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To evaluate the pharmacokinetic (PK) and tolerability profiles of a new tablet formulation of tacrolimus and its interindividual variability (IIV) in the systemic exposure, and to compare them with those of the conventional capsule formulation, a randomized, open-label, two-treatment, two-period, two-sequence, crossover study was performed in 47 healthy males. The capsule or tablet formulation of tacrolimus was orally administered, and serial blood samples were collected up to 96 hours after dosing. Whole-blood tacrolimus concentration was determined using liquid chromatography-tandem mass spectrometry. The maximum whole-blood tacrolimus concentration (C ) and the area under the whole-blood tacrolimus concentration-time curve from 0 hour to the last quantifiable concentration (AUC ) were compared between the two formulations. The similarity factor (f ) of the in vitro dissolution profiles was calculated. The geometric mean ratio (90% confidence interval) of tablet to capsule was 0.9680 (0.8873-1.0560) and 1.0322 (0.9359-1.1385) for C and AUC , respectively. The IIV of C and AUC of the tablet was smaller than the capsule. The f values were >50 in all media. Both formulations were well tolerated. Thus, the tablet formulation of tacrolimus has smaller IIV in the systemic exposure than capsule, while having comparable PK and tolerability profiles, which may render it as a better treatment option for organ transplant patients.

•Newly developed esomeprazole/magnesium hydroxide fixed-dose combination (FDC) exhibits faster time to reach maximum concentration compared to enteric-coated esomeprazole.•The FDC demonstrates a shorter time to achieve gastric pH ≥ 4, indicating more rapid and effective acid suppression compared to enteric-coated esomeprazole.•Comparable systemic exposure and decrease in integrated gastric acidity over 24 hours highlight equivalent inhibition of gastric acid secretion between the FDC and enteric-coated esomeprazole.•The esomeprazole/magnesium hydroxide FDC presents as a promising option with faster absorption and effective gastric acid suppression, offering potential clinical advantages over enteric-coated esomeprazole. A fixed-dose combination (FDC) of proton pump inhibitors (PPIs) and antacid salts enables rapid acid suppression through the neutralizing effect of the antacid salt and the rapid absorption of PPIs. This study aimed to compare the pharmacokinetics (PKs) and pharmacodynamics (PDs) of a recently formulated FDC of esomeprazole and magnesium hydroxide to the enteric-coated esomeprazole in healthy subjects. A randomized, open-label, multiple-dose, two-treatment, two-way crossover design was conducted in healthy subjects. Forty-nine subjects were randomized to one of the two treatment sequences and received either the test drug (esomeprazole/magnesium hydroxide 40/350 mg) or reference drug (enteric-coated esomeprazole 40 mg) for 7 days in the first period and the alternative in the second period with a 14-day washout period. Blood samples were collected for up to 24 hours for PK assessment, and 24-hour gastric pH monitoring was conducted for PD assessment both before and after a single administration, as well as at a steady state after seven consecutive days of administration. The PK and PD parameters were compared between the two drugs. After multiple administrations, the median value of time to reach maximum concentration was faster in the test drug than in the reference drug, with a difference of 1.68 hours. The overall systemic exposure of the test drug was similar to that of the reference drug, and the PK parameter fell within the equivalence criteria. The test drug demonstrated a shorter time to reach gastric pH ≥ 4 compared to the reference drug (P = 0.0463). A decrease from baseline in integrated gastric acidity over 24 hours, which represents the degree of inhibition of gastric acid secretion, was equivalent between the two drugs. The fixed-dose combination of esomeprazole and magnesium hydroxide showed rapid absorption and quicker gastric acid suppression than enteric-coated esomeprazole with comparable PK and PD properties. ClinicalTrials.gov identifier: NCT04324905 (https://classic.clinicaltrials.gov/ct2/show/NCT04324905).

Background: Physiologically based pharmacokinetic (PBPK) modelling can assist in the development of drug therapies and regimens suitable for challenging patient populations such as very young children. This study describes a strategy employing PBPK models to investigate the intravenous use of the neuraminidase inhibitor oseltamivir in infants and neonates with influenza. Methods: Models of marmoset monkeys and humans were constructed for oseltamivir and its active metabolite oseltamivir carboxylate (OC). These models incorporated physicochemical properties and in vitro metabolism data into mechanistic representations of pharmacokinetic processes. Modelled processes included absorption, whole-body distribution, renal clearance, metabolic conversion of the pro-drug, permeability-limited hepatic disposition of OC and age dependencies for all of these processes. Models were refined after comparison of simulations in monkeys with plasma and liver concentrations measured in adult and newborn marmosets after intravenous and oral dosing. Then simulations with a human model were compared with clinical data taken from intravenous and oral studies in healthy adults and oral studies in infants and neonates. Finally, exposures after intravenous dosing in neonates were predicted. Results: Good simulations in adult marmosets could be obtained after model optimizations for pro-drug conversion, hepatic disposition of OC and renal clearance. After adjustment for age dependencies, including reductions in liver enzyme expression and renal function, the model simulations matched the trend for increased exposures in newborn marmosets compared with those in adults. For adult humans, simulated and observed data after both intravenous and oral dosing showed good agreement and although the data are currently limited, simulations in 1-year-olds and neonates are in reasonable agreement with published results for oral doses. Simulated intravenous infusion plasma profiles in neonates deliver therapeutic concentrations of OC that closely mimic the oral profiles, with 3-fold higher exposures of oseltamivir than those observed with the same oral dose. Conclusions: This work exemplifies the utility of PBPK models in predicting pharmacokinetics in the very young. Simulations showed agreement with a wide range of observational data, indicating that the processes determining the age-dependent pharmacokinetics of oseltamivir are well described.

Natural nanoparticles have been found to exist in traditional Chinese medicine (TCM) decoctions. However, whether natural nanoparticles can influence the oral bioavailability of active compounds has not been elucidated. Using Xie-Bai-San decoction (XBSD) as an example, the purpose of this study was to isolate, characterize and elucidate the mechanism of the nanoparticles (N-XBSD) in XBSD, and further to explore whether the bioavailability of the main active compounds could be enhanced by N-XBSD. N-XBSD were isolated from XBSD, and investigated its characterization and study of its formation mechanism, and evaluation of its ability to enhance bioavailability of active compounds. The N-XBSD was successfully isolated with the average particle size of 104.53 nm, PDI of 0.27 and zeta potential of -5.14 mV. Meanwhile, all the eight active compounds were most presented in N-XBSD. Kukoamine B could self-assemble with mulberroside A or liquiritin to form nanoparticles, respectively. And the FT-IR and HRMS results indicated the possible binding of the ammonium group of kukoamine B with the phenolic hydroxyl group of mulberroside A or liquiritin, respectively. The established UPLC-MS/MS method was accurate and reliable and met the quantitative requirements. The pharmacokinetic behaviors of the N-XBSD and decoction were similar in rats. Most notably, compared to that of free drugs, the , AUC , AUC , and MRT values of index compounds were the higher in N-XBSD, with a slower plasma clearance rate in rats. The major active compounds of XBSD were mainly distributed in N-XBSD, and N-XBSD was formed through self-assembly among active compounds. N-XBSD could obviously promote the bioavailability of active compounds, indicating natural nanoparticles of decoctions play an important role in therapeutic effects.

IntroductionCortex Periplocae has been demonstrated to possess a variety of pharmacological effects, particularly in the treatment of chronic heart failure, attributed largely to its cardiac glycosides particularly periplocin.MethodsIn order to gain a deeper understanding of the pharmacokinetic behaviors of periplocin and its metabolites, and to elucidate the influence of the cardiac glycoside extract matrix on their dynamic process in vivo , an ultra-performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-TQ-S-MS/MS) method was developed and successfully applied to a comparative pharmacokinetic study in rats following oral administration of either pure periplocin (50 mg/kg) or cardiac glycoside extract from Cortex Periplocae (100 mg/kg, equivalent to approximately 52 mg/kg periplocin).ResultsThe results showed that periplocin was absorbed rapidly in both groups (Tmax≤0.60 h). However, the extract matrix significantly altered the metabolic exposure. Compared with the periplocin group, the cardiac glycoside extract group demonstrated significantly higher levels of gomphogenin, with a marked increase in both Cmax and AUC(0-∞). Conversely, the systemic exposures AUC(0-∞) of periplocymarin and 17 α -asclepioside were significantly reduced. Furthermore, double peaks were observed in the concentration-time curves of gomphogenin and periplogenin, suggesting potential enterohepatic circulation.DiscussionThese findings reveal that the complex matrix alters the bioavailability of active metabolites, providing a crucial kinetic basis for optimizing clinical dosage regimens and safety monitoring of Cortex Periplocae .

PurposeSUVN-1105 is a novel formulation of abiraterone acetate which was developed to demonstrate improved bioavailability, compared to Zytiga and Yonsa, and to reduce the dose and eliminate the food effect. A Phase 1 study was conducted to assess the bioequivalence, food effect, and comparative pharmacokinetics of SUVN-1105 to Zytiga in healthy male subjects.MethodsThe study comprised of 2 segments. Segment 1 was a single-center, 4-period crossover, open-label, fixed treatment sequence, single-dose study to evaluate the safety and pharmacokinetics of SUVN-1105 (N = 12 subjects per period). Segment 2 was a single-center, open-label, single-dose, randomized, 4-period, 4-treatment, 4-sequence crossover study to evaluate bioequivalence and comparative pharmacokinetics of SUVN-1105 against Zytiga (N = 44) under overnight fasted, modified fasted, and fed conditions.ResultsAbiraterone exposures appeared to increase proportionately with SUVN-1105 dose (200 mg vs. 250 mg) in Segment 1. In Segment 2, abiraterone exposures of 250 mg SUVN-1105 in the fasted or fed conditions were higher than those of Zytiga 1000 mg in the overnight fasted conditions. Abiraterone exposures of 250 mg SUVN-1105 decreased in the fed conditions (64% and 29% decrease in Cmax and AUC, respectively) compared to overnight fasted conditions.ConclusionsThe abiraterone exposures of 250 mg SUVN-1105 in the fasted or fed conditions fall within the abiraterone exposures of 1000 mg Zytiga in fasted and modified fasted conditions. Single doses of SUVN-1105 were safe and well-tolerated in healthy males both in the fasted and fed conditions.

Silybin (SBN) is a major active constituent of silymarin, a mixture of flavonoids found in fruits and seeds of milk thistle. The aim of this study was to describe a simple bioanalytical method for quantifying SBN in rat plasma. A simple protein deproteinization procedure with acetonitrile (ACN) was employed for plasma sample preparation. A reversed column and gradient elution of a mobile phase (mixture of phosphate buffer (pH 5.0) and ACN) were used for chromatographic separation. The selectivity, linearity (50–5000 ng/mL), precision, accuracy, recovery, matrix effect, and stability for this method were validated as per the current Food and Drug Administration (FDA) guidelines. Our method for SBN was applied to a comparative pharmacokinetic study on four different commercial silymarin products. This in vivo rat study demonstrated that product #4 significantly enhanced the relative oral bioavailability of SBN, as compared to product #1–3. Therefore, the bioanalytical method proposed herein could serve as a promising alternative for preclinical pharmacokinetic studies on silymarin products and, by extension, clinical use after partial modification and validation.

Leuprolide is a synthetic nonapeptide drug (pyroGlu-His-Trp-Ser-Tyr-d-Leu-Leu-Arg-Pro-NHEt) that acts as a gonadotropin-releasing hormone agonist. The continuous administration of therapeutic doses of leuprolide inhibits gonadotropin secretion, which is used in androgen-deprivation therapy for the treatment of advanced prostate cancer, central precocious puberty, endometriosis, uterine fibroids, and other sex-hormone-related conditions. To improve the pharmacokinetic properties of peptide drugs, a fatty acid was conjugated with leuprolide for long-term action. In this study, we developed a simple ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous determination of leuprolide and leuprolide–oleic acid conjugate (LOC) levels. The developed method was validated in terms of linearity, precision, accuracy, recovery, matrix effect, and stability according to the US Food and Drug Administration guidelines, and the parameters were within acceptable limits. Subsequently, the pharmacokinetics of leuprolide and LOCs were evaluated. In vivo rat subcutaneous studies revealed that conjugation with fatty acids significantly altered the pharmacokinetics of leuprolide. After the subcutaneous administration of fatty-acid-conjugated leuprolide, the mean absorption time and half-life were prolonged. To the best of our knowledge, this is the first study showing the effects of fatty acid conjugates on the pharmacokinetics of leuprolide using a newly developed UPLC-MS/MS method for the simultaneous quantification of leuprolide and LOCs.

A sensitive and rapid ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) method was hereby developed for the determination of seven components, namely, glycyrrhizic acid, glycyrrhetinic acid, dehydrotumulosic acid, isoliquiritin, liquiritin, atractylenolide III, and cinnamic acid, in the plasma of rats after the oral administration of Ling-Gui-Zhu-Gan decoction (LGZGD). Besides, this very method was methodologically validated for specificity, linearity, inter-day and intra-day precision, accuracy, matrix effect, extraction recovery, and stability. It was also successfully used for the first time to compare the pharmacokinetic characteristics of the seven components after oral administration of LGZGD to normal rats and non-alcoholic fatty liver disease (NAFLD) rats. The results indicated significant differences between the pharmacokinetic characteristics of normal and NAFLD rats. To further reveal the different pharmacokinetic behaviors, the expressions of enzymes and transporters in the liver of normal and NAFLD rats were detected using UPLC-MS/MS. In the NAFLD rats, UDP-glucuronosyltransferase 1-1 (UGT1A1) and nine transporters were significantly inhibited and a positive correlation was observed between them and the AUC of the major components. The present results indicate that the pharmacokinetic differences between the normal and NAFLD rats might be attributed to the significant lower expression levels of both the metabolic enzyme UGT1A1 and nine transporter proteins in the NAFLD rats than in the normal rats. Meanwhile, UGT1A1 and the nine transporter proteins might be used as potential biomarkers to assess the ameliorative effect of LGZGD on NAFLD, which could provide useful information to guide the clinical application of LGZGD.

The administration of antiretrovirals (ARVs) for HIV pre-exposure prophylaxis (PrEP) is highly efficacious and may benefit from new long-acting (LA) drug delivery approaches. This paper describes a subcutaneous, reservoir-style implant for the LA delivery of tenofovir alafenamide (TAF) and documents the preclinical assessment of implant safety and pharmacokinetics (PK) in New Zealand White (NZW) rabbits (3 groups of n = 5), beagle dogs (2 groups of n = 6), and rhesus macaques (2 groups of n = 3). Placebo implants were placed in rabbits ( n = 10) and dogs ( n = 12). Implant parameters, including selection of the TAF form, choice of excipient, and PCL formulation were tuned to achieve targeted concentrations of the active anabolite of TAF, tenofovir diphosphate (TFV-DP), within peripheral blood mononuclear cells (PBMCs) and mucosal tissues relevant to HIV transmission. Sustained concentrations of TFV-DP in PBMCs over 100 fmol/10 6 cells were achieved in all animal species indicating that the implants effectively delivered TAF for 3–6 months. Unlike placebo implants without TAF, all active implants resulted in local adverse events (AEs) proximal to the implant ranging in severity from mild to moderate and included dermal inflammation and necrosis across all species. Despite these AEs, the implant performed as designed and achieved a constant drug release profile, supporting the continued development of this drug delivery platform.