Mohamed Skiba

An α-Linolenic Acid-Rich Formula Reduces Oxidative Stress and Inflammation by Regulating NF-κB in Rats with TNBS-Induced Colitis

We have previously shown that α-linolenic acid (ALA), a (n-3) PUFA exerts in vitro antiinflammatory effects in the intestine. In this study, we aimed to evaluate its effect on inflammatory and oxidative stress in a colitis model. Colitis was induced in 2 groups at d 0 by intrarectal injection of 2-4-6-trinitrobenzen sulfonic acid (TNBS), whereas the control group received the vehicle. Rats we fed 450 mg . kg(-1) . d(-1) of ALA (TNBS+ALA) while the other colitic group (TNBS) and the control group were fed an isocaloric corn oil formula for 14 d (from d -7 to d 7). RBC fatty acid composition was assessed. Oxidative stress was studied by measuring urinary 8-isoprostanes (8-IP) and colon glutathione (GSH) concentration and inducible nitric oxide synthase (iNOS) expression. Colitis was assessed histologically, by production of proinflammatory mediators, including cytokines, leukotrienes B(4) (LTB(4)), and cyclooxygenase-2 (COX-2) and by nuclear factor-κB (NF-κB) activation. The ALA-rich diet significantly increased the RBC levels of ALA, eicosapentaenoic acid, and docosapentaenoic acid (n-3) compared with the TNBS group (P < 0.01 for all). The beneficial effect of ALA supplementation on oxidative stress was reflected by lower urinary 8-IP levels (P < 0.05), a normalized colon GSH concentration (P < 0.01), and reduced colon iNOS expression (P < 0.05) compared with the TNBS group. ALA also protected against colon inflammation as assessed by lower tumor necrosis factor-α secretion and mRNA level (P < 0.05), reduced NF-κB activation (P = 0.01), and lower colon lipid mediator concentrations such as LTB(4) and COX-2 (P < 0.05) compared with the TNBS group. These findings show that an ALA-rich formula is beneficial to TNBS-induced colitic rats via inhibition of oxidative and inflammatory stress.

Stability assessment of ketoconazole in aqueous formulations.

Ketoconazole is an imidazole antifungal agent. It has a wide antifungal spectrum and possesses some antibacterial activity. In inappropriate formulations, especially in aqueous media, ketoconazole molecules may be unsteady. The stability of ketoconazole in aqueous media was assessed as a function of pH, antioxidant and ketoconazole concentrations. It was found that ketoconazole was least stable at pH 1 among the pH values studied (pH 1-9). Since the major degradation pathway was specific acid catalysis, based upon the transition-state theory, the entropy (DeltaS) of the activation was calculated and found to be negative indicating that the activated complex was more constrained than the individual species. The free energy of activation (DeltaG) was estimated to be 30 kcal mol(-1). The viscosity of the formulation was found to be more stable at high pH because carbopol is stable at basic pH and protected ketoconazole. It appears that the amount of ketoconazole in the formulation has a low influence on the degradation mechanisms. The increase of the butylated hydroxytoluene antioxidant levels from 0.05 to 0.4%, adversely affected the stability of ketoconazole. In conclusion, the expected shelf life of the final ketoconazole formulation (pH 7, 0.1% butylated hydroxytoluene) was 15 months.

Solubility and Dissolution Rate of Progesterone-Cyclodextrin-Polymer Systems

ABSTRACT This contribution focused on the solubility improvement of the poorly water-soluble steroid hormone progesterone which, in its natural state, presents a reduced oral bioavailability. In the first part of this study, two simple, reproducible methods that were candidates for use in the preparation of inclusion complexes with cyclodextrins were investigated. Solubility capacities of the progesterone complex with hydroxypropyl-β-CD (HPβ-CD), hydoxypropyl-γ-CD (HPγ-CD), permethyl-β-CD (PMβ-CD), and sulfobutylether-β-CD (SBEβ-CD), prepared by the freeze-drying and precipitation methods, were evaluated by Higuchi phase solubility studies. The results showed that HPβ-CD and PMβ-CD were the most efficient among the four cyclodextrins for the solubilization of progesterone, with the highest apparent stability constants. Therefore, dissolution studies were conducted on these latest progesterone/cyclodextrin complexes and physical mixtures. Two additional natural cyclodextrins, β-CD and γ-CD, were taken as references. Hence, the influence of more highly soluble derivatives of β‐CD (HPβ-CD, PMβ-CD) on the progesterone dissolution rate, in comparison to pristine β-CD, alongside an increase in the cavity width for γ-CD versus β-CD, were investigated. The dissolution kinetics of progesterone dissolved from HPβ-CD, PMβ-CD, and γ-CD revealed higher constant rates in comparison to β-CD. Therefore, the aim of the second part of this study was to investigate the possibility of improving the dissolution rate of progesterone/β-CD binary systems upon formation of ternary complexes with the hydrophilic polymer, PEG 6000, as β-CD had the smallest progesterone solubility and dissolution capacity among the four cyclodextrins studied (β‐CD, HPβ-CD, HPγ-CD and PMβ-CD). The results indicated that dissolution constant rates were considerably enhanced for the 5% and 10% progesterone/β-CD complexes in PEG 6000. The interaction of progesterone with the cyclodextrins of interest on the form of the binary physical mixtures, complexes, or ternary complexes were investigated by differential scanning calorimetry (DSC) and Fourier transformed-infrared spectroscopy (FT-IR). The results proved that progesterone was diffused into the cyclodextrin cavity, replacing the water molecules and, in case of ternary systems, that the progesterone β-cyclodextrin was well dispersed into PEG, thus improving progesterone bioavailability for subsequent oral delivery in the same way as derivatized cyclodextrins. The present work proves that ternary complexes are promising systems for drug encapsulation.

Effect of iontophoresis and penetration enhancers on transdermal absorption of metopimazine

BACKGROUND Metopimazine is an antiemetic drug already used by oral and rectal administration. It would be interesting to develop a new formulation for a transdermal administration. OBJECTIVE The objective of this study was to determine the influence of iontophoresis on the metopimazine transdermal absorption and the possible synergistic enhancement with chemical enhancers. METHODS Transdermal transport of metopimazine was studied in vitro in a Franz cell with pig skin according to the following protocol: 1h of iontophoresis followed by 7h of passive diffusion. Different current densities were applied: 0, 0.125, 0.25 and 0.5 mA/cm(2). Chemical enhancers used as solvent dilution were ethanol, propylene glycol and isopropyl myristate. Metopimazine was assayed by HPLC. Fourier transform infrared spectroscopy was used to determinate the interaction between chemical enhancers and stratum corneum. RESULTS The iontophoresis has increased the percutaneous absorption of metopimazine and has decreased the lag time with 3.85+/-0.90 microg/(cm(2)h) and 1.9h for 0.5 mA/cm(2) and with 0.27+/-0.20 microg/(cm(2)h) and >8h for passive diffusion. Transdermal transport has been increased with current density and with isopropyl myristate and was not modified by ethanol or propylene glycol. CONCLUSION Results indicated that iontophoresis is an effective method for transdermal administration of metopimazine.

Cross-linking of hard gelatin carbamazepine capsules: effect of dissolution conditions on in vitro drug release

The aim of this study was to determine if the use of both enzyme and surfactant in the dissolution medium changes the in vitro drug release from cross-linked hard gelatin capsules containing a water-insoluble drug. Hard gelatin capsules were cross-linked by a controlled exposure to formaldehyde resulting in different stressed capsules and carbamazepine (CBZ) was chosen as a drug model. In vitro dissolution studies were conducted using simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) with enzymes. Sodium lauryl sulfate (SLS) was added in the dissolution medium at a concentration of 2% m/v both in SGF and SIF with pepsin and pancreatin, respectively. The percentage of CBZ dissolved was reduced by increasing the degree of gelatin cross-linking. For unstressed hard gelatin capsules, 36% of the CBZ was released after 1 h, lowering to 5% for highly stressed hard gelatin capsules in the SGF. A similar effect was observed with SIF. In the case of moderately stressed hard gelatin capsules, addition of enzyme in the dissolution medium enhanced the percentage of CBZ dissolved. The dissolution level increased from 12% to 39% in SGF with pepsin for hard gelatin capsules cross-linked with 1500 ppm formaldehyde. On the contrary, the use of enzyme in the dissolution medium did not increase the dissolution of CBZ from highly stressed hard gelatin capsules. Surprisingly, the addition of SLS in the medium did not allow the release of the CBZ both in SGF and in SIF. The results of this study demonstrate that the use of enzyme in the dissolution medium is justified for moderately cross-linked hard gelatin capsules. However, the action of a surfactant added in the medium containing enzyme remains unclear.

Soluble epoxide hydrolase inhibition prevents coronary endothelial dysfunction in mice with renovascular hypertension.

Objectives The study addresses the hypothesis that endothelial dysfunction in experimental arterial hypertension can be related to an alteration in epoxyeicosatrienoic acids (EETs) pathway and can be prevented by the inhibition of EETs degradation by soluble epoxide hydrolase (sEH). Methods and results Arterial hypertension was induced in FVB/N mice by renal artery stenosis (‘two-kidney–one-clip’, 2K1C). Seven weeks after surgery, increased aortic pressures (Millar tonometer; Millar Instruments, Houston, Texas, USA) and cardiac hypertrophy (echocardiography) were present in 2K1C mice as compared with control mice. Left coronary artery endothelium-dependent relaxations to acetylcholine were decreased in 2K1C mice without modification in the relaxing responses to NS309 and NS1619, the openers of calcium-activated potassium channels mediating the hyperpolarizing effect of EETs. The inhibitors of the EET-synthesizing enzymes cytochrome P450 epoxygenases, fluconazole and N-methylsulfonyl-6-(2-propargyloxyphenyl)-hexanamide (MSPPOH), reduced the coronary relaxations to acetylcholine in control but not in 2K1C mice. The sEH expression was increased in 2K1C mice. The sEH inhibitor 12-(3-adamantan-1-yl-ureido)dodecanoic acid administered for 2 weeks starting 5 weeks after surgery in 2K1C mice (25 mg/l in drinking water) reduced aortic pressures and cardiac hypertrophy, improved the coronary relaxations to acetylcholine and restored the inhibitory effect of fluconazole and MSPPOH on acetylcholine-induced relaxations, without modifying the relaxations to NS309 and NS1619. Conclusion These results demonstrate that a reduced EET-mediated relaxations related to an increased degradation by sEH contributes to coronary endothelial dysfunction in 2K1C hypertensive mice. Inhibiting sEH prevents endothelial dysfunction by restoring EET-mediated relaxations and thus, could represent a promising pharmacological intervention to limit cardiovascular morbidity and mortality in arterial hypertension.

Design of Nanocapsules Based on Novel Fluorophilic Cyclodextrin Derivatives and Their Potential Role in Oxygen Delivery

The authors report an amphiphilic and fluorophilic β-cyclodextrinderivative synthesized (perfluoro-β-cyclodextrins: β-CD-C8F)according to a patent registered by Skiba et al. A new type of nanocapsule(PFC-NC) based on perfluoro-β-cyclodextrins was prepared in a single step bycolloidal nanoprecipitation. PFC-NC is fluorophilic carrier that could potentially be used invarious types of pharmaceutical posology. Their potential as controlled releaseoxygen delivery systems was evaluated. PFC-NC were spherical and homogeneous particles with mean diameter of 335 nm and zeta potential of -73 mV. They were stable for 35 days at 4 and 25 °C. PFC-NC have a prolonged delivery of oxygen with adelayed release as compared to water. The results of this study suggests that highlyfluorinated-cyclodextrin could constitute a promising new component of nanocapsules.Fluorocarbon-in-water nanocapsules also represent a safe and cost-effective vehiclesfor in-vivo oxygen delivery.

Solid Dispersions for Oral Administration: An Overview of the Methods for their Preparation.

Oral drug delivery remains the most physiological and therefore the most preferred, simplest and easiest administration route. Nevertheless, a multitude of potentially clinically important drugs will not reach the market or achieve their full potential unless their oral bioavailability is improved by formulation. The aim of this review is to present an overview of properties, formulation, excipients and characterization of solid dispersions corresponding to one of the different formulation strategies for design and development of poorly soluble drugs. This work will review and compare in detail the evolution of solid dispersions focused on the different methods of formulation and production of solid dispersions, their stability, their release properties, their pharmacokinetics and methods for their physicochemical characterization.

2-Hydroxypropyl β-Cyclodextrin: A New Tool for the Improvement of Chemical Stability of Tiagabine HCl

The aim of this paper was to describe the use of a 2-hydroxypropyl beta-cyclodextrin (2-HPCD) as a tool to improve the chemical stability of tiagabine hydrochloride (TGB). HPLC method was used to quantify TGB. The correla- tion coefficient of the linearity (r 2 ) of HPLC method was more than 0.999 whilst the limit of detection and the limit of quantification of TGB were 0.6494 � g ml -1 and 1.765� g ml -1 respectively. The effect of 2-HPCD on the chemical stabil- ity of TGB was compared with � -tocopherol and ascorbic acid, the most recognized antioxidants used to enhance the sta- bility of TGB. The stability was expressed by (% w/w) of the total related substances (TRS) of TGB. When TGB was ex- posed for 24 h to 50°C, the TRS were 3.264% (SD ±0.077) and 3.125% (SD ±0.053) in the presence of � -tocopherol and ascorbic acid, respectively. The TRS of TGB complexed with 2-HPCD was 2.142% (SD ±0.045). This study demon- strates that 2-HPCD exhibits an obvious enhancement of TGB chemical stability with a different mechanism compared with the usual antioxidants.

What structural information can ion trap mass spectrometry bring for the characterization of permethylated cyclodextrins

Cyclodextrins (CDs) are cyclic oligosaccharides composed of six, seven and eight a-1,4-linked D-glucopyranose units for the a-, band g-CD, respectively. These macrocyclic molecules have a truncated cone-shaped structure whose hydrophobic cavity enables the formation of inclusion complexes thus allowing various pharmaceutical applications. Indeed, CDs and derivatives are commonly used as drug excipients to improve drug solubility, bioavailability and stability. Permethylated CDs usually comprise a large number of positional and regional isomers. Therefore, it is essential to characterize their structures by determining their substitution patterns and their degree of substitution (DS: i.e. the number of methyl groups per glucopyranose unit). Direct injection mass spectrometry is known to be an easy and fast method to achieve CD characterization. In fact, quadrupole mass spectrometry with electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) has been used to determine the DS for DiMe-b-CD, Me-b-CD, and sulfobutylether-CD. Ion trap mass spectrometry (ITMS), has, however, been rarely described in the literature for this purpose. Ion trap mass spectrometry is based on the trapping of ions in a symmetrical three-dimensional electric radiofrequency field under appropriate conditions. The quantity of ions in the trap and the depth of the potential well need to be optimized as they greatly influence the quality and reliability of the data. The quantity of ions in the trap is controlled by the ion current control (ICC). When the trap is overloaded, space charge effects impair the quality of mass spectra as the signal intensity is reduced. For quantitative experiments, the linearity deviates at high concentration thus reducing the dynamic range. Furthermore, ions with identical m/z value interfere with each other to a much greater extent than ions of different m/z values because they move on similar ion trajectories. The other parameter which needs to be adjusted is the target mass, a parameter given by the instrument supplier whose values will optimize different voltages for ion transmission and the depth of the pseudo-potential well. The ions with masses close to the value of the target mass will be the best trapped. Here we describe our experiments using ESI-ITMS to characterize permethylated b-CDs. The parameters that we needed to optimize on the ion trap mass spectrometer are described and the structural information provided by MS experiments is more particularly discussed. The Me-b-CD Cavasol W7 M Pharma was obtained from Wacker Chemie AG (Burghausen, Germany). Its DS is in the range 1.7–1.9. The other permethylated b-cyclodextrin (PMCD) was synthesized in the Laboratoire de Pharmacie Galénique (Rouen, France). HPLC grade acetonitrile (MeCN), methanol (MeOH), and ammonium acetate were supplied by VWR (Fontenaysous-Bois, France). Deionized water (18 MV) was obtained from a Waters Milli-Q apparatus (Waters, SaintQuentin-Yvelines, France). For ESI-MS analysis, CD samples were prepared in water and then diluted in MeOH/ H2O (50:50, v/v) or MeCN/ H2O (50:50, v/v) to a concentration of 1 ngmL . In some cases, 5mL of terscience.wiley.com) DOI: 10.1002/rcm.3535 NaCl (1 mg mL ) were added to 500mL of the CD solutions. ESI mass spectra were recorded on an Esquire–LC ion trap mass spectrometer equipped with an ESI source and the Esquire control 6.16 data system (Bruker Daltonics, Wissembourg, France). The ESI parameters were: capillary voltage 4 kV, end plate volatage 3.5 kV and skimmer voltage 62 V. Nitrogen was used as the drying (flow rate of 5 L min , 3008C) and nebulizing (7psi pressure) gas. The samples were flow injected at 3mL min 1 by means of a syringe pump (ColePalmer, Vernon Hills, IL, USA). Positive ions were detected using the standard scan at normal mass resolution: the scan speed was 13000 m/z units s 1 and the mass resolution was 0.6m/z units at half peak height (FWHM) over a range m/z 50–2200. Helium was the buffer gas and the pressure in the ion trap was 1.2 10 5 mbar. The values of spectra averages and rolling average were 10 and 5, respectively. For all the target mass values tested, the corresponding values of cone voltage (voltage differential between the capillary exit and the skimmer) and trap drive (depth and shape of the pseudo potential well) are listed in Table 1. For MS experiments, each precursor ion was selected with an isolation width of 2m/z units and was excited by a voltage of between 1.2 and 1.3 V. The low mass cut-off value (LCMO) was set at 28% of the precursor ion m/z value. When experiments are performed in water, CDs are mainly detected as MNaþ species but adducts with Kþ and NH4 are also observed. To enhance the formation of these adducts, NaCl or NH4CH3CO2 is usually added. Ammonium salts are often preferred in ESI-MS because they are more volatile. The spectra obtained here,