Evaluation of the in vitro human skin percutaneous absorption of ketoprofen in topical anhydrous and aqueous gels.

BACKGROUND: Ketoprofen is a nonsteroidal anti-inflammatory drug used for the treatment of acute and chronic pain associated with inflammatory conditions. This study aims to evaluate the in vitro percutaneous absorption of ketoprofen 10% formulated in proprietary anhydrous and aqueous gels using the Franz skin finite dose model. MATERIALS AND METHODS: The anhydrous gel was initially characterized for cytotoxicity using EpiDerm skin tissue model by cell proliferation assay and Western blot analysis. The Ultra Performance Liquid Chromatography method for measuring ketoprofen was validated and the stability of ketoprofen 10% in the anhydrous gel formulation was evaluated at 5°C and 25°C for 181 days. The percutaneous absorption of ketoprofen was determined using donated human skin. The tissue sections were mounted within Franz diffusion cells. A variable finite dose of each ketoprofen formulation in either anhydrous or aqueous gel was applied to the skin sections and receptor solutions were collected at various time points. RESULTS: Cell proliferation assay showed minimal cell death when EpiDerm skin tissue was exposed to the anhydrous gel for 24 h; the levels of protein markers of cell proliferation were not affected after 17-h exposure. Ketoprofen was stable in the anhydrous gel when stored at 5°C and 25°C. When compounded in the anhydrous and aqueous gels, ketoprofen had mean flux rate of 2.22 and 2.50 µg/cm2 /h, respectively, after 48 h. The drug was distributed to the epidermis and dermis sections of the skin. Both the anhydrous and aqueous gels facilitated the percutaneous absorption of ketoprofen without statistically significant differences. CONCLUSION: The anhydrous gel can be used as a base to facilitate the transdermal delivery of ketoprofen. Although the anhydrous and aqueous gels can deliver a similar amount of ketoprofen, the anhydrous gel (water activity below 0.6) allows for extended default beyond-use-date of compounding preparations.

Ketoprofen exposure perturbs nitrogen assimilation and ATP synthesis in rice roots: An integrated metabolome and microbiome analysis.

Ketoprofen, a commonly used non-steroidal anti-inflammatory drug (NSAID), can enter farmland environments via sewage irrigation and manure application and is toxic to plants. However, there have been relatively few studies on the association of ketoprofen with nitrogen (N) assimilation and metabolic responses in plants. Accordingly, the goal of this study was to investigate the effects of ketoprofen on ATP synthesis and N assimilation in rice roots. The results showed that with increasing ketoprofen concentration, root vitality, respiration rate, ATP content, and H+-ATPase activity decreased and plasma membrane permeability increased. The expressions of OSA9, a family III H+-ATPase gene, and OSA6 and OSA10, family IV genes, were upregulated, indicating a response of the roots to ketoprofen. Nitrate, ammonium, and free amino acids content decreased with increased ketoprofen. The levels of enzymes involved in N metabolism, namely nitrate reductase, nitrite reductase, glutamine synthetase, glutamate synthetase, and glutamate dehydrogenase, also decreased under ketoprofen treatment. Principal component analysis revealed that ketoprofen treatment can significantly affect energy synthesis and nitrogen assimilation in rice roots, while these effects can be alleviated by the antioxidant response. Most of the metabolite contents increased, including amino acids, carbohydrates, and secondary metabolites. Key metabolic pathways, namely substance synthesis and energy metabolism, were found to be disrupted. Microbiome analysis showed that community diversity and richness of rice root microorganisms in solution increased with increasing levels of ketoprofen treatment, and the microbial community structure and metabolic pathways significantly changed. The results of this study provides new insights into the response of rice roots to ketoprofen.

Biocompatible phospholipid-based nanovesicular drug delivery system of ketoprofen: Systematic development, optimization, and preclinical evaluation.

The present work involved development of phospholipid-based permeation enhancing nanovesicles (PENVs) for topical delivery of ketoprofen. Screening of phospholipids and process parameters was performed. Central composite design was used for optimization of factors, that is, amount (%, w/w) of phospholipid and ethanol at three levels. The optimized nanovesicles (NVs) were loaded with different terpenes and then incorporated into a gel base. Optimized NVs exhibited 69% entrapment efficiency, 51% transmittance, 328 nm mean vesicle size, and polydispersity index of 0.25. In vitro release kinetics evaluation indicated best fitting as per Korsemeyer-Peppa's model and drug release via Fickian-diffusion mechanism. The optimized NVs loaded with mint terpene showed minimal degree of deformability and maximal elasticity as compared with the conventional NVs and liposomes. Rheology and texture analysis indicated pseudoplastic flow and smooth texture of the vesicle gel formulation. Ex vivo permeation studies across Wistar rat skin indicated low penetration (0.43-fold decrease) and high skin retention (4.26-fold increase) of ketoprofen from the optimized PENVs gel vis-à-vis the conventional gel. Skin irritancy study indicated lower scores for PENVs gel construing its biocompatible nature. Stability studies confirmed cold storage is best suitable for vesicle gel, and optimized PENVs were found to be suitable for topical delivery of ketoprofen.

Synthesis and Preclinical Evaluation of 18F-Labeled Ketoprofen Methyl Esters for Cyclooxygenase-1 Imaging in Neuroinflammation.

Cyclooxygenase (COX) is a rate-limiting enzyme in the synthesis of proinflammatory prostanoids from arachidonic acid. In vivo imaging of COX by PET is a potentially powerful tool for assessing the inflammatory response to injury, infection, and disease. We previously reported on a promising PET probe for COX imaging, 11C-labeled ketoprofen methyl ester, which can detect COX-1 activation in models of neuroinflammation and neurodegenerative disorders. In the current study, we aimed to design a fluorine-substituted benzoyl group of ketoprofen (FKTP) and to evaluate its racemate and enantiomers (18F-labeled ketoprofen methyl ester, [18F]FKTP-Me) as PET proradiotracers, potential radiopharmaceuticals for in vivo PET study of COX-1. Methods: We performed nucleophilic aromatic 18F-fluorination to obtain the desired racemic radiolabeled probe, (RS)-[18F]FKTP-Me, at a radiochemical yield of 11%-13%. Subsequent high-performance liquid chromatography separation with a chiral column yielded the desired enantiomerically pure (R)- and (S)-[18F]FKTP-Me. We examined the in vivo properties of (RS)-, (R)-, and (S)-[18F]FKTP-Me in PET studies using rats in which hemispheric inflammation was induced by intrastriatally injecting a lipopolysaccharide. Results: Racemic (RS)-[18F]FKTP-Me and enantiomeric (R)- or (S)-[18F]FKTP-Me were synthesized with radiochemical and chemical purities of more than 99%. The metabolite analysis revealed that the racemic (RS)-[18F]FKTP-Me crossed the blood-brain barrier and entered the brain, where it was subsequently hydrolyzed to its pharmacologically active acid form. PET images revealed a high accumulation of (R)-, (S)-, and (RS)-[18F]FKTP in the inflamed regions in rat brain. Moreover, the accumulated radioactivity of (S)-[18F]FKTP-Me was higher than that of (RS)-[18F]FKTP-Me and (R)-[18F]FKTP-Me, which was correlated with the stereospecific inhibitory activity of FKTP against COX-1. Conclusion: From the results of this study, we conclude that racemic (RS)-[18F]FKTP-Me and its enantiomers could act as proradiotracers of neuroinflammation in rat brain by the association of their hydrolyzed acid forms with COX-1 in inflamed regions. In particular, (S)-[18F]FKTP-Me demonstrated suitable properties as a COX-1-specific probe in PET imaging of neuroinflammation.

Production of lipophilic nanogels by spontaneous emulsification.

Nanosized gel particles, so-called nanogels, have attracted substantial interest in different application fields, thanks to their controllable and three-dimensional physical structure, good mechanical properties and potential biocompatibility. Literature reports many technologies for their preparation and design, however a recurrent limitation remains in their broad size distributions as well as in the poor size control. Therefore, the monodisperse and size-controlled nanogels preparation by simple process -like emulsification- is a real challenge still in abeyance to date. In this study we propose an original low energy emulsification approach for the production of monodisperse nanogels, for which the size can be finely controlled in the range 30 to 200 nm. The principle lies in the fabrication of a direct nano-emulsion containing both oil (medium chain triglycerides) and a bi-functional acrylate monomer. The nanogels are thus formed in situ upon UV irradiation of the droplet suspension. Advantage of such modification of the oil nano-carriers are the potential modulation of the release of encapsulated drugs, as a function of the density and/or properties of the polymer chain network entrapped in the oil nano-droplets. This hypothesis was confirmed using a model of hydrophobic drug -ketoprofen- entrapped into the nanogels particles, along with the study of the release profile, carried out in function of the nature of the monomers, density of polymer chains, and different formulation parameters.

Human Serum Albumin Aggregation/Fibrillation and its Abilities to Drugs Binding.

Human serum albumin (HSA) is a protein that transports neutral and acid ligands in the organism. Depending on the environment's pH conditions, HSA can take one of the five isomeric forms that change its conformation. HSA can form aggregates resembling those in vitro formed from amyloid at physiological pH (neutral and acidic). Not surprisingly, the main goal of the research was aggregation/fibrillation of HSA, the study of the physicochemical properties of formed amyloid fibrils using thioflavin T (ThT) and the analysis of ligand binding to aggregated/fibrillated albumin in the presence of dansyl-l-glutamine (dGlu), dansyl-l-proline (dPro), phenylbutazone (Phb) and ketoprofen (Ket). Solutions of human serum albumin, both non-modified and modified, were examined with the use of fluorescence, absorption and circular dichroism (CD) spectroscopy. The experiments conducted allowed observation of changes in the structure of incubated HSA (HSAINC) in relation to nonmodified HSA (HSAFR). The formed aggregates/fibrillation differed in structure from HSA monomers and dimers. Based on CD spectroscopy, previously absent ßstructural constructs have been registered. Whereas, using fluorescence spectroscopy, the association constants differing for fresh and incubated HSA solutions in the presence of dansyl-amino acids and markers for binding sites were calculated and allowed observation of the conformational changes in HSA molecule.

Structural investigations of stereoselective profen binding by equine and leporine serum albumins.

Serum albumin, the most abundant transport protein of mammalian blood, interacts with various nonsteroidal anti-inflammatory drugs (NSAIDs) affecting their disposition, metabolism, and excretion. A big group of chiral NSAIDs transported by albumin, profens, is created by derivatives of 2-arylpropionic acid. The chiral center in the structures of profens is adjacent to the carboxylate moiety and often determines different pharmacological properties of profen enantiomers. This study describes crystal structures of two albumins, isolated from equine and leporine serum, in complexes with three profens: ibuprofen, ketoprofen, and suprofen. Based on three-dimensional structures, the stereoselectivity of albumin is discussed and referred to the previously published albumin complexes with drugs. Drug Site 2 (DS2) of albumin, the bulky hydrophobic pocket of subdomain IIIA with a patch of polar residues, preferentially binds (S)-enantiomers of all investigated profens. Almost identical binding mode of all these drugs clearly indicates the stereoselectivity of DS2 towards (S)-profens in different albumin species. Also, the affinity studies show that DS2 is the major site that presents high affinity towards investigated drugs. Additionally, crystallographic data reveal the secondary binding sites of ketoprofen in leporine serum albumin and ibuprofen in equine serum albumin, both overlapping with previously identified naproxen binding sites: the cleft formed between subdomains IIIA and IIIB close to the fatty acid binding site 5 and the niche created between subdomains IIA and IIIA, called fatty acid site 6.

A new gastro-intestinal mathematical model to study drug bioavailability.

This work focuses on a new mathematical model which describes the gastro-intestinal absorption of drugs and the effect of food interactions on drugs bioavailability. The model structure consists of five compartments (stomach, duodenum, jejunum feeding, intestine and blood) simulated though different in-series reactors. All the enzymatic reactions taking place in the gastro-intestinal system are described through the Michaelis-Menten kinetic equations. The model has been tested for drug administration (paracetamol and ketoprofen) with and without the meal digestion. The model has been validated through pharmacokinetics curves obtained from in vivo tests (reported in the literature) and used to simulate the drug absorption dynamics in different conditions. The maximum blood concentration were 0.153 mmol L-1 and 0.0243 mmol L-1, respectively for paracetamol and ketoprofen. The time to reach the maximum concentration for the paracetamol and ketoprofen was around 55 min. In case of contemporary meal digestion, the maximum concentration of paracetamol in the blood was 0.100 mmol L-1 and 0.0135 mmol L-1 for ketoprofen; the time to reach the maximum concentration was 3 h and 45 min for paracetamol and 3 h and 35 min for ketoprofen. The drugs showed different pharmacokinetics, in agreement with the literature, during the digestion of food. To show the predictive capacity of the model, the simulations were also compared against additional experimental data (obtained from in vivo tests available in the literature) relative to ketoprofen administration with food.

Stereoselectivity evaluation of chiral chitosan microspheres delivery system containing rac-KET in vitro and in vivo.

The influence of chiral excipient D-chitosan (CS) on the stereoselective release of racemic ketoprofen (rac-KET) microspheres has been investigated in comparison to those microspheres containing individual enantiomers in vitro and in vivo. Stereoselectivity was observed in vitro release test, with R-KET release slightly higher than that of S-KET, especially in 3% rac-KET loading microspheres. Stereoselectivity is dependent on the content of chiral excipient and pH of release medium. A molecular docking study between CS and KET enantiomers further revealed that S-KET has a stronger interaction with CS compared to R-KET. Moreover, the plasma concentration of KET enantiomers in rats shows substantial differences, as the plasma levels of S-KET were higher than those of R-KET. Plasma levels of enantiomers from the R-KET microspheres had similar stereoselectivity as rac-KET microspheres. The S/R ratio of rac-KET microspheres was significantly lower than that of rac-KET suspension (regular-release formulation) (p<.05), and the differences is 3-5 fold. Besides, rates of R-KET converted to S-KET exhibited differences between rac-KET microspheres and suspension. Similar results were also found between R-KET microspheres and suspension. All investigations suggest that the chitosan interacting preferentially with S-KET to R-KET significantly affect the stereoselective pharmacokinetics of rac-KET from chitosan microspheres in rats.

Mechanisms and quantification of adsorption of three anti-inflammatory pharmaceuticals onto goethite with/without surface-bound organic acids.

Nowadays non-steroidal anti-inflammatory drugs (NSAIDs) are often detected in surface water and groundwater. In this study, effects of environmental factors, i.e., solution pH, ionic strength, temperature and surface-bound organic acids, on bonding of three typical NSAIDs (ketoprofen, naproxen and diclofenac) onto goethite were systematically investigated. Column chromatography, batch experiments, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and surface complexation modeling were used to probe the adsorption mechanisms. Bonding of three NSAIDs onto goethite was totally reversible, ionic strength-dependent and endothermic (adsorption enthalpy 2.86-9.75 kJ/mol). These evidences supported H-bonding mechanism, which was further explained by ATR-FTIR observation and a triple planes model. Surface-bound organic acids (phthalic acid, trimellitic acid and pyromellitic acid) by inner-sphere complexation with goethite were hard to be desorbed. Surface-bound phthalic acid increased the uptake of NSAIDs but surface-bound trimellitic acid and pyromellitic acid reduced their adsorption. The reason is that the adsorbed phthalic acid can result in a more hydrophobic surface while adsorbed trimellitic acid and pyromellitic acid increased the surface negative charge and polarity. Finally, adsorption of NSAIDs onto goethite with/without surface-bound organic acids was well described by a free energy model, in which contributions of interactions (e.g., H-bonding and van der Waals) were evaluated.

Hyaluronic acid gel-core liposomes (hyaluosomes) enhance skin permeation of ketoprofen.

Since FDA approval of the first transdermal patch in 1979, the utilizing of skin as a route of systemic drug administration has attracted the attention of the formulation scientists. The liposomes research in the area of transdermal drug delivery has been around for decades. This study aimed at comparing the latest gel-core liposomes (hyaluosomes) with nonconventional liposomal systems such as propylene glycol (PG)-liposomes, ethosomes, transferosomes and conventional liposomes loaded with ketoprofen. The modified thin-film hydration method was used to prepare these liposomal systems; size, zeta potential, EE%, TEM, rheological properties, in vitro release and ex vivo permeation studies were performed. Vesicle size and PDI ranged from 160 nm to 700 nm and 0.15 to 0.5, respectively. More interestingly, thermal gelation and shear-thinning characteristics were only recorded with hyaluosomes; while Newtonian behavior and low viscosity values (2 mPas.s to 6 mPa.s) were shown with all other liposomal systems. Hyaluosomes recorded superior (3-fold increases) transdermal permeation characteristics (flux and permeability coefficient), compared with other liposomal systems. With the advancement in liposomal sciences, this study warrants hyaluosomes as a promising transdermal liposomal system for favorable rheological characteristics as well as superior transdermal permeation that proved greater capacity than conventional and other non-conventional liposomal systems.

Identification of human, rat and mouse hydrolyzing enzymes bioconverting amino acid ester prodrug of ketoprofen.

Alkyl ester prodrugs are well known to be bioconverted by carboxylesterases, particularly in rodents' by first-pass metabolism in the systemic circulation and liver. However, the bioconversion of structurally more complex esters with polar functional groups is less well understood, especially in humans. Therefore, it is not clear if ester prodrugs can be utilized for targeted drug delivery. In the present study a brain-targeted ester prodrug (1) of ketoprofen, utilizing the l-type amino acid transporter 1 (LAT1) was prepared and the enzymes involved in its metabolism in human plasma and liver S9 subcellular fraction as well as rat brain S9 fraction were identified. Furthermore, species differences among mouse, rat and human plasma and liver S9 fraction were compared. The results showed that bioconversion of the ester prodrug was much faster in mouse plasma compared to human, while it's half-life in rat plasma was closer to the one of human. Moreover, both rodent species showed more efficient bioconversion in the liver S9 fractions compared to human and relatively efficient bioconversion in the brain S9 fractions. More specifically, butyrylcholinesterase (BChE) and paraoxygenase 1 (PON1) were the main hydrolyzing enzymes of the prodrug 1 in human plasma, while carboxylesterases 1 and 2 (CES1 and CES2) as well as PONs were the main bioconverting enzymes in human liver S9 fractions. In rat brain S9 fraction, acetylcholinesterase (AChE) was hydrolyzing the prodrug 1, although also other unidentified metal-and pH-dependent enzyme(s) were recognized to be participating to the total bioconversion of the compound 1 in the brain.

Chronotherapeutic Drug Delivery of Ketoprofen and Ibuprofen for Improved Treatment of Early Morning Stiffness in Arthritis Using Hot-Melt Extrusion Technology.

This work developed a chronotherapeutic drug delivery system (CTDDS) utilizing a potential continuous hot-melt extrusion (HME) technique. Ketoprofen (KTP) and ibuprofen (IBU) were used as two separate model drugs. Eudragit S100 (ES100) was the matrix-forming agent, and ethyl cellulose (EC) (2.5 and 5%) was the release-retarding agent. A 16-mm extruder was used to develop the CTDDS to pilot scale. The obtained extrudate strands were transparent, indicating that the drugs were homogeneously dispersed in the matrix in an amorphous form, confirmed by both differential scanning calorimetry and powder X-ray diffraction. The strands were pelletized into 1, 2, and 3 mm size pellets. A 100% drug release from 1, 2, and 3 mm pellets with 2.5% EC was observed at 12, 14, and 16 h, whereas the drug release was sustained for 14, 16, and 22 h from 5% EC pellets, respectively, for KTP. The release characteristics of IBU were similar to those of KTP with modest variations in release at lag time. The in vitro drug release study conducted in three-stage dissolution media showed a desired lag time of 6 h. The percent drug release from 1, 2, and 3 mm pellets with 40% drug load showed < 20% release from all formulations at 6 h. The amount of ethyl cellulose and pellet size significantly affected drug release. Formulations of both KTP and IBU were stable for 4 months at accelerated stability conditions of 40°C/75% RH. In summary, HME is a novel technique for developing CTDDS.

Biodegradable Ingredient-Based Emulgel Loaded with Ketoprofen Nanoparticles.

Biodegradable materials are extensively employed to design nanocarriers that mimic extracellular environment in arthritis. The aim of this study was to formulate and characterize biocompatible, biodegradable ketoprofen-loaded chitosan-chondroitin sulfate (CHS-CS) nanoparticles with natural ingredients for transdermal applications. Polymers used in the design of nanocarriers are biodegradable and produce synergistic anti-inflammatory effect for the treatment of arthritis. For transdermal application, argan oil-based emulgel is utilized to impart viscosity to the formulation. Furthermore, naturally occurring argan oil synergizes anti-inflammatory effect of formulation and promotes skin penetration. CHS and CS form nanoparticles by polyelectrolyte complex formation or complex coacervation at pH 5.0. These particles were loaded into argan oil-based emulgel. Employing this method, nanoparticles were formulated with particle size in the range of 300-500 nm. These nanocarriers entrapped ketoprofen and showed more than 76% encapsulation efficiency and 77% release of the ketoprofen at pH 7.4 within 72 h. Drug releases from CHS-CS nanoparticles by mechanism of simple diffusion. Nanoparticle-loaded argan oil emulgel significantly enhanced skin penetration of ketoprofen as compared to marketed gel (p < 0.05). Nanocarriers prepared successfully delivered drug through transdermal route using natural ingredients. Graphical abstract ᅟ.

Long-term exposure of Mytilus galloprovincialis to diclofenac, Ibuprofen and Ketoprofen: Insights into bioavailability, biomarkers and transcriptomic changes.

Non-steroidal anti-inflammatory drugs (NSAIDs) represent a growing concern for marine ecosystems due to their ubiquitous occurrence and documented adverse effects on non-target organisms. Despite the remarkable efforts to elucidate bioaccumulation and ecotoxicological potential under short-term conditions, limited and fragmentary information is available for chronic exposures. In this study bioavailability, molecular and cellular effects of diclofenac (DIC), ibuprofen (IBU) and ketoprofen (KET) were investigated in mussels Mytilus galloprovincialis exposed to the realistic environmental concentration of 2.5 µg/L for up to 60 days. Results indicated a significant accumulation of DIC and IBU but without a clear time-dependent trend; on the other hand, KET concentrations were always below the detection limit. Analyses of a large panel of molecular, biochemical and cellular biomarkers highlighted that all investigated NSAIDs caused alterations of immunological parameters, genotoxic effects, modulation of lipid metabolism and changes in cellular turn-over. This study provided the evidence of long-term ecotoxicological potential of NSAIDs, further unraveling the possible hazard for wild marine organisms.

Relevance and bio-catalytic strategies for the kinetic resolution of ketoprofen towards dexketoprofen.

This review presents the most relevant investigations concerning the biocatalytic kinetic resolution of racemic ketoprofen to dexketoprofen for the last 22 years. The advantages related to the administration of the dex-enantiomer in terms of human health, the so called "chiral switch" in the pharmaceutical industry and the sustainability of biotransformations have been the driving forces to develop innovative technology to obtain dexketoprofen. In particular, the kinetic resolution of racemic ketoprofen through enantiomeric esterification and hydrolysis using lipases as biocatalysts are thoroughly revised and commented upon. In this context, the biocatalysts, acyl-acceptors (alcohols), reaction conditions, conversion, enantiomeric excess, and enantiomeric ratio among others are discussed. Moreover, the investigations concerning scaling up processes in order to obtain an optically pure enantiomer of the profen are presented. Finally, some guidelines about perspectives of the technology and research opportunities are given.

Cooperativity effect involving drug-DNA/RNA intermolecular interaction: A B3LYP-D3 and MP2 theoretical investigation on ketoprofen⋯cytosine⋯H2O system.

In order to examine the origin of the drug action and design new DNA/RNA-targeted drugs, the cooperativity effect involving drug-DNA/RNA intermolecular interaction in ketoprofen⋯cytosine⋯H2O ternary system were investigated by the B3LYP, B3LYP-D3, and MP2 methods with the 6-311++G(2d,p) basis set. The thermodynamic cooperativity was also evaluated at 310.15 K. The N-H⋯O, O-H⋯O, O-H⋯N, C-H⋯N, and C-H⋯O H bonds coexist in ternary complexes. The intermolecular interactions obtained by B3LYP-D3 are close to those calculated by MP2. The steric effects and van der Waals interactions have little influence on the cooperativity effects. The anti-cooperativity effect in ket⋯cyt⋯H2O is far more notable than the cooperativity effect, and the stability of the cyclic structure with anti-cooperativity effect is higher than that of the linear structure with cooperativity effect, as is confirmed by the AIM (atoms in molecules) and RDG (reduced density gradient) analysis. Thus, it can be inferred that, in the presence of H2O, the anti-cooperativity effect plays a dominant role in the drug-DNA/RNA interaction, and the nature of the hydration in the binding of drugs to DNA/RNA bases is the H-bonding anti-cooperativity effect. Furthermore, the drug always links simultaneously with DNA/RNA base and H2O, and only in this way can the biological activity of drugs play a role. In most cases, the enthalpy change is the major factor driving the cooperativity, as is different from most of biomacromolecule complexes.

Correlation between glucuronidation and covalent adducts formation with proteins of nonsteroidal anti-inflammatory drugs.

Nonsteroidal anti-inflammatory drugs (NSAIDs) can cause idiosyncratic liver injury. Mechanisms involved in NSAID-induced liver injury are complex. Previous studies have suggested that acyl glucuronide of NSAIDs (NSAIDs-Glu) plays an important role in the development of liver injury via covalently binds to proteins and the resultant adduct induces immunological toxicity. As only some NSAIDs-Glu are commercially available, the evaluation of covalent protein adduct formation using ready-made NSAIDs-Glu is difficult and inconvenient. Moreover, glucuronidation potency varies with the NSAID, including stereoisomers. Therefore, in this study, we simultaneously examined the glucuronidation and covalent adduct formation using enantiomers of parent NSAIDs (ibuprofen, naproxen, pranoprofen, ketoprofen, and flurbiprofen) in rat liver microsomes. Glucuronides and covalent adducts were quantified by HPLC. The amount of covalent adduct increased with NSAIDs-Glu formation in the rat liver microsomes in a time-dependent manner. A significant positive correlation was observed between the AUC of NSAIDs-Glu and that of covalent adduct, except ketoprofen. Although ketoprofen exhibited the highest glucuronidation rate among the NSAIDs investigated, the amount of covalent adduct was similar to that for pranoprofen, which had the lowest glucuronidation rate. Thus, it may be difficult for ketoprofen glucuronide to covalently bind with proteins in the rat liver microsomes. Our results suggested that the amount of glucuronide formed is a key factor in predicting covalent bond formation with protein in NSAIDs, in addition to degradability and bindability with proteins of NSAIDs-Glu. Further studies are required to confirm the relationship between the tendency of glucuronidation and the formation of covalent adducts of NSAIDs.

Continuous transformation of chiral pharmaceuticals in enzymatic membrane bioreactors for advanced wastewater treatment.

This study demonstrates continuous enantiomeric inversion and further biotransformation of chiral profens including ibuprofen, naproxen and ketoprofen by an enzymatic membrane bioreactor (EMBR) dosed with laccase. The EMBR showed non-enantioselective transformations, with high and consistent transformation of both (R)- and (S)-ibuprofen (93 ± 6%, n = 10), but lower removals of both enantiomers of naproxen (46 ± 16%, n = 10) and ketoprofen (48 ± 17%, n = 10). Enantiomeric analysis revealed a bidirectional but uneven inversion of the profens, for example 14% inversion of (R)- to (S)- compared to 4% from (S)- to (R)-naproxen. With redox-mediator addition, the enzymatic chiral inversion of both (R)- and (S)-profens remained unchanged, although the overall conversion became enantioselective; except for (S)-naproxen, the addition of redox mediator promoted the degradation of (R)-profens only.

Comparison of segmental-dependent permeability in human and in situ perfusion model in rat.

Nowadays, alternative methods have been developed to predict intestinal permeability values in human as in vitro, in situ or ex vivo methods. They were developed by the necessity to avoid the problems of the human permeability experiments. However, determination of human permeability is needed to properly validate the alternative methods. For this reason, recently, Dahlgren et al. published an indirect method based on a deconvolution technique to estimate the human permeability in different gastrointestinal segments (jejunum, ileum and colon). Therefore, the objective of this research was to demonstrate that Doluisio technique is a useful method to predict the human permeability in different gastrointestinal segments. To achieve this goal, the rat permeability in different segments, of the same drugs studied by Dahlgren et al. (atenolol, metoprolol and ketoprofen), have been compared with the human data obtained by the deconvolution method. The results obtained in this work show that the Doluisio method is a reliable tool to predict segmental human permeability. Consequently, the deconvolution method can be employed to build an extensive database of human permeability, overall from ileum and colon, because there is a lack of human permeability data of these distal segments. Once there are enough human data available, the Doluisio technique will be a valuable alternative method to predict the permeability of new molecules with therapeutic activity without the requirement of human experiments.