National reflection on organs-on-chip for drug development: New regulatory challenges.

Organs-on-chip (OoC) are innovative and promising in vitro models, particularly in the process of developing new drugs, to improve predictivity of preclinical studies in humans. However, a lack of regulatory consensus on acceptance criteria and standards around these technologies currently hinders their adoption and implementation by end-users. A reflection has been conducted at the National Agency for Medicines and Health products safety (ANSM) in order to address this issue, which has gained momentum at the international level in recent years. If the subject of OoC is of international interest, France is also in the process of structuring an OoC network, in order to best support the emergence of this new technological innovation. Focusing on liver-on-a-chip, the authors drafted a first list of regulatory requirements to help standardize these devices and their use. Technological and biological relevance of liver-on-a-chip was also evaluated, in comparison with current in vitro and in vivo models, based on the available literature. The authors offer an analysis of the current scientific and regulatory situation, highlighting the key regulatory issues for the future.

Pharmacokinetics of intact lipid nanocapsules using new quantitative FRET technique.

The present study investigated the pharmacokinetics of intact lipid nanocapsules (LNCs) after intravenous administration in rats. Six different Förster resonance energy transfer LNCs (FRET-LNCs) have been studied with 2 sizes (50 and 85 nm) and 3 coating types (none, DSPE-mPEG 2000 or stearylamine). A FRET-LNCs blood extraction method was developed to retain an accurate FRET signal. Intact FRET-LNCs were specifically quantified through combination of FRET signal and Nano Tracker Analysis. Pharmacokinetic data were first described by non-compartmental analysis, then used to develop a population pharmacokinetic model. The pharmacokinetic elimination of FRET-LNCs was non-linear and dependent on size and surface modification, while the distribution was dependent on size. The LNCs 85 nm volume of distribution was lower than LNCs 50 nm. As expected, LNCs 85 nm with PEG coating displayed a lower clearance than other formulations. Surprisingly, this study highlighted a faster elimination of LNCs 50 nm with PEG compared to other formulations which could be explained by instability in blood. This first pharmacokinetic model of intact LNCs allowed a thorough understanding of the influence of size and coating on pharmacokinetic properties and paves the way for future mechanistic modeling approaches to predict the fate of LNCs in vivo.

Impact of pharmacogenetics on variability in exposure to oral vinorelbine among pediatric patients: a model-based population pharmacokinetic analysis.

PURPOSE: Better understanding of pharmacokinetics of oral vinorelbine (VNR) in children would help predicting drug exposure and, beyond, clinical outcome. Here, we have characterized the population pharmacokinetics of oral VNR and studied the factors likely to explain the variability observed in VNR exposure among young patients. DESIGN/METHODS: We collected blood samples from 36 patients (mean age 11.6 years) of the OVIMA multicentric phase II study in children with recurrent/progressive low-grade glioma. Patients received 60 mg/m2 of oral VNR on days 1, 8, and 15 during the first 28-day treatment cycle and 80 mg/m2, unless contraindicated, from cycle 2-12. Population pharmacokinetic analysis was performed using nonlinear mixed-effects modeling within the Monolix® software. Fifty SNPs of pharmacokinetic-related genes were genotyped. The influence of demographic, biological, and pharmacogenetic covariates on pharmacokinetic parameters was investigated using a stepwise multivariate procedure. RESULTS: A three-compartment model, with a delayed double zero-order absorption and a first-order elimination, best described VNR pharmacokinetics in children. Typical population estimates for the apparent central volume of distribution (Vc/F) and elimination rate constant were 803 L and 0.60 h-1, respectively. Following covariate analysis, BSA, leukocytes count, and drug transport ABCB1-rs2032582 SNP showed a dramatic impact on Vc/F. Conversely, age and sex had no significant effect on VNR pharmacokinetics. CONCLUSION: Beyond canonical BSA and leukocytes, ABCB1-rs2032582 polymorphism showed a meaningful impact on VNR systemic exposure. Simulations showed that the identified covariates could have an impact on both efficacy and toxicity outcomes. Thus, a personalized dosing strategy, using those covariates, could help to optimize the efficacy/toxicity balance of VNR in children.

Pharmacokinetics of oral vinorelbine in French children with recurrent or progressive primary low-grade glioma.

AIMS: There is a crucial need for pharmacokinetic (PK) data on oral vinorelbine (VNR) in the paediatric population. The aim of this work was to assess the PK profile of orally administered VNR in children with recurrent/progressive primary low-grade glioma (LGG). METHODS: A multicentre, open-label, single-arm intervention phase II study was conducted. Patients, aged between 6 and 18 years, with histologically confirmed recurrent or progressive primary LGG or non-documented typical optic pathway tumours, were included. PK parameters were estimated by non-compartmental analysis using Phoenix WinNonlin® software (version 8.0, Certara, Inc.). The influence of demographic and biological covariates on VNR PK parameters was investigated using a multivariate linear regression analysis. RESULTS: PK analysis included 36 patients with a median age (range) of 11 (6-17) years. Estimates of apparent oral clearance (CL/F), apparent volume of distribution (V/F), half-life (t1/2 ) and their between-subject variability (CV%) at 60 mg m-2 dose level, were 472 L h-1 (51.8%), 7002 L (57.9%) and 10 h (21.0%), respectively. Negligible accumulation of VNR between C1 and C2 was observed. CL/F and V/F were found to increase with body surface area (BSA) (P = .004). Lower area under the concentration-time curve (AUC) levels were observed among children in comparison to adults. CONCLUSION: Higher doses may be necessary for children with LGG. BSA showed a significant impact on VNR systemic exposure. We believe that our findings will serve as a basis for further studies to better characterize the concentration-response relationships of VNR among paediatric patients.

Population pharmacokinetic model of irinotecan and its four main metabolites in patients treated with FOLFIRI or FOLFIRINOX regimen.

PURPOSE: The aim of the present study was to characterize the pharmacokinetics of irinotecan and its four main metabolites (SN-38, SN-38G, APC and NPC) in metastatic colorectal cancer patients treated with FOLFIRI and FOLFIRINOX regimens and to quantify and explain the inter-individual pharmacokinetic variability in this context. METHODS: A multicenter study including 109 metastatic colorectal cancer patients treated with FOLFIRI or FOLFIRINOX regimen, associated or not with a monoclonal antibody, was conducted. Concentrations of irinotecan and its four main metabolites were measured in 506 blood samples during the first cycle of treatment. Collected data were analyzed using the population approach. First, fixed and random effects models were selected using statistical and graphical methods; second, the impact of covariates on pharmacokinetic parameters was evaluated to explain the inter-individual variability in pharmacokinetic parameters. RESULTS: A seven-compartment model best described the pharmacokinetics of irinotecan and its four main metabolites. First-order rates were assigned to distribution, elimination, and metabolism processes, except for the transformation of irinotecan to NPC which was nonlinear. Addition of a direct conversion of NPC into SN-38 significantly improved the model. Co-administration of oxaliplatin significantly modified the distribution of SN-38. CONCLUSION: To our knowledge, the present model is the first to allow a simultaneous description of irinotecan pharmacokinetics and of its four main metabolites. Moreover, a direct conversion of NPC into SN-38 had never been described before in a population pharmacokinetic model of irinotecan. The model will be useful to develop pharmacokinetic-pharmacodynamic models relating SN-38 concentrations to efficacy and digestive toxicities. CLINICAL TRIALS REGISTRATION NUMBER: ClinicalTrials.gov identifier: NCT00559676.

Prior information for population pharmacokinetic and pharmacokinetic/pharmacodynamic analysis: overview and guidance with a focus on the NONMEM PRIOR subroutine.

Population pharmacokinetic analysis is used to estimate pharmacokinetic parameters and their variability from concentration data. Due to data sparseness issues, available datasets often do not allow the estimation of all parameters of the suitable model. The PRIOR subroutine in NONMEM supports the estimation of some or all parameters with values from previous models, as an alternative to fixing them or adding data to the dataset. From a literature review, the best practices were compiled to provide a practical guidance for the use of the PRIOR subroutine in NONMEM. Thirty-three articles reported the use of the PRIOR subroutine in NONMEM, mostly in special populations. This approach allowed fast, stable and satisfying modelling. The guidance provides general advice on how to select the most appropriate reference model when there are several previous models available, and to implement and weight the selected parameter values in the PRIOR function. On the model built with PRIOR, the similarity of estimates with the ones of the reference model and the sensitivity of the model to the PRIOR values should be checked. Covariates could be implemented a priori (from the reference model) or a posteriori, only on parameters estimated without prior (search for new covariates).

Usefulness of therapeutic drug monitoring of rilpivirine and its relationship with virologic response and resistance in a cohort of naive and pretreated HIV-infected patients.

AIMS: The purpose of this study was to assess the antiviral activity of the rilpivirine/emtricitabine/tenofovir disoproxil fumarate combination and to describe the pharmacokinetics of rilpivirine and its association with resistance in clinical routine. METHODS: A retrospective multicentre cohort study was performed in both naive and pretreated HIV patients receiving the once-daily rilpivirine/emtricitabine/tenofovir disoproxil fumarate regimen. Immuno-virologic and resistance data, and rilpivirine plasma trough concentrations were collected over the follow-up. Statistical analyses were performed to evaluate the relationship between rilpivirine pharmacokinetics and virological response. Receiver operating characteristic (ROC) curve analysis was performed to determine the best target rilpivirine trough concentration. RESULTS: Overall, 379 patients were included. After a median follow-up of 28 months, 26% of patients discontinued mainly due to toxicity and the virological success rate was 65.7%. Virological failure occurred in 5% of patients. A significant proportion of patients with HIV-RNA > 40 copies/mL displayed rilpivirine plasma trough concentrations below the currently used 50 ng/mL efficacy threshold at both M6 (28%) and M12 (31%), in agreement with a significant lower median rilpivirine plasma trough concentration compared with patients virologically suppressed. Half of the patients with virologic failure who acquired rilpivirine resistance mutations had at least one suboptimal rilpivirine trough concentration. The optimal target for rilpivirine trough concentration was 70 ng/mL (sensitivity 75.4%; specificity 61.5%). CONCLUSIONS: This study shows the impact of rilpivirine plasma trough concentration on both virological response and the emergence of rilpivirine mutations. Moreover, our results suggest that a higher target of rilpivirine trough concentration could be proposed in clinical practice.

Pharmacogenetics and pharmacokinetics modeling of unexpected and extremely severe toxicities after sorafenib intake.

A 53-year-old woman with papillary thyroid cancer treated with 800 mg sorafenib therapy rapidly experienced grade 3 toxicities. Dosing was reduced in a step-wise manner with several treatment discontinuations down to 200 mg every 2 days but severe toxicities continued. Plasma drug monitoring showed high exposure, even at low dose. Dosing was then further reduced at 200 mg every 3 days and tolerance was finally acceptable (i.e., grade 1 toxicity) with stable disease upon RECIST imaging. Pharmacogenetic investigations showed polymorphisms affecting both UGT1A9 (UGT1A9-rs3832043) and nuclear receptor PXR (NR1I2-rs3814055, NR1I2-rs2472677 and NR1I2-rs10934498), possibly resulting in downregulation of liver metabolizing enzymes of sorafenib (i.e., CYP and UGT). Patient's clearance (0.48 l/h) estimated by Bayesian approach was consistently lower than usually described. This is the first time that, in addition to mutations affecting UGT1A9, genetic polymorphisms of NR1I2 have possibly been associated with both plasma overexposure and severe toxicities upon sorafenib intake.

Enhanced anti-angiogenic effects of bevacizumab in glioblastoma treatment upon intranasal administration in polymeric nanoparticles.

Glioblastoma multiforme (GBM) is one of the most aggressive cancers, where the aggressiveness of tumor has been associated to its high vascularization rate. Bevacizumab (Avastin®), an anti-angiogenic monoclonal antibody, has been used to decrease the angiogenic profile. To circumvent the blood-brain barrier (BBB) and decrease off-target organ toxicity, bevacizumab-loaded poly(D,L-lactic-co-glycolic acid) nanoparticles (PLGA NP) were developed and intranasally administrated in CD-1 mice to study their pharmacokinetic and pharmacodynamic profile. After 7 days of administration, PLGA NP showed a higher brain bioavailability of bevacizumab when compared to intranasally administrated free bevacizumab. On the other hand, bevacizumab-loaded PLGA NP were able to increase the penetration (higher Cmáx) and the residence time of bevacizumab into the brain (higher Clast). Furthermore, PLGA NP formulation totally prevented bevacizumab systemic exposure. The efficacy of this nanosystem was next evaluated in a validated orthotopic GBM nude mice model, studying the tumor growth over time by bioluminescence and the anti-angiogenic effects. After 14 days, bevacizumab-loaded PLGA NP demonstrated a reduction in the tumor growth accompanied by a higher anti-angiogenic effect compared to the free bevacizumab. These results can be explained by the fact that bevacizumab was found in the brain just for bevacizumab-loaded PLGA NP group, after 14 days of formulation administration. Therefore, we believe that our strategy would be an efficient alternative to improve GBM treatment with high impact for patient life quality and survival.

Concentration-response model of rilpivirine in a cohort of HIV-1-infected naive and pre-treated patients.

BACKGROUND: Rilpivirine is widely prescribed in people living with HIV. Although trough plasma concentrations have been associated with virological response, the drug pharmacodynamics remain incompletely characterized. OBJECTIVES: To develop the first pharmacodynamic model of rilpivirine in order to establish the rilpivirine concentration-response relationship for future treatment optimization. METHODS: A retrospective observational study was conducted in patients receiving the once-daily rilpivirine/tenofovir disoproxil fumarate/emtricitabine regimen. Individual rilpivirine trough plasma concentrations over time were predicted using a previous pharmacokinetic model. An established susceptible, infected, recovered model was used to describe HIV dynamics without assuming disease steady-state. Population analysis was performed with MONOLIX 2018 software. Simulations of the viral load evolution as a function of time and rilpivirine trough plasma concentration were performed. RESULTS: Overall, 60 naive and 39 pre-treated patients were included with a follow-up ranging from 2 to 37 months. The final model adequately described the data and the pharmacodynamic parameters were estimated with a good precision. The population typical value of rilpivirine EC50 was estimated at 65 ng/mL. A higher infection rate constant of CD4 cells for HIV-1 was obtained in pre-treated patients. Consequently, the time to obtain virological suppression was longer in pre-treated than in naive patients. CONCLUSIONS: The concentration-response relationship of rilpivirine was satisfactorily described for the first time using an original population pharmacodynamic model. Simulations performed using the final model showed that the currently used 50 ng/mL rilpivirine trough plasma concentration efficacy target might need revision upwards, particularly in pre-treated patients.

Population pharmacokinetics of FOLFIRINOX: a review of studies and parameters.

PURPOSE: FOLFIRINOX regimen is commonly used in colorectal and more recently pancreatic cancer. However, FOLFIRINOX induces significant and dose-limiting toxic effects leading to empirical dose reduction and sometimes treatment discontinuation. Model-based FOLFIRINOX regimen optimization might help improving patients' outcome. As a first step, the current review aims at bringing together all published population pharmacokinetics models for FOLFIRINOX anticancer drugs. METHODS: A literature search was conducted in the PubMed database from inception to February 2018, using the following terms: population pharmacokinetic(s), irinotecan, oxaliplatin, fluorouracil, FOLFIRI, FOLFOX, FOLFIRINOX. Only articles displaying nonlinear mixed effect models were included. Study description, pharmacokinetic parameter values and influential covariates are reported. For each model, the typical pharmacokinetic profile was simulated for the standard FOLFIRINOX protocol. RESULTS: The FOLFIRINOX compounds have been studied only separately so far. A total of six articles were retained for 5-fluorouracil, 6 for oxaliplatin and 5 for irinotecan (also including metabolites). Either one- or two-compartment models have been described for 5-fluorouracil, while two- or three-compartment models were reported for oxaliplatin and irinotecan pharmacokinetics. Non-linear elimination was sometimes reported for 5-fluorouracil. Sex and body size were found as influential covariates for all molecules in some publications. Despite some differences in model structures and parameter values, the simulated profiles and subsequent exposure were consistent between studies. CONCLUSIONS: The current review allows for a global understanding of FOLFIRINOX pharmacokinetics, and will provide a basis for further development of pharmacokinetics-pharmacodynamics-toxicity models for model-driven FOLFIRINOX protocol optimization to reach the best benefit-to-risk ratio.

Population pharmacokinetics of Rilpivirine in HIV-1-infected patients treated with the single-tablet regimen rilpivirine/tenofovir/emtricitabine.

PURPOSE: Rilpivirine, prescribed for the treatment of HIV infection, presents an important inter-individual pharmacokinetic variability. We aimed to determine population pharmacokinetic parameters of rilpivirine in adult HIV-infected patients and quantify their inter-individual variability. METHODS: We conducted a multicenter, retrospective, and observational study in patients treated with the once-daily rilpivirine/tenofovir disoproxil fumarate/emtricitabine regimen. As part of routine therapeutic drug monitoring, rilpivirine concentrations were measured by UPLC-MS/MS. Population pharmacokinetic analysis was performed using NONMEM software. Once the compartmental and random effects models were selected, covariates were tested to explain the inter-individual variability in pharmacokinetic parameters. The final model qualification was performed by both statistical and graphical methods. RESULTS: We included 379 patients, resulting in the analysis of 779 rilpivirine plasma concentrations. Of the observed trough individual plasma concentrations, 24.4% were below the 50 ng/ml minimal effective concentration. A one-compartment model with first-order absorption best described the data. The estimated fixed effect for plasma apparent clearance and distribution volume were 9 L/h and 321 L, respectively, resulting in a half-life of 25.2 h. The common inter-individual variability for both parameters was 34.1% at both the first and the second occasions. The inter-individual variability of clearance was 30.3%. CONCLUSIONS: Our results showed a terminal half-life lower than reported and a high proportion of patients with suboptimal rilpivirine concentrations, which highlights the interest of using therapeutic drug monitoring in clinical practice. The population analysis performed with data from "real-life" conditions resulted in reliable post hoc estimates of pharmacokinetic parameters, suitable for individualization of dosing regimen.

Imidazoquinoxaline anticancer derivatives and imiquimod interact with tubulin: Characterization of molecular microtubule inhibiting mechanisms in correlation with cytotoxicity.

Displaying a strong antiproliferative activity on a wide variety of cancer cells, EAPB0203 and EAPB0503 belong to the imidazo[1,2-a]quinoxalines family of imiquimod structural analogues. EAPB0503 has been shown to inhibit tubulin polymerization. The aim of the present study is to characterize the interaction of EAPB0203 and EAPB0503 with tubulin. We combine experimental approaches at the cellular and the molecular level both in vitro and in silico in order to evaluate the interaction of EAPB0203 and EAPB0503 with tubulin. We examine the influence of EAPB0203 and EAPB0503 on the cell cycle and fate, explore the binding interaction with purified tubulin, and use a computational molecular docking model to determine the binding modes to the microtubule. We then use a drug combination study with other anti-microtubule agents to compare the binding site of EAPB0203 and EAPB0503 to known potent tubulin inhibitors. We demonstrate that EAPB0203 and EAPB0503 are capable of blocking human melanoma cells in G2 and M phases and inducing cell death and apoptosis. Second, we show that EAPB0203 and EAPB0503, but also unexpectedly imiquimod, bind directly to purified tubulin and inhibit tubulin polymerization. As suggested by molecular docking and binding competition studies, we identify the colchicine binding site on ß-tubulin as the interaction pocket. Furthermore, we find that EAPB0203, EAPB0503 and imiquimod display antagonistic cytotoxic effect when combined with colchicine, and disrupt tubulin network in human melanoma cells. We conclude that EAPB0203, EAPB0503, as well as imiquimod, interact with tubulin through the colchicine binding site, and that the cytotoxic activity of EAPB0203, EAPB0503 and imiquimod is correlated to their tubulin inhibiting effect. These compounds appear as interesting anticancer drug candidates as suggested by their activity and mechanism of action, and deserve further investigation for their use in the clinic.

Population Pharmacokinetics of Gemcitabine and dFdU in Pancreatic Cancer Patients Using an Optimal Design, Sparse Sampling Approach.

BACKGROUND: Gemcitabine remains a pillar in pancreatic cancer treatment. However, toxicities are frequently observed. Dose adjustment based on therapeutic drug monitoring might help decrease the occurrence of toxicities. In this context, this work aims at describing the pharmacokinetics (PK) of gemcitabine and its metabolite dFdU in pancreatic cancer patients and at identifying the main sources of their PK variability using a population PK approach, despite a sparse sampled-population and heterogeneous administration and sampling protocols. METHODS: Data from 38 patients were included in the analysis. The 3 optimal sampling times were determined using KineticPro and the population PK analysis was performed on Monolix. Available patient characteristics, including cytidine deaminase (CDA) status, were tested as covariates. Correlation between PK parameters and occurrence of severe hematological toxicities was also investigated. RESULTS: A two-compartment model best fitted the gemcitabine and dFdU PK data (volume of distribution and clearance for gemcitabine: V1 = 45 L and CL1 = 4.03 L/min; for dFdU: V2 = 36 L and CL2 = 0.226 L/min). Renal function was found to influence gemcitabine clearance, and body surface area to impact the volume of distribution of dFdU. However, neither CDA status nor the occurrence of toxicities was correlated to PK parameters. CONCLUSIONS: Despite sparse sampling and heterogeneous administration and sampling protocols, population and individual PK parameters of gemcitabine and dFdU were successfully estimated using Monolix population PK software. The estimated parameters were consistent with previously published results. Surprisingly, CDA activity did not influence gemcitabine PK, which was explained by the absence of CDA-deficient patients enrolled in the study. This work suggests that even sparse data are valuable to estimate population and individual PK parameters in patients, which will be usable to individualize the dose for an optimized benefit to risk ratio.

Biodistribution and pharmacokinetics of Mad2 siRNA-loaded EGFR-targeted chitosan nanoparticles in cisplatin sensitive and resistant lung cancer models.

BACKGROUND: The present study focuses on biodistribution profile and pharmacokinetic parameters of EGFR-targeted chitosan nanoparticles (TG CS nanoparticles) for siRNA/cisplatin combination therapy of lung cancer. MATERIAL & METHODS: Mad2 siRNA was encapsulated in EGFR targeted and nontargeted (NTG) CS nanoparticles by electrostatic interaction. The biodistribution of the nanoparticles was assessed qualitatively and quantitatively in cisplatin (DDP) sensitive and resistant lung cancer xenograft model. RESULTS: TG nanoparticles showed a consistent and preferential tumor targeting ability with rapid clearance from the plasma to infiltrate and sustain within the tumor up to 96 h. They exhibit a sixfold higher tumor targeting efficiency compared with the NTG nanoparticles. CONCLUSION: TG nanoparticles present as an attractive drug delivery platform for RNAi therapeutics against NSCLC.

Comparative Biodistribution and Pharmacokinetic Analysis of Cyclosporine-A in the Brain upon Intranasal or Intravenous Administration in an Oil-in-Water Nanoemulsion Formulation.

The main objective of this study was to evaluate comparative biodistribution and pharmacokinetics of cyclosporine-A (CsA) following intranasal (IN) administration versus intravenous (IV) administration in Sprague-Dawley rats using an oil-in-water nanoemulsion delivery system. CsA, a hydrophobic peptide that is also a substrate for P-glycoprotein, is a well-known immunosuppressive agent. In the brain, CsA has been shown to be a potent anti-inflammatory and neuroprotective agent. CsA nanoemulsions (CsA-NE) and solution formulations (CsA-S) were prepared using an ultrasonication method and were characterized for drug content, encapsulation efficiency, globule size, and zeta potential. We compared the uptake of CsA-NE and CsA-S in brain regions and peripheral organs following IN and IV administration using LC-MS/MS based bioanalytical method. CsA-NE IN resulted in the highest accumulation compared to that with any other treatment and route of administration; this was consistent for all three regions of brain that were evaluated (olfactory bulbs, mid brain, and hind brain). The brain/blood exposure ratios of 4.49, 0.01, 0.33, and 0.03 for CsA-NE (IN), CsA-NE (IV), CsA-S (IN), and CsA-S (IV), respectively, indicated that CsA-NE is capable of direct nose-to-brain transport, bypassing the blood-brain barrier. Furthermore, CsA-NE administration reduces nontarget organ exposure. These studies show that IN delivery of CsA-NE is an effective way of brain targeting compared to that of other treatment strategies. This approach not only enhances the brain concentration of the peptide but also significantly limits peripheral exposure and the potential for off-target toxicity.

Comparative pharmacokinetics and tissue distribution analysis of systemically administered 17-ß-estradiol and its metabolites in vivo delivered using a cationic nanoemulsion or a peptide-modified nanoemulsion system for targeting atherosclerosis.

The primary objective of this study was to compare the biodistribution and pharmacokinetic profile of 17-ß-estradiol (17-ßE) on systemic delivery using either the cationic or the CREKA-peptide-modified (Cysteine-Arginine-Glutamic-acid-Lysine-Alanine) omega-3-fatty acid oil containing nanoemulsion system in vivo in the wild type C57BL/6 mice. Higher blood concentrations of 17-ßE, higher accumulation in the tissues of interest - heart and aorta, and higher accumulation within the other tissues - liver and kidney was observed on delivering 17-ßE using the CREKA-peptide-modified nanoemulsion system (AUClast in plasma - 263.89±21.81min*%/injected dose/ml) as compared to the cationic nanoemulsion (AUClast in plasma - 20.2±1.86min*%/injected dose/ml) and solution form (AUClast in plasma - 44.9±1.24min*%/injected dose/ml) respectively. Both, the cationic nanoemulsion and the CREKA-peptide-modified nanoemulsion showed a higher relative targeting efficiency of 4.57 and 4.86 respectively for 17-ßE than the relative targeting efficiency of 1.78 observed with the solution form. In conclusion, since the maximum exposure (highest AUClast for plasma and tissues) for 17-ßE was observed with the CREKA-peptide-modified nanoemulsion system, the study shows that CREKA-peptide-modified nanoemulsion system was the most suitable vehicle for systemic delivery of 17-ßE in the wild type C57BL/6 mice.

CNS delivery and pharmacokinetic evaluations of DALDA analgesic peptide analog administered in Nano-sized oil-in-water emulsion formulation.

PURPOSE: Although neuro-active peptides are highly potent as central nervous system (CNS) therapeutics, their systemic delivery across the blood-brain barrier (BBB) is limited due to lack of permeability in the brain and rapid systemic metabolism. In this study, we aimed at enhancing the brain delivery and stability of chemically modified [D-Arg(2), Lys(4)]-dermorphin-(1-4)-amide)] (DALDA) peptide to achieve prolonged analgesic effects. METHODS: The C8-DALDA peptide analog was encapsulated in an oil-in-water nanoemulsion formulation made specifically with oils rich in omega-3 rich polyunsaturated fatty acid (PUFA) to enhance CNS availability. The nanoemulsion formulation was administered systemically in CD-1 mice and qualitative and quantitative biodistribution was evaluated. We have also examined the effect of curcumin, which is known to down-regulate efflux transporters and inhibit systemic metabolism, on the pharmacokinetic properties of the peptide. RESULTS: Qualitative and quantitative biodistribution and pharmacokinetic studies in mice clearly demonstrated improved plasma and brain exposure of modified DALDA when administered in nanoemulsion, thereby providing an exciting opportunity towards improved efficacy and/or lowered dose of the peptide. The various dosing regimens tested for modified DALDA solution and curcumin nanoemulsion directed towards a novel combination strategy for improved systemic delivery of peptides across the BBB. CONCLUSIONS: Encapsulation of the drug in PUFA nanoemulsion is an effective strategy for delivery of peptides. This work provides a novel combination strategy for improved delivery of peptides to the brain.

In vivo biodistribution of siRNA and cisplatin administered using CD44-targeted hyaluronic acid nanoparticles.

Multidrug resistance (MDR) is a significant problem in the clinical management of several cancers. Overcoming MDR generally involves multi-modal therapeutic approaches that integrate enhancement of delivery efficiency using targeted nano-platforms as well as strategies that can sensitize cancer cells to drug treatments. We recently demonstrated that tandem delivery of siRNAs that downregulate anti-apoptotic genes overexpressed in cisplatin resistant tumors followed by therapeutic challenge using cisplatin loaded CD44 targeted hyaluronic acid (HA) nanoparticle (NP) induced synergistic antitumor response CD44 expressing tumors that are resistant to cisplatin. In the current study, a near infrared (NIR) dye-loaded HA NP was employed to image the whole body localization of NPs after intravenous (i.v.) injection into live mice bearing human lung tumors that were sensitive and resistant to cisplatin. In addition, we quantified the siRNA duplexes and cisplatin dose distribution in various tissues and organs using an ultra-sensitive quantitative PCR method and inductively coupled plasma-mass spectrometry (ICP-MS), respectively, after i.v. injection of the payload loaded HA NPs in tumor bearing mice. Our findings demonstrate that the distribution pattern of the siRNA and cisplatin using specifically engineered CD44 targeting HA NPs correlated well with the tumor targeting capability as well as the activity and efficacy obtained with combination treatments.

Additional cytotoxic pyridoacridine alkaloids from the ascidian Cystodytes violatinctus and biogenetic considerations.

The extraction and purification of the bioactive extract of Cystodytes violatinctus (Solomon Islands) led to the isolation and identification of six pyridoacridine alkaloids. The structures of four new members of this family, shermilamine F (1), dehydrokuanoniamine F (2), and arnoamines C (3) and D (4), were elucidated on the basis of NMR and MS data and by comparison with data of known compounds isolated from this genus. A general hypothetical biogenetic pathway is then proposed for pyridoacridine alkaloids that contain a fused pyrrole ring. Comparison of the biological properties of the isolated alkaloids is also discussed.