Sugar coated ceramic nanocarriers for the oral delivery of hydrophobic drugs: formulation, optimization and evaluation

In order to enhance the delivery of poorly-soluble drugs, we have explored aquasomes (three-layered, ceramic core based, oligosaccharide coated nanoparticles) as potential carriers for the delivery of model hydrophobic drug piroxicam (log P = 3.1). Ceramic nanoparticles were prepared using two techniques; namely, co-precipitation by refluxing and co-precipitation by sonication. Core preparation was finally done using sonication approach; based on the higher % yield (42.4 ± 0.4%) and shorter duration (1 day) compared to the reflux method (27.4 ± 2.05%, 6 days). Lactose loading onto ceramic core was achieved using adsorption. Colorimetric analysis of lactose coating was done using Anthrone method. Optimization of process variables namely, incubation time and core to coat ratio (for sugar loading) was carried out. Optimum time of incubation was 3 h and the core to coat ratio was 4:1. The drug loading was achieved by incubating the sugar loaded cores in different concentrations of piroxicam solution and it was found that 1.5% w/v piroxicam was optimal. Structural characterization using Fourier-Transform Infra Red Spectroscopy (FTIR) confirmed the presence of sugar coating onto the core. Morphological evaluation using transmission electron microscopy (TEM) revealed spherical nanoparticles (size 56.56 ± 5.93 nm for lactose coated core and 184.75 ± 13.78 nm for piroxicam loaded aquasomes) confirming the nanometric dimensions.     

Tolmetin sodium-loaded thermosensitive mucoadhesive liquid suppositories for rectal delivery; strategy to overcome oral delivery drawbacks

Tolmetin sodium (TS) is a nonsteroidal anti-inflammatory drug (NSAID) indicated for treatment of musculoskeletal issues. As other NSAID, TS displays a marked side effects on the gastro-intestinal (GI) tract after oral administration. Traditional solid suppositories can cause pain and discomfort for patients, may reach the end of the colon; consequently, the drug can undergo the first-pass effect. TS liquid suppository (TS-_LS) was developed to enhance patient compliance and rectal mucosal safety in high-risk patients receiving highly NSAID therapy. This work was conducted to optimize and evaluate Poloxamer P407/P188-based thermoresponsive TS-_LS by using mucoadhesive polymers such as methylcellulose (MC). TS-_LS was prepared by cold method and characterized their in vitro physicochemical properties as gelation temperature (GT), gel strength, bioadhesive properties, and in vitro release. The safety of the prepared suppository on rectum, stomach, and liver was evaluated histologically. Pharmacokinetic analyses were performed to compare rectal TS-_LS to orally Rhumtol^® capsules. The results showed that the optimized TS-_LS; composed of P407/P188/MC (21/9/0.5% w/w) displayed gelation at rectum temperature ～32.90?°C, gel strength of 21.35?s and rectal retention force at the administration site of 24.25?×?10²?dyne/cm². Moreover, TS-_LS did not cause any morphological damage to the rectal tissues. Pharmacokinetic parameters of optimized TS-_LS formulation revealed 4.6 fold increase in bioavailability as compared to Rhumtol^® capsules. Taken together, the results demonstrated that liquid suppository is a potential and physically safe rectal delivery carrier for improvement rectal bioavailability and in vivo safety of TS.     

Dual delivery of hydrophilic and hydrophobic drugs from chitosan/diatomaceous earth composite membranes

Oral administration of drugs presents important limitations, which are frequently not granted the importance that they really have. For instance, hepatic metabolism means an important drug loss, while some patients have their ability to swell highly compromised (i.e. unconsciousness, cancer…). Sublingual placement of an accurate Pharmaceutical Dosage Form is an attractive alternative. This work explores the use of the β-chitosan membranes, from marine industry residues, composed with marine sediments for dual sublingual drug delivery. As proof of concept, the membranes were loaded with a hydrophilic (gentamicin) and a hydrophobic (dexamethasone) drug. The physico-chemical and morphological characterization indicated the successful incorporated of diatomaceous earth within the chitosan membranes. Drug delivery studies showed the potential of all formulations for the immediate release of hydrophilic drugs, while diatomaceous earth improved the loading and release of the hydrophobic drug. These results highlight the interest of the herein developed membranes for dual drug delivery.

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A facile lanthanum-doping strategy for enhancing the long-cycle performance of lithium-rich layered oxides

Journal of Materials Science: Materials in Electronics - By virtue of high discharge capacity and wide voltage range, lithium-rich layered oxides (LLO) are expected to become the most promising...     

Preparation of hydrophobic drugs cyclodextrin complex by lyophilization monophase solution

A novel method was evaluated for preparation of hydrophobic drugs cyclodextrin (CD) complex in this study. To obtain sterilized drug-CD complex lyophilized powder for injection or other purpose, the CD solution in water and the hydrophobic drug in tertiary butyl alcohol (TBA) were mixed in a suitable volume ratio, filtered through 0.22 μm millpores, and subsequently freeze-dried. A high drug concentration was obtained in the co-solvent due to the good solvency of TBA, which is miscible with water in any proportion, for hydrophobic drugs. Moreover, TBA could be removed rapidly and completely by freeze-drying because of its high vapor pressure and high melting point. The chemical stability of some labile active compounds was also improved in TBA-water co-solvent. Based on the data from differential scanning calormetry (DSC) and X-ray diffractometry (XRD), drug was amorphous in freeze-dried complex. The fourier transform infrared spectra indicated drug-CD interaction was present in drug-CD complex. An enhanced dissolution rate was also obtained in drug-CD complex. These results proved drug-CD complex had been formed after this technique. Thus, this report provided a simple, efficient, and economic technique for preparation of hydrophobic drugs CD complex, which may be useful practically in modifying hydrophobic drugs physicochemical properties and improving their absorption and pharmacodynamics.     

PLA-PEG-PLA copolymer-based polymersomes as nanocarriers for delivery of hydrophilic and hydrophobic drugs: preparation and evaluation with atorvastatin and lisinopril

Tri-block poly(lactide)–poly(ethylene glycol)–poly(lactide) (PLA–PEG–PLA) copolymers were synthesized and used to prepare polymersomes loaded separately by the hydrophobic and hydrophilic model drugs, atorvastatin and lisinopril, respectively. The resulting nanostructures were characterized by various techniques such as FTIR, DSC, PCS and AFM. The polymersomes exhibited high encapsulation efficiencies of almost 78% and 70.8% for atorvastatin and lisinopril, respectively. Investigation on FTIR and DSC results revealed that such a high encapsulation efficiency is due to strong interaction between atorvastatin and the copolymer. The impact of drug/copolymer ratio and copolymer composition on drug-loading efficiency and drug release behavior were also studied. The results showed that in case of lisinopril, polymersomes exhibited a triphasic drug release, while for atorvastatin a biphasic release profile was obtained. Overall, the results indicated that PLA–PEG–PLA polymersomes can be considered as a promising carrier for both hydrophilic and hydrophobic drugs.     

Functionalized nanoscale oil bodies for targeted delivery of a hydrophobic drug

Effective formulations of hydrophobic drugs for cancer therapies are challenging. To address this issue, we have sought to nanoscale artificial oil bodies (NOBs) as an alternative. NOBs are lipid-based particles which consist of a central oil space surrounded by a monolayer of oleosin (Ole)-embedded phospholipids (PLs). Ole was first fused with the anti-HER2/neu affibody (Ole-ZH2), and the resulting hybrid protein was overproduced in Escherichia coli. ZH2-displayed NOBs were then assembled by sonicating the mixture containing plant oil, PLs, and isolated Ole-ZH2 in one step. To illustrate their usefulness, functionalized NOBs were employed to encapsulate a hydrophobic anticancer drug, Camptothecin (CPT). As a result, these CPT-loaded NOBs remained stable in serum and the release of CPT at the non-permissive condition exhibited a sustained and prolonged profile. Moreover, plain NOBs were biocompatible whereas CPT-loaded NOBs exerted a strong cytotoxic effect on HER2/neu-positive cells in vitro. Administration of xenograft nude mice with CPT-loaded NOBs also led to the regression of solid tumors in an effective way. Overall, the result indicates the potential of NOBs for targeted delivery of hydrophobic drugs.     

Polyelectrolyte microcapsules for sustained delivery of water-soluble drugs

Polyelectrolyte capsules composed of weak polyelectrolytes are introduced as a simple and efficient system for spontaneous encapsulation of low molecular weight water-soluble drugs. Polyelectrolyte capsules were prepared by layer-by-layer (LbL) assembling of weak polyelectrolytes, poly(allylamine hydrochloride) (PAH) and poly(methacrylic acid) (PMA) on polystyrene sulfonate (PSS) doped CaCO₃ particles followed by core removal with ethylene-diaminetetraacetic acid (EDTA). The loading process was observed by confocal laser scanning microscopy (CLSM) using tetramethylrhodamineisothiocyanate labeled dextran (TRITC-dextran) as a fluorescent probe. The intensity of fluorescent probe inside the capsule decreased with increase in cross-linking time. Ciprofloxacin hydrochloride (a model water-soluble drug) was spontaneously deposited into PAH/PMA capsules and their morphological changes were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The quantitative study of drug loading was also elucidated which showed that drug loading increased with initial drug concentration, but decreased with increase in pH. The loaded drug was released in a sustained manner for 6 h, which could be further extended by cross-linking the capsule wall. The released drug showed significant antibacterial activity against E. coli. These findings indicate that such capsules can be potential carriers for water-soluble drugs in sustained/controlled drug delivery applications.     

A facile synthesis strategy for structural property control of mesoporous alumina and its effect on catalysis for biodiesel production

A facile synthesis route for the production of mesoporous alumina (MA) with tuneable structural properties including BET surface area, pore volume and pore size was systematically investigated by tailoring the amount of template P123 used in the synthesis. The general synthesis strategy was based on a sol–gel process by hydrolysis of aluminium isopropoxide associated with nonionic block copolymer (P123) as the template in a water system. The results showed that the addition of P123 played a crucial role in the synthesis process, leading to very regular variations in the surface area (146.6–261.6 m²/g), pore volume (0.164–2.152 cm³/g) and pore size (3.5–29.9 nm). MA-supported K species (MA-K) were prepared using KNO₃ as the potassium precursor and adopted as the catalysts for biodiesel production. The introduction of K species to MA caused a reduction in the BET surface area and pore volume, but gave rise to a significant increase in pore size, especially when the K species was higher than 10%. K incorporation resulted in the formation of disordered, but significantly larger mesopores. In catalysis, by introducing 20% molar fraction of K species to MA, very high yield of biodiesel was achieved (92.2%) and further increased to 94.4% with 25% K. Based on the control of structural properties of MA, a series of MA-20K catalysts with the same K loading (20%) but different structural properties were prepared by varying P123 addition and were further tested in biodiesel synthesis. Higher biodiesel yields were obtained over the MAs with higher surface area, pore volume and bigger pore size, which were attributed to the reduced mass transfer limitation in catalysis.     

Development of self-microemulsifying drug delivery system for oral delivery of poorly water-soluble nutraceuticals

The objective of the study was to develop a self-microemulsifying drug delivery system (SMEDDS), also known as microemulsion preconcentrate, for oral delivery of five poorly water-soluble nutraceuticals or bioactive agents, namely, vitamin A, vitamin K2, coenzyme Q₁₀, quercetin and trans-resveratrol. The SMEDDS contained a 1:1 mixture (w/w) of Capmul MCM NF (a medium chain monoglyceride) and Captex 355 EP/NF (a medium chain triglyceride) as the hydrophobic lipid and Tween 80 (polysorbate 80) as the hydrophilic surfactant. The lipid and surfactant were mixed at 50:50 w/w ratio. All three of the SMEDDS components have GRAS or safe food additive status. The solubility of nutraceuticals was determined in Capmul MCM, Captex 355, Tween 80, and the SMEDDS (microemulsion preconcentrate mixture). The solubility values of vitamin A palmitate, vitamin K2, coenzyme Q₁₀, quercetin, and trans-resveratrol per g of SMEDDS were, respectively, 500, 12, 8, 56, and 87?mg. Appropriate formulations of nutraceuticals were prepared and filled into hard gelatin capsules. They were then subjected to in vitro dispersion testing using 250?mL of 0.01 N HCl in USP dissolution apparatus II. The dispersion test showed that all SMEDDS containing nutraceuticals dispersed spontaneously to form microemulsions after disintegration of capsule shells with globule size in the range of 25 to 200?nm. From all formulations, except that of vitamin K2, >80–90% nutraceuticals dispersed in 5–10?min and there was no precipitation of compounds during the test period of 120?min. Some variation in dispersion of vitamin K2 was observed due to the nature of the material used (vitamin K2 pre-adsorbed onto calcium phosphate). The present report provides a simple and organic cosolvent-free lipid-based SMEDDS for the oral delivery of poorly water-soluble nutraceuticals. Although a 50:50 w/w mixture of lipid to surfactant was used, the lipid content may be increased to 70:30 without compromising the formation of microemulsion.     

Bioerodible polymeric nanoparticles for targeted delivery of proteic drugs

Significant efforts are being devoted to develop nanotechnology for drug delivery, mainly because of the distinct advantages offered by nanometer-size polymeric systems. Moreover, targeted drug delivery can be obtained by polymer conjugation to biospecific ligands. The present investigation was aimed mainly at determining the targeting ability of hybrid nanoparticles based on synthetic polymer/protein hybrid matrices. These nanoparticles were designed for liver targeted release of proteic drugs with antiviral activity, such as alpha-interferon. Human serum albumin and the monoesters of alternating copolymers of maleic anhydride/alkyl vinyl ethers of oligo(ethylene glycol) were selected as proteic and synthetic components, respectively. Digalactosyl diacyl glycerol, a natural glycolipid selectively recognized by the asialofetuin receptor present on liver hepatocytes was used as active targeting agent. Nanoparticles of 100-300 nm average size were obtained by controlled coprecipitation method. Investigation of nanoparticle surface properties by spectroscopic analysis and by biological tests indicated that the synthesized nanoparticles do expose on their surface targeting moieties that selectively interact with liver hepatocytes receptors.     

Lipid nanocapsules for intracellular drug delivery of anticancer drugs

As non-phagocytic eukaryotic cells can internalize particles < 1 microm in size, small size (25 to 110 nm) lipid nanocapsules (LNC) are proposed for the intracellular drug delivery of anticancer drugs to cancer cells. LNC of different diameters were loaded with etoposide or paclitaxel and subsequently tested for drug release kinetics and their efficiency to reduce cancer cell growth in cell culture. Relative high drug loads could be achieved and sustained drug release can be provided over a period of several days (etoposide) up to a few weeks (paclitaxel). While particle size exhibited only minor influences on the release kinetics, higher initial drug load led to a distinctly lower burst release. In a cancer cell culture model, etoposide or paclitaxel LNC showed a 4-fold or 40-fold higher efficiency, respectively than the drug solution while blank LNC were found to be less toxic than the pure drug at equivalent concentrations. The uptake and intracellular accumulation of LNC was confirmed by confocal laser scanning microscopy after fluorescence labeling of the nanocarriers. This nanoparticulate system is able to achieve efficient intracellular drug concentrations and seems to be therefore a promising therapeutic approach in cancer treatment.     

Nanocrystals for the parenteral delivery of poorly water-soluble drugs

Nanocrystals have drawn increasing interest in pharmaceutical industry because of the ability to improve dissolution of poorly water-soluble drugs. Nanocrystals can be produced by top-down and bottom-up technologies and have been explored for a variety of therapeutic applications. Here we review the methods of nanocrystal production and parenteral applications of nanocrystals. We also discuss remaining challenges in the development of nanocrystal products.     

Cuboidal lipid polymer nanoparticles of rosuvastatin for oral delivery

The present work aimed to develop and characterize sustained release cuboidal lipid polymeric nanoparticles (LPN) of rosuvastatin calcium (ROS) by solvent emulsification-evaporation process. A three factor, two level (2³) full-factorial design was applied to study the effect of independent variables, i.e. amount of lipid, surfactant and polymer on dependent variables, i.e. percent entrapment efficiency and particle size. Optimized formulations were further studied for zeta potential, TEM, in vitro drug release and ex vivo intestinal permeability. Cuboidal nanoparticles exhibited average particle size 61.37?±?3.95?nm, entrapment efficiency 86.77?±?1.27% and zeta potential ?6.72?±?3.25?mV. Nanoparticles were lyophilized to improve physical stability and obtain free-flowing powder. Effect of type and concentration of cryoprotectant required to lyophilize nanoparticles was optimized using freeze-thaw cycles. Mannitol as cryoprotectant in concentration of 5-8% w/v was found to be optimal providing zeta potential ?20.4?±?4.63?mV. Lyophilized nanoparticles were characterized using FTIR, DSC, XRD and SEM. Absence of C=C and C–F aromatic stretch at 1548 and 1197?cm^?1, respectively, in LPN indicated coating of drug by lipid and polymer. In vitro diffusion of ROS using dialysis bag showed pH-independent sustained release of ROS from LPN in comparison to drug suspension. Intestinal permeability by non-everted gut sac model showed prolonged release of ROS from LPN owing to adhesion of polymer to mucus layer. In vivo absorption of ROS from LPN resulted in 3.95-fold increase in AUC_0–last and 7.87-fold increase in mean residence time compared to drug suspension. Furthermore modified tyloxapol-induced rat model demonstrated the potential of ROS-loaded LPN in reducing elevated lipid profile.     

Synthesis of biomolecule-modified mesoporous silica nanoparticles for targeted hydrophobic drug delivery to cancer cells

Synthetic methodologies integrating hydrophobic drug delivery and biomolecular targeting with mesoporous silica nanoparticles are described. Transferrin and cyclic-RGD peptides are covalently attached to the nanoparticles utilizing different techniques and provide selectivity between primary and metastatic cancer cells. The increase in cellular uptake of the targeted particles is examined using fluorescence microscopy and flow cytometry. Transferrin-modified silica nanoparticles display enhancement in particle uptake by Panc-1 cancer cells over that of normal HFF cells. The endocytotic pathway for these particles is further investigated through plasmid transfection of the transferrin receptor into the normal HFF cell line, which results in an increase in particle endocytosis as compared to unmodified HFF cells. By designing and attaching a synthetic cyclic-RGD, selectivity between primary cancer cells (BT-549) and metastatic cancer cells (MDA-MB 435) is achieved with enhanced particle uptake by the metastatic cancer cell line. Incorporation of the hydrophobic drug Camptothecin into these two types of biomolecular-targeted nanoparticles causes an increase in mortality of the targeted cancer cells compared to that caused by both the free drug and nontargeted particles. These results demonstrate successful biomolecular-targeted hydrophobic drug delivery carriers that selectively target specific cancer cells and result in enhanced drug delivery and cell mortality.     

Comparison of two polymeric carrier formulations for controlled release of hydrophilic and hydrophobic drugs

Two temperature sensitive drug carriers, poly (N-isopropylacrylamide-co-acrylic acid) (PNIPA-co-AA) and poly (N-isopropylacrylamide-vinyl pyrrolidone-acrylic acid) (PNIPA-VP-AA), were successfully synthesized through free radical mechanism. The diameters of PNIPA-co-AA and PNIPA-VP-AA particles can be regulated to be less than 100 nm, which were related to surfactant sodiumdodecyl sulfate and initiator ferrous ammonium sulfate, respectively. The lower critical solution temperature (LCST) of them can be manipulated to be higher than 40 °C, which was correlated to amount of acrylic acid (AA) that was copolymerized with NIPA. Hydrophilic anti-tumor drugs, 5-fluorouracil (5-Fu) and hydrophobic drug thalidomide were entrapped into PNIPA-co-AA and PNIPA-VP-AA, respectively. For different interaction mechanism between drug and carrier, 5-Fu was prone to be entrapped in PNIPA-co-AA with loading efficiency larger than 10% (w/w), while thalidomide was entrapped in PNIPA-VP-AA up to 80% (w/w). Fluorescein, an angiography agent, was used to evaluate the drug loading mechanism between PNIPA-VP-AA and poor water-soluble drug. In vitro drug release behavior from these two drug carriers were significantly different and showed temperature dependent, which demonstrated that PNIPA-co-AA and PNIPA-VP-AA are promising candidates for different controlled drug delivery system.     

Critical evaluation of permeation enhancers for oral mucosal drug delivery

Background: Drug delivery via oral mucosa is an alternative method of systemic administration for various classes of therapeutic agents. Among the oral mucosae, buccal and sublingual mucosae are the primary focus for drug delivery. Buccal delivery offers a clear advantage over the peroral route by avoidance of intestinal and hepatic first-pass metabolism. However, despite offering the possibility of improved systemic drug delivery, buccal administration has been utilized for relatively few pharmaceutical products so far. One of the major limitations associated with buccal delivery is low permeation of therapeutic agents across the mucosa. Various substances have been explored as permeation enhancers to increase the flux/absorption of drugs through the mucosa, but irritation, membrane damage, and toxicity are always associated with them and limit their use. A clinically accepted permeation enhancer must increase membrane permeability without causing toxicity and permanent membrane damage. To date, the information available on oral mucosal permeation enhancement is much less than transdermal enhancement, though oral mucosa is more resistant to damage than other mucosal membranes. This article reviews the various categories of permeation enhancers for oral mucosal drug delivery, their mechanism of action, their usefulness, and the limitations associated with their use. Conclusion: To optimize the concentration of enhancer to limit its toxicity while facilitating an enhancing effect reproducibly will be a big challenge for future developments. Advances in permeability modulation and formulation with appropriate enhancers can provide for effective and feasible buccal drug delivery for many drugs, which otherwise have to be injected or ingested with water.