Flurbiprofen, S(+), eyedrops: formulation, enantiomeric assay, shelf-life and pharmacology

Delivery of melittin-loaded niosomes for breast cancer treatment: an in vitro and in vivo evaluation of anti-cancer effect

Background

Melittin, a peptide component of honey bee venom, is an appealing candidate for cancer therapy. In the current study, melittin, melittin-loaded niosome, and empty niosome had been optimized and the anticancer effect assessed in vitro on 4T1 and SKBR3 breast cell lines and in vivo on BALB/C inbred mice. "Thin-layer hydration method" was used for preparing the niosomes; different niosomal formulations of melittin were prepared and characterized in terms of morphology, size, polydispersity index, encapsulation efficiency, release kinetics, and stability. A niosome was formulated and loaded with melittin as a promising drug carrier system for chemotherapy of the breast cancer cells. Hemolysis, apoptosis, cell cytotoxicity, invasion and migration of selected concentrations of melittin, and melittin-loaded niosome were evaluated on 4T1 and SKBR3 cells using hemolytic activity assay, flow cytometry, MTT assay, soft agar colony assay, and wound healing assay. Real-time PCR was used to determine the gene expression. 40 BALB/c inbred mice were used; then, the histopathology, P53 immunohistochemical assay and estimate of renal and liver enzyme activity for all groups had been done.

Results

This study showed melittin-loaded niosome is an excellent substitute in breast cancer treatment due to enhanced targeting, encapsulation efficiency, PDI, and release rate and shows a high anticancer effect on cell lines. The melittin-loaded niosome affects the genes expression by studied cells were higher than other samples; down-regulates the expression of Bcl2, MMP2, and MMP9 genes while they up-regulate the expression of Bax, Caspase3 and Caspase9 genes. They have also enhanced the apoptosis rate and inhibited cell migration, invasion in both cell lines compared to the melittin samples. Results of histopathology showed reduce mitosis index, invasion and pleomorphism in melittin-loaded niosome. Renal and hepatic biomarker activity did not significantly differ in melittin-loaded niosome and melittin compared to healthy control. In immunohistochemistry, P53 expression did not show a significant change in all groups.

Conclusions

Our study successfully declares that melittin-loaded niosome had more anti-cancer effects than free melittin. This project has demonstrated that niosomes are suitable vesicle carriers for melittin, compare to the free form.

An investigation to elucidate the factors dictating the crystal structure of seven ammonium carboxyl-ate mol-ecular salts

The crystal structures of seven ammonium carboxyl-ate salts are reported, namely (RS)-1-phenyl-ethan-1-aminium isonicotinate, C8H12N+·C6H4N1O2-, (I), (RS)-1-phenyl-ethan-1-aminium flurbiprofenate [or 2-(3-fluoro-4-phenyl-phen-yl)propano-ate], C8H12N+·C15H12FO2-, (II), (RS)-1-phenyl-ethan-1-aminium 2-chloro-4-nitro-benzoate, C8H12N+·C7H3ClNO4-, (III), (RS)-1-phenyl-ethan-1-aminium 4-iodo-benzoate, C8H12N+·C7H4IO2-, (IV), (S)-1-cyclo-hexyl-ethan-1-aminium 2-chloro-4-nitro-benzoate, C8H18N+·C7H3ClNO4-, (V), 2-(cyclo-hex-1-en-1-yl)ethan-1-aminium 4-bromo-benzoate, C8H16N+·C7H4BrO2-, (VI), and (S)-1-cyclo-hexyl-ethan-1-aminium 4-bromo-benzoate, C8H18N+·C7H4BrO2-, (VII). Salts (II) to (VII) feature three N+-H⋯O- hydrogen bonds, which form one-dimensional hydrogen-bonded ladders. Salts (II), (III), (IV), (V) and (VII) have a type II ladder system despite the presence of halogen bonding and other inter-molecular inter-actions, whereas (VI) has a type III ladder system. Salt (I) has a unique hydrogen-bonded system of ladders, featuring both N+-H⋯O- and N+-H⋯N hydrogen bonds owing to the presence of the pyridine functional group. The presence of an additional hydrogen-bond acceptor on the carboxyl-ate cation disrupts the formation of the ubiquitous type II and III ladder found predominately in ammonium carboxyl-ate salts. Halogen bonding, however, has no influence on their formation.

Niosomes: a review of their structure, properties, methods of preparation, and medical applications

Target-specific drug-delivery systems for the administration of pharmaceutical compounds enable the localization of drugs to diseased sites. Various types of drug-delivery systems utilize carriers, such as immunoglobulins, serum proteins, synthetic polymers, liposomes, and microspheres. The vesicular system of niosomes, with their bilayer structure assembled by nonionic surfactants, is able to enhance the bioavailability of a drug to a predetermined area for a period. The amphiphilic nature of niosomes promotes their efficiency in encapsulating lipophilic or hydrophilic drugs. Other additives, such as cholesterol, can be used to maintain the rigidity of the niosomes’ structure. This narrative review describes fundamental aspects of niosomes, including their structural components, methods of preparation, limitations, and current applications to various diseases.

Pre-absorption physicochemical compatibility assessment of 8-drug metabolic cocktail

A comprehensive 8-drug metabolic cocktail was designed to simultaneously target 6 Cytochrome P450 enzymes and 2 membrane transporters. This study aimed to assess the pre-absorption risk of this new metabolic cocktail which contained metoprolol, caffeine, midazolam, pravastatin, flurbiprofen, omeprazole, digoxin and montelukast. This paper describes a systematic approach to understand whether the co-administration of the 8 selected drug products, i.e., the physical mixing of these products in the human gastro-intestinal environment, will create any issue that may interfere with the individual drug dissolution which in turns modify the total amount or timing of their availability for absorption. The evaluation consisted of two steps. An initial evaluation was based on theoretical understanding of the physicochemical properties of the drugs and the gastro intestinal environment, followed by in vitro dissolution tests. The results indicated that the designer 8-drug cocktail has acceptable pre-absorption compatibility when dosed simultaneously, and recommended the progression of the cocktail into clinical validation study.

Growth and shrinkage of pluronic micelles by uptake and release of flurbiprofen: variation of pH

The micellization of Pluronic triblock copolymers (P103, P123, and L43) in the presence of flurbiprofen at different pH was studied by small-angle neutron scattering (SANS), pulsed-field gradient stimulated-echo nuclear magnetic resonance (PFGSE-NMR), and surface tension measurements. Addition of flurbiprofen to the Pluronic at low pH leads to an increase in the fraction of micellization, aggregation number, and the core radius of the micelles. However, changing the pH to above the pKa of flurbiprofen in an ethanol/water mixture (∼6.5) reduces the fraction of micellization and results in a weaker interaction between the drug and micelles due to the increased drug solubility in aqueous solution.

Role of hydroxypropyl-β-cyclodextrin on freeze-dried and gamma-irradiated PLGA and PLGA-PEG diblock copolymer nanospheres for ophthalmic flurbiprofen delivery

Poly(D,L-lactide-co-glycolide) and poly(D,L-lactide-co-glycolide) with poly(ethylene glycol) nanospheres (NSs) incorporating flurbiprofen (FB) were freeze-dried with several cryoprotective agents and sterilized by γ-irradiation. Only when 5.0% (w/v) hydroxypropyl-β-cyclodextrin (HPβCD) was used, a complete resuspension by manual shaking and almost identical particle size of the NSs was obtained after freeze-drying. In vitro drug release and ex vivo corneal permeation of NSs with and without HPβCD were evaluated. The presence of HPβCD resulted in a reduction of burst effect, providing a more sustained release of the drug. A significant decrease in the FB transcorneal permeation of NSs containing HPβCD was obtained, related to the slower diffusion of FB observed in the in vitro results. The uptake mechanism of the NSs was examined by confocal microscopy, suggesting that NSs penetrate corneal epithelium through a transcellular pathway. Ocular tolerance was assessed in vitro and in vivo by the Eytex™ and Draize test, respectively. Long-term stability studies revealed that γ-irradiated NSs stored as freeze-dried powders maintained their initial characteristics. Stability studies of the resuspended NSs after 3 months of storage in the aqueous form showed that NSs were stable at 4°C, while formulations stored at 25°C and 40°C increased their initial particle size.

Eudragit® microparticles as a possible tool for ophthalmic administration of acyclovir

This paper describes the production and characterization of polyacrylic polymer (Eudragit RL, RS and NE) microparticles by spray drying method. Microparticles were designed for ophthalmic administration of acyclovir. Microparticle morphology was characterized by optical and electron microscopy. The release kinetics of the drug from microspheres were determined by a dialysis method. The spray drying method described allows the production of microparticles with acceptable encapsulation efficiency and appropriate dimensional characteristics for ophthalmic administration. Release profile data indicate that acyclovir is released from microparticles in a controlled manner. In addition the release pattern of the drug is influenced by the type of Eudragit used for microparticle production. Moreover the plaque reduction efficiency of acyclovir containing microparticles (except for RS/NE microspheres) is comparable to that displayed by the free drug. Finally our results suggest that acyclovir containing microparticles could represent an interesting system for the release of this antiviral drug at the eye site.

Topical ocular delivery of NSAIDs

In ocular tissue, arachidonic acid is metabolized by cyclooxygenase to prostaglandins which are the most important lipid derived mediators of inflammation. Presently nonsteroidal anti-inflammatory drugs (NSAIDs) which are cyclooxygenase (COX) inhibitors are being used for the treatment of inflammatory disorders. NSAIDs used in ophthalmology, topically, are salicylic-, indole acetic-, aryl acetic-, aryl propionic- and enolic acid derivatives. NSAIDs are weak acids with pKa mostly between 3.5 and 4.5, and are poorly soluble in water. Aqueous ophthalmic solutions of NSAIDs have been made using sodium, potassium, tromethamine and lysine salts or complexing with cyclodextrins/solubilizer. Ocular penetration of NSAID demands an acidic ophthalmic solution where cyclodextrin could prevent precipitation of drug and minimize its ocular irritation potential. The incompatibility of NSAID with benzalkonium chloride is avoided by using polysorbate 80, cyclodextrins or tromethamine. Lysine salts and alpha-tocopheryl polyethylene glycol succinate disrupt corneal integrity, and their use requires caution. Thus a nonirritating ophthalmic solution of NSAID could be formulated by dissolving an appropriate water-soluble salt, in the presence of cyclodextrin or tromethamine (if needed) in mildly acidified purified water (if stability permits) with or without benzalkonium chloride and polyvinyl alcohol. Amide prodrugs met with mixed success due to incomplete intraocular hydrolysis. Suspension and ocular inserts appear irritating to the inflamed eye. Oil drop may be a suitable option for insoluble drugs and ointment may be used for sustained effect. Recent studies showed that the use of colloidal nanoparticle formulations and the potent COX 2 inhibitor bromfenac may enhance NSAID efficacy in eye preparations.

Chirality in ocular agents

PURPOSE OF REVIEW

To review the role of chirality in current ocular pharmacology. The importance of stereo-isomeric purity has frequently been emphasized in recent years. Development of chirally pure medications can lead to improved efficacy and side-effect profiles. Practitioners prescribing ocular agents may benefit from understanding the effects of chirality in their evaluation of old and new medications.

RECENT FINDINGS

Chirality can affect multiple classes of ocular agents. Although the ways in which stereo-isomers influence the properties of a drug differ, this review illustrates the benefit of knowledge of individual isomers' effects in clinical decision making. The variety of possible effects stereo-isomers produce further underlines the importance of purification and in-depth analysis of chiral compounds.

SUMMARY

Many important agents exist as a mixture of two different stereoisomers. Both isomers may produce a pharmacological effect; however, these effects may be different from one another and one isomer may even give a result opposite from the desired pharmacological effect. Here we examine published findings on ocular medications relating to their chiral nature and summarize the possible ways chirality affects the activity of a few ocular agents. Many more ocular medications have not been investigated to ascertain their chiral properties. This review adds to the recent emphasis on investigating stereo-isomers for individual selectivity of beneficial and adverse profiles.

Flurbiprofen loaded biodegradable nanoparticles for ophtalmic administration

Poly(lactic/glycolic) acid nanoparticles incorporating flurbiprofen (FB) were prepared by the solvent displacement technique using poloxamer 188 as a stabilizer to improve the availability of the drug for the prevention of the inflammation caused by ocular surgery. A 2(3) + star design was applied to investigate the influence of several factors such as the pH of the aqueous phase, the initial concentration of the stabilizer, and the drug used to prepare the nanoparticles (NPs) on the physicochemical properties (particle size analysis, zeta potential, and drug loading efficiency) of the colloidal system. The best formulations were those prepared at pH 3.5 with a concentration of 1.5 mg/mL of FB and 10 or 20 mg/mL of poloxamer 188. These formulations showed an appropriate average size for ophthalmic administration (232.8 and 277.6 nm, respectively) and a good yield of entrapment efficiency (94.60% and 93.55%, respectively). The release behavior of FB from the developed NPs was complete and exhibited a biphasic pattern. Formulations did not show toxicity on ocular tissues. In vivo anti-inflammatory efficacy was assessed in the rabbit eye after topical instillation of sodium arachidonate (SA). A higher decrease of the SA-induced inflammation was obtained for the NP formulations.

Constitutive cyclooxygenase-1 and induced cyclooxygenase-2 in isolated human iris inhibited by S(+) flurbiprofen

The purpose of the present study was to characterize the isoforms of cyclooxygenase (COX) in the human iris before and after stimulation with lipopolysaccharide (LPS) and to determine the selectivity of the nonsteroidal anti-inflammatory drug (NSAID), S(+) flurbiprofen, for inhibition of COX-1 and COX-2 in homogenates of this tissue. Spotblots were made of extracts of human iris in the absence and presence of LPS plus acetylsalicylic acid (aspirin). After reacting with anti-COX-1 and anti-COX-2 immunoglobulin G, the presence of both immunoreactive COX enzymes was substantiated using an indirect immunoperoxidase method. Authentic COX-1 and COX-2 were used as controls. Using an enzyme immune assay (EIA), the production of prostaglandin E2 (PGE2) was quantified in tissue homogenates of human iris under the same conditions as described above. S(+) flurbiprofen was added to tissue homogenates in order to determine the inhibitory effect on PGE2 production. Half maximal inhibitory concentrations (IC50) of S(+) flurbiprofen for the PGE2 production in the tissue homogenates were determined from concentration inhibition curves. The selectivity of S(+) flurbiprofen for inhibition of COX-1 was expressed as the ratio of IC50 for COX-2/COX-1. Spotblots of nonstimulated iris-extracts showed positive staining for COX-1 immunoreactivity (-ir) only. After incubation with LPS plus acetylsalicylic acid, positive staining was observed for both COX-1-ir and COX-2-ir. Concentrations of PGE2 released from homogenates of untreated iris varied from 1.5-4 ng/ml, and of LPS-stimulated tissue from 10-20 ng/ml of assay mixture. S(+) flurbiprofen inhibited PGE2 production of untreated tissue homogenates at an IC50 of 8 x 10(-10) M whereas, in the stimulated tissue, IC50 was found to be 3 x 10(-6) M. The selectivity of S(+) flurbiprofen for inhibition of constitutively present COX-1, relative to the inhibition of induced COX-2, was 3,600. Our results indicate that specific expression of COX isoforms in normal human iris was substantiated at the protein level by immunoreaction on spotblots. COX-1 represents the constitutively present enzyme, and COX-2 appears after stimulation with LPS. At the functional level, S(+) flurbiprofen possesses a specificity for COX-1 in inhibiting PGE2 production.

Flurbiprofen and enantiomers in ophthalmic solution tested as inhibitors of prostanoid synthesis in human blood

The purpose of this study was to assess the selectivity and potency of the nonsteroidal anti-inflammatory drug (NSAID), flurbiprofen, and its enantiomers in their inhibition of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2). An assay was used with freshly drawn, heparinized human whole blood, incubated with 25 microM calcium ionophore A23187 during 60 min to produce thromboxane B2 (TXB2) by activity of COX-1 in platelets. Incubation with E. coli lipopolysaccharide (LPS) during 24 hr produced prostaglandin E2 (PGE2) by induction of COX-2 in monocytes, suppressing any possible contribution of COX-1 activity by the addition of acetylsalicylic acid. Concentration inhibition curves were determined with racemic, S(+), and R(-) flurbiprofen in final concentrations ranging from 10(-3) to 10(-10) M. The stereoselectivity of S(+) flurbiprofen vs. R(-) flurbiprofen, expressed as the reciprocal of the ratio of the concentrations giving 50% inhibition (IC50), is 340 for COX-1 and 56 for COX-2. The selectivity for COX-1 vs. COX-2, expressed as the reciprocal ratio of the IC50, was 32 for racemic, 16 for S(+), and 5.3 for R(-) flurbiprofen. Meloxicam in the same assay showed COX-2 selectivity with a ratio of 0.19.