Formulation and particle size reduction improve bioavailability of poorly water-soluble compounds with antimalarial activity

Evaluating the role of amino acids and isothermal dry particle coating in modulating buccal permeation of large molecule drug vancomycin

The formulation and delivery of macromolecules through the oral route pose considerable challenges due to factors such as large molecular weight, pH sensitivity, and limited formulation approaches. This challenge is compounded if the drug is poorly permeable, necessitating innovative drug delivery strategies. Vancomycin, a widely prescribed glycopeptide antibiotic, has an oral bioavailability of less than 10%, leading to predominantly intravenous administration and potential patient discomfort. This study explores the potential of the buccal route as a non-invasive, highly vascularised alternative route of administration, offering a rapid onset of action while bypassing the first-pass metabolism. In this study, vancomycin was coated with L-glutamic acid using an isothermal dry particle coater to modulate permeation through the buccal cell line, TR146. Results confirm significant impact of both amino acid concentration and dry particle coating on the rate and extent of drug permeability. With the introduction of L-glutamic acid and utilisation of the isothermal dry particle coater, vancomycin's permeation profile increased six-fold compared to the control due to the formation of drug ion-pair complex. Imaging studies showed the presence of layered micronized glutamic acid particles on the surface of dry coated vancomycin particles which confirms the role of dry coating and amino acid concentration in modulating drug permeation. Microbiology experiments in Staphylococcus aureus, minimum inhibitory concentration and biofilm disruption studies, provided confirmatory evidence of antimicrobial activity of dry coated glutamic acid-vancomycin ion pair particulate structure. This study demonstrates, for the first-time, buccal delivery of dry coated large molecule drug, vancomycin, through controlled deposition of amino acid using innovative particle coating strategy.

Preparation, Characterization, and Evaluation of Physcion Nanoparticles for Enhanced Oral Bioavailability: An Attempt to Improve Its Antioxidant and Anticancer Potential

This study aims to enhance the dissolution rate of a poorly water-soluble drug physcion by producing its nanoparticles (NPs) using an antisolvent precipitation with a syringe pump (APSP) method and to assess its antioxidant and cytotoxic potential. The NPs were prepared using a simple and cost-effective APSP method and subsequently characterized by different analytical techniques including dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray powder diffractometry (XRD). They were also subjected to solubility and dissolution studies, and different parameters such as dissolution efficiency (DE), mean dissolution time (MDT), and difference (f1) and similarity factors (f2) were determined. Furthermore, physcion and its NPs were investigated for antioxidant and cytotoxic effects using various in vitro assays. SEM and DLS analysis indicated that the average size of physcion NPs was 110 and 195 ± 5.6 nm, respectively. The average ζ-potential and polydispersibility index (PDI) of the prepared NPs were -22.5 mV and 0.18, respectively, showing excellent dispersibility. XRD confirmed the amorphous nature of physcion NPs. The solubility and dissolution rates of NPs were significantly higher than those of the original powder. The antioxidant potential studied by the (DPPH), FRAP, and H2O2 assays was greater for physcion NPs than that for the raw powder. The IC50 values of physcion NPs against the aforementioned models were 57.56, 22.30, and 22.68 μg/mL, respectively. Likewise, the cytotoxic potential investigated through the MTT assay showed that physcion NPs were more cytotoxic to cancer cell lines A549 (IC50 4.12 μg/mL), HepG2 (IC50 2.84 μg/mL), and MDA-MB-231 (IC50 2.97 μg/mL), while it had less effect on HPAEpiC (IC50 8.68 μg/mL) and HRPTEpiC (IC50 10.71 μg/mL) normal human epithelial cells. These findings have proved that the APSP method successfully produced physcion NPs with enhanced solubility, dissolution rate, and antioxidant and cytotoxic activities.

Ocular Delivery of Quercetin Using Microemulsion System: Design, Characterization, and Ex-vivo Transcorneal Permeation

Background

The goal of this research was to design and characterize quercetin microemulsions (MEs) to resolve water solubility issues related to quercetin and improve transcorneal permeation into the eye.

Methods

MEs were prepared by the phase diagram method. Oily phase (oleic acid-Transcutol P), surfactant (Tween 80, Span 20), and co-surfactant (propylene glycol) were used to make a quercetin-loaded ME. The size of the droplets, their viscosity, pH, release, flux, and diffusivity were all measured.

Results

Droplet diameters in ME samples ranged from 5.31 to 26.07 nanometers. The pH varied from 5.22 to 6.20, and the release test revealed that 98.06 percent of the medication was released during the first 24 hours. The flux and diffusivity coefficients of the ME-QU-8 formulation were 58.8 µg/cm².h and 0.009 cm²/h, respectively, which were 8.8 and 17.9 times greater than the quercetin aqueous control (0.2 percent). The maximum percentage of drug permeated through rabbit cornea after five hours was 16.11%.

Conclusions

It is concluded that ME containing quercetin could increase transcorneal permeation and that permeation could be altered by any change in the composition of the ME formulation. This effect might be caused by structural alterations in the cornea caused by ME components.

The evaluation of ADME and pharmacokinetic properties of decoquinate derivatives for the treatment of malaria

The emergence of Plasmodium falciparum (Pf) parasite strains tolerant of the artemisinin component and resistant to the other drug component in artemisinin combination therapies (ACTs) used for treatment now markedly complicates malaria control. Thus, development of new combination therapies are urgently required. For the non-artemisinin component, the quinolone ester decoquinate (DQ) that possesses potent activities against blood stage Pf and acts on a distinct target, namely the Pf cytochrome bc₁ complex, was first considered. However, DQ has poor drug properties including high lipophilicity and exceedingly poor aqueous solubility (0.06 μg/ml), rendering it difficult to administer. Thus, DQ was chemically modified to provide the secondary amide derivative RMB005 and the quinoline O-carbamate derivatives RMB059 and RMB060. The last possesses sub-nanomolar activities against multidrug resistant blood stages of Pf, and P. berghei sporozoite liver stages. Here we present the results of ADME analyses in vitro and pharmacokinetic analyses using C57BL/6 mice. The amide RMB005 had a maximum mean whole blood concentration of 0.49 ± 0.02 µM following oral administration; however, the area under the curve (AUC), elimination half-life (t_1/2) and bioavailability (BA) were not significantly better than those of DQ. Surprisingly, the quinoline O-carbamates which can be recrystallized without decomposition were rapidly converted into DQ in human plasma and blood samples. The maximum concentrations of DQ reached after oral administration of RMB059 and RMB060 were 0.23 ± 0.05 and 0.11 ± 0.01 µM, the DQ elimination half-lives were 4.79 ± 1.66 and 4.66 ± 1.16 h, and the DQ clearance were 19.40 ± 3.14 and 21.50 ± 3.38 respectively. Under these assay conditions, the BA of DQ could not be calculated Overall although RMB059 and -060 are labile in physiological medium with respect to the DQ parent, the potential to apply these as prodrugs is apparent from the current data coupled with their ease of preparation.

Molecular Docking of Gallic Acid and Its Derivatives as the Potential nNOS Inhibitors

The global prevalence of anxiety and depression rates have increased by 25% due to the impact of the COVID-19 pandemic. Depression can occur due to an increase in NO produced by the nNOS enzyme. Gallic acid and its derivatives can be obtained from nature and have various biological activities. This study aimed to determine the potential of gallic acid and its derivatives as nNOS inhibitors using the molecular docking method with parameters of binding energy values, RMSD values, and specific binding to amino acid residues. The results showed that gallic acid, 4-O-methyl gallic acid, and epigallocatechin gallate had bond energies of −1.87; −2.36; and −0.12 kcal/mol, respectively. Compared to the standard ligand, which had binding energy of −2.84 kcal/mol, gallic acid 4-O-(6-galloyl glucoside) had binding energy of −4.12 kcal/mol. Based on these results, gallic acid 4-O-(6-galloyl glucoside) can potentially inhibit nNOS.

Chemical and Pharmacological Properties of Decoquinate: A Review of Its Pharmaceutical Potential and Future Perspectives

Decoquinate (DQ) is an antimicrobial agent commonly used as a feed additive for birds for human consumption. Its use as an additive is well established, but DQ has the potential for therapy as an antimicrobial drug for veterinary treatment and its optimized derivatives and/or formulations, mainly nanoformulations, have antimicrobial activity against pathogens that infect humans. However, DQ has a high partition coefficient and low solubility in aqueous fluids, and these biopharmaceutical properties have limited its use in humans. In this review, we highlight the antimicrobial activity and pharmacokinetic properties of DQ and highlight the solutions currently under investigation to overcome these drawbacks. A literature search was conducted focusing on the use of decoquinate against various infectious diseases in humans and animals. The search was conducted in several databases, including scientific and patent databases. Pharmaceutical nanotechnology and medicinal chemistry are the tools of choice to achieve human applications, and most of these applications have been able to improve the biopharmaceutical properties and pharmacokinetic profile of DQ. Based on the results presented here, DQ prototypes could be tested in clinical trials for human application in the coming years.

Preparation of Decoquinate Solid Dispersion by Hot-Melt Extrusion as an Oral Dosage Form Targeting Liver-Stage Plasmodium Infection

Liver-stage Plasmodium in humans is an early stage of malarial infection. Decoquinate (DQ) has a potent multistage antimalarial activity. However, it is practically water insoluble. In this study, the hot-melt extrusion (HME) approach was employed to prepare solid dispersions of DQ to improve oral bioavailability. The DQ dispersions were homogeneous in an aqueous suspension that contained most DQ (>90%) in the aqueous phase. Soluplus, a solubilizer, was found compatible with DQ in forming nanoparticle formulations during the HME process. Another excipient HPMC AS-126 was also proven to be suitable for making DQ nanoparticles through HME. Particle size and antimalarial activity of HME DQ suspensions remained almost unchanged after storage at 4°C for over a year. HME DQ was highly effective at inhibiting Plasmodium infection in vitro at both the liver stage and blood stage. HME DQ at 3 mg/kg by oral administration effectively prevented Plasmodium infection in mice inoculated with Plasmodium berghei sporozoites. Orally administered HME DQ at 2,000 mg/kg to mice showed no obvious adverse effects. HME DQ at 20 mg/kg orally administered to rats displayed characteristic distributions of DQ in the blood with most DQ in the blood cells, revealing the permeability of HME DQ into the cells in relation to its antimalarial activity. The DQ dispersions may be further developed as an oral formulation targeting Plasmodium infection at the liver stage.

Decoquinate liposomes: highly effective clearance of Plasmodium parasites causing severe malaria

Background

Severe malaria caused by Plasmodium falciparum leads to most malaria-related deaths globally. Decoquinate (DQ) displays strong activity against multistage infection by Plasmodium parasites. However, the development of DQ as an oral dosage form for the treatment of malaria at the blood stage has not been successful. In this study, liposome formulations of DQ were created for intravenous (IV) injection to suppress Plasmodium berghei, a parasite that causes severe malaria in mice.

Methods

DQ liposomes were prepared by conventional ethanol injection method with slight modifications and encapsulation efficiency evaluated by the well-established centrifugation method. Potency of the DQ liposomes against P. falciparum was assessed in vitro using freshly isolated human red blood cells. The efficacy of the DQ liposomes was examined in the mouse model of severe malaria.

Results

The DQ liposomes were around 150 nm in size and had the encapsulation efficiency rates > 95%. The freshly prepared and lyophilized liposomes were stable after storage at − 20 °C for 6 months. The liposomes were shown to have excellent activity against P. falciparum in vitro with DQ IC₅₀ 0.91 ± 0.05 nM for 3D7 (chloroquine sensitive strain) and DQ IC₅₀ 1.33 ± 0.14 nM for Dd2 (multidrug resistant strain), which were 18- and 14-fold more potent than artemisinin, respectively. Mice did not have any signs of toxicity after receiving high dose of the liposomes (DQ 500 mg/kg per mouse) by IV injection. In the mouse model of severe malaria, the liposomes had impressive efficacy against P. berghei with DQ ED₅₀ of 0.720 mg/kg.

Conclusion

The DQ liposomes prepared in this study were stable for long term storage and safe for IV injection in mammalian animals. The newly created liposome formulations had excellent activity against Plasmodium infection at the blood-stage, which encourages their application in the treatment of severe malaria.

Preparation and Pharmacokinetic Characterization of an Anti-Virulence Compound Nanosuspensions

Antibiotic resistance has become a worldwide public health threat due to the rapid evolution and spread of antibiotic-resistant bacteria. CCG-211790 is a novel anti-virulence compound that does not kill bacteria but could ameliorate human diseases by inhibiting expression of virulence factors, thereby applying less selection pressure for antibiotic resistance. However, its potential clinical use is restricted because of its poor aqueous solubility, resulting in formulation challenges. Nanosuspension technology is an effective way to circumvent this problem. Nanosuspensions of CCG-211790 with two different particle sizes, NanoA (315 ± 6 nm) and NanoB (915 ± 24 nm), were prepared using an antisolvent precipitation-ultrasonication method with Tween 80 as the stabilizer. Particle and pharmacokinetics (PK) of CCG-211790 nanosuspensions were characterized. Both NanoA and NanoB demonstrated remarkable increases in dissolution rate compared with the bulk compound. The PK parameters of NanoA were comparable to those of CCG-211790 solution formulation in intravenous or oral administration, suggesting that CCG-211790 nanosuspensions with smaller particle size improved oral bioavailability and drug exposure compared to traditional formulations of drug candidates.

An in vitro ADME and in vivo Pharmacokinetic Study of Novel TB-Active Decoquinate Derivatives

Tuberculosis (TB) is currently the leading cause of mortality due to an infectious disease, despite the existence of multiple effective first-line and second-line drugs. The current anti-TB regimen requires a prolonged treatment period of around 6 months and is only efficacious against drug-sensitive strains of Mycobacterium tuberculosis (Mtb). With a rise in cases of multi-drug resistant and extensively drug resistant strains of Mtb, newer treatments comprising compounds with novel mechanisms of action are required. Although decoquinate (DQ) is inactive against Mtb, its derivatives are of interest to anti-TB drug discovery because of their potential to permeate the mycobacterial cell wall, Mtb-infected macrophages, and granulomatous lesions by passive diffusion. The compounds also display mechanisms of action which are unlike those of currently used quinolones, potentially displaying activity against new targets. Three such derivatives bearing an alkyl group at N-1 and an amide group at C-3 (RMB 041, -043, and -073) displayed potent in vitro activities against Mtb H37Rv (90% minimum inhibitory concentrations, MIC90 = 1.61, 4.18, and 1.88 μM, respectively) and high selectivity indices (10-25). In this study, we evaluated the drug-like properties (in vitro microsomal stability, microsomal/plasma protein binding, kinetic solubility, lipophilicity, and passive permeability) and pharmacokinetic (PK) parameters of these compounds after intravenous and oral administration to male C57BL/6 mice. The compounds showed markedly improved kinetic solubilities compared to that of the parental DQ and were metabolically stable in vitro. The maximum concentrations reached after oral administration were 5.4 ± 0.40, 5.6 ± 1.40, and 2.0 ± 0.03 μM; elimination half-lives were 23.4 ± 2.50, 6.2 ± 0.80, and 11.6 ± 1.30 h; and bioavailabilities were 21.4 ± 1.0, 22.1 ± 2.2, and 5.9 ± 1.3 for RMB041, -043, and -073, respectively. These compounds therefore display promising drug-like properties, and their PK/toxicity profiles (including long half-lives both in vitro and in vivo) support their potential as candidates for further investigation in animal models of Mtb infection.

Effect of finasteride particle size reduction on its pharmacokinetic, tissue distribution and cellular permeation

Finasteride (FSD), a specific competitive inhibitor of the steroid type-II 5α-reductase enzyme, is used in treatment of benign prostate hyperplasia (BPH) and male pattern baldness. The drug is of limited solubility that affect its dissolution and bioavailability. The aim was to study the effect of FSD particle size reduction on the pharmacokinetic, tissue distribution and cellular permeation. An optimized drug micro- and nano-particles were developed, characterized, administered to group of rats, and systemic pharmacokinetic and tissue distribution within target and not-target organs were determined using near-infrared (NIR) spectroscopy technique. Moreover, the cellular permeation of the prepared formulations through normal prostate epithelial cells was assessed and compared to pure FSD. The developed micro- and nano-particles were of 930 and 645 nm, respectively. Plasma maximum drug levels (C_max) and overall exposure (AUC) of both formulations were not significantly higher than unformulated drug. However, micronized FSD achieved significant higher concentration within the target tissue (prostate) within the current study compared to pure drug and nano-sized formulation as well. Yet, this is explained by the higher sequestration ability of spleen tissue to the nano-sized formula compared to micro-sized FSD. At the cellular level, permeation of nano-sized FSD through prostate epithelial cells was superior to the unformulated FSD as well as the micro-sized drug formulation. FSD particle size reduction significantly influences its cellular permeation and to a lesser extend affect its systemic pharmacokinetics and tissue distribution after oral administration.

Long-Term Prophylaxis and Pharmacokinetic Evaluation of Intramuscular Nano- and Microparticle Decoquinate in Mice Infected with P. berghei Sporozoites

Decoquinate nanoparticle and microparticle suspended in an oily vehicle to retard drug release are evaluated for long-term malaria prophylaxis. Pharmacokinetic studies in normal animals and antimalarial efficacy in liver stage malaria mice were conducted at various single intramuscular-decoquinate doses for 2, 4, 6, or 8 weeks prior to infection with P. berghei sporozoites. The liver stage efficacy evaluation was monitored by using an in vivo imaging system. Full causal prophylaxis was shown in mice with a single intramuscular dose at 120 mg/kg of nanoparticle decoquinate (0.43 μm) for 2-3 weeks and with microparticle decoquinate (8.31 μm) injected 8 weeks earlier than inoculation. The time above MIC of 1,375 hr observed with the microparticle formulation provided a 2.2-fold longer drug exposure than with the nanoparticle formulation (624 hr). The prophylactic effect of the microparticle formulation observed in mice was shown to be 3-4 times longer than the nanoparticle decoquinate formulation.

Nanoparticle formulations of decoquinate increase antimalarial efficacy against liver stage Plasmodium infections in mice

Decoquinate has potent activity against both Plasmodium hepatic development and red cell replication when tested in vitro. Decoquinate, however, is practically insoluble in water. To achieve its maximal in vivo efficacy, we generated nanoparticle formulations of decoquinate with a mean particle size less than 400 nm. Three separate preparations at doses of decoquinate 0.5-5 mg/kg were examined in mice infected with Plasmodium berghei. Oral administration of nanoparticle decoquinate at a dose of 1.25 mg/kg effectively inhibited the liver-stage parasite growth and provided complete causal prophylactic protection. This efficacy is 15 fold greater than that observed for microparticle decoquinate, which requires minimal dose of 20 mg/kg for the same inhibitory effect. Further in vitro studies utilizing dose-response assays revealed that decoquinate nanoformulation was substantially more potent than decoquinate microsuspension in killing both liver and blood stage malarial parasites, proving its potential for therapeutic development.

FROM THE CLINICAL EDITOR

In this study, a nanoparticle formulation of decoquinate is shown to have superior bioavailability and efficacy in a mouse model of malaria, paving the way to the development of novel, potentially less toxic and more effective therapeutics to combat a disease that still has an enormous impact on a global scale despite the available partially effective therapies.