Influence of polyvinylpyrrolidone quantity on the solubility, crystallinity and oral bioavailability of fenofibrate in solvent-evaporated microspheres

Naringenin nanocrystals for improving anti-rheumatoid arthritis activity

Naringenin (NAR) is recognized for its anti-inflammatory activity. However, the clinical application of NAR is limited by low bioavailability, which is attributed to its poor aqueous solubility. In this study, we aimed to improve the therapeutic efficacy of NAR by formulating it into nanocrystals (NCs) via wet milling. The obtained NARNCs exhibited superior dissolution behaviors, increased cellular uptake, and enhanced transcellular diffusion relative to those of bulk NAR. Oral administration of NARNCs also significantly improved bioavailability in rats. In addition, the NARNCs effectively improved rheumatoid arthritis treatment in collagen-induced arthritic rats by reducing inflammatory cell infiltration and synovial damage. These results indicate that NARNCs provides a promising strategy for rheumatoid arthritis treatment.

Development of rebamipide-loaded spray-dried microsphere using distilled water and meglumine: physicochemical characterization and pharmacokinetics in rats

In this study, a novel rebamipide-loaded spray-dried microsphere (RSM) with enhanced drug solubility and oral bioavailability has been developed utilizing meglumine, an alkalizing agent. The influence of carriers on the drug solubility alone, and the solubility and dissolution of the drug in the RSM was investigated. Among the alkalizing agents and hydrophilic polymers tested, meglumine and polyvinyl alcohol (PVA) showed the highest drug solubility and dissolution rate, respectively. Many RSMs were manufactured with various amounts of meglumine and PVA using distilled water, and their drug solubility and dissolution were determined. The physicochemical properties, dissolution and pharmacokinetics of the chosen RSM in rats were assessed compared to the rebamipide powder and commercial tablet. Among the RSMs tested, the one composed of rebamipide, meglumine and PVA at a weight ratio of 3:1.75:6 showed the highest drug solubility and dissolution. This RSM with a smooth spherical form significantly decreased the particle size and modified the amorphous rebamipide. Furthermore, the drug solubility, dissolution, plasma concentrations, AUC and C_max values of RSM were significantly higher than those of drug powder and commercial tablet. Thus, this RSN system developed with distilled water and meglumine is recommended as an oral water-soluble rebamipide-loaded pharmaceutical product.

Multifunctional Role of Polyvinylpyrrolidone in Pharmaceutical Formulations

Polyvinylpyrrolidone (PVP), a non-ionic polymer, has been employed in multifarious fields such as paper, fibers and textiles, ceramics, and pharmaceutics due to its superior properties. Especially in pharmacy, the properties of inertness, non-toxicity, and biocompatibility make it a versatile excipient for both conventional formulations and novel controlled or targeted delivery systems, serving as a binder, coating agent, suspending agent, pore-former, solubilizer, stabilizer, etc. PVP with different molecular weights (MWs) and concentrations is used in a variety of formulations for different purposes. In this review, PVP-related researches mainly in recent 10 years were collected, and its main pharmaceutical applications were summarized as follows: (i) improving the bioavailability and stability of drugs, (ii) improving the physicomechanical properties of preparations, (iii) adjusting the release rate of drugs, and (iv) prolonging the in vivo circulation time of liposomes. Most of these applications could be explained by the viscosity, solubility, hydrophilicity, and hydrogen bond-forming ability of PVP, and the specific action mechanisms for each application were also tried to figure out. The effect of PVP on bioavailability improvement establishes it as a promising polymer in the emerging controlled or targeted formulations, attracting growing interest on it. Therefore, given its irreplaceability and tremendous opportunities for future developments, this review aims to provide an informative reference about current roles of PVP in pharmacy for interested readers.

Development of novel tenofovir disoproxil phosphate salt with stability enhancement and bioequivalence to the commercial tenofovir disoproxil fumarate salt in rats and beagle dogs

Tenofovir disoproxil (TD) is very unstable in the solid state under storage conditions. Moreover, tenofovir disoproxil fumarate (TDF), a commercial salt, is chemically unstable in alkaline solution. In this study, a novel tenofovir disoproxil phosphate (TDP), with stability enhancement and bioequivalence to commercial TDF in rats and beagle dogs, has been developed as an alternative. The TDP and its tablets were easily manufactured, and its physicochemical properties, such as morphology, crystallinity, solubility, lipophilicity and stability were investigated and compared to TD and TDF. Its dissolution and pharmacokinetics were investigated in rats and beagle dogs in comparison to TD and TDF. TDP appeared as an irregularly-shaped crystalline powder with a rough surface, like TDF. However, TDP significantly improved the solubility (7.4 ± 1.3 vs. 28.6 ± 1.0 mg/ml), hydrophilicity (Log P, 0.58 ± 0.03 vs. 0.47 ± 0.04), and aqueous stability (drug concentration over 12 h at pH 6.8 84.0 ± 2.0% vs. 88.2 ± 1.5%) of TD compared to TDF. The TDP gave no significant different plasma concentrations, AUC and C_max compared to TDF in rats (AUC, 1242.1 ± 584.9 vs. 825.9 ± 79.5 h·ng/ml; C_max, 154.8 ± 25.4 vs. 210.9 ± 70.3 ng/ml). Moreover, the TDP-loaded tablets were stable for at least six months and provided similar dissolution and bioequivalence to the TDF-loaded commercial product in beagle dogs (AUC, 26,832.7 ± 4093.0 vs. 26,605.3 ± 2530.1 h·ng/ml; C_max, 4364.0 ± 2061.9 vs. 4186.3 ± 2616.5 ng/ml). Therefore, as an alternative salt, the TDP would be a recommendable candidate with stability enhancement and bioequivalence to the commercial TDF.

Revaprazan-loaded surface-modified solid dispersion: physicochemical characterization and in vivo evaluation

The purpose of this research was to develop a novel revaprazan-loaded surface-modified solid dispersion (SMSD) with improved drug solubility and oral bioavailability. The impact of carriers on aqueous solubility of revaprazan was investigated. HPMC and Cremophor A25 were selected as an appropriate polymer and surfactant, respectively, due to their high drug solubility. Numerous SMSDs were prepared with various concentrations of carriers, using distilled water, and the drug solubility of each was assessed. Moreover, the physicochemical properties, dissolution and pharmacokinetics of selected SMSD in rats were assessed in comparison to revaprazan powder. Of the SMSDs assessed, the SMSD composed of revaprazan/HPMC/Cremophor A25 at the weight ratio of 1:0.28:1.12 had the most enhanced drug solubility (∼6000-fold). It was characterized by particles with a relatively rough surface, suggesting that the carriers were attached onto the surface of the unchanged crystalline revaprazan powder. It had a significantly higher dissolution rate, AUC and C_max, and a faster T_max value in comparison to revaprazan powder, with a 5.3-fold improvement in oral bioavailability of revaprazan. Therefore, from an environmental perspective, this SMSD system prepared with water, and without organic solvents, should be recommended as a revaprazan-loaded oral pharmaceutical alternative.

Silymarin-laden PVP-PEG polymeric composite for enhanced aqueous solubility and dissolution rate: Preparation and in vitro characterization

The aim of this work was to develop, optimize and characterize a silymarin-laden polyvinylpyrrolidone (PVP)-polyethylene glycol (PEG) polymeric composite to resolve low aqueous solubility and dissolution rate problem of the drug. A number of silymarin-laden polymeric formulations were fabricated with different quantities of PVP K-30 and PEG 6000 by the solvent-evaporation method. The effect of PVP K-30 and PEG 6000 on the aqueous solubility and dissolution rate was investigated. The optimized formulation and its constituents were characterized using powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) techniques. Both the PEG 6000 and PVP K-30 positively affected the aqueous solubility and dissolution rate of the drug. In particular, a formulation consisting of silymarin, PVP K-30 and PEG 6000 (0.25/1.5/1.5, w/w/w) furnished the highest solubility (24.39±2.95 mg/mL) and an excellent dissolution profile (~100% in 40 min). The solubility enhancement with this formulation was ~1150-fold as compared to plain silymarin powder. Moreover, all the constituents existed in the amorphous state in this silymarin-laden PVP-PEG polymeric composite. Accordingly, this formulation might be a promising tool to administer silymarin with an enhanced effect via the oral route.

Novel revaprazan-loaded gelatin microsphere with enhanced drug solubility and oral bioavailability

To develop a novel revaprazan-loaded gelatine microsphere with enhanced solubility and oral bioavailability, numerous gelatine microspheres were prepared using a spray-drying technique. The impact of gelatine amount on drug solubility in the gelatine microspheres was investigated. The physicochemical properties of the selected gelatine microsphere, such as shape, particle size and crystallinity, were evaluated. Moreover, its dissolution and pharmacokinetics in rats were assessed in comparison with revaprazan powder. Amongst the gelatine microspheres tested, the gelatine microsphere consisting of revaprazan and gelatine (1:2, w/w), which gave about 150-fold increased solubility, had the most enhanced drug solubility. It provided a spherical shape, amorphous drug and reduced particle size. Furthermore, it gave a higher dissolution rate and plasma concentration than did revaprazan powder. Particularly, it gave about 2.3-fold improved oral bioavailability in comparison with revaprazan powder. Therefore, this novel gelatine microsphere system is recommended as an oral pharmaceutical product of poorly water-soluble revaprazan.

Comparison of a revaprazan-loaded solid dispersion, solid SNEDDS and inclusion compound: Physicochemical characterisation and pharmacokinetics

The aim of this research was to compare three strategies for enhancing the solubility of poorly water-soluble revaprazan hydrochloride: solid dispersion, solid SNEDDS and inclusion compound. The influence of polymers, surfactants and oils on the drug solubility was assessed, and via the chosen carriers, the three types of formulations were prepared utilising spray drying technique. Their physicochemical properties, solubility, dissolution and pharmacokinetics in rats were performed compared with revaprazan powder. Among the liquid SNEDDS formulations assessed, the compositions of revaprazan, peceol, Tween 80 and Labrasol (10:15:55:30, weight ratio) provided the smallest emulsion size. Moreover, this liquid SNEDDS and dextran were suspended/dissolved in distilled water, and spray-dried, producing an optimal revaprazan-loaded solid SNEDDS. The appropriate solid dispersion and inclusion compound were composed of revaprazan, hydroxypropylmethylcellulose and cremophor A25 (5:1.4:5.6) and drug and hydroxyl-β-cyclodextrin (2.5:8.77), respectively. The crystalline drug was converted to an amorphous state in all formulations. In the solid dispersion, the drug was attached to the hydrophilic carrier. The solid SNEDDS and inclusion compound contained aggregate microspheres and separate microspheres, respectively. All formulations significantly increased the drug solubility, dissolution, plasma concentration and AUC compared with revaprazan powder. These properties were ranked in the order solid dispersion ≥ solid SNEDDS > inclusion compound. Particularly, the solid dispersion improved about 9500-fold drug solubility and 10-fold oral bioavailability. Thus, the improved properties were considerably dependent upon these techniques, although all of the techniques employed similar mechanisms. Among the strategies checked, the solid dispersion system would be recommended as an oral revaprazan-loaded pharmaceutical product.

A novel solid self-nanoemulsifying drug delivery system (S-SNEDDS) for improved stability and oral bioavailability of an oily drug, 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol

To develop a novel solid self-nanoemulsifying drug delivery system (S-SNEDDS) for a water-insoluble oily drug, 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) with improved stability and oral bioavailability, numerous S-SNEDDS were prepared with surfactant, hydrophilic polymer, antioxidant, and calcium silicate (porous carrier) using the spray-drying method. Their physicochemical properties were evaluated using emulsion droplet size analysis, SEM and PXRD. Moreover, the solubility, dissolution, stability, and pharmacokinetics of the selected S-SNEDDS were assessed compared with the drug and a commercial soft capsule. Sodium lauryl sulfate (SLS) and hydroxypropyl methylcellulose (HPMC) with the highest drug solubility were selected as surfactant and hydrophilic polymer, respectively. Among the antioxidants tested, only butylated hydroxyanisole (BHA) could completely protect the drug from oxidative degradation. The S-SNEDDS composed of PLAG/SLS/HPMC/BHA/calcium silicate at a weight ratio of 1: 0.25: 0.1: 0.0002: 0.5 provided an emulsion droplet size of less than 300 nm. In this S-SNEDDS, the drug and other ingredients might exist in the pores of carrier and attach onto its surface. It considerably improved the drug stability (about 100 vs. 70%, 60 °C for 5 d) and dissolution (about 80 vs. 20% in 60 min) compared to the commercial soft capsule. Moreover, the S-SNEDDS gave higher AUC, Cmax, and Tmax values than the commercial soft capsule; in particular, the former improved the oral bioavailability of PLAG by about 3-fold. Our results suggested that this S-SNEDDS provided excellent stability and oral bioavailability of PLAG. Thus, this S-SNEDDS would be recommended as a powerful oral drug delivery system for an oily drug, PLAG.