Exploration of alginates as potential stabilizers of nanosuspension

Nanosuspension Innovations: Expanding Horizons in Drug Delivery Techniques

Nanosuspensions (NS), with their submicron particle sizes and unique physicochemical properties, provide a versatile solution for enhancing the administration of medications that are not highly soluble in water or lipids. This review highlights recent advancements, future prospects, and challenges in NS-based drug delivery, particularly for oral, ocular, transdermal, pulmonary, and parenteral routes. The conversion of oral NS into powders, pellets, granules, tablets, and capsules, and their incorporation into film dosage forms to address stability concerns is thoroughly reviewed. This article summarizes key stabilizers, polymers, surfactants, and excipients used in NS formulations, along with ongoing clinical trials and recent patents. Furthermore, a comprehensive analysis of various methods for NS preparation is provided. This article also explores various in vitro and in vivo characterization techniques, as well as scale-down technologies and bottom-up methods for NS preparation. Selected examples of commercial NS drug products are discussed. Rapid advances in the field of NS could resolve issues related to permeability-limited absorption and hepatic first-pass metabolism, offering promise for medications based on proteins and peptides. The evolution of novel stabilizers is essential to overcome the current limitations in NS formulations, enhancing their stability, bioavailability, targeting ability, and safety profile, which ultimately accelerates their clinical application and commercialization.

Nanosuspensions as carriers of active ingredients: Chemical composition, development methods, and their biological activities

Nanosuspensions (NSps) are colloidal dispersions of particles that have the potential to solve the delivery problems of active ingredients associated with their low solubility in water or instability due to environmental factors. It is essential to consider their chemical composition and preparation methods because they directly influence drug loading, size, morphology, solubility, and stability; these characteristics of nanosuspensions influence the delivery and bioavailability of active ingredients. NSps provides high loading of drugs, protection against degrading agents, rapid dissolution, high particle stability, and high bioavailability of active ingredients across biological membranes. In addition, they provide lower toxicity compared to other nanocarriers, such as liposomes or polymeric nanoparticles, and can modify the pharmacokinetic profiles, thus improving their safety and efficacy. The present review aims to address all aspects related to the composition of NSps, the different methods for their production, and the main factors affecting their stability. Moreover, recent studies are described as carriers of active ingredients and their biological activities.

Nanosuspension: A Formulation Technology for Tackling the Poor Aqueous Solubility and Bioavailability of Poorly Soluble Drugs

The poor water solubility of numerous novel drug candidates presents significant challenges, particularly in terms of oral administration. This limitation can result in various undesirable clinical implications, such as inter-patient variability, poor bioavailability, difficulties in achieving a safe therapeutic index, increased costs, and potential risks of toxicity or inefficacy. Biopharmaceutics Classification System (BCS) class II drugs face particular hurdles due to their limited solubility in the aqueous media of the gastrointestinal tract. In such cases, parenteral administration is often employed as an alternative strategy. To address these challenges, nanosuspension techniques offer a promising solution for enhancing drug solubility and overcoming oral delivery obstacles. This technique has the potential to bridge the gap between drug discovery and preclinical use by resolving problematic solubility. This literature review has delved into contemporary nanosuspension preparation technologies and the incorporation of stabilizing ingredients within the formulation. Furthermore, the manuscript explores nanosuspension strategies for both oral and parenteral/other delivery routes, and separate discussions have been presented to establish a suitable flow that addresses the challenges and strategies relevant to each administration method.

A review of advances over 20 years on polysaccharide-based polymers applied as enhanced efficiency fertilizers

Over the last 20 years, polysaccharide-based materials have garnered attention in the enhanced efficiency fertilizers (EEFs) research. Biodegradability, non-toxicity, water-solubility, swellability, and ease of chemical modification make these polymers suitable for agricultural applications. In this review, the polysaccharides-based EEFs advances are summarized over the polymer and co-materials selection, the methods, and the chemical/structure aspects necessary for an appropriate production. We also briefly discuss terminologies, nutrient release mechanisms, biodegradation, and future trends. The most used polysaccharides are chitosan, starch, and alginate, and the non-Fickian model most describes the release mechanism. It is dependent on the relaxation of polymer chains by the matrix swelling followed by the nutrient diffusion. EEFs-polymers-based should be designed as more packed and less porous structures to avoid the immediate contact of the fertilizer with the surrounding water, improving fertilizer retention. Furthermore, the preparation methods will determine the scale-up of the material.

Exploring the potential of redispersible nanocomplex-in-microparticles for enhanced oral insulin delivery

Polyelectrolyte nanocomplex (PEC) is a promising carrier for insulin encapsulation. However, tenacious enzymatic degradation and insufficient penetration in mucus and enterocyte are the dominating obstacles for their oral insulin delivery. Besides, the rate of insulin release should be tuned to achieve desired therapeutic effect and meanwhile with scale-up potential. Thus, PEC embedded microparticles were fabricated in this study to solve the above dilemma. First of all, insulin loaded PEC with sodium dodecyl sulfate (SDS) coating was prepared by self-assembly method and then spray-dried using different ratio chitosan (CS)/ polyvinyl alcohol (PVA) as the matrix to obtain the microparticles. Influence of the CS/PVA ratio on the in vitro and in vivo properties of the redispersed PEC was investigated systemically. It was demonstrated that when CS 50 kDa was used in the matrix, all the PEC could be well redispersed with particle size less than 250 nm, and good stability in the gastrointestinal tract, further improved enzymatic stability was achieved by nanoparticles-in-microparticles design, with CS/PVA 1:1 and 4:1 groups showing better and comparable protection. Insulin release from the microparticles decreased with the increase of CS ratio in the CS/PVA matrix. Spray-dried microparticles had less influence on the mucus penetration of the in situ redispersed PEC, with enhanced insulin permeation observed in different intestinal segments in a CS/PVA ratio dependent manner. And the CS/PVA 1:1 group, which presented good enzymatic stability, enhanced mucus penetration and moderate insulin release rate, exhibited the highest relative pharmacological availability of 6.80%. In conclusion, PEC in microparticles design using CS/PVA as the composite matrix is a potential platform for enhanced oral insulin delivery.

An Enhanced Water Solubility and Stability of Anthocyanins in Mulberry Processed with Hot Melt Extrusion

Mulberry fruits are rich sources of anthocyanins that exhibit beneficial biological activity. These anthocyanins become instable in an aqueous media, leading to their low bioavailability. In this study, a colloidal dispersion was produced by processing mulberry samples with hot-melt extrusion. In this process, hydrophilic polymer matrices were used to disperse the compound in an aqueous media. Mulberry samples were processed with hot-melt extrusion and in the presence of an ionization agent and sodium alginate to form mulberry-extrudate solid formulations. The particle size of mulberry-extrudate solid formulations decreased, while the total phenol content, the total anthocyanin content, and solubility increased. Fourier transform infrared spectroscopy (FT-IR) revealed that mulberry-extrudate solid formulations now contained new functional groups, such as -COOH group. We investigated whether mulberry-extrudate solid formulations had a positive impact on the stability of anthocyanins. The non-extrudate mulberry sample and mulberry-extrudate solid formulations were incubated with a simulated gastric fluid system and an intestinal fluid system. The number of released anthocyanins was determined with HPLC. We found that anthocyanins were released rapidly from non-extrudate mulberry extract. Mulberry-extrudate solid formulations contained a large number of available anthocyanins even after being incubated for 180 min in the intestinal fluid system. Thus, hot-melt extrusion enhanced water solubility and stability of anthocyanins with the prolonged release.

Influence of Stabilizer on the Development of Luteolin Nanosuspension for Cutaneous Delivery: An In Vitro and In Vivo Evaluation

Luteolin is a natural drug used as an antioxidant and anti-inflammatory, but unfortunately, it possesses low water solubility, which hinders its delivery via the skin. The main objective of this study was to prepare a luteolin-loaded nanosuspension by the antisolvent precipitation/sonication technique and study the effects of four stabilizers (two nonionic stabilizers, Pluronic F127 and Tween 80, and two polymeric stabilizers, HPMC and alginate) on the physicochemical properties of the prepared formulations. The selected formulations were incorporated into a gel base to evaluate their skin permeability and anti-inflammatory efficacy. The particle size was in the nanosize range (in the range from 468.1 ± 18.6 nm to 1024.8 ± 15.9 nm), while the zeta potential was negative and in the range from −41.7 ± 6.3 mV to −15.3 ± 1.9 mV. In particular, alginate-stabilized nanosuspensions showed the smallest particle size, the highest zeta potential value, and excellent stability due to the dual stabilizing effects (electrostatic and steric effects). The DSC results revealed a less crystalline structure of luteolin in lyophilized NS2 and NS12. Formulations stabilized by 1% Pluronic (NS2) and 2% alginate (NS12) were incorporated into a carbopol 940 gel base and showed good organoleptic character (homogenous with no evidenced phase separation or grittiness). In vitro dissolution studies showed that NS12 enhanced luteolin release rates, indicating the effect of particle size on the drug release pattern. On the other hand, NS2 showed enhanced skin permeability and anti-inflammatory effect in a carrageenan-induced paw edema model, revealing the surface activity role of the stabilizers. In conclusion, while alginate increased the nanosuspension stability by means of dual stabilizing effects, Pluronic F127 improved the skin delivery and pharmacodynamic efficacy of luteolin.

Preparation of Nanocrystals for Insoluble Drugs by Top-Down Nanotechnology with Improved Solubility and Bioavailability

Midazolam is a rapidly effective benzodiazepine drug that is widely used as a sedative worldwide. Due to its poor solubility in a neutral aqueous solution, the clinical use of midazolam is significantly limited. As one of the most promising formulations for poorly water-soluble drugs, nanocrystals have drawn worldwide attention. We prepared a stable nanosuspension system that causes little muscle irritation. The particle size of the midazolam nanocrystals (MDZ/NCs) was 286.6 ± 2.19 nm, and the crystalline state of midazolam did not change in the size reduction process. The dissolution velocity of midazolam was accelerated by the nanocrystals. The pharmacokinetics study showed that the AUC0-t of the MDZ/NCs was 2.72-fold (p < 0.05) higher than that of the midazolam solution (MDZ/S), demonstrating that the bioavailability of the MDZ/NC injection was greater than that of MDZ/S. When midazolam was given immediately after the onset of convulsions, the ED50 for MDZ/NCs was significantly more potent than that for MDZ/S and DZP/S. The MDZ/NCs significantly reduced the malondialdehyde content in the hippocampus of the seizures model rats and significantly increased the glutathione and superoxide dismutase levels. These results suggest that nanocrystals significantly influenced the dissolution behavior, pharmacokinetic properties, anticonvulsant effects, and neuroprotective effects of midazolam and ultimately enhanced their efficacy in vitro and in vivo.

Advanced modification of drug nanocrystals by using novel fabrication and downstream approaches for tailor-made drug delivery

Drug nanosuspensions/nanocrystals have been recognized as one useful and successful approach for drug delivery. Drug nanocrystals could be further decorated to possess extended functions (such as controlled release) and designed for special in vivo applications (such as drug tracking), which make best use of the advantages of drug nanocrystals. A lot of novel and advanced size reduction methods have been invented recently for special drug deliveries. In addition, some novel downstream processes have been combined with nanosuspensions, which have highly broadened its application areas (such as targeting) besides traditional routes. A large number of recent research publication regarding as nanocrystals focuses on above mentioned aspects, which have widely attracted attention. This review will focus on the recent development of nanocrystals and give an overview of regarding modification of nanocrystal by some new approaches for tailor-made drug delivery.

Influence of stabilizer type and concentration on the lung deposition and retention of resveratrol nanosuspension-in-microparticles

The purpose of this study was to explore the influence of stabilizer type and concentration on the properties of spray dried nanosuspension-in-microparticles (NS-in-MPs) for inhalation. Taking resveratrol (RES) as a Biopharmaceutical Classification System II (BCS II) model drug, the RES containing nanosuspensions were fabricated by high pressure homogenization method with different stabilizers including sodium dodecyl sulphate (SDS), sodium alginate (SA), chitosan (CS) and polyvinyl alcohol (PVA). Then, the nanosuspensions were spray dried with mannitol to obtain inhalable NS-in-MPs. The particle size, morphology, drug existing state, in vitro aerodynamic performance, in vitro release behavior, lung retention and pharmacokinetic behaviors were characterized. It was found that the morphology, lung deposition as well as in vitro drug release from the microparticles were significantly influenced by stabilizer type, with 1% PVA as stabilizer presenting the highest fine particle fraction (FPF). Meanwhile, taking PVA as an example, it was found stabilizer concentration could alter morphology and flowability of the microparticles, and the FPF value decreased with the increase of stabilizer concentration. Further drug retention and in vivo pharmacokinetic studies demonstrated that the positively charged stabilizer CS could facilitate drug retention and minimize drug expose to the systemic circulation. In conclusion, the deposition and lung retention behavior of NS-in-MPs could be well tuned by selecting different type or concentration of stabilizers, which could facilitate local lung diseases therapy.

Synergistic effect of Soluplus and hyaluronic acid on the supersaturation maintenance of lovastatin: The facilitated in vitro-in vivo performance and improved physical stability

The objective of present study was to explore whether polysaccharide could be employed as potential crystal growth inhibitor and provides synergistic effect on the supersaturation maintaining of lovastatin (LOV) in combination of nucleation inhibitor. Soluplus (SOL) and hyaluronic acid (HA) were selected as the most effective nucleation and crystal growth inhibitor respectively. The interaction between SOL and HA was elucidated via characterizing the particle size, zeta potential, surface hydrophobicity, solvent relaxation time (T₂) and FT-IR. The supersaturated drug solution was spray dried into amorphous solid dispersion, then, the in vitro release, moisture uptake and physical stability were investigated. The synergistic effect between SOL and HA was dependent on drug concentration, drug/carrier and SOL/HA weight ratio, which facilitated both in vitro and in vivo performance. It was disclosed that HA could insert into SOL structure providing both electrostatic and steric stabilization. In conclusion, the combination of nucleation and crystal growth inhibitors is a promising approach for supersaturated drug delivery system.

Synergetic effect of nucleation and crystal growth inhibitor on in vitro-in vivo performance of supersaturable lacidipine solid dispersion

Limited supersaturation maintaining duration is the main challenge for amorphous solid dispersion design. Nucleation or crystal growth inhibitors may function in different ways but the combination use of nucleation and crystal growth inhibitors in supersaturated system is rarely explored. Thus, using Lacidipine (LCDP) as a Biopharmaceutical Classification System (BCS) II model drug, the aim of this study was to explore whether the combination use of nucleation and crystal growth inhibitors could provide a synergistic effect on the in vitro-in vivo performance of poorly water-soluble drugs. First of all, based on compatibility screening using solubility parameter (Δδ) and crystallization inhibition efficiency as criteria, soluplus (SOL) and gum arabic (GA) were selected as the most effective nucleation and crystal growth inhibitor respectively. Thereafter, the supersaturated drug solutions were spray dried and characterized. The in vitro release, physical stability as well as pharmacokinetic behavior were investigated. It was found that the combination use of SOL and GA did not present remarkable advantage in prolonging the supersaturation time in solution state. However, their synergistic effect in equilibrium solubility and dissolution enhancement was noticed at SOL/GA ratio 3:1, with 5-7 times higher dissolution rate observed for LCDP/SOL/GA based formulation compared with that of LCDP/SOL, which was maintained even after three months accelerated stability test under non-sink condition. Moreover, compared to the LCDP/SOL formulation, approximately 2.8 and 2.5-fold increase in the maximum plasma concentration (C_max) and the area under the plasma-time curve (AUC_0-∞) was achieved with LCDP/SOL/GA based formulation. Possible mechanism of the synergistic effect was elucidated, indicating GA may penetrate into SOL particles providing both electrostatic and steric stabilization. In conclusion, the combination use of screened nucleation and crystal growth inhibitors might be an efficient approach to design supersaturated drug delivery system.

Formulation and Evaluation of a Novel Oral Oil-Based Suspension Using Micro-environmental pH-Modifying Solid Dispersion

Drugs with pH-dependent solubility that have poor water solubility can be identified in the drug discovery pipeline. Some of them have poor oral absorption, which can result in insufficient efficacy. Micro-environmental pH-modifying solid dispersion (micro pHm SD) is a promising approach to overcome the poor oral absorption of these drugs. In the present study, toltrazuril (TOL), a weakly acidic drug with poor aqueous and pH-dependent solubility, was used as a model drug. Using micro pHm SD, a novel oral oil-based suspension of TOL SD (TSDS) was developed, and the stability of this formulation was evaluated based on particle size, settling volume ratio, redispersibility, thermal stability, and drug content. The optimized soybean oil-based TSDS (S-TSDS) had high physicochemical stability and good histocompatibility with common inflammatory reactions. The results of the in vitro dissolution analysis showed that S-TSDS rapidly and markedly released the drug and provided higher efficacy and longer persistence against coccidiosis (above 90.9%) in rabbits. This technique could increase the oral absorption and bioavailability of new drug candidates.

Nanoparticle-in-microparticle oral drug delivery system of a clinically relevant darunavir/ritonavir antiretroviral combination

Nanonizationhas been extensively investigated to increase theoral bioavailability of hydrophobicdrugsin general andantiretrovirals(ARVs)used inthe therapy of the human immunodeficiency virus (HIV) infection in particular. Weanticipatedthatin the caseofprotease inhibitors, a family of pH-dependent ARVsthatdisplay high aqueous solubility undertheacidconditionsof thestomach andextremely low solubilityunder the neutral ones ofthe small intestine, this strategy might failowing to an uncontrolled dissolution-re-precipitation process that will take place along the gastrointestinal tract.To tackle thisbiopharmaceutical challenge, in this work, wedesigned, produced and fully characterized a novelNanoparticle-in-MicroparticleDelivery System(NiMDS)comprised of pure nanoparticlesofthefirst-line protease inhibitor darunavir(DRV) and itsboosting agentritonavir (RIT) encapsulated within film-coated microparticles.For this, a clinically relevant combination of pure DRV and RIT nanoparticles wassynthesized by a sequential nanoprecipitation/solvent diffusion and evaporation method employing sodium alginateas viscosity stabilizer. Then, pure nanoparticles were encapsulated within calcium alginate/chitosanmicroparticlesthat were film-coated with a series ofpoly(methacrylate) copolymers with differential solubility in the gastrointestinal tract. This coating ensured full stability under gastric-like pH and sustained drug release under intestinal one. PharmacokineticstudiesconductedinalbinoSpragueDawleyratsshowed that DRV/RIT-loadedNiMDSs containing 17% w/w drug loading based on dry weight significantlyincreasedthe oral bioavailabilityof DRVby 2.3-foldwith respect to both theunprocessedandthenanonized DRV/RIT combinations that showed statistically similar performance. Moreover, they highlighted the limited advantage of only drugnanonizationto improve the oral pharmacokinetics of protease inhibitors and the potential of our novel delivery approach to improve the oral pharmacokinetics of nanonized poorly water-soluble drugs displaying pH-dependent solubility.

STATEMENT OF SIGNIFICANCE

Protease inhibitors (PIs) are gold-standard drugs in many ARV cocktails. Darunavir (DRV) is the latest approved PI and it is included in the 20th WHO Model List of Essential Medicines. PIs poorly-water soluble at intestinal pH and more soluble under gastric conditions. Drug nanonization represents one of the most common nanotechnology strategies to increase dissolution rate of hydrophobic drugs and thus, their oral bioavailability. For instance, pure drug nanosuspensions became the most clinically relevant nanoformulation. However, according to the physicochemical properties of PIs, nanonization does not appear as a very beneficial strategy due to the fast dissolution rate anticipated under the acid conditions of the stomach and their uncontrolled recrystallization and precipitation in the small intestine that might result in the formation of particles of unpredictable size and structure (e.g., crystallinity and polymorphism) and consequently, unknown dissolution rate and bioavailability. In this work, we developed a sequential nanoprecipitation method for the production of pure nanoparticles of DRV and its boosting agent ritonavir in a clinically relevant 8:1 wt ratio using alginate as viscosity stabilizer and used this nanosuspension to produce a novel kind of nanoparticle-in-microparticle delivery system that was fully characterized and the pharmacokinetics assessed in rats. The most significant points of the current manuscript are.

Preparation and Evaluation of Progesterone Nanocrystals to Decrease Muscle Irritation and Improve Bioavailability

Progesterone (PG) is a crucial immunomodulatory agent during early pregnancy, and nowadays PG oil-based injection (PG/OI) has a huge market all over the world. However, PG/OI may accumulate the local muscle and further cause irritations after long-term administration. In this study, PG nanocrystals (PG/NCs) injection was developed to decrease muscle toxicity. PG/NCs injection containing 10% (w/v) PG was first prepared using a wet grinding method. Then, particle size, zeta potential, morphology powder, X-ray diffraction (PXRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) studies were carried out to evaluate the characteristics of dosage form. The rabbit muscle irritation, hemolysis, and rat pharmacokinetics tests were used to estimate the in vivo characteristics of PG/NCs. The results showed that the mean particle size and the zeta potentials of NCs were 299.5 ± 9.0 nm and - 36.8 ± 1.5 mV, respectively. The crystalline state of PG/NCs was not altered during particle size reduction according to PXRD, DSC, and FTIR results. Muscle irritation presented that PG/NCs had lower irritation than that of PG/OI. Hemolysis test suggested that PG/NCs injection was functioned without hemolysis and red cell agglutination. The pharmacokinetics study showed that the AUC_0-t and C_max of PG/NCs was 3.2-fold (p < 0.05) and 3.1-fold higher than PG/OI, which demonstrated that PG/NCs injection had greater bioavailability than PG/OI. Therefore, it was obvious that PG/NCs injection exhibited a lower muscle irritation, hemolysis rate, and higher bioavailability, which was a better dosage form than OI.