Optimization, characterization and in vitro/vivo evaluation of azilsartan nanocrystals

Central Composite Design Implemented Azilsartan Medoxomil Loaded Nanoemulsion to Improve Its Aqueous Solubility and Intestinal Permeability: In Vitro and Ex Vivo Evaluation

The present research attempted to design and develop a nanoemulsion formulation of azilsartan medoxomil to improve its aqueous solubility and intestinal permeability. Based on the solubility profile, ethyl oleate, tween 80, and Transcutol P were selected as the oil phase, surfactant, and co-surfactant, respectively. Central composite design (CCD) suggested an optimized azilsartan medoxomil- nanoemulsion formulation (optimized AZL-NE formulation) with 1.25% oil, 15.73% Smix, and 90 s ultrasonication time; it was found to have the droplet size, percentage transmittance, and % cumulative drug release (%CDR) of 71.5 nm, 93.46 ± 1.13%, and 90.14 ± 0.94%, respectively. Furthermore, it exhibited a 0.141 polydispersity index, 34.05 mV zeta potential, a 1.413 ± 0.03 refractive index, 6.68 ± 0.22 pH, 28.17 ± 0.52 cps viscosity, and a 96.98 ± 0.94% percentage drug content. Transmission electron microscopy (TEM) assessed the nano-sized spherical shape, and a differential scanning calorimeter (DSC) assessed the solubilization of the drug in the optimized formulation. The %CDR was 1.71 times higher and the % cumulative drug permeation was 2.1 times higher for the optimized AZL-NE formulation than for the drug suspension through an intestinal segment of a rat, which was also supported by confocal laser scanning microscopy (CLSM) studies. Thus, the nanoemulsion formulation of azilsartan medoxomil ensured the enhancement of the drug availability in the body.

Azilsartan-nicotinamide cocrystal: Preparation, characterization and in vitro / vivo evaluation

Azilsartan (AZL) is an angiotensin II receptor antagonist, which is mainly used for the treatment of hypertension. AZL has the advantages of high selectivity, hypotensive effect, protection of cardiovascular and cerebrovascular diseases. In order to improve the water solubility of AZL and its bioavailability, AZL -nicotinamide (NA) cocrystal was prepared by mechanical ball milling, and the effect of ball milling conditions on cocrystal preparation were studied. AZL-NA cocrystal was identified and characterized by powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy and Fourier transform infrared spectrometry. The results showed that AZL-NA cocrystal with the molar ratio of 1:2 was successfully prepared. And the optimum ball milling condition was milling speed of 300 rpm, milling time of 50 min, the solvent was ethanol/acetonitrile (1:1, v/v), and the solvent dosage (η) was 0.8 μL/mg. The results of solubility tests showed that the solubility of AZL in the cocrystal was 3.39 times higher than the pure drug at 24 h. And the results of vitro dissolution tests showed that the cumulative dissolution of AZL in 2 h was about 10%. While distilled water, pH 1.2 and pH 4.5 acid or buffered solutions and pH 6.8 buffer phosphate salt solution was used as the dissolution medium, the cumulative dissolution of AZL in cocrystal reached 50%, 35%, 55% and 90%, respectively, showing obvious improvement of dissolution. In addition, the accelerated stability tests showed that the AZL-NA cocrystal had good chemical stability. And the pharmacokinetic results showed that AZL-NA cocrystal could significantly improve the bioavailability of AZL.

Design of ultra-fine carvedilol nanococrystals: Development of a safe and stable injectable formulation

Carvedilol (CAR) is a strategic beta-blocker agent which its application has been limited by its very low water solubility. The present study describes a soluble form of drug based on nano-cocrystal (NCC) anti-solvent precipitation technique. The COSMOquick software was employed to select the optimum coformer (tartaric acid, TA) and organic solvent (acetone) relying on the enthalpy changes of cocrystallization and solubilization. Central Composite Design (CCD) considering the impact of CAR, TA, poloxamer 188 (stabilizer) concentrations, and anti-solvent/solvent ratio on CAR NCCs particle size (PS) could produce ultra-fine NCCs (about 1 nm). The lyophilization of NCCs investigating slow/fast freezing rates, various types and concentrations of cryprotectants and lyoprotectants indicated that PEG and trehalose (5 % w/vconcentration) under slow freezing rate could re-produce the initial PSs successfully. CAR NCCs indicated about 2000 fold increase in solubility compared with pure CAR. DSC and PXRD experiments proved that the formulations containing trehalose led to more crystalline and the ones comprising PEG led to more amorphous structures. Interestingly, the slow freezed PEG protected NCCs were physically stable for at least 18 months. In conclusion, the NCC technology could produce the first safe soluble form of CAR for treating hypertension urgencies easy for industrial scale-up.

Delivery strategies of amphotericin B for invasive fungal infections

Invasive fungal infections (IFIs) represent a growing public concern for clinicians to manage in many medical settings, with substantial associated morbidities and mortalities. Among many current therapeutic options for the treatment of IFIs, amphotericin B (AmB) is the most frequently used drug. AmB is considered as a first-line drug in the clinic that has strong antifungal activity and less resistance. In this review, we summarized the most promising research efforts on nanocarriers for AmB delivery and highlighted their efficacy and safety for treating IFIs. We have also discussed the mechanism of actions of AmB, rationale for treating IFIs, and recent advances in formulating AmB for clinical use. Finally, this review discusses some practical considerations and provides recommendations for future studies in applying AmB for combating IFIs.

Diclofenac-proline nano-co-crystal development, characterization, in vitro dissolution and diffusion study

Nanotechnology has been widely developed to improve the solubility of active pharmaceutical ingredients. Co-crystal discovery has also taken much attention in drug design and development. A combination of the two techniques generates “nano-co-crystallization”, a new approach to obtaining the superior character of drugs. Previously, a new diclofenac-proline co-crystal (DPC) arrangement has been reported. The present research attempted to develop a nano-diclofenac-proline-co-crystal (NDPC) and to evaluate its formation kinetics, and dissolution-diffusion improvements. Both top-down and bottom-up methods optimized nano-co-crystal production. The top-down technique was used through the wet milling procedure and neat grinding procedures, while the bottom-up technique was performed through the globule inversion phase and fast evaporation assisted microwaving. The NDPCs obtained were then characterized by dynamic light scattering, binocular microscope, scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry, powder x-ray diffractometry, and Fourier transform infrared spectrophotometry. The kinetics of NDPC formation was determined based on the difference of microwaving versus the co-crystal yield, which was analyzed using Fourier transform infrared spectroscopy. Dissolution was tested by type 2 apparatus, and diffusion was tested using Franz diffusion cells. The bottom-up method by fast evaporation assisted microwaving provided the best nano-co-crystal with a mean diameter of 598.2 ± 63.2 nm and a polydispersity index of 0.278 ± 0.062. Nano-co-crystal formation kinetic, which was evaluated by FTIR, indicated to follow first order. Finally, NDPC showed the superior dissolution and diffusion profile than conventional-DPC. In this study, we demonstrate a promising alternative for improving the dissolution and diffusion of the drug by nano-co-crystallization.

Solubility of Azilsartan in Methanol, Ethanol, Acetonitrile, n-Propanol, Isopropanol, Tetrahydrofuran, and Binary Solvent Mixtures between 293.15 and 333.15 K

A precise determination method of azilsartan solubility between 293.15 and 333.15 K in several ordinary solvents and some of their aqueous mixtures was established by high-performance liquid chromatography. In all tested solvents, its solubility shows exponential growth with the increase in temperature. This trend is especially pronounced in methanol and ethanol. The order of solubility of azilsartan can be expressed as ethanol > tetrahydrofuran > ethanol/water (8/2, v/v) > methanol > methanol/water (8/2, v/v) > n-propanol > isopropanol > ethanol/Water (5/5, v/v) > acetonitrile. The solubility data of azilsartan were well correlated by the λh model. Moreover, the thermodynamic data including the dissolving enthalpy, entropy, and Gibbs free energy of azilsartan in each solvent were calculated which is crucial to its preparation technology study.

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.

Hybrid drug nanocrystals

Nanocrystals show promise to deliver poorly water-soluble drugs to yield systemic exposure. However, our knowledge regarding the in vivo fate of nanocrystals is in its infancy, as nanocrystallization is simply viewed as an approach to enhance the dissolution of drug crystals. The dying crystal phenomenon inspired the development of hybrid nanocrystals by physically embedding fluorophores into the crystal lattice. This approach achieved concurrent therapy and bioimaging and is well-established to study pharmacokinetics and nanocrystal dissolution in vivo. Nanocrystals also offer the advantage of long-term durability in the body for interacting with biological tissues and cells. This review introduces the hybrid nanocrystal technique, including the theoretical concepts, preparation, and applications. We also discuss the latest development in self-discriminative hybrid nanocrystals utilizing environment-responsive probes. This review will stimulate further development and application of nanocrystal-based drug delivery systems for theranostic strategies.

Formulation and evaluation of docetaxel nanosuspensions: In-vitro evaluation and cytotoxicity

OBJECTIVE

The aim of the present study was to formulate the anticancer drug; docetaxel (DOX) as nanoparticles to enhance its biological activity.

METHODOLOGY

Solvent precipitation method was used to prepare DOX-loaded nanoparticles and was stabilized by different concentrations of hydroxypropyl methylcellulose (HPMC, E5) and sodium deoxycholate (SDC).

RESULTS

The results showed that the particle size of the prepared DOX nanoparticles stabilized by SDC was small in comparison to those stabilized by the corresponding HPMC concentrations. The smallest particle size (83.97 nm) was obtained by using SDC as stabilizer at 5% level with zeta potential of -13.6 mV. It was concluded that increasing the stabilizer concentration resulted in increase in both initial and overall cumulative drug release. The release rate in case of nanoparticles stabilized by 5% SDC was 33% and 87% after 1 and 24 h respectively. The results showed that a significant reduction in the viability of FRO cells was observed at all tested time intervals in case of nanoparticles stabilized by 5% SDC at concentrations of 100 and 1000 μM/ml. In contrast, no signs of cytotoxicity was observed for nanoparticles stabilized by 5% HPMC at 10 and 100 μM/ml concentrations.

First-time oral administration of resveratrol-loaded layer-by-layer nanoparticles to rats – a pharmacokinetics study

trans-Resveratrol (RSV) is a plant-derived polyphenol endowed with a broad spectrum of promising therapeutic activities.