Pharmacokinetics, safety, and tolerability of the novel tetrameric gadolinium-based MRI contrast agent gadoquatrane in healthy Chinese and Japanese men: Two randomized dose-escalation studies including concentration-QTc modeling.

PURPOSE: To investigate the pharmacokinetics, safety, and tolerability of the novel tetrameric high-relaxivity gadolinium-based contrast agent gadoquatrane in Japanese (Study 1) and Chinese men (Study 2). PARTICIPANTS AND METHODS: In two similarly designed single-center, randomized, single-blind, placebo-controlled, consecutive-cohort dose-escalation studies, healthy volunteers were randomly assigned to intravenous administration of gadoquatrane (0.01-0.1 mmol gadolinium/kg body weight) or placebo. Study procedures included blood sampling and collection of urine for pharmacokinetic analyses and safety assessments. RESULTS: Twenty-five healthy Japanese men (mean age ± standard deviation: 26±5.9 years) and 23 healthy Chinese men (31±7.6 years old) were evaluated. In both studies, the pharmacokinetic profile of gadoquatrane was characterized by rapid distribution of the drug into the extracellular space and fast renal elimination. Postdose gadolinium concentrations rapidly declined with a geometric mean effective half-life of 1.3-1.4 h. The exposure increased approximately dose-proportionally with dose. The body weight-normalized volume of distribution was constant across dose levels (0.21-0.24 L/kg). Total recovery of gadolinium in urine amounted to 82-95 % (Study 1) and 96-99 % (Study 2) of the dose administered. Only a few mild, transient adverse events were reported, none of which gave rise to any safety concerns. Exploratory drug concentration-QTc modeling indicated no risk of a clinically relevant QT/QTc prolongation at the anticipated diagnostic dose. CONCLUSION: Gadoquatrane was safe and well tolerated at all doses tested. The pharmacokinetic profile was essentially the same as that of other extracellular macrocyclic gadolinium-based contrast agents and was consequentially also similar for Japanese and Chinese participants.

Effects of rifampicin on the pharmacokinetics and safety of carotegrast methyl in healthy subjects: A randomized 2 × 2 crossover study.

AIMS: To evaluate the effect of the combination of carotegrast methyl with rifampicin, a potent inhibitor of organic anion transporter polypeptide, on the pharmacokinetics (PKs), safety and tolerability of carotegrast methyl. METHODS: In this 2 × 2 crossover study in 20 healthy Japanese adults, 10 subjects received carotegrast methyl 960 mg and rifampicin 600 mg on day 1 and received carotegrast methyl 960 mg on day 8. The subjects in the other sequence received the same treatments but in the opposite order. The 90% confidence interval (CI) of the geometric mean ratio of the Cmax and AUC0-t for carotegrast, the main active metabolite of carotegrast methyl, with/without rifampicin was calculated. If the 90% CI fell within the range of 0.80-1.25, this indicated the absence of any drug-drug interaction. Adverse events (AEs) were monitored. RESULTS: The geometric mean ratios (90% CI) of the Cmax and AUC0-t for carotegrast with/without rifampicin were 4.78 (3.64-6.29) and 5.59 (4.60-6.79), respectively, indicating that carotegrast has a PK interaction with rifampicin. The combination with rifampicin increased the exposure of carotegrast and also that of its metabolites. The incidence of any AEs with/without rifampicin was five (25.0%) and one (5.0%), respectively. CONCLUSIONS: Coadministration of carotegrast methyl with rifampicin significantly increased the exposure of carotegrast compared with carotegrast methyl administration alone. In this single dose study, the incidence of AEs of carotegrast methyl with rifampicin increased compared with carotegrast methyl alone, but the incidence of adverse drug reactions did not increase with combination administration.

Safety, Tolerability, and Pharmacokinetics of Valemetostat Tablets and the Effect of Food on Valemetostat Pharmacokinetics in Healthy Subjects: Two Phase 1 Studies.

Valemetostat is an oral, selective inhibitor of enhancer of zeste homolog-2 (EZH2) and EZH1. In a first-in-human phase-1 trial, valemetostat capsules were well tolerated and clinically active in patients with relapsed/refractory non-Hodgkin lymphoma. Subsequently, a film-coated tablet formulation was developed for future clinical trials and commercialization. We report outcomes from 2 phase 1 trials in healthy Japanese participants, assessing the safety, tolerability, and pharmacokinetics (PK) of valemetostat tablets at single ascending doses (50, 100, and 200-mg), the relative bioavailability between capsules and tablets, and the effect of food (high-fat or low-fat meals) on the PK of valemetostat tablets. In the ascending-dose study, valemetostat maximum plasma concentration (Cmax ) and area under the concentration-time curve (AUC) increased dose-proportionally. Valemetostat plasma PK parameters were similar between the capsule and tablet formulations following a single 200-mg dose. Administration of valemetostat, 200 mg after a meal, was associated with 50%-60% lower Cmax , 30%-50% lower AUC, and a median Tmax delay of 2.5-3 hours relative to fasted administration. Valemetostat was well tolerated in healthy subjects; treatment-emergent adverse events were mild (grade 1) in severity. Based on these trials, the tablet formulation of valemetostat is suitable for use in subsequent clinical trials and should be administered under fasted conditions to avoid a negative food effect.

Evaluation of the potential drug-drug interactions of carotegrast methyl with midazolam, prednisolone or atorvastatin in healthy adults.

AIMS: This study evaluated drug-drug interactions between the CYP3A4 inhibitor carotegrast methyl and the other CYP3A4 substrates, midazolam, atorvastatin and prednisolone. METHODS: A total of 88 healthy volunteers orally received carotegrast methyl 960 mg 3 times daily for 14 days. A single oral (5 mg) or intravenous (0.017 mg kg-1 ) midazolam, oral (5 mg) prednisolone or oral (10 mg) atorvastatin was administered before, with and after carotegrast methyl treatment. When the 90% confidence interval (CI) for the geometric mean ratios of the pharmacokinetic (PK) parameters with coadministration with carotegrast methyl (Day 14) to those before carotegrast methyl administration was between 0.80 and 1.25, no PK interaction were deemed. RESULTS: The Cmax and AUC0-t of oral midazolam before administration of carotegrast methyl were 30.9 ± 9.8 ng mL-1 and 74.5 ± 21.9 ng h mL-1 , respectively. The geometric mean ratio of the Cmax and AUC0-t of midazolam on Day 14 to those on Day -1 was 1.86 (90% CI, 1.64-2.11) and 3.07 (90% CI, 2.81-3.35), which did not fall within the range of 0.80-1.25, suggesting that carotegrast methyl had a PK interaction with midazolam. Similar PK interactions were found for intravenous midazolam and atorvastatin, but not for prednisolone. The inhibitory effect of carotegrast methyl on CYP3A4-mediated metabolism of midazolam and atorvastatin had almost disappeared by 14 days after the end of administration. CONCLUSION: Carotegrast methyl was classified as a moderate CYP3A4 inhibitor in humans. Carotegrast methyl might enhance the action of drugs that are metabolized by CYP3A4.

Effect of itraconazole and fluconazole on the pharmacokinetics of valemetostat: An open-label, phase I study in healthy subjects.

Valemetostat tosylate (valemetostat) is an oral, potent, dual inhibitor of enhancer of zeste homolog (EZH) 2 and EZH1 under investigation for the treatment of cancer, including non-Hodgkin's lymphomas and solid tumors. Itraconazole and fluconazole are antifungal medications often used as typical inhibitors of cytochrome P450 3A (CYP3A [itraconazole and fluconazole]) and P-glycoprotein (P-gp [itraconazole]) in drug-drug interaction studies. Valemetostat is a substrate of CYP3A and P-gp in vitro. This phase I, open-label, single-sequence crossover study (JapicCTI-183902) assessed the pharmacokinetics (PK) of valemetostat when co-administered with itraconazole (a strong CYP3A inhibitor and P-gp inhibitor) or fluconazole (a moderate CYP3A inhibitor) in healthy Japanese male participants 20-45 years of age. Participants were equally allocated to receive two doses of valemetostat 25 mg, once alone and once with either itraconazole or fluconazole (400-mg induction and 200-mg once daily maintenance). Valemetostat PK parameters with versus without itraconazole or fluconazole were compared using analysis of variance models. Overall, 32 participants were enrolled. Co-administration with itraconazole increased valemetostat peak concentration (Cmax ) by 2.9-fold and area under the plasma concentration-time curve extrapolated to infinity (AUCinf ) by 4.2-fold compared with valemetostat alone. When co-administered with fluconazole, the Cmax and AUCinf of valemetostat were each increased by 1.6-fold. No treatment-related or grade ≥3 adverse events were reported. Appropriate valemetostat dose reductions are warranted when used concomitantly with strong CYP3A and P-gp dual inhibitors.

Effect of γ-tocopherol supplementation on premenstrual symptoms and natriuresis: a randomized, double-blind, placebo-controlled study.

BACKGROUND: This randomized, double-blind, placebo-controlled study aimed to investigate the effects of γ-tocopherol (Toc) supplementation on premenstrual symptoms and natriuresis. METHODS: We enrolled 51 Japanese women with premenstrual symptoms, particularly those who showed increased symptoms induced by water retention during the luteal phase compared with the follicular phase. Premenstrual symptoms were recorded in the first cycle's postmenstrual follicular phase; physical measurements and urine collection were conducted during the 48-h run-in period. The test supplement, which contained 180 mg of γ-Toc or placebo, was orally administered twice a day for 7 days during the luteal phase of the first and second cycles in a crossover manner. The same evaluation was conducted during the luteal phase, beginning in the morning of the sixth day of supplement administration. RESULTS: Compared with placebo intake, γ-Toc intake significantly reduced "fatigue" and "irritability/anger" symptoms. Furthermore, compared with placebo intake, γ-Toc intake significantly reduced the thigh circumference. Regarding the "swelling of the legs" and "heavy legs" symptoms and the thigh circumference, the biphasic trend of increasing and decreasing values in the daytime and morning, respectively, during the follicular phase was not observed at the luteal phase with placebo intake. Contrastingly, γ-Toc intake resulted in significantly lower values in the morning than placebo intake. The mean difference in 24-h urinary sodium excretion between γ-Toc and placebo intake was 10.6 mEq (95% confidence interval (CI): -0.1, 21.4, p = 0.05, power 55%). Plasma γ-Toc and its metabolite γ-carboxyethyl hydroxychroman (CEHC) levels were significantly higher with γ-Toc intake than with placebo intake. There were no significant between-supplement differences in serum electrolyte levels or cumulative urinary potassium excretion. CONCLUSION: γ-Toc intake could effectively alleviate certain premenstrual syndrome symptoms, particularly those related to water retention during the luteal phase. Furthermore, the underlying mechanism may involve the diuretic effect of γ-CEHC, which is a γ-Toc metabolite. TRIAL REGISTRATION: UMIN000047989; registration date: 10/06/2022, retrospectively registered.

Single- and Multiple-Dose Pharmacokinetics and Safety of Vilaprisan in Healthy Postmenopausal Japanese Women: A Randomized Clinical Trial.

BACKGROUND AND OBJECTIVES: As the prevalence of some gynecological conditions depends on patient characteristics such as race/ethnicity, it is important to study therapies for these conditions in diverse populations. The study described in this article was conducted to investigate the safety, tolerability, and pharmacokinetics of vilaprisan, a selective progesterone receptor modulator, in Japanese women in Japan. It supplements two comparable studies that were conducted in healthy postmenopausal European and Chinese women, respectively. METHODS: In this exploratory randomized, placebo-controlled, double-blind, ascending-dose study, five groups of healthy postmenopausal Japanese women received vilaprisan as immediate-release tablets (1, 5, or 15 mg as a single dose or 1 or 5 mg/day for 28 days) or placebo tablets (single dosing: 8 subjects/dose step, thereof 2 subjects randomized to placebo; multiple dosing: 12 subjects/dose step, thereof 4 subjects randomized to placebo). Blood samples for pharmacokinetic profiles were collected over 14-19 days. Safety assessments were based on adverse event data, vital signs, electrocardiograms, clinical laboratory tests, and transvaginal ultrasound examinations. RESULTS: 48 participants were randomized, treated, and analyzed. Vilaprisan was rapidly absorbed, reaching maximum plasma concentrations (Cmax) between 1 and 3 h post dose. Post maximum, plasma concentrations rapidly declined, indicating pronounced distribution into tissues. The exposure of vilaprisan increased roughly dose-proportionally: The geometric mean (geometric coefficients of variation) areas under the concentration time curves from time zero to infinity (AUC∞) after single administration of 1, 5, or 15 mg vilaprisan were 67 µg·h/l (34%), 249 µg·h/l (15%), and 788 µg·h/l (37%), respectively. The AUC in the dosing interval after multiple administrations (AUC24,md) of 1 mg/day was 76 µg·h/l (59%), and the AUC24,md after 5 mg/day was 311 µg·h/l (20%). Geometric mean Cmax values also increased roughly dose-proportionally: They amounted to 6 µg/l (22%), 16 µg/l (33%), and 52 µg/l (27%) after single administration and to 8 µg/l (28%) and 31 µg/l (22%) after multiple administrations of the above doses. Mild adverse events were observed, similar to those observed in other clinical studies of vilaprisan. CONCLUSIONS: Overall, vilaprisan was safe and well tolerated. The exposure in Japanese women was similar to that observed in European and Chinese women in separate studies. TRIAL REGISTRATION: 15 Nov 2011 (no registration number assigned).

Effects of a reactive oxygen species generator, napabucasin (BBI608), on tolerability, safety, pharmacokinetics, and QT/QTc interval in healthy volunteers.

This study examined the safety, tolerability, and pharmacokinetics (PK) of napabucasin in healthy Asian and non-Asian participants and investigated the potential for QT/QTc interval prolongation. This five-part (A-E) study proceeded in a stepwise manner, unless stopping criteria were met. Parts A-D were randomized, double-blind, placebo-controlled, and included healthy Asian male and female and non-Asian male participants. PK parameters were measured following single-dose napabucasin (80-1200 mg) in the fasted or fed state (Part D). Potential QT/QTc interval prolongation was assessed using digital 12-lead electrocardiogram (Parts B and C). Part E was open-label, and examined the PK of single-dose napabucasin (240-720 mg) in healthy non-Asian males. Safety and tolerability were measured in Parts A-E. Changes from baseline in the Fridericia-corrected QT interval (ΔQTcF) and other electrocardiogram parameters were analyzed using a linear mixed-effects model. Napabucasin was well-tolerated across the study (n = 70), and no serious adverse events or significant safety issues were reported when administered with or without food. The most frequent treatment-emergent adverse events were diarrhea and abdominal pain, and these were mild in severity. No prolongation of the QTcF interval was reported following single-dose napabucasin (240-1200 mg) and changes in other cardiac parameters were negligible. The PK profile of napabucasin was consistent with earlier studies. Single-dose napabucasin was tolerated in healthy male and female participants, and no significant safety (including no QTcF prolongation) or tolerability issues were identified, irrespective of food intake. Clinical studies of napabucasin in advanced cancers are ongoing.

Cerebrospinal Fluid Protein Concentration in Healthy Older Japanese Volunteers.

The concentration of cerebrospinal fluid total protein (CSF-TP) is important for the diagnosis of neurological emergencies. Recently, some Western studies have shown that the current upper reference limit of CSF-TP is quite low for older patients. However, little is reported about the concentration of CSF-TP in the older Asian population. In this study, we retrospectively analyzed the CSF-TP concentrations in healthy older Japanese volunteers. CSF samples in 69 healthy Japanese volunteers (age range: 55-73 years) were collected by lumbar puncture, and the data of CSF were retrospectively analyzed. The mean (standard deviation) CSF-TP was 41.7 (12.3) mg/dL. The older group (≥65 years old) had higher CSF-TP concentration than the younger group (55-64 years old). The 2.5th percentile and 97.5th percentile of CSF-TP were estimated as 22.5 and 73.2 mg/dL, respectively, which were higher than the current reference range in Japan (10-40 mg/dL). Conclusions: The reference interval of CSF-TP in the older population should be reconsidered for the precise diagnosis of neurological emergencies.

Statistical Analysis of the Axillary Temperatures Measured by a Predictive Electronic Thermometer in Healthy Japanese Adults.

Body temperature is important for diagnosing illnesses. However, its assessment is often a difficult task, considering the large individual differences. Although 37 °C has been the gold standard of body temperature for over a century, the temperature of modern people is reportedly decreasing year by year. However, a mean axillary temperature of 36.89 ± 0.34 °C reported in 1957 is still cited in Japan. To assess the measured axillary temperature appropriately, understanding its distribution in modern people is important. This study retrospectively analyzed 2454 axillary temperature measurement data of healthy Japanese adults in 2019 (age range, 20-79 years; 2258 males). Their mean temperature was 36.47 ± 0.28 °C (36.48 ± 0.27 °C in males and 36.35 ± 0.31 °C in females). Approximately 5% of the 20-39-year-old males had body temperature ≥37 °C, whereas 8% had a temperature ≥ 37 °C in the afternoon. However, none of the subjects aged ≥50 years reported body temperature ≥37 °C. In multivariable regression analysis, age, blood pressure, pulse rate, and measurement time of the day were associated with axillary temperature. Our data showed that the body temperature of modern Japanese adults was lower than that reported previously. When assessing body temperature, the age, blood pressure, pulse rate, and measurement time of the day should be considered.

SARS-CoV-2 Seroprevalence among Healthcare Workers in General Hospitals and Clinics in Japan.

Coronavirus disease 2019 (COVID-19) has become a serious public health problem worldwide. In general, healthcare workers are considered to be at higher risk of COVID-19 infection. However, the prevalence of COVID-19 among healthcare workers in Japan is not well characterized. In this study, we aimed to examine the seroprevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antibodies among 2160 healthcare workers in hospitals and clinics that are not designated to treat COVID-19 patients in Japan. The prevalence of SARS-CoV-2 immunoglobulin G was 1.2% in August and October 2020 (during and after the second wave of the pandemic in Japan), which is relatively higher than that in the general population in Japan (0.03-0.91%). Because of the higher risk of COVID-19 infection, healthcare workers should be the top priority for further social support and vaccination against SARS-CoV-2.

Comparative pharmacokinetics of maxacalcitol in healthy Taiwanese and Japanese subjects.

Pharmacokinetic studies of maxacalcitol in healthy Taiwanese subjects have been conducted. This study to compare the pharmacokinetic properties of maxacalcitol in healthy Taiwanese and Japanese subjects. Healthy male Taiwanese subjects (n = 24) and healthy male Japanese subjects (n = 24) were enrolled in separate single-center and received a single intravenous dose of 1.25, 2.5 and 5 µg maxacalcitol. Male subjects were exclusively employed in the study due to the first administration of maxacalcitol to Taiwanese. Serum samples were collected for up to 72 h for pharmacokinetic analysis, and safety was assessed. Exposures to maxacalcitol as mean C5 and AUCinf appeared to increase with increase of doses in Taiwanese subjects (C5: 74.0, 159, and 321 pg/mL; AUCinf: 473, 763, and 1460 hï½¥pg/mL) and Japanese subjects (C5: 92.9, 174, and 346 pg/mL; AUCinf: 312, 588, and 1040 hï½¥pg/mL). After single bolus IV administration, linearity in maxacalcitol exposure was shown over the dose range of 1.25-5 µg in both Taiwanese and Japanese male healthy subjects. C5 of maxacalcitol was slightly lower (85%) in Taiwanese compared with that in Japanese and AUCinf of maxacalcitol in Taiwanese subjects was contrarily 15.0 (41.6%) higher than that in Japanese subjects, resulted in not much difference in pharmacokinetics of maxacalcitol between Taiwanese and Japanese. Moreover, maxacalcitol was well tolerated in both healthy Taiwanese and Japanese subjects.

A Phase 1, Randomized, Placebo-Controlled Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Immunogenicity of Subcutaneous Tezepelumab in Healthy Japanese Men.

Tezepelumab, a human immunoglobulin G2 monoclonal antibody against thymic stromal lymphopoietin, is currently under clinical development for the treatment of severe, uncontrolled asthma. This phase 1, randomized, placebo-controlled, single-ascending-dose study assessed the safety, tolerability, pharmacokinetics, and immunogenicity of subcutaneous tezepelumab in healthy Japanese men. Participants were assigned to 1 of 3 tezepelumab dose cohorts (35, 105, or 280 mg; n = 8 per cohort) and randomized (6:2) to receive a single subcutaneous dose of tezepelumab or placebo, with a follow-up period of 84 to 112 days. The overall incidences and severities of treatment-emergent adverse events were similar across tezepelumab doses and between the tezepelumab and placebo groups. Tezepelumab was absorbed slowly, reaching a maximum serum concentration (mean, 5.2-39.7 µg/mL) after 7 to 10 days. Area under the concentration-time curve (mean, 207.2-1612.0 µg · day /mL) increased in an approximate dose-proportional manner. Tezepelumab had a long terminal serum half-life (mean, 23.9-26.3 days) and a small apparent distribution volume, suggesting limited distribution into peripheral tissues. No participants developed anti-tezepelumab antibodies. Single-dose, subcutaneous administration of tezepelumab 35 to 280 mg resulted in an acceptable safety profile with linear pharmacokinetics in healthy Japanese men. No clear differences in tezepelumab safety and pharmacokinetics between Japanese and non-Japanese populations were identified.

Elucidation of N 1-methyladenosine as a Potential Surrogate Biomarker for Drug Interaction Studies Involving Renal Organic Cation Transporters.

Endogenous substrates are emerging biomarkers for drug transporters, which serve as surrogate probes in drug-drug interaction (DDI) studies. In this study, the results of metabolome analysis using wild-type and Oct1/2 double knockout mice suggested that N 1-methyladenosine (m1A) was a novel organic cation transporter (OCT) 2 substrate. An in vitro transport study revealed that m1A is a substrate of mouse Oct1, Oct2, Mate1, human OCT1, OCT2, and multidrug and toxin exclusion protein (MATE) 2-K, but not human MATE1. Urinary excretion accounted for 77% of the systemic elimination of m1A in mice. The renal clearance (46.9 ± 4.9 ml/min per kilogram) of exogenously given m1A was decreased to near the glomerular filtration rates by Oct1/2 double knockout or Mate1 inhibition by pyrimethamine (16.6 ± 2.6 and 24.3 ± 0.6 ml/min per kilogram, respectively), accompanied by significantly higher plasma concentrations. In vivo inhibition of OCT2/MATE2-K by a single dose of 7-[(3R)-3-(1-aminocyclopropyl)pyrrolidin-1-yl]-1-[(1R,2S)-2-fluorocyclopropyl]-8-methoxy-4-oxoquinoline-3-carboxylic acid in cynomolgus monkeys resulted in the elevation of the area under the curve of m1A (1.72-fold) as well as metformin (2.18-fold). The plasma m1A concentration profile showed low diurnal and interindividual variation in healthy volunteers. The renal clearance of m1A in younger (21-45 year old) and older (65-79 year old) volunteers (244 ± 58 and 169 ± 22 ml/min per kilogram, respectively) was about 2-fold higher than the creatinine clearance. The renal clearances of m1A and creatinine were 31% and 17% smaller in older than in younger volunteers. Thus, m1A could be a surrogate probe for the evaluation of DDIs involving OCT2/MATE2-K. SIGNIFICANCE STATEMENT: Endogenous substrates can serve as surrogate probes for clinical drug-drug interaction studies involving drug transporters or enzymes. In this study, m1A was found to be a novel substrate of renal cationic drug transporters OCT2 and MATE2-K. N 1-methyladenosine was revealed to have some advantages compared to other OCT2/MATE substrates (creatinine and N 1-methylnicotinamide). The genetic or chemical impairment of OCT2 or MATE2-K caused a significant increase in the plasma m1A concentration in mice and cynomolgus monkeys due to the high contribution of tubular secretion to the net elimination of m1A. The plasma m1A concentration profile showed low diurnal and interindividual variation in healthy volunteers. Thus, m1A could be a better biomarker of variations in OCT2/MATE2-K activity caused by inhibitory drugs.

Effects of magnesium oxide on pharmacokinetics of L-dopa/carbidopa and assessment of pharmacodynamic changes by a model-based simulation.

BACKGROUND: Magnesium oxide (MgO) is often co-prescribed with L-dopa/carbidopa (LDCD) to improve constipation in Parkinson's disease patients. The mixing of L-dopa and MgO has been shown to degrade L-dopa; however, there is no interaction study on humans. We proposed mechanisms for the interaction between LDCD and MgO and conducted pharmacokinetic studies on rats and humans. To assess pharmacodynamic changes with the MgO treatment, we applied a model-based meta-analysis (MBMA). METHODS: The effects of MgO on the stabilities of L-dopa and carbidopa were evaluated in in vitro studies. We conducted pharmacokinetic interaction studies of MgO and LDCD on rats and healthy volunteers. A clinical study was conducted with an open-label, non-randomized, single-arm, and two-phase study. In MBMA, we constructed a population pharmacokinetic/pharmacodynamic model of L-dopa and predicted the effects of the MgO treatment on the pharmacodynamics of L-dopa. RESULTS: In vitro results suggested that carbidopa was unstable under alkaline pH conditions. Reductions in plasma LDCD concentrations were observed after oral-MgO/oral-LDCD, but not in oral-MgO/i.v.-LDCD treatments in rats, suggesting that the gastrointestinal tract is an interaction site. A healthy volunteer study showed that MgO was also associated with significant decreases of 35.3 and 80.9% in the AUC0-12 of L-dopa and carbidopa, respectively. A model-based simulation suggested that the MgO treatment was undesirable for the effectiveness of L-dopa. CONCLUSIONS: This is the first study to show a clear pharmacokinetic interaction between LDCD and MgO in humans. Further investigations to confirm the effects of MgO on the pharmacodynamics of L-dopa are required.

Effect of OATP1B1 genotypes on plasma concentrations of endogenous OATP1B1 substrates and drugs, and their association in healthy volunteers.

This study aimed to elucidate the impact of OATP1B1 genotype (*1b/*1b, *1b/*15, and *15/*15) on plasma concentrations of endogenous OATP1B1 substrates. Healthy volunteers with OATP1B1 *1b/*1b (n = 10), *1b/*15 (n = 7), or *15/*15 (n = 2) received oral administration of a cocktail of statins (atorvastatin, pitavastatin, rosuvastatin, and fluvastatin). Mean area under the plasma concentration of atorvastatin, pitavastatin, and rosuvastatin in OATP1B1 *15/*15 were 2.2, 1.7 and 1.58-times greater than the corresponding values in OATP1B1 *1b/*1b, respectively, whereas that of fluvastatin was identical to those in other OATP1B1 genotypes. OATP1B1 *15/*15 also showed higher mean plasma concentrations of OATP1B1 endogenous substrates compared with the other OATP1B1 genotypes, such as coproporphyrin I, glycochenodeoxycholate sulfate (GCDCA-S), lithocholate sulfate (LCA-S), glycolithocholate sulfate (GLCA-S) and taurolithocholate sulfate (TLCA-S), but not total or direct bilirubin, chenodeoxycholate-24-glucuronide, or ω-dicarboxylic long-chain fatty acids. Area under the plasma concentration-time curves of plasma coproporphyrin I and GLCA-S discriminated OATP1B1 genotype *15/*15 from the other genotypes. In combination with previously published clinical studies, these results support the notion that coproporphyrin I, and GLCA-S and GCDCA-S could be a surrogate probe for assessing human in vivo OATP1B1 activities.

Clinical Drug-Drug Interaction Potential of BFE1224, Prodrug of Antifungal Ravuconazole, Using Two Types of Cocktails in Healthy Subjects.

BFE1224, prodrug of ravuconazole, is a novel, once-daily, oral, triazole antifungal drug, and currently in development for the treatment of onychomycosis. The clinical drug-drug interaction (DDI) potential of BFE1224 with cytochrome P450 (CYP) and transporter was assessed by using two types of cocktails in healthy subjects in separate clinical studies. The CYP and transporter cocktails consisted of caffeine/tolbutamide/omeprazole/dextromethorphan/midazolam used in study 1 and digoxin/rosuvastatin used in study 2. In addition, repaglinide was separately administered to the same subjects in study 2. There were no major effects on the pharmacokinetics of CYP and transporter substrates, except for an approximate threefold increase in midazolam exposure after oral administration of BFE1224. The clinical DDIs of BFE1224 were mild for CYP3A and minor for other major CYPs (CYP1A2/2C8/2C9/2C19/2D6) as well as those of P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), organic anion transporting polypeptide (OATP) 1B1, and OATP1B3.

The Effect of Drug Content Reduction on the In Vitro and In Vivo Properties of Levonorgestrel-Releasing Intravaginal Rings.

Intravaginal rings (IVRs) are an option for continuous administration of drugs in women. However, a considerable amount of excess drug often remains in the ring upon removal. The current study focuses on comparing 2 IVRs releasing levonorgestrel (LNG). Both formulations were designed to release 40 µg of LNG daily, however, with a significant difference in the total amount of drug (10.6 vs. 176.9 mg). Numerical simulations and in vitro release rate testing were utilized in designing the IVRs and confirming the similarity of drug release. Moreover, a pharmacokinetic (PK) study was performed in 13 healthy Japanese women to investigate both formulations during the intended wearing period of 28 days. The primary PK metrics was the average concentration of LNG in plasma at defined time points under stable conditions. Statistical evaluation of the ratio of the main PK metrics indicated values almost in the bioequivalence range. Furthermore, drug content determinations for used and unused IVRs were analyzed for confirming the expected drug delivery in vivo. In summary, it was shown that with proper design, even major differences in the total drug content of IVR formulations might not result in significant effects in the in vitro and in vivo release properties.

BACE1 Inhibitor Lanabecestat (AZD3293) in a Phase 1 Study of Healthy Japanese Subjects: Pharmacokinetics and Effects on Plasma and Cerebrospinal Fluid Aß Peptides.

Lanabecestat (AZD3293; LY3314814) is an orally active potent inhibitor of human ß-secretase 1 in clinical development for the treatment of Alzheimer disease. In this first Japanese clinical study for an Alzheimer disease intervention to include cerebrospinal fluid (CSF) sampling in Japanese elderly healthy subjects, we report the pharmacokinetics and effects on plasma and CSF amyloid-ß (Aß) peptides of lanabecestat in a phase 1 study involving 40 healthy Japanese subjects (NCT02005211). No safety and tolerability concerns were identified in healthy Japanese subjects exposed to lanabecestat up to the highest doses given, which is consistent with observations in a US phase 1 study of lanabecestat. Exposure to lanabecestat was similar for young and elderly subjects and increased in a dose-dependent manner. For elderly subjects, plasma lanabecestat half-life after multiple dosing was 12 to 17 hours (on days 10 and 14). Robust plasma and CSF Aß peptide reductions were also seen at all doses, with CSF Aß42 concentrations reduced by 63% and 79% in the 15- and 50-mg lanabecestat groups, respectively. CSF soluble amyloid-ß precursor protein ß also decreased following lanabecestat treatment. Suppression of CSF Aß peptides was similar in elderly healthy Japanese subjects and US patients with mild to moderate Alzheimer disease. Lanabecestat is a promising potentially disease-modifying treatment in phase 3 development for patients with early Alzheimer disease.

Involvement of Organic Cation Transporters in the Kinetics of Trimethylamine N-oxide.

Recent studies suggest that trimethylamine N-oxide (TMAO) is associated with the development of chronic kidney disease and heart failure. In this study, we investigated the importance of organic cation transporters (OCTs) in the clearance and tissue distribution of TMAO. The low-affinity and high-capacity transport of TMAO by mouse and human OCT1 and OCT2 was observed. Uptake and efflux of TMAO by the mouse hepatocytes as well as TMAO uptake into mouse kidney slices were significantly decreased by the addition of tetraethylammonium or Oct1/2 double knockout (dKO). Plasma concentrations of endogenous TMAO and TMAO-d9 given by intravenous infusion was 2-fold higher in Oct1/2 dKO than in wild-type mice due to significant decrease in its renal clearance. These results indicate that OCTs have a crucial role in the kinetics of TMAO in mice. In human, however, the OCT2-mediated tubular secretion in the urinary excretion of TMAO was insignificant because the renal clearance of TMAO was similar to that of creatinine in both young and elderly subjects, suggesting the species difference in the urinary excretion mechanisms of TMAO between mouse and human.