Pharmacokinetic Parameters Research Articles

Levofloxacin activity at increasing doses in a murine model of fluoroquinolone-susceptible and -resistant tuberculosis.

High-dose levofloxacin was explored in a clinical trial against multidrug-resistant tuberculosis and failed to show increased efficacy. In this study, we used a murine model to explore the efficacy of a dose increase in levofloxacin monotherapy beyond the maximum dose evaluated in humans. A total of 120 4-week-old female BALB/c mice were intravenously infected with 106 CFU of Mycobacterium tuberculosis H37Rv wild-type (WT) or isogenic H37Rv mutants harboring GyrA A90V or D94G substitutions; the MICs were 0.25, 4, and 6 µg/mL, respectively. Levofloxacin 250 and 500 mg/kg were given every 12 h (q12h) orally for 4 weeks. Pharmacokinetic parameters were determined after five doses. These two regimens decreased lung bacillary load in mice infected with H37Rv WT but not in mice infected with the A90V and D94G mutants. Levofloxacin 250 mg/kg q12h in mice generated pharmacokinetic parameters equivalent to 1,000 mg/d in humans, whereas 500 mg/kg q12h generated a twofold greater exposure than the highest equivalent dose tested in humans (1,500 mg/d). In our dose-response model, the effective concentration at 50% (EC50) produced an AUC/MIC (AUC0-24h/MIC) ratio of 167.9 ± 27.5, and at EC80 it was 281.2 ± 97.3. Based on this model, high-dose levofloxacin regimens above 1,000 mg/d are not expected to cause a significant increase in bactericidal activity. This study suggests no benefit of high-dose levofloxacin above 1,000 mg/d in the treatment of fluoroquinolone-susceptible or -resistant tuberculosis.

Pharmacokinetics and bioequivalence of two formulations of mifepristone tablets in healthy Chinese subjects under fasting conditions: a single-center, open, randomized, single-dose, double-period, two-sequence, crossover trial.

A bioequivalence (BE) study was performed to evaluate the pharmacokinetics, safety, and bioequivalence of two formulations of mifepristone tablets in healthy Chinese volunteers under fasting conditions. A single-center, open, randomized, single-dose, double-period, two-sequence, crossover study in healthy subjects under fasting conditions was performed. The subjects received a single fasting dose of mifepristone (10mg/tablet) during the first and second periods, followed by a 14-day washout period, during which frequent pharmacokinetic (PK) sampling occurred up to 120h. The pharmacokinetic parameters of mifepristone were calculated based on the plasma drug concentration-time profile. Primary endpoints were the BE of major pharmacokinetic parameters (AUC0-t and AUC0-∞) and the maximum observed serum concentration (Cmax). Secondary endpoints were safety parameters. Forty subjects (34 male and 6 female subjects) were randomly assigned to treatment, with 39 completing the two-period study. After the single administration of mifepristone tablets (test preparation vs. reference preparation) under fasting conditions, the geometric mean ratios (GMRs) of Cmax, AUC0-t, and AUC0-∞ were 98.76%, 104.28%, and 104.83%, respectively. The primary metabolites of mifepristone (RU42633 and RU42698),the GMRs of Cmax, AUC0-t, AUC0-∞ were 102.33% and 100.97%, 103.17% and 103.71%, 104.02% and 103.84%, respectively. Similarly, for another metabolite of mifepristone (RU42698), the GMRs of Cmax, AUC0-t, and AUC0-∞ were 100.97%, 103.71%, and 103.84%, respectively. All 90% confidence intervals (CIs) for the test/reference AUC ratio and Cmax ratio were within the acceptable range (80%-125%) for BE, which met the requirements of bioequivalence. No serious adverse events (AEs) occurred, and all AEs were classified as level 1 or 2. The PK parameters of mifepristone and its metabolites (RU42633 and RU42698) were measured using the (GMRs) of AUC0-t, AUC0-∞, and Cmax and were similar between the test and reference drug. The two formulations of mifepristone showed good tolerability and a similar safety profile. chinadrugtrials.org.cn, identifier CTR20182413.

Obesity-related drug transporter expression alterations in human liver and kidneys

BackgroundPathophysiological changes associated with obesity might impact various drug pharmacokinetics (PK) parameters. The liver and kidneys are the primary organs involved in drug clearance, and the function of hepatic and renal transporters is critical to efficient drug elimination (or reabsorption). Considering the impact of an increased BMI on the drug’s PK is crucial in directing dosing decisions. Given the critical role of transporters in drug biodisposition, this study investigated how overweight and obesity affect the gene expression of renal and hepatic drug transporters.MethodsHuman liver and kidney samples were collected post-mortem from 32 to 28 individuals, respectively, which were divided into the control group (lean subjects; 18.5 ≤ BMI < 25 kg/m2) and the study group (overweight/obese subjects; BMI ≥ 25 kg/m2). Real-time quantitative PCR was performed for the analysis of 84 drug transporters.ResultsOur results show significant changes in the expression of genes involved in human transporters, both renal and hepatic. In liver tissue, we found that ABCC4 was up-regulated in overweight/obese subjects. In kidney tissue, up-regulation was only observed for ABCC10, while the other differentially expressed genes were down-regulated: ABCA1, ABCC3, and SLC15A1.ConclusionsThe observed alterations may be reflected by the differences in drug PK between lean and obese populations. However, these findings need further evaluation through the proteomic and functional study of these transporters in this patient population.

Pharmacokinetics and Safety of a Novel Extended-Release Microsphere Formulation of Risperidone in Patients with Schizophrenia or Schizoaffective Disorder.

Risperidone extended-release injectable suspension (R-ERIS; marketed as RYKINDO) is a novel immediate-release version of risperidone formulated as extended-release microspheres for biweekly intramuscular injection to treat schizophrenia in adults. The pharmacokinetics (PK) and safety of R-ERIS were evaluated in a multicenter, randomized, open-label, multiple-dose study in patients with stable schizophrenia or schizoaffective disorder. Eligible patients (N = 108) 18 to 65 years old were randomized (1:1) to receive IM injections of R-ERIS 25 mg or the comparator, a biweekly risperidone long-acting injectable (BW-RLAI; marketed as RISPERDAL CONSTA) 25 mg for a total of 5 injections. The primary objective was to evaluate the relative bioavailability of active moiety (risperidone plus 9-hydroxyrisperidone) at steady state. Blood samples were analyzed for risperidone and 9-hydroxyrisperidone using a validated, specific, and sensitive liquid chromatography with tandem mass spectrometry method. Plasma concentration-time data were analyzed using non-compartmental methods. Pharmacokinetic parameters were calculated based on individual patient PK profiles. Safety was assessed using standard measures. At steady state, mean plasma concentrations of the active moiety were similar for R-ERIS and BW-RLAI. R-ERIS rapidly released risperidone after the injection without apparent lag time. Plasma active moiety levels reached steady state after the second injection of R-ERIS. The elimination of the drug was completed approximately 2weeks earlier for R-ERIS as compared to that for BW-RLAI. R-ERIS was safe and well tolerated. Overall, R-ERIS exhibited a faster onset and offset than BW-RLAI and statistical analysis of exposure parameters demonstrated bioequivalence at steady state.

Discriminative Power of the Flow through Cell Dissolution Tester in Predicting the In Vivo Performance of Pentoxifylline SR Product under Fed and Fasting Conditions

This study explored, for the first time the role of different designs of the Flow-Through-Cell (FTC, USP IV) dissolution Tester in predicting the in-vivo performance of Pentoxifylline (PTX) sustained-release (SR) market product, under fed & fasting conditions. Release studies of Trental® SR 400 mg (Sanofi, Egypt), were carried-out in the FTC under different conditions, including: different volumes / compositions of release media, variable FTC flow patterns as well as applying open / closed loop configuration setups. Pharmacokinetic (PK) data, obtained from literature, were converted to in-vivo fraction-absorbed [FA] using Wagner-Nelson (WN) method. A 1:1 IVIVC was investigated by comparing PTX fraction-dissolved [FD] under different FTC release designs versus calculated [FA]. Predicted PK parameters were evaluated, and compared with actual data, with estimation of prediction-error (PE%). The suggested FTC design; a closed-loop setup, with turbulent-flow pattern of the dissolution medium; provided the most acceptable PTX release according to USP labeled limits (USP 27). Also, results showed that PTX release was pronouncedly increased in a finite-volume of gradient-buffer system rather than water, which guarantee complete resemblance to GIT environment. This release design presented the most predictive IVIVC model with PTX in-vivo performance under fasting / fed states, with acceptable PE% values in terms of Cmax and AUCs. A suggested FTC design is proposed as an alternative dissolution model in the official USP-monograph for PTX SR products.Graphical

Pharmacokinetic interaction between single and multiple doses of darunavir, in combination with cobicistat or ritonavir, and single-dose dabigatran etexilate in healthy adults

ObjectiveDarunavir (DRV) is a P-glycoprotein (P-gp) inhibitor. Dabigatran etexilate, prodrug of the anticoagulant dabigatran, is a P-gp probe substrate. This study evaluated the effect of single and multiple doses of DRV, coadministered with cobicistat (COBI) or ritonavir (rtv), on the pharmacokinetics (PK) of single-dose dabigatran etexilate.MethodsThis was an open-label, fixed-sequence, single-center, 2-panel, phase 1 study in which healthy adult participants were equally divided over 2 panels. In panel 1, participants received single and multiple doses of DRV/COBI 800/150 mg coadministered with single-dose dabigatran etexilate 150 mg. In panel 2, participants received single and multiple doses of DRV 800 mg + rtv 100 mg coadministered with single-dose dabigatran etexilate 150 mg. Key PK parameters evaluated were maximum plasma concentration (Cmax) and area under the plasma concentration-time curve from time zero to infinity (AUCinf) for free and total dabigatran.ResultsOverall, 28 participants were enrolled and treated (n = 14 per panel). Dabigatran Cmax and AUCinf increased 2.64-fold after a single dose of DRV/COBI and 1.99- and 1.88-fold, respectively, after multiple doses of DRV/COBI. Dabigatran Cmax and AUCinf increased 1.64- and 1.72-fold, respectively, after a single dose of DRV + rtv and 1.22- and 1.18-fold, respectively, after multiple doses of DRV + rtv. In both panels, the most commonly reported adverse events were diarrhea and headache.ConclusionFindings of increased dabigatran exposure with DRV/COBI or DRV + rtv coadministration indicate an inhibitory effect of single-dose boosted DRV on P-gp, and a mixed inhibitory/inductive effect of multiple doses of boosted DRV on P-gp.Trial registrationClinicalTrials.gov, NCT04208061. Registered December 19, 2019

Drug-Drug Interaction Between Dihydroartemisinin-Piperaquine and Sulfadoxine-Pyrimethamine During Malaria Chemoprevention in Pregnant Women.

Co-administration of dihydroartemisinin-piperaquine (DP) and sulfadoxine-pyrimethamine (SP) for intermittent preventive treatment of malaria in pregnancy (IPTp) may be superior in preventing adverse birth outcomes compared with either therapy alone, but potential drug-drug interactions require investigation. We conducted intensive and sparse pharmacokinetic (PK) studies in a subset of Ugandan women participating in a randomized controlled trial of monthly IPTp with SP vs. DP vs. DP + SP. Intensive PK sampling was performed from day 0 to 23 after dosing at 28 weeks gestation in 87 participants across treatment arms. Sparse sampling was performed on day 28 (trough) after dosing at 20 and 28 gestational weeks in additional 196 participants receiving SP vs. DP + SP. Intensive PK analysis demonstrated that compared with SP alone, co-administration of DP + SP was associated with lower maximal concentrations, the area under the concentration-time curves (AUC), and day 23 concentrations of sulfadoxine (25%, 25%, and 27%) and pyrimethamine (26%, 34%, and 32%) (P < 0.05 for all comparisons). Sparse PK results demonstrated participants co-administered DP + SP had lower trough concentrations after dosing at 20 and 28 gestational weeks for sulfadoxine (6%, P = 0.68 and 31%, P = 0.023, respectively) and pyrimethamine (18%, P = 0.032 and 33%, P < 0.001, respectively) compared with SP alone. Co-administration of DP + SP was associated with a 19% reduction in piperaquine AUC (P = 0.046), but no significant difference in other PK parameters compared with DP alone. In summary, co-administration of DP + SP was associated with significantly reduced SP exposure, with a greater magnitude during the third vs. second trimester. The clinical consequences of this interaction are yet unknown.

Biocompatible cationic 5-fluorouracil loaded elastic liposomes for ocular delivery: In vitro, ex vivo, and in vivo evaluation

5-fluorouracil (5-FU) is used to treat scleral and episcleral fibroblast proliferations (scarring process) in the eyes. Frequent washing of the conventional solution results in limited drug access to the eyes. Taguchi and central composite design (CCD) oriented optimized mucoadhesive cationic elastic liposomes were prepared and characterized. The optimized F-CEL8 (composed of 85 mg of dipalmitoyl-phosphatidylcholine, 15 mg of sodium cholate, 10 mg of 5-FU, 7 mg of ethanol, and 883 mg of buffer) and its gel were studied for in vitro and ex vivo drug release profiles as compared to the drug solution and the liposomes. In vitro hemolysis and Draize studies corroborated safety concerns. An in vivo pharmacokinetics study was studied in rats. Each mL of F-CEL8 contained dipalmitoyl-phosphatidylcholine (X1), sodium cholate, and ethanol to deliver 10 mg of 5-FU with optimal vesicle size, low polydispersity index (PDI), and high zeta potential (ZP). The %EE value of spherical F-CEL8 was quite high (82.3 ± 7.1 %) as compared to liposomes (∼53 %) due to the large volume of the inner aqueous chamber of vesicles. F-CEL8-gel exhibited relatively high viscosity for slow and sustained release for 24 h as compared to others. The percent permeation of 5-FU from the solution, F-CEL8, F-CEL8-gel, and the liposomes were found to be 28.6 ± 4.6 %, 69.6 ± 7.4 %, 76.89 ± 12.4 %, and 54.8 ± 5.3 %, respectively. All isotonic formulations did not exhibit hemolysis and irritation to the eyes. The gel illustrated the highest values of pharmacokinetics parameters as compared to the solution and the liposomes, which may be attributed to the maximum residence time achieved through electrostatic interaction (the vesicle internalization with the mucosal layer of eyes).

Linezolid Pharmacokinetics in Critically Ill Patients: Continuous Versus Intermittent Infusion.

Linezolid has been found to have considerable interindividual variability, especially in critically ill patients, which can lead to suboptimal plasma concentration. To overcome this shortcoming, several solutions have been proposed. These include using loading dose, higher maintenance doses, and dose stratification according to the patient's particularities, therapeutic drug monitoring, and drug administration via continuous infusion (CI) instead of intermittent infusion (II). In the present study, we aim to compare the pharmacokinetic (PK) parameters of linezolid after administration as II versus CI to critically ill patients. In a prospective study conducted in an intensive care unit, we compared the same two daily doses of linezolid administered via II versus CI. The serum concentration was measured, and pharmacokinetic parameters were calculated. The pharmacokinetic/pharmacodynamic (PK/PD) indices for efficacy chosen were area under the concentration-time curve at steady state divided by the minimum inhibitory concentration over 80 (AUC24-48/MIC > 80). Greater serum concentration variability was observed in the II group than in the CI group. The %T > MIC > 80% was achieved for MICs of 1 and 2 µg/mL 100% of the time, whereas for the II group, this was 93% and 73%, respectively. AUC24-48/MIC > 80 was reached in 100% of cases in the CI group compared with 87% in the II group for a MIC of 1 µg/mL. The two infusion methods may be used comparably, but utilizing CI as an alternative to II may have potential benefits, including avoiding periods of suboptimal concentrations, which may enhance safety profiles and clinical outcomes. Considering the relatively few studies performed on linezolid to date, which are increasing in number, the results of the present study may be of interest.

Affordable and Reliable RP-HPLC Method for Verapamil Hydrochloride Quantification in Rabbit Plasma for Pharmacokinetics

Background: Existing bioanalytical methods for verapamil hydrochloride (VH) are often complex, requiring advanced instrumentation and specialized expertise, which limits their use in resource-constrained laboratories. Aim: The goal of this study is to fill this gap by developing a simplified, robust RP-HPLC-UV approach for the estimation of verapamil hydrochloride in rabbit plasma. Designed to enhance accuracy and precision while minimizing sample preparation challenges, this method addresses existing limitations by providing an affordable and reliable alternative for laboratories lacking sophisticated instrumentation. Methods: The bioanalytical method was implemented on C-18 stationary phase (5 μ, 250 × 4.6 mm) using acetonitrile/0.1% tetrahydrofuran (THF) in water (80:20, in volume) as the liquid system at a 1 mL/min flow speed, employing carvedilol as an internal standard. Results: The reported retention times of verapamil hydrochloride and carvedilol were ~7.64 and 4.69 min, respectively, at sufficiently high system suitability standards. The linearity of the bioanalytical approach can be seen between 0.025 and 5.0 µg/mL (r2 = 0.9991). The findings indicated that there was no matrix influence in terms of accuracy (≥98.96 ± 2.68%), intra- and inter-day precision (≤3.68%), recovery (101.98 ± 2.76%), and procedure efficiency (100.65 ± 1.82%). Benchtop, long-term, and short-term stability investigations all revealed that the verapamil hydrochloride in the bio-samples was stable. The pharmacokinetic parameters (Cmax—3.47 µg/mL; Tmax—1.59 h) were studied from time-dependent plasma concentrations of verapamil hydrochloride estimated after 40 mg oral dosing in New Zealand white rabbits. Conclusions: The developed bioanalytical method provided easier quantitative analysis of verapamil hydrochloride from rabbit plasma and was effectively used in a pharmacokinetic investigation of an oral bolus. The reliable performance of this method under practical conditions positions it as a crucial tool for advancing pharmacokinetic studies across various research environments.

Are We Dosing Correctly? Population Pharmacokinetics of Cefepime in Critically Ill Pediatric Patients

Abstract Background Dosing guidelines of cefepime are well defined in healthy pediatric and adult populations but have not been extensively studied in critically ill pediatric patients. Patients who are critically ill may have significant alterations in antibiotic pharmacokinetics (PK) and pharmacodynamics (PD) due to many factors. Receipt of ECMO or CRRT may further alter PK/PD due to changes in clearance and volume of distribution and the depletion of plasma proteins. Since critically ill pediatric patients are likely to receive multiple courses of antimicrobials, optimization of drug dosing and delivery is critically important for individual patient outcomes. This study will test the hypothesis that the PK of cefepime is substantially altered in critically ill pediatric patients. Methods We prospectively enrolled patients in VUMC pediatric ICUs receiving cefepime, including those receiving ECMO or CRRT. Plasma samples were collected at opportune timepoints enriched for specific PK/PD metrics. Cefepime plasma concentrations were measured by LC-MS/MS. Weight, dose, interval, and administration time were extracted from the medical record. Monolix was used to fit population PK models using one and two-compartment models with a proportional error model. Covariate modeling was performed with a priori selected covariates: ECMO, CRRT, sex, race, ethnicity, gestational age, and creatinine clearance (CrCl). The final covariate model was used to perform probability of target attainment (PTA) analysis using Monte Carlo simulation. 6,000 subjects were simulated for each dosing regimen, with 3 weight categories (≤9 kg, 9-25 kg, and &amp;gt;25 kg) and 2 CrCl categories (≤90 mL/min and &amp;gt;90 mL/min). PTA was calculated over a grid of possible MIC values based on three targets, 65% fT&amp;gt;MIC, 100% fT&amp;gt;MIC, and 100% fT&amp;gt;4×MIC. Results Preliminary data from 84 pediatric participants receiving cefepime were analyzed. Of these, 9 received CRRT and 10 received ECMO. An average of 3 samples were collected per participant. A two compartment with proportional error model was selected as the base model. Population PK parameter estimates for the base model, base model with weight, and final covariate model were calculated. Inclusion of weight and CrCl significantly improved model fit. CRRT, ethnicity, and gestational age did significantly improve model fit, but their inclusion in the model did not provide evidence of being significantly better than the model with only weight and CrCl. The results from the PTA analysis are seen in Figure 1. We observed an overall ordering of PTA by dosing regimen across all three targets, with q8h 3-hour infusion having the highest PTA and q12h 30-minute infusion having the lowest PTA. Increased CrCl led to reduced PTA and as weight increased, PTA also increased. Conclusion This study will be among the first and largest to characterize cefepime PK in the critically ill pediatric population. Clinicians should incorporate local antibiograms with these population PK models to determine optimal dosing in critically ill pediatric patients. The use of extended infusions may be beneficial for PK/PD target achievement, particularly for resistant pathogens. Since clinical covariates affect PK parameters, this population may also benefit from therapeutic drug monitoring. Figure 1. Comparison of PTA among four dosing regimens of cefepime at targets of 65% fT&amp;gt;MIC, 100% fT&amp;gt;MIC, and 100% fT&amp;gt;4×MIC.

Population pharmacokinetics and pharmacodynamics of L-asparaginase and its impact on the development of pancreatitis and hypersensitivity reactions in children with leukemia under treatment

L-asparaginase (L-Asp) is an essential enzyme in the treatment of patients with Acute Lymphoblastic Leukemia (ALL), commonly associated with adverse events (AE). Knowing the pharmacokinetic and pharmacodynamic (PK/PD) parameters of L-Asp as well as its relationship with the development of AE is an important strategy in the search to improve the efficacy and safety of the treatment. Seventy-four children with ALL that were being treated with L-Asp, were included. One to three blood samples were randomly obtained from each patient, at times from 0 to 30 hours, until completing a total of 211 samples. The L-Asp activity and the Asparagine (Asp) concentration were quantified, in addition, the presence of anti-L-Asp antibodies (Anb) was determined. A population PK/PD model of L-Asp was developed to determine the association of covariates with PK/PD parameters. The presence of Anb was associated with the increase in L-Asp clearance (CL) and with the decrease of volume of distribution 1 (V1). On the other hand, female sex was significantly associated with the increase of V1, while the age from 1 to 6 years was significantly associated with the increase of V1. The presence of Anb as well as the female sex were related to the increase IC50 (concentration-needed to deplete-50% of Asp). Patients who presented Asp depletion before the first 24 hours after administration presented pancreatitis, this could be a risk marker. Significant results were found in this study, use of these results may contribute to the safe and effective use of L-Asp.

Investigation of ponatinib metabolism and drug-drug interactions with lycopene and shikonin in vitro and invivo

Ponatinib is approved for use in patients with chronic myeloid leukemia (CML) who are resistant to or intolerant to prior tyrosine kinase inhibitor (TKI) therapy. Given that ponatinib can induce significant cardiotoxicity when taken, and that most Chinese medicines have cardioprotective effects, it is possible to administer them in combination in clinic to alleviate adverse effects. The quantitative determination of ponatinib and its metabolite N-desmethyl ponatinib was optimized and fully verified by ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). And the drug-drug interactions (DDI) of ponatinib with lycopene and shikonin, both in vivo and in vitro, were studied. The results of bioanalytical methodology showed that ponatinib and N-desmethyl ponatinib had good linearity in plasma samples, and their selectivity, accuracy, precision, stability, matrix effect and recovery were all satisfied with the need of quantitative analysis of samples. In animal experiments, compared with the control group, lycopene and shikonin significantly changed the pharmacokinetic parameters of ponatinib, including AUC(0-t), AUC(0-∞) and CLz/F, while having no effect on the pharmacokinetic parameters of N-desmethyl ponatinib. In vitro interaction studies indicated that lycopene showed mixed inhibition mechanism on ponatinib metabolism in both rat liver microsomes (RLM) and human liver microsomes (HLM). And, shikonin displayed mixed inhibition mechanism in RLM and competitive inhibition mechanism in HLM, respectively. In summary, the UPLC-MS/MS method can accurately and sensitively quantify ponatinib and N-desmethyl ponatinib, and provide further reference for clinical drug combination between ponatinib and lycopene or shikonin.

Edoxaban pharmacokinetics during in vitro continuous renal replacement therapy

BackgroundTo evaluate the clearance of edoxaban during modeled in vitro continuous renal replacement therapy (CRRT), assess protein binding and circuit adsorption, and provide initial dosing recommendations.MethodsEdoxaban was added to the CRRT circuit and serial pre-filter bovine blood samples were collected along with post-filter blood and effluent samples. All experiments were performed in duplicate using continuous veno-venous hemofiltration (CVVH) and hemodialysis (CVVHD) modes, with varying filter types, flow rates, and point of CVVH replacement fluid dilution. Concentrations of edoxaban and urea were quantified via liquid chromatography-tandem mass spectrometry. Plasma pharmacokinetic parameters for edoxaban were estimated via noncompartmental analysis. Two and three-way analysis of variance (ANOVA) models were built to assess the effects of mode, filter type, flow rate, and point of dilution on CLCRRT. Linear regression was utilized to provide dosing estimations across CRRT effluent flow rates from 0.5 to 5 L/h. Optimal edoxaban doses were suggested using CLCRRT and population non-renal clearance (CLNR) to estimate total clearance and match the systemic AUC associated with efficacy in the treatment of venous thromboembolism.ResultsEdoxaban clearance from the CRRT circuit occurred primarily via hemofilter adsorption to the HF1400 and M150 filters at 74% and 65%, respectively, while mean percent protein binding was 41%. Multivariate analyses confirmed the lack of influence of CRRT mode, filter type, and point of dilution on the CLCRRT of edoxaban allowing dosing recommendations to be made based on effluent flow rate. Edoxaban doses of 30-45 mg once daily were estimated to achieve target the AUC threshold for flow rates from 0.5 to 5 L/h.ConclusionFor CRRT flow rates most employed in clinical practice, an edoxaban dose of 45 mg once daily is predicted to achieve target systemic exposure thresholds for venous thromboembolism treatment. The safety and efficacy of this proposed dosing warrants further investigation in clinical studies.

Formulation development, characterization, and evaluation of sorafenib-loaded PLGA-chitosan nanoparticles.

The basic purpose of this work was to develop environmentally friendly, biodegradable, and biocompatible polymeric nanoparticles of sorafenib that can effectively release the desired drug in a customized and controlled manner for targeting hepatocellular carcinoma. The solvent evaporation technique was employed for the synthesis of sorafenib-loaded PLGA-chitosan nanoparticles, followed by various experimental specifications and compatibility studies using poloxamer 407 as the stabilizer. The best nanoparticles thus synthesized were selected to be used for cytotoxicity investigations through in vitro and in vivo assessments. For the in vitro drug release tests, the dialysis bag diffusion technique was used. For both chitosan nanoparticles and PLGA loaded with sorafenib, a biphasic release pattern was found, exhibiting a protracted release lasting 10 days after a 24-h burst release. As experimental animals, rabbits were utilized to evaluate different in vivo pharmacokinetic properties of the selected formulations. Plasma samples were extracted with acetonitrile and analyzed through the developed HPLC method. Pharmacokinetic parameters such as AUC0-t, Cmax MRT, Vd, and half-life (t1/2) were enhanced significantly (p ≤ 0.001), while clearance was considerably decreased (p ≤ 0.001) for the chosen synthesized nanoparticles in contrast to the commercially accessible sorafenib formulation (Nexavar®). The cytotoxicity of the reference drug and sorafenib-loaded PLGA and chitosan nanoparticles was calculated by performing an MTT assay against HepG2 cell lines. The developed polymeric sorafenib nanoformulations possess the appropriate physicochemical properties, better targeting, surface morphology, and prolonged release kinetics. The pharmacokinetic parameters were improved significantly when the results were compared with commercially available sorafenib formulations.

Comprehensive Pharmacokinetic Evaluation of High Melanin Binder Levofloxacin in Rabbits Shows Potential of Topical Eye Drops for Posterior Segment Treatment.

The purpose of this work was to understand the impact of melanin binding on ocular pharmacokinetics after administration of a high-binder model drug via different administration routes. We applied levofloxacin to pigmented and albino rabbits as eye drops (single and multiple), as well as by intravitreal and intravenous injections. Ocular tissues and plasma were analyzed for levofloxacin concentrations with liquid chromatography-mass spectrometry (LC-MS/MS), and pharmacokinetic parameters were calculated. The data show enrichment of levofloxacin and weeks-long retention in pigmented tissues. Upon intravitreal injection, the area under the curve (AUC) values in pigmented tissues were about 9 to 15 times higher than the respective values in the albino rabbits, but this difference expanded to 255- to 951-fold following topical eye drop administration. Multiple dosing of eye drops led to substantial accumulation of levofloxacin in the pigmented tissues: AUC values were 3 to 12 times higher than after intravitreal injection. The AUCs were much lower after single topical or intravenous drug administrations. High drug levels (0.1-35 µM) were always observed in the neural retinas of pigmented eyes; the highest exposure was seen after intravitreal administration followed by multiple doses of topical drops. Single topical instillation and intravenous injections to the albino rabbits resulted in vitreal bioavailability values of 0.009% and 0.003%, respectively. Melanin binding can be used to achieve targeted drug delivery and extended retention in pigmented ocular tissues. The results from topical multiple dosing experiments suggest that eye drop treatment may yield drug exposures and responses comparable to intravitreal delivery, even in the retinal pigment epithelium and choroid.

Recent Advancements in Cancer RNA-interference Therapy with Nanotechnology Strategies

Cancer is a global challenge, and genetics play a major role in onsets and in designing the next generation of cancer therapies. One of the key approaches is the downregulation of genes through RNA interference (RNAi) which has been proposed as a promising tool for controlling cancer-causing genes by employing a complementary base-pairing mechanism. Crucial tools in RNAi; small interfering RNA (siRNA), and microRNA (miRNA) have been extensively utilized in cancer therapy. Despite their discovery nearly two decades ago, only a handful of RNAi-based products have recently gained approval from regulatory authorities like the FDA, principally due to inherent limitations. The efficacy of RNAi therapies is significantly hindered by barriers related to absorption, distribution, metabolism, and excretion, leading to rapid elimination from the systemic circulation before reaching the cytosol of targeted cells. Nevertheless, RNAi therapeutics hold immense promise in various diseases, especially in various types of cancer. Overcoming these challenges demands the design of suitable drug delivery systems and the implementation of strategies aimed at enhancing pharmacokinetic parameters associated with RNAi therapies. Nanotechnology-based vehicles such as polymer-based nanoparticles, lipid nanoparticles, liposomes, dendrimers, and inorganic nanoparticles may serve as efficient carriers for targeting RNAi therapies to their desired sites. This review discusses the recent advances in nanotechnology strategies for RNAi delivery, with the overarching objective of facilitating effective targeting and gene silencing for the advancement of RNAi in cancer therapy.

Impacts of age and BMI on vancomycin model choice in a Bayesian software: Lessons from a very large multi-site retrospective study.

Model-informed precision dosing (MIPD) optimizes drug doses based on pharmacokinetic (PK) model predictions, necessitating careful selection of models tailored to patient characteristics. This study evaluates the predictive performance of various vancomycin PK models across diverse age and BMI categories, drawing insights from a large multi-site database. Adults receiving vancomycin intravenous therapy at United States health systems between January 1, 2022, and December 31, 2023, were included. Patient demographics, vancomycin administration records, and therapeutic drug monitoring levels (TDMs) were collected from the InsightRX database. Age and body mass index (BMI)-based subgroups were formed to assess model performance, with predictions made iteratively. The optimal model for each age-BMI subgroup was chosen based on predefined criteria: models were filtered for mean percentage error (MPE) ≤ 20% and normalized root mean squared error (RMSE) < 8 mg/L, and then the most accurate among them was selected. A total of 384,876 treatment courses across 155 US health systems were analyzed, contributing 841,604 TDMs. Eleven models were compared, showing varying accuracy across age-BMI categories (41%-73%), with higher accuracy observed once TDMs were available for Bayesian estimates of individual PK parameters. Models performed more poorly in younger adults compared to older adults, and the optimal model differed depending on age-BMI categories and prediction methods. Notably, in the a priori period, the Colin model performed best in adults aged 18-64 years across most BMI categories; the Goti/Tong model performed best in the older, non-obese adults; and the Hughes model performed best in many of the obese categories. Our study identifies specific vancomycin PK models that demonstrate superior predictions across age-BMI categories in MIPD applications. Our findings underscore the importance of tailored model selection for vancomycin management, especially highlighting the need for improved models in younger adult patients. Further research into the clinical implications of model performance is warranted to enhance patient care outcomes.

Application of machine-learning models to predict the ganciclovir and valganciclovir exposure in children using a limited sampling strategy.

Intravenous ganciclovir and oral valganciclovir display significant variability in ganciclovir pharmacokinetics, particularly in children. Therapeutic drug monitoring currently relies on the area under the concentration-time (AUC). Machine-learning (ML) algorithms represent an interesting alternative to Maximum-a-Posteriori Bayesian-estimators for AUC estimation. The goal of our study was to develop and validate an ML-based limited sampling strategy (LSS) approach to determine ganciclovir AUC0-24 after administration of either intravenous ganciclovir or oral valganciclovir in children. Pharmacokinetic parameters from four published population pharmacokinetic models, in addition to the World Health Organization growth curve for children, were used in the mrgsolve R package to simulate 10,800 pharmacokinetic profiles of children. Different ML algorithms were trained to predict AUC0-24 based on different combinations of two or three samples. Performances were evaluated in a simulated test set and in an external data set of real patients. The best estimation performances in the test set were obtained with the Xgboost algorithm using a 2 and 6 hours post dose LSS for oral valganciclovir (relative mean prediction error [rMPE] = 0.4% and relative root mean square error [rRMSE] = 5.7%) and 0 and 2 hours post dose LSS for intravenous ganciclovir (rMPE = 0.9% and rRMSE = 12.4%). In the external data set, the performance based on these two sample LSS was acceptable: rMPE = 0.2% and rRMSE = 16.5% for valganciclovir and rMPE = -9.7% and rRMSE = 17.2% for intravenous ganciclovir. The Xgboost algorithm developed resulted in a clinically relevant individual estimation using only two blood samples. This will improve the implementation of AUC-targeted ganciclovir therapeutic drug monitoring in children.

Pharmacokinetic analysis and simplified uptake measures for tumour lesion [18F]F-AraG PET imaging in patients with non-small cell lung cancer.

The novel positron emission tomography (PET) imaging tracer, [18F]F-AraG, targets activated T-cells, offering a potential means to improve our understanding of immune-oncological processes. The aim of this study was to determine the optimal pharmacokinetic model to quantify tumour lesion [18F]F-AraG uptake in patients with non-small cell lung cancer (NSCLC), and to validate simplified measures at different time intervals against the pharmacokinetic uptake parameter. Ten patients with early-stage NSCLC and three patients with advanced NSCLC underwent a dynamic PET scan of minimal 60min. Venous and/or arterial blood sampling was obtained at maximum seven time points. Tumour lesion time activity curves and metabolite-corrected input functions were analysed using single-tissue reversible (1T2k), two-tissue irreversible (2T3k) and two-tissue reversible (2T4k) plasma input models. Simplified uptake measures, such as standardised uptake value (SUV) and tumour-to-blood (TBR) or tumour-to-plasma ratio (TPR), were evaluated for different time intervals. Whole-blood and plasma radioactivity concentrations showed rapid clearance of [18F]F-AraG. Metabolite analysis revealed a low rate of metabolism, at 70min p.i., on average, 79% (SD = 9.8%) of the total radioactivity found in blood corresponded to intact [18F]F-AraG. The time activity curves were best fitted by the 2T3k model. Strong positive correlations were found for SUV (body weight (BW), lean body mass (LBM) or body surface area (BSA) corrected), TBR and TPR for any time interval between 20 and 70min p.i. against the 2T3k-derived Ki. The correlation of TBR at 60-70min p.i. with 2T3K-derived Ki (r (df = 20) = 0.87, p < 0.01), was stronger than for SUVBW (r (df = 20) = 0.80, p < 0.01). Tumour lesion [18F]F-AraG uptake in patients with NSCLC is characterised by a 2T3k model. TBR and TPR show most potential for simplified quantification of tumour lesion [18F]F-AraG uptake in patients with NSCLC.