followed by measuring activated partial thromboplastin time (aPTT) by one-stage clotting assay. A modified clot waveform analysis (CWA) using an aPTT reagent were performed on the CS-2400™ (Sysmex), followed by measuring clotting time (CT) and adjusted maximum coagulation velocity (Ad|min1|). Heparinoid was also added to the patients' plasmas with HA, HB, or VWD, followed by CWA assessment. The CT and Ad|min1| of 20 healthy individuals were 31.1±0.1 sec and 6.90±0.05 (median±SEM). Results: aPTT and CT values in NP by the spike of heparinoid were prolonged and Ad|min1| was decreased dose-dependently. The addition of 2.5 µg/mL heparinoid showed that aPTT (34.3 sec; 1.2-fold of control (no heparinoid)), CT (36.3 sec; 1.2-fold of control), and Ad|min1| (9.5; 0.96-fold of control) were comparable to the effect of ~0.2 IU/mL heparin, suggesting that heparinoid exhibited slight anticoagulant effect for NP. To examine the effect of heparinoid on HA/HB plasmas, recombinant (r) FVIII or rFIX (0-50 IU/dL) were added to FVIII- or FIX-deficient plasmas (3 lots each) together with heparinoid (0-6.3 µg/mL), respectively. The addition of heparinoid had prolonged the CT and decreased the Ad|min1| at each concentration of FVIII and FIX dose-dependently. The addition of 2.5 µg/mL heparinoid showed modest anticoagulant effect for HA and HB at each concentration of FVIII and FIX (CT; 1.3- and 1.5-fold of control, Ad|min1|; 0.82- and 0.87-fold of control). Next, the effect of heparinoid on the plasma from one VWD patient each with type 1 (VWF:Ag/VWF:RCo 28 IU/dL/26 IU/dL), type 2 (20 IU/dL/9 IU/dL), and type 3 (<2 IU/dL/<3 IU/dL) was assessed. The addition of 2.5 µg/mL heparinoid showed slight anticoagulant effect for each type of VWD (CT; ~1.3-fold of control, Ad|min1|; ~0.91-fold of control). Conclusion: The presence of heparinoid demonstrated mild anticoagulant effect in vitro in the plasmas of patients with hemophilia and VWD. It might be possible to apply the heparinoid-contained product as skin treatment for these patients.

Cognitive outcomes at age 3 years in children with fetal exposure to antiseizure medications (MONEAD study) in the USA: a prospective, observational cohort study

The neurodevelopmental effects of fetal exposure to most antiseizure medications are unclear. We aimed to investigate the effects of fetal exposure to commonly used antiseizure medications on neuropsychological outcomes at age 3 years. The Maternal Outcomes and Neurodevelopmental Effects of Antiepileptic Drugs (MONEAD) study is a prospective, observational, multicentre cohort study at 20 specialty epilepsy centres in the USA. We have investigated pregnancy outcomes in women (aged 14-45 years) with and without epilepsy who were enrolled during pregnancy (≤20 weeks' gestational age), and their children. The primary outcome for children at age 3 years was a blindly assessed Verbal Index score, which was calculated by averaging scores on the Naming Vocabulary and Verbal Comprehension subtests of Differential Ability Scales-II, Expressive Communication and Auditory Comprehension subscales of Preschool Language Scale-5, and Peabody Picture Vocabulary Test-4. Children of women with and without epilepsy were compared, and the associations of medication exposures to outcomes in exposed children were assessed. The MONEAD study is registered with ClinicalTrials.gov, NCT0730170, and is ongoing. Between Dec 19, 2012, and Jan 13, 2016, 456 pregnant women (351 with epilepsy and 105 without epilepsy) were enrolled into the study. 345 children were born to women with epilepsy and 106 children were born to women without epilepsy. Verbal Index scores at age 3 years did not differ for children of women with epilepsy (n=284; adjusted least-square mean 102·7, 95% CI 101·4 to 103·9) versus those without epilepsy (n=87; 102·3, 99·8 to 104·7). Significant risk factors for reduced Verbal Index scores included maternal intelligence quotient, maternal education, post-birth anxiety, gestational age at enrolment, child's sex, and child's ethnicity. For Verbal Index scores, antiseizure medication exposure effects were not seen for maximum third trimester blood concentrations (n=258; adjusted parameter estimate -2·9, 95% CI -6·7 to 1·0). However, in secondary analyses, exposure-dependent effects were present on multiple cognitive measures, which varied by medication. We found no difference in neurodevelopmental outcomes between children with fetal exposure to newer antiseizure medications compared with unexposed children. However, some exposure-dependent antiseizure medication effects were seen in secondary analyses. The adverse effects of maternal post-birth anxiety emphasise the importance of screening mothers during pregnancy and postpartum and implementing interventions. Additional studies are needed to clarify the exposure-dependent effects. National Institutes of Health, National Institute of Neurological Disorders and Stroke, and National Institute of Child Health and Development.

Pharmacokinetics of ivermectin metabolites and their activity against Anopheles stephensi mosquitoes

BackgroundIvermectin (22,23-dihydroavermectin B1a: H2B1a) is an endectocide used to treat worm infections and ectoparasites including lice and scabies mites. Furthermore, survival of malaria transmitting Anopheles mosquitoes is strongly decreased after feeding on humans recently treated with ivermectin. Currently, mass drug administration of ivermectin is under investigation as a potential novel malaria vector control tool to reduce Plasmodium transmission by mosquitoes. A “post-ivermectin effect” has also been reported, in which the survival of mosquitoes remains reduced even after ivermectin is no longer detectable in blood meals. In the present study, existing material from human clinical trials was analysed to understand the pharmacokinetics of ivermectin metabolites and feeding experiments were performed in Anopheles stephensi mosquitoes to assess whether ivermectin metabolites contribute to the mosquitocidal action of ivermectin and whether they may be responsible for the post-ivermectin effect.MethodsIvermectin was incubated in the presence of recombinant human cytochrome P450 3A4/5 (CYP 3A4/5) to produce ivermectin metabolites. In total, nine metabolites were purified by semi-preparative high-pressure liquid chromatography. The pharmacokinetics of the metabolites were assessed over three days in twelve healthy volunteers who received a single oral dose of 12 mg ivermectin. Blank whole blood was spiked with the isolated metabolites at levels matching the maximal blood concentration (Cmax) observed in pharmacokinetics study samples. These samples were fed to An. stephensi mosquitoes, and their survival and vitality was recorded daily over 3 days.ResultsHuman CYP3A4 metabolised ivermectin more rapidly than CYP3A5. Ivermectin metabolites M1–M8 were predominantly formed by CYP3A4, whereas metabolite M9 (hydroxy-H2B1a) was mainly produced by CYP3A5. Both desmethyl-H2B1a (M1) and hydroxy-H2B1a (M2) killed all mosquitoes within three days post-feeding, while administration of desmethyl, hydroxy-H2B1a (M4) reduced survival to 35% over an observation period of 3 days. Ivermectin metabolites that underwent deglycosylation or hydroxylation at spiroketal moiety were not active against An. stephensi at Cmax levels. Interestingly, half-lives of M1 (54.2 ± 4.7 h) and M4 (57.5 ± 13.2 h) were considerably longer than that of the parent compound ivermectin (38.9 ± 20.8 h).ConclusionIn conclusion, the ivermectin metabolites M1 and M2 contribute to the activity of ivermectin against An. stephensi mosquitoes and could be responsible for the “post-ivermectin effect”.

Development of a pharmacological evidence-based anticholinergic burden scale for medications commonly used in older adults.

The present study aimed to develop a pharmacological evidence-based anticholinergic burden scale (ABS) through a direct assessment of muscarinic receptor-binding activities of 260 medications commonly used in older adults. The muscarinic receptor-binding activities of 260 drugs were assessed by the displacement of specific [N-methyl-3 H]scopolamine methyl chloride binding in the rat brain. The maximum blood concentrations (Cmax ) of drugs after their administration to subjects were cited from their interview forms. In total, 96 of 260 drugs displayed concentration-dependent muscarinic receptor binding in rat brain. Based on muscarinic receptor-binding activity (IC50 ) and Cmax after the administration at clinical doses in humans, we rated ABS 3 (strong) for 33 drugs and ABS 2 (moderate) for 37 drugs. There was an approximate similarity between muscarinic receptor-binding activities (IC50 ) and Cmax of 33 drugs (ABS 3) after their administration at clinical doses in humans. Furthermore, 26 drugs were defined as ABS 1 (weak) by muscarinic receptor-binding activity. The remaining 164 drugs exhibited slight or no significant muscarinic receptor-binding activities at high concentration of 100 μM, and they were defined as ABS 0. There was a marked similarity for 28 drugs (ABS 3) between the present ABS data and their previous scoring data in the literature. To our knowledge, the present study developed the first comprehensive pharmacological evidence-based ABS of drugs based on muscarinic receptor-binding activity, which provides guidance as to which drugs may be discontinued to reduce anticholinergic burden. Geriatr Gerontol Int 2023; 23: 558-564.

Development of an LC-MS/MS-based method for quantification and pharmacokinetics study on SCID mice of a dehydroabietylamine-adamantylamine conjugate, a promising inhibitor of the DNA repair enzyme

Earlier, it was found that the agent KS-389, a conjugate of dehydroabietylamine and 1-aminoadamantane, possess inhibiting activity with regard to Tdp1. It this study, LC-MS/MS-based methods of quantification of KS-389 in mice blood and several organs (brain, liver and kidney) were developed and validated. Validation of the methods was performed according to the guidelines of U.S. Food and Drug Administration and European Medicines Agency in terms of selectivity, linearity, accuracy, precision, recovery, matrix effect, stability and carry-over. Dried blood spots (DBS) method was used for blood sample preparation. HPLC separation was performed on a reversed-phase column; the total analysis time was 12 min. Mass spectral detection was performed on a 6500 QTRAP mass spectrometer in multiple reaction monitoring mode. Transitions 463.5→135.1/107.2 and 336.2→332.2/176.2 were scanned for KS-389 and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole used as the internal standard, respectively. Pharmacokinetics of the compound as well as its distribution in the organs were studied on SCID mice after intraperitoneal administration of the substance at a dose of 5 mg/kg, and it was found that its maximum concentration in blood is reached in 1–1.5 h and was 80 ng/mL. The maximum concentration in all organs is reached after the same time and is approximately 1500 ng/g and 1100 ng/g in liver and kidney, respectively. This is the first report on the pharmacokinetics of Tdp1 inhibitor based on dehydroabietylamine and 1-aminoadamantane after a single administration to mice. Also, the substance was found to be able to penetrate the blood-brain barrier which is important for, and its maximum concentration was c.a. 25–30 ng/g. These results are important for glioma treatment and make it promising for this purpose.

Toxicokinetic and mass balance of morpholine in rats

Morpholine (MOR) has a broad spectrum of use and represents high risk of human exposure. Ingested MOR can undergo endogenous N-nitrosation in the presence of nitrosating agents forming N-nitrosomorpholine (NMOR), classified as possible human carcinogen by the International Agency for Research on Cancer. In this study, we evaluated the MOR toxicokinetics in six groups of male Sprague-Dawley rats orally exposed to 14C-radiolabelled MOR and NaNO2. The major urinary metabolite of MOR, N-nitrosohydroxyethylglycine (NHEG), was measured through HPLC as an index of endogenous N-nitrosation. Mass balance and toxicokinetic profile of MOR were determined by measuring radioactivity in blood/plasma and excreta. MOR reached maximum blood concentration 30 minutes after administration. Elimination rate was rapid (70% in 8h). Most of the radioactivity was excreted in the urine (80.9 ± 0.5%) and unchanged 14C-MOR was the main compound excreted in the urine (84% of the dose recovered). 5.8% of MOR is not absorbed and/or was not recovered. Endogenous nitrosation of MOR was demonstrated by the detection of NHEG. The maximum conversion rate found was 13.3 ± 1.2% and seems to be impacted by the MOR/NaNO2 ratio. These results help refining our knowledge of the endogenous production of NMOR, a possible human carcinogen.

相対的適応で実施した血液透析で致死量摂取のアスピリン中毒を治療した1例(A case of successful treatment with hemodialysis after ingestion of a lethal dose of aspirin)

服毒自殺目的に大量摂取されたアスピリン［アセチルサリチル酸（acetylsalicylic acid: ASA）］が通常の半減期を大幅に延長していたが，血液透析により著明な症状改善を得た1例を経験したため，若干の考察とともに報告する。症例は20歳の男性，2日間にわたりASAを過量摂取（各13.2g，26.4g）し，発熱などを主訴に2回目の摂取から約8時間経過して救急外来を受診した。来院時は頻呼吸・頻脈・耳鳴症状を認め，活性炭投与，大量補液，アルカリ化利尿などの保存的治療を行ったが，症状改善に乏しく，難聴の出現，呼吸性アルカローシスと凝固機能の悪化を認めたためsalicylic acid（SA）の除去目的に血液透析を行った。初回および再検査の血中SA濃度から半減期が20.3時間と過延長していたが，2回の血液透析により，自覚症状の改善と採血結果の改善を認め，第7病日に聴力検査したところ感音難聴は改善した。中毒学的には2回目のみで考えても致死的の517mg/kgを摂取，予測最高血中濃度は1,045μg/mLと重症例であったが，血液透析により速やかな血中濃度減少を認め，有効な治療であったと考えられる。 We report a case of attempted suicide by aspirin (acetylsalicylic acid: ASA) poisoning that was markedly improved by hemodialysis. After ingesting a large dose of ASA on two days (13.2g and 26.4g, respectively), a 20–year–old man came to the emergency department on his own about 8 hours after the second intake. His chief complaint was fever, but tachypnea, tachycardia, and tinnitus were also observed at admission. Conservative treatments such as administration of activated charcoal, supplemental fluids, and alkaline diuresis were performed, but his symptoms did not improve. There was hearing loss and deteriorated coagulation function deteriorated, the patient underwent hemodialysis to remove salicylic acid (SA). The initial and subsequent blood SA concentration showed that the half–life of SA was increased to 20.3 hours; however, two hemodialysis sessions improved subjective symptoms and blood sample results, and a hearing test on the seventh day showed improvement in sensorineural hearing loss. Although the patient was severely poisoned and had a calculated maximum blood concentration of SA of 1,045μg/mL, hemodialysis effectively decreased the concentration of SA in blood. アスピリンは代表的な非ステロイド性消炎薬（NSAIDs）として処方箋なしで手に入る解熱・鎮痛剤であるとともに，抗血小板作用により虚血性心疾患や虚血性脳血管疾患の再発予防薬として有効 1であるため，広く利用されている薬剤である。その結果，自殺目的にしばしば大量服用されることがあるが，乳幼児の誤食や湿布薬と内服薬の併用などによる中毒報告もある 2, 3（Table 1）。 この論文は患者本人の同意を得て作成しており，個人情報保護法に基づいた匿名化がなされている。また，倫理委員会の承諾が必要ない発表である。 患 者：20歳の男性，体重51kg 主 訴：発熱，耳鳴，嘔気 既往・併存症・家族歴：特記事項なし 病 歴：自殺目的に2日間にわたり2回にわけてバファリンA®（ASA）を過量服薬（各40錠，80錠。330mg/錠）。2回目の内服後約8時間経過したところで発熱と嘔気，耳鳴を主訴に救急外来を独歩で受診した。 来院時の身体所見は意識清明，心拍数92bpm，血圧112/56mmHg，呼吸数28/分，SpO2 98%（室内気），体温37.0℃，発汗著明であった。呼吸音や心音に明らかな異常を認めなかった。 血液検査結果では軽度の凝固機能障害（PT–INR 1.55，APTT 32.7秒）を認めたものの，肝腎機能障害を認めず（AST 31，ALT 34，BUN 17.8，Cre 0.94)，CT検査で胃内容物を認めなかったため胃洗浄は行わなかった。通常の半減期であれば症状軽快傾向に向かうと判断し，保存的治療として大量補液，炭酸水素ナトリウム投与，経鼻胃管から活性炭，クエン酸マグネシウムを投与した。来院後6時間後の採血でPT–INR 2.88，APTT 61.7秒と凝固系の異常延長と呼吸性アルカローシスの悪化を認め（Table 2），難聴症状が明らかとなり，中毒が進行していると考え積極的な治療介入が必要と判断した。初回血液透析を施行（4時間，中空糸管であるPMMA（NF）膜2.1m2，血液流量150mL/min，抗凝固薬ナファモスタット）し，自覚症状として耳鳴は消失するも難聴症状が残存しており，聴力検査でも両側感音難聴を呈していたため翌日にも血液透析を前回と同条件で4時間施行した。第3病日の採血では凝固能を含め，明らかな異常値を呈することなく，精神状態も安定しており，希死念慮がないことを確認して退院した。第7病日に外来で聴力検査を再検査し，難聴が改善していることを確認できた（Fig. 1）。後に血中SA濃度結果が出たところで半減期が常用量では2～3時間であるのに対し，本症例では20.3時間と過延長していたことがわかった（Fig. 2, 3）。 Hearing test. 左：初回血液透析後，右：退院後（第7病日） Changes in blood SA consentration. 来院時と初回透析前の2値からFig. 3を用いて半減期を推定。その半減期を基に2回目の内服後4時間後を血中濃度のピークと仮定し，ピーク値を推定。また，初回透析後，2回目透析前からの予想半減期曲線を描いた。初回透析後にほぼ中毒レベル以下になったが半減期は初期と変わらずに延長したままである。 Half–life calculation. ASAは化学式C9H8O4，分子量180.16g/molである。主に胃・十二指腸から吸収されて肝臓でサリチル酸（salicylic acid: SA）に加水分解される 3, 4。SAは全身の組織および体液中に広く分布し，中枢神経系や母乳，胎児組織にも分布する 4, 5。タンパク結合率は血中濃度依存性を示し，低濃度域（<100μg/mL）では約90%であるのに対し，高濃度域（>400μg/mL）では約75～30%と低下する 5, 6。主に尿から排泄（80～100%）され，半減期は低用量のときは2～3時間である 3が，高容量のときは胃石を生ずることがあり持続的に吸収される 3, 4ことによったり，血中濃度の上昇に伴い代謝能が飽和し，全身クリアランスが低下したりすることで15～30時間に延長することもある 5。本症例では胃石を認めなかったが，半減期は約20時間と延長しており血中濃度上昇によりクリアランスが低下していたものと考えられる。主な中毒症状は初期症状として耳鳴，めまい，頭痛，嘔吐，難聴，軽度の頻呼吸など 3があり，血中濃度の上昇に伴い過度の過呼吸，呼吸性アルカローシス，代謝性アシドーシス，けいれん，昏睡，呼吸不全などが認められ，とくに過換気，耳鳴，嘔吐は古典的三徴とされる（Fig. 4）。処置は催吐，胃洗浄，活性炭投与，大量輸液，アシドーシス是正，重炭酸ナトリウム投与によるアルカリ化利尿，血液透析を必要に応じて行う。 Relationship between blood SA concentration and side effects/poisoning symptom. 中毒量は摂取量が150mg/kgを超えると耳鳴などの軽度の中毒症状が出現し，240mg/kgを超えると重篤となり，致死量は500mg/kgと言われている 5, 7。本症例では2日目の26.4g摂取だけで考えても517mg/kgであり致死量の摂取があったと考えられる。血中濃度の観点からみると，中毒症状はSA濃度に依存している 8とされ，200μg/mL以上で初期症状である耳鳴が出現し，270μg/mL以上で延髄の化学受容体が刺激され，悪心，嘔吐，さらに高濃度では過換気から呼吸性アルカローシスやテタニー様のけいれんを認めたりする。500～700μg/mLを超える中毒量では酸素消費と代謝速度が増すことで発熱や脱水，電解質異常などで循環不全や意識障害が出現し，最終的に腎不全に至ることもある 9。750μg/mL以上では中枢神経症状，脳浮腫，非心原生肺水腫などのリスクもある。血液透析の適応として絶対適応は900μg/mL以上 3，相対的適応は難治性アシドーシスや重篤な中枢神経症状，臨床症状の悪化などとされている 4。終了については190μg/mL以下まで継続することが望ましい 10とあり，これは蝸牛症状（難聴・耳鳴・めまい）の出現濃度にほぼ一致する。本症例では血中濃度で絶対的適応となるが，後日報告であったため来院直後の透析適応の判断はできなかったが，呼吸性アルカローシスや難聴症状，凝固機能の増悪を臨床症状の悪化と判断し，相対的適応として血液透析を施行した。 透析性については一般的に分子量が3,000以下，水との親和性が大きい，タンパク結合能が小さい，分布容積が小さいものは透析が有効とされている 11。ASA，SAについては分子量［180.16（ASA），138.12（SA）］，水溶性，分布容積が小さいため有効である。血漿タンパク結合能は治療量では80～90%と高値であるが，中毒量以上ではほとんどが遊離状態にあるため透析性は高いとされている 3。本症例では来院時852μg/mLと血液透析前606μg/mLの2値点から半減期は約20.3hrと考えられる。これを基に予測および実測血中SA濃度推移のグラフをFig. 2に示す。初回および2回目の血液透析終了時の実測値と予測血中濃度により血液透析が有効な治療法であることがわかる。また，初回血液透析後の血中濃度が211μg/mLと低値になっているにも関わらず翌日の血液透析まで半減期は変わらず約20時間で経過している。これは本症例での代謝能力が思った以上に低いことを示唆している。 SAにはビタミンK依存性凝固因子活性が抑制されることでPT時間の延長を来すこともわかっている。容量依存的にSAがビタミンKの代謝において間接的にビタミンKエポキシド還元を阻害し，還元型ビタミンKが産生できず凝固因子の合成ができないためである 12。さらに，ビタミンK依存性凝固因子は遅発性に障害される可能性がLoewらにより報告されており 13，本症例の経過にも一致する。このため，PT時間は経過観察が肝要であり，延長傾向がみられた際にはビタミンKの投与が望ましい。本症例においてはPT時間の延長理由を治療段階では判断できなかったものの，経過からSA中毒による所見と判断し，血液透析を行うことによりSA濃度を低下させることでPT時間の改善を認めた。 SAによる難聴は可逆性薬剤性難聴であり，両側に水平型の感音難聴を呈する 14。過量服薬だけでなく，各種疾患に対しての処方薬に加え湿布薬や市販の感冒薬の屯用などによる意図しない複合摂取や常用摂取だけでも難聴症状が出現することがある 3。ASAは蝸牛神経線維や有毛細胞に作用するという報告 15があり，蝸牛神経や有毛細胞の興奮性を低下させることで症状が出現しているものと考えられている 16, 17。また，難聴の程度はSA濃度に正の相関を示し 4, 18，150～200μg/mLになると難聴症状が出現し，400μg/mLまでは濃度依存的に増悪するが，それ以上になると難聴症状は進行しないとされている 19。本症例では初回血液透析後（211μg/mL）では自覚症状の改善を認めるものの症状残存，翌朝（125μg/mL）には自覚難聴症状ほぼ消失という臨床経過であった。聴力検査は血液透析後のものであるが，両側で気導・骨導とも低下しており感音難聴を呈していたが，退院後の第7病日に再検査したところ難聴所見は改善していた（Fig. 1）。 アスピリン（アセチルサリチル酸）を致死量内服し，遅発性凝固機能障害と薬剤性感音難聴を来した1例に対し血液透析を行い，救命と速やかな症状改善を認めた。本症例では摂取後から約8時間経過して来院しており，通常の半減期で考えれば血中濃度は低下し，快方に向かうと考えられたため内科的に治療を試みたが，入院後に難聴症状が明らかとなり，採血検査結果で呼吸性アルカローシスや遅発性の凝固機能異常の増悪を来したために臨床症状の悪化と判断し，相対的適応と判断して血液透析を施行するに至った。 大量摂取で摂取後数時間は徴候や症状が軽いかほとんどないこともあるが，有症状時は中毒濃度にあることから代謝が律速となり半減期は過延長している可能性が高く，代謝量＜吸収量の場合，血中濃度が上昇し，症状が悪化する。そのため，血液透析治療開始の閾値を下げて薬物を速やかに除去することにより重篤な毒性作用を回避することができるかもしれない。本症例においても脳出血などの重篤な出血合併症を来すことなく救命し得た。また，凝固機能の経過観察も必要で，増悪時にはビタミンKの投与や血液透析により速やかな改善が期待できると考える。最後に，本症例はこまめに血中濃度測定を実施することで，血液透析の実際の効果を知ることができた貴重な症例である。 本論文の投稿にあたり，開示すべきCOIはない。

Application of physiologically-based pharmacokinetic modeled toluene blood concentration in the assessment of short term exposure limits

Toluene is a volatile hydrocarbon with solvent applications in several industries. Acute neurological effects in workers exposed to toluene have been reported in various publications. To inform the basis for a toluene Short Term Exposure Limit (STEL), studies of toluene-exposed workers were modeled using customized exposure scenarios within an existing physiologically-based pharmacokinetic (PBPK) model to simulate blood concentrations during individual studies. Maximum simulated blood concentration ranged from 0.3 to 1.7 (mean = 0.74 mg/L, median = 0.73, upper 95th percentile = 1.07) at the studies identified No Observed Adverse Effect Concentration (NOAEC). Maximum simulated blood concentration ranged from 0.7 to 4.1 mg/L (mean = 1.81, median = 1.63, lower 95th percentile = 0.92) at the studies identified Lowest Observed Adverse Effect Concentration (LOAEC). The maximum blood concentration for a 100 ppm STEL-like simulation was 0.4 mg/L, at the lower end of the NOAEC range and below the 95th percentile of the LOAEC. Therefore, it appears that a STEL <100 ppm would be unnecessary to protect workers due to peak occupational exposures to toluene.