Novel continuous flow technology for the development of a nanostructured aprepitant formulation with improved pharmacokinetic properties

PVP/aprepitant microcapsules produced by supercritical antisolvent process

The supercritical antisolvent (SAS) process was a green alternative to improve the low bioavailability of insoluble drugs. However, it is difficult for SAS process to industrialize with limited production capacity. A coaxial annular nozzle was used to prepare the microcapsules of aprepitant (APR) and polyvinylpyrrolidone (PVP) by SAS with N, N-Dimethylformamide (DMF) as solvent. Meanwhile, the effects of polymer/drug ratio, operating pressure, operating temperature and overall concentration on particles morphology, mean particle diameter and size distribution were analyzed. Microcapsules with mean diameters ranging from 2.04 μm and 9.84 μm were successfully produced. The morphology, particle size, thermal behavior, crystallinity, drug content, drug dissolution and residual amount of DMF of samples were analyzed. The results revealed that the APR drug dissolution of the microcapsules by SAS process was faster than the unprocessed APR. Furthermore, the drug powder collected every hour is in the kilogram level, verifying the possibility to scale up the production of pharmaceuticals employing the SAS process from an industrial point of view.

A Novel Semi-Solid Self-Emulsifying Formulation of Aprepitant for Oral Delivery: An In Vitro Evaluation

Aprepitant is the first member of a relatively new antiemetic drug class called NK₁ receptor antagonists. It is commonly prescribed to prevent chemotherapy-induced nausea and vomiting. Although it is included in many treatment guidelines, its poor solubility causes bioavailability issues. A particle size reduction technique was used in the commercial formulation to overcome low bioavailability. Production with this method consists of many successive steps that cause the cost of the drug to increase. This study aims to develop an alternative, cost-effective formulation to the existing nanocrystal form. We designed a self-emulsifying formulation that can be filled into capsules in a melted state and then solidified at room temperature. Solidification was achieved by using surfactants with a melting temperature above room temperature. Various polymers have also been tested to maintain the supersaturated state of the drug. The optimized formulation consists of Capryol^TM 90, Kolliphor^® CS20, Transcutol^® P, and Soluplus^®; it was characterized by DLS, FTIR, DSC, and XRPD techniques. A lipolysis test was conducted to predict the digestion performance of formulations in the gastrointestinal system. Dissolution studies showed an increased dissolution rate of the drug. Finally, the cytotoxicity of the formulation was tested in the Caco-2 cell line. According to the results, a formulation with improved solubility and low toxicity was obtained.

Improved anticancer efficacy of methyl pyropheophorbide-a-incorporated solid lipid nanoparticles in photodynamic therapy

Photodynamic therapy (PDT) is a promising anticancer treatment because it is patient-friendly and non-invasive. Methyl pyropheophorbide-a (MPPa), one of the chlorin class photosensitizers, is a drug with poor aqueous solubility. The purpose of this study was to synthesize MPPa and develop MPPa-loaded solid lipid nanoparticles (SLNs) with improved solubility and PDT efficacy. The synthesized MPPa was confirmed ¹H nuclear magnetic resonance (¹H-NMR) spectroscopy and UV-Vis spectroscopy. MPPa was encapsulated in SLN via a hot homogenization with sonication. Particle characterization was performed using particle size and zeta potential measurements. The pharmacological effect of MPPa was evaluated using the 1,3-diphenylisobenzofuran (DPBF) assay and anti-cancer effect against HeLa and A549 cell lines. The particle size and zeta potential ranged from 231.37 to 424.07 nm and - 17.37 to - 24.20 mV, respectively. MPPa showed sustained release from MPPa-loaded SLNs. All formulations improved the photostability of MPPa. The DPBF assay showed that SLNs enhanced the ¹O₂ generation from MPPa. In the photocytotoxicity analysis, MPPa-loaded SLNs demonstrated cytotoxicity upon photoirradiation but not in the dark. The PDT efficacy of MPPa improved following its entrapment in SLNs. This observation suggests that MPPa-loaded SLNs are suitable for the enhanced permeability and retention effect. Together, these results demonstrate that the developed MPPa-loaded SLNs are promising candidates for cancer treatment using PDT.

Design and Characterization of Phosphatidylcholine-Based Solid Dispersions of Aprepitant for Enhanced Solubility and Dissolution

This study aimed to improve the solubility and dissolution of aprepitant, a drug with poor aqueous solubility, using a phosphatidylcholine (PC)-based solid dispersion system. When fabricating the PC-based solid dispersion, we employed mesoporous microparticles, as an adsorbent, and disintegrants to improve the sticky nature of PC and dissolution of aprepitant, respectively. The solid dispersions were prepared by a solvent evaporation technique and characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry, and X-ray powder diffraction. The FTIR results showed that aprepitant interacted with the PC carrier by both hydrogen bonds and van der Waals forces that can also be observed in the interaction between aprepitant and polymer carriers. The solid dispersions fabricated with only PC were not sufficient to convert the crystallinity of aprepitant to an amorphous state, whereas the formulations that included adsorbent and disintegrant successfully changed that of aprepitant to an amorphous state. Both the solubility and dissolution of aprepitant were considerably enhanced in the PC-based solid dispersions containing adsorbent and disintegrant compared with those of pure aprepitant and polymer-based solid dispersions. Therefore, these results suggest that our PC-based solid dispersion system is a promising alternative to conventional formulations for poorly water-soluble drugs, such as aprepitant.

Aprepitant Intravenous Emulsion Based on Ion Pairing/Phospholipid Complex for Improving Physical and Chemical Stability During Thermal Sterilization

An aprepitant (APT) cholesteryl hemisuccinate (CHEMS) ion pair complex emulsion (AIPE) with high lecithin content was prepared to improve sterilization stability through the film dispersion homogenization method; therefore, it could be a promising delivery system of APT. Medium-chain triglycerides (MCT) was selected as the oil phase to improve the solubility and stability of APT in oil phase. DSC, XRD, FT-IR, and ¹H-NMR spectroscopies confirmed that the APT-CHEMS ion pair (AIP) was formed between CHEMS and APT. The formation of AIP significantly increased the hydrophobicity of APT, allowing it to be completely embedded in the oil phase core to improve chemical stability and decrease hydrolysis of APT in the water phase. Also, CHEMS had a strong affinity with lecithin and could stabilize lipid membranes, forming a stronger and thicker interface membrane to increase the physical stability of AIPE. As a result, AIPE could withstand autoclaving at 120°C for 8 min without any change of particle size or content. Furthermore, AIPE with a potential of - 53.4 mV remained stable through spatial repulsion during sterilization. The encapsulation efficiency of AIPE was over 90% and the particle size was 106.8 ± 65.62 nm(0.286). Pharmacokinetic study in rats was comparable with that of CINVANTI which yielded a relative bioavailability of 114.31% indicating that the AIPE had similar pharmacokinetic processes in vivo with the analog of CINVANTI®. The AUC0-t of the AIPE was 4.31-fold that of the APT solution.

Evaluation of Dissolution Enhancement of Aprepitant Drug in Ternary Pharmaceutical Solid Dispersions with Soluplus® and Poloxamer 188 Prepared by Melt Mixing

In the present study Aprepitant (APT) ternary solid dispersions (SDs) were developed and evaluated for the first time. Specifically, ternary SDs of APT with Poloxamer 188 and Soluplus® (SOL) were prepared via melt mixing and compared to binary APT/Poloxamer 188 and APT/SOL SDs. Initially, combined thermo-gravimetric and hot-stage polarized light microscopy studies indicated that all tested compounds were thermally stable up to 280 °C, while Poloxamer 188 acted as a plasticizer to SOL by significantly reducing the temperature required to fully solubilize the API during SD preparation. Differential scanning calorimetry combined with wide angle X-ray diffraction studies showed that crystalline API was dispersed in both binary and ternary SDs, while Fourier transformation-infrared spectroscopy studies revealed no molecular interactions among the components. Scanning electron microscopy combined with EDAX element analysis showed that the API was dispersed in nano-scale within the polymer matrices, while increasing APT content led to increasing API nano-crystals within the SDs. Finally, dissolution studies showed that the prepared formulations enhanced dissolution of Aprepitant and its mechanism analysis was further studied. A mathematical model was also investigated to evaluate the drug release mechanism.

Aprepitant Drug in Ternary Pharmaceutical Solid Dispersions with Soluplus® and Poloxamer 188 Prepared by Melt Mixing

In the present study Aprepitant (APT) ternary solid dispersions (SDs) were developed and evaluated for the first time. Specifically, ternary SDs of APT with Poloxamer 188 and Soluplus® (SOL) were prepared via melt mixing and compared to binary APT/Poloxamer 188 and APT/SOL SDs. Initially, combined thermo-gravimetric and hot-stage polarized light microscopy studies indicated that all tested compounds were thermally stable up to 280 °C, while Poloxamer 188 acted as a plasticizer to SOL by significantly reducing the temperature required to fully solubilize the API during SD preparation. Differential scanning calorimetry combined with wide angle X-ray diffraction studies showed that crystalline API was dispersed in both binary and ternary SDs, while Fourier transformation-infrared spectroscopy studies revealed no molecular interactions among the components. Scanning electron microscopy combined with EDAX element analysis showed that the API was dispersed in nano-scale within the polymer matrices, while increasing APT content led to increasing API nano-crystals within the SDs. Finally, dissolution studies showed that the prepared formulations enhanced dissolution of Aprepitant and its mechanism analysis was further studied. A mathematical model was also investigated to evaluate the drug release mechanism

Development of a New Aprepitant Liquisolid Formulation with the Aid of Artificial Neural Networks and Genetic Programming

In the present study, liquisolid formulations were developed for improving dissolution profile of aprepitant (APT) in a solid dosage form. Experimental studies were complemented with artificial neural networks and genetic programming. Specifically, the type and concentration of liquid vehicle was evaluated through saturation-solubility studies, while the effect of the amount of viscosity increasing agent (HPMC), the type of wetting (Soluplus® vs. PVP) and solubilizing (Poloxamer®407 vs. Kolliphor®ELP) agents, and the ratio of solid coating (microcrystalline cellulose) to carrier (colloidal silicon dioxide) were evaluated based on in vitro drug release studies. The optimum liquisolid formulation exhibited improved dissolution characteristics compared to the marketed product Emend®. X-ray diffraction (XRD), scanning electron microscopy (SEM) and a novel method combining particle size analysis by dynamic light scattering (DLS) and HPLC, revealed that the increase in dissolution rate of APT in the optimum liquisolid formulation was due to the formation of stable APT nanocrystals. Differential scanning calorimetry (DSC) and attenuated total reflection FTIR spectroscopy (ATR-FTIR) revealed the presence of intermolecular interactions between APT and liquisolid formulation excipients. Multilinear regression analysis (MLR), artificial neural networks (ANNs), and genetic programming (GP) were used to correlate several formulation variables with dissolution profile parameters (Y _15min and Y _30min) using a full factorial experimental design. Results showed increased correlation efficacy for ANNs and GP (RMSE of 0.151 and 0.273, respectively) compared to MLR (RMSE = 0.413).

Pokharkar V. Understanding peroral absorption: regulatory aspects and contemporary approaches to tackling solubility and permeability hurdles

Oral drug absorption is a process influenced by the physicochemical and biopharmaceutical properties of the drug and its inter-relationship with the gastrointestinal tract. Drug solubility, dissolution and permeability across intestinal barrier are the key parameters controlling absorption. This review provides an overview of the factors that affect drug absorption and the classification of a drug on the basis of solubility and permeability. The biopharmaceutical classification system (BCS) was introduced in early 90׳s and is a regulatory tool used to predict bioavailability problems associated with a new entity, thereby helping in the development of a drug product. Strategies to combat solubility and permeability issues are also discussed.

Analytical ultracentrifugation for analysis of doxorubicin loaded liposomes

Analytical ultracentrifugation (AUC) is a powerful tool for the study of particle size distributions and interactions with high accuracy and resolution. In this work, we show how the analysis of sedimentation velocity data from the AUC can be used to characterize nanocarrier drug delivery systems used in nanomedicine. Nanocarrier size distribution and the ratio of free versus nanoparticle-encapsulated drug in a commercially available liposomal doxorubicin formulation are determined using interference and absorbance based AUC measurements and compared with results generated with conventional techniques. Additionally, the potential of AUC in measuring particle density and the detection of nanocarrier sub-populations is discussed as well. The unique capability of AUC in providing reliable data for size and composition in a single measurement and without complex sample preparation makes this characterization technique a promising tool both in nanomedicine product development and quality control.

Transmembrane Pathways and Mechanisms of Rod-like Paclitaxel Nanocrystals through MDCK Polarized Monolayer

Drug nanocrystals (NCs) appear to be favorable to improving oral bioavailability of poorly water-soluble drugs as evidenced by the great success they have had in the market. However, the pathway and mechanism of drug NCs through epithelial membrane are still unclear. In an attempt to clarify their transport features, paclitaxel nanocrystals (PTX-NCs), and paclitaxel hybrid NCs with lipophilic carbocyanine dyes, were prepared and characterized as the models. The endocytosis, intracellular trafficking, paracellular transport, and transcytosis of PTX-NCs were carefully investigated with Förster resonance energy transfer (FRET) analysis, as well as a colocalization assay, flow cytometry, gene silencing, Western-blot, transepithelial electrical resistance (TEER) study and other approaches on MDCK cells. It was found that rod-like PTX-NCs could transport through the monolayer intact, and the process of endocytosis proved to be time and energy dependent. Endoplasmic reticulum (ER) and Golgi complexes were colocalized with PTX-NCs in cells, so the ER-Golgi complexes/Golgi complexes-basolateral membrane pathway may be involved in the intracellular trafficking and transcytosis of PTX-NCs. It was demonstrated here that cav-1, dynamin, and actin filament modulated the endocytosis process, and Cdc 42 regulated the transcytosis process. In addition, no paracellular transport of PTX-NCs was observed. These findings demonstrated that the rod-like nanocrystals not only enhanced the transcytosis of PTX compared with microparticles of raw drug materials but also changed the pathways of drug delivery. This study certainly provides insight for the oral absorption mechanism of nanocrystals of poorly soluble drugs.

Development of aprepitant loaded orally disintegrating films for enhanced pharmacokinetic performance

The present investigation was aimed to prepare orally disintegrating films (ODFs) containing aprepitant (APT), an antiemetic drug employing pullulan as film forming agent, tamarind pectin as wetting agent and liquid glucose as plasticizer and solubiliser. The ODFs were prepared using solvent casting method. The method was optimized employing 3(2) full factorial design considering proportion of pullulan: tamarind pectin and concentration of liquid glucose as independent variables and disintegration time, wetting time, folding endurance, tensile strength and extensibility as dependent variables. The optimized ODF was evaluated for various physicochemical, mechanical, drug release kinetics and bioavailability studies. The results suggested prepared film has uniform film surface, non-sticky and disintegrated within 18s. The in-vitro release kinetics revealed more than 87% aprepitant was released from optimized ODF as compared to 85%, 49%, and 12% aprepitant release from marketed formulation Aprecap, micronized aprepitant and non micronized aprepitant, respectively. The results of animal preference study indicated that developed aprepitant loaded ODFs are accepted by rabbits as food material. Animal pharmacokinetic (PK) study showed 1.80, 1.56 and 1.36 fold enhancement in relative bioavailability for aprepitant loaded ODF, Aprecap and micronized aprepitant respectively, in comparison with non-micronized aprepitant. Overall, the solubilised aprepitant when incorporated in the form of aprepitant loaded ODF showed enhanced bioavailability as compared to micronized/non-micronized aprepitant based oral formulations. These findings suggested that aprepitant loaded ODF could be effective for antiemesis during cancer chemotherapy.

Aprepitant loaded solid preconcentrated microemulsion for enhanced bioavailability: A comparison with micronized Aprepitant

Aprepitant (APT) is a lipophilic, poorly water soluble drug with moderate permeability characteristic. Therefore, we aimed to improve solubility as well as permeability that could possibly improve oral bioavailability of APT. For this purpose, Quality by design (QbD) approach employing simplex lattice mixture design was used to prepare solid preconcentrated microemulsion (S-PCM). Further, the software generated numerically optimized S-PCM formulations were developed by utilizing desirability function. The spectral attributes (powder X-ray diffraction, ATR-FTIR, and differential scanning calorimetry) of S-PCM formulations suggested that APT was present in amorphous form. The results of droplet size (150-180 nm), zeta potential (-13 to -15 mV), poly dispersity index (PDI) (0.211-0.238) and emulsification time (<1 min), of these S-PCM formulations (SP1, SP2 and SP3) suggested spherical shape morphology (Transmission electron microscopy) with thermodynamic stability. The comparison of in vitro/ex vivo behavior of S-PCM (SP1) with micronized and non-micronized formulations of APT suggested 2-fold and 5-fold enhancement in solubility and permeability, respectively. This was further evident from pharmacokinetic studies in rabbits that showed 1.5-fold enhancement in bioavailability of S-PCM with respect to micronized APT. Thus, it could be envisaged that development of S-PCM formulation of APT is the best alternative to micronization technology based APT formulations reported earlier.

Nanoparticles in drug delivery: mechanism of action, formulation and clinical application towards reduction in drug-associated nephrotoxicity

INTRODUCTION

Over the past few decades, nanoparticles (NPs) have gained immeasurable interest in the field of drug delivery. Various NP formulations have been disseminated in drug development in an attempt to increase efficacy, safety and tolerability of incorporated drugs. In this context, NP formulations that increase solubility, control release, and/or affect the in vivo disposition of drugs, were developed to improve the pharmacokinetic and pharmacodynamic properties of encapsulated drugs.

AREAS COVERED

In this article, important properties related to NP function such as particle size, surface charge and shape are disseminated. Also, the current understanding of how NP characteristics affect particle uptake and targeted delivery is elucidated. Selected NP systems currently used in delivery of drugs in biological systems and their production methods are discussed as well. Emphasis is placed on current NP formulations that are shown to reduce drug-induced adverse renal complications.

EXPERT OPINION

Formulation designs utilizing NP-encapsulated drugs offer alternative pharmacotherapy options with improved safety profiles for current and emerging drugs. NPs have been shown to increase the therapeutic index of several entrapped drugs mostly by decreasing drug localization and side effects on organs. Recent studies on NP-encapsulated chemotherapeutic and antibiotic medications show enhanced therapeutic outcomes by altering drug degradation, increasing systemic circulation and/or enhancing cell specific targeting. They may also reduce the distribution of encapsulated drugs into the kidneys and attenuate drug-associated adverse renal complications. The usefulness of NP formulation in reducing the nephrotoxicity of nonsteroidal anti-inflammatory drugs is an under explored territory that deserves more attention.