Self-assembled nanonization of fatty acid-conjugated vaccine antigen for enhanced thermal stability

The aim of this study was to evaluate the enhanced thermal stability and physicochemical properties of fattigated vaccine antigens. High molecular weight influenza hemagglutinin (Heg) was used as a model antigen because of low heat stability requiring cold chamber. Heg was conjugated with long-chain oleic acid (C18) and short-chain 3-decenoic acid (C10) to prepare fattigated Heg. Circular dichroism analysis revealed no significant changes in the three-dimensional structure post-conjugation. In the liquid state, the fattigated Heg was self-assembled into nanoparticles (NPs) due to its amphiphilic nature, with sizes of 136.27 ± 12.78 nm for oleic acid-conjugated Heg (HOC) and 88.73 ± 3.27 nm for 3-decenoic acid-conjugated Heg (HDC). Accelerated thermal stability studies at 60 °C for 7 days demonstrated that fattigated Heg exhibited higher thermal stability than Heg in various liquid or solid states. The longer-chained HOC showed better thermal stability than HDC in the liquid state, attributed to increased hydrophobic interactions during self-assembly. In bio-mimicking liquid states at 37 °C, HOC exhibited higher thermal stability than Heg. Furthermore, solid-state HOC with cryoprotectants (trehalose, mannitol, and Tween® 80) had significantly increased thermal stability due to reduced exposure of protein surface area via nanonization behavior. The current fattigation platform could be a promising strategy for developing thermostable nano vaccines of heat-labile vaccine antigens.

Nanonization and Deformable Behavior of Fattigated Peptide Drug in Mucoadhesive Buccal Films

This study was tasked with the design of mucoadhesive buccal films (MBFs) containing a peptide drug, leuprolide (LEU), or its diverse nanoparticles (NPs), for enhanced membrane permeability via self-assembled nanonization and deformable behavior. An LEU-oleic acid conjugate (LOC) and its self-assembled NPs (LON) were developed. Additionally, a deformable variant of LON (d-LON) was originally developed by incorporating l-α-phosphatidylcholine into LON as an edge activator. The physicochemical properties of LON and d-LON, encompassing particle size, zeta potential, and deformability index (DI), were evaluated. MBFs containing LEU, LOC, and NPs (LON, d-LON) were prepared using the solvent casting method by varying the ratio of Eudragit RLPO and hydroxypropyl methylcellulose, with propylene glycol used as a plasticizer. The optimization of MBF formulations was based on their physicochemical properties, including in vitro residence time, dissolution, and permeability. The dissolution results demonstrated that the conjugation of oleic acid to LEU exhibited a more sustained LEU release pattern by cleaving the ester bond of the conjugate, as compared to the native LEU, with reduced variability. Moreover, the LOC and its self-assembled NPs (LON, d-LON), equivalent to 1 mg LEU doses in MBF, exhibited an amorphous state and demonstrated better permeability through the nanonization process than LEU alone, regardless of membrane types. The incorporation of lauroyl-L-carnitine into the films as a permeation enhancer synergistically augmented drug permeability. Most importantly, the d-LON-loaded buccal films showed the highest permeability, due to the deformability of NPs. Overall, MBF-containing peptide NPs and permeation enhancers have the potential to replace parenteral LEU administration by improving LEU druggability and patient compliance.

Polyelectrolyte-based solid dispersions for enhanced dissolution and pH-Independent controlled release of sildenafil citrate

The aim of this study was to design a novel matrix tablet with enhanced dissolution and pH-independent controlled release of sildenafil citrate (SIL), a drug with pH-dependent solubility, by using solid dispersions (SDs) and polyelectrostatic interactions. SIL-loaded SDs were prepared using various polymeric carriers such as poloxamer 188, poloxamer 407, Soluplus®, polyvinylpyrrolidone (PVP) K 12, and PVP K 17 by the solvent evaporation method. Among these polymers, Soluplus® was found to be the most effective in SDs for enhancing the drug dissolution over 6 h in pH 6.8 intestinal fluid. SIL was well dispersed in Soluplus®-based SDs in an amorphous form. When the Soluplus®-based SDs were added in the tablet containing positively charged chitosan and negatively charged Eudragit® L100, the drug release rate was further modulated in a controlled manner. The charge density of the tablet was higher at pH 6.8 than at pH 1.2 due to the polyelectrostatic interaction between chitosan and Eudragit® L100. This interaction could provide a pH-independent controlled release of SIL. Our study demonstrates that a combinatory approach of Soluplus®-based SDs and polyelectrostatic interactions can improve the dissolution and pH-independent release performance of SIL. This approach could be a promising pharmaceutical strategy to design a matrix tablet of poorly water-soluble drugs for the enhanced bioavailability.

Roles of Fatty Acid Chain Length and Enzyme-Oriented Drug Controlled Release from pH-Triggering Self-Assembled Fatty Acid Conjugated Quetiapine Nanosuspensions

Background

Quetiapine (QTP) is a first-line antipsychotic drug, but its therapeutic druggability and patient adherence were limited due to high oral dose strength, low bioavailability and physicochemical/biopharmaceutical issues.

Purpose

To investigate the roles of fatty acid chain length and enzyme-oriented QTP controlled release from pH-triggering self-assembled fatty acid conjugated QTP nanosuspensions (NSPs).

Methods

QTP was conjugated with different chain length fatty acids (C10-decanoic acid, C14-myristic acid, C18-stearic acid) to obtain QTP-fatty acid conjugates (QFCs: QD, QM, QS) by exploiting 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/4-dimethylaminopyridine (EDC/DMAP) conjugation chemistry. Then, the solubility, partitioning coefficient (log P), cell viability and cleavage kinetics of QFCs were evaluated. The pH-triggering self-assembled behaviors of QFCs to form QTP-fatty acid NSPs (QDN, QMN, QSN) by varying pH, QFC concentration and proton-to-QTP ratios were characterized. The morphological images, critical micelle concentration (CMC), physicochemical properties and enzyme-oriented QTP controlled release of NSPs were examined.

Results

Three QFCs were synthesized with different chain length fatty acids from QTP after desalting fumarate from QTP fumarate. The pH, QFC concentration and proton-to-quetiapine molar ratio could influence physicochemical properties and nanonization behaviors of QFCs. All three QFCs showed no effect on the viability of myoblast cells. The pH-triggering self-assembly of amphiphilic QFCs to form nanoparticles (NPs) occurred as the amine moiety of QTP was readily ionized in a strongly acidic environment (pH 1.2). Interestingly, the longer the fatty acid chain length, the lower water solubility, the higher log P (lipophilicity) and the smaller NP particle size were observed. The conversion rate of QFCs to liberate QTP by esterase in human plasma and liver S9 fractions was also inversely proportional to the fatty acid carbon chain length. Interestingly, the freeze-dried QMN showed the esterase-oriented controlled release of QTP over one month, unlike the initial burst release of QDN or the slowly delayed release pattern of QSN.

Conclusion

A new pH-triggering self-assembled nanonization platform was developed using different chain length fatty acid conjugated QTP in low pH environment. By varying fatty acid chain length, the enzyme-oriented QTP controlled release dosage form was challenged to enhance the therapeutic effectiveness of QTP.

Cellular Efficacy of Fattigated Nanoparticles and Real-Time ROS Occurrence Using Microfluidic Hepatocarcinoma Chip System: Effect of Anticancer Drug Solubility and Shear Stress

The objective of this study was to evaluate the effectiveness of organ-on-chip system investigating simultaneous cellular efficacy and real-time reactive oxygen species (ROS) occurrence of anticancer drug-loaded nanoparticles (NPs) using hepatocarcinoma cells (HepG2) chip system under static and hepatomimicking shear stress conditions (5 dyne/cm2). Then, the role of hepatomimetic shear stress exposed to HepG2 and drug solubility were compared. The highly soluble doxorubicin (DOX) and poorly soluble paclitaxel (PTX) were chosen. Fattigated NPs (AONs) were formed via self-assembly of amphiphilic albumin (HSA)-oleic acid conjugate (AOC). Then, drug-loaded AONs (DOX-AON or PTX-AON) were exposed to a serum-free HepG2 medium at 37 °C and 5% carbon dioxide for 24 h using a real-time ROS sensor chip-based microfluidic system. The cellular efficacy and simultaneous ROS occurrence of free drugs and drug-loaded AONs were compared. The cellular efficacy of drug-loaded AONs varied in a dose-dependent manner and were consistently correlated with real-time of ROS occurrence. Drug-loaded AONs increased the intracellular fluorescence intensity and decreased the cellular efficacy compared to free drugs under dynamic conditions. The half-maximal inhibitory concentration (IC50) values of free DOX (13.4 μg/mL) and PTX (54.44 μg/mL) under static conditions decreased to 11.79 and 38.43 μg/mL, respectively, under dynamic conditions. Furthermore, DOX- and PTX-AONs showed highly decreased IC50 values of 5.613 and 21.86 μg/mL, respectively, as compared to free drugs under dynamic conditions. It was evident that cellular efficacy and real-time ROS occurrence were well-correlated and highly dependent on the drug-loaded nanostructure, drug solubility and physiological shear stress.

Mucoadhesive buccal tablet of leuprolide and its fatty acid conjugate: Design, in vitro evaluation and formulation strategies

This study aimed to design mucoadhesive buccal tablets of leuprolide (LEU) and to manufacture and evaluate the properties of buccal tablets containing LEU-oleic acid conjugate (LOC) and self-assembled LEU-oleic acid nanoparticles (LON), which were developed in a previous study. Hydroxypropyl methylcellulose (HPMC 4000) was used as the mucoadhesive polymer, and tablets were prepared by direct compression. The formulations were characterized by weight, content uniformity, thickness, hardness, swelling index, disintegration time, mucoadhesion time, and drug release. The chosen formulation maintained an adhesion time of up to 6.43 h and a disintegration time of 4.10 h. Drug stability in the mucoadhesive tablets was confirmed after 2 h of storage in human mimic saliva (Phosphate buffer solution pH 6.8). Furthermore, the designed LEU formulation and the LOC and LON developed in a previous study were prepared as buccal tablets and compared. In the dissolution and permeation studies, LON-loaded buccal tablets showed the highest permeation rate. This study suggests that buccal tablets containing self-assembled LON can effectively increase the medication compliance of vulnerable patients (children and the elderly) by improving the bioavailability and permeation rate of LEU.

Physicochemical and Biopharmaceutical Controllability of New Self-Assembled Fatty Acid Conjugated Leuprolide for the Enhanced Anticancer Activity

Background

Leuprolide (LEU), a synthetic nonapeptide analog of naturally occurring gonadotropin-releasing hormone (GnRH), could exert a direct inhibitory activity on the proliferation of prostate cancer cells. However, the short half-life in blood and the biopharmaceutical problem of LEU limit this anticancer activity.

Purpose

To improve its druggability for improving anticancer activity, the amine-group targeted LEU was conjugated with different chain lengths of saturated fatty acids (FAs).

Methods

LEU-fatty acid conjugates (LFCs) were synthesized by exploiting N-hydroxysuccinimidyl (NHS) conjugation chemistry. The physicochemical properties and the self-assembled behaviors of the conjugates were extensively investigated. The in vitro anticancer activity of three LFCs was extensively studied in both 2D monolayer and 3D spheroid culture models of a prostate cancer cell line, PC3.

Results

Three LFCs could be readily self-assembled into nanoparticles (LFNs) with a small size of around 100 nm, positive charges, and exhibited greater permeability rates compared to the same concentration of LEU, excluding LSN. The chain length of FA in conjugate was positively related to the selectivity index between cancer cells and non-cancerous cell lines. All LFCs showed a superior direct antiproliferative effect on cancer cells in the following order: LSC (98.9%) > LPC (86.7%) > LLC (75.0%) > LEU (8.9%) after repeat daily of the same dose strength of LEU for 4 days. In addition, the 3D spheroid model study indicates that all LFCs with a one-time treatment performed a long-acting inhibitory effect on tumor growth as compared to LEU after 7 days.

Conclusion

The conjugation of LEU with different chain lengths of FAs could provide a novel strategy to improve peptide stability and exert an additional superior direct inhibitory effect for the treatment of several hormone-responsive tumor systems using therapeutic peptides.

Hydroxyl Group-Targeted Conjugate and Its Self-Assembled Nanoparticle of Peptide Drug: Effect of Degree of Saturation of Fatty Acids and Modification of Physicochemical Properties

Purpose

To conjugate different degree of saturation of C18 fatty acids (stearic acid, oleic acid, and linoleic acid) with the hydroxyl groups of leuprolide acetate (LEU acetate) and to investigate the controlled release and enhanced permeability through self-assembled nanoparticles (L18FNs).

Methods

Yamaguchi esterification with benzoyl chloride and DMAP (4-Dimethylaminopyridine) allowed the conjugation of the fatty acid to the hydroxyl group of LEU. The three conjugates were then designated as stearic acid-conjugated LEU, LSC, oleic acid-conjugated LEU, LOC, and linoleic acid-conjugated LEU, LLC, respectively. The conjugates (L18FCs) were purified using preparative HPLC (Prep-HPLC) and identified through various instrumental analyses.

Results

The zeta potential, particle size, and morphology of each L18FNs were evaluated. In the case of LSNs, the zeta potential value was relatively low and the particle size was larger than LONs and LLNs owing to the higher hydrophobicity of saturated fatty chain, while the LLNs showed a higher zeta potential and smaller particle size. In human plasma, LLC showed the fastest degradation rate with the highest accumulative drug release. The permeability of L18FNs was analyzed through the Franz diffusion cell experiment, confirming that the degree of saturation of fatty acids affects the permeability of LFNs. While the permeability of LSNs was not significantly enhanced due to higher particle size after nanonization, LONs and LLNs increased 1.56 and 1.85 times in permeation, respectively, compared to LEU.

Conclusion

Utilization of different degree of saturation of fatty acids to conjugate a peptide drug could provide pharmaceutical versatility via self-assembly and modification of physicochemical properties.

Design and evaluation of in vivo bioavailability in beagle dogs of bilayer tablet consisting of immediate release nanosuspension and sustained release layers of rebamipide

The purpose of this study was to develop a once-daily, bilayer matrix tablet with immediate (IR) and sustained release (SR) layers of poorly water-soluble and absorption site dependent rebamipide (RBM) to substitute three times a day IR tablet. Owing to the pH-dependent poor water solubility of RBM in low pH condition, salt-caged nanosuspensions (NSPs) consisting of RBM and poloxamer 407 (POX 407) or poloxamer 188 (POX 188) were prepared using an acid-base neutralization method to increase the dissolution rate, which was subsequently applied to the immediate-release (IR) layer. Polyethylene oxide (PEO) with different molecular weights (PEO 100,000 and PEO 5,000,000) and hydroxypropyl methylcellulose 4000 (HPMC 4000) were then investigated as SR agents to incorporate into the SR layer with pure RBM via wet granulation method. The dissolution profile of the optimized bilayer tablet having 50% IR and 50% SR layer of 300 mg RBM showed that the IR layer could rapidly disintegrate in pH 1.2 buffer solution within 2 h, reaching 50% of drug release from the tablet, followed by an extended drug release from the SR layer in pH 6.8 buffer over 24 h. An in vivo pharmacokinetic study was carried out in beagle dogs to compare the optimal formulation (300 mg RBM bilayer tablet) and the commercial tablet (Mucosta® 100 mg) as a reference. Unexpectedly, despite enhanced dissolution rate in a controlled manner, a designed bilayer tablet had no dose- and dosage form dependent in vivo bioavailability in beagle dogs as compared with IR 100 mg RBM reference tablet. It was evident that solubility in low pH condition, gastric residence time and absorption site of RBM should be carefully considered for designing specific SR or gastroretentive dosage form to improve therapeutic outcomes.

Electrostatic molecular effect of differently charged surfactants on the solubilization capacity and physicochemical properties of salt-caged nanosuspensions containing pH-dependent and poorly water-soluble rebamipide

In this study, the electrostatic molecular effect of differently charged surfactants on the solubilization capacity and physicochemical properties of salt-caged nanosuspensions (NSPs) containing poorly water-soluble drug was investigated. Anionic rebamipide (RBM) was chosen as a model drug because of its poor water solubility in low pH condition and ionizable acidic forms. Negatively charged sodium lauryl sulfate (SLS) and positively charged cetyltrimethylammonium bromide (CTAB) were selected as surfactants for the preparation of NSPs or in the dissolution medium. Salt-caged NSPs surrounded by NaCl were prepared by the HCl-NaOH neutralization method in the presence of poloxamer 407. Interestingly, the addition of positively charged CTAB in the preparation process or the dissolution media could interfere with the solubilization capacity of salt-caged NSPs containing a negatively charged drug via intermolecular electrostatic attraction. In the presence of positively charged CTAB, the salt-caged NSP was disordered in structure via electrostatic attractive interaction with partially ionizable anionic RBM resulting in changes in the physicochemical properties of the salt-caged NSP such as low drug content, increased particle size, decreased dissolution rate, and the formation of water-insoluble precipitates with rough and irregular crystals. This inhibitory effect of CTAB on the dissolution rate of pure RBM and the salt-caged NSP in pH 6.8 intestinal fluid was pronounced in a concentration-dependent manner mainly owing to the formation of precipitates, so-called poorly soluble complexes. When the salt-caged NSP (F1) was dissolved in DW containing CTAB, the dissolution rate decreased more significantly, dissolving less than 20% within 2 h. Depending on the surfactant charges, the charge density and the initial potential were varied during the dissolution of NSPs in deionized water (DW). In contrast, the negatively charged SLS did not significantly change the physicochemical properties of the salt-caged NSP. For example, the dissolution rate of the salt-caged NSP containing SLS in DW or pH 1.2 gastric fluid remained over 90% for 2 h. Surfactants for the formulation or dissolution media should be chosen carefully because of their effect on the physicochemical properties and solubilization capacity of salt-caged NSPs containing poorly water-soluble and ionizable drugs via electrostatic molecular interactions.

Modulation of the clinically accessible gelation time using glucono-d-lactone and pyridoxal 5'-phosphate for long-acting alginate in situ forming gel injectable

The purpose of this study was to design alginate in situ forming gel (ISFG) injectable with clinically acceptable gelation time and controlled release of hydrophobic drug. Milled or unmilled paliperidone palmitate (PPP) was used. The gelation time was controlled by varying the ratios of glucono-d-lactone (GDL) and pyridoxal 5'-phosphate (PLP) in prefilled alginate solution mixtures (ASMs) containing PPP, CaCO₃, GDL and PLP for clinically acceptable injectability. However, the gelation time was varied by the alginate type (M/G ratio), storage condition, and drug solubilizers. This ISFG exhibited 32.15 kPa of the maximal compressive stress without causing pain and stiffness. The ISFG containing conically milled PPP released PPP in a controlled manner without exhibiting any initial burst release for 4 weeks. The current alginate ISFG injectable using new combination of PLP and GDL could be used to deliver long-acting injectable drugs.

Evaluation of the impact of abuse deterring agents on the physicochemical factors of tramadol-loaded tablet and the definition of new abuse deterrent index

In the design of abuse-deterrent formulations (ADFs), pharmaceutical strategies that do not modify the physical and chemical properties of opioid dosage forms should be investigated. Among these, four major drug abusing factors, including particle size by physical modification, swellability, dissolution rate, and solvent extraction, were mainly characterized for evaluating abuse deterrence of narcotics. Tramadol hydrochloride (TMD) was chosen as a model drug. In this study, the frequently used eight generally recognized as safe (GRAS)-listed pharmaceutical excipients, including polyvinyl alcohol (PVA), hydroxypropyl methylcellulose (HPMC 4,000, HPMC 100,000), xanthan gum (XG), cellulose acetate (CA), polyethylene oxide (PEO), carbomer 940 NF, and Compritol® 888 ATO, were selected as abuse deterring agents and used to prepare TMD-loaded tablet. A new abuse-deterrent index (ADI) for compressed TMD-loaded tablets was originally defined and considered as an index of drug abuse deterrence, based on the assumption that it was proportional to particle size and swellability but inversely proportional to dissolution and solvent extraction rates after assigning the categorized five scale scores (one to five) to the four experimental data. The resulting ADI of the selected eight abuse deterring agents in deionized water was given in decreasing order: HPMC 4000 > carbomer 940 > Compritol® 888 ATO > XG > PVA > HPMC 100,000 > PEO, and CA while in 40% hydro-alcoholic solution in the decreasing order: carbomer 940 > HPMC 4,000 ≒ XG > PVA > HPMC 100,000 > PEO > Compritol® 888 ATO > CA. Interestingly, the HPMC 4,000 and carbomer 940 showed the highest ADI and gave drug abuse deterrent potential. This study could provide a pharmaceutical strategy that utilizes a variety of abuse-deterring agents and resist to extraction solvents in designing drug abuse-deterrent formulations and establishing their standard guidelines for regulatory authorities.

Effect of pH adjustment and ratio of oppositely charged polymers on the mechanistic performance and sustained release of volatile perfume in interpolyelectrolyte complex microcapsules

In this study, volatile perfume was encapsulated in microcapsules (MCs) via interpolyelectrolyte complexes (IPECs) of oppositely charged polymers, with high encapsulation efficiency, to be delivered in a sustained manner. Positively charged chitosan (CTS) and negatively charged Eudragit® S100 (ES100) were used as eco-friendly biopolymers. Limonene (LMN) was selected as the model perfume. First, the solution of LMN in ethyl acetate and poloxamer 407 (POX407) in acidic solution was emulsified using ultrasonication. CTS and ES100 were added in that particular order to form o/w emulsion. LMN-loaded microcapsules (LMN-MCs) were prepared by adjusting the pH and freeze-drying for solidification. The electrostatic interactions of CTS and ES100 to form IPECs were highly dependent on pH, changing in the microscopic images of emulsion droplets and zeta potential. The NH₃⁺ group of CTS and the COO^- group of ES100 caused the electrostatic interactions at a specific pH. The formation mechanism of LMN-MCs was successfully validated using instrumental analysis, charge density, and energy dispersive X-ray spectrometer (EDS) mapping. Encapsulation efficiency, loading content, and release rates of LMN-MCs varied according to the ratios of CTS and ES100, demonstrating optimal performance at a 1:1 ratio. The current LMN-MCs could provide a simple manufacturing process with high performance in terms of encapsulation efficiency (>94%), drug loading, yield and sustained release of volatile perfume for 120 h.

Role of Surfactant Micellization for Enhanced Dissolution of Poorly Water-Soluble Cilostazol Using Poloxamer 407-Based Solid Dispersion via the Anti-Solvent Method

This study aimed to investigate the role of micellization of sodium lauryl sulfate (SLS) in poloxamer 407 (POX)-based solid dispersions (POX-based SDs) using the anti-solvent method in enhancing the dissolution rate of practically water-insoluble cilostazol (CLT). Herein, SLS was incorporated into CLT-loaded SDs, at a weight ratio of 50:50:10 of CLT, POX, and SLS by three different methods: anti-solvent, fusion (60 °C), and solvent (ethanol) evaporation. The SDs containing micellar SLS in the anti-solvent method were superior in the transformation of the crystalline form of the drug into a partial amorphous state. It was notable that there was an existence of a hydrophobic interaction between the surfactant and the hydrophobic regions of polymer chain via non-covalent bonding and the adsorption of micellar SLS to the POX-based SDs matrix. Moreover, SLS micellization via the anti-solvent method was effectively interleaved in SDs and adhered by the dissolved CLT, which precluded drug particles from aggregation and recrystallization, resulting in improved SD wettability (lower contact angle) and reduced particle size and dissolution rate. In contrast, SDs without micellar SLS prepared by the solvent method exerted drug recrystallization and an increase of particle size, resulting in decreased dissolution. Incorporation of surfactant below or above critical micellar concentration (CMC) in SDs using the anti-solvent method should be considered in advance. Dissolution results showed that the pre-added incorporation of micellar SLS into POX-based SDs using the anti-solvent method could provide a way of a solubilization mechanism to enhance the dissolution rate of poorly water-soluble drugs.

Double-Controlled Release of Poorly Water-Soluble Paliperidone Palmitate from Self-Assembled Albumin-Oleic Acid Nanoparticles in PLGA in situ Forming Implant

Purpose

To investigate the effects of solvents on the formation of self-assembled nanonization of albumin-oleic acid conjugates (AOCs) using a solvent exchange mechanism for the construction of in situ forming implants (ISFI).

Methods

A poorly water-soluble drug, paliperidone palmitate (PPP), was chosen as the model drug. AOC was synthesized with the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) reaction. Dichloromethane, tetrahydrofuran, ethanol, N-methyl-2-pyrrolidone, dimethyl sulfoxide, and deionized water were selected to investigate the formation of self-assembled AOC nanoparticles (AONs). The volume ratios of organic solvents against water could determine the miscibility, injectability, and in situ nanonizing capability without aggregation.

Results

As the polarity of the organic solvents increased, the AONs exhibited a spherical shape, and the larger the volume of the solvent, the smaller the size of the AONs. To use AOC in ISFI for controlled release of PPP, poly(d,l-lactide-co-glycolide) (PLGA) was combined with the AOC in 2 mL of N-methyl-2-pyrrolidone and water solution (1.8/0.2 ratio). The release rates of all formulations exhibited similar curve patterns overall but were more controlled in decreasing order as follows: AOC, PLGA, and AOC/PLGA for 14 days.

Conclusion

A combined formulation of AOC and PLGA was found to effectively control the initial burst release of the drug.

Film-Forming Nanogels: Effects of Nanocarriers and Film-Forming Gel on the Sustained Release of Curcumin

BACKGROUND

Although film-forming hydrogels possess the advantages of both film and hydrogel dosage forms, certain limitations still remain.

OBJECTIVE

This study aims to investigate the use of film-forming hydrogels and the effects of nanocarriers on the sustained release of a poorly water-soluble drug, curcumin.

METHODS

The film-forming hydrogels contained either zein or polyvinylpyrrolidone as a film former, in addition to hydroxypropyl methylcellulose, oleic acid, ethanol and water. Curcumin was encapsulated in poly(lacticco- glycolic acid) and gelatine nanoparticles using a sonoprecipitation method. Free drug and drug-loaded nanoparticles were later dispersed into blank hydrogels to produce the film-forming nanogels.

RESULTS

The results suggested that the encapsulation of curcumin in nanoparticles could reduce the drug particle size to less than 200nm for easier diffusion and could shield curcumin from chemical interactions that limit its topical permeability. Curcumin was more compatible with gelatine nanoparticles than with poly(lactic-coglycolic acid) nanoparticles, and gelatine nanoparticles, in turn, were more compatible with zein than with polyvinylpyrrolidone film-forming nanogels. Therefore, gelatine nanoparticles in zein film-forming nanogels greatly elevated the permeability of curcumin by over five times that afforded by gelatine nanoparticles in polyvinylpyrrolidone film-forming nanogels.

CONCLUSION

This research suggested that film-forming nanogel is a promising drug delivery system for both improved permeability and sustained topical diffusion of the extremely hydrophobic drug curcumin depending on the compatibility between the nanocarrier and the film-forming hydrogel.

Hydrophobic and Hydrophilic Film-Forming Gels for the Controlled Delivery of Drugs with Different Levels of Hydrophobicity

BACKGROUND

This study aimed to evaluate the effects of hydrophobic and hydrophilic Film-Forming Gels (FFGs) on the controlled delivery of drugs with different levels of hydrophobicity.

METHODS

This evaluation was carried out by employing zein and polyvinylpyrrolidone as hydrophobic and hydrophilic film-forming agents, respectively, in combination with hydroxypropyl methylcellulose functionalized as a hydrogel basement at a ratio that had been optimized to achieve the fastest drying time. Free curcumin or terbinafine hydrochloride was subsequently dispersed into blank FFGs to produce the final FFG formulations.

RESULTS

Although the extreme hydrophobicity of curcumin strongly limited its topical permeability compared to that of terbinafine hydrochloride, zein FFGs clearly resulted in a favourable sustained release system for highly hydrophobic drugs, such as curcumin. Moreover, polyvinylpyrrolidone would be highly effective for the sustained release of a less hydrophobic drug, such as terbinafine hydrochloride. Analyses of the wettability, surface morphology, chemical interactions and crystallinity of FFGs also helped to elucidate the mechanisms of their drug release profiles.

CONCLUSION

This fundamental finding is beneficial for further design studies on FFGs as sustained drug delivery systems for topical drugs with a wide range of hydrophobicities.

Development of film-forming gel containing nanoparticles for transdermal drug delivery

Despite several studies on film-forming systems with the advantages of both the film and the hydrogel, there are still no effective systems for fast film formation with a high level of control over permeability. In this study, a film-forming system for the delivery of nanomedicine, termed a film-forming nanogel (FFN), was produced and investigated for the first time to meet this need. The objective of this research was to study a new generation of film-forming hydrogels (FFHs) loaded with curcumin nanoparticles (CUR-GNPs) for transdermal applications. FFHs were prepared by employing zein and HPMC 4000 as film-forming polymers. Meanwhile, CUR-GNPs were obtained by sonoprecipitation. The film-forming time, particle characteristics and FFN drug release profile were assessed. The optimized FFH had a smooth surface and a fast drying time of 6 min and 4.5 min in vitro and ex vivo, respectively. Additionally, high, sustained drug permeation from the FFN was observed after 24 h. The FFH containing CUR-GNPs showed potential for application in transdermal drug delivery with a fast film-forming time, uniform particle dispersion and high, sustained drug permeation.