The potential of lipid emulsion for ocular delivery of lipophilic drugs

Novel formulations for antimicrobial peptides

Peptides in general hold much promise as a major ingredient in novel supramolecular assemblies. They may become essential in vaccine design, antimicrobial chemotherapy, cancer immunotherapy, food preservation, organs transplants, design of novel materials for dentistry, formulations against diabetes and other important strategical applications. This review discusses how novel formulations may improve the therapeutic index of antimicrobial peptides by protecting their activity and improving their bioavailability. The diversity of novel formulations using lipids, liposomes, nanoparticles, polymers, micelles, etc., within the limits of nanotechnology may also provide novel applications going beyond antimicrobial chemotherapy.

Formulation of a Novel Nanoemulsion System for Enhanced Solubility of a Sparingly Water Soluble Antibiotic, Clarithromycin

The sparingly water soluble property of majority of medicinally significant drugs acts as a potential barrier towards its utilization for therapeutic purpose. The present study was thus aimed at development of a novel oil-in-water (o/w) nanoemulsion (NE) system having ability to function as carrier for poorly soluble drugs with clarithromycin as a model antibiotic. The therapeutically effective concentration of clarithromycin, 5 mg/mL, was achieved using polysorbate 80 combined with olive oil as lipophilic counterion. A three-level three-factorial central composite experimental design was utilized to conduct the experiments. The effects of selected variables, polysorbate 80 and olive oil content and concentration of polyvinyl alcohol, were investigated. The particle size of clarithromycin for the optimized formulation was observed to be 30 nm. The morphology of the nanoemulsion was explored using transmission electron microscopy (TEM). The emulsions prepared with the optimized formula demonstrated good physical stability during storage at room temperature. Antibacterial activity was conducted with the optimized nanoemulsion NESH 01 and compared with free clarithromycin. Zone of inhibition was larger for NESH 01 as compared to that with free clarithromycin. This implies that the solubility and hence the bioavailability of clarithromycin has increased in the formulated nanoemulsion system.

Distribution of cyclosporine A in ocular tissues after topical administration of cyclosporine A cationic emulsions to pigmented rabbits

PURPOSE

The aim of this study was to compare the ocular and systemic distribution of cyclosporine A (CsA) in rabbits after the instillation of preservative-free CsA cationic and anionic emulsions.

METHODS

For the single-dose pharmacokinetic (PK) study, rabbits were instilled with 50 μL of the test material. For the multiple-dose PK study, rabbits were instilled twice daily with Restasis or once daily with NOVA22007 for 10 days. At each time point, the cornea, conjunctiva, and whole blood were harvested for CsA quantification. Ocular and systemic distribution were determined after 4 times daily instillations with 50 μL of 3H-CsA cationic and anionic emulsions for 7 days. Restasis was used as a reference in all studies.

RESULTS

Single-dose PK data demonstrated that NOVA22007 0.1% and 0.05% delivered higher CsA concentrations to the cornea than Restasis [concentration maximum (C max): 2692, 1372, and 748 ng/g, respectively] and have a better exposition (area under the curve). Conjunctival Cmax values were 1914, 696, and 849 ng/g and area under the curve values were 3984, 2796, and 2515 ng/g · h, for either dose of the cationic emulsions and Restasis, respectively. The multiple-dose PK and the 3H-CsA distribution data demonstrated that the systemic distribution after repeated instillations was low and comparable for all emulsions.

CONCLUSIONS

These data demonstrate that the CsA cationic emulsions were more effective than Restasis at delivering CsA to target tissues, thus confirming the potential advantage of cationic emulsions over anionic emulsions as vehicle for ocular drug delivery for the treatment of ocular surface diseases.

Development of O/W nanoemulsions for ophthalmic administration of timolol

After an initial screening of ingredients and production methods, nanoemulsions for ocular administration of timolol containing the drug as maleate (TM) or as ion-pair with AOT (TM/AOT) were prepared. The physico-chemical characterization of nanoemulsions, regarding mean diameter, pH, zeta potential, osmolarity, viscosity and surface tension, underlined their feasibility to be instilled into the eyes. Single components and emulsions were tested ex vivo on rabbit corneas to evaluate corneal irritation, that was measured according to opacity test. A marked decrease in corneal opacity was observed using the drug formulated in nanoemulsions rather than in aqueous solutions. Drug permeation and accumulation studies were performed on excised rabbit corneas. An increase in drug permeation through and accumulation into the corneas were observed using TM-AOT compared to TM due to an increase of lipophilicity of the drug as ion-pair. The introduction of chitosan (a positive charged mucoadhesive polymer) into emulsions allowed to increase TM permeation probably due to the interaction of chitosan with corneal epithelial cells.

Formulation optimization of a palm-based nanoemulsion system containing levodopa

Response surface methodology (RSM) was utilized to investigate the influence of the main emulsion composition; mixture of palm and medium-chain triglyceride (MCT) oil (6%–12% w/w), lecithin (1%–3% w/w), and Cremophor EL (0.5%–1.5% w/w) as well as the preparation method; addition rate (2–20 mL/min), on the physicochemical properties of palm-based nanoemulsions. The response variables were the three main emulsion properties; particle size, zeta potential and polydispersity index. Optimization of the four independent variables was carried out to obtain an optimum level palm-based nanoemulsion with desirable characteristics. The response surface analysis showed that the variation in the three responses could be depicted as a quadratic function of the main composition of the emulsion and the preparation method. The experimental data could be fitted sufficiently well into a second-order polynomial model. The optimized formulation was stable for six months at 4 °C.

Synthesis of a novel CS-g-MMCs conjugate and the inhabitation on the proliferation of Tenon's capsule fibroblasts in vitro

A novel anti-proliferative macromolecular conjugate, CS-g-MMCs, was synthesized in order to decrease the cytotoxicity of Mitomycin C (MMC) which was a traditional anti-proliferative agent of fibroblast in trabeculectomy. The structure of CS-g-MMCs was characterized by (1)H NMR, FT-IR spectroscopy and GPC analysis. The grafting degree (dg) of MMC onto chitosan (CS) was determined to be in the range of 2.8-11.3%, which could be controlled by variation of the molar ratios of MMC to oxidized chitosan (CS-CHO). In the drug release profiles of CS-g-MMCs in vitro, an initial burst followed by slow leakage was observed, and addition of acid or lysozyme obviously accelerated the MMC release. The MTS assay indicated that CS-CHO of 8 mg/ml has no cytotoxicity against human Tenon's capsule fibroblasts (HTCFs). The inhibition of HTCFs proliferation by CS-g-MMCs increased along with increasing the dg of conjugate. The CS-g-MMCs also caused the apoptosis of HTCFs and interfered in the active DNA synthesis in HTCFs. Furthermore, the expression of a-SMA at gene and protein levels were obviously lower when HTCFs were treated with CS-g-MMCs, as compared to MMC or blend of MMC/CS-CHO (p<0.05). Our results primarily demonstrated that the CS-g-MMCs conjugates have low cytotoxicity and have the effect to inhibit fibroblast proliferation.

Successfully improving ocular drug delivery using the cationic nanoemulsion, novasorb

Topical ophthalmic delivery of active ingredients can be achieved using cationic nanoemulsions. In the last decade, Novagali Pharma has successfully developed and marketed Novasorb, an advanced pharmaceutical technology for the treatment of ophthalmic diseases. This paper describes the main steps in the development of cationic nanoemulsions from formulation to evaluation in clinical trials. A major challenge of the formulation work was the selection of a cationic agent with an acceptable safety profile that would ensure a sufficient ocular surface retention time. Then, toxicity and pharmacokinetic studies were performed showing that the cationic emulsions were safe and well tolerated. Even in the absence of an active ingredient, cationic emulsions were observed in preclinical studies to have an inherent benefit on the ocular surface. Moreover, clinical trials demonstrated the efficacy and safety of cationic emulsions loaded with cyclosporine A in patients with dry eye disease. Ongoing studies evaluating latanoprost emulsion in patients with ocular surface disease and glaucoma suggest that the beneficial effects on reducing ocular surface damage may also extend to this patient population. The culmination of these efforts has been the marketing of Cationorm, a preservative-free cationic emulsion indicated for the symptomatic treatment of dry eye.

Lecithin-linker microemulsion gelatin gels for extended drug delivery

This article introduces the formulation of alcohol-free, lecithin microemulsion-based gels (MBGs) prepared with gelatin as gelling agent. The influence of oil, water, lecithin and hydrophilic and lipophilic additives (linkers) on the rheological properties and appearance of these gels was systematically explored using ternary phase diagrams. Clear MBGs were obtained in regions of single phase microemulsions (μEs) at room temperature. Increasing the water content in the formulation increased the elastic modulus of the gels, while increasing the oil content had the opposite effect. The hydrophilic additive (PEG-6-caprylic/capric glycerides) was shown to reduce the elastic modulus of gelatin gels, particularly at high temperatures. In contrast to anionic (AOT) μEs, the results suggest that in lecithin (nonionic) μEs, the introduction of gelatin “dehydrates” the μE. Finally, when the transdermal transport of lidocaine formulated in the parent μE and the resulting MBG were compared, only a minor retardation in the loading and release of lidocaine was observed.

Ocular antisense oligonucleotide delivery by cationic nanoemulsion for improved treatment of ocular neovascularization: an in-vivo study in rats and mice

The efficacy of an antisense oligonucleotide (ODN17) cationic nanoemulsion directed at VEGF-R2 to reduce neovascularization was evaluated using rat corneal neovascularization and retinopathy of prematurity (ROP) mouse models. Application of saline solution or scrambled ODN17 solution on eyes of rats led to the highest extent of corneal neovascularization. The groups treated with blank nanoemulsion or scrambled ODN17 nanoemulsion showed moderate inhibition in corneal neovascularization with no significant difference with the saline and scrambled ODN17 control solution groups, while the groups treated with ODN17 solution or Avastin® (positive ODN17 control) clearly elicited marked significant inhibition in corneal neovascularization confirming the results reported in the literature. The highest significant corneal neovascularization inhibition efficiency was noted in the groups treated with ODN17 nanoemulsion (topical and subconjunctivally). However, in the ROP mouse model, the ODN17 in PBS induced a 34% inhibition of retinal neovascularization when compared to the aqueous-vehicle-injected eyes. A significantly higher inhibition of vitreal neovascularization (64%) was observed in the group of eyes treated with ODN17 nanoemulsion. No difference in extent of neovascularization was observed between blank nanoemulsion, scrambled ODN17 nanoemulsion, vehicle or non-treated eyes. The overall results indicate that cationic nanoemulsion can be considered a promising potential ocular delivery system and an effective therapeutic tool of high clinical significance in the prevention and forthcoming treatment of ocular neovascular diseases.

Novel NSAIDs ophthalmic formulation: flurbiprofen axetil emulsion with low irritancy and improved anti-inflammation effect

The aim of this study was to design and formulate a novel low-irritant NSAIDs ophthalmic emulsion of flurbiprofen axetil (FBA), the prodrug of flurbiprofen (FB). FBA ophthalmic emulsion (FBA-EM) was prepared by high-pressure homogenization with caster oil as oil phase and tween 80 as emulsifying agent. Results from the stability evaluation suggested the protect effect of oil droplets on the stability of FBA. Compared with FBA-oil solution, the AUC(0→10h) of FB in aqueous humor administered in FBA-EMs exhibited 6.7-fold (F2), 4.5-fold (F3) and 4.6-fold (F4) increase. With the increment of oil content, the MRT also prolonged, which of FBA-EM F2-F4 were 5.14 ± 2.23, 5.73 ± 3.35 and 8.71 ± 0.94 h, respectively. No significant difference was found between the ocular bioavailability of FBA-EM F2 and 0.03% FB-Na eye drops. Ocular irritation evaluation revealed that FBA-EM F2 had better ocular biocompatibility than 0.03% FB-Na eye drops, even though the FBA concentration was up to 0.1%. Intraocular anti-inflammation effect evaluation showed that FBA-EM F2 had a quite good anti-inflammation effect. In conclusion, FBA-EM F2 with elevated FBA concentration to be 0.1% might represent a promising NSAIDs ophthalmic emulsion with low irritancy and improved anti-inflammation effect.

Ciprofloxacin surf-plexes in sub-micron emulsions: a novel approach to improve payload efficiency and antimicrobial efficacy

The aim of this study was to investigate antimicrobial efficacy and pharmacokinetic profile of ciprofloxacin (CFn) loaded oil-in-water (o/w) submicron emulsion (SE-CFn). This study emphasized on development of hydrophobic ion-pair complexes of CFn with sodium deoxycholate (SDC) [CFn-SDC], which was incorporated in the core of SE (SE-CFn-SDC). SE-CFn-SDC was characterized for globulet size (278±12 nm), zeta potential (-25.3±1 mV), viscosity (2.6±0.3 cP), transmission electron microscopy (TEM), drug entrapment and for in vitro release profile. The entrapment efficiency (EE) was significantly improved (≥80%; p≤0.05) on ion-pairing while it was merely 27.2±3.1% for free CFn. The cytotoxicity studies of formulations on J774 macrophage cells showed that more than 90±3% of cells were viable, even at high concentration (100 μg/ml). SE-CFn-SDC was further modified with cationic inducer chitosan (SE-CH-CFn-SDC), which showed almost twofold and fourfold enhancement in antimicrobial efficacy as compared to SE-CFn-SDC and SE-CFn, respectively when tested in vitro against E. coli, S. aureus, and P. aeruginosa. When tested in male Balb/c mice, the AUC(0-24h) of SE-CH-CFn-SDC (23.27±2.8 h μg/ml) was found to be 1.7-fold and 5-fold higher as compared to SE-CFn-SDC (13.17±0.88 h μg/ml) and CFn solution (4.70±0.77 h μg/ml), respectively. The study demonstrates that surfactant based ionic complex formation incorporated in surface modified submicron emulsion is a promising approach to improve payload efficiency of poorly water soluble drugs with improved antimicrobial efficacy and pharmacokinetic profile.

Efficacy and patient tolerability of travoprost BAK-free solution in patients with open-angle glaucoma and ocular hypertension

The medical treatment of glaucoma has evolved significantly over the past several decades. The main driving forces behind this evolution are the safety profiles and efficacy of these medications. Prostaglandin (PG) analogues are shown to be superior to older drugs in both efficacy and tolerability. Though there are much fewer side effects that manifest after using PG analogues, the adherence and compliance to medication regimens are surprisingly lower than expected. A commonly sited reason is the ocular irritation and inflammation with these medications. Much of this inflammation can be attributed to the preservative, benzalkonium chloride (BAK). The chronic clinical and subclinical inflammation becomes increasingly detrimental when filtration surgery fails from bleb fibrosis secondary to this hypercellularity. A BAK-free formulation of a PG analogues recently became available. BAK-free travoprost is reviewed here. It has demonstrated equal efficacy and less ocular surface toxicity than its preserved counterparts. It is expected to serve as an instrumental resource in managing ocular hypertension and glaucoma in patients who demonstrate significant sensitivity to BAK. More randomized, controlled, double-blind studies are encouraged to evaluate its improved safety and tolerability.

Stability assessment of injectable castor oil-based nano-sized emulsion containing cationic droplets stabilized by poloxamer-chitosan emulsifier films

The objectives of the present work were to prepare castor oil-based nano-sized emulsion containing cationic droplets stabilized by poloxamer-chitosan emulgator film and to assess the kinetic stability of the prepared cationic emulsion after subjecting it to thermal processing and freeze-thaw cycling. Presence of cryoprotectants (5%, w/w, sucrose +5%, w/w, sorbitol) improved the stability of emulsions to droplet aggregation during freeze-thaw cycling. After storing the emulsion at 4 degrees C, 25 degrees C, and 37 degrees C over a period of up to 6 months, no significant change was noted in mean diameter of the dispersed oil droplets. However, the emulsion stored at the highest temperature did show a progressive decrease in the pH and zeta potential values, whereas the emulsion kept at the lowest temperatures did not. This indicates that at 37 degrees C, free fatty acids were formed from the castor oil, and consequently, the liberated free fatty acids were responsible for the reduction in the emulsion pH and zeta potential values. Thus, the injectable castor oil-based nano-sized emulsion could be useful for incorporating various active pharmaceutical ingredients that are in size from small molecular drugs to large macromolecules such as oligonucleotides.

Topical and intravitreous administration of cationic nanoemulsions to deliver antisense oligonucleotides directed towards VEGF KDR receptors to the eye

Antisense oligonucleotides (ODNs) specific for VEGFR-2-(17 MER) and inhibiting HUVEC proliferation in-vitro were screened. One efficient sequence was selected and incorporated in different types of nanoemulsions the potential toxicity of which was evaluated on HUVEC and ARPE19 cells. Our results showed that below 10 microl/ml, a 2.5% mid-chain triglycerides cationic DOTAP nanoemulsion was non-toxic on HUVEC and retinal cells. This formulation was therefore chosen for further experiments. In-vitro transfection of FITC ODNs in ARPE cells using DOTAP nanoemulsions showed that nanodroplets do penetrate into the cells. Furthermore, ODNs are released from the nanoemulsion after 48 h and accumulate into the cell nuclei. In both ex-vivo and in-vivo ODN stability experiments in rabbit vitreous, it was noted that the nanoemulsion protected at least partially the ODN from degradation over 72 h. The kinetic results of fluorescent ODN (Hex) distribution in DOTAP nanoemulsion following intravitreal injection in the rat showed that the nanoemulsion penetrates all retinal cells. Pharmacokinetic and ocular tissue distribution of radioactive ODN following intravitreal injection in rabbits showed that the DOTAP nanoemulsion apparently enhanced the intraretinal penetration of the ODNs up to the inner nuclear layer (INL) and might yield potential therapeutic levels of ODN in the retina over 72 h post injection.

Chitosan-based nanostructures: a delivery platform for ocular therapeutics

Nanoscience and nanotechnology has caused important breakthroughs in different therapeutic areas. In particular, the application of nanotechnology in ophthalmology has led to the development of novel strategies for the treatment of ocular disorders. Indeed, the association of an active molecule to a nanocarrier allows the molecule to intimately interact with specific ocular structures, to overcome ocular barriers and to prolong its residence in the target tissue. Over the last decade, our group has designed and developed a delivery platform based on the polysaccharide chitosan, which suits the requirements of the topical ocular route. These nanosystems have been specifically adapted for the delivery of hydrophilic and lipophilic drugs and also polynucleotides onto the eye surface. The results collected up until now suggest the potential of this delivery platform and the subsequent need of a full preclinical evaluation in order to satisfy the specific regulatory demands of this mode of administration.

Formulation of multifunctional oil-in-water nanosized emulsions for active and passive targeting of drugs to otherwise inaccessible internal organs of the human body

Oil-in-water (o/w) type nanosized emulsions (NE) have been widely investigated as vehicles/carrier for the formulation and delivery of drugs with a broad range of applications. A comprehensive summary is presented on how to formulate the multifunctional o/w NE for active and passive targeting of drugs to otherwise inaccessible internal organs of the human body. The NE is classified into three generations based on its development over the last couple of decades to make ultimately a better colloidal carrier for a target site within the internal and external organs/parts of the body, thus allowing site-specific drug delivery and/or enhanced drug absorption. The third generation NE has tremendous application for drug absorption enhancement and for 'ferrying' compounds across cell membranes in comparison to its first and second generation counterparts. Furthermore, the third generation NE provides an interesting opportunity for use as drug delivery vehicles for numerous therapeutics that can range in size from small molecules to macromolecules.

The role of difluprednate ophthalmic emulsion in clinical practice

The mainstay in the treatment of ocular inflammation, either post-surgical or endogenous, is the use of steroids. While these agents effectively address inflammation, they are not without their risks, including ocular hypertension and acceleration of cataract formation. The most notorious culprits are the strong steroids, such as prednisolone acetate and betamethasone. This review aims to cover the biochemistry and drug development of difluprednate, a novel synthetic strong steroid emulsion. In vivo pharmacokinetics as well as ocular distribution and metabolism are discussed, followed by a comprehensive summary of phase I, II, and III clinical trials evaluating safety and efficacy in patients suffering from postoperative inflammation or anterior uveitis. The objective is to provide an increased familiarity with this newly approved medication as a welcome addition to the ophthalmologist’s armamentarium.

Nanoemulsion as a potential ophthalmic delivery system for dorzolamide hydrochloride

Dilutable nanoemulsions are potent drug delivery vehicles for ophthalmic use due to their numerous advantages as sustained effect and high ability of drug penetration into the deeper layers of the ocular structure and the aqueous humor. The aim of this article was to formulate the antiglaucoma drug dorzolamide hydrochloride as ocular nanoemulsion of high therapeutic efficacy and prolonged effect. Thirty-six systems consisting of different oils, surfactants, and cosurfactants were prepared and their pseudoternary-phase diagrams were constructed by water titration method. Seventeen dorzolamide hydrochloride nanoemulsions were prepared and evaluated for their physicochemical and drug release properties. These nanoemulsions showed acceptable physicochemical properties and exhibited slow drug release. Draize rabbit eye irritation test and histological examination were carried out for those preparations exhibiting superior properties and revealed that they were nonirritant. Biological evaluation of dorzolamide hydrochloride nanoemulsions on normotensive albino rabbits indicated that these products had higher therapeutic efficacy, faster onset of action, and prolonged effect relative to either drug solution or the market product. Formulation of dorzolamide hydrochloride in a nanoemulsion form offers, thus, a more intensive treatment of glaucoma, a decrease in the number of applications per day, and a better patient compliance compared to conventional eye drops.

Mucoadhesive effect of thiolated PEG stearate and its modified NLC for ocular drug delivery

This study was to develop a thiolated non-ionic surfactant, cysteine-polyethylene glycol stearate (Cys-PEG-SA), for the assembling of nanoparticulate ocular drug delivery system with mucoadhesive property. Cys-PEG-SA was synthesized in two steps reaction involving a new derivative intermediate formation of p-nitrophenylcarbonyl-PEG-SA (pNP-PEG-SA). Up to 369.43+/-25.54 mumol free thiol groups per gram of the conjugates was reached. The nanostructured lipid carrier (NLC) loaded cyclosporine A (CyA) was prepared by melt-emulsification method. The mucoadhesive NLC (Cys-NLC) was obtained by incubating NLC emulsion with Cys-PEG-SA. The mucoadhesive properties of these nanocarriers were examined by using mucin particles method. The particle size or zeta potential of the porcine mucin particles were changed with the added concentration of Cys-PEG-SA, and the disulphide bond breaker cysteine significantly reduced the adhesion of Cys-NLC to mucin particles (P<0.05), whereas PEG-SA and NLC did not alternate the properties of the mucin particles. When Cys-NLC was administered topically to the rabbit eye, the encapsulated cyclosporine was found to remain on the ocular surface in the cul-de-sac for up to 6 h, both precorneal retention time and concentration were dramatically increased (P<0.05), compared with the NLC without thiomer modification.

Polyoxyethylated nonionic surfactants and their applications in topical ocular drug delivery

Topical dosing of ophthalmic drugs to the eye is a widely accepted route of administration because of convenience, ease of use, and non-invasiveness. However, it has been well recognized that topical ocular delivery endures a low bioavailability due to the anatomical and physiological constraints of the eye which limit drug absorption from the pre-corneal surface. Nonionic surfactants as versatile functional agents in topical ocular drug delivery systems are uniquely suited to meet the challenges through their potential ability to increase bioavailability by increasing drug solubility, prolonging pre-corneal retention, and enhancing permeability. This review attempts to place in perspective the importance of polyoxyethylated nonionic surfactants in the design and development of topical ocular drug delivery systems by assessing their compatibility with common ophthalmic inactive ingredients, their impact on product stability, and their roles in facilitating ocular drugs to reach the target sites.

Niosome-encapsulated gentamicin for ophthalmic controlled delivery

The objective of the present research was to investigate the feasibility of using non-ionic surfactant vesicles (niosomes) as carriers for the ophthalmic controlled delivery of a water soluble local antibiotic; gentamicin sulphate. Niosomal formulations were prepared using various surfactants (Tween 60, Tween 80 or Brij 35), in the presence of cholesterol and a negative charge inducer dicetyl phosphate (DCP) in different molar ratios and by employing a thin film hydration technique. The ability of these vesicles to entrap the studied drug was evaluated by determining the entrapment efficiency %EE after centrifugation and separation of the formed vesicles. Photomicroscopy and transmission electron microscopy as well as particle size analysis were used to study the formation, morphology and size of the drug loaded niosomes. Results showed a substantial change in the release rate and an alteration in the %EE of gentamicin sulphate from niosomal formulations upon varying type of surfactant, cholesterol content and presence or absence of DCP. In-vitro drug release results confirmed that niosomal formulations have exhibited a high retention of gentamicin sulphate inside the vesicles such that their in vitro release was slower compared to the drug solution. A preparation with 1:1:0.1 molar ratio of Tween 60, cholesterol and DCP gave the most advantageous entrapment (92.02% +/- 1.43) and release results (Q(8h) = 66.29% +/- 1.33) as compared to other compositions. Ocular irritancy test performed on albino rabbits, showed no sign of irritation for all tested niosomal formulations.

Emulsions of oil from Adenanthera pavonina L. seeds and their protective effect

In our previous study, we developed very stable formulations of submicron oil-in-water emulsions from Adenanthera pavonina L. (family Leguminosae, subfamily Mimosoideae) seed oil, stabilised with soybean lecithin (SPC). Continuing our research, we introduced an additional co-emulsifier, Tween 80, to those formulations in order to decrease the size of the emulsion particles and improve their stability. Formulations with a mean particle size ranging from 43.6 to 306.5 nm and a negative surface charge from -45.3 to -28.5 mV were obtained. Our stability experiments also revealed that most of the tested formulations had a very good degree of stability over a 3-month storage period, both at 4 degrees C and at room temperature. Since many intravenous injectable drugs exhibit lytic activity against erythrocytes, we examined this activity for the emulsion form of cardol, a natural compound with already proven hemolytic properties. The incorporation of this agent into the emulsion caused an evident decrease in hemolytic activity (97-99%). This highly protective effect, observed against sheep erythrocytes, was independent of both the composition and the particle size of the emulsions used. Our studies suggest that nonionic surfactant/phospholipid-based emulsions containing this edible oil of A. pavonina L. may be useful as an alternative formulation matrix for pharmaceutical, nutritional or cosmetic applications of otherwise membrane-acting components.

Validation of an isocratic LC method for determination of quercetin and methylquercetin in topical nanoemulsions

The aim of this study was to validate an isocratic LC method for the quantification of either quercetin (Q) or methylquercetin (MQ) incorporated in topical nanoemulsions. The analyses were performed at room temperature on a reversed-phase C(18) column using a mobile phase composed of methanol/water (70:30, v/v) and trifluoracetic acid 0.1% at 0.8 mL min(-1). The detection was carried out on a UV detector at 368 or 354 nm for Q and MQ, respectively. The linearity, in the range of 0.15-1.5 microg/mL, presented a determination coefficient (r(2)) higher than 0.99, calculated by the least square method for both flavonoids. No interferences from the excipients (egg-lecithin or octyldodecanol) were detected. The R.S.D. values for intra- and inter-day precision experiments were lower than 2% for both flavonoids. The recovery ranged from 98.9% to 103.46% for Q and from 98.9% to 102.92% for MQ.

Anti-HER2 Cationic Immunoemulsion as a Potential Targeted Drug Delivery System for the Treatment of Prostate Cancer

Present management of metastatic prostate cancer, which includes hormonal therapy, chemotherapy, and radiotherapy, are frequently palliative. Taxanes, and specifically docetaxel, are being extensively investigated to improve the survival of metastatic prostate cancer patients. Although paclitaxel exhibits a wide spectrum of antitumor activity, its therapeutic application is limited, in part, due to its low water solubility that necessitates the use of Cremophor EL, which is known to induce hypersensitivity reactions. Therefore, the objective of this present study was to assess the efficiency of paclitaxel palmitate-loaded anti-HER2 immunoemulsions, a targeted drug delivery system based on cationic emulsion covalently linked to anti-HER2 monoclonal antibody (Herceptin), in a well-established in vivo pharmacologic model of metastatic prostate cancer that overexpresses the HER2 receptor. It was clearly noted that the cationic emulsion and immunoemulsion did not activate the complement compared with the commercial and paclitaxel palmitate hydroalcoholic formulations. In addition, 10 mg/kg of paclitaxel palmitate-loaded immunoemulsion once weekly over 3 weeks inhibits the tumor growth in severe combined immunodeficient mice much more than the cationic emulsion (P < 0.05) and the paclitaxel palmitate formulation (P < 0.01). The histopathologic analysis suggested a therapeutic improvement trend in favor of the immunoemulsion. However, there was no significant difference in antimetastatic activity between the emulsion and the immunoemulsion despite the affinity of the immunoemulsion towards the HER2 receptor. Although the tumor growth was not fully inhibited, the actual results are encouraging and may lead to an improved therapeutic strategy of metastatic prostate cancer treatment.

Arnold tongues in a microfluidic drop emitter

The Letter reports an experimental study of microfluidic droplets produced in T junctions and subjected to a local periodic forcing. Synchronized and quasiperiodic regimes--organized into Arnold tongues and devil staircases--are reported for the first time for a system dedicated to drop emission. The nature of the dynamical regime controls the droplet characteristics. These phenomena are mostly controlled by the characteristics of the forcing and the flow conditions.

The design and evaluation of a novel targeted drug delivery system using cationic emulsion-antibody conjugates

In an attempt to design a targeted drug delivery system to tumors' over-expressing H-ferritin specifically recognized by a monoclonal antibody, AMB8LK, a cationic emulsion - AMB8LK conjugate was prepared. A novel cross-linker molecule bearing maleimide group was synthesized and added to cationic emulsion formulation for AMB8LK Fab' fragment covalent coupling. NMR spectroscopy confirmed the cross-linker synthesis and the preservation of the active maleimide function. SDS gel-electrophoresis results corroborated the formation of the Fab' fragment. Different densities of Fab' fragments (10-200 Fab'/oil droplet) were conjugated to emulsion droplet interface and no changes in the physico-chemical properties were observed ( approximately 120 nm size and zeta potential of approximately +30 mV). The coupling efficiency ranged from 55% to 70% and was visualized by TEM showing gold particles attached to the droplet interface. Cell culture studies demonstrated specific binding to cells as confirmed by the occurrence of the marked reduction in binding when free AMB8LK Mab was incubated before adding the AMB8LK-emulsion conjugate to the cells. The coupling of AMB8LK Fab' fragment to the cationic emulsion increased the cells uptake by 50% as compared to non-conjugated respective cationic emulsion. Appropriate conditions were, thus, identified for coupling AMB8LK Fab' fragment to cationic emulsion without altering the specificity and affinity of the Mab fragment to the tumor antigen.

Formulation of an ophthalmic lipid emulsion containing an anti-inflammatory steroidal drug, difluprednate

Preparation of oil-in-water (o/w) type lipid emulsion is one of the approaches to formulate drugs that are poorly water-soluble but can be dissolved in the oil phase of the emulsions. A synthetic glucocorticoid medicine, difluprednate (DFBA), is a water-insoluble compound. We formulated DFBA (0.05%, w/v) ophthalmic lipid emulsion containing 5.0% (w/v) caster oil and 4.0% (w/v) polysorbate 80. The appearance of the emulsion was blue and translucent lipid emulsion, and the median particle size of the lipid emulsion was 104.4 nm. Neither separation nor change in particle size was observed after 6 months at 40 degrees C. Furthermore, when compared with DFBA (0.05%, w/v) ophthalmic suspension, the lipid emulsion showed 5.7-fold higher concentration of DFB that was an active metabolite of DFBA in aqueous humor at 1h after instillation. Ophthalmic lipid emulsion enhances the intraocular penetration of drugs, and it is useful as a delivery system for the ophthalmic preparations of lipophilic drugs.

Oil-in-water lipid emulsions: implications for parenteral and ocular delivering systems

Lipid emulsions (LEs) are heterogenous dispersions of two immiscible liquids (oil-in-water or water-in-oil) and they are subjected to various instability processes like aggregation, flocculation, coalescence and hence eventual phase separation according to the second law of thermodynamics. However, the physical stability of the LE can substantially be improved with help of suitable emulsifiers that are capable of forming a mono- or multi-layer coating film around the dispersed liquid droplets in such a way to reduce interfacial tension or to increase droplet-droplet repulsion. Depending on the concentrations of these three components (oil-water-emulsifier) and the efficiency of the emulsification equipments used to reduce droplet size, the final LE may be in the form of oil-in-water (o/w), water-in-oil (w/o), micron, submicron and double or multiple emulsions (o/w/o and w/o/w). The o/w type LEs (LE) are colloidal drug carriers, which have various therapeutic applications. As an intravenous delivery system it incorporates lipophilic water non-soluble drugs, stabilize drugs that tend to undergo hydrolysis and reduce side effects of various potent drugs. When the LE is used as an ocular delivery systems they increase local bioavailability, sustain the pharmacological effect of drugs and decrease systemic side effects of the drugs. Thus, the rationale of using LE as an integral part of effective treatment is clear. Following administration of LE through these routes, the biofate of LE associated bioactive molecules are somehow related to the vehicles disposition kinetics inside blood or eyeball. However, the LE is not devoid from undergoing various bio-process while exerting their efficacious actions. The purpose of this review is therefore to give an implication of LE for parenteral and ocular delivering systems.