Chiral resolution of (±)-flurbiprofen using molecularly imprinted hydrazidine-modified cellulose microparticles

Flurbiprofen (FP) is one of the non-steroidal anti-inflammatory drugs (NSAIDs) commonly used to treat arthritic conditions. FP has two enantiomers: S-FP and R-FP. S-FP has potent anti-inflammatory effects, while R-FP has nearly no such effects. Herein, molecularly imprinted microparticles produced from hydrazidine-cellulose (CHD) biopolymer for the preferential uptake of S-FP and chiral resolution of (±)-FP were developed. First, cyanoethylcellulose (CECN) was synthesized, and the -CN units were transformed into hydrazidine groups. The developed CHD was subsequently shaped into microparticles and ionically interacted with the S-FP enantiomer. The particles were then imprinted after being cross-linked with glutaraldehyde, and then the S-FP was removed to provide the S-FP enantio-selective sorbent (S-FPCHD). After characterization, the optimal removal settings for the S- and R-FP enantiomers were determined. The results indicated a capacity of 125 mg/g under the optimum pH range of 5-7. Also, S-FPCHD displayed a noticeable affinity toward S-FP with a 12-fold increase compared to the R-FP enantiomer. The chiral resolution of the (±)-FP was successfully attempted using separation columns, and the outlet sample of the loading solution displayed an enantiomeric excess (ee) of 93 % related to the R-FP, while the eluent solution displayed an ee value of 95 % related to the S-FP.

Discovery of (S)-flurbiprofen-based novel azine derivatives as prostaglandin endoperoxide synthase-II inhibitors: Synthesis, in-vivo analgesic, anti-inflammatory activities, and their molecular docking

The anti-inflammatory and analgesic drugs currently used are associated with several adverse effects and found to be highly unsafe for long-term use. Currently, nineteen novel bis-Schiff base derivatives (1-19) of flurbiprofen have been designed, prepared and assessed for in-vivo analgesic, anti-inflammatory and in vivo acute toxicity evaluation. The structures of the acquired compounds were deduced through modern spectroscopic techniques including HR-ESI-MS, 13C-, and 1H NMR. Amongst the series, compounds 7, 9, and 10 attributed potent activities with 93.89, 92.50, and 90.47% decreased edema, respectively compared to flurbiprofen (90.01%), however, compounds 11 and 15 exhibited significant activity of 90.00% decrease. Out of them, fourteen compounds (1-6, 8, 12-14, and 16-19) displayed good activity in the range of 68.96-86.95%. In case of an analgesic study, all the derivatives significantly (p 0.001) increased the pain threshold time particularly compound 7 had the best analgesic effect (24 ± 2.08 s) in comparison with flurbiprofen (21.66 ± 2.02 s) using hot plate test. Similarly, in the acetic acid-induced writhing test, compound 7 determined a potent inhibitory effect (60.47 %) close to flurbiprofen (59.28%). All the synthesized derivatives were found safe up to the dose of 30 mg/kg, in acute toxicity study. On a molecular scale, the synthesized compounds were modeled through a ligand-based pharmacophore study and molecular docking to have insight into the different possible interactions leading to high inhibition levels against the COX-2 enzyme.

Quality by design (QbD) approach to develop fast-dissolving tablets using melt-dispersion paired with surface-adsorption method: formulation and pharmacokinetics of flurbiprofen melt-dispersion granules

Developing amorphous solid dispersions with good flow properties is always challenging for formulation scientists to convert into tablets. Hence, the present study investigates the impact of the combination of melt-dispersion and surface-adsorption methods to prepare melt-dispersion granules with enhanced dissolution rate and flow properties. This study covers the formulation and pharmacokinetic study of fast-dissolving flurbiprofen tablets using PEG 6000 (hydrophilic carrier) and lactose (adsorbent). Response surface methodology (RSM) using the central composite design (CCD) was used to optimize independent variables like carrier concentrations and adsorbent concentrations, and their interactions with the dependent variables (responses), including solubility, angle of repose, Carr's index, and cumulative % drug release, were investigated. The optimized formulation was selected based on the numerical optimization method and further investigated for FTIR spectroscopy, differential scanning calorimetry, and X-ray diffractometry. Then, the optimized formulation was compressed into tablets and evaluated for both in vitro dissolution and in vivo pharmacokinetics parameters. In vitro dissolution studies revealed that the prepared fast-dissolving tablets released the drug entirely within 15 min (Q15 of F4 tablets: 99.34 ± 1.24%), whereas conventional tablets took around 60 min for complete dissolution. Pharmacokinetic studies in rats revealed that fast-dissolving tablets showed 1.38-fold higher peak-plasma concentration (Cmax) and 1.39-fold higher bioavailability than conventional tablets. Overall, this study revealed the successful fabrication of fast-dissolving tablets via melt-dispersion paired with the surface-adsorption method to enhance the flow properties and the dissolution rate.

Development of chitosan-graphene oxide blend nanoparticles for controlled flurbiprofen delivery

The use of natural polymeric nanoparticles (Nps) as drug carriers is a highly promising area of research in the field of drug delivery systems because of their high efficiency. In this study, flurbiprofen (FB) loaded chitosan-graphene oxide (CS-GO) blend Nps were synthesized as a controlled delivery system using the emulsion method. The crystalline, molecular, and morphological structures of the prepared CS-GO Nps were characterized using a variety of analytical methods, including Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-Ray diffractometry (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). It was found that the introduction of GO into the CS nanoparticle formulation increased its thermal stability. The range of the average particle size was between 362 ± 5.06 and 718 ± 2.21 nm, with negative zeta potential values between -7.67 ± 4.16 and - 27.93 ± 2.26 mV. The effects of the CS/GO ratio, the FB/polymer ratio, the amount of span 80, and the cross-linker concentration were assessed on FB release profiles. In vitro release studies displayed a two-stage release behaviour with a fast initial release of the FB, followed by sustained and extended release, and the incorporation of GO into the CS Nps made the FB release more sustained and controlled manner. Besides, the cytotoxicity test of the FB-loaded CS-GO Nps was studied through MTT assay, and it was found that they were biocompatible. Based on these findings, it can be inferred that the prepared CS-GO Nps might be a promising candidate drug carrier system for FB.

Modulation of γ-Secretase Activity by a Carborane-Based Flurbiprofen Analogue

All over the world, societies are facing rapidly aging populations combined with a growing number of patients suffering from Alzheimer's disease (AD). One focus in pharmaceutical research to address this issue is on the reduction of the longer amyloid-β (Aβ) fragments in the brain by modulation of γ-secretase, a membrane-bound protease. R-Flurbiprofen (tarenflurbil) was studied in this regard but failed to show significant improvement in AD patients in a phase 3 clinical trial. This was mainly attributed to its low ability to cross the blood-brain barrier (BBB). Here, we present the synthesis and in vitro evaluation of a racemic meta-carborane analogue of flurbiprofen. By introducing the carborane moiety, the hydrophobicity could be shifted into a more favourable range for the penetration of the blood-brain barrier, evident by a logD7.4 value of 2.0. Furthermore, our analogue retained γ-secretase modulator activity in comparison to racemic flurbiprofen in a cell-based assay. These findings demonstrate the potential of carboranes as phenyl mimetics also in AD research.

Efficient Palladium-Catalyzed Synthesis of 2-Aryl Propionic Acids

A flexible two-step, one-pot procedure was developed to synthesize 2-aryl propionic acids including the anti-inflammatory drugs naproxen and flurbiprofen. Optimal results were obtained in the presence of the novel ligand neoisopinocampheyldiphenylphosphine (NISPCPP) (9) which enabled the efficient sequential palladium-catalyzed Heck coupling of aryl bromides with ethylene and hydroxycarbonylation of the resulting styrenes to 2-aryl propionic acids. This cascade transformation leads with high regioselectivity to the desired products in good yields and avoids the need for additional purification steps.

Flurbiprofen-chalcone hybrid Mannich base derivatives as balanced multifunctional agents against Alzheimer's disease: Design, synthesis and biological evaluation

The complex pathogenesis of Alzheimer's disease (AD) calls for multitarget approach for disease management. Herein, a series of novel flurbiprofen-chalcone hybrid Mannich base derivatives were designed and synthesized. The biological screening results indicated that most of the derivatives exhibited potent multi-target effects involved in AD. In particular, compound 6c bearing a pyrrolidine group showed the highest activities against self- and Cu²⁺-induced Aβ_1-42 aggregation (70.65% and 54.89% at 25.0 µM, respectively), highly selective inhibition towards AChE and MAO-B (IC₅₀ = 7.15 μM and 0.43 μM respectively), good antioxidant ability and metal-chelating property. Moreover, 6c displayed excellent anti-neuroinflammatory activity and appropriate BBB permeability in vitro. These outstanding results qualified compound 6c as a promising multifunctional agent for further development of disease-modifying treatment of AD.

Regulating Preparation Of Functional Alginate-Chitosan Three-Dimensional Scaffold For Skin Tissue Engineering

AIM

In this study, we attempted to regulate the preparation of Alg-CS-Flu three-dimensional scaffolds via a facile freeze-drying method combined with amidation.

MATERIALS AND METHODS

Three-dimensional porous flurbiprofen-grafted alginate (Alg)-chitosan (CS) scaffolds were successfully prepared by a facile freeze-drying method combined with amidation for skin tissue engineering applications. Alg-CS composite was first used to load flurbiprofen (Flu), which is a kind of anti-inflammatory non-steroidal molecule. The Flu-loaded Alg/CS composite solution, through freeze-drying and 1-ethyl-3(3-(dimethylamino)propyl) carbodiimide/N-hydroxysuccinimide crosslinking to form an Alg-CS-Flu scaffold, exhibited a uniform and porous morphology that was characterized using scanning electron microscopy. The Alg-CS-Flu as-prepared scaffold was also characterized using Fourier-transform infrared spectroscopy, water contact angle, thermal properties, and stress-strain testing.

RESULTS

The results reveal that Flu was successfully grafted onto the surfaces of the Alg-CS-Flu scaffold, which showed good hydrophilicity and appropriate mechanical properties. Furthermore, cell viability, cell morphology from cells cultured in vitro, and hematoxylin-eosin staining after the graft was subcutaneously embedded in mice for 7 d demonstrated that the Alg-CS-Flu scaffold had no unfavorable effects on the adhesion and proliferation of fibroblasts, as well as a good anti-inflammatory property.

CONCLUSION

The developed Alg-CS-Flu scaffold is proposed as a promising material or skin tissue engineering application.

Clove oil based co-surfactant free microemulsion of flurbiprofen: Improved solubility with ameliorated drug-induced gastritis

Flurbiprofen, an NSAID, is a water insoluble drug that is also notorious for gastric irritation and inflammation. This study was aimed at using a natural gastrprotective oil as the internal phase to develop flurbiprofen micro emulsion (ME) to improve it solubility and ameliorate its gastric side effects. Upon screening of ME components for drug solubility, clove oil, tween 80 and transcutol were identified as the oil, surfactant and co surfactant, respectively, with higher flurbiprofen solubility. Pseudo-ternary phase diagrams revealed that the ME made with surfactant only and without co-surfactant displayed the similar ME region as made with the mixture of surfactant and co-surfactant. Furthermore, drug loaded oil was also used to draw pseudo-ternary phase diagram and a very little decrease in the ME region was observed. Therefore, co-surfactant free flurbiprofen loaded ME was developed to avoid side effects associated with the use of excessive surfactant quantities. ME were found to possess size in the range of 11-41 nm with PDI <0.5 and a slightly negative charge. Conductivity, pH and refractive indices of the selected MEs were well in the range. Drug release studies indicated maximum drug release from MEs within 5 min. Analysis of the gastric mucosa of rats after oral administration of drug solution and drug loaded ME confirmed that clove oil based ME provided significant protection against the NSAIDs induced gastric damage.

Development and optimization of flurbiprofen loaded microsponges; an in-vitro evaluation

Current study was designed with the aim to employ quasi emulsification, and double emulsification techniques for the development of Flurbiprofen (FLB) loaded micro sponges, followed by their physicochemical evaluation. FTIR interpretations exhibited compatibility of ingredients, while crystallographic analysis revealed crystalline nature of pure drug, which was masked upon incorporation into microsponges. Optical microscope and SEM have exposed spherical and spongy surfaces of prepared micro sponges. Micromeritics suggested that the flow properties are excellent and microsponges have remarkable drug entrapment efficiency (98.55±0.08%). In-vitro dissolution studies demonstrated good control over release of FLB until 8th h from the prepared microsponges. However, a difference in cumulated amount of released drug was noticed i.e. EC based formulation has released about 99.3±0.10%, while XG facilitated EC based formulations offered 92.7±2.1% release of the drug. Zeta potential indicated access of negative charge while zeta sizer has described the range of the particle size between 2.6 to 3.5μm. Conclusively the results have advocated the suitability of selected ingredients for incorporation of FLB into microsponges for its sustained delivery.

Simultaneous enantiomeric analysis of non-steroidal anti-inflammatory drugs in environment by chiral LC-MS/MS: A pilot study in Beijing, China

A simple, sensitive and quick method for direct simultaneous chiral analysis of frequently used non-steroidal anti-inflammatory drugs (NSAIDs) (ibuprofen, naproxen and flurbiprofen) in river water by HPLC-MS/MS was established and validated. Chromatographic parameters including the mobile phase composition, pH values, temperature and flow rates were optimized to obtain both satisfactory sensitivity and enantiomeric resolution (Rs≥ 1.0), which suggested the composition and pH values of mobile phase played crucial influence on enantioseparations. The method demonstrated its superiority compared with previous studies regarding to the low MQLs (1.1-37.1 ng/L) and short runtime (< 20 min), enabling quantitative enantiomeric determination of trace level of emerging contaminants in water. The environmental monitoring of receiving water (34 sites along rivers) in Beijing revealed ibuprofen was the most abundant, with mean concentration of 114.9 ng/L and detection frequency of 91%, naproxen was also detectable at all sites from < MQL-43.2 ng/L, both presenting an excess of the S-(+)-enantiomer. Therefore to better understand the ecological risk posed from the trace organic contaminants on the aquatic organisms, chiral pollutants need analyzed at the enantiomeric levels. This is the first to profile the enantiospecific occurrence of NSAIDs in surface water in Beijing, China. It could provide useful information on environmental behaviors of chiral pollutants and facilitate more accurate environmental risk assessment.

Dendrimeric Poly(Epsilon-Lysine) Delivery Systems for the Enhanced Permeability of Flurbiprofen across the Blood-Brain Barrier in Alzheimer's Disease

Alzheimer's disease (AD) is a progressive brain disorder and age-related disease characterised by abnormal accumulation of β-amyloid (Aβ). The development of drugs to combat AD is hampered by the lack of therapeutically-active molecules able to cross the blood-brain barrier (BBB). It is agreed that specifically-designed carriers, such as dendrimers, could support the drug penetration across the BBB. The aim of this study was to design biocompatible and biodegradable dendrimeric delivery systems able to carry Flurbiprofen (FP), as drug for AD treatment, across the BBB and liberate it at the target tissue. These dendrons were synthesised using solid-phase peptide synthesis method and characterised by mass spectrometry and fourier-transform infrared spectroscopy (FTIR). The results revealed successful synthesis of dendrons having FP been integrated during the synthesis at their branching ends. Cytotoxicity assays demonstrated the biocompatibility of the delivery systems, whereas HPLC analysis showed high percentages of permeability across an in vitro BBB model for FP-integrated dendrons. Results also revealed the efficiency of drug conjugates on the γ-secretase enzyme in target cells with evidence of eventual drug release by hydrolysis of the carrier. This study demonstrates that the coupling of FP to dendrimeric delivery systems can successfully be achieved during the synthesis of the poly(epsilon-lysine) macromolecules to improve the transport of the active drug across the BBB.

The nature of hydrogen-bonding interactions in nonsteroidal anti-inflammatory drugs revealed by polarized IR spectroscopy

The influence of hydrogen-bonding interactions in the solid phase on the IR spectroscopic pattern of the ν_OH band of nonsteroidal anti-inflammatory drugs (NSAIDs) was studied experimentally by IR spectroscopy with the use of polarized light at two temperatures (293K and 77K) and in isotopic dilution. The neat and deuterated crystals of (S)-naproxen ((S)-NPX), (R)-flurbiprofen ((R)-FBP), (RS)-flurbiprofen ((RS)-FBP) and (RS)-ketoprofen ((RS)-KTP) were obtained by melt crystallization between the two squeezed CaF₂ plates. The vibrational spectra of selected α-aryl propionic acid derivatives (2APAs) reflected the characteristics of their hydrogen-bond networks, i.e., 2APAs were characterized by the chain ((S)-NPX, (R)-FBP) and by dimeric ((RS)-FBP, (RS)-KTP) arrangement of hydrogen bonds in the crystal lattice. Spectroscopic results showed that the interchain (through-space) exciton coupling, between two laterally-spaced hydrogen bonds, dominates in the crystals of four NSAIDs. The same exciton coupled hydrogen bonds were also responsible for the H/D isotopic recognition mechanism in the crystalline spectra of deuterated 2APAs. The presented spectral results may help to predict the hydrogen bond motifs in the crystalline NSAIDs, which structures are not yet known, based on their IR spectra of hydrogen bond in the crystals.

Metal organic frameworks as a drug delivery system for flurbiprofen

BACKGROUND

Metal organic frameworks (MOFs) have attracted more attention in the last decade because of a suitable pore size, large surface area, and high pore volume. Developing biocompatible MOFs such as the MIL family as a drug delivery system is possible.

PURPOSE

Flurbiprofen (FBP), a nonsteroidal anti-inflammatory agent, is practically insoluble in aqueous solution, and, therefore, needs suitable drug delivery systems. Different biocompatible MOFs such as Ca-MOF and Fe-MILs (53, 100, and 101) were synthesized and employed for FBP delivery.

PATIENTS AND METHODS

A sample of 50 mg of each MOF was mixed and stirred for 24 h with 10 mL of 5 mg FBP in acetonitrile (40%) in a sealed container. The supernatant of the mixture after centrifuging was analyzed by high-performance liquid chromatography to determine the loaded quantity of FBP on the MOF. The overnight-dried solid material after centrifuging the mixture was analyzed for loading percent using X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, nuclear magnetic resonance, and FBP release profile.

RESULTS

The loading values of FBP were achieved at 10.0%±1%, 20%±0.8%, 37%±2.3%, and 46%±3.1% on Ca-MOF, Fe-MIL-53, Fe-MIL-101, and Fe-MIL-100, respectively. The FBP release profiles were investigated in a phosphate buffer solution at pH 7.4. The total release of the FBP after 2 days was obtained at 72.9, 75.2, 78.3, and 90.3% for Ca-MOF, Fe-MIL-100, Fe-MIL-53, and Fe-MIL-101, respectively.

CONCLUSION

The MOFs are shown to be a promising drug delivery option for FBP with a significant loading percent and relatively prolonged drug release.

Sustained release of intravitreal flurbiprofen from a novel drug-in-liposome-in-hydrogel formulation

A novel Flurbiprofen (FLB)-in-liposome-in-hydrogel formulation was developed, as a method to sustain the release and increase the ocular bioavailability of FLB following intravitreal injection. For this, FLB loading into liposomes was optimized and liposomes were entrapped in thermosensitive hydrogels consisted of Pluronic F-127 (P). FLB solution, liposomes, and FLB dissolved in hydrogel were also used as control formulations. Actively loaded liposomes were found to be optimal for high FLB loading and small size, while in vitro studies revealed that P concentration of 18% (w/v) was best to retain the integrity of the hydrogel-dispersed liposome, compared to a 20% concentration. The in vitro release of FLB was significantly sustained when FLB-liposomes were dispersed in the hydrogel compared to hydrogel dissolved FLB, as well as the other control formulations. In vivo studies were carried out in pigmented rabbits which were injected through a 27G needle with 1mg/mL FLB in the different formulation-types. Ophthalmic examinations after intravitreal injection of all FLB formulations, revealed no evidence of inflammation, hemorrhage, uveitis or endophthalmitis. Pharmacokinetic analysis results confirm that the hybrid drug delivery system increases the bioavailability (by 1.9 times compared to solution), and extends the presence of the drug in the vitreous cavity, while liposome and hydrogel formulations demonstrate intermediate performance. Furthermore the hybrid system increases MRT of FLB in aqueous humor and retina/choroid tissues, compared to all the control formulations. Currently the potential therapeutic advances of FLB sustained release formulations for IVT administration are being evaluated.

C(sp2)-H Borylation of Fluorinated Arenes Using an Air-Stable Cobalt Precatalyst: Electronically Enhanced Site Selectivity Enables Synthetic Opportunities

Cobalt catalysts with electronically enhanced site selectivity have been developed, as evidenced by the high ortho-to-fluorine selectivity observed in the C(sp2)-H borylation of fluorinated arenes. Both the air-sensitive cobalt(III) dihydride boryl 4-Me-(iPrPNP)Co(H)2BPin (1) and the air-stable cobalt(II) bis(pivalate) 4-Me-(iPrPNP)Co(O2CtBu)2 (2) compounds were effective and exhibited broad functional group tolerance across a wide range of fluoroarenes containing electronically diverse functional groups, regardless of the substitution pattern on the arene. The electronically enhanced ortho-to-fluorine selectivity observed with the cobalt catalysts was maintained in the presence of a benzylic dimethylamine and hydrosilanes, overriding the established directing-group effects observed with precious-metal catalysts. The synthetically useful selectivity observed with cobalt was applied to an efficient synthesis of the anti-inflammatory drug flurbiprofen.

R-Flurbiprofen Traps Prostaglandins within Cells by Inhibition of Multidrug Resistance-Associated Protein-4

R-flurbiprofen is the non-COX-inhibiting enantiomer of flurbiprofen and is not converted to S-flurbiprofen in human cells. Nevertheless, it reduces extracellular prostaglandin E₂ (PGE₂) in cancer or immune cell cultures and human extracellular fluid. Here, we show that R-flurbiprofen acts through a dual mechanism: (i) it inhibits the translocation of cPLA_2α to the plasma membrane and thereby curtails the availability of arachidonic acid and (ii) R-flurbiprofen traps PGE₂ inside of the cells by inhibiting multidrug resistance–associated protein 4 (MRP4, ABCC4), which acts as an outward transporter for prostaglandins. Consequently, the effects of R-flurbiprofen were mimicked by RNAi-mediated knockdown of MRP4. Our data show a novel mechanism by which R-flurbiprofen reduces extracellular PGs at physiological concentrations, particularly in cancers with high levels of MRP4, but the mechanism may also contribute to its anti-inflammatory and immune-modulating properties and suggests that it reduces PGs in a site- and context-dependent manner.

Flurbiprofen-antioxidant mutual prodrugs as safer nonsteroidal anti-inflammatory drugs: synthesis, pharmacological investigation, and computational molecular modeling

Flurbiprofen-antioxidant mutual prodrugs were synthesized to reduce the gastrointestinal (GI) effects associated with flurbiprofen. For reducing the GI toxicity, the free carboxylic group (-COOH) was temporarily masked by esterification with phenolic -OH of natural antioxidants vanillin, thymol, umbelliferone, and sesamol. The in vitro hydrolysis of synthesized prodrugs showed that they were stable in buffer solution at pH 1.2, indicating their stability in the stomach. The synthesized prodrugs undergo significant hydrolysis in 80% human plasma and thus release free flurbiprofen. The minimum reversion was observed at pH 1.2, suggesting that prodrugs are less irritating to the stomach than flurbiprofen. The anti-inflammatory, analgesic, antipyretic, and ulcerogenic activities of prodrugs were evaluated. All the synthesized prodrugs significantly (P<0.001) reduced the inflammation against carrageenan and egg albumin-induced paw edema at 4 hours of study. The reduction in the size of the inflamed paw showed that most of the compounds inhibited the later phase of inflammation. The prodrug 2-oxo-2H-chromen-7-yl-2-(2-fluorobiphenyl-4-yl)propanoate (4b) showed significant reduction in paw licking with percentage inhibition of 58%. It also exhibited higher analgesic activity, reducing the number of writhes with a percentage of 75%, whereas flurbiprofen showed 69% inhibition. Antipyretic activity was investigated using brewer's yeast-induced pyrexia model, and significant (P<0.001) reduction in rectal temperature was shown by all prodrugs at all times of assessment. The results of ulcerogenic activity showed that all prodrugs produced less GI irritation than flurbiprofen. Molecular docking and simulation studies were carried out with cyclooxygenase (COX-1 and COX-2) proteins, and it was observed that our prodrugs have more potential to selectively bind to COX-2 than to COX-1. It is concluded that the synthesized prodrugs have promising pharmacological activities with reduced GI adverse effects than the parent drug.

Development of an ANN optimized mucoadhesive buccal tablet containing flurbiprofen and lidocaine for dental pain

A novel mucoadhesive buccal tablet containing flurbiprofen (FLB) and lidocaine HCl (LID) was prepared to relieve dental pain. Tablet formulations (F1-F9) were prepared using variable quantities of mucoadhesive agents, hydroxypropyl methyl cellulose (HPMC) and sodium alginate (SA). The formulations were evaluated for their physicochemical properties, mucoadhesive strength and mucoadhesion time, swellability index and in vitro release of active agents. Release of both drugs depended on the relative ratio of HPMC:SA. However, mucoadhesive strength and mucoadhesion time were better in formulations, containing higher proportions of HPMC compared to SA. An artificial neural network (ANN) approach was applied to optimise formulations based on known effective parameters (i.e., mucoadhesive strength, mucoadhesion time and drug release), which proved valuable. This study indicates that an effective buccal tablet formulation of flurbiprofen and lidocaine can be prepared via an optimized ANN approach.

Nanoscale electron transport measurements of immobilized cytochrome P450 proteins

Gold nanopillars, functionalized with an organic self-assembled monolayer, can be used to measure the electrical conductance properties of immobilized proteins without aggregation. Measurements of the conductance of nanopillars with cytochrome P450 2C9 (CYP2C9) proteins using conducting probe atomic force microscopy demonstrate that a correlation exists between the energy barrier height between hopping sites and CYP2C9 metabolic activity. Measurements performed as a function of tip force indicate that, when subjected to a large force, the protein is more stable in the presence of a substrate. This agrees with the hypothesis that substrate entry into the active site helps to stabilize the enzyme. The relative distance between hopping sites also increases with increasing force, possibly because protein functional groups responsible for electron transport (ETp) depend on the structure of the protein. The inhibitor sulfaphenazole, in addition to the previously studied aniline, increased the barrier height for electron transfer and thereby makes CYP2C9 reduction more difficult and inhibits metabolism. This suggests that P450 Type II binders may decrease the ease of ETp processes in the enzyme, in addition to occupying the active site.

CYP2C9 genotype vs. metabolic phenotype for individual drug dosing--a correlation analysis using flurbiprofen as probe drug

Currently, genotyping of patients for polymorphic enzymes responsible for metabolic elimination is considered a possibility to adjust drug dose levels. For a patient to profit from this procedure, the interindividual differences in drug metabolism within one genotype should be smaller than those between different genotypes. We studied a large cohort of healthy young adults (283 subjects), correlating their CYP2C9 genotype to a simple phenotyping metric, using flurbiprofen as probe drug. Genotyping was conducted for CYP2C9*1, *2, *3. The urinary metabolic ratio MR (concentration of CYP2C9-dependent metabolite divided by concentration of flurbiprofen) determined two hours after flurbiprofen (8.75 mg) administration served as phenotyping metric. Linear statistical models correlating genotype and phenotype provided highly significant allele-specific MR estimates of 0.596 for the wild type allele CYP2C9*1, 0.405 for CYP2C9*2 (68 % of wild type), and 0.113 for CYP2C9*3 (19 % of wild type). If these estimates were used for flurbiprofen dose adjustment, taking 100 % for genotype *1/*1, an average reduction to 84 %, 60 %, 68 %, 43 %, and 19 % would result for genotype *1/*2, *1/*3, *2/*2, *2/*3, and *3/*3, respectively. Due to the large individual variation within genotypes with coefficients of variation ≥ 20 % and supposing the normal distribution, one in three individuals would be out of the average optimum dose by more than 20 %, one in 20 would be 40 % off. Whether this problem also applies to other CYPs and other drugs has to be investigated case by case. Our data for the given example, however, puts the benefit of individual drug dosing to question, if it is exclusively based on genotype.

High enantioselective Novozym 435-catalyzed esterification of (R,S)-flurbiprofen monitored with a chiral stationary phase

Lipases form Candida rugosa and Candida antarctica were tested for their application in the enzymatic kinetic resolution of (R,S)-flurbiprofen by enantioselective esterification. Successful chromatographic separation with well-resolved peaks of (R)- and (S)-flurbiprofen and their esters was achieved in one run on chiral stationary phases by high-performance liquid chromatography (HPLC). In this study screening of enzymes was performed, and Novozym 435 was selected as an optimal catalyst for obtaining products with high enantiopurity. Additionally, the influence of organic solvents (dichloromethane, dichloroethane, dichloropropane, and methyl tert-butyl ether), primary alcohols (methanol, ethanol, n-propanol, and n-butanol), reaction time, and temperature on the enantiomeric ratio and conversion was tested. The high values of enantiomeric ratio (E in the range of 51.3-90.5) of the esterification of (R,S)-flurbiprofen were obtained for all tested alcohols using Novozym 435, which have a great significance in the field of biotechnological synthesis of drugs. The optimal temperature range for the performed reactions was from 37 to 45 °C. As a result of the optimization, (R)-flurbiprofen methyl ester was obtained with a high optical purity, eep = 96.3 %, after 96 h of incubation. The enantiomeric ratio of the reaction was E = 90.5 and conversion was C = 35.7 %.

Formulation design and characterization of an elementary osmotic pump tablet of flurbiprofen

Elementary osmotic pumps are well known for delivering moderately soluble drugs at a zero-order rate. The objective of the present study was to develop elementary osmotic pump tablets containing Flurbiprofen using an inclusion complex. Formation of complex was confirmed by Differential Scanning Calorimetry and Fourier Transform Infrared Spectroscopy. A 3(2) factorial design was applied systematically; the amount of osmotic agent (X1) and size of delivery orifice (X2) were selected as independent variables. Batches were prepared by the direct compression method and evaluated for percent cumulative drug release (%CDR) at 9 h as dependent variables. The amount of osmotic agent and size of the delivery orifice had a significant effect on %CDR. The results of multiple linear regression analysis revealed that elementary osmotic pump tablets should be prepared using an optimum concentration of osmotic agent and size of delivery orifice to achieve a zero-order drug release. Contour plots as well as response surface plots were constructed to show the effects of X1 and X2 on %CDR. A model was validated for accurate prediction of %CDR by performing checkpoint analysis. The computer optimization process, contour plots, and response surface plots were predicted at the concentration of independent variables X1 and X2 (78.38 mg and 0.99 mm, respectively), for maximized response. The drug release from the developed formulation was found to be independent of pH and agitational intensity. The above optimized batch was also evaluated by different pharmacokinetic models like zero-order, first-order, Higuchi, Korsmeyer Peppas, and Hixson Crowell models. Stability study of the optimized batch was conducted at accelerated conditions for 6 months, and was found stable. This study strongly indicates application of osmotic tablets of Flurbiprofen for the treatment of rheumatoid arthritis, as well as osteoarthritis.

LAY ABSTRACT

The aim of this study was to develop an elementary osmotic pump tablet of Flurbiprofen and to deliver the drug at a zero-order rate. Elementary osmotic pumps are well known for delivering moderately soluble drugs at a zero-order rate. Elementary osmotic pump tablets containing an inclusion complex of Flurbiprofen was prepared by the direct compression method. The amount of osmotic agent and size of delivery orifice were selected as independent variables. Percent cumulative drug release at 9 h was evaluated for all batches, and it was found that amount of osmotic agent and size of delivery orifice had a significant effect on percent cumulative drug release. The drug release from the developed formulation was found to be independent of pH and agitational intensity. It was also observed that the optimized formulation followed zero-order kinetics and was stable for 6 months at accelerated conditions.

Pharmacokinetics of colon-specific pH and time-dependent flurbiprofen tablets

Present research deals with the development of compression-coated flurbiprofen colon-targeted tablets to retard the drug release in the upper gastro intestinal system, but progressively release the drug in the colon. Flurbiprofen core tablets were prepared by direct compression method and were compression coated using sodium alginate and Eudragit S100. The formulation is optimized based on the in vitro drug release study and further evaluated by X-ray imaging and pharmacokinetic studies in healthy humans for colonic delivery. The optimized formulation showed negligible drug release (4.33 ± 0.06 %) in the initial lag period followed by progressive release (100.78 ± 0.64 %) for 24 h. The X-ray imaging in human volunteers showed that the tablets reached the colon without disintegrating in the upper gastrointestinal tract. The C max of colon-targeted tablets was 12,374.67 ng/ml at T max 10 h, where as in case of immediate release tablets the C max was 15,677.52 ng/ml at T max 3 h, that signifies the ability of compression-coated tablets to target the colon. Development of compression-coated tablets using combination of time-dependent and pH-sensitive approaches was suitable to target the flurbiprofen to colon.

Synthesis of some new flurbiprofen analogues as anti-inflammatory agents

A series of new α-aryl propionic acid derivatives had been synthesized through different synthetic routes from the readily available 2-fluoronitrobenzene as key starter. The synthesized compounds were screened for their antiinflammatory activity using rat paw edema method. Azoles (6c, 6h and 6i) have showed considerable good antiinflammatory activity. The present series with some modification may serve as important core for the development of new anti-inflammatory agents.

Enhanced bioavailability of orally administered flurbiprofen by combined use of hydroxypropyl-cyclodextrin and poly(alkyl-cyanoacrylate) nanoparticles

Flurbiprofen was formulated into nanoparticle suspension to improve its oral bioavailability. Hydroxypropyl-β-cyclodextrin inclusion-flurbiprofen complex (HP-β-CD-FP) was prepared, then incorporating this complex into poly(alkyl-cyanoacrylate) (PACA) nanoparticles. HP-β-CD-FP-PACA nanoparticle was prepared by the emulsion solvent polymerization method. The zeta potential was -26.8 mV, the mean volume particle diameter was 134 nm, drug encapsulation efficiency was 53.3 ± 3.6 % and concentration was 1.5 mg/mL. The bioavailability of flurbiprofen from optimized nanoparticles was assessed in male Wistar rats at a dose of 15 mg/kg. As compared to the flurbiprofen suspension, 211.6 % relative bioavailability was observed for flurbiprofen nanoparticles. The reduced particle size and increased surface area may contribute to improve oral bioavailability of flurbiprofen.

Design, synthesis and evaluation of tacrine-flurbiprofen-nitrate trihybrids as novel anti-Alzheimer's disease agents

To search for multifunctional anti-Alzheimer's disease (AD) agents with good safety, the previously synthesized tacrine-flurbiprofen hybrids 1a and 1b were modified into tacrine-flurbiprofen-nitrate trihybrids 3a-h. These compounds displayed comparable or higher cholinesterase inhibitory activity relative to the bivalent hybrids. Compound 3a was the most potent, which released moderate NO, exerted blood vessel relaxative activity, and showed significant Aβ inhibitory effects whereas tacrine and flurbiprofen did not exhibit any Aβ inhibitory activity at the same dose. In addition, 3a was active in improving memory impairment in vivo. More importantly, the hepatotoxicity study showed that 3a was much safer than tacrine, suggesting it might be a promising anti-AD agent for further investigation.

The formulation of flurbiprofen loaded microspheres using hydroxypropylmethycellulose and ethylcellulose

OBJECTIVES

The aim of the present work was to formulate flurbiprofen (FLB) loaded microspheres of hydroxypropylmethycellulose and ethylcellulose polymers to study the effect of different proportions of the polymer mixture on the release behavior of the drug.

MATERIAL AND METHODS

A series of microspheres were prepared using tween-80 as a surfactant. The prepared microspheres were evaluated for entrapment efficiency (%) and percentage recovery. Drug release was performed in USP phosphate buffers of pH 1.2 and 6.8. Drug release data were plotted in various kinetic models, including zero-order, first-order, Higuchi and Korsmeyer-Peppas models to investigate the optimum composition suitable for sustained drug delivery.

RESULTS

A significant difference in drug release kinetics was observed by varying the composition of hydroxypropylmethycellulose/ethylcellulose. As the ratio of EC/HPMC was increased, the release rate of flurbiprofen decreased.

CONCLUSIONS

This study demonstrated the potential of polymer combinations in the formulation of microspheres for water-insoluble drugs utilizing HPMC and EC as release retardant materials, using a simple solvent evaporation microencapsulation technique. It was observed that various physico-chemical properties of the microspheres varied according to the change in polymer concentrations used in the formulations.

Enantioseparations in nonaqueous capillary electrophoresis using charged cyclodextrins

The enantioseparation of acidic and basic compounds can be successfully achieved in nonaqueous capillary electrophoresis using single-isomer charged β-cyclodextrin (β-CD) derivatives of opposite charge to that of the analytes. This chapter describes how to separate the enantiomers of three basic substances selected as model compounds, i.e., alprenolol, bupranolol, and terbutaline, using the negatively charged heptakis(2,3-di-O-acetyl-6-O-sulfo)-β-CD. The enantiomers of three acidic drugs (tiaprofenic acid, suprofen, and flurbiprofen) are resolved using a monosubstituted amino β-CD derivative, namely, 6-monodeoxy-6-mono(3-hydroxy)propylamino-β-CD.

Study of the solvent effects on the molecular structure and CO stretching vibrations of flurbiprofen

The effects of 15 solvents on the C=O stretching vibrational frequency of flurbiprofen (FBF) were determined to investigate solvent-solute interactions. Solvent effects on the geometry and C=O stretching vibrational frequency, ν(C=O), of FBF were studied theoretically at the DFT/B3LYP and HF level in combination with the polarizable continuum model and experimentally using attenuated total reflection infrared spectroscopy (ATR-IR). The calculated C=O stretching frequencies in the liquid phase are in agreement with experimental values. Moreover, the wavenumbers of ν(C=O) of FBF in different solvents have been obtained and correlated with the Kirkwood-Bauer-Magat equation (KBM), the solvent acceptor numbers (ANs), and the linear solvation energy relationships (LSERs). The solvent-induced stretching vibrational frequency shifts displayed a better correlation with the LSERs than with the ANs and KBM.

Crystal structures of three classes of non-steroidal anti-inflammatory drugs in complex with aldo-keto reductase 1C3

Aldo-keto reductase 1C3 (AKR1C3) catalyses the NADPH dependent reduction of carbonyl groups in a number of important steroid and prostanoid molecules. The enzyme is also over-expressed in prostate and breast cancer and its expression is correlated with the aggressiveness of the disease. The steroid products of AKR1C3 catalysis are important in proliferative signalling of hormone-responsive cells, while the prostanoid products promote prostaglandin-dependent proliferative pathways. In these ways, AKR1C3 contributes to tumour development and maintenance, and suggest that inhibition of AKR1C3 activity is an attractive target for the development of new anti-cancer therapies. Non-steroidal anti-inflammatory drugs (NSAIDs) are one well-known class of compounds that inhibits AKR1C3, yet crystal structures have only been determined for this enzyme with flufenamic acid, indomethacin, and closely related analogues bound. While the flufenamic acid and indomethacin structures have been used to design novel inhibitors, they provide only limited coverage of the NSAIDs that inhibit AKR1C3 and that may be used for the development of new AKR1C3 targeted drugs. To understand how other NSAIDs bind to AKR1C3, we have determined ten crystal structures of AKR1C3 complexes that cover three different classes of NSAID, N-phenylanthranilic acids (meclofenamic acid, mefenamic acid), arylpropionic acids (flurbiprofen, ibuprofen, naproxen), and indomethacin analogues (indomethacin, sulindac, zomepirac). The N-phenylanthranilic and arylpropionic acids bind to common sites including the enzyme catalytic centre and a constitutive active site pocket, with the arylpropionic acids probing the constitutive pocket more effectively. By contrast, indomethacin and the indomethacin analogues sulindac and zomepirac, display three distinctly different binding modes that explain their relative inhibition of the AKR1C family members. This new data from ten crystal structures greatly broadens the base of structures available for future structure-guided drug discovery efforts.

Nano-pulverization of poorly water soluble compounds with low melting points by a rotation/revolution pulverizer

We report a method for pulverizing poorly water soluble compounds with low melting points to nanoparticles without producing an amorphous phase using a rotation/revolution pulverizer. Fenofibrate, flurbiprofen, and probucol were used as crystalline model compounds. They were suspended in a methylcellulose aqueous solution and pulverized with zirconia balls by the rotation/revolution pulverizer. Beeswax, an amorphous compound, was also examined to investigate whether nano-pulverization of a compound with a low melting point was possible. Beeswax was suspended in ethyl alcohol cooled with liquid nitrogen and pulverized with zirconia balls by the rotation/revolution pulverizer. By optimizing the pulverization parameters, nanoparticles (D50 < 0.15 microm) of the crystalline compounds were obtained with narrow particle size distributions at a rotation/revolution speed of 1000 rpm and a rotation/revolution ratio of 1.0 when the vessel was 0 degrees C. Amorphous fenofibrate and flurbiprofen were not detected by differential scanning calorimetry or powder X-ray diffraction, whereas small amounts of amorphous probucol were detected. Beeswax was pulverized to nanoparticles (D50 = 0.14 microm) with ethyl alcohol cooled with liquid nitrogen. Fine nanoparticles of these poorly water soluble compounds with low melting points were obtained by controlling the rotation/revolution speed and reducing the vessel temperature.

Modulation of drug release from nanocarriers loaded with a poorly water soluble drug (flurbiprofen) comprising natural waxes

In this study, flurbiprofen (FLB) Solid Lipid Nanoparticles (SLN) composed from a mixture of beeswax and carnauba wax, Tween 80 and egg lecithin as emulsifiers have been prepared. FLB was incorporated as model lipophilic drug to assess the influence of matrix composition in the drug release profile. SLN were produced by microemulsion technique. In vitro studies were performed in Phosphate Buffered Saline (PBS). The FLB loaded SLN showed a mean particle size of 75 +/- 4 nm, a polydispersity index approximately 0.2 +/- 0.02 and an entrapment efficiency (EE) of more than 95%. Suspensions were stable, with zeta potential values in the range of -15 to -17 mV. DSC thermograms and UV analysis indicated the stability of nanoparticles with negligible drug leakage. Nanoparticles with higher beeswax content in their core exhibited faster drug release than those containing more carnauba wax.

Beyond benzyl grignards: facile generation of benzyl carbanions from styrenes

Benzylic functionalization is a convenient approach towards the conversion of readily available aromatic hydrocarbon feedstocks into more useful molecules. However, the formation of carbanionic benzyl species from benzyl halides or similar precursors is far from trivial. An alternative approach is the direct reaction of a styrene with a suitable coupling partner, but these reactions often involve the use of precious-metal transition-metal catalysts. Herein, we report the facile and convenient generation of reactive benzyl anionic species from styrenes. A Cu(I)-catalyzed Markovnikov hydroboration of the styrenic double bond by using a bulky pinacol borane source is followed by treatment with KOtBu to facilitate a sterically induced cleavage of the C-B bond to produce a benzylic carbanion. Quenching this intermediate with a variety of electrophiles, including CO(2), CS(2), isocyanates, and isothiocyanates, promotes C-C bond formation at the benzylic carbon atom. The utility of this methodology was demonstrated in a three-step, two-pot synthesis of the nonsteroidal anti-inflammatory drug (±)-flurbiprofen.

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.

Effect of olive oil on transdermal penetration of flurbiprofen from topical gel as enhancer

The present study was conducted to formulate and evaluate flurbiprofen transdermal gel. A standard calibration curve was constructed to obtain a regression line equation to be used for finding out the concentration of drug in samples. Olive oil was used as penetration enhancer and was added in different concentrations to some selected formulations to see its enhancement effect on in vitro drug release profiles. The prepared gels were evaluated for several physico-chemical parameters to justify their suitability for topical use. The in vitro drug release studies were carried out by using Franz cell diffusion apparatus across both synthetic membrane and excised albino rabbit skin. In order to investigate the drug release mechanism a kinetic approach was made by employing Korsmeyer kinetic model to the in vitro drug release profiles of flurbiprofen. The flurbiprofen topical gels were successfully prepared and could be beneficial for topical use.

Development and evaluation of mucoadhesive buccal patches of flurbiprofen

In the present study, an attempt was made to formulate mucoadhesive buccal patches of flurbiprofen (FBN) in order to enhance solubility. Solubity enhancement was attempted by making solid dispersion of drug with beta-CD (cyclodextrin). Initially preformulation were carried out using reported methods. Buccal patches were prepared by solvent casting technique using polymers like polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (SCMC), and hydroxypropyl methylcellulose (HPMC). The prepared patches were evaluated for their weight variation, thickness, folding endurance, surface pH, swelling index, in vitro residence time, in vitro permeation studies, drug content uniformity and bioadhesion test.

Flurbiprofen encapsulation using pluronic triblock copolymers

Pulsed-field gradient stimulated-echo nuclear magnetic resonance (NMR) and surface tension measurements have been used to study the effect of drug addition on the micellization behavior of pluronic triblock copolymers (P103, P123, and L43). The addition of 0.6 wt% flurbiprofen to Pluronic P123 and P103 solutions reduced their cmc and promoted micellization. Also, a substantial increase in the hydrodynamic radius of Pluronic P103 from 5 to 10 nm was observed, along with an increased fraction of polymer micellized, demonstrating that the polymers solubilize this nonsteroidal anti-inflammatory drug.

Observation of an unusual electronically distorted semiquinone radical of PCB metabolites in the active site of prostaglandin H synthase-2

The activation of the metabolites of airborne polychlorinated biphenyls (PCBs) into highly reactive radicals is of fundamental importance. We found that human recombinant prostaglandin H synthase-2 (hPGHS-2) biotransforms dihydroxy-PCBs, such as 4-chlorobiphenyl-2',5'-hydroquinone (4-CB-2',5'-H(2)Q), into semiquinone radicals via one-electron oxidation. Using electron paramagnetic resonance (EPR) spectroscopy, we observed the formation of the symmetric quartet spectrum (1:3:3:1 by area) of 4-chlorobiphenyl-2',5'-semiquinone radical (4-CB-2',5'-SQ()(-)) from 4-CB-2',5'-H(2)Q. This spectrum changed to an asymmetric spectrum with time: the change can be explained as the overlap of two different semiquinone radical species. Hindered rotation of the 4-CB-2',5'-SQ()(-) appears not to be a major factor for the change in lineshape because increasing the viscosity of the medium with glycerol produced no significant change in lineshape. Introduction of a fluorine, which increases the steric hindrance for rotation of the dihydroxy-PCB studied, also produced no significant changes. An in silico molecular docking model of 4-CB-2',5'-H(2)Q in the peroxidase site of hPGHS-2 together with ab initio quantum mechanical studies indicate that the close proximity of a negatively charged carboxylic acid in the peroxidase active site may be responsible for the observed perturbation in the spectrum. This study provides new insights into the formation of semiquinones from PCB metabolites and underscores the potential role of PGHS-2 in the metabolic activation of PCBs.

Enhancement of dissolution and bioavailability of flurbiprofen by low molecular weight chitosans

The dissolution behavior and absorption of flurbiprofen (FP) following oral administration from:three types of chitosans (LM chitosans), with different molecular weights and degree of acetylation, have been studied in comparison with those of the drug alone. The solubility of FP increased with concentrations of LM chitosan, especially in the case of C-III, with the highest degree of deacetylation degree among the three chitosans. This indicates that amino groups of LM chitosan play an important role in its interaction with FP. Moreover, spectroscopic studies, including NMR data, indicate that the binding involves interactions between the carboxyl group of FP and the amino group of the chitosans. The dissolution rates of FP for a C-III kneaded mixture were enhanced with increasing amounts of C-III. The oral absorption of FP from a C-III kneaded mixture was improved to a significant extent, compared to FP alone. These results suggest that FP from LM chitosan kneaded mixture increases the dissolution rate and improves the bioavailability of the drug by the formation of a water-soluble complex.

Influence of preparation methodology on solid-state properties of an acidic drug-cyclodextrin system

We have investigated the influence of processing variables on the solid-state of a model drug, flurbiprofen, in cyclodextrin-based systems and its effect on dissolution behaviour of the drug. The interaction between flurbiprofen and hydroxypropyl β-cyclodextrin (HP-β-CyD) was studied by NMR spectroscopy and phase solubility studies. Binary systems containing flurbiprofen and HP-β-CyD or povidone (polyvinylpyrrolidone) K30, prepared by various processes, were characterized by FTIR, DSC, XRD and dissolution studies. HP-β-CyD enhanced the solubility of flurbiprofen and increased dissolution rates from binary systems. It was found to be superior to povidone K30 in producing higher dissolution rates. The method of preparation of the binary systems and the agents used were found to have a major influence on the final solid-state of flurbiprofen. Solvents and processing conditions favouring greater interaction between flurbiprofen and the cyclodextrin during the preparation process resulted in greater extent of drug-cyclodextrin association and/or greater amorphization of the drug. Use of ammonia during the preparation of binary systems yielded solids from which very rapid drug dissolution was achieved, due to a higher extent of molecular dispersion of the drug. Processing variables therefore could significantly influence the solid-state of a drug in cyclodextrin-based formulations and thereby affect its dissolution behaviour. This could lead to significant effects on the in-vivo performance of the formulation.

Spectroscopic and DFT studies of flurbiprofen as dimer and its Cu(II) and Hg(II) complexes

The vibrational study in the solid state of flurbiprofen and its Cu(II) and Hg(II) complexes was performed by IR and Raman spectroscopy. The changes observed between the IR and Raman spectra of the ligand and of the complexes allowed us to establish the coordination mode of the metal in both complexes. The comparative vibrational analysis of the free ligand and its complexes gave evidence that flurbiprofen binds metal (II) through the carboxylate oxygen. The fully optimized equilibrium structure of flurbiprofen and its metal complexes was obtained by density functional B3LYP method by using LanL2DZ and 6-31 G(d,p) basis sets. The harmonic vibrational frequencies, infrared intensities and Raman scattering activities of flurbiprofen were calculated by density functional B3LYP methods by using 6-31G(d,p) basis set. The scaled theoretical wavenumbers showed very good agreement with the experimental values. The electronic properties of the free molecule and its complexes were also performed at B3LYP/6-31G(d,p) level of theory. Detailed interpretations of the infrared and Raman spectra of flurbiprofen are reported. The UV-vis spectra of flurbiprofen and its metal complexes were also investigated in organic solvents.

Preparation and Characterization of Poly(D,L-Lactic-Co-Glycolic Acid) Microspheres Containing Flurbiprofen Sodium

This study aimed to prepare biodegradable microspheres containing flurbiprofen sodium, a nonsteroidal anti-inflammatory drug (NSAID), as the drug delivery system to the periodontal pocket. Microspheres were prepared from biodegradable copolymers of poly (D,L-lactic-co-glycolic acid) (PLGA) using solvent evaporation method. The effects of the different copolymers and amounts of polyvinyl alcohol (PVA) as a dispersing agent on characteristics of the microspheres were evaluated. Although there was no correlation between microsphere size and amount of PVA, an optimum PVA concentration was essential to achieve narrower size distributions of microspheres. As the concentration of PVA increased, the drug loading of the microspheres increased. The effect of PVA on drug loading was found to be statistically significant for those microspheres prepared from PLGA 50:50 (p < 0.05). Regarding copolymer composition, PLGA 85:15 provided higher drug loading into the microspheres than PLGA 50:50 (p < 0.05). The recoveries of microspheres (60-80%) were affected neither by different PVA concentrations nor by copolymer compositions (p > 0.05). According to the first-order release rate constants of the microspheres, the microspheres of PLGA 50:50 released the drug at the highest rate consistently, with the highest hydrophilicity of this copolymer.

Formulation Studies and In Vivo Evaluation of a Flurbiprofen-Hydroxypropyl β-Cyclodextrin System

The purpose of this study was 1) to investigate in vivo advantages of a flurbiprofen (FPN)-hydroxypropyl beta-cyclodextrin (HPbetaCD) solid dispersion (SD) in rats, 2) to study factors affecting the drug release from SD formulations, and 3) to evaluate the pharmacokinetic profile of the drug when administered as SD, in humans. The solubility of FPN in water and dissolution media was evaluated as a function of HPbetaCD concentration. The SD was prepared by coevaporation from dilute aqueous NH3 and evaluated in rats. The release of the drug from tablet formulations and capsules of SD was studied in simulated gastric fluid and phosphate buffer, pH 7.2. The bioavailability of drug when administered as SD was evaluated in humans. HPbetaCD enhanced the solubility of the drug, and SD improved bioavailability and reduced ulcerogenicity of the drug in rats. The type of excipient used affected drug release from tablets. Presence of microcrystalline cellulose, a hydrophilic polymeric excipient, resulted in uptake of water and stabilization of the resulting gels-like structure of HPbetaCD-containing tablets. This adversely affected drug release. The release from capsules filled with SD was comparable to that obtained from plain SD powder. The drug-HPbetaCD association constant in water was much lower than the values reported in literature. The bioavailability (which could suffer in case of higher association constant) was enhanced on administration of SD-filled capsules to humans.

Development of Fast-Dissolving Tablets of Flurbiprofen-Cyclodextrin Complexes

The present study was aimed at developing a tablet formulation based on an effective flurbiprofen-cyclodextrin system, able to allow a rapid and complete dissolution of this practically insoluble drug. Three different cyclodextrins were evaluated: the parent beta-cyclodextrin (previously found to be the best partner for the drug among the natural cyclodextrins), and two amorphous, highly soluble beta-cyclodextrin derivatives, i.e., methyl-beta-cyclodextrin and hydroxyethyl-beta-cyclodextrin. Equimolar drug-cyclodextrin binary systems prepared according to five different techniques (physical mixing, kneading, sealed-heating, coevaporation, and colyophilization) were characterized by Differential Scanning Calorimetry, x-ray powder diffractometry, infrared spectroscopy, and optical microscopy and evaluated for solubility and dissolution rate properties. The drug solubility improvement obtained by the different binary systems varied from a minimum of 2.5 times up to a maximum of 120 times, depending on both the cyclodextrin type and the system preparation method. Selected binary systems were used for preparation of direct compression tablets with reduced drug dosage (50 mg). Chitosan and spray-dried lactose, alone or in mixture, were used as excipients. All formulations containing drug-cyclodextrin systems gave a higher drug dissolved amount than the corresponding ones with drug alone (also at a dose of 100 mg); however, the drug dissolution behavior was strongly influenced by formulation factors. For example, for the same drug-cyclodextrin product the time to dissolve 50% drug varied from less than 5 minutes to more than 60 minutes, depending on the excipient used for tableting. In particular, only tablets containing the drug kneaded with methyl-beta-cyclodextrin or colyophilized with beta-cyclodextrin and spray-dried lactose as the only excipient satisfied the requirements of the Food and Drug Administration (FDA) for rapid dissolving tablets, allowing more than 85% drug to be dissolved within 30 minutes. Finally, it can be reasonably expected that the obtained drug dissolution rate improvement will result in an increase of its bioavailability, with the possibility of reducing drug dosage and side effects.

Dissolution, Solubility, XRD, and DSC Studies on Flurbiprofen-Nicotinamide Solid Dispersions

Flurbiprofen-nicotinamide solid dispersions were prepared by the fusion method. The solid dispersions were evaluated for dissolution rate. The drug-carrier interaction in the liquid and solid states were studied by using phase solubility analysis, phase diagram, X-ray diffraction (XRD), and differential scanning calorimentry (DSC). Solid dispersions gave fast and rapid dissolution of flurbiprofen compared with the pure drug and the physical mixture. Phase diagram and DSC indicated that flurbiprofen and nicotinamide form a eutectic mixture. The aqueous solubility of flurbiprofen was enhanced in the presence of nicotinamide.

New form discovery for the analgesics flurbiprofen and sulindac facilitated by polymer-induced heteronucleation

The selection and discovery of new crystalline forms is a longstanding issue in solid-state chemistry of critical importance because of the effect molecular packing arrangement exerts on materials properties. Polymer-induced heteronucleation has recently been developed as a powerful approach to discover and control the production of crystal modifications based on the insoluble polymer heteronucleant added to the crystallization solution. The selective nucleation and discovery of new crystal forms of the well-studied pharmaceuticals flurbiprofen (FBP) and sulindac (SUL) has been achieved utilizing this approach. For the first time, FBP form III was produced in bulk quantities and its crystal structure was also determined. Furthermore, a novel 3:2 FBP:H(2)O phase was discovered that nucleates selectively from only a few polymers. Crystallization of SUL in the presence of insoluble polymers facilitated the growth of form I single crystals suitable for structure determination. Additionally, a new SUL polymorph (form IV) was discovered by this method. The crystal forms of FBP and SUL are characterized by Raman and FTIR spectroscopies, X-ray diffraction, and differential scanning calorimetry.

Chemical shift computations on a crystallographic basis: some reflections and comments

Computations for chemical shifts of molecular organic compounds using the gauge-including projector augmented wave method and the NMR-CASTEP code are reviewed. The methods are briefly introduced, and some general aspects involving the sources of uncertainty in the results are explored. The limitations are outlined. Successful applications of the computations to problems of interpretation of NMR results are discussed and the range of areas in which useful information is obtained is illustrated by examples. The particular value of the computations for comparing shifts between resonances where the same chemical site is involved is emphasised. Such cases arise for shifts between different crystallographically independent molecules of the same chemical species, between polymorphs and for shift anisotropies and asymmetries.

Asymmetric membrane capsule for osmotic delivery of flurbiprofen

An asymmetric membrane capsule of cellulose acetate for osmotic delivery of flurbiprofen has been developed and influence of osmogents and solubilizing agent on in vitro drug release were evaluated. The capsule membrane was prepared by the phase inversion technique. To ensure the osmotic delivery of drug, two approaches were adopted: (i) the drug was encapsulated with osmogents like sodium chloride and mannitol to increase the osmotic pressure of the core, and (ii) the drug was encapsulated with sodium lauryl sulfate in the core of the formulation to increase the solubility and thus its osmotic pressure. Scanning electron microscopy of the membrane confirmed its porous, dense asymmetric nature. Dye test revealed in situ pore formation. The in vitro release study showed that as the proportion of osmogent and solubilizing agent was increased the release rate also increased. A good correlation was observed between the zero-order rate constant and the amount of the osmogent and solubilizing agent used.