Elaboration of capsules from Pickering double emulsion polymerization stabilized solely by cellulose nanocrystals.

Pickering double oil-in-water-in-oil emulsions O/W/O were stabilized using solely cellulose nanocrystals (CNCs), which were modified by introducing surface brominated functions. The emulsions were formulated using only bio-friendly components, among which isopropyl myristate as oil phase, hydroxyl oligoethylene glycol methacrylate (OEGMA) as macromonomer, tetraethylene glycol diacrylate (TEGDA) as cross-linker, and CNCs as stabilizing particles. Formulation parameters could be tuned easily to modulate the fraction of inner emulsion droplets within the double emulsion drops or change the monomer(s) composition within the aqueous phase. The latter was further polymerized to synthesize matrix capsules. The obtained objects showed good resistance to the vacuum and were efficiently used as promising encapsulation vessels. Both hydrophobic and hydrophilic model dyes were encapsulated, with an encapsulation efficiency of about 90%.

Isolation of new phytometabolites from Alpinia galanga willd rhizomes.

The current research was aimed to isolate newer phyto-metabolites from rhizomes of Alpinia galanga plant. Study involved preparation of Alpinia galanga rhizome methanolic extract, followed by normal phase column chromatography assisted isolation of new phytometabolites (using different combinations of chloroform and methanol), and characterization (by UV, FTIR, 13C-NMR, 1H-NMR, COSY, DEPT and Mass spectrometry). The isolation and characterization experiment offered two phytometabolites: an ester (Ag-1) and tetrahydronapthalene type lactone (Ag-2). Present study concludes and reports the two phytometabolites, benzyl myristate (Ag-1) and 3-Methyl-6α, 8ß-diol-7-carboxylic acid tetralin-11, 9ß-olide (Ag-2) for the first time in Alpinia galanga rhizome. The study recommends that these phytometabolites Ag-1 and Ag-2 can be utilized as effective analytical biomarkers for identification, purity and quality control of this plant in future.

Effect of Chemical Penetration Enhancer-Adhesive Interaction on Drug Release from Transdermal Patch: Mechanism Study Based on FT-IR Spectroscopy, 13C NMR Spectroscopy, and Molecular Simulation.

Chemical penetration enhancers (CPEs) are commonly added into transdermal patches to impart improved skin permeation of drug. However, significant unexplained variability in drug release kinetics in transdermal patches is possible as a result of the addition of CPEs; investigations into the underlying mechanisms are still limited. In the present study, a diverse set of CPEs was employed to draw broad conclusions. Solubility parameters of CPEs and acrylate pressure-sensitive adhesive were calculated by molecular dynamics simulation and Fedors group contribution method to evaluate drug-adhesive miscibility. CPE-adhesive interaction was characterized by FT-IR study, 13C NMR spectroscopy, and molecular docking simulation. Results showed that release enhancement ratio (ERR) of CPEs for zolmitriptan was rank ordered as isopropyl myristate > azone > Plurol Oleique® CC497 > Span® 80 > N-methylpyrrolidone > Transcutol® P. It was found that solubility parameter difference (Δδ) between CPE and adhesive was negatively related with ERR. It was proved that hydrogen bonding between CPE and adhesive would increase drug release rate, but only if the CPE showed good miscibility with adhesive. CPE like isopropyl myristate, which had good miscibility with adhesive, could decrease drug-adhesive interaction leading to the release of drug from adhesive.

Development of a gel-in-oil emulsion as a transdermal drug delivery system for successful delivery of growth factors.

Growth factors (GFs) are indispensable in regenerative medicine because of their high effectiveness. However, as GFs degenerate easily, the development of a suitable carrier with improved stability for GFs is necessary. In this study, we developed a gel-in-oil (G/O) emulsion technology for the transdermal delivery of growth factors. Nanogel particles prepared with heparin-immobilized gelatin that can bind growth factors were dispersed in isopropyl myristate. The particle size of the G/O emulsion could be controlled by changing the surfactant concentration, volume ratio of the water phase to the oil phase, and gelatin concentration. In vitro skin penetration studies showed better penetration through the stratum corneum of fluorescent proteins containing G/O emulsions than of the aqueous solution of GF. Similarly, an in vivo study showed an angiogenesis-inducing effect after transdermal application of GF-immobilized G/O emulsion. Angiogenesis in mice was confirmed owing to both an increased blood vessel network and higher hemoglobin content in the blood. Therefore, the G/O emulsion could be a promising carrier for GFs with better stability and can effectively deliver GFs at the target site.

Advanced Formulation Design for Topical Creams Assisted with Vibrational Spectroscopic Imaging.

Vibrational spectroscopic imaging has become useful analytical tools for quality control of drug products. In this study, we applied microscopic attenuated total reflection (ATR)-IR and confocal Raman microscopy to elucidate microscopic structure of creams and for the formulation design in the development of semi-solid drug products. The model creams were prepared with prednisolone (PRD) and fluconazole (FLC) as active pharmaceutical ingredients and oily solvents such as mineral oil (MO), isopropyl myristate (IPM), benzyl alcohol (BA) and diethyl sebacate (DES). As a result of microscopic ATR-IR imaging, several domains indicating oily internal phase were observed, which had absorption around 1732 and 1734 cm-1 derived from MO, IPM and DES. In addition, domains of BA around 1009 cm-1 were observed at the complemental or similar position in the formulation with MO or DES, respectively. These results suggested that the creams were oil-in-water type and the distribution of domains would reflect the compatibility of the solvents. The contents of PRD and BA were determined quantitatively in each layer after the intentional separation of the creams and the results agreed well with the imaging analysis. Whereas, confocal Raman imaging allowed to visualize the distribution of the components in depth direction as well as two-dimensional plane. In particular, the Raman imaging would ensure the coexistence of FLC and BA as oily phase in the cream. From these results, the feasibility of spectroscopic imaging techniques was successfully demonstrated for the formulation design of semi-solid dosage forms.

Associating chitosan and microemulsion as a topical vehicle for the administration of herbal medicines.

A viscous solution of low molecular weight chitosan (CH) at 5% w/v (10.2 kDa, 75 % deacetylated, 1451 cP at 25 °C) was associated with a microemulsion (ME) that undergoes a phase transition after water absorption in situ (≈28 % w/w), forming a more viscous liquid crystal, which was potentially evaluated as a topical vehicle. The ME was selected from a phase diagram, selecting a composition based on Tween® 80 (52 %), myristate isopropyl (28 %), and the aqueous phase (water and polyethylene glycol 400, 60:40 w/w) (20 %), which was after replaced by CH and herbal medicines (HM). HM are alternatives to treat candidiasis, and Stryphnodendron adstringens shell extract, characterized by molecular networking, and Melaleuca alternifolia Chell essential oil (46 % of terpinen-4-ol), showed in vitro activity against Candida albicans. Associating CH in ME improved the mechanical properties of the topical formulation, as adhesiveness, which is an advantageous feature for the topical treatment of vulvovaginal candidiasis.

Preparation and Characterization of Microemulsions Based on Antarctic Krill Oil.

Antarctic krill oil is high in nutritional value and has biological functions like anti-inflammation and hypolipidemic effects. But it has and unpleasant smell, and unsaturated fatty acids are prone to oxidative deterioration. Its high viscosity and low solubility in water make it difficult for processing. Microemulsion can be a new promising route for development of krill oil product. We determined a formula of krill oil-in-water microemulsion with krill oil: isopropyl myristate = 1:3 as oil phase, Tween 80:Span 80 = 8:2 as surfactant, ethanol as co-surfactant and the mass ratio of surfactant to co-surfactant of 3:1. After screening the formula, we researched several characteristics of the prepared oil-in-water microemulsion, including electrical conductivity, microstructure by transmission electron microscope and cryogenic transmission electron microscope, droplet size analysis, rheological properties, thermal behavior by differential scanning calorimeter and stability against pH, salinity, and storage time.

Role of sodium l-cysteine alginate conjugate and isopropyl myristate to enhance the permeation enhancing activity of BCS class III drug from TDDS; optimization by central composite design and in vivo pharmacokinetics study.

OBJECTIVE: The objective of the present research was to study the effect and optimization of sodium alginate l-cysteine conjugate and permeation enhancer on permeation of high soluble low permeable ropinirole hydrochloride from the transdermal formulation. METHODS: Sodium alginate l-cysteine conjugate was prepared and characterized and the same was added into a transdermal formulation along with IPM as a permeation enhancer. Twelve primary formulations were prepared by solvent casting method and evaluated. The results were fed into Design Expert® Software to obtain optimized formulation. The optimized formulation was evaluated for physicochemical, ex vivo permeation, stability, skin irritation, and pharmacokinetic studies. RESULTS: The results of the characterization of prepared sodium alginate l-cysteine conjugate confirmed the thiolation process. Stability studies suggested that the drug was compatible with all the excipients. SEM images of the transdermal patch revealed that the amorphous drug was uniformly distributed. From the design space, the optimized formulation from the polymer's ratio (SA: SACC; 4:6) and IPM 9.5%w/w of polymers weight showed target steady state flux 9.004 µg/cm2/h with maximum drug permeation. The increased target flux and maximum drug permeation from an optimized patch suggested that there was an effect of SACC on ropinirole hydrochloride permeation in the presence of IPM as a permeation enhancer. Pharmacokinetic studies in rabbits showed that the optimized patch improved bioavailability as compared to marketed oral tablets. CONCLUSIONS: The study was concluded that there was a positive effect of sodium alginate l-cysteine conjugate and IPM on ropinirole hydrochloride permeation from the transdermal formulation.

Choline and amino acid based biocompatible ionic liquid mediated transdermal delivery of the sparingly soluble drug acyclovir.

Transdermal delivery of drugs is more challenging for drugs that are insoluble or sparingly soluble in water and most organic solvents. To overcome this problem, ionic liquid (IL)-mediated ternary systems have been suggested as potential drug carriers. Here, we report potent ternary (IL-EtOH-IPM) systems consisting of biocompatible ILs, ethanol (EtOH), and isopropyl myristate (IPM) that can dissolve a significant amount of the sparingly soluble drug acyclovir (ACV). The ternary systems were optically transparent and thermodynamically stable with a wide range of IL pertinence. An in vitro drug permeation study showed that the ILs in the ternary systems dramatically enhanced ACV permeation into and across the skin. Fourier Transform Infrared spectroscopy of the stratum corneum (sc) after treatment with ternary systems showed that the skin barrier function was reduced by disturbance of the regularly ordered arrangement of corneocytes and modification of the surface properties of the sc during permeation. Histological analysis, and skin irritation studies using a reconstructed human epidermis model showed the safety profile of the ternary system, and there were no significant changes in the structures of the sc, epidermis, and dermis. Therefore, ternary systems containing biocompatible ILs are promising for transdermal delivery of insoluble or sparingly soluble drugs.

Self-nanoemulsifying drug delivery system to improve transcorneal permeability of voriconazole: in-vivo studies.

OBJECTIVE: This study investigates the effectiveness of self-nanoemulsifying drug delivery system (SNEDDS) in improving voriconazole transcorneal permeability. METHODS: Voriconazole-SNEDDS was prepared with isopropyl myristate, PEG 400, Tween 80® and Span 80® and was subjected for physicochemical characterization after reconstitution with NaCl 0.9% (1/9; v/v). In-vitro antifungal activity was assessed and compared with the marketed formulation. In-vivo studies, namely ocular irritation test via modified Draize test and pharmacokinetic study, were investigated using rabbit as animal model. KEY FINDINGS: Voriconazole-SNEDDS presented a droplet size of 21.353 ± 0.065 nm, a polydispersity index of 0.123 ± 0.003, a pH of 7.205 ± 0.006 and an osmolarity of 342.667 ± 2.517 mOsmol/l after reconstitution with NaCl 0.9%. Voriconazole-SNEDDS minimum inhibitory concentration (MIC90 ) was similar to the one of marketed formulation for Candida species while it was significantly lower (P < 0.001) for Aspergillus fumigatus. Draize test revealed that Voriconazole-SNEDDS was safe for ocular administration. Voriconazole maximum concentration (5.577 ± 0.852 µg/ml) from SNEDDS was higher than marketed formulation (Cmax  = 4.307 ± 0.623 µg/ml), and the Tmax was delayed to 2 h. The area under the concentration-time curve value of Voriconazole-SNEDDS was improved by 2.419-fold. CONCLUSION: Our results suggest that SNEDDS is a promising carrier for voriconazole ocular delivery and this encourages further clinical studies.

Development and In vitro Evaluation of Nifedipine Gel Formulations for Anorectal Applications.

OBJECTIVE: Current study focuses on the formulation and characterization of lipophilic and hydrophilic gel formulations of nifedipine to treat anal fissure via anodermal application. METHODS: Lipophilic gels were prepared with Aerosil grades as gelling agents in bulk oils. Polyethylene glycols, hydroxypropyl methylcellulose, and Carbopol® 974P were used as gelling agents in water and propylene glycol for forming hydrophilic gels. The effect of repeated Freeze-Thaw Cycles (FT-C) on microstructures of the gels was investigated by examining viscosity, rheology and textural properties. Aerosil 200 containing lipophilic gels exhibited thixotropic behavior with plastic flow properties and higher viscosities. RESULT: Accordingly, their compressibility and adhesiveness increased. FT-C caused notable changes in microstructures and textural properties of the lipophilic gels excluding the formulation containing Aerosil 200-in-isopropyl myristate. Among the hydrophilic gels, the viscosity of Carbopol® 974P gels increased depending on the amount of polymer, triethanolamine and water; these gels featured plastic flow without thixotropic behavior. Their compressibility and adhesiveness were higher than other gel formulations with stable post-FT-C characteristics. The higher flux values of nifedipine were observed from water containing Carbopol® 974P gel. CONCLUSION: The results of the stability tests showed that the Carbopol® 974P gel had a longer shelf life than the Aerosil 200-in-isopropyl myristate gel.

Optimization of Microemulgel for Tizanidine Hydrochloride.

BACKGROUND: Tizanidine hydrochloride acts centrally as a muscle relaxant. It is used for the treatment of painful muscle spasm, spasticity associated with multiple sclerosis or spinal cord injury and treatment of muscle spasticity in spinal cord disease. Tizanidine hydrochloride belongs to BCS class II. It has low oral bioavailability and short halflife. Incorporating this drug in microemulgel is an excellent way to overcome problems associated with the drug. OBJECTIVES: Present research work was aimed to develop and optimize a microemulsion based gel system for tizanidine hydrochloride. METHODS: Screening of oil, surfactant and co-surfactant was carried out. Ternary phase diagram was constructed to obtain concentration range of components. The prepared microemulsion was evaluated for pH, globule size, zeta potential, conductivity, density and viscosity. 32 level factorial design was applied to study the effect of concentration of carbopol 934 and HPMC K15M on % cumulative drug release and viscosity of microemulgel using software Design Expert. Microemulgel was evaluated for pH, spreadability, viscosity, syneresis, drug content, bioadhesive strength, in-vitro as well as ex-vivo diffusion study. RESULTS: Microemulsion was prepared by using isopropyl myristate as oil, tween 80 as a surfactant and transcutol P as cosurfactant. Largest transparent microemulsion region was found with Smix ratio of 1:1. FE-SEM showed globule size 28µm for batch B1 and zeta potential was -1.27mV indicating good stability of the microemulsion. Optimised batch was F6 which showed 92% drug release within 8 hours. It followed the Korsmeyer-Peppas model. CONCLUSION: A stable, effective and elegant microemulgel formulation, exhibiting good in-vitro and ex-vivo drug release was formulated.

Preparation of microemulsion containing Lycopersicon esculentum extract: In vitro characterization and stability studies.

Lycopene, the active component of Lycopersicon esculentum species, has been reported for the protecting capabilities against ultra-violet induced skin pigmentation, antioxygen and antityrosinase activities. In the present study, extract of tomato fruit was obtained from the Lycopersicon esculentum plant using solvent system comprised of hexaneethanol-acetone. The phyto chemical active constituent lycopene was then identified by spectrophotometric technique at 470nm. Micro emulsions were developed containing different ratio of water, isopropyl myristate (oil), tween 80 and propylene glycol as surfactant and co-surfactant respectively via pseudoternary phase diagram. Various physicochemical tests were performed including globular size, conductivity, viscosity, scanning electron microscopy (SEM), refractive index (RI) and pH measurement for the formulation characterization. Results of physical and chemical stability studies showed that the micro emulsion with proportion of surfactant: co-surfactant of 2:1 (Smix) was found to be optimized formulation and with enhanced stability. Therefore, concluded that the stability of the micro emulsion was dependent on the proportions of surfactant co-surfactant, water and oil in the preparation.

Development, characterization and evaluation of ginger extract loaded microemulsion: In vitro and Ex vivo release studies.

Zingeber officinale (ginger) has been used for a long time in conventional medicine for the management of many diseases most important of which is inflammatory diseases. The aim of this study was formulation of topical microemulsion system to enhance the solubility, stability and release profile of ginger extract, as it is unstable in the presence of light, air, heat and long term storage. The solubility of ginger extract in different oils, surfactants, and cosurfactants was determined in order to find the optimal components for microemulsion. Isopropyl myristate (IPM) was selected as oil phase, tween 80 and PEG 400 were selected as surfactant and co-surfactant respectively based on highest solubility values. Pseudo-ternary phase diagram was constructed in order to find out the microemulsion region. The prepared microemulsions were evaluated for pH, viscosity, conductivity, refractive index, globular size, zeta potential, polydispersity index, ginger extract content, in-vitro and ex-vivo release profiles. The formulation GE1 showed best physicochemical properties with smallest globular size (19.75nm), highest release rate and flux value. It also showed significant (p<0.05) anti-inflammatory effect as compared to reference piroxicam drug solution. It is concluded that ginger extract can be used to develop stable microemulsion system with better skin permeation and promising antiinflammatory activity.

Transdermal transport of collagen and hyaluronic acid using water in oil microemulsion.

Collagen and hyaluronic acid (HA) are biopolymers that affect the appearance and condition of the skin. Delivery of these compounds into the skin is highly challenging since have a number of disadvantageous properties, such as high molecular weight and hydrophilicity. Here, we evaluated the transdermal penetration of low and high molecular weight collagen and HA from microemulsions. A number of microemulsion formulations, differing in the content of polymers and surfactants (i.e. penetration promoters), were used for the permeation study. In addition, a correlation was made between the composition of these microemulsions and the polymers transport efficiency. The results indicate that, microemulsions enable transdermal permeation of collagen and HA. The concentration of polymers and the solubilization capacity of microemulsions had the greatest influence on the permeation. Surprisingly, the molecular weight of polymers and the content of other components affected the size of microemulsion particles, and thus these parameters had an indirect influence on the permeation process. This study demonstrated therefore the potential therapeutic use of microemulsion with collagen and HA in improving and regenerating the barrier of aged or diseased skin.

Evaluation of miscibility and polymorphism of synthetic and natural lipids for nanostructured lipid carrier (NLC) formulations by Raman mapping and multivariate curve resolution (MCR).

Nanostructured lipid carriers (NLC) belong to youngest lipid-based nanocarrier class and they have gained increasing attention over the last ten years. NLCs are composed of a mixture of solid and liquid lipids, which solubilizes the active pharmaceutical ingredient, stabilized by a surfactant. The miscibility of the lipid excipients and structural changes (polymorphism) play an important role in the stability of the formulation and are not easily predicted in the early pharmaceutical development. Even when the excipients are macroscopically miscible, microscopic heterogeneities can result in phase separation during storage, which is only detected after several months of stability studies. In this sense, this work aimed to evaluate the miscibility and the presence of polymorphism in lipid mixtures containing synthetic (cetyl palmitate, Capryol 90®, Dhaykol 6040 LW®, Precirol ATO5® and myristyl myristate) and natural (beeswax, cocoa and shea butters, copaiba, sweet almond, sesame and coconut oils) excipients using Raman mapping and multivariate curve resolution - alternating least squares (MCR-ALS) method. The results were correlated to the macroscopic stability of the formulations. Chemical maps constructed for each excipient allowed the direct comparison among formulations, using standard deviation of the histograms and the Distributional Homogeneity Index (DHI). Lipid mixtures of cetyl palmitate/Capryol®; cetyl palmitate/Dhaykol®; myristyl myristate/Dhaykol® and myristyl myristate/coconut oil presented a single histogram distribution and were stable. The sample with Precirol®/Capryol® was not stable, although the histogram distribution was narrower than the samples with cetyl palmitate, indicating that miscibility was not the factor responsible for the instability. Structural changes before and after melting were identified for cocoa butter and shea butter, but not in the beeswax. Beeswax + copaiba oil sample was very homogenous, without polymorphism and stable over 6 months. Shea butter was also homogeneous and, in spite of the polymorphism, was stable. Formulations with cocoa butter presented a wider histogram distribution and were unstable. This paper showed that, besides the miscibility evaluation, Raman imaging could also identify the polymorphism of the lipids, two major issues in lipid-based formulation development that could help guide the developer understand the stability of the NLC formulations.

Investigation of the Compatibility of the Skin PAMPA Model with Topical Formulation and Acceptor Media Additives Using Different Assay Setups.

The Skin Parallel Artificial Membrane Permeability Assay (PAMPA) is a 96-well plate-based skin model with an artificial membrane containing free fatty acid, cholesterol, and synthetic ceramide analogs to mimic the stratum corneum (SC) barrier. The current study evaluates the compatibility of lipophilic solvents/penetration enhancer, topical emulsions containing different emulsifier systems, and organic acceptor media additives with the artificial membrane of the assay. Additionally, different assay setups (standard setup: donor in bottom plate versus modified setup: donor in top plate) were compared. Methylparaben (MP), ethylparaben (EP), and propylparaben (PP) were used as model permeants and internal standards for proper assay execution. The permeation order of the parabens (MP > EP > PP) remained the same with different lipophilic solvents, and the ranking of lipophilic solvents was comparable under standard and modified conditions (isopropyl myristate, IPM > dimethyl isosorbide, DMI ≥ propylene glycol, PG > diisopropyl adipate, DIPA). Pre-incubation of the Skin PAMPA plates with IPM, DIPA, and DMI, as well as with formulations that contain non-ionic emulsifiers, and acceptor solutions containing DMSO or EtOH (≤ 50%) for 4 h did not increase the percentage of permeated parabens in the main experiment, suggesting that those compounds do not make the artificial membrane more permeable. High-resolution mass spectrometry confirmed that acceptor solutions with ≤ 50% DMSO or EtOH do not extract stearic acid, cholesterol, and certramides at standard assay conditions. Hence, if certain constraints are considered, the Skin PAMPA model can be used as a pre-screening tool for topical formulation selection.

Formulation and Structural Study of a Biocompatible Water-in-Oil Microemulsion as an Appropriate Enzyme Carrier: The Model Case of Horseradish Peroxidase.

A novel biocompatible water-in-oil microemulsion was developed using nonionic surfactants and was investigated as a potential enzyme delivery system for pharmaceutical applications. The system was composed of isopropyl myristate/polysorbate 80 (Tween 80)/distilled monoglycerides/water/propylene glycol (PG), had a low total surfactant concentration (8.3% w/w), and was able to incorporate approximately 3% w/w aqueous phase containing horseradish peroxidase (HRP). Structural and activity aspects of the system were studied using a variety of techniques such as dynamic light scattering (DLS), electron paramagnetic resonance (EPR), and dynamic interfacial tension. The apparent hydrodynamic diameter of the empty droplets was calculated at about 37 nm. Different enzyme concentrations, ranging from 0.01 to 1.39 µM, were used for both DLS and EPR studies to effectively determine the localization of the macromolecule in the microemulsion. According to the results, for high enzyme concentrations, a participation of HRP in the surfactant monolayer of the microemulsion is evident. The number of reverse micelles in the microemulsion was defined by a theoretical model and was used to clarify how the enzyme concentration affects the number of empty and loaded reverse micelles. To assure that the system allows the enzyme to retain its catalytic activity, an oxidative reaction catalyzed by HRP was successfully carried out with the use of the model substrate 2,2'-azino-bis[3-ethylbenzothiazoline-6-sulfonic acid]. The influence of several parameters such as temperature, pH, and PG concentration was examined to optimize the reaction conditions, and a kinetic study was conducted revealing an ordered-Bi-Bi mechanism. Values of all kinetic parameters were determined. The release of the encapsulated enzyme was studied using an adequate receiver phase, revealing the effectiveness of the proposed microemulsion not only as a microreactor but also as a carrier for therapeutic biomolecules.

Electron Paramagnetic Resonance and Small-Angle X-ray Scattering Characterization of Solid Lipid Nanoparticles and Nanostructured Lipid Carriers for Dibucaine Encapsulation.

Dibucaine (DBC) is one of the most potent long-acting local anesthetics, but it also has significant toxic side effects and low water solubility. Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) have been proposed as drug-delivery systems to increase the bioavailability of local anesthetics. The purpose of the present study was to characterize SLNs and NLCs composed of cetyl palmitate or myristyl myristate, a mixture of capric and caprylic acids (for NLCs only) plus Pluronic F68 prepared for the encapsulation of DBC. We intended to provide a careful structural characterization of the nanoparticles to identify the relevant architectural parameters that lead to the desirable biological response. Initially, SLNs and NLCs were assessed in terms of their size distribution, morphology, surface charge, and drug loading. Spectroscopic techniques (infrared spectroscopy and electron paramagnetic resonance, EPR) plus small-angle X-ray scattering (SAXS) provided information on the interactions between nanoparticle components and their structural organization. The sizes of nanoparticles were in the 180 nm range with low polydispersity and negative zeta values (-25 to -46 mV). The partition coefficient of DBC between nanoparticles and water at pH 8.2 was very high (>104). EPR (with doxyl-stearate spin labels) data revealed the existence of lamellar arrangements inside the lipid nanoparticles, which was also confirmed by SAXS experiments. Moreover, the addition of DBC increased the molecular packing of both SLN and NLC lipids, indicative of DBC insertion between the lipids, in the milieu assessed by spin labels. Such structural information brings insights into understanding the molecular organization of these versatile drug-delivery systems which have already demonstrated their potential for therapeutic applications in pain control.

Peak AAA fatty acid homolog contaminants present in the dietary supplement l-Tryptophan associated with the onset of eosinophilia-myalgia syndrome.

The eosinophilia-myalgia syndrome (EMS) outbreak that occurred in the USA and elsewhere in 1989 was caused by the ingestion of Showa Denko K.K. (SD) L-tryptophan (L-Trp). "Six compounds" detected in the L-Trp were reported as case-associated contaminants. Recently the final and most statistically significant contaminant, "Peak AAA" was structurally characterized. The "compound" was actually shown to be two structural isomers resulting from condensation reactions of L-Trp with fatty acids derived from the bacterial cell membrane. They were identified as the indole C-2 anteiso (AAA1-343) and linear (AAA2-343) aliphatic chain isomers. Based on those findings, we utilized a combination of on-line HPLC-electrospray ionization mass spectrometry (LC-MS), as well as both precursor and product ion tandem mass spectrometry (MS/MS) to facilitate identification of a homologous family of condensation products related to AAA1-343 and AAA2-343. We structurally characterized eight new AAA1-XXX/AAA2-XXX contaminants, where XXX represents the integer molecular ions of all the related homologs, differing by aliphatic chain length and isomer configuration. The contaminants were derived from the following fatty acids of the bacterial cell membrane, 5-methylheptanoic acid (anteiso-C8:0) for AAA1-315; n-octanoic acid (n-C8:0) for AAA2-315; 6-methyloctanoic acid (anteiso-C9:0) for AAA1-329; n-nonanoic acid (n-C9:0) for AAA2-329; 10-methyldodecanoic acid (anteiso-C13:0) for AAA1-385; n-tridecanoic acid (n-C13:0) for AAA2-385; 11-methyltridecanoic acid (anteiso-C14:0) for AAA1-399; and n-tetradecanoic acid (n-C14:0) for AAA2-399. The concentration levels for these contaminants were estimated to be 0.1-7.9 µg / 500 mg of an individual SD L-Trp tablet or capsule The structural similarity of these homologs to case-related contaminants of Spanish Toxic Oil Syndrome (TOS) is discussed.