Solubility and dissolution rate enhancement of lumefantrine using hot melt extrusion technology with physicochemical characterisation

Electromagnetic drop-on-demand (DoD) technology as an innovative platform for amorphous solid dispersion production

Production of amorphous solid dispersions (ASDs) is an effective strategy to promote the solubility and bioavailability of poorly water soluble medicinal substances. In general, ASD is manufactured using a variety of classic and modern techniques, most of which rely on either melting or solvent evaporation. This proof-of-concept study is the first ever to introduce electromagnetic drop-on-demand (DoD) technique as an alternative solvent evaporation-based method for producing ASDs. Herein 3D printing of ASDs for three drug-polymer combinations (efavirenz-Eudragit L100-55, lumefantrine-hydroxypropyl methylcellulose acetate succinate, and favipiravir-polyacrylic acid) was investigated to ascertain the reliability of this technique. Polarized light microscopy, differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), and Fourier Transform  Infrared (FTIR) spectroscopy results supported the formation of ASDs for the three drugs by means of DoD 3D printing, which significantly increases the equilibrium solubility of efavirenz from 0.03 ± 0.04 µg/ml to 21.18 ± 4.20 µg/ml, and the equilibrium solubility of lumefantrine from 1.26 ± 1.60 µg/ml to 20.21 ± 6.91 µg/ml. Overall, the reported findings show how this new electromagnetic DoD technology can have a potential to become a cutting-edge 3D printing solvent-evaporation technique for on-demand and continuous manufacturing of ASDs for a variety of drugs.

Current Trends on Solid Dispersions: Past, Present, and Future

Solid dispersions have achieved significant interest as an effective means of enhancing the dissolution rate and thus the bioavailability of a range of weakly water-soluble drugs. Solid dispersions of weakly water-soluble drugs with water-soluble carriers have lowered the frequency of these problems and improved dissolution. Solid dispersion is a solubilization technology emphasizing mainly on, drug-polymer two-component systems in which drug dispersion and its stabilization is the key to formulation development. Therefore, this technology is recognized as an exceptionally useful means of improving the dissolution properties of poorly water-soluble drugs and in the latest years, a big deal of understanding has been accumulated about solid dispersion, however, their commercial application is limited. In this review article, emphasis is placed on solubility, BCS classification, and carriers. Moreover, this article presents the diverse preparation techniques for solid dispersion and gathers some of the recent technological transfers. The different types of solid dispersions based on the carrier used and molecular arrangement were underlined. Additionally, it summarizes the mechanisms, the methods of preparing solid dispersions, and the marketed drugs that are available using solid dispersion approaches.

Continuous Manufacturing and Molecular Modeling of Pharmaceutical Amorphous Solid Dispersions

Amorphous solid dispersions enhance solubility and oral bioavailability of poorly water-soluble drugs. The escalating number of drugs with poor aqueous solubility, poor dissolution, and poor oral bioavailability is an unresolved problem that requires adequate interventions. This review article highlights recent solubility and bioavailability enhancement advances using amorphous solid dispersions (ASDs). The review also highlights the mechanism of enhanced dissolution and the challenges faced by ASD-based products, such as stability and scale-up. The role of process analytical technology (PAT) supporting continuous manufacturing is highlighted. Accurately predicting interactions between the drug and polymeric carrier requires long experimental screening methods, and this is a space where computational tools hold significant potential. Recent advancements in data science, computational tools, and easy access to high-end computation power are set to accelerate ASD-based research. Hence, particular emphasis has been given to molecular modeling techniques that can address some of the unsolved questions related to ASDs. With the advancement in PAT tools and artificial intelligence, there is an increasing interest in the continuous manufacturing of pharmaceuticals. ASDs are a suitable option for continuous manufacturing, as production of a drug product from an ASD by direct compression is a reality, where the addition of multiple excipients is easy to avoid. Significant attention is necessary for ongoing clinical studies based on ASDs, which is paving the way for the approval of many new ASDs and their introduction into the market.

Development and Characterization of Eudragit® EPO-Based Solid Dispersion of Rosuvastatin Calcium to Foresee the Impact on Solubility, Dissolution and Antihyperlipidemic Activity

Poor solubility is the major challenge involved in the formulation development of new chemical entities (NCEs), as more than 40% of NCEs are practically insoluble in water. Solid dispersion (SD) is a promising technology for improving dissolution and, thereby, the bioavailability of poorly soluble drugs. This study investigates the influence of a pH-sensitive acrylate polymer, EPO, on the physicochemical properties of rosuvastatin calcium, an antihyperlipidemic drug. In silico docking was conducted with numerous polymers to predict drug polymer miscibility. The screened-out polymer was used to fabricate the binary SD of RoC in variable ratios using the co-grinding and solvent evaporation methods. The prepared formulations were assessed for physiochemical parameters such as saturation solubility, drug content and in vitro drug release. The optimized formulations were further ruled out using solid-state characterization (FTIR, DSC, XRD and SEM) and in vitro cytotoxicity. The results revealed that all SDs profoundly increased solubility as well as drug release. However, the formulation RSE-2, with a remarkable 71.88-fold increase in solubility, presented 92% of drug release in the initial 5 min. The molecular interaction studied using FTIR, XRD, DSC and SEM analysis evidenced the improvement of in vitro dissolution. The enhancement in solubility of RoC may be important for the modulation of the dyslipidemia response. Therefore, pharmacodynamic activity was conducted for optimized formulations. Our findings suggested an ameliorative effect of RSE-2 in dyslipidemia and its associated complications. Moreover, RSE-2 exhibited nonexistence of cytotoxicity against human liver cell lines. Convincingly, this study demonstrates that SD of RoC can be successfully fabricated by EPO, and have all the characteristics that are favourable for superior dissolution and better therapeutic response to the drug.

The effects of cis and trans butenedioic acid on the physicochemical behavior of lumefantrine

A study of the differences in the effects of cis (maleic acid) and trans (fumaric acid) isomers of butenedioic acid on the crystallinity, amorphous nature, and pharmaceutical behaviour of the antimalarial drug lumefantrine is provided.

Improved biopharmaceutical attributes of lumefantrine using choline mimicking drug delivery system: preclinical investigation on NK-65 P.berghei murine model

BACKGROUND

Lumefantrine (LMF) is first-line antimalarial drug, possesses activity against almost all human malarial parasites, but the in vivo activity of this molecule gets thwarted due to its low and inconsistent oral bioavailability (i.e. 4-12%) owing to poor biopharmaceutical attributes.

METHODS

Lumefantrine phospholipid complex (LMF-PC) was prepared by rota-evaporation method following job's plot technique for the selection of apt stoichiometric ratios. Docking studies were carried out to determine the possible interaction(s) of LMF with phosphatidylcholine analogue. Comparative in vitro physiochemical, solid-state characterization, MTT assay, dose-response on P. falciparum, in vivo efficacy studies including pharmacokinetic and chemosuppression on NK-65 P. berghei infected mice were carried out.

RESULTS

Aqueous solubility was distinctly improved (i.e. 345 times) with phospholipid complex of LMF. Cytotoxicity studies on Hela and fibroblast cell lines demonstrated safety of LMF-PC with selectivity indices of 4395 and 5139, respectively. IC₅₀ value was reduced almost 2.5 folds. Significant enhancement in C_max (3.3-folds) and AUC (2.7-folds) of rat plasma levels indicated notable pharmacokinetic superiority of LMF-PC over LMF suspension. Differential leukocytic count and cytokine assay delineated plausible immunoregulatory role of LMF-PC with nearly 98% chemosuppression and over 30 days of post-survival.

CONCLUSION

Superior antimalarial efficacy and survival time with full recovery of infected mice revealed through histopathological studies.

Co-precipitates of lumefantrine-Eudragit E PO for dissolution improvement

OBJECTIVES

Lumefantrine, an antimalarial drug, is having poor solubility and variable bioavailability. This work is aimed to prepare and evaluate co-precipitate of lumefantrine-Eudragit E PO to improve its dissolution by anti-solvent precipitation.

MATERIAL AND METHODS

The anti-solvent precipitation technique was used to prepare co-precipitate of lumefantrine-Eudragit E PO at different ratios and based on their solubility; the optimized ratio (1:0.5) was further evaluated for solid state characterization, dissolution and compared with lumefantrine and pure precipitated lumefantrine.

RESULTS

The optimized ratio of co-precipitate (1:0.5) was further evaluated which showed a substantial rise in drug solubility of lumefantrine. SEM photographs indicated dispersion of drug in polymer matrix however, no interaction was observed in FTIR studies. Their DSC and XRPD data revealed the conversion of lumefantrine to its amorphous form. Further, a significant improvement in the rate of dissolution was demonstrated by co-precipitate as compare to pure drug or solely precipitated drug. This may be attributed to the partial conversion of lumefantrine in amorphous form and solubilizing capacity of Eudragit E PO.

CONCLUSION

Thus, co-precipitate of lumefantrine-Eudragit E PO was found to be useful in dissolution improvement and can be further studied for stabilization of co-precipitates.

Molecular Simulation and Statistical Learning Methods toward Predicting Drug-Polymer Amorphous Solid Dispersion Miscibility, Stability, and Formulation Design

Amorphous solid dispersions (ASDs) have emerged as widespread formulations for drug delivery of poorly soluble active pharmaceutical ingredients (APIs). Predicting the API solubility with various carriers in the API-carrier mixture and the principal API-carrier non-bonding interactions are critical factors for rational drug development and formulation decisions. Experimental determination of these interactions, solubility, and dissolution mechanisms is time-consuming, costly, and reliant on trial and error. To that end, molecular modeling has been applied to simulate ASD properties and mechanisms. Quantum mechanical methods elucidate the strength of API-carrier non-bonding interactions, while molecular dynamics simulations model and predict ASD physical stability, solubility, and dissolution mechanisms. Statistical learning models have been recently applied to the prediction of a variety of drug formulation properties and show immense potential for continued application in the understanding and prediction of ASD solubility. Continued theoretical progress and computational applications will accelerate lead compound development before clinical trials. This article reviews in silico research for the rational formulation design of low-solubility drugs. Pertinent theoretical groundwork is presented, modeling applications and limitations are discussed, and the prospective clinical benefits of accelerated ASD formulation are envisioned.

Application of the Box-Behnken design for the production of soluble curcumin: Skimmed milk powder inclusion complex for improving the treatment of colorectal cancer

The main objective of this study was to develop a soluble product of the practically insoluble curcumin (CMN) to treat colorectal cancer more effectively than with pure CMN. To improve the solubility of CMN, various hydrophilic carriers of skimmed milk powder (SMP), polyvinylpyrrolidone (PVP), and mannitol (MNT) were utilized to prepare solid dispersion (SD) binary complexes. The prepared complexes were characterized in terms of their aqueous solubility and in vitro drug release and analyzed by Fourier transform infrared spectrophotometry, powder X-ray diffractometry, scanning electron microscopy, dynamic light scattering, and the novel dyeing test. Based on this characterization, the best SD complex was optimized using the Box-Behnken design (RSM-BBD). These results showed that the solubility of CMN was greatly improved in combination with SMP. The SD of CMN with SMP produced significantly improved solubility (0.646 ± 0.024 mg/ml) and dissolution (54.94 ± 3.21% at 5 min). Further, solid-state characterization revealed that the complex exhibited intermolecular inclusion of the drug and carrier. Also, the complex did not undergo any chemical modification owing to its amorphous form, and the novel dye test showed better coloring impact, indicating the solubility of CMN. The in vitro cytotoxicity of the complex showed that 50% inhibition (IC50) of SW480 and Caco-2 cells was achieved at a considerably lower concentration than that of pure CMN. Flow cytometry analysis confirmed that the cell cycle arrest was at G2/M phase (43.26% and 65.14%), and DNA fragmentation analysis investigation confirmed that the complex induced more DNA damage during apoptosis.

Therapeutic Applications of Solid Dispersions for Drugs and New Molecules: In Vitro and In Vivo Activities

This review aims to provide an overview of studies that address the use, in therapeutic applications, of solid dispersions (SDs) with biological activities in vitro and/or in vivo mainly made up of polymeric matrices, as well as to evaluate the bioactive activity of their constituents. This bibliographic survey shows that the development of solid dispersions provides benefits in the physicochemical properties of bioactive compounds, which lead to an increase in their biological potential. However, despite the reports found on solid dispersions, there is still a need for biological assay-based studies, mainly in vivo, to assist in the investigation and to devise new applications. Therefore, studies based on such an approach are of great importance to enhance and extend the use of solid dispersions in the most diverse therapeutic applications.

Bioavailability Enhancement of Olmesartan Medoxomil Using Hot-Melt Extrusion: In-Silico, In-Vitro, and In-Vivo Evaluation

Olmesartan medoxomil (OLM) an antihypertensive molecule with poor solubility and poor bioavailability (26% when taken orally) was selected as a model drug. Herein, rationale development of amorphous solid dispersion with hot-melt extrusion of poorly bioavailable OLM was carried out with the aid of quality by design (QbD), in-silico, in-vitro, and in-vivo evaluations. Polymer selection commenced with the selection of thermoplastic water-soluble polymers with the compatible processing temperature window as per the thermal behavior of OLM. Molecular dynamics (MD) simulations as well assisted in the selection of a carrier. Promising dissolution enhancement was observed with the help of Kollidon VA-64 (VA-64) as a carrier. Optimization of the formulation was executed using the QbD approach with design of experiment as a statistical optimization tool. Interactions between VA-64 and OLM on the atomic level were studied with the help of atomistic MD simulations. Characterization of the optimized extrudates were carried out with scanning electron microscopy, atomic force microscopy, differential scanning calorimetry, thermogravimetric analysis, Fourier transforms infrared spectroscopy, powder X-ray diffraction, in-vitro dissolution study, and in-vivo pharmacokinetic studies. Molecular-level mixing of OLM with VA-64 resulted into glass solution formation which rapidly dissolves (28 times in-vitro dissolution enhancement) in GI tract fluids and instantly gets absorbed into blood circulation. In-vivo pharmacokinetic studies performed in Sprague-Dawley rats reflected superior bioavailability (201.60%) with a significant increase in the C_max with short T_max through amorphization of OLM. The in-silico results were in agreement with the observed results of in-vitro dissolution studies and in-vivo pharmacokinetic study.

Multiple approaches for achieving drug solubility: an in silico perspective

Discovering new therapeutically active molecules is the ultimate destination in pharmaceutical research and development. Most drugs discovered are lipophilic and, hence, exhibit poor aqueous solubility, resulting in low bioavailability. Thus, there is a need to use various solubility enhancement techniques. Computational approaches enable the analysis of drug-carrier interactions or the numerous conformational changes in the carrier matrix that might establish an appropriate balance between cohesive and adhesive stability in a formulation. In this review, we discuss research approaches that provided molecular insight into drugs and their modifiers to unravel their solubility, stability, and bioavailability.

22 factorial design-based biocompatible microneedle arrays containing artemether co-loaded with lumefantrine nanoparticles for transepidermal delivery

The present study was intended to enhance the permeation of artemether and lumefantrine by encapsulating in dissolvable microneedle arrays for extended action. Lumefantrine-nanoparticles were synthesized using chitosan mediated gelation and optimized by 2² factorial designs. The particle size, zeta potential and % entrapment efficiency of the optimized nanoparticles F5 were 105 ± 3.64 nm, 24.4 ± 0.54 mV and 83.94 ± 1.71%, respectively. The nanoparticles showed a controlled-release of 79.15 ± 2.45% for lumefantrine after 24 h and stability for 6 months. A combination of biocompatible polymers (PVA and PVP K - 12) was used to develop dissolvable microneedle of artemether co-loaded lumefantrine nanoparticles. The SEM and TEM analysis confirmed the needle-shaped morphology with a size of 672 ± 0.99 μm. The in-vitro release of microneedle showed biphasic release pattern for both artemether and lumefantrine, with an initial burst followed by controlled-release profile. The ex-vivo study of optimized formulation showed 70.94 ± 2.45% and 65.87 ± 1.94% permeation for artemether and lumefantrine, respectively, after 24 h. Thus, microneedle-based delivery provides an alternative to painful intravenous administration and a promising approach to increase the penetration of drugs across the skin barrier. Graphical abstract Fabrication of microneedle arrays of artemether co-loaded with lumefantrine nanoparticles.

Electrospun amorphous solid dispersions of poorly water-soluble drugs: A review

The development of oral dosage forms for poorly water-soluble active pharmaceutical ingredients (APIs) is a persistent challenge. A range of methods has been explored to address this issue, and amorphous solid dispersions (ASDs) have received increasing attention. ASDs are typically prepared by starting with a liquid precursor (a solution or melt) and applying energy for solidification. Many techniques can be used, with the emergence of electrospinning as a potent option in recent years. This method uses electrical energy to induce changes from liquid to solid. Through the direct applications of electrical energy, electrospinning can generate nanofiber-based ASDs from drug-loaded solutions, melts and melt-solutions. The technique can also be combined with other approaches using the application of mechanical, thermal or other energy sources. Electrospinning has numerous advantages over other approaches to produce ASDs. These advantages include extremely rapid drying speeds, ease of implentation, compatibility with a wide range of active ingredients (including those which are thermally labile), and the generation of products with large surface areas and high porosity. Furthermore, this technique exhibits the potential to create so-called 'fifth-generation' ASDs with nanostructured architectures, such as core/shell or Janus systems and their combinations. These advanced systems can improve dissolution behaviour and provide programmable drug release profiles. Additionally, the fiber components and their spatial distributions can be precisely controlled. Electrospun fiber-based ASDs can maintain an incorporated active ingredient in the amorphous physical form for prolonged periods of time because of their homogeneous drug distribution within the polymer matrix (typically they comprise solid solutions), and ability to inhibit molecular motion. These ASDs can be utilised to generate oral dosage forms for poorly water-soluble drugs, resulting in linear or multiple-phase release of one or more APIs. Electrospun ASDs can also be exploited as templates for manipulating molecular self-assembly, offering a bridge between ASDs and other types of dosage forms. This review addresses the development, advantages and pharmaceutical applications of electrospinning for producing polymeric ASDs. Material preparation and analysis procedures are considered. The mechanisms through which performance has been improved are also discussed.

Investigating the molecular dissolution process of binary solid dispersions by molecular dynamics simulations

Dissolution molecular mechanism of solid dispersions still remains unclear despite thousands of reports about this technique. The aim of current research was to investigate the molecular dissolution mechanism of solid dispersions by molecular dynamics simulations. The formation of ibuprofen/polymer solid dispersions was modeled by the simulated annealing method. After that, the models of solid dispersions were immersed into the water box with 25–30 Å thicknesses and 50–100 ns MD simulations were performed to all systems. Simulation results showed various dissolution behaviors in different particle sizes and various polymers of solid dispersions. Small-sized particles of solid dispersions dissolved quickly in the water, while the large particles of PEG or PVP-containing solid dispersions gradually swelled in the dissolution process and drug molecules may aggregate together. In the dissolution process, the carboxylic groups of ibuprofen molecules turned its direction from polymer molecules to external water box and then the drug molecules left the polymer coils. At the same time, polymer coils gradually relaxed and became free polymer chains in the solution. In addition, solid dispersion with poloxamer could prevent the precipitate of drug molecules in the dissolution process, which is different from those of PEG or PVP-containing systems. This research provided us clear images of dissolution process of solid dispersions at the molecular level.

Using Supercritical Fluid Technology (SFT) in Preparation of Tacrolimus Solid Dispersions

Tacrolimus is an immunosuppressant agent that suffers from poor and variable bioavailability. This can be related to limited solubility and dissolution. The main objective of this study is to use SFT to prepare solid dispersions of tacrolimus in order to enhance its dissolution. SFT was selected since it offers several advantages over conventional techniques such as efficiency and stability. Several solid dispersions of tacrolimus were prepared using SFT to enhance its dissolution. The selected polymers included soluplus, PVP, HPMC, and porous chitosan. TPGS was used as a surfactant additive with chitosan, HPMC, and PVP. Soluplus dispersions were used to study the effect of processing parameters (time, temperature, and pressure) on loading efficiency (LE) and dissolution of the preparation. Physicochemical characterization was performed using DSC, X-ray diffraction, FTIR analysis, SEM, and in vitro drug release. Stability testing was evaluated after 3 months for selected dispersions. Significant improvement for the release profile was achieved for the prepared dispersions. Better release achieved in the soluplus dispersions which reached maximum cumulative release equal to 98.76% after 24 h. Drug precipitated in its amorphous form in all prepared dispersions except those prepared from chitosan. All dispersions were physically stable except for PVP preparations that contained TPGS which started to re-crystallize after one month. Prepared dispersions were proved to be affected by supercritical processing parameters. In conclusion, SFT was successfully used to prepare dispersions of tacrolimus that exhibited higher dissolution than raw drug. Dissolution rate and stability are affected by the type of the polymer.

Hot melt extrusion based solid solution approach: Exploring polymer comparison, physicochemical characterization and in-vivo evaluation

The objective of this study was to develop solid solution (SSL) using hot-melt extrusion as a continuous manufacturing method. Powder blends of artesunate (ARS) a water insoluble drug with either Soluplus (SOL) or Kollidon VA64 (VA64) and additives in the form of surfactants or plasticizers were extruded to manufacture extrudes. The incorporation of surfactant or plasticizers facilitates smooth extrusion processing of the drug-excipient blend which directly reduced the residence time to form extrudes and works as parameter to control flow of the drug-excipients melt inside the extruder barrel. Differential scanning calorimetry (DSC) and X-ray diffraction (TXRD) analysis revealed the existence of the drug within the extrudes in amorphous state. Scanning electron microscopy (SEM), Raman spectroscopy (RS), Raman imaging (RI) and Atomic force microscopy (AFM) analytical characterization were carry out on the SSL formulations showed a homogeneous drug distribution within the extrudes. (2)D NMR and (1)H NMR studies were undertaken to reveal the possible drug-excipient interactions. The SSL produced via continuous HME processing showed significantly faster release of ARS compared to the pure drug substance. It is observed that F1 SSL (soluplus based) have 66.44 times higher AUC(0-72) and 16.60 times higher Cmax than pure ARS. Also K1 SSL (Kollidon VA64 based) have 62.20 times higher AUC(0-72) and 13.40 times higher Cmax than pure ARS.

Development of hot melt co-formulated antimalarial solid dispersion system in fixed dose form (ARLUMELT): Evaluating amorphous state and in vivo performance

The aim of this study was to investigate the industrial feasibility of developing a co-formulated solid dispersion (SD) containing two antimalarial drugs artemether (ARTM) and lumefantrine (LUMF). Soluplus(®) (polyethyleneglycol-polyvinyl caprolactam-polyvinyl acetate grafted copolymer) was used as primary carrier matrices via hot-melt extrusion processing to improve solubility profile and the oral bioavailability of the combination. Based on the preliminary screening, the optimized quantities of PEG 400, Lutrol F127 and Lutrol F68 were incorporated as surfactant with soluplus in different ratios to improve extrudability, increase wettability and the melt viscosity of the HME process. Soluplus(®) was proved to successfully stabilize both the drugs inside its polymeric network during extrusion via forming a stable solid dispersion. Physicochemical properties of the APIs and the SDs characterized by thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), MDSC, FTIR spectroscopy and X-ray diffractometry (XRD) revealed the amorphous existence of the drug in all SDs developed. Molecular level morphology of solid dispersion characterized by using advanced physicochemical characterization techniques such as Raman spectroscopy, atomic force microscopy (AFM) and 2D NMR showed the transformation of the crystalline drugs to its stable amorphous state. All manufactured SDs retained their amorphicity even after a stability study conducted in accelerated condition over 6 months. The solubility and in vitro dissolution performance of both drugs in SD formulations was improved significantly when compared with pure drugs and marketed product while the in vivo studies revealed the same.The pharmacokinetic studies in rats revealed that the SD (AL1) shows a 44.12-65.24 folds increase in the AUC(0-72) and 42.87-172.61 folds increase in Cmax compared to that of pure drugs and a better bioavailability than that of commercial product.

Drug-polymer interactions at water-crystal interfaces and implications for crystallization inhibition: molecular dynamics simulations of amphiphilic block copolymer interactions with tolazamide crystals

A diblock copolymer, poly(ethylene glycol)-block-poly(lactic acid) (PEG-b-PLA), modulates the crystal growth of tolazamide (TLZ), resulting in a crystal morphology change from needles to plates in aqueous media. To understand this crystal surface drug-polymer interaction, we conducted molecular dynamics simulations on crystal surfaces of TLZ in water containing PEG-b-PLA. A 130-ns simulation of the polymer in a large water box was run before initiating 50 ns simulations with each of the crystal surfaces. The simulations demonstrated differentiated drug-polymer interactions that are consistent with experimental studies. Interaction of PEG-b-PLA with the (001) face occurred more rapidly (≤10 ns) and strongly (total interaction energy of -121.1 kJ/mol/monomer) than that with the (010) face (∼35 ns, -85.4 kJ/mol/monomer). There was little interaction with the (100) face. Hydrophobic and van der Waals (VDW) interactions were the dominant forces, accounting for more than 90% of total interaction energies. It suggests that polymers capable of forming strong hydrophobic and VDW interactions might be more effective in inhibiting crystallization of poorly water-soluble and hydrophobic drugs in aqueous media (such as gastrointestinal fluid) than those with hydrogen-bonding capacities. Such in-depth analysis and understanding facilitate the rational selection of polymers in designing supersaturation-based enabling formulations.

Hot melt extruded amorphous solid dispersion of posaconazole with improved bioavailability: investigating drug-polymer miscibility with advanced characterisation

Invasive antifungal infections are reasons for morbidity and mortality in immunogenic patients worldwide. Posaconazole is a most promising antifungal agent against all types of invasive infections with high % of cure rate. The marketed suspension formulation has low bioavailability and is needed to be taken with food. In this paper, PCZ hot melt extruded amorphous solid dispersion (SD) with immediate release and improved bioavailability was prepared using Soluplus (Sol) as primary carrier for solubilization. Surfactants such as PEG 400, Lutrol F27, Lutrol F68, and TPGS are also used in combination with Soluplus to improve the physicochemical performance of the formulation when it comes in contact with GI (gastrointestinal) fluid. Drug-polymer miscibility of SD was investigated using advanced techniques. In the in vivo study, the AUC_(0–72) and C_max of PCZ/Soluplus were 11.5 and 11.74 time higher than those of pure PCZ. The formulation of the extrudate SD had an AUC_(0–72) and C_max higher than those with the commercial capsule (Noxafil). Molecular dynamic (MD) simulation studies were carried out using in silico molecular modelling to understand the drug-polymer intermolecular behaviour. The results of this research ensure enhanced dissolution and bioavailability of the solid dispersion of PCZ prepared by HME compared with the PCZ suspension.

Ex vivo anti-malarial drugs sensitivity profile of Plasmodium falciparum field isolates from Burkina Faso five years after the national policy change

BACKGROUND

The recent reports on the decreasing susceptibility of Plasmodium falciparum to artemisinin derivatives along the Thailand and Myanmar border are worrying. Indeed it may spread to India and then Africa, repeating the same pattern observed for chloroquine resistance. Therefore, it is essential to start monitoring P. falciparum sensitivity to artemisinin derivatives and its partner drugs in Africa. Efficacy of AL and ASAQ were tested by carrying out an in vivo drug efficacy test, with an ex vivo study against six anti-malarial drugs nested into it. Results of the latter are reported here.

METHODS

Plasmodium falciparum ex-vivo susceptibility to chloroquine (CQ), quinine (Q), lumefantrine (Lum), monodesethylamodiaquine (MDA), piperaquine (PPQ) and dihydroartemisinin (DHA) was investigated in children (6 months - 15 years) with a parasitaemia of at least ≥4,000/μl. The modified isotopic microtest technique was used. The results of cellular proliferation were analysed using ICEstimator software to determine the 50% inhibitory concentration (IC50) values.

RESULTS

DHA was the most potent among the 6 drugs tested, with IC50 values ranging from 0.8 nM to 0.9 nM (Geometric mean IC50 = 0.8 nM; 95% CI [0.8 - 0.9]). High IC50 values ranged between 0.8 nM to 166.1 nM were reported for lumefantrine (Geometric mean IC50 = 25.1 nM; 95% CI [22.4 - 28.2]). MDA and Q IC50s were significantly higher in CQ-resistant than in CQ-sensitive isolates (P = 0.0001). However, the opposite occurred for Lum and DHA (P < 0.001). No difference was observed for PPQ.

CONCLUSION

Artemisinin derivatives are still very efficacious in Burkina Faso and DHA-PPQ seems a valuable alternative ACT. The high lumefantrine IC50 found in this study is worrying as it may indicate a decreasing efficacy of one of the first-line treatments. This should be further investigated and monitored over time with large in vivo and ex vivo studies that will include also plasma drug measurements.

Investigation of the functional role of P-glycoprotein in limiting the oral bioavailability of lumefantrine

In the quest to explore the reason for the low and variable bioavailability of lumefantrine, we investigated the possible role of P-glycoprotein (P-gp) in lumefantrine intestinal absorption. An in situ single-pass intestinal perfusion study in rats with the P-gp inhibitor verapamil or quinidine and an ATPase assay with human P-gp membranes indicated that lumefantrine is a substrate of P-gp which limits its intestinal absorption. To confirm these findings, an in vivo pharmacokinetic study was performed in rats. The oral administration of verapamil (10 mg/kg of body weight) along with lumefantrine caused a significant increase in its bioavailability with a concomitant decrease in clearance. The increase in bioavailability of lumefantrine could be due to inhibition of P-gp and/or cytochrome P450 3A in the intestine/liver by verapamil. However, in a rat intestinal microsomal stability study, lumefantrine was found to be resistant to oxidative metabolism. Further, an in situ permeation study clearly showed a significant role of P-gp in limiting the oral absorption of lumefantrine. Thus, the increase in lumefantrine bioavailability with verapamil is attributed in part to the P-gp-inhibitory ability of verapamil. In conclusion, lumefantrine is a substrate of P-gp, and active efflux by P-gp across the intestine partly contributed to the low/variable bioavailability of lumefantrine.