Bioavailability Research Articles

Study on the crystallinity of PEG on the crystalline size of flavonoids in a crystalline dispersion system

Poor water solubility and low bioavailability of flavonoids present significant barriers to their development and application. To address these challenges, this study explores the use of crystalline solid dispersions (CSDs) to reduce drug crystalline size and enhance in vivo bioavailability. The CSDs were prepared using a spray-drying technique with chrysin (CHY) and quercetin (QUR) as model drugs and various molecular weights of polyethylene glycol (PEG) as carriers. The authors systematically investigated the factors influencing the interaction between flavonoids and PEG in CSDs. These factors included the relationships between intermolecular interactions and PEG molecular weight, crystallinity, microstructures such as crystalline domain size and crystal morphology of the flavonoids and PEG in CSDs, crystalline size of the drug in CSDs, and in vitro dissolution rate and in vivo pharmacokinetics. Our results indicated that the interaction between flavonoids and PEG in CSDs was influenced more by PEG crystallinity than by its molecular weight. Lower crystallinity of PEG, achieved through recrystallization, led to stronger intermolecular interactions with the drugs. Specifically, PEG8000 exhibited the lowest crystallinity, indicating a higher content of PEG in the amorphous state, which interacted more effectively with the amorphous drug in CSDs. This interaction significantly inhibited drug crystallization growth, resulting in a marked decrease in drug crystalline domain size and crystalline size. Consequently, PEG8000 was identified as the optimal carrier for preparing CSDs, achieving the best cumulative dissolution percentage. The QUR/PEG8000-CSD formulation increased the cumulative dissolution percentage and oral bioavailability of QUR by 18.76 and 20.66 times, respectively, compared to QUR alone. This study demonstrates that PEG crystallinity, following recrystallization, directly affects its intermolecular interactions with the drug, thereby impacting drug crystalline size and dissolution rate.

Anti-arthritic potential and antioxidant properties of infusion, fractions and flavonoid glycosides from Dipteryx alata (baru) leaves

Dipteryx alata Vogel., popularly known as "baru", is a native species of Brazilian cerrado used by "Ribeirinhos" in the North Araguaia microregion. In the traditional medicine, maceration of barks or leaves infusion are used to treat back and muscle pain, osteoporosis and rheumatism. However, few studies have demonstrated the pharmacological effects of this species. The goal of this study was to perform phytochemicals studies of lyophilized infusion of D. alata leaves (LI-DA), as well as obtaining ethyl acetate fraction (EAF-DA) and hydromethanolic fraction (HMF-DA), and isolated flavonoids. The antioxidant of LI-DA, EAF-DA and HMF-DA, anti-inflammatory effects of LI-DA and quercetin-3-O-β-glucoside-7-O-α-rhamnoside (DA-1) and quercetin-7-O-α-rhamnoside (DA-2) were performed while in silico tests were used for absorption, distribution, metabolism, excretion and toxicity predictions of DA-1 and DA-2. LI-DA, EAF-DA and HMF-DA were evaluated in antioxidant assays (2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid - ABTS; 2,2-diphenyl-1-picrylhydrazyl - DPPH; hydrogen peroxide - H2O2; reducing power and oxidation of β-carotene). The DA-1 and DA-2 were isolated from EAF-DA using chromatographic methods and characterized by Nuclear Magnetic Resonance (NMR) spectrometer. The Programs ProTox 3.0 and ADMETlab 2.0 were used for the prediction studies of DA-1 and DA-2. Mice received a single dose of LI-DA (3, 30, and 100 mg/kg), DA-1 (3 mg/kg) and DA-2 (3 mg/kg) and were subjected to inflammation induced by Complete Freund's Adjuvant (CFA) and in the zymosan-induced articular inflammation model. DA-1 and DA-2 have been identified for the first time in the leaves of D. alata. LI-DA, EAF-DA and HMF-DA demonstrated a high level of antioxidant activity as measured by ABTS (IC50 ≤ 5.62 μg/mL) and DPPH (IC50 ≤ 11.45 μg/mL). Oral administration of LI-DA (3, 30 and 100 mg/kg), DA-1 (3 mg/kg) and DA-2 (3 mg/kg) showed significantly reduced edema, cold and mechanical allodynia in the CFA-induced inflammation model (24 hours). LI-DA (3, 30, and 100 mg/kg) and DA-1 (3 mg/kg) reduced leukocytes migration into the joint cavity, mechanical allodynia, edema and NO production in mice (24 hours) in the zymosan-induced articular inflammation model. Additionally, DA-2 (3 mg/kg) reduced leukocyte migration and LI-DA (30 mg/kg) reduced protein exudation (24 hours) in zymosan model. DA-1 and DA-2 showed good oral bioavailability and low toxicity predicted by the ProTox model. This is the first chemical and biological study performed of D. alata infusion and two quercetin glycoside derivatives. The results indicated promising potential for the treatment of inflammation, pain, and rheumatism, supporting the traditional use of the infusion obtained from the leaves of D. alata.

Dissolution, phase behavior and mass transport of amorphous solid dispersions in aspirated human intestinal fluids

Amorphous solid dispersions (ASDs) typically show improved dissolution and generate supersaturated solutions, enhancing the oral bioavailability of poorly soluble drugs. To gain insights into intraluminal ASD behavior, we utilized two poorly soluble drugs with different crystallization tendencies, atazanavir and posaconazole, prepared as ASDs at a 10% drug loading with hydroxypropyl methylcellulose acetyl succinate (HPMCAS). We evaluated their release in aspirated fasted-state human intestinal fluid (FaHIF), and multi-component fasted-state simulated intestinal fluid (composite-FaSSIF), characterizing the supersaturation profiles and drug-rich nanodroplets that formed. Complete release was observed for atazanavir ASDs over a 90 min period. Flux for dissolved atazanavir ASDs remained high over the experimental time period of 3 h. In contrast, posaconazole solution concentrations were initially high and then decreased. Likewise, flux was initially high and then decreased where these changes are attributed to crystallization of the drug. Generation of spherical nano-sized amorphous droplets of ∼100-150 nm was found to occur in ex vivo FaHIF media for both ASDs, maximizing the diffusive flux during the supersaturation window. Moreover, buffer capacity differences were postulated to influence release rates of ASDs in simulated vs aspirated fluids. Importantly, the solution phase phenomena observed during ASD release in simulated fluids, namely amorphous nanodroplet formation and drug crystallization, were also found to occur in aspirated luminal fluids.

Preparation of curcumin-loaded chitosan/lecithin nanoparticles with increased anti-oxidant activity and in vivo bioavailability

As a natural polyphenol, curcumin (Cur) has exhibited a range of bioactive properties, including anti-inflammatory, anti-oxidant, and anti-infection properties. However, the chemical instability and low water solubility of Cur hinder its wide application. Herein, Cur-loaded chitosan/lecithin nanoparticles (CCL NPs) were prepared by the electrostatic self-assembly method. The prepared CCL NPs showed a small particle size (122.86 ± 1.53 nm) with homogeneous distribution (PDI = 0.17 ± 0.01). The high EE (79.34 ± 2.93 %) and LC (9.33 ± 0.34 %) indicated that most of Cur was encapsulated in CCL NPs. Meanwhile, the Cur was released from CCL NPs in a quick and sustained way after being exposed to simulated gastrointestinal fluids. The CCL NPs displayed superior anti-oxidant activity than that of free Cur. Moreover, the in vivo pharmacokinetic studies showed that the CCL NPs could lead to a ~ 2.64-fold increase in oral bioavailability compared with that of free Cur. All these findings indicated that the formation of CCL NPs would be a promising platform to deliver Cur in the food industry.

Pharmacokinetic Study of Fingolimod Nasal Films Administered via Nose-to-Brain Route in C57BL/6J Mice as Potential Treatment for Multiple Sclerosis.

Fingolimod hydrochloride (FH) has emerged as a vital medication for managing Multiple Sclerosis (MS). Despite its high oral bioavailability of 93%, it is plagued by slow oral absorption (Tmax = 8-12h) and extensive hepatic metabolism. Intranasal administration has emerged as an alternative to address these limitations, ensuring efficient central nervous system delivery and minimizing peripheral exposure and first-pass metabolism. This study aims to develop and evaluate FH nasal films for enhanced drug delivery. A Design of Experiments approach was employed to formulate FH nasal films, utilizing HPMC E50 as a film-forming polymer, PEG 400 as a plasticizer, and Me-β-CD as a permeation enhancer. Two formulations with superior in vitro and ex vivo performance were selected for in vivo evaluation. A comparative pharmacokinetic study was conducted in C57BL/6J mice in the brain and serum after administration of nasal films and oral FH solution, respectively. Sparse sampling and non-compartmental analysis were used. FH nasal films efficiently delivered the drug to both serum (Cmax(F3) = 0.35 ± 0.021, Cmax(F4) = 0.38 ± 0.029μg/mL) and brain (Cmax(F3) = 0.39 ± 0.05, Cmax(F4) = 0.44 ± 0.048μg/mL), achieving higher levels than oral delivery. Brain relative bioavailability (% Frel (0-6 h)) was 519% and 534%, while serum % Frel (0-6 h) was 295% and 343%. The rapid nose-to-brain delivery within 30min, in contrast to 10-h Tmax of the oral solution, indicates the potential of a combined IN and oral treatment regimen. This approach could expedite the attainment of steady-state concentrations, offering a promising method for managing multiple sclerosis (MS).

Absolute oral bioavailability of milvexian spray-dried dispersion formulation under fasted and fed conditions in healthy adult participants: An intravenous microtracer approach.

Milvexian is an oral, small-molecule factor XIa inhibitor being developed to prevent thromboembolic events. This study assessed the absolute bioavailability (F) of milvexian following single doses of milvexian spray-dried dispersion (SDD) formulation under fed and fasted conditions, and milvexian solution, in healthy adult participants using an intravenous microtracer approach. This was a phase I, open-label, partially randomized, 4-sequence, 5-period crossover study. After fasting for ≥10 h, participants received milvexian 200-mg oral solution with a 100-μg 14C milvexian intravenous microtracer at the time of maximum observed plasma concentration. Following a 3-day washout, participants were randomized to 1 of 4 milvexian SDD treatment sequences in a crossover fashion: 25 mg fasted, 25 mg fed, 200 mg fasted, or 200 mg fed. Pharmacokinetic data were collected up to 72 h postdose. Seventeen participants were dosed, and 14 completed treatment. Under fasted conditions, milvexian F was ~100%, 58.2%, and 54.2% following administration of the oral solution, 25 mg SDD, and 200 mg SDD, respectively. Under fed conditions, milvexian F following 25 mg and 200 mg SDD was 44.3% and 75.6%, respectively. The milvexian SDD formulation at 25 mg and 200 mg resulted in similar F in a fasted state; under fed conditions, milvexian F decreased at 25 mg and increased at 200 mg. These findings clarify pharmacokinetic-related gaps observed in previous studies.

Self-Nanoemulsifying Drug Delivery System of Morin: A New Approach for Combating Acute Alcohol Intoxication.

Acute alcohol intoxication (AAI) is a life-threatening medical condition resulting from excessive alcohol consumption. Our research revealed the potential of morin (MOR) in treating AAI. However, MOR's effectiveness against AAI was hindered by its poor solubility in water and low bioavailability. In this study, our aim was to develop a self-nanoemulsifying drug delivery system (SNEDDS) to enhance MOR's solubility and bioavailability, evaluate its anti-AAI effects, and investigate the underlying mechanism. The composition of MOR-loaded self-nanoemulsifying drug delivery system (MOR-SNEDDS) was determined by constructing pseudo-ternary phase diagrams, and its formulation proportion was optimized using the Box-Behnken design. Following characterization of MOR-SNEDDS, we investigated its pharmacokinetics and biodistribution in healthy animals. Additionally, we assessed the anti-AAI effects and gastric mucosal protection of MOR-SNEDDS in an AAI mice model, exploring potential mechanisms. After breaking down into tiny droplets, the optimized mixture of MOR-SNEDDS showed small droplet size on average, even distribution, strong stability, and permeability. Pharmacokinetic studies indicated that MOR-SNEDDS, compared to a MOR suspension, increased the area under the plasma concentration-time curve (AUC0-t) by 10.43 times. Additionally, studies on how drugs move and are distributed in the body showed that MOR-SNEDDS had an advantage in passively targeting the liver. Moreover, in a mouse model for alcohol addiction, MOR not only decreased alcohol levels by boosting the activity of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) in the stomach and liver, which counteracted the loss of righting reflex (LORR), but also reduced alcohol-induced damage to the stomach lining by lowering malondialdehyde (MDA) levels and increasing superoxide dismutase (SOD) levels. Furthermore, MOR-SNEDDS notably amplified these effects. MOR exhibits significant potential as a new medication for treating AAI, and utilizing MOR-SNEDDS with high oral bioavailability represents a promising new strategy in combating AAI.

Chitosan Oligosaccharide Modified Bovine Serum Albumin Nanoparticles for Improving Oral Bioavailability of Naringenin.

With the rapid development of nanotechnology, the research and development of nano-drugs have become one of the development directions of drug innovation. The encapsulation of the nanoparticles can change the biological distribution of the drug in vivo and improve the bioavailability of the drug in vivo. Naringenin is poorly soluble in water and has a low bioavailability, thus limiting its clinical application. The main purpose of this study was to develop a nano-sized preparation that could improve the oral bioavailability of naringenin. Chitosan oligosaccharide modified naringenin-loaded bovine serum albumin nanoparticles (BSA-COS@Nar NPs) were prepared by emulsification solvent evaporation and electrostatic interaction. The nanoparticles were characterized by HPLC, laser particle size analyzer, transmission electron microscope and X-ray diffraction analysis. The release in vitro was investigated, and the behavior of nanoparticles in rats was also studied. The caco-2 cell model was established in vitro to investigate the cytotoxicity and cellular uptake of nanoparticles. BSA-COS@Nar NPs were successfully prepared, and the first-order release model was confirmed in vitro release. In vivo pharmacokinetic results indicated that the area under the drug concentration- time curve (AUC) of BSA-COS@Nar NPs was 2.37 times more than free naringenin. Cytotoxicity and cellular uptake results showed that BSA-COS@Nar NPs had no significant cytotoxic effect on Caco- 2 cells and promoted cellular uptake of the drug. BSA-COS@Nar NPs could improve the in vivo bioavailability of naringenin.

ω-Carboxyl terminated cellulose esters are effective crystallization inhibitors for challenging drugs

Polymeric additives are widely used to delay drug crystallization from supersaturated solutions, which is critical for enhancing oral bioavailability by amorphous solid dispersion (ASD). The efficacy of these polymers relies on their capacity to inhibit nucleation and subsequent crystal growth. Drug nucleation is pivotal to crystallization; therefore, effective polymers are essential for suppressing nucleation from supersaturated solutions. We studied the performance of cellulose ω-carboxyalkanoates designed as crystallization inhibitors by measuring their influence on nucleation induction times of poorly soluble drugs celecoxib, posaconazole, and enzalutamide, from supersaturated solutions. In the absence of polymers, crystallization occurred within 5 to 15 minutes for all three drugs. Polymer hydrophobicity strongly influenced effectiveness in crystallization inhibition. Hydrophobic polymers prolonged induction times for up to 8 hours, while hydrophilic polymers were less effective, except for cellulose acetate glutarate (CA1.18-GA1.21; degrees of substitution acetate 1.18, glutarate 1.21). The cellulose ω-carboxyalkanoates had glass transition temperatures well above 100 °C, outstanding for ASD stability requirements. We investigated the impact of these designed polymers on surface tension and found that it only weakly influenced crystallization inhibition. Among the nine crafted cellulose derivatives, water-soluble CA1.18-GA1.21 emerged as a highly promising ASD polymer, preventing crystallization for 2-8 hours for all fast-crystallizing model compounds.

Mechanisms of dissolution and crystallization of amorphous glibenclamide

Amorphous solid dispersions enhance the dissolution and oral bioavailability of poorly water-soluble drugs. However, the link between polymer properties and formulation performance has not been fully clarified yet. We studied the effect of hydroxypropyl cellulose (HPC) polymers molecular weight (Mw) on the storage stability, dissolution kinetics and supersaturation stability of spray-dried amorphous glibenclamide (GLB) formulations. The solid-state stability of amorphous GLB during storage was significantly enhanced by both the 40 kDa (HPC-SSL) and 84 kDa (HPC-L) polymers, regardless of Mw differences. In contrast, HPC-SSL maintained significantly higher aqueous drug concentrations during dissolution, compared to HPC-L (its higher Mw analogue). Dedicated dissolution experiments, in situ optical microscopy and solid-state characterization revealed that aqueous drug concentrations were determined by the interplay between crystallization inhibition, drug ionization, wetting and solubilization effects: (1) HPC prevents surface nucleation, hence inhibiting crystallization, (2) intestinal colloids (bile salts and phospholipids) increase supersaturated drug concentrations via wetting and solubilization effects and (3) pH and drug ionization severely impact the degree of supersaturation. The better performance of the lower Mw HPC-SSL was due to its superior inhibition of surface crystallization. These insights into the molecular mechanisms of dissolution and crystallization of amorphous solids provide foundation for rational formulation development.

Study on the preparation of stabilizer-free silymarin nanocrystals and its oral absorption mechanisms

Many researchers have studied the oral absorption mechanisms yet, however, considering stabilizers often participate in the absorption process of nanocrystals, these known mechanisms may be incorrect. Hence in this study, we aimed to explore the correct absorption mechanism of nanocrystals by performing related studies on stabilizer-free nanocrystals. We firstly prepared stabilizer-free silymarin nanocrystals by high-pressure homogenization, and then performed absorption-related studies, such as solubility, dissolution rate, pharmacokinetic study, cellular uptake and intracellular transport. Results showed the stabilizer-free silymarin nanocrystals had an average particle size of (450.2 ± 4.46) nm, with PDI of 0.280 ± 0.021 and Zeta potential of −26.9 ± 2.4 mV. The conversion of silymarin crude drug to stabilizer-free silymarin nanocrystals increased the compound's solubility by 1.41 times, with a dissolution rate of 92.2 % in water within 30 min compared to 38.5 % for crude drugs. Pharmacokinetic studies showed the oral bioavailability of stabilizer-free silymarin nanocrystals was found to be 1.48 times greater than that of the crude drugs. The cell experimentation results demonstrated that the stabilizer-silymarin nanocrystals can improve uptake but have poor transmembrane transport properties. Most researchers believe that nanocrystals can enhance transmembrane transport of drugs via an endocytosis-mediated pathway. In fact, nanocrystals are indeed endocytosed more by the cells, but this transport pathway is poor because the cells lack the intracellular transport pathway to transport nanocrystals from the AP side to the BP side. Therefore, we believe that the intracellular transport of nanocrystals can be enhanced by modifications and other carriers if needed to improve nanocrystals' ability to promote oral absorption.

Fragment Addition-Based Design of Heteroaromatic-Biphenyl-DAPYs as Potent and Orally Available Non-nucleoside Reverse Transcriptase Inhibitors Featuring Significantly Enhanced Safety.

Our previously disclosed biphenyl-DAPY 3 emerged as a potent inhibitor against WT HIV-1 and various mutant strains. Yet, its journey toward clinical application was thwarted by pronounced cytotoxicity and low selectivity (CC50 = 6 μM, SI = 3515). The safety improvement approach we employed in this work entailed the incorporation of diverse heteroaromatic substituents at the C5 position to exploit the tolerant regions of the NNRTIs' binding pocket through fragment addition-based drug design strategy, ultimately leading to the identification of a series of novel heteroaromatic-biphenyl-DAPYs. The exemplary compound 10d revealed a striking reduction in cytotoxicity (CC50 > 272.81 μM), nearly 45.5 times lower than 3, while showcasing 15-fold increase in selectivity (SI > 52632). This analog sustained exceptional anti-HIV-1 activity against both WT HIV-1 (EC50 = 5 nM) and various mutant strains. Compared to 3, a markedly slower rate of metabolism in human liver microsomes of 10d was observed. Its pharmacokinetic profile was equally captivating, featuring excellent oral bioavailability (F = 57.4%). Moreover, 10d exhibited a delicate sensitivity toward CYP, minimal inhibition of hERG, and no detectable acute toxicity in vivo. These enchanting findings illuminated the potential of 10d as a promising candidate for HIV-1 therapy.

Impact of dissolution medium pH and ionization state of the drug on the release performance of amorphous solid dispersions

Amorphous solid dispersions (ASDs) are widely employed as a strategy to improve oral bioavailability of poorly water soluble compounds. Typically, optimal dissolution performance from a polyvinylpyrrolidone vinyl acetate (PVPVA) based ASD is observed at relatively low drug loading limit. Above a certain drug load, termed limit of congruency (LoC), the release from ASDs significantly decreases. So far, the majority of the dissolution behavior has been tested in conditions where the drug primarily exists in unionized form. In this work, the impact of pH of the dissolution environment on the release performance of ASDs of an ionizable drug was studied. Atazanavir (ATZ), a weakly basic drug with a pKa of 4.5 was used as a model compound and PVPVA was used as a non-ionizable matrix polymer. Dissolution rate was measured using Wood's apparatus which normalizes the surface area of the dissolving tablet. The pH of the dissolution media was varied between 1 and 6.8, cover a range where ATZ exists as >99% ionized or unionized species. At pH 6.8, near complete release was observed only when the drug load was ≤ 6%. Unlike typically observed drastic decline in release behavior for PVPVA based ASDs above LoC, ATZ ASDs underwent gradual decline in dissolution behavior when the DL was increased to 8%. This was attributed to potential formation of an ATZ-PVPVA associated phase with dissolution rate slower than neat PVPVA. However, the 10% DL ASD showed negligible ATZ release. On another extreme (pH 1) where ATZ is ∼100% ionized, the dissolution rate of ATZ was faster than that of PVPVA. ASD dissolution rate was found to be slower than that of the neat drug but faster than PVPVA and interestingly, did not change with DL. This can be attributed to formation of an ionized ATZ-PVPVA phase which controls the dissolution rate of the ASD. At pH 3, where the drug is ∼97% ionized, near complete release was observed for drug loads ≤ 8%. To observe significant increase in drug loading with near complete release, >98% ionization of ATZ was required. At pH 2 where ATZ is ∼99.7% ionized, near complete release was observed for drug loads up to 30%. Furthermore, the deterioration in dissolution performance with an increase in drug load continued to be gradual at pH 2. The enhancement in dissolution performance did not correlate with solubility enhancement of ATZ due to ionization. We theorize that the enhancement in the dissolution performance due to ionization is the result of formation of an ionized ATZ-PVPVA phase which increases the hydrophilicity and the miscibility of the ASD. This can help resist water induced phase separation during ASD dissolution and therefore, result in continuous, and congruent dissolution of the drug and polymer.

Lead Toxicity From Imported Jewelry.

We summarize here the presentation and course of lead poisoning in a 1-year-old who ingested a lead-containing metallic medallion from India. We analyzed the medallion to determine its composition, using x-ray fluorescence spectroscopy and field emission scanning electron microscopy. A simple extraction test was used to estimate oral bioavailability. We used the US Environmental Protection Agency Integrated Exposure Uptake Biokinetic model to compare actual versus predicted blood lead levels. X-ray fluorescence analysis revealed the composition of the medallion to be: Lead 155 000 ppm (15%), copper 530 000 ppm (53%), nickel 49 000 ppm (4.9%), arsenic 22 000 ppm (2.2%), antimony 12 000 ppm (1.2%), tin 3000 ppm (0.3%), and silver 1300 ppm (0.13%). With a fixed ingestion of 7786 µg/d (estimated by simulated gastric extraction analysis) and assuming 50% bioavailability, Integrated Exposure Uptake Biokinetic modeling predicted the geometric mean blood lead level would increase from 2.05 µg/dL to 173.9 µg/dL. This patient had potentially life-threatening lead poisoning from an ingested piece of jewelry. The medallion contained 550 times the allowable content of lead in children's metallic jewelry sold in the United States. This case highlights the ubiquitous nature of lead in our global environment and the risk of exposure to novel sources, especially for children.

Integrating schiff base ligands with diorganotin(IV) metal: Crystallographic insights and biological potency against malaria and oxidative stress

Amidst the ongoing search for potent antimalarial agents, this research focuses on synthesizing and analyzing diorganotin(IV) complexes (3–10) with Schiff base ligands (1–2) derived from 2-amino-4‑tert-butylphenol and salicylaldehyde derivatives, revealing compelling medicinal applications. Comprehensive structural characterization of these compounds was conducted using a suite of analytical techniques, including FT-IR, NMR (1H, 13C and 119Sn), SEM-EDAX, TGA and mass spectrometry. These analyses unequivocally confirmed that the ligands coordinate to the diorganotin(IV) ion via oxygen and nitrogen donor sites in an iminol configuration, indicating a pentacoordinated stereochemistry. Furthermore, to confirm the complexes structural characteristics, SC-XRD was performed on the complex 7 [Me₂SnL2] which indicated that the compound crystallizes in a monoclinic system with distorted square pyramidal stereochemistry. Biological evaluations states that the complexes have superior biological activities compared to their respective ligands with the order of activity being: Ph2SnL1–2>Bu2SnL1−2>Et2SnL1−2>Me2SnL1−2. Complexes (6, 10) showed significant antimalarial and antioxidant efficacy, with IC50 values of 0.99 ± 0.18 - 1.69 ± 0.15 µM and 2.36 ± 0.05 - 3.16 ± 0.02 µM, respectively, comparable to standard therapeutic agents. ADMET lab 2.0 evaluation confirmed their adherence to Lipinski's Rule of Five and strong pharmacokinetic properties, including oral bioavailability, permeability and clearance, similar to standard drugs.

Low-melting mixture solvents as novel solubilizing agents: Improving tolvaptan formulation and therapeutic efficacy

Presently, a significant number of pharmaceutical drugs exhibit poor solubility in water and fall within categories II and IV of the biopharmaceutical classification system. This predicament has prompted the exploration for novel solvents or excipients to enhance the solubility and bioavailability of the active compounds in aqueous environments. Low-melting mixture solvents (LoMMSs) have gained recognition as potential solvents for active pharmaceutical ingredients to improve therapeutic efficacy and delivery. This study focuses on the preparation of a eutectic mixture composed of betaine, malic acid, proline, and water (BE-MA-PR-WA) to enhance the formulation options for tolvaptan, an FDA-approved medication used to treat acute congestive heart failure, which has limited solubility in aqueous solutions. The findings presented in this article represent the first reported results on the administration of LoMMS-solubilized tolvaptan. Furthermore, an examination of the solubility and bioavailability of tolvaptan utilizing this mixture was conducted, alongside an assessment of its toxicity. The solubility of tolvaptan in BE-MA-PR-WA (1:1:1:7) increased 483 times compared to solubility in water. Toxicity studies indicated that the LoMMS formulation BE-MA-PR-WA was safe for oral administration. The oral bioavailability of tolvaptan was significantly increased by 1.9-fold in the BE-MA-PR-WA than that in water. In addition, the 5-hour urine volume of rats indicated that BE-MA-PR-WA also enhanced the diuretic effects of tolvaptan in rats. The findings suggest that BE-MA-PR-WA enhance the solubility and bioavailability of tolvaptan, and are deemed non-toxic. Consequently, LoMMS may be deemed promising solubilizing agents, potentially facilitating the absorption of poorly bioavailable medications.

Microwave-assisted, sulfhydryl-modified β-cyclodextrin-silymarin inclusion complex: A diverse approach to improve oral drug bioavailability via enhanced mucoadhesion and permeation

The current study aimed to generate a sulfhydryl-modified β-cyclodextrin-silymarin complex (sulfhydryl-modified β-CD-SMN complex) and to evaluate the enchantment in solubility, permeability, and bioavailability of a model BCS Class IV drug silymarin (SMN). For this purpose, sulfhydryl-modified β-CD was synthesized by replacing all primary and secondary –OH groups at the β-CD backbone with sulfhydryl groups via a novel microwave-assisted technique. Afterward, sulfhydryl-modified β-CD was complexed with silymarin and characterized by FTIR and 1H NMR spectroscopy. Moreover, no. of sulfhydryl groups and their oxidative stability, solubility, safety, mucoadhesion, release, diffusion, and rheological studies were performed. Furthermore, in-vivo studies were conducted to confirm enhanced pharmacokinetic properties of silymarin. Sulfhydryl-modified β-CD showed 8291 ± 418 μmol/g sulfhydryl groups that were prone to oxidation at pH ≥ 5, however, most of the sulfhydryl groups were found stable at pH 4 having a pKa value of 8.3. Modified β-CD oligomer showed improved solubility of SMN, significantly enhanced drug transport across goat intestinal mucosa, 78-fold improved mucoadhesion, improved drug dissolution and 4.4-fold enhanced dynamic viscosity. No toxic effects were reported to Caco-2 cells at 0.5 % (m/v) concentration of sulfhydryl-modified β-CD for 24 h. The apparent permeability coefficient (Papp) of SMN was 6.9-fold enhanced on goat intestinal mucosa. Moreover, in-vivo studies confirmed a significantly enhanced oral bioavailability of SMN due to combination with sulfhydryl-modified β-CD. Based on these findings, the sulfhydryl-modified β-CD-silymarin inclusion complex can be a promising technique to enhance the bioavailability of BCS Class IV drugs via enhanced solubility, mucoadhesion, and permeability triple action.

Metal-organic framework-edaravone nanoparticles for radiotherapy-induced brain injury treatment

Cranial radiotherapy may cause damage to normal brain tissues and induce cognitive dysfunction, so developing an effective strategy to prevent radiotherapy-induced brain injury is essential. Metal-organic frameworks (MOFs) can be used as vectors for the delivery of neuroprotective drugs due to their high drug loading capacity and low toxicity. In this study, we synthesized MIL-53(Cr) nanoparticles, which were used to deliver edaravone, and modified the surface of the nanoparticles with polyethylene glycol and Angiopep-2 (EDA@MIL-53(Cr)–P/A) to improve their oral bioavailability and ability to cross the blood–brain barrier (BBB). We confirmed that MIL-53(Cr)–P/A nanoparticles could achieve the sustained release of edaravone and enhance its ability to cross the BBB. The results of in vitro experiments showed that EDA@MIL-53(Cr)–P/A could exert radioprotective effects on HT22 and BV2 cells. We also demonstrated that EDA@MIL-53(Cr)–P/A could alleviate brain injury and cognitive dysfunction in mice receiving whole-brain irradiation. Mechanistically, EDA@MIL-53(Cr)–P/A alleviated irradiation-induced brain damage by inhibiting oxidative stress, DNA damage, apoptosis and inflammatory reactions. This study provides a new strategy for the protection against radiotherapy-induced brain injury.

Selective and Orally Bioavailable c-Met PROTACs for the Treatment of c-Met-Addicted Cancer.

c-Met is an attractive therapeutic target in multiple tumors. Previous studies have discovered some effective proteolysis-targeting chimeras (PROTACs) able to degrade c-Met; however, the structure-activity relationship (SAR), degradation selectivity, and pharmacokinetic profiles of c-Met PROTACs have, to date, remained largely unknown. Herein, through extensive SAR studies on various warheads, linkers, and E3 ligase ligands, a novel potent c-Met PROTAC Met-DD4 was identified. Our results suggested that Met-DD4 could induce robust c-Met degradation with excellent selectivity (DC50 = 6.21 nM), substantially killing the c-Met-addicted cancer cells (IC50 = 4.37 nM). Furthermore, in vivo studies showed that Met-DD4 could achieve excellent oral bioavailability and c-Met degradation, strongly retarding tumor growth with minute organ toxicity. Overall, this study reveals that targeted degradation of c-Met is a promising strategy for the treatment of c-Met-addicted cancers and provides novel lead compounds for the clinical translation of c-Met PROTACs.

Encapsulation of astaxanthin in OSA-starch based amorphous solid dispersions with HPMCAS-HF/Soluplus® as effective recrystallization inhibitor

In this study, the interaction among multifunctional excipients, including polysaccharides, cellulose derivatives, and surfactants, was particularly investigated, together with its impact on the physicochemical properties of astaxanthin amorphous solid dispersions (ASTX ASDs). It was indicated that Span 20 could rapidly form hemimicelles or aggregates in the presence of hypromellose acetate succinate HF (HPMCAS-HF, HF) or Soluplus®, while octenyl succinic anhydride modified starch (OSA-starch) efficiently assisted in the coalescence inhibition of drug-excipients aggregates, which was jointly beneficial to the recrystallization inhibition of amorphous ASTX. ASTX ASDs were further prepared with OSA-starch, HPMCAS-HF/Soluplus®, and Span 20 as the wall materials. DSC, SEM, and XRD confirmed that crystalline ASTX had transformed to amorphous state in the ASDs, while FT-IR spectra provided evidence suggesting the existence of hydrogen bonds and hydrophobic interaction between ASTX and the excipients. The dissolution of ASTX ASDs in different media revealed significant promotion, while the pharmacokinetic results further demonstrated the oral bioavailability of ASTX ASDs enhanced remarkably, exhibiting 2.75-fold (SD1) and 1.87-fold (SD2) increase, respectively, compared to ASTX bulk powder. In summary, the cellulose derivatives-surfactant interaction had great impact on the physicochemical properties of ASTX ASDs, and their combinations exhibited great potential for delivering the hydrophobic bioactive compounds efficiently.