Plasma Half-life Research Articles

Divergent Modulation of Activated Protein C Pleiotropic Functions by Antibodies That Differ by A Single Amino Acid.

Activated protein C (APC) is a pleiotropic plasma protease with diverse functions derived from its anticoagulant, anti-inflammatory, and cytoprotective activities. The selective uncoupling and/or modulation of these APC activities by antibodies may have therapeutic benefit in diseases such as traumatic bleeding, hemophilia, sepsis, and ischemia. TPP-26870 is an antibody that targets a non-active site of APC for the selective modulation of APC activities. To optimize the potency of TPP-26870, variants with single amino acid mutation in the complementarity-determining regions (CDRs) were screened, and 21 variants with improved KD were identified. Interestingly, the affinity maturation of TPP-26870 did not merely generate a panel of variants with higher potency in functional assays. Functional data demonstrated that the pleiotropic functions of APC were very sensitive to epitope-CDR interactions. Single amino acid mutations within the CDRs of TPP-26870 were sufficient to elicit divergent antagonistic and agonistic effects on the various APC functional activities. These include prolonged in vitro APC plasma half-life, increased inhibition of anticoagulant activity, and agonistic enhancement of histone H3 cleavage, while having less impact on PAR1 cleavage in comparison to TPP-26870. This study illustrates that APC is highly sensitive to non-active site targeting that can lead to unpredictable changes in its activity profile of this pleiotropic enzyme. Further, this study demonstrates the ability to modify APC functions to advance the potential development of APC targeted antibodies as therapeutics for the treatment of diseases including trauma bleeding, hemophilia, ischemia, and sepsis.

First-in-human study to evaluate the safety, pharmacokinetics (PK), and pharmacodynamics (PD) of RBD4059, a GalNAc-siRNA drug targeting coagulation factor XI (FXI), in healthy subjects

Abstract Background Patients at risk of thrombosis/thromboembolism, require effective and safe anti-coagulation with high compliance. Inhibiting FXI has emerged as a promising strategy with potential for lower bleeding risk compared to currently approved anti-coagulants. Here we report on the safety, PK and PD effects of the GalNAc-conjugated siRNA RBD4059, specifically targeting and repressing FXI protein synthesis in the liver. Purpose Investigate safety, PK, and PD of first-in-human dosing of RBD4059 in healthy subjects. Methods A randomized, single-blind, placebo-controlled, single ascending dose (SAD) phase I study in healthy subjects (NCT05653037), in cohorts of eight randomized 3:1 to receive escalating doses of RBD4059 (50, 150, and 400 mg) or placebo administered subcutaneously. Results As of January 25, 2024, 24 subjects (with follow-up to week 24) with demographics and baseline clinical characteristics shown in Table 1 were enrolled. RBD4059 was well tolerated (Table 2), all related AEs were grade 1. There was no evidence of any clinically relevant bleeding events. Plasma exposure of RBD4059 tended to increase in proportion to the dose. Maximum concentration in plasma (Cmax) was reached in 2 to 4 h and then declined in line with one-compartment kinetics. The mean plasma half-life (t1/2) ranged from 3.2 to 7.0 h. RBD4059 treatment resulted in dose dependent and sustained reductions in FXI activity and FXI antigen (Figure 1A, B, D). Observed mean maximum percentage change from baseline in FXI activity from the 50 mg, 150 mg, and 400 mg SAD cohorts were 67.5%, 81.0%, and 85.8%, respectively, recovering with a maintained effect observed on D141 (50mg: 50.6% inhibition; 150mg: 68.2% inhibition). The reduction in FXI antigen showed a very similar pattern as the reduction in FXI activity, and reductions were accompanied by a concomitant increase in APTT. (Figure 1C, D). PKPD modelling supports that RBD4059 may be dosed every 3 months or less frequent with a >90% FXI reduction throughout the dosing interval, and will be tested in the upcoming phase 2 study. Conclusion(s) RBD4059 demonstrated favorable safety, predictable PK, and pronounced durable PD effect in the dose range of 50 mg - 400 mg. This first-in-human SAD study supports the further development of RBD4059 as an anticoagulant that can maintain a high level of PD effect with a once every 3 month or less frequent dosing regimen, with potential for enhanced compliance in chronic anti-coagulant therapy.Table 1 & Table 2Figure 1.Panels A-D

Synthesis of a dehydrodieugenol B derivative as a lead compound for visceral leishmaniasis-mechanism of action and in vivo pharmacokinetic studies.

Leishmaniasis is a parasitic neglected tropical disease, affecting 12 million people. Available treatments present several limitations, with an increasing number of resistance cases. In the search for new chemotherapies, the natural product dehydrodieugenol B was used as a scaffold for the synthesis of a series of derivatives, resulting in the discovery of the promising analog [4-(4-(5-allyl-3-methoxy-2-((4-methoxybenzyl)oxy)phenoxy)-3-methoxybenzyl)morpholine, 1]. In this work, we investigated the effect of compound 1 on cell signaling in Leishmania (L.) infantum, culminating in cell death, as well as its immunomodulatory effect in the host cell. Additionally, we performed a pharmacokinetic profile study in an animal model. After treatment, compound 1 induced the alkalinization of acidocalcisomes and concomitant Ca2+ release in the parasite. These events may induce depolarization of the mitochondrial potential, with successive collapse of the bioenergetic system, leading to a reduction of ATP and reactive oxygen species (ROS) levels. The analysis of total proteins and protein profile by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF/MS) demonstrated that compound 1 also altered the parasite proteins after treatment. Transmission electron microscopy studies revealed ultrastructural damage to mitochondria; together, these data suggest that compound 1 may promote autophagic cell death. Additionally, compound 1 also induced an immunomodulatory effect in host cells, with a reduction of Th1 and Th2 cytokine response, characterizing an anti-inflammatory compound. The obtained pharmacokinetic profile in rats enhances the potential of the compound, with a mean plasma half-life (T1/2) of 21 h. These data reinforce the potential of compound 1 as a new lead for future efficacy studies.

A phase III, open-label clinical trial evaluating pegunigalsidase alfa administered every 4 weeks in adults with Fabry disease previously treated with other enzyme replacement therapies.

Pegunigalsidase alfa, a PEGylated α-galactosidase A enzyme replacement therapy (ERT) for Fabry disease, has a longer plasma half-life than other ERTs administered intravenously every 2 weeks (E2W). BRIGHT (NCT03180840) was a phase III, open-label study in adults with Fabry disease, previously treated with agalsidase alfa or beta E2W for ≥3 years, who switched to 2 mg/kg pegunigalsidase alfa every 4 weeks (E4W) for 52 weeks. Primary objective assessed safety, including number of treatment-emergent adverse events (TEAEs). Thirty patients were enrolled (24 males); 23 previously received agalsidase beta. Pegunigalsidase alfa plasma concentrations remained above the lower limit of quantification throughout the 4-week dosing interval. Thirty-three of 182 TEAEs (in 9 patients) were considered treatment-related; all were mild/moderate. No patients developed de novo anti-drug antibodies (ADAs). In the efficacy analysis (n = 29), median (inter-quartile range) eGFR change from baseline over 52 weeks was -1.9 (-5.9; 1.8) mL/min/1.73 m2 (n = 28; males [n = 22]: -2.4 [-5.2; 3.2]; females [n = 6]: -0.7 [-9.2; 2.0]). Overall, median eGFR slope was -1.9 (-8.3; 1.9) mL/min/1.73 m2/year (ADA-negative [n = 20]: -1.2 [-6.4; 2.6]; ADA-positive [n = 9]: -8.4 [-11.6; -1.0]). Lyso-Gb3 concentrations were low and stable in females, with a slight increase in males (9/24 ADA-positive). The BRIGHT study results suggest that 2 mg/kg pegunigalsidase alfa E4W is tolerated well in stable adult patients with Fabry disease. Due to the low number of patients in this study, more research is needed to demonstrate the effects of pegunigalsidase alfa given E4W. Further evidence, outside of this clinical trial, should be factored in for physicians to prolong the biweekly ERT intervals to E4W. TAKE-HOME MESSAGE: Treatment with 2 mg/kg pegunigalsidase alfa every 4 weeks could offer a new treatment option for patients with Fabry disease.

Medication Dosing for Children With Overweight and Obesity.

Approximately 14.7 million US children aged 2 to 19 years are obese. This creates significant challenges to dosing medications that are primarily weight based (mg/kg) and in predicting pharmacokinetics parameters in pediatric patients. Obese individuals generally have a larger volume of distribution (Vd) for lipophilic medications. Conversely, the Vd of hydrophilic medications may be increased or decreased owing to increased lean body mass, blood volume, and decreased percentage of total body water. They may also experience decreased hepatic clearance secondary to fatty infiltrates of the liver. Hence, obesity may affect loading dose, dosage interval, plasma half-life, and time to reach steady-state concentration for various medications. Weight-based dosing is also a cause for potential medication errors. This position statement of the Pediatric Pharmacy Association recommends that weight-based dosing should be used in patients ages <18 years who weigh <40 kg; weight-based dosing should be used in patients ≥40 kg, unless the recommended adult dose for the specific indication is exceeded; clinicians should use pharmacokinetic analysis for adjusting medications in children diagnosed with overweight and obesity; and research efforts continue to evaluate dosing of medications in children diagnosed with overweight and obesity.

Rhamnosomes: A new generation of flexible vesicles for a boosted targeted nose-to-brain delivery of selegiline in the treatment of Parkinson's disease

Extensive hepatic metabolism of Selegiline, a selective monoamine oxidase B inhibitor for newly diagnosed Parkinson's disease patients, causes limited brain bioavailability. To improve efficacy, a new generation of flexible lipidic vesicles, Rhamnosomes, comprising alternating lecithin and Rhamnolipid moieties, and decorated with lactoferrin to actively target Selegiline to the brain is proposed.Rhamnosomes were optimized using design of expert, where lipid amount, Soybean lecithin:Rhamnolipid ratio and sonication time were varied. Polyelectrolyte complexation was employed for Lactoferrin conjugation to Rhamnosomes. A pharmacokinetic study in rat plasma and brain was conducted. Optimized Rhamnosomes had a particle size of 107nm, polydispersity index of 0.23, zeta potential of -41mV, entrapment efficiency of 78%, relative deformability of 36sec and ex-vivo skin permeation reaching 60% after 24 hr. The plasma half life of Rhamnosomes was 3.24 times the market product and 2.63 times the intravenous solution, whereas, lactoferrin-conjugated Rhamnosomes exhibited 7 times higher absolute bioavailability than the market product and more than double its brain drug targeting efficiency. Prominent direct nose-to-brain transport values further proved the efficiency of intranasally delivered Selegiline-loaded Lactoferrin conjugated Rhamnosomes to actively target the brain in a non-invasive approach for the treatment of Parkinson's disease.

Multifunctional Dendrimer-Peptide Conjugates for MET Receptor-specific Imaging of Cancer Cells

The Mesenchymal Epithelial Transition (MET) receptor tyrosine kinase is frequently upregulated or mutated in various cancers. Targeting MET signaling pathway has been utilized as a treatment for cancer, as since MET overexpression is often associated with poor prognosis. Selective imaging of MET-overexpressing tumor cells would thus provide a high diagnostic value; however, it remains elusive due to a lack of targeted imaging contrast agents. Herein, we have developed a multifunctional diagnostic dendrimer-peptide conjugate (DPC) system with a strong avidity to MET-expressing cancer cells. The system was prepared by conjugating MET-inhibiting peptides (C7) to generation 7 (G7) poly(amidoamine) (PAMAM) dendrimers. Due to the dendrimer-mediated multivalent binding effect, the DPCs exhibited a significantly stronger binding to the human MET protein than free C7, as measured using surface plasmon resonance. Confocal microscopy revealed increased binding of the DPCs to the MET-expressing EBC-1 and UW-Lung-21 cells, whereas a MET knock-out cell line showed negligible interactions with the DPCs. The DPCs were then conjugated with Zirconium-89 for positron emission tomography and computed tomography (PET/CT) scanning, demonstrating their selective accumulation to MET-expressing tumors in vivo. Additionally, the plasma half-life of the DPCs was measured at ~53hours, which was significantly longer than free C7. These results collectively suggest that this DPC system has potential as a targeted imaging platform specific to MET-expressing tumors, which would be applicable to various cancer types.

Subacute Toxicity and Pharmacokinetic Evaluation of the Synthetic Cannabinoid 4F-MDMB-BUTINACA in Rats: A Forensic and Toxicological Perspective

Background: 4-MDMB-BUTINACA, a next-generation synthetic cannabinoid, presents significant public health and forensic challenges due to its evolving nature and potential toxicity. Methods: This study evaluates the subacute toxic effects and pharmacokinetics of 4−Fluoro MDMB−BUTINACA (4F-MDMB-BUTINACA) in adult male albino rats, administered orally for seven days at doses of 1 mg/kg, 5 mg/kg, and 15 mg/kg. The hematological, biochemical, and histopathological parameters were assessed and compared to controls. Results: The pharmacokinetics were determined using GC–MS/MS with a positive chemical ionization and granisetron as an internal standard. A histological analysis revealed inflammatory cell aggregation, congestion, hemorrhage, edema, and fibrosis in various tissues, with renal examinations showing tubule degradation, glomerular atrophy, Bowman’s space expansion, edema, and hemorrhage. The liver exhibited cellular infiltration, while cardiac muscle fibers showed myocardial fiber degradation and inflammatory cell aggregation. Biochemical assays indicated significant alterations (p &lt; 0.05) in the serum levels of AST, ALT, ALP, GGT, total protein, albumin, triglycerides, urea, MCHC, MCV, RDW, platelets, neutrophils, eosinophils, and basophils compared to the controls. Conclusions: The validated bioanalytical method revealed rapid absorption of 4F-MDMB-BUTINACA, with a plasma half-life of 2.371 h, a volume of distribution of 2272.85 L, and a plasma clearance rate of 664.241 L/h. In conclusion, 4F-MDMB-BUTINACA is a highly toxic synthetic cannabinoid, particularly affecting the liver, kidneys, and heart.

Development of machine learning-based quantitative structure–activity relationship models for predicting plasma half-lives of drugs in six common food animal species

Abstract Plasma half-life is a crucial pharmacokinetic parameter for estimating extralabel withdrawal intervals of drugs to ensure the safety of food products derived from animals. This study focuses on developing a quantitative structure–activity relationship (QSAR) model incorporating multiple machine learning and artificial intelligence algorithms, and aims to predict the plasma half-lives of drugs in 6 food animals, including cattle, chickens, goats, sheep, swine, and turkeys. By integrating 4 machine learning algorithms with 5 molecular descriptor types, 20 QSAR models were developed using data from the Food Animal Residue Avoidance Databank (FARAD) Comparative Pharmacokinetic Database. The deep neural network (DNN) algorithm demonstrated the best prediction ability of plasma half-lives. The DNN model with all descriptors achieved superior performance with a high coefficient of determination (R2) of 0.82 ± 0.19 in 5-fold cross-validation on the training sets and an R2 of 0.67 on the independent test set, indicating accurate predictions and good generalizability. The final model was converted to a user-friendly web dashboard to facilitate its wide application by the scientific community. This machine learning-based QSAR model serves as a valuable tool for predicting drug plasma half-lives and extralabel withdrawal intervals in 6 common food animals based on physicochemical properties. It also provides a foundation to develop more advanced models to predict the tissue half-life of drugs in food animals.

Improving Circulation Half-Life of Therapeutic Candidate N-TIMP2 by Unfolded Peptide Extension.

Matrix metalloproteinases (MMPs) are significant drivers of many diseases, including cancer, and are established targets for drug development. Tissue inhibitors of metalloproteinases (TIMPs) are endogenous MMP inhibitors and are being pursued for the development of anti-MMP therapeutics. TIMPs possess many attractive properties for drug candidates, such as complete MMP inhibition, low toxicity, low immunogenicity, and high tissue permeability. However, a major challenge with TIMPs is their rapid clearance from the bloodstream due to their small size. This study explores a method for extending the plasma half-life of the N-terminal domain of TIMP2 (N-TIMP2) by appending it with a long, intrinsically unfolded tail containing Pro, Ala, and Thr (PATylation). We designed and produced two PATylated N-TIMP2 constructs with tail lengths of 100 and 200 amino acids (N-TIMP2-PAT100 and N-TIMP2-PAT200). Both constructs demonstrated higher apparent molecular weights and retained high inhibitory activity against MMP-9. N-TIMP2-PAT200 significantly increased plasma half-life in mice compared to the non-PATylated variant, enhancing its therapeutic potential. PATylation offers distinct advantages for half-life extension, such as fully genetic encoding, monodispersion, and biodegradability. It can be easily applied to N-TIMP2 variants engineered for high affinity and selectivity toward individual MMPs, creating promising candidates for drug development against MMP-related diseases.

Development and validation of a highly sensitive UPLC-MS/MS method for the determination of Huperzine A in rat plasma.

Huperzine A is a reversible and selective cholinesterase inhibitor and has been approved for the treatment of Alzheimer's diseases. In this study, we developed a highly sensitive and specific ulta-high-performance liquid chromatography-tandem mass spectrometry method for the determination of Huperzine A in rat plasma. An aliquot of 50 μL of rat plasma sample was pretreated with 200 μL of acetonitrile-methanol (v/v; 1:1) containing 0.2% formic acid followed by solid phase extraction. The resulting sample was separated on a Waters ACQUITY BEH C18 column using acetonitrile and water containing 0.2% formic acid as mobile phase, at a flow rate of 0.3mL/min. Multiple-reaction monitoring (MRM) mode was used for quantitative analysis of Huperzine A in positive electrospray ionization. In the concentration range of 0.01-10ng/mL, Huperzine A showed excellent linearity with correlation coefficient > 0.998. The intra- and inter-day RSD% were less than 9.7%, while the RE% ranged from -6.7% to 10.0%. The mean recovery was >84.5%. The validated method was demonstrated to be selective, sensitive, and reliable, which has been successfully applied to pharmacokinetic study of Huperzine A in rat plasma. Huperzine A displayed a long half-life in rat plasma and high oral bioavailability.

Reviewing The Latest Treatments for Haemophilia

Abstract: Advancements in haemophilia treatment have been significant in the first 20 years of the 21st century. However, the progress started with the fractionation of plasma in 1946. The first concentrates were developed after discovering FVIII in frozen plasma cryoprecipitate and FIX in the supernatant in the early 1960s, leading to initial attempts at replacement therapy. Unfortunately, due to the lack of screening methods for viral pathogens, people with haemophilia (PWH) received contaminated concentrates, leading to infections with the hepatitis A virus, hepatitis C virus, and human immunodeficiency virus. Thankfully, by 1985, viral screening methods and virucidal techniques were developed, making concentrates safe. The introduction of chromatography steps with monoclonal antibodies in the production process led to increasingly pure products. However, the problem of immunogenicity of administered concentrates persists. The development of alloantibodies against FVIII in a significant percentage of PWH is a serious adverse effect of replacement therapy. The next major advancement came with cloning the F8 and F9 genes, which allowed the production of factor concentrates using recombinant DNA technology. The injected FVIII and FIX molecules have a relatively short circulating half-life in the plasma of people with haemophilia A and B, approximately 12 and 18 hours, respectively. Methods such as conjugating the factor molecule with fragment crystallizable of IgG1, albumin, or adding polyethylene glycol have been applied to prolong the plasma half-life and extend the interval between injections, especially for risk. The next frontier in haemophilia therapy is the development of durable and potentially curative treatments, such as gene addition therapy. Experiments in haemophilia B have shown promising long-lasting responses. However, the results of gene therapy for haemophilia A have not been as remarkable, and the durability of the treatment is yet to be demonstrated. The long-term safety, predictability, durability, and efficacy of gene therapy for haemophilia A and B remain open questions. Currently, only healthy adult PWH has been enrolled in gene therapy clinical trials, and further studies are needed before gene therapy can be widely applied to children and those with pre-existing antibodies against the delivery vector.

Advances in Phytochemical-Based Nanocarrier Approaches for Rheumatoid Arthritis: Challenges and Scope for Future-generation Formulations

The study aims to investigate and assess the effectiveness of current novel techniques for the preparation of an efficient nanocarrier system in resolving the drawbacks associated with the delivery of herbal bioactives to treat rheumatoid arthritis. Systematic utilization of various search engines like Science Direct, Pubmed, Shodhganga, Google Scholar, and Google Patent databases based on various sets of key phrases has been performed. All the findings from these data have been studied and briefed based on their relevant and irrelevant information. The current study summarizes the existing research and development of new nano-formulations with a focus on herbal bioactive compounds for treating rheumatoid arthritis. Physicochemical properties of phytoconstituents, such as low aqueous solubility, low permeation coefficient, and chemical instability, poor bioavailability, short plasma half-life, and ultimately sub-therapeutic efficacy, limit their clinical translation despite their great potency. The utilization of Phytochemical-Based Nanocarrier Approaches for rheumatoid arthritis can be a milestone as a major population is affected by this disease worldwide. The intensive study recapitulates that novel drug delivery systems can provide new opportunities to efficiently deliver herbal bioactives with improved pharmacokinetic and pharmacodynamic properties. The exhaustive study concluded that transferosomes, ethosomes, transethosomes, niosomes, phytosomes, Solid Lipid Nanoparticles (SLN), Nano Lipid Carriers (NLC), bilosomes and hylurosomes are some of the efficient nanocarrier systems that may impart numerous benefits to the delivery of herbal bioactives for treatment of RA. These nanocarrier systems fabricated with phytoconstituents flaunt the evident promising benefits of improved aqueous solubility, low first-pass metabolism with upgraded bioavailability, sustained release action, resistance to enzymatic degradation etc. providing support in rheumatoid arthritis recovery. This review discusses that the upgradation of the pharmacological action and other relevant issues of herbal bioactives are possible by utilizing novel drug delivery systems, resulting in successful development of nano-loaded herbal bioactives. It also focuses on highlighting the pioneering progression in the field of herbal bioactives-loaded nanocarrier systems for rheumatoid arthritis both in vitro and in vivo along with their advanced preparation methods and applications and discussing the opportunities for further prospects. This compiled informative review will enlighten various researchers in the field of delivering herbal bioactives for rheumatoid arthritis.

Development of a high-yield recombinant clone for the enhanced production of a long-acting Glucagon like peptide-1 analogue with improved biological efficacy

Glucagon-like peptide-1 (GLP-1) analogues have demonstrated greater efficacy and safety in treating type 2 diabetes mellitus (T2DM) due to their strong ability to regulate hypoglycemia. The short plasma half-life of native GLP-1 has prompted the development of novel strategies, such as the conjugation of a C-16 fatty acid to lysine in the GLP-1 analogue sequence, to enhance its longevity. With the escalating burden of T2DM, there is a pressing need for the development of innovative GLP-1 analogues with enhanced efficacy and increased production capacities. In this study, we engineered three recombinant DNA-based clones by incorporating distinct upstream fusion tags, enzyme cleavage sites, and charge-based additional amino acid sequences. These constructed plasmids were subsequently transformed into E. coli BL21 DE3 hosts to enhance solubility and streamline downstream protein purification and were evaluated for yield, purity, and biological effectiveness. A high-yield clone was selected, and the peptide was purified using column chromatography, yielding 150–180 mg per Liter of fermentation culture. The purified C-16 fatty acid-conjugated GLP-1 analogue peptide was analysed for its biological activity, particularly cAMP generation in pancreatic β-cells. Results revealed a concentration of 10.58 pmol/mL of generated cAMP and an average 1.5-fold up-regulation of genes in the cAMP downstream pathway compared to the innovator standard. Based on these findings, we conclude that the developed clone, featuring the enterokinase cleavage site with a sequence of modified TrxA tag with five additional hydrophobic amino acids, not only enhances yield but also preserves the biological efficacy of the final product.

Development and validation of an LC-MS/MS method for the quantification of free and total doxorubicin in human plasma and its clinical application for a novel doxorubicin hydrochloride liposome injection in Chinese patients with breast cancer

AbstractA novel doxorubicin hydrochloride liposome injection was prepared to reduce toxicity and side effects, as well as extend plasma half-life in the treatment of breast cancer. In this study, a rapid and sensitive bioanalytical method was developed and validated to characterize the pharmacokinetic profile of total and free doxorubicin in plasma of 3 Chinese patients after intravenous infusion of this injection. Plasma samples were prepared by protein precipitation for the determination of total doxorubicin, while solid phase extraction was used to determine free doxorubicin. After plasma sample pre-treatment, total and free concentrations were quantified individually using a validated LC-MS/MS method. The calibration curves were found to be linear in the range of 0.20–500.0 ng mL−1 for total doxorubicin and in the range of 1.00–1,000 ng mL−1 for free doxorubicin. The free concentrations in plasma were only one sixth to one quarter of the total levels. Liposomal doxorubicin had a longer apparent half-life (&gt;50 h) than the non-targeted drug (&lt;10 h) reported in the reference. and a lower volume of distribution. This novel injectable formulation steadily released free doxorubicin from liposomes over a long period of time to reduce cardiac toxicity and side effects, while ensuring a clinical curative effect.

Bioavailability of a novel sustained-release pellet formulation of 5-flucytosine in healthy-fed participants for use in patients with cryptococcal meningitis.

Cryptococcal meningoencephalitis (CM) is an opportunistic fungal infection and a major cause of death among people living with human immunodeficiency virus in sub-Saharan Africa. 5-flucytosine (5-FC) is a unique, brain-permeable antifungal agent used to reduce mortality from CM and to prevent disease in individuals carrying cryptococcal antigen. 5-FC has a short plasma half-life, requiring 6-hourly oral dosing with an immediate-release (IR) formulation, a significant challenge in hospital and outpatient settings, risking a lack of compliance. We recently reported the relative bioavailability in fasting conditions of a sustained release (SR) oral pellet formulation of 5-FC. In this phase I study, we assessed the safety and pharmacokinetic profiles of the new 5-FC SR formulation in a single dose (2 × 3000 mg), relative to 5-FC IR tablets (Ancotil®; 1500 mg b.i.d.) in healthy participants in fed conditions. This randomized, two-period crossover study was conducted in South Africa to confirm the dose of the identified 5-FC SR formulation for a twice-daily 5-FC regimen in patients. Thirty-six healthy participants were included. All treatments were well tolerated and no serious adverse event was reported. Cmax and AUC(0-t) for the SR formulation (49.2 ± 10.49 μg/mL and 640.4 ± 126.4 h.μg/mL, respectively) were significantly higher than for the IR formulation (36.8 ± 7.61 μg/mL and 456.6 ± 72.8 h.μg/mL, respectively). A physiological based pharmacokinetic model (PBPK) predicted that under fasting conditions, 6000 mg SR pellets would show a good overlap with the IR product (3000 mg b.i.d), thus 6000 mg SR 5-FC b.i.d. in fasting conditions is recommended.

Thermosensitive Liposomes for Gemcitabine Delivery to Pancreatic Ductal Adenocarcinoma.

Treatment of pancreatic ductal adenocarcinoma with gemcitabine is limited by an increased desmoplasia, poor vascularization, and short plasma half-life. Heat-sensitive liposomes modified by polyethylene glycol (PEG; PEGylated liposomes) can increase plasma stability, reduce clearance, and decrease side effects. Nevertheless, translation of heat-sensitive liposomes to the clinic has been hindered by the low loading efficiency of gemcitabine and by the difficulty of inducing hyperthermia in vivo. This study was designed to investigate the effect of phospholipid content on the stability of liposomes at 37 °C and their release under hyperthermia conditions; this was accomplished by employing a two-stage heating approach. First the liposomes were heated at a fast rate, then they were transferred to a holding bath. Thermosensitive liposomes formulated with DPPC: DSPC: PEG2k (80:15:5, mole%) exhibited minimal release of carboxyfluorescein at 37 °C over 30 min, indicating stability under physiological conditions. However, upon exposure to hyperthermic conditions (43 °C and 45 °C), these liposomes demonstrated a rapid and significant release of their encapsulated content. The encapsulation efficiency for gemcitabine was calculated at 16.9%. Additionally, fluorescent analysis during the removal of unencapsulated gemcitabine revealed an increase in pH. In vitro tests with BxPC3 and KPC cell models showed that these thermosensitive liposomes induced a heat-dependent cytotoxic effect comparable to free gemcitabine at temperatures above 41 °C. This study highlights the effectiveness of the heating mechanism and cell models in understanding the current challenges in developing gemcitabine-loaded heat-sensitive liposomes.

Sequential recruitment of body fluid spaces for increasing volumes of crystalloid fluid.

The interstitial space harbours two fluid compartments linked serially to the plasma. This study explores conditions that lead to fluid accumulation in the most secluded compartment, termed the "third space". Retrospective data was collected from 326 experiments in which intravenous crystalloid fluid was administered to conscious volunteers as well as a small group of anaesthetized patients. The urinary excretion and plasma dilution derived from haemoglobin served as input variables in nine population volume kinetic analyses representing subtly different settings. An infusion of 250-500mL of Ringer's solution expanded only the central fluid space (plasma), whereas the infusion of 500-1,000mL extended into a rapidly exchanging interstitial fluid space. When more than 1L was infused over 30min, it was distributed across plasma and both interstitial fluid compartments. The remote space, characterized by slow turnover, abruptly accommodated fluid upon accumulation of 700-800mL in the rapidly exchanging space, equivalent to an 11%-13% volume increase. However, larger expansion was necessary to trigger this event in a perioperative setting. The plasma half-life of crystalloid fluid was 25 times longer when 2,000-2,700mL expanded all three fluid compartments compared to when only 250-500mL expanded the central space (14h versus 30min). As the volume of crystalloid fluid increases, it apparently occupies a larger proportion of the interstitial space. When more than 1L is administered at a high rate, there is expansion of a remote "third space", which considerably extends the intravascular half-life.

Gastroretentive Delivery Approach to Address pH-Dependent Degradation of (+)- and (-)-Phenserine.

(-)-Phenserine ("phenserine") and (+)-phenserine (posiphen; buntanetap) are longer-acting enantiomeric analogs of physostigmine with demonstrated promise in the treatment of Alzheimer's and Parkinson's diseases. Both enantiomers have short plasma half-lives, and their pharmacokinetics might be improved through the use of either once or twice-daily administration of an extended-release dosage form. Phenserine was observed to form a colored degradation product in near-neutral and alkaline pH environments, and at pH 7, the half-life of posiphen was determined to be ~ 9 h (40 °C). To limit luminal degradation which would reduce bioavailability, a gastroretentive tablet composed of a polyethylene oxide-xanthan gum matrix was developed. When placed in simulated gastric fluid (pH 1.2), approximately 70% of the phenserine was released over a 12 h period, and no degradants were detected in the release medium. In comparison, a traditional hydrophilic-matrix, extended-release tablet showed measurable amounts of phenserine degradation in a pH 7.2 medium over an 8 h release interval. These results confirm that a gastroretentive tablet can reduce the luminal degradation of phenserine or posiphen by limiting exposure to neutral pH conditions while providing sustained release of the drug over at least 12 h. Additional advantages of the gastroretentive tablet include reduced gastric and intestinal concentrations of the drug resulting from the slower release from the gastroretentive tablet whichmay also limit the occurrence of the dose-limiting GI side effects previously observed with immediate-release phenserine capsules.

Design, Synthesis, and In Vitro Characterization of Proteolytically-Stable Opioid-Neurotensin Hybrid Peptidomimetics.

Linking an opioid to a nonopioid pharmacophore represents a promising approach for reducing opioid-induced side effects during pain management. Herein, we describe the optimization of the previously reported opioid-neurotensin hybrids (OPNT-hybrids), SBL-OPNT-05 & -10, containing the μ-/δ-opioid agonist H-Dmt-d-Arg-Aba-β-Ala-NH2 and NT(8-13) analogs optimized for NTS2 affinity. In the present work, the constrained dipeptide Aba-β-Ala was modified to investigate the optimal linker length between the two pharmacophores, as well as the effect of expanding the aromatic moiety within constrained dipeptide analogs, via the inclusion of a naphthyl moiety. Additionally, the N-terminal Arg residue of the NT(8-13) pharmacophore was substituted with β3 hArg. For all analogs, affinity was determined at the MOP, DOP, NTS1, and NTS2 receptors. Several of the hybrid ligands showed a subnanomolar affinity for MOP, improved binding for DOP compared to SBL-OPNT-05 & -10, as well as an excellent NTS2-affinity with high selectivity over NTS1. Subsequently, the Gαi1 and β-arrestin-2 pathways were evaluated for all hybrids, along with their stability in rat plasma. Upon MOP activation, SBL-OPNT-13 and -18 were the least effective at recruiting β-arrestin-2 (E max = 17 and 12%, respectively), while both compounds were also found to be partial agonists at the Gαi1 pathway, despite improved potency compared to DAMGO. Importantly, these analogs also showed a half-life in rat plasma in excess of 48 h, making them valuable tools for future in vivo investigations.