Inclusion complex of colchicine in hydroxypropyl-β-cyclodextrin tenders better solubility and improved pharmacokinetics

Context: Colchicine (CLC) causes cell death by destabilizing the tubulin unit. However, it ionizes at physiological pH resultant low bioavailability and therapeutic efficacy.

Objectives: We have attempted to augment the bioavailability of CLC by fabricating the inclusion complex with hydroxypropyl-β-cyclodextrin (HP-β-CD).

Materials and methods: CLC-HP-β-CD inclusion complex was prepared and evaluated with Fourier-transform infrared spectroscopy, differential scanning calorimetry, powder X-ray diffractometry, scanning electron microscopy, ¹H nuclear magnetic resonance (¹H NMR) spectroscopy and rotating frame overhauser enhancement spectroscopy (ROESY). Oral bioavailability of CLC-HP-β-CD inclusion complex was analyzed using high performance liquid chromatography method.

Results and discussion: Our phase-solubility data indicated the formation of a stable complex with K_c ~0.31?mM^?1 at pH 7.4. ¹H NMR ascertains that NHCOCH₃ moiety of CLC enters in the HP-β-CD cavity and deshielded the H-3 and H-5 protons. ROESY also correlates the H_f and H_g of CLC with H-3 and H-5 protons of HP-β-CD and indicates that H_f and H_g protons of CLC are present either as cis and/or trans form in CLC-HP-β-CD inclusion complex. Pharmacokinetic studies showed a 1.82-fold increase in absolute bioavailability of CLC upon complexation.

Conclusion: CLC-HP-β-CD inclusion complex may potentially be used as a viable formulation of CLC.     

Nanosizing of valsartan by high pressure homogenization to produce dissolution enhanced nanosuspension: pharmacokinetics and pharmacodyanamic study

Purpose: The purpose of the present study was to formulate and evaluate nanosuspension of Valsartan (VAL), a poorly water soluble and low bioavailable drug (solubility of 0.18?mg?mL^?1; 23% of oral bioavailability) with the aim of improving the aqueous solubility thus the bioavailability and consequently better anti-hypertensive activity.

Methods: Valsartan nanosuspension (VAL-NS) was prepared using high-pressure homogenization followed by lyophilisation. The screening of homogenization factors influencing nanosuspension was done by 3-factorial, 3-level Box-Behnken statistical design. Model suggested the influential role of homogenization pressure and cycles on drug nanosizing. The optimized formulation containing Poloxamer^?188 (PXM 188) was homogenized for 2 cycles at 500 and 1000?bar, followed by 5 cycles at 1500 bars.

Results: The size analysis and transmission electron microscopy showed nanometric size range and uniform shape of the nanosuspension. The in vitro dissolution showed an enhanced release of VAL from nanosuspension (VAL-NS) compared to physical mixture with PXM 188. Pharmacodynamic results showed that, oral administration of VAL-NS significantly lowered (p?≤?0.001) blood pressure in comparison to non-homogenized VAL (VAL-Susp) in Wistar rat. The level of VAL in rat plasma treated with VAL-NS showed significant difference (p?≤?0.005) in C_max (1627.47?±?112.05?ng?mL^?1), T_max (2.00?h) and AUC_0→24 (13279.2?±?589.426?ng?h?mL^?1) compared to VAL-Susp that was found to be 1384.73?±?98.76?ng?mL^?1, 3.00?h and 9416.24?±?218.48?ng?h?mL^?1 respectively. The lower T_max value, proved the enhanced dissolution rate of VAL.

Conclusion: The overall results proved that newly developed VAL-NS increased the plasma bioavailability and pharmacodyanamic potential over the reference formulation containing crude VAL.     

Preparation,characterization and pharmacokinetic studies of linalool-loaded nanostructured lipid carriers

Context Linalool (LL) is associated with numerous pharmacological activities. However, its poor solubility usually results in poor bioavailability, and further limited its applications.

Objective To reduce volatilization and improve bioavailability of LL, linalool-loaded nanostructured lipid carriers (LL-NLCs) were prepared.

Materials and methods LL-NLCs were prepared using high-pressure homogenization method and optimized via response surface methodology-central composite design, followed by characterization, including particle size (PS), zeta potential (ZP), transmission electron microscope (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and in vitro release study. Rats were administered 300?mg?×?kg?^??¹ LL with each preparation (LL-NLCs or LL) via oral gavage.

Results LL-NLCs had a PS of 52.72?nm with polydispersity index of 0.172, and ZP of –16.0?mV. The encapsulation efficiency and drug loading gave 79.563 and 7.555%, respectively. The cumulative release of LL from free LL reached 51.414% at 180?min, while LL from LL-NLCs was 15.564%. All the pharmacokinetics parameters of LL-NLCs were better than those of LL, including C_max (from 1915.45 to 2182.45?ng?×?mL?^??¹), AUC_0–t (from 76003.40 to 298948.46?ng?×?min?×?mL?^??¹) and relative bioavailability (393.34%). The t_1/2, MRT and t_max of LL-NLCs (110.50, 146.66 and 60?min) were also longer than that of LL (44.72, 45.66 and 40?min).

Discussion and conclusion LL-NLCs were for the first time prepared and its oral administration in rats thoroughly investigated. LL-NLCs exhibited sustained release effect and increased absorption of LL. Therefore, these findings might provide a potential possibility for clinical application of LL.     

Improvement of tetracaine antinociceptive effect by inclusion in cyclodextrins

Local anesthetics (LA) are among the most important pharmacological compounds used to attenuate or eliminate pain. However, systemic toxicity is still a limitation for LA application, especially for ester-type drugs, such as tetracaine (TTC) that presents poor chemical stability (due to hydrolysis by plasma esterases). Several approaches have been used to improve LA pharmaceutical properties, including the employment of drug-delivery systems. Here we used beta-cyclodextrin (β-CD) or hydroxypropyl-beta-cyclodextrin (HP-β-CD) to develop two new TTC formulations (TTC:β-CD and TTC:HP-β-CD). The inclusion complexes formation, in a 1:1 stoichiometry, was confirmed by differential scanning calorimetry, X-ray diffraction, UV-VIS absorption and fluorescence. Nuclear magnetic resonance (DOSY experiments) revealed that TTC association with HP-β-CD is stronger (K_a?=?1200?mol/L^?1) than with β-CD (K_a?=?845?mol/L^?1). Moreover, nuclear Overhauser effect (NOE) experiments provided information on the topology of the complexes, where TTC aromatic ring is buried inside the CD hydrophobic cavity. In vitro tests with 3T3 fibroblast cells culture revealed that complexation decreased TTC cytotoxicity. In addition, the total analgesic effect of TTC, tested in rats through the infraorbital nerve test, was improved in 36% with TTC:β-CD and TTC:HP-β-CD. In conclusion, these formulations presented potential for future clinical use, by reducing the toxicity and increasing the antinociceptive effect of tetracaine.     

Preparation,characterization, dissolution,and permeation of flibanserin − 2-HP-β-cyclodextrin inclusion complexes

Flibanserin (FLB), an antiserotonin drug, is used to treat women with hypoactive sexual appetite disorder. FLB shows low bioavailability (~33%) probably due to its low water solubility. The current study investigated the impact of hydroxypropyl-β-cyclodextrin (HP-β-CD) and sodium lauryl sulfate (SLS) on the dissolution and permeation of FLB. HP-β-CD–FLB inclusion complexes were prepared using physical mixing and kneading at 1:1 and 1:2 M ratios and characterized using differential scanning calorimetry, Fourier transform infrared spectroscopy, and powder X-ray diffractometry. The dissolution and permeation of the complexes through a cellophane membrane were performed in, 0.1, 0.3 and 0.5% SLS in phosphate buffer (pH 6.8).Derived from the slope of the linear phase solubility diagram, the apparent stability constant (K_1:1) was 372.54 M⁻¹. Kneading changed the crystalline form of FLB to an amorphous appearance characterized by minimal crystalline peaks, indicating successful inclusion complex formation. In addition, the HP-β-CD–FLB inclusion complexes showed twofold increased dissolution efficiency at 6 h. The cumulative FLB amount permeated at 6 h increased from 14.1% to 21.88% and 34.56% in the presence of 0.1% and 0.3% of SLS, respectively. However, increasing SLS to 0.5% did not show an increase in FLB permeation. Therefore, the HP-β-CD–FLB inclusion complex has an improved dissolution rate compared to FLB alone. The presence of SLS in the dissolution medium increases the dissolution rate of pure FLB and its complex with HP-β-CD. kneaded 1:1 complex was formulated bioadhesive buccal tablets and showed enhanced drug release.     

Bivalent sequential binding of docetaxel to methyl-β-cyclodextrin

New docetaxel (Dtx) and cyclodextrin (CD) inclusion complexes having improved apparent water solubility (up to 9.98 mg mL⁻¹) were obtained from phase solubility diagrams. γ-CD and SBE-β-CD offered only poor solubility enhancements while considerable increases in apparent solubility were obtained with Me-β-CD (20%, w/w) and HP-β-CD (40%, w/w) (9.98 mg mL⁻¹ and 7.43 mg mL⁻¹, respectively). The complexation mechanism between Dtx and Me-β-CD was investigated by circular dichroism spectrometry, two-dimensional ¹H NMR (NOESY) in D₂O, isothermal titration calorimetry (ITC) and molecular docking calculations. Circular dichroism and NOESY confirmed the existence of non-covalent interactions between Dtx and Me-β-CD and suggested that the tert-butyl group (C₆-C₉) and two aromatic groups (C₂₄-C₂₉ and C₃₀-C₃₅) of Dtx interacted with the Me-β-CD molecules. The combination of ITC results to molecular docking calculations led to the identification of an unconventional sequential binding mechanism between Me-β-CD and Dtx. In this sequential binding, a Me-β-CD molecule first interacted with both tert-butyl and C₃₀-C₃₅ aromatic groups (K₁: 744 M⁻¹). Then a second Me-β-CD molecule interacted with the C₂₄-C₂₉ aromatic group (K₂: 202 M⁻¹). The entropy of the first interaction was positive, whereas a negative value of entropy was found for the second interaction. The opposite behavior observed for these two sites was explained by differences in the hydrophobic contact surface and functional group flexibility.     

The effect of complexation with cyclodextrins on the antioxidant and antimicrobial activity of ellagic acid

Purpose: The aim of the paper was to develop the simple procedures for preparation of inclusion complexes of ellagic acid (EA) with cyclodextrins (CDs) and to investigate their antioxidant and antimicrobial activity.

Methods: The structural characterization was carried out using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and nuclear magnetic resonance (NMR) methods. The phase solubility technique was used to investigate the interactions between ‘host’ and ‘guest’ molecules and to estimate the molar ratio between them. The antioxidant and antimicrobial activity of EA and inclusion complexes were determined.

Results: The apparent stability constants were found to be 117?dm³ mol^?1 for the complex with β-CD and 161?dm³ mol^?1 for the complex with (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD). The results of phase-solubility studies showed that EA formed the inclusion complexes with CDs in the molar ratio of 1:1. The calculated half-maximal inhibitory concentration was 41.18?μg cm^?3 for butyl hydroxy toluene, 1.96?μg cm^?3 for EA, 0.88?μg cm^?3 for inclusion complex with HP-β-CD, and 1.27?μg cm^?3 for inclusion complex with β-CD.

Conclusion: The stability constants indicated the rapid release of EA from the inclusion complexes in the aqueous medium at 25?°C. The antioxidant activity of EA was increased, while the antimicrobial activity was preserved after complexation with CDs.     

Hyperbranched dendritic nano-carriers for topical delivery of dithranol

Abstract

The purpose of the current investigation was to explore the potential of polypropylene imine (PPI) dendrimers to deliver dithranol (DIT) topically and to evaluate its encapsulation, permeation and skin irritation potential. PPI (5.0 generation, 5.0?G) dendrimers and DIT-loaded PPI (DIT–PPI) were prepared and characterized by spectroscopy and transmission electron microscopy. DIT encapsulation, in vitro skin permeation study, skin irritation studies, fluorescent studies and tape stripping studies were performed. Loading of DIT was found to be pH dependent with maximum encapsulation at acidic pH (1.0?±?0.02, 17.2?±?0.56 and 57.1?±?1.32% at 7.4, 5.5 and 1.2 pH, respectively). DIT–PPI showed significantly enhanced permeation rate constant and lesser skin irritation (11.61?±?1.80?μg/cm²/h and 1.0, respectively) when compared with the plain DIT solution (2.72?±?0.31?μg/cm²/h and 2.3, respectively). Skin separation studies and confocal laser scanning microscope images showed that the dye-loaded dendrimers exhibits deposition of dye in pilosebaceous compartment. These studies demonstrate that PPI can be exploited to improve the topical bioavailability of the molecules in a controlled pattern. The enhanced accumulation of DIT via dendrimer carrier within the skin might help optimize targeting of this drug to the epidermal and dermal sites, thus creating new opportunities for well-controlled, modern topical application of DIT for the treatment of psoriasis.     

Biological activities of ethyl acetate extract of different parts of Hyssopus angustifolius

Context: Hyssopus angustifolius M. Bieb. (Lamiaceae) is one of the most important medicinal plants in Iranian traditional medicine for the treatment of lung inflammation, laryngitis and cough relief. Much attention has been paid to this medicinal plant because of its traditional uses.

Objective: The present study examined the antioxidant and antihemolytic activities of ethyl acetate extract of stems, leaf and flowers of Hyssopus angustifolius.

Materials and methods: Antioxidant activity of extracts was evaluated by employing six different models, i.e., DPPH, nitric oxide and hydrogen peroxide scavenging, metal chelating and reducing power activities and hemoglobin-induced linoleic acid system. Also, antihemolytic activity was evaluated against hydrogen peroxide-induced hemolysis.

Results: Flowers extract showed the better activity than leaf and stems extracts in DPPH radical scavenging activity (IC₅₀ was 275.4?±?7.6 μg mL^?1). Leaf, stems and flowers extracts showed good nitric oxide scavenging activity (IC₅₀ were 376.6?±?11.4 µg mL^?1 for flowers, 297.6?±?9.6 μg mL^?1 µg mL^?1 for leaves and 837.8?±?19.2 µg mL^?1 for stems). The leaf extract exhibited better hydrogen peroxide scavenging and Fe²⁺ chelating activity than stems and flowers extracts. In hemoglobin-induced linoleic acid system, all of the extracts exhibited very good activity. Also, extracts show weak reducing power activity. The ethyl acetate extract of leaf showed better antihemolytic activity than the flower and stems (IC₅₀ was 94.0?±?2.4 μg mL^?1).

Discussion and conclusion: These findings give a scientific basis to the traditional usage of Hyssopus angustifolius, also showing its potential as rich sources of natural antioxidant compounds.     

The essential oils chemical compositions and antimicrobial,antioxidant activities and toxicity of three Hyptis species

Abstract

Context: Hyptis suaveolens (Linn.) Poit., Hyptis rhomboidea Mart. et Gal., and Hyptis brevipes Poit., are three species of Hyptis Jacq. (Lamiaceae). Hyptis suaveolens is used for the treatment of fever, headache, gastrointestinal bloating and rheumatism in the traditional folk medicine; Hyptis rhomboidea for hepatitis, ulcer and swollen poison; and Hyptis brevipes for asthma and malaria.

Objective: To characterize chemical compositions of the oils from three Hyptis species and evaluate their potential antimicrobial, radical scavenging activities and toxicities against brine shrimp.

Materials and methods: The oils were obtained by hydrodistillation, and their chemical compositions were investigated by gas chromatography-mass spectrometry (GC-MS). Minimum inhibitory concentrations (MICs) were determined using the tube double-dilution technique. The antioxidant activities were investigated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and toxicities by the brine shrimp bioassay.

Results: Forty-seven, 33 and 28 constituents of oils isolated, respectively, from H. suaveolens, H. rhomboidea and H. brevipes were identified. Among the essential oils, the strongest antioxidant activity was exhibited by H. brevipes with an SC₅₀ value of 2.019?±?0.25?μg?mL^?1. The H. brevipes oil exhibited the strongest antimicrobial activity (3.125–6.25?μg?mL^?1) on pathogens employed in the assay. They all showed significant toxicities with median lethal concentration (LC₅₀) values of 62.2?±?3.07?μg?mL^?1, 65.9?±?6.55?μg?mL^?1 and 60.8?±?9.04?μg?mL^?1, respectively.

Discussion and conclusions: The three Hyptis species oils possess strong antimicrobial activities and toxicities. Hyptis rhomboidea and H. brevipes showed considerable antioxidant activity compared to the positive control.     

Bioavailability of caffeic acid in rats and its absorption properties in the Caco-2 cell model

Context: Caffeic acid (CA) is widely distributed in edible plants, and it is beneficial to human health by exerting various biological effects. The potential pharmacological activities of CA are dependent on its absorption in the gastrointestinal tract.

Objective: To investigate the bioavailability of CA in rats and its absorption properties in the Caco-2 cell model.

Materials and methods: A sensitive LC-MS/MS method was successfully applied to determine CA in rat plasma, perfusate, and Hank's balanced salt solution (HBSS). The absolute bioavailability (F_abs) of CA was obtained after i.v. (2?mg/kg) or i.g. administration (10?mg/kg) to rats. Blood samples (approximately 250?µL) were collected from the jugular vein catheter. Pharmacokinetic parameters were calculated using the 3P97 software (version 2.0 PK software; Chinese Society of Mathematical Pharmacology, Anhui, China). The intestinal absorption of CA was explored by the in situ vascularly perfused rat intestinal preparation. CA (5?mg/kg) was administered into the duodenum. Samples (250?µL) were collected from reservoir at specific times, and the same volume fresh perfusate was replaced. The Caco-2 cell model was applied to measure the permeability of CA from the apical to basolateral side (A?→?B) and from the basolateral to apical side (B?→?A).

Results: The absolute bioavailability (F_abs) of CA was 14.7%, and its intestinal absorption was 12.4%. The P_{app A→B} values of CA were ranging from (4.87?±?1.72)?×?10^?7?cm/s to (5.05?±?0.66)?×?10^?7?cm/s as the concentration varied from 5 to 15?µg/mL.

Conclusion: CA was shown to have low oral bioavailability in rats, low intestinal absorption, and poor permeability across Caco-2 cells.     

The effect of acute exposure to coarse particulate matter air pollution in a rural location on circulating endothelial progenitor cells: results from a randomized controlled study

Abstract

Context: Fine particulate matter (PM) air pollution has been associated with alterations in circulating endothelial progenitor cell (EPC) levels, which may be one mechanism whereby exposures promote cardiovascular diseases. However, the impact of coarse PM on EPCs is unknown.

Objective: We aimed to determine the effect of acute exposure to coarse concentrated ambient particles (CAP) on circulating EPC levels.

Methods: Thirty-two adults (25.9?±?6.6 years) were exposed to coarse CAP (76.2?±?51.5?μg?m^?3) in a rural location and filtered air (FA) for 2 h in a randomized double-blind crossover study. Peripheral venous blood was collected 2 and 20 h post-exposures for circulating EPC (n?=?21), white blood cell (n?=?24) and vascular endothelial growth factor (VEGF) (n?=?16–19) levels. The changes between exposures were compared by matched Wilcoxon signed-rank tests.

Results: Circulating EPC levels were elevated 2 [108.29 (6.24–249.71) EPC?mL^?1; median (25th–75th percentiles), p?=?0.052] and 20 h [106.86 (52.91–278.35) EPC?mL^?1, p?=?0.008] post-CAP exposure compared to the same time points following FA [38.47 (0.00–84.83) and 50.16 (0.00–104.79) EPC?mL^?1]. VEGF and white blood cell (WBC) levels did not differ between exposures.

Conclusions: Brief inhalation of coarse PM from a rural location elicited an increase in EPCs that persisted for at least 20 h. The underlying mechanism responsible may reflect a systemic reaction to an acute “endothelial injury” and/or a circulating EPC response to sympathetic nervous system activation.     

Development of orally disintegrating tablets of Perphenazine/hydroxypropyl-β-cyclodextrin inclusion complex

The aim of the present work was to prepare perphenazine (PPZ) orally disintegrating tablets (ODTs) based on the use of hydroxypropyl-β-cyclodextrin (HP-β-CD) forming inclusion complex with PPZ to improve the solubility and dissolution of this practically insoluble drug. Phase solubility studies were performed to evaluate the complexation of PPZ with HP-β-CD in three aqueous systems. The inclusion complex prepared by evaporation method was characterized by different physicochemical techniques, including the dissolution studies. The prepared complex was incorporated into ODTs containing different fillers and disintegrants. The ODTs prepared by direct compression were evaluated for drug content, hardness, porosity, friability, in vitro disintegration time (DT), wetting time (WT) and dissolution profiles. The solubility and dissolution rate were substantially improved compared with that of PPZ. Differential scanning calorimetry (DSC), X-ray powder diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) analyses suggested that PPZ could form true inclusion complex with HP-β-CD. The optimized formulation F6 exhibited short DT (15.5 ± 1.9 s) and WT (34.2 ± 2.3 s), sufficient hardness (30.4 ± 1.6 N/mm) and rapid drug dissolution. The developed tablet formulation could be a promising drug delivery system with improvements in PPZ bioavailability and patient compliance.     

Comparison of the Complexation between Methylprednisolone and Different Cyclodextrins in Solution by 1H-NMR and Molecular Modeling Studies

Complexation in solution between methylprednisolone and three different cyclodextrins [2-hydroxypropyl-β-cyclodextrin (HP-β-CD), γ-cyclodextrin (γ-CD), and 2-hydroxypropyl-g-cyclodextrin (HP-γ-CD)] was studied using phase solubility analysis, one and two-dimensional ¹H-NMR and molecular modeling. Estimates of the complex formation constant (K_1:1) show that the tendency of methylprednisolone to complex with CDs follows the order: γ-CD > HP-γ-CD > HP-β-CD. The large variation of chemical shifts from protons located around the interior of the hydrophobic cavity (H-3′, H-5′, and H-6′) coupled with minimal variation of shifts from protons located on the outer sphere of γ-CD (H-1′, H-2′, and H-4′) provided clear evidence of inclusion complexation. The molecular modeling study, indicated inclusion complexation between methylprednisolone and γ-CD and HP-γ-CD by entrance of the A and B rings of methylprednisolone into the CD cavity from its bigger rim. For the methylprednisolone: HP-β-CD complex, the molecular modeling study could not be carried out; hence, two possibilities of complex formation are proposed: (1) methylprednisolone enters HP-β-CD from the wider rim by its D and C ring, (2) the A and B ring of methylprednisolone enters deeper in to the CD cavity so that a part of the A ring of steroidal structure is outside of the cavity. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:3863–3873, 2010     

The effects of verapamil on the pharmacokinetics of curculigoside in rats

Context: Clarifying the potential mechanism of the poor oral bioavailability of curculigoside would be helpful for for investigating pharmacological effects and clinical applications.

Objective: To clarify the main mechanism for poor oral bioavailability.

Materials and methods: First, the pharmacokinetics of curculigoside (20?mg/kg) in rats with and without pretreatment with verapamil (10?mg/kg) was determined using a sensitive and reliable LC-MS method. Then the effects of verapamil on the transport and metabolic stability of curculigoside were investigated using Caco-2 cell transwell model and rat liver microsome incubation systems.

Results: The results showed that verapamil could significantly increase the peak plasma concentration (from 60.17?ng/mL to 93.66?ng/mL) and AUC_0?t (from 289.57 to 764.02?ng·h/mL) of curculigoside. The Caco-2 cell experiments indicated that the efflux ratio of curculigoside was 3.92 (P_appAB 6.43?±?0.57?×?10?^?7?cm/s; P_appBA 2.52?±?0.37?×?10?^?36?cm/s), P-gp might be involved in the transport of curculigoside, and verapamil could inhibit the efflux of curculigoside and increase the absorption of curculigoside significantly in the Caco-2 cell monolayer. Additionally, the rat liver microsome incubation experiments indicated that verapamil could significantly decrease the intrinsic clearance rate of curculigoside (from 38.8 to 23.6?μL/min/mg protein).

Discussion and conclusion: These results indicated that verapamil could significantly change the pharmacokinetic profiles of curculigoside in rats, the poor absorption due to P-gp mediated efflux in intestine and high intrinsic clearance rate in rat liver may be the main reason for the poor oral absolute bioavailability of curculigoside.     

Simultaneous determination of synephrine,arecoline, and norisoboldine in Chinese patent medicine Si-Mo-Tang oral liquid preparation by strong cation exchange high performance liquid chromatography

Context: Chinese patent medicine Si-Mo-Tang oral liquid preparation (SMT) is composed of Aucklandia luppa Decne (Compositae), Citrus aurantium Linn (Rutaceae), Lindera aggregata (Sims) Kosterm (Lauraceae), and Areca catechu Linn (Arecaceae). Studies of SMT have been impeded due to the lack of quality control methods.

Objective: This study aimed to simultaneously determine three alkaloids including synephrine, arecoline, and norisoboldine in SMT for the first time.

Materials and methods: A strong cation exchange (SCX) high performance liquid chromatography (HPLC) method was developed to simultaneously determine synephrine, arecoline, and norisoboldine in SMT, and was compared with ion-pairing chromatography using regular reversed-phase chromatography columns. System suitability parameters of synephrine, arecoline, and norisoboldine using the SCX chromatography column were investigated.

Results: Results demonstrated that good separations were achieved on an Agilent SCX (250?×?4.6?mm, 5 µm) column at 35°C. The mobile phase consisting of methanol-0.2% phosphoric acid was delivered at a constant flow of 1.0?mL min^?1 and the eluent was monitored at 215?nm. The HPLC method showed good linearity for the examined concentration ranges of 2.55–255.0, 1.30–208.0, and 2.06–201.6 µg mL^?1 for synephrine, arecoline, and norisoboldine, respectively. The limits of quantification (S/N?=?10) were 2.55, 1.30, and 2.06 µg mL^?1, the limits of detection (S/N?=?3) were 1.53, 0.78, and 1.21 µg mL^?1, and average recoveries were 98.99, 95.63 and 99.04%, respectively, for synephrine, arecoline, and norisoboldine.

Discussion and conclusion: This method has been successfully applied to determine synephrine, arecoline, and norisoboldine in Chinese patent medicine SMT.     

Absorption mechanism of oxymatrine in cultured Madin–Darby canine kidney cell monolayers

Context Oxymatrine (OMT) is beneficial to human health by exerting various biological effects. Objective To investigate the absorption mechanism of OMT and discover absorption enhancers using Madin–Darby canine kidney (MDCK) cell monolayers.

Materials and methods Concentration effects on the transport of OMT were measured in the range of 1.0?×?10^?5–1.0?×?10^?3 M in 2?h. Then, the effect of time, direction, temperature and pH on the transport of OMT at 10^?4 M was studied. Moreover, P_app of OMT was determined in the absence/presence of cyclosporine and surfactants at 100?μM to further confirm the relative transport mechanism.

Results The P_{app AP→BL} ranged from (3.040?±?0.23)?×?10^?6 to (3.697?±?0.19)?×?10^?6?cm/s as the concentration varied from 10^?5 to 10^?3 M. OMT showed similar P_app at 4 and 37?°C (p?>?0.05). Increasing the apical pH 7.4 and 8.0 resulted in P_app versus pH 5.0 (p?<?0.01). Furthermore, in the presence of cyclosporine and surfactants including sodium citrate, sodium dodecyl sulphate (SDS) and deoxysodium cholate, P_app was (0.318?±?0.033)?×?10^?5, (0.464?±?0.048)?×?10^?5, (0.897?±?0.115)?×?10^?5 and (1.341?±?0.122)?×?10^?5?cm/s, respectively. In the presence of surfactants, P_app significantly increased up to 1.5–4.3-fold (p?<?0.05).

Discussion and conclusion OMT transport across MDCK cell monolayers was by passive diffusion. Sodium citrate, SDS and deoxysodium cholate serve as excellent absorption enhancers which are useful for the related research improving the oral bioavailability of OMT.     

Influence of mefenamic acid on the intestinal absorption and metabolism of three bioactive flavones in Radix Scutellariae and potential pharmacological impact

Context: Mefenamic acid (MEF) and the dried root of Scutellaria baicalensis Georgi (Radix Scutellariae, RS) share a high possibility of combined medication to treat inflammation.

Objective: The present study investigates the impact of MEF on absorption/disposition of three major components in RS (baicalein, B; wogonin, W; oroxylin A, OA) and further pharmacological changes.

Materials and methods: The apparent permeability (P_app) and percentage of metabolism of B, W and OA at 10?μΜ were measured at the absence/presence of MEF (100?μΜ) in the Caco-2 cell monolayer model. A modified whole blood assay was employed to quantify prostaglandin E₂ (PGE₂) 4, 6 and 8?h post-oral administration with water suspension of MEF at 40?mg/kg and RS at 200?mg/kg.

Results: In the presence of MEF, P_app of B, W and OA were increased from 1.69?±?0.89?×?10^?6, 1.57?±?0.10?×?10^?6 and 3.09?±?0.70?×?10^?6?cm/sec to 5.24?±?0.27?×?10^?6, 6.08?±?0.19?×?10^?6 and 4.13?±?0.38?×?10^?6, whereas their percentage of metabolism was decreased from 72.75?±?2.44%, 73.27?±?3.25% and 89.84?±?2.99% to 21.11?±?0.69%, 17.90?±?5.55% and 45.44?±?3.38%. PGE₂ level was much lower in the co-administration group (49.04?±?2.03?pg/ml) than in the MEF group (73.13?±?3.03?pg/ml) or RS group (494.37?±?11.75?pg/ml) 4?h post MEF dosing, suggesting a synergic effect.

Discussion and conclusion: Co-administration of MEF and RS could induce potential alterations in their pharmacokinetic profiles and anti-inflammatory effects.     

Nanocurcumin: a novel antifilarial agent with DNA topoisomerase II inhibitory activity

Abstract

Objective: The aim of this study is to evaluate the antifilarial, antiwolbachial and DNA topoisomerase II inhibitory activity of nanocurcumin (nano-CUR).

Methods: Nano-CUR formulations (F1–F6) were prepared using free radical polymerization and were characterized by particle size, morphology, encapsulation efficiency and in vitro release kinetics. Antifilarial potential was evaluated in vivo against Brugian filariasis in an experimental rodent model, Mastomys coucha, by selecting the formulation that maximized parasite elimination characteristics. Wolbachial status was determined by PCR and a relaxation assay was used to estimate DNA topoisomerase II inhibitory activity.

Results: Nano-CUR (F3) having a 60?nm diameter and 89.78% entrapment efficiency showed the most favorable characteristics for the elimination of filarial parasites. In vivo pharmacokinetic and organ distribution studies demonstrate significantly greater C_(max) (86.6?±?2.56?ng?ml^?1), AUC_0–∞ (796?±?89.8?ng?d?ml^?1), MRT (19.5?±?7.82 days) and bioavailability of CUR (70.02%) in the organs from which the adult parasites were recovered. The optimized nano-CUR (F3) (5?×?5?mg/kg, orally) significantly augmented the microfilariciadal and adulticidal action of CUR over free CUR (5?×?50?mg/kg, orally) or Diethylcarbamizine (50?mg/kg, orally) against the Brugia malayi Mastomys coucha rodent model. The PCR results showed complete elimination of wolbachia from the recovered female parasites. Interestingly, nano-CUR was also found to be a novel inhibitor of filarial worm DNA topoisomerase II, Setaria Cervi in vitro.

Conclusion: This study recognizes the beforehand antimicrofilarial, antimacrofilarial, anti-wolbachial activity of nano-CUR (F3) over free forms and additionally its strong inhibitory action against the major target filarial parasite enzyme DNA topoisomerase II in vitro.