Jiraphong Suksiriworapong

Physicochemical properties and skin permeation of Span 60/Tween 60 niosomes of ellagic acid.

Ellagic acid (EA) is a potent antioxidant phytochemical substance which has limitation to use due to its poor biopharmaceutical properties, low solubility and low permeability. The aim of the present study was to develop niosomal formulations obtained from the mixture of Span 60 and Tween 60 that could encapsulate EA for dermal delivery. The EA-loaded niosomes were prepared with 1:0, 2:1, 1:1, 0:1 Span 60 and Tween 60, using polyethylene glycol 400 (PEG 400), propylene glycol (PG) or methanol (MeOH) as a solubilizer. The influence of formulations on vesicle size, entrapment efficiency and stability of EA-loaded niosomes was investigated. It was found that all ratios of surfactants could produce EA-loaded niosomes when using 15% (v/v) PG, 15% (v/v) PEG 400 or 20% (v/v) MeOH. The niosomes were spherical multilamellar vesicles showing the localization of EA in the vesicles. The vesicle sizes of the niosomes after extrusion were 124-752 nm with PI less than 0.4. The percentages of entrapment efficiency (% E.E.) of all EA-loaded niosomes varied between 1.35% and 26.75% while PEG 400 niosomes gave the highest % E.E. The most stable and highest entrapped formulation was 2:1 Span 60 and Tween 60 niosomes. Additionally, the in vitro skin permeation revealed that penetration of EA from the niosomes depended on vesicle size, the amount of EA entrapped and the added solubilizers which could act as a permeation enhancer. From skin distribution study, the EA-loaded niosomes showed more efficiency in the delivery of EA through human epidermis and dermis than EA solution. The results indicated that the Span 60 and Tween 60 niosomes may be a potential carrier for dermal delivery of EA.

Investigation of polymer and nanoparticle properties with nicotinic acid and p-aminobenzoic acid grafted on poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) via click chemistry.

In this study, the grafting of nicotinic acid and p-aminobenzoic acid (PABA) onto poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) was performed by Huisgens 1,3-dipolar cycloaddition, also known as click chemistry. Concentrations used for grafting were 0.10, 0.20, and 0.30 molar ratios with respect to caproyl units. The grafted copolymers were successfully obtained at all ratios as confirmed by NMR, GPC, and FT-IR. According to the DSC results, the polymorphisms of these grafted copolymers were mostly changed from semicrystalline to amorphous depending on the type and the amount of grafting compounds. TGA thermograms showed different thermal stabilities of the grafted copolymers compared to the original copolymers. Cytotoxicity results from HUVEC models suggested that the toxicity of grafted nanoparticles increased with the molar ratios of grafting units. Due to differences in molecular structure between nicotinic acid and PABA, physicochemical properties (particle size and surface charge) of grafted copolymer nanoparticles were substantially different. With increasing molar ratio of the grafting units, the particle size of blank nanoparticles tended to increase, resulting from an increase in the hydrophobic fragments of the grafted copolymer. Ibuprofen was chosen as a model drug to evaluate the interaction between grafted copolymers and loaded drug. After ibuprofen loading, the particle size of the loaded nanoparticles of both grafted copolymers increased compared to that of the blank nanoparticles. Significant differences in loading capacity between nicotinic acid and PABA grafted copolymer nanoparticles were clearly shown. This is most likely a result of different compatibility between each grafting compound and ibuprofen, including hydrogen bond interaction, π-π stacking interaction, and steric hindrance.

Precipitation-lyophilization-homogenization (PLH) for preparation of clarithromycin nanocrystals: Influencing factors on physicochemical properties and stability

Nanocrystals is one of effective technologies used to improve solubility and dissolution behavior of poorly soluble drugs. Clarithromycin is classified in BCS class II having low bioavailability due to very low dissolution behavior. The main purpose of this study was to investigate an efficiency of clarithromycin nanocrystals preparation by precipitation-lyophilization-homogenization (PLH) combination method in comparison with high pressure homogenization (HPH) method. The factors influencing particle size reduction and physical stability were assessed. The results showed that the PLH technique provided an effective and rapid reduction of particle size of nanocrystals to 460 ± 10 nm with homogeneity size distribution after only the fifth cycle of homogenization, whereas the same size was attained after 30 cycles by the HPH method. The smallest nanocrystals were achieved by using the combination of poloxamer 407 (2%, w/v) and SLS (0.1%, w/v) as stabilizers. This combination could prevent the particle aggregation over 3-month storage at 4 °C. The results from SEM showed that the clarithromycin nanocrystals were in cubic-shaped similar to its initial particle morphology. The DSC thermogram and X-ray diffraction pattern of nanocrystals were not different from the original drug except for intensity of peaks which indicated the presenting of nanocrystals in the crystalline state and/or partial amorphous form. In addition, the dissolution of the clarithromycin nanocrystals was dramatically increased as compared to the coarse clarithromycin.

Functionalized (poly(ɛ-caprolactone))2-poly(ethylene glycol) nanoparticles with grafting nicotinic acid as drug carriers

Nicotinic acid was grafted on (poly(ɛ-caprolactone))(2)-poly(ethylene glycol) copolymers that were used for the preparation of nanoparticles with the objectives to monitor particle size and to optimize the drug loading capacity as well as the release profile of the particles. Increasing amounts of grafting nicotinic acid increased the particle size as a result of an enhanced hydrophobicity of the copolymer. Ibuprofen and indomethacin with two different molecular characteristics were selected as model drugs to be bound to the nanoparticles. The presence of grafting nicotinic acid enhanced the loading capacity for both drugs compared to the nanoparticles without nicotinic acid. However, no correlation between amount of grafting nicotinic acid and loading capacity was observed. The release characteristic of both drugs was fitted to the Higuchi model indicating Fickian diffusion. The release characteristic of indomethacin mainly depended on the crystalline property of the copolymer whereas that of ibuprofen was additionally influenced by the hydrogen bonding between drug and grafted copolymer.

Dissolution enhancement and in vitro performance of clarithromycin nanocrystals produced by precipitation–lyophilization–homogenization method

The gastroduodenal diseases caused by Helicobacter pylori were commonly treated with antibiotic clarithromycin as a standard regimen. According to the poorly water-soluble of clarithromycin, the nanocrystal formulation was prepared. The aim of this study was to investigate an enhancement effect of clarithromycin nanocrystals produced by precipitation-lyophilization-homogenization (PLH) method on the saturation solubility, dissolution velocity, antibiotic activity, permeability through the gastric mucus and cellular permeability. Poloxamer 407 and sodium lauryl sulfate (SLS) were chosen as combined stabilizers in the nanocrystal system. The obtained clarithromycin nanocrystals were identified as cubic particles by SEM with a bulk population of approximately 400nm existed in crystalline and/or partial amorphous form as investigated by DSC and XRPD. The saturation solubility of the clarithromycin nanocrystals was increased by 1.5- and 6-folds higher than clarithromycin powder in buffer pH 5.0 and 6.8, respectively. The dissolution profiles of clarithromycin nanocrystals at pH 5.0 and 6.8 were significantly different from clarithromycin powder and the marketed product (f1 value >15 and f2 value <50). All dissolution parameters (relative dissolution rate, percent dissolution efficiency and mean dissolution time) showed that clarithromycin nanocrystals had higher dissolution rate when compared with the clarithromycin powder, the lyophilized coarse suspension and the marketed product. The bioassay study by diffusion agar method showed a maintained antibiotic activity of clarithromycin nanocrystals solubilized in buffer solution which was greater potency than the lyophilized coarse suspension and the clarithromycin powder. Additionally, the nanocrystals possessed higher permeability through gastric mucus and cellular monolayer of Caco-2 and NCI-N87 cells as compared to the lyophilized coarse suspension and the clarithromycin powder. The results indicated that, the developed clarithromycin nanocrystals were a potential delivery system that exerts more effectiveness in H. pylori eradication.

Comparison of poly(ε-caprolactone) chain lengths of poly(ε-caprolactone)-co-d-α-tocopheryl-poly(ethylene glycol) 1000 succinate nanoparticles for enhancement of quercetin delivery to SKBR3 breast cancer cells

This study aimed to investigate the effect of the different hydrophobic chain lengths of poly(ε-caprolactone)-co-d-α-tocopheryl polyethylene glycol 1000 succinate (P(CL)-TPGS) copolymers on the nanoparticle properties and delivery efficiency of quercetin to SKBR3 breast cancer cells. The 5:1, 10:1 and 20:1 P(CL)-TPGS copolymers were fabricated and found to be composed of 25.0%, 45.2% and 66.8% of hydrophobic P(CL) chains with respect to the polymer chain, respectively. The DSC measurement indicated the microphase separation of P(CL) and TPGS segments. The crystallization of P(CL) segment occurred when the P(CL) chain was higher than 25% due to the restricted mobility of P(CL) by TPGS. The longer P(CL) chain had the higher crystallinity while decreasing the crystallinity of TPGS segment. The increasing P(CL) chain length increased the particle size of P(CL)-TPGS nanoparticles from 20 to 205 nm and enhanced the loading capacity of quercetin due to the more hydrophobicity of the nanoparticle core. The release of quercetin was retarded by an increase in P(CL) chain length associated with the increasing hydrophobicity and crystallinity of P(CL)-TPGS copolymers. The P(CL)-TPGS nanoparticles potentiated the toxicity of quercetin to SKBR3 cells by at least 2.9 times compared to the quercetin solution. The cellular uptake of P(CL)-TPGS nanoparticles by SKBR3 cells occurred through cholesterol-dependent endocytosis. The 10:1 P(CL)-TPGS nanoparticles showed the highest toxicity and uptake efficiency and could be potentially used for the delivery of quercetin to breast cancer cells.

Self-aggregation of cationically modified poly( ε -caprolactone) 2 - co -poly(ethylene glycol) copolymers: Effect of cationic grafting ligand and poly( ε -caprolactone) chain length

Cationic copolymers have been attractive to investigate due to their potential to complexation with anionic drugs and expected to use in the pharmaceutical application. In this study, the modified poly(ε-caprolactone)2-co-poly(ethylene glycol) copolymers (P(CL)2-PEG) were successfully synthesized by click reaction. The amount of small molecular cationic ligand, propargyltrimethyl ammonium iodide, was varied and grafted onto various mole ratios of P(CL) to PEG. The effects of P(CL) chain length and amount of the grafting cationic ligand on physicochemical properties of polymers and particles were studied. The number-average molecular weights of the copolymers grafted with cationic ligand were found ranging between 10,000 and 23,000g/mol as investigated by NMR. From DSC study, the results showed that the grafting ligand affected thermal behaviors of the copolymers by increasing the glass transition temperature and decreasing the melting temperature of the copolymers. Furthermore, these cationic copolymers could self-aggregate with their critical aggregation concentration depending on mole ratios of hydrophilic to hydrophobic portions. The particles containing higher amounts of the cationic ligand tended to aggregate in both acidic and basic pH environment and at high salt concentration. Additionally, particle size, size distribution (PdI), and morphology of self-assembling particles varied depending on P(CL) chain length and the amount of the grafting cationic ligand. The synthesized cationic copolymer showed a capability to encapsulate a high negatively charged drug, enoxaparin, with an encapsulation efficiency of 87%. After drug incorporation, the particles substantially changed in size, shape, PdI, and zeta potential to become more suitable for drug delivery. These cationic copolymers with flexible properties will be the candidate for further development as carriers for the delivery of negatively charged drugs.

Enhanced toxicity and cellular uptake of methotrexate-conjugated nanoparticles in folate receptor-positive cancer cells by decorating with folic acid-conjugated d-α-tocopheryl polyethylene glycol 1000 succinate.

Folic acid-conjugated d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS-FOL) decorated methotrexate (MTX)-conjugated nanoparticles were developed for targeted delivery of MTX to folate receptor-expressed tumor cells. The synthesis of TPGS-FOL followed 3-step process. Firstly, the terminal hydroxyl group of TPGS was converted to sulfonyl chloride using mesyl chloride in comparison with nosyl and tosyl chlorides. The highest conversion efficiency and yield were obtained by mesyl chloride due to the formation of higher reactive intermediate in a presence of triethylamine. Secondly, the substitution of sulfonyl group by sodium azide produced considerably high yield with conversion efficiency of over 90%. Lastly, the coupling reaction of azido-substituted TPGS and propargyl folamide by click reaction resulted in 96% conjugation efficiency without polymer degradation. To fabricate the folate receptor-targeted nanoparticles, 10 and 20%mol MTX-conjugated PEGylated poly(ϵ-caprolactone) nanoparticles were decorated with TPGS-FOL. The size and size distribution of MTX-conjugated nanoparticles relatively increased with %MTX. The MTX release from the nanoparticles was accelerated in acidic medium with an increase of %MTX but retarded in physiological pH medium. The decoration of TPGS-FOL onto the nanoparticles slightly enlarged the size and size distribution of the nanoparticles; however, it did not affect the surface charge. The cytotoxicity and cellular uptake of MCF-7 cells demonstrated that 10% MTX-conjugated nanoparticles and FOL-decorated nanoparticles possessed higher toxicity and uptake efficiency than 20% MTX-conjugated nanoparticles and undecorated nanoparticles, respectively. The results indicated that FOL-10% MTX-conjugated nanoparticles exhibited potential targeted delivery of MTX to folate receptor-expressed cancer cells.

Properties of acyl modified poly(glycerol-adipate) comb-like polymers and their self-assembly into nanoparticles

ABSTRACT There is an increasing need to develop bio‐compatible polymers with an increased range of different physicochemical properties. Poly(glycerol‐adipate) (PGA) is a biocompatible, biodegradable amphiphilic polyester routinely produced from divinyl adipate and unprotected glycerol by an enzymatic route, bearing a hydroxyl group that can be further functionalized. Polymers with an average Mn of ∼13 kDa can be synthesized without any post‐polymerization deprotection reactions. Acylated polymers with fatty acid chain length of C4, C8, and C18 (PGAB, PGAO, and PGAS, respectively) at different degrees of substitution were prepared. These modifications yield comb‐like polymers that modulate the amphiphilic characteristics of PGA. This novel class of biocompatible polymers has been characterized through various techniques such as FT‐IR, 1H NMR, surface, thermal analysis, and their ability to self‐assemble into colloidal structures was evaluated by using DLS. The highly tunable properties of PGA reported herein demonstrate a biodegradable polymer platform, ideal for engineering solid dispersions, nanoemulsions, or nanoparticles for healthcare applications.

Investigation of pH Influence on Skin Permeation Behavior of Weak Acids Using Nonsteroidal Anti-Inflammatory Drugs

As a continuing effort to understand the skin permeation behavior of weak acids and bases, the objectives of the present study were to evaluate skin permeation of nonsteroidal anti-inflammatory drugs (NSAIDs) under the influence of pH, investigate the mechanism of pH effect, and examine a previous hypothesis that the effective skin pH for drug permeation is different from donor solution pH. In vitro permeability experiments were performed in side-by-side diffusion cells with diclofenac, ibuprofen, flurbiprofen, ketoprofen, and naproxen and human skin. The donor solution pH significantly affected skin permeation of NSAIDs, whereas no effect of the receiver pH was observed. Similar to previous observations, the apparent permeability coefficient versus donor solution pH relationships deviated from the predictions (fractions of unionized NSAIDs) according to the acid/base theory. The influences of the viable epidermis barrier, polar pathway transport, ion permeation across skin, and effective skin pH were investigated. The effective pH values for skin permeation determined using the NSAIDs (weak acids) in this study were different from those obtained previously with a weak base at the same donor solution pH conditions, suggesting that the observed permeability-pH relationships could not be explained solely by possible pH differences between skin and donor solution.As a continuing effort to understand the skin permeation behavior of weak acids and bases, the objectives of the present study were to evaluate skin permeation of nonsteroidal anti-inflammatory drugs (NSAIDs) under the influence of pH, investigate the mechanism of pH effect, and examine a previous hypothesis that the effective skin pH for drug permeation is different from donor solution pH. In vitro permeability experiments were performed in side-by-side diffusion cells with diclofenac, ibuprofen, flurbiprofen, ketoprofen, and naproxen and human skin. The donor solution pH significantly affected skin permeation of NSAIDs, whereas no effect of the receiver pH was observed. Similar to previous observations, the apparent permeability coefficient versus donor solution pH relationships deviated from the predictions (fractions of unionized NSAIDs) according to the acid/base theory. The influences of the viable epidermis barrier, polar pathway transport, ion permeation across skin, and effective skin pH were investigated. The effective pH values for skin permeation determined using the NSAIDs (weak acids) in this study were different from those obtained previously with a weak base at the same donor solution pH conditions, suggesting that the observed permeability-pH relationships could not be explained solely by possible pH differences between skin and donor solution.