Ground Calcium Carbonate as a Low Cost and Biosafety Excipient for Solubility and Dissolution Improvement of Praziquantel

Amorphous Solid Dispersion Formation for Enhanced Release Performance of Racemic and Enantiopure Praziquantel

Praziquantel (PZQ) is the treatment of choice for schistosomiasis, which affects more than 250 million people globally. Commercial tablets contain the crystalline racemic compound (RS-PZQ) which limits drug dissolution and oral bioavailability and can lead to unwanted side effects and poor patient compliance due to the presence of the S-enantiomer. While many approaches have been explored for improving PZQ's dissolution and oral bioavailability, studies focusing on investigating its release from amorphous solid dispersions (ASDs) have been limited. In this work, nucleation induction time experiments were performed to identify suitable polymers for preparing ASDs using RS-PZQ and R-PZQ, the therapeutically active enantiomer. Cellulose-based polymers, hydroxypropyl methylcellulose acetate succinate (HPMCAS, MF grade) and hydroxypropyl methylcellulose (HPMC, E5 LV grade), were the best crystallization inhibitors for RS-PZQ in aqueous media and were selected for ASD preparation using solvent evaporation (SE) and hot-melt extrusion (HME). ASDs prepared experimentally were subjected to X-ray powder diffraction to verify their amorphous nature and a selected number of ASDs were monitored and found to remain physically stable following several months of storage under accelerated-stability testing conditions. SE HPMCAS-MF ASDs of RS-PZQ and R-PZQ showed faster release than HPMC E5 LV ASDs and maintained good performance with an increase in drug loading (DL). HME ASDs of RS-PZQ formulated using HPMCAS-MF exhibited slightly enhanced release compared to that of SE ASDs. SE HPMCAS-MF ASDs showed a maximum release increase of the order of 6 times compared to generic and branded (Biltricide) PZQ tablets. More importantly, SE R-PZQ ASDs with HPMCAS-MF released the drug as effectively as RS-PZQ or better, depending on the DL used. These findings have significant implications for the development of commercial PZQ formulations comprised solely of the R-enantiomer, which can result in mitigation of the biopharmaceutical and compliance issues associated with current commercial tablets.

Exploring the Therapeutic Potential of 5-Fluorouracil-Loaded Calcium Carbonate Nanoparticles Combined with Natural Compound Thymoquinone for Colon Cancer Treatment

Given the need for novel and effective therapies for colon cancer, this study aimed to investigate the effects of 5-fluorouracil-loaded calcium carbonate nanoparticles (5FU-CaCO3np) combined with thymoquinone (TQ) against colon cancer. A shaking incubator and a high-speed homogenizer were used to prepare the optimal 5FU-CaCO3np, with characterizations of physicochemical properties, in vitro drug release profile, and biocompatibility. In vitro experiments and molecular docking were employed to evaluate the therapeutic potential of the combination for colon cancer treatment. Study results revealed that 5FU-CaCO3np with a size of approximately 130 nm was synthesized using the high-speed homogenizer. Its favorable biocompatibility, pH sensitivity, and sustained release properties facilitated reduced toxic side effects of 5-FU on NIH3T3 normal cells and enhanced inhibitory effects on CT26 colon cancer cells. The combination of 5FU-CaCO3np (1.875 μM) and TQ (30 μM) showed significantly superior anti-colon cancer effects to 5FU-CaCO3np alone in terms of cell proliferation and migration inhibition, cell apoptosis induction, and spheroid growth suppression in CT26 cells (p < 0.05), with strong interactions between the drugs and targets (E-cadherin, Bcl-2, PCNA, and MMP-2). These results provide evidence for 5FU-CaCO3np as a novel regimen against colon cancer. Combining 5FU-CaCO3np and TQ may offer a new perspective for colon cancer therapy.

Praziquantel Fifty Years on: A Comprehensive Overview of Its Solid State

This review discusses the entire progress made on the anthelmintic drug praziquantel, focusing on the solid state and, therefore, on anhydrous crystalline polymorphs, amorphous forms, and multicomponent systems (i.e., hydrates, solvates, and cocrystals). Despite having been extensively studied over the last 50 years, new polymorphs and the greater part of their cocrystals have only been identified in the past decade. Progress in crystal engineering science (e.g., the use of mechanochemistry as a solid form screening tool and more strategic structure-based methods), along with the development of analytical techniques, including Synchrotron X-ray analyses, spectroscopy, and microscopy, have furthered the identification of unknown crystal structures of the drug. Also, computational modeling has significantly contributed to the prediction and design of new cocrystals by considering structural conformations and interactions energy. Whilst the insights on praziquantel polymorphs discussed in the present review will give a significant contribution to controlling their formation during manufacturing and drug formulation, the detailed multicomponent forms will help in designing and implementing future praziquantel-based functional materials. The latter will hopefully overcome praziquantel's numerous drawbacks and exploit its potential in the field of neglected tropical diseases.

Vaterite microparticle-loaded methylene blue for photodynamic activity in macrophages infected with Leishmania braziliensis

Calcium carbonate (CaCO3) exhibits a variety of crystalline phases, including the anhydrous crystalline polymorphs calcite, aragonite, and vaterite. Developing porous calcium carbonate microparticles in the vaterite phase for the encapsulation of methylene blue (MB) as a photosensitizer (PS) for use in photodynamic therapy (PDT) was the goal of this investigation. Using an adsorption approach, the PS was integrated into the CaCO3 microparticles. The vaterite microparticles were characterized by scanning electron microscopy (SEM) and steady-state techniques. The trypan blue exclusion method was used to measure the biological activity of macrophages infected with Leishmania braziliensis in vitro. The vaterite microparticles produced are highly porous, non-aggregated, and uniform in size. After encapsulation, the MB-loaded microparticles kept their photophysical characteristics. The carriers that were captured allowed for dye localization inside the cells. The results obtained in this study indicated that the MB-loaded vaterite microparticles show promising photodynamic activity in macrophages infected with Leishmania braziliensis.

Emergence of Power-Law Particle Size Distribution in Microfluidic Calcium Carbonate Precipitation: An Extended Yule Process with a Ripening Effect

Precipitation of calcium carbonate in bulk solutions is well known to result in a bell-shaped or bimodal particle size distribution. However, it is unclear how the distribution behaves if precipitation occurs in a small, confined volume. In this Letter, we conduct microfluidic experiments where sodium carbonate and calcium chloride solutions are continuously injected into a microchannel to precipitate calcium carbonate particles. Results show that, regardless of the variations in reagent concentrations, mixing schemes, flow rates, and precipitation time, sizes of precipitated particles in the channel are power law distributed, with an exponent of 1.4. The data are described by an extended Yule process with the introduction of a ripening term. Since the Yule process is a general mechanism for power law generation, the extended Yule process proposed here provides a general model for systems where growth and ripening simultaneously present.

A New Challenge for the Old Excipient Calcium Carbonate: To Improve the Dissolution Rate of Poorly Soluble Drugs

Calcium carbonate is an excipient traditionally used in solid dosage forms with several functions such as a diluent, a quick dissolution agent, a buffer and an opacifier. Recently, many other challenges have arisen for calcium carbonate and, among them, the possibility of using it as an excipient for improving the dissolution rate of poorly soluble drugs. As a consequence of their poor solubility in biological fluids, many active ingredients suffer from low and erratic bioavailability when administered by the oral route and thus, many formulation strategies and excipients have been proposed to overcome this problem. Among them, calcium carbonate has been proposed as an excipient for improving dissolution rates. Calcium carbonate has many interesting characteristics, in fact it dissolves quickly in gastric fluid, is inexpensive and is safe. It exists in different polymorphic forms and in porous morphology and recently a porous functionalized calcium carbonate has been proposed as a new excipient. This review is the first overview on the use of calcium carbonate as an excipient for improving drug dissolution rates. The drug loading procedure, the physical characterization of the drug/CaCO3 samples and their dissolution profiles will be described. Moreover, the possible mechanisms of dissolution improvement, such as the presence of the drug in amorphous or polymorphic forms, in small crystals, and the effects of CaCO3 dissolution in acidic medium will be discussed. Different polymorphic forms of calcium carbonate and the presence of porosity and functionalization will be analyzed as well and their effects on dissolution rates will be discussed.

Recent trends in praziquantel nanoformulations for helminthiasis treatment

INTRODUCTION

Infections caused by parasitic flatworms impose a considerable worldwide health burden. Recently, World Health Organization launched its roadmap for neglected diseases for the period 2021 to 2030 and oral treatment with praziquantel (PZQ) in tablet form is the main drug therapy for combating these diseases, but its use is limited by many drawbacks, including the high therapeutic dose due to the drug's low solubility and bioavailability. Among the strategies to improve PZQ performance, the use of drug nanocarriers has been cited as an interesting approach to overcome these pharmacological issues.

AREAS COVERED

This review focuses on the various types of nanomaterials (polymeric, lipidic, inorganic nanoparticles, and nanocrystals) which have been recently used to improve PZQ therapy. In addition, recent advances in PZQ nanoformulations, developed to overcome the barriers of the conventional drug are described.

EXPERT OPINION

Considering the poor rate of discovery in the anthelmintic segment observed in recent decades, the effective management of existing drugs has become essential. The application of new strategies based on nanotechnology can extend the useful life of PZQ in new and more effective formulations. Pharmaceutical nanotechnology can solve the pharmacokinetic challenges characteristic of PZQ and improve its solubility and bioavailability.

Combinations of Freeze-Dried Amorphous Vardenafil Hydrochloride with Saccharides as a Way to Enhance Dissolution Rate and Permeability

To improve physicochemical properties of vardenafil hydrochloride (VAR), its amorphous form and combinations with excipients-hydroxypropyl methylcellulose (HPMC) and β-cyclodextrin (β-CD)-were prepared. The impact of the modification on physicochemical properties was estimated by comparing amorphous mixtures of VAR to their crystalline form. The amorphous form of VAR was obtained as a result of the freeze-drying process. Confirmation of the identity of the amorphous dispersion of VAR was obtained through the use of comprehensive analysis techniques-X-ray powder diffraction (PXRD) and differential scanning calorimetry (DSC), supported by FT-IR (Fourier-transform infrared spectroscopy) coupled with density functional theory (DFT) calculations. The amorphous mixtures of VAR increased its apparent solubility compared to the crystalline form. Moreover, a nearly 1.3-fold increase of amorphous VAR permeability through membranes simulating gastrointestinal epithelium as a consequence of the changes of apparent solubility (P_{app crystalline VAR} = 6.83 × 10^-6 cm/s vs. P_{app amorphous VAR} = 8.75 × 10^-6 cm/s) was observed, especially for its combinations with β-CD in the ratio of 1:5-more than 1.5-fold increase (P_{app amorphous VAR} = 8.75 × 10^-6 cm/s vs. P_{app amorphous VAR:β-CD 1:5} = 13.43 × 10^-6 cm/s). The stability of the amorphous VAR was confirmed for 7 months. The HPMC and β-CD are effective modifiers of its apparent solubility and permeation through membranes simulating gastrointestinal epithelium, suggesting a possibility of a stronger pharmacological effect.

Improving the Solubility of Aripiprazole by Multicomponent Crystallization

Aripiprazole (ARI) is a third-generation antipsychotic with few side effects but a poor solubility. Salt formation, as one common form of multicomponent crystals, is an effective strategy to improve pharmacokinetic profiles. In this work, a new ARI salt with adipic acid (ADI) and its acetone hemisolvate were obtained successfully, along with a known ARI salt with salicylic acid (SAL). Their comprehensive characterizations were conducted using X-ray diffraction and differential scanning calorimetry. The crystal structures of the ARI-ADI salt acetone hemisolvate and ARI-SAL salt were elucidated by single-crystal X-ray diffraction for the first time, demonstrating the proton transfer from a carboxyl group of acid to ARI piperazine. Theoretical calculations were also performed on weak interactions. Moreover, comparative studies on pharmaceutical properties, including powder hygroscopicity, stability, solubility, and the intrinsic dissolution rate, were carried out. The results indicated that the solubility and intrinsic dissolution rate of the ARI-ADI salt and its acetone hemisolvate significantly improved, clearly outperforming that of the ARI-SAL salt and the untreated ARI. The study presented one potential alternative salt of aripiprazole and provided a potential strategy to increase the solubility of poorly water-soluble drugs.

Pyrolysis synergy of municipal solid waste (MSW): A review

The synergistic pyrolysis of municipal solid waste (MSW) were recently explored. This review aims to provide an overview on the synergistic pyrolysis studies of MSW, focusing on the synergy occurred during co-pyrolysis of different constituents of MSW. The interactions of intermediates released during pyrolysis can shift end product distributions, accelerate pyrolysis rates, and preferred production of specific compounds, which were categorized into four basic types with discussions. The pyrolysis synergy is proposed to be the key for success of pyrolytic practice of MSW that can handle the waste with maximal resource recovery and minimal carbon emission.

Use of calcium carbonate as an excipient for release of poorly water soluble drugs: The case of carbamazepine

Carbamazepine (CBZ) is a poorly water soluble drug owing to the Biopharmaceutic Classification System (BCS) class II. It is characterized by a variable bioavailability and by the presence of different polymorphs. In this paper the effects of CaCO₃ on the physicochemical properties of CBZ and its solubility and release were evaluated. CaCO₃ is a naturally non-toxic biomineral and was chosen because it is a safe, cheap and eco-friendly excipient able to dissolve in an acidic environment. Composites with different CBZ loadings were prepared by ball milling and antisolvent method. The composites were characterized by X-ray powder diffraction, differential scanning calorimetry analysis and attenuated total reflectance FT-IR which revealed that both the presence of CaCO₃ and the preparation procedure affect the polymorphic form crystallinity and intermolecular interactions among the drug molecules. Scanning electron microscopy showed that small drug crystals with different crystalline forms were deposited on the surface of the CaCO₃ particles. Solubility and dissolution tests showed an increase in the apparent solubility of CBZ and improved drug release. These results demonstrated that CaCO₃ affected the drug release properties likely due to its pH-sensitive characteristics.

Praziquantel-Clays as Accelerated Release Systems to Enhance the Low Solubility of the Drug

Praziquantel is an antiparasitic drug indicated for the treatment of the schistosomiasis disease. This drug has very low aqueous solubility, requiring high oral doses for its administration which gives rise to side effects, therapeutic noncompliance and the appearance of resistant forms of the parasite. Clay minerals, like sepiolite and montmorillonite, are innocuous, non-toxic, biocompatible and low-cost excipients. Additionally, clays have high adsorbent properties that allow them to encapsulate drugs in nanometric spaces present in the channels in the case of the sepiolite or between the layers in the case of the montmorillonite. The interactions between the drug and clay minerals are studied experimentally with the strategy for preparing interactions products in organic solvents (ethanol, acetonitrile and dichloromethane) so that the interaction will be more effective and will be enhanced the aqueous solubility of praziquantel. The results showed that in the interaction products, the drug interacted with both clay minerals, which produced the loss of the crystallinity of the drug demonstrated by different techniques. This led to a significant increase in the dissolution rate of the praziquantel in all the interaction products in the simulated gastrointestinal tract media, except for the praziquantel–montmorillonite product prepared in dichloromethane that presented a controlled release in acid medium. Moreover, in vitro cytotoxicity and cell cycle studies were performed in the interaction products prepared with ethanol. The interaction product with sepiolite was biocompatible with the HTC116 line cells, and it did not produce alterations in the cell cycle. However, interaction products with montmorillonite did not produce cell death, but they showed affectation and damage of cells in the cell cycle study at the highest concentration tested (20–100 µM). Therefore, the different organic solvents used are adequate for the improvement of the biopharmaceutical profile of praziquantel. Drug–clay interaction products, specifically with sepiolite, showed very promising results in which new accelerated oral release systems of the praziquantel were obtained.

Antifungal and Antiparasitic Drug Delivery

Fungal and parasitic diseases affect more than a billion people across the globe, one-sixth of the world’s population, mostly located in developing countries. The lack of effective and safer treatments combined with a deficient diagnosis lead to serious chronic illness or even death. There is a mismatch between the rate of drug resistance and the development of new medicines. Formulation of antifungal and antiparasitic drugs adapted to different administration routes is challenging, bearing in mind their poor water solubility, which limits their bioavailability and efficacy. Hence, there is an unmet clinical need to develop vaccines and novel formulations and drug delivery strategies that can improve the bioavailability and therapeutic effect by enhancing their dissolution, increasing their chemical potency, stabilising the drug and targeting high concentration of drug to the infection sites. This Editorial regards the ten research contributions presented in the Special Issue “Antifungal and Antiparasitic Drug Delivery”.

Calcium carbonate nanowires: greener biosynthesis and their leishmanicidal activity

The synthesis of inorganic rod shape nanostructures is important in chromatography, dentistry, and medical applications such as bone implants, and drug and gene delivery systems.