Absorption-enhancing Effect Research Articles

Study on oral absorption enhancers of Astragalus polysaccharides

Astragalus polysaccharides was lounded to 4-(2-aminoethylphenol), followed by labeling the APS-Tyr with fluorescein-5-isothiocyanate (FITC) at the secondary amino group. The absorption enhancement effects of low molecular weight chitosan and protamine on astragalus polysaccharides were evaluated via Caco-2 cell culture model. The results show that the fluorecent labeling compound has good stability and high sensitivity. On the other hand low molecular weight chitosan and protamine also can promoted absorption of the astragalus polysaccharides without any cytotoxity, and the absorption increase was more significant with increasing the amount of low molecular weight chitosan and protamine. At the same time, the low molecular weight chitosan has slightly better effect. The transepithelial electric resistance (TEER) of Caco-2 cells show that absorption enhancers could improve its membrane transport permeability by opening tight junctions between cells and increasing the cell membrane fluidity.

Effects of Various Penetration Enhancers on Penetration of Aminophylline Through Shed Snake Skin

Cellulite is the accumulation of subcutaneous fat and connective tissue in tights and buttocks. Xanthines, such as aminophylline, are used as phosphodiesterase inhibitors, and are also adenosine receptor antagonists. The aim of the present study was to characterize in vitro aminophylline transdermal absorption through shed snake skin, and to investigate the absorption enhancing effect of various enhancers. Aminophylline gels were prepared using theophylline and ethylenediamine as raw materials of aminophylline, hydroxypropyl methyl cellulose (HPMC) F4M as gelling agent, and propylene glycol as a co-solvent. Sodium tauroglycocholate (STGC) (100, 200, and 500 μg/mL), lauric acid (1.7 and 15%), and ethanol (60%) were added as enhancers. In vitro percutaneous absorption experiments were performed on snake skin using Franz diffusion cells. Flux (J), permeability coefficient (P), and enhancement factor (EF) for each formulation were calculated. The results indicated that all of enhancers significantly enhanced drug permeability. This effect was decreased by increasing the concentration of STGC; in contrast, by increasing the concentration of lauric acid from 1.7 to 15%, EF was enhanced Although ethanol (60%) and STGC (100 μg/mL) showed the highest EFs, the effect of ethanol on drug permeability appeared with a lag time. According to the findings, type and concentration of penetration enhancers can effect on transdermal permeation of drug.

Effective absorption enhancement in small molecule organic solar cells using trapezoid gratings

We demonstrate that the optical absorption is enhanced in small molecule organic solar cells by using a trapezoid grating structure. The enhanced absorption is mainly attributed to both waveguide modes and surface plasmon modes, which is simulated by using finite-difference time-domain method. The simulated results show that the surface plasmon along the semitransparent metallic Ag anode is excited by introducing the periodical trapezoid gratings, which induce the increase of high intensity field in the donor layer. Meanwhile, the waveguide modes result in a high intensity field in acceptor layer. The increase of field improves the absorption of organic solar cells significantly, which is demonstrated by simulating the electrical properties. The simulated results also show that the short-circuit current is increased by 31% in an optimized device, which is supported by the experimental measurement. Experimental result shows that the power conversion efficiency of the grating sample is increased by 7.7%.

In Situ-Generated Nano-Gold Plasmon-Enhanced Photoelectrochemical Aptasensing Based on Carboxylated Perylene-Functionalized Graphene

A novel in situ-generated nanogold plasmon-enhanced photoelectrochemical aptasensor for Hg(2+) ions was fabricated using a perylene-3,4,9,10-tetracarboxylic acid/graphene (PTCA-GR) heterojunction. The fabricated photoelectrochemical aptasensor was based on thymine-Hg(2+)-thymine coordination chemistry and the plasmonic near-field absorption enhancement effect of the subsequent specific catalytic formation of nanogold. The energetic electrons from the surface plasmons of the nanogold were injected into the LUMO orbit of the organic PTCA semiconductor and then rapidly transferred to the electrode through GR due to the possible Hg(2+)-DNA molecular wires following irradiation with the visible light (λ > 450 nm) and at a bias voltage of 0.2 V. The fabricated aptasensor was linear in its response to the concentration of Hg(2+) ions in the range of 5-500 pmol L(-1), with a detection limit of 2 pmol L(-1). The presence of up to 200-fold greater concentrations of other common metal ions did not interfere with the detection of Hg(2+) ions in an aqueous system, and the results corresponded well with those obtained by ICP-MS. This novel plasmon-enhanced photoelectrochemical aptasensor exhibited good performance with its high sensitivity, good selectivity, low cost, and portable features. The strategy of the localized surface plasmon resonance through the in situ generation of noble metal nanoparticles paves the way for improvements in PEC aptasensor performance.

Effect of various absorption enhancers based on tight junctions on the intestinal absorption of forsythoside A in Shuang-Huang-Lian, application to its antivirus activity

Background:Forsythoside A (FTA), one of the main active ingredients in Shuang–Huang–Lian (SHL), possesses strong antibacterial, antioxidant and antiviral effects, and its pharmacological effects was higher than that of other ingredients, but the absolute bioavailability orally was approximately 0.72%, which was significantly low, influencing clinical efficacies of its oral preparations seriously.Materials and Methods:In vitro Caco-2 cell and in vivo pharmacokinetics study were simultaneously performed to investigate the effects of absorption enhancers based on tight junctions: sodium caprate and water-soluble chitosan on the intestinal absorption of FTA, and the eventual mucosal epithelial damage resulted from absorption enhancers was evaluated by MTT test and morphology observation, respectively. The pharmacological effects such as antivirus activity improvement by absorption enhancers were verified by MDCK damage inhibition rate after influenza virus propagation.Results:The observations from in vitro Caco-2 cell showed that the absorption of FTA in SHL could be improved by absorption enhancers. Meanwhile, the absorption enhancing effect of water-soluble chitosan may be almost saturable up to 0.0032% (w/v), and sodium caprate at concentrations up to 0.64 mg/mL was safe, but water-soluble chitosan at different concentrations was all safe for these cells. In pharmacokinetics study, water-soluble chitosan at dosage of 50 mg/kg improved the bioavailability of FTA in SHL to the greatest extent, and was safe for gastrointestine from morphological observation. Besides, treatment with SHL with water-soluble chitosan at dosage of 50 mg/kg prevented MDCK damage after influenza virus propagation better significantly than that of control.Conclusion:Water-soluble chitosan at dosage of 50 mg/kg might be safe and effective absorption enhancer for improving the bioavailability of FTA and the antivirus activity in vitro in SHL.

Effect of absorption enhancers on the absorption of FD-4 as a poorly absorbable marker macromolecule from the liver surface in rats

The purpose of this study is to improve the rate at which drugs are absorbed from the liver surface by utilizing absorption enhancers such as extracted saponin from Saponaria officinalis (saponin), sodium caprate (Na-Cap), sodium salicylate (Na-Sal), and disodium ethylenediamine-tetraacetic acid. Fluorescein isothiocyanete-dextran with molecular weights of 4400 (FD-4) as a poorly absorbable marker macromolecule was applied to the rat liver using a cylindrical diffusion cell, in the presence or absence of the absorption enhancers. After a 15-min pre-treatment with or the co-administration of saponin or Na-Cap, the absorption ratios of FD-4 and plasma area under the curve were significantly increased, compared to control values. On the other hand, the absorption of FD-4 was increased by a 30-min pre-treatment with Na-Sal. The absorption of FD-4 applied to the rat liver was promoted by absorption enhancers. This approach could have therapeutic use for poorly absorbable compounds.

Improvement of Intestinal Absorption of Poorly Absorbable Drugs by Various Sugar Esters

Effects of sucrose fatty acid esters (sugar esters) on the intestinal absorption of poorly absorbable drugs were examined by an in situ closed loop method in rats. 5(6)-Carboxyfluorescein (CF) and fluorescein isothiocyanate-dextrans (FDs) with various molecular weights were used as model drugs of poorly absorbable drugs. The absorption of CF from the rat small intestine was significantly enhanced in the presence of various sugar esters and a maximal absorption enhancing effect was observed in the presence of 0.5%(w/v) S-1670. The absorption enhancing effect of S-1670 in the small intestine decreased as the molecular weights of drugs increased. Moreover, we evaluated the intestinal membrane damage with or without various sugar esters. These sugar esters (0.5%(w/v)) did not increase the activities of lactate dehydrogenase (LDH), suggesting that these sugar esters did not cause serious membrane damage to the intestinal epithelium. Furthermore, these sugar esters increased membrane fluidity of lipid layers of the intestinal brush border membranes and decreased the transepithelial electrical resistance (TEER) of Caco-2 cells. Therefore, these findings suggested that these sugar esters might improve the intestinal absorption of poorly absorbable drugs via a transcellular and a paracellular pathways.

Precipitating Amino Acid Solvents for CO2 Capture. Opportunities to Reduce Costs in Post Combustion Capture.

Post-combustion CO2 capture based on absorption and thermal desorption is considered a suitable technology for carbon abatement in fossil fuelled power plants. The economic viability of post-combustion capture has been widely studied. The major drawbacks of this technology are the efficiency penalties and high operating cost related to solvent regeneration and CO2 compression, and the potential emission of harmful solvent components. Precipitating amino acid solvents are an alternative to conventional amine scrubbing for CO2 capture from flue gas. These solvents are non-volatile and less toxic than conventional amines. Therefore, the environmental risk related to the emissions of solvent is drastically reduced. Nevertheless, the capture operation with these solvents leads to the formation of precipitates during absorption, which need to be handled in a controlled manner to successfully design a viable process. This work evaluates the technical feasibility of process configurations that contribute to reduce the overall energy use of capture processes based on precipitating amino acid solvents. The process configurations are based on absorption and desorption enhancement effects that are directly or indirectly related to precipitation. The conceptual design of new processes (DECAB and DECAB Plus) based on aqueous solutions of potassium taurate and potassium alanate is described and used to evaluate the performance of these processes. The design is supported by experimental data previously published in the literature. The integration of these process concepts into a coal fired power plant has been evaluated by process simulation of the steam cycle with Aspen Plus ® combined with the capture process requirements estimated by an equilibrium model of the capture process that approximates the thermodynamics of the solvents considered. The DECAB Plus configuration has a net beneficial impact on the energy use of the capture process. The best configuration studied is the DECAB Plus with LVC, which provides up to 4% more power output than the MEA baseline with LVC.

Process Modifications for Solvent-based Post Combustion CO2 Capture

Abstract Amine based CO 2 scrubbing processes have been patented since 1930 but very few process improvements have been reported prior to the oil crisis of 1975-1980, which led to the requirement for more energy efficient processes. Nevertheless most of these patents are solvent oriented. With CO 2 capture technology development, a sharp increase of process improvement patents and scientific articles can be witnessed since 2004 in parallel with the development of new solvents. In this work, a thorough review of patent database and open literature has been carried out in order to be as exhaustive as possible. The individual process modifications and patents are analyzed and then generalised into “elementary” modification groups. These elementary modifications are then sorted into main categories related to their effect on the process. In total, 20 elementary modifications have been sorted into three main categories: absorption enhancement (increasing rich loading or reducing absorption driving force difference along column height), thermal integration (minimizing the rejected heat of process and excessive thermal driving force) and heat pump effect (increasing heat quality with electricity). Figure 1 summarizes these modifications and shows an illustrative flow scheme for each of them. In the final paper, their mean of action will be described and discussed in relation to their induced complexity, flexibility, cost and expected performances.

Surface-modified solid lipid nanoparticles for oral delivery of docetaxel: enhanced intestinal absorption and lymphatic uptake

Docetaxel is a potent anticancer drug, but development of an oral formulation has been hindered mainly due to its poor oral bioavailability. In this study, solid lipid nanoparticles (SLNs) surface-modified by Tween 80 or D-alpha-tocopheryl poly(ethylene glycol 1000) succinate (TPGS 1000) were prepared and evaluated in terms of their feasibility as oral delivery systems for docetaxel. Tween 80-emulsified and TPGS 1000-emulsified tristearin-based lipidic nanoparticles were prepared by a solvent-diffusion method, and their particle size distribution, zeta potential, drug loading, and particle morphology were characterized. An in vitro release study showed a sustained-release profile of docetaxel from the SLNs compared with an intravenous docetaxel formulation (Taxotere®). Tween 80-emulsified SLNs showed enhanced intestinal absorption, lymphatic uptake, and relative oral bioavailability of docetaxel compared with Taxotere in rats. These results may be attributable to the absorption-enhancing effects of the tristearin nanoparticle. Moreover, compared with Tween 80-emulsified SLNs, the intestinal absorption and relative oral bioavailability of docetaxel in rats were further improved in TPGS 1000-emulsified SLNs, probably due to better inhibition of drug efflux by TPGS 1000, along with intestinal lymphatic uptake. Taken together, it is worth noting that these surface-modified SLNs may serve as efficient oral delivery systems for docetaxel.

Time-Resolved Fluorescence Anisotropy of Surface Plasmon Coupled Emission on Metallic Gratings

The unique characteristics of surface plasmon coupled emission (SPCE) made it useful for potential applications in the fields of plasmonic optics and biological sensing. However, the mechanism of SPCE is still under debate. We studied the time-resolved fluorescence anisotropy of SPCE excluding the interference of absorption-enhancement effect by the time-correlated single-photon counting (TCSPC) setups. The value of anisotropy at SPCE peak kept constant at −0.45 during the whole relaxation process, which is in agreement with the calculated value. Our work presented a further step toward the understanding of SPCE.

Effect of Multienzymes and Absorption Enhancers on Productive Performance, Gut Morphology and Some Blood Biochemical and Hormonal Parameters in Broiler Chicks

The present study was carried out to investigate the effect of polyzyme and lysoforte either alone or in combination on productive performance and some metabolic parameters in broiler chicks. Two hundred and forty, one day old, Cobb chicks were divided into four groups, the first group was fed on a basal ration without any additives and kept as a control, the second group was fed on a basal ration supplemented with polyzyme at a dose of 400 gm/ton ration, the third group was fed on a basal ration to which lysoforte was added at a dose of 250 gm/ton ration and the fourth group was fed on a basal diet to which polyzyme 400 g/ton and lysoforte 250 g/ton were added. Both feed additives either alone or in combination produced a significant improvement in body weight, body weight gain and feed conversion ratio during most of the first seven weeks. All supplemented groups showed no significant changes in the activities of ALP, AST, ALT and levels of creatinine and cholesterol versus control during the whole sampling periods. Polyzyme induced a significant increase in serum triglycerides level at the 4th week of the experiment, while at the 6th and 8th week both polyzyme and lysoforte produced a significant increase in its level versus control. Blood glucose level was significantly increased in lysoforte supplemented groups at the 6th weeks and in polyzyme and lysoforte supplemented groups at the 8th weeks. No significant changes in TSH and T4 levels were recorded during the whole sampling periods. At the 8th week the control group exhibited the lowest level of T3. The length of villi and depth of crypts of small intestine of supplemented groups were significantly higher than those of the control groups. All feed additives did not produce any obvious histopathological changes in the examined organs.

Effect of chito-oligosaccharide on the oral absorptions of phenolic acids of Flos Lonicerae extract

Phenolic acids, the main active ingredients in Flos Lonicerae extract possess strong antibacterial, antioxidant and antiviral effects, and their contents was higher largely than that of other ingredients such as flavones, but the absolute bioavailability orally was significantly low, which is significant low influencing clinical efficacies of its oral preparations. In the present study, in vitro Caco-2 cell, in situ single-pass intestinal perfusion and in vivo pharmacokinetics study were performed to investigate the effects of COS on the intestinal absorption of phenolic acids. The pharmacological effects such as antiviral activity improvement by COS were verified by MDCK cell damage inhibition rate after influenza virus propagation. The observations from in vitro Caco-2 cell showed that the absorption of phenolic acids in Flos Lonicerae extract could be improved by COS. Meanwhile, COS at the same low, medium and high concentrations caused a significant, concentration-dependent increase in the Papp-value for phenolic acids compared to the control group (p<0.05), and was all safe for the Caco-2 cells. The observations from single-pass intestinal perfusion in situ model showed that the intestinal absorption of phenolic acids can be enhanced by COS. Meanwhile, the absorption enhancing effect of phenolic acids might be saturable in different intestine sites. In pharmacokinetics study, COS at dosage of 25mg/kg improved the bioavailability of phenolic acids in Flos Lonicerae extract to the greatest extent, and was safe for gastrointestine from morphological observation. Besides, treatment with Flos Lonicerae extract with COS at dosage of 25mg/kg prevented MDCK cell damage upon influenza virus propagation better than that of control. All findings above suggested that COS at dosage of 25mg/kg might be safe and effective absorption enhancer for improving the bioavailability of phenolic acids and the antiviral activity in vitro in Flos Lonicerae extract.

Characteristics of reversible absorption-enhancing effect of sodium nitroprusside in rat small intestine

Nitric oxide (NO) donors increase the permeability of water-soluble compounds with neither loss of cell viability nor lactate dehydrogenase release. In addition, the rectal absorption of insulin has been reported to be remarkably enhanced in the presence of NO donors such as 1-Hydroxy-3-(3-aminopropyl)-3-isopropyltriazene 2-oxide (NOC5) and N-Ethyl-2-(1-ethyl-2-hydroxy-2-nitrosohydrazino) ethanamine (NOC12). In this study, we examined the effect of sodium nitroprusside (SNP), which is used in clinical situations as a vasodilator, as a model NO donor on the ileal mucosa of rats. We used an in situ closed loop method in rat ileum to study changes in the permeability of fluorescein isothiocyanate dextran 4000 (FD-4) as a paracellular marker. The effect of SNP (1 and 10mg/kg) on the protein expression level of the claudin family was examined by Western blotting. The membrane permeation of FD-4 was increased but no mucosal lesion was observed upon the administration of SNP. Moreover, the protein expression level of the claudin family was not changed by the administration of SNP. When SNP was removed 2h after its administration, no significant change in the membrane permeation of FD-4 was observed. Moreover, no decrease of ileal membrane resistance or disruption of membrane structure was observed. The absorption-enhancing effect of SNP was associated with low injury and low toxicity. The reversibility of the effect of SNP was observed. Consequently, it was shown that SNP can be a useful absorption enhancer.

N-octyl-N-arginine-chitosan (OACS) micelles for gambogic acid oral delivery: preparation, characterization and its study on in situ intestinal perfusion

Context: Gambogic acid (GA) can inhibit the growth of various cancer cells. However, the low bioavailability caused by insolubility, limits its clinical application. L-arginine is always used with GA to form a complex to obtain the higher solubility. Moreover, guanidyl group from arginine, which can facilitate the cellular uptake, was identified.Objective: In this study, L-arginine and chitosan (CS) were used for the first time to prepare N-octyl-N-arginine CS (OACS), a novel amphiphilic carrier for GA with solubility- and absorption-enhancing functions; the characterization of the GA loaded OACS micelles (GA-OACS) and its absorption-enhancing effect were also investigated.Materials and methods: GA-OACS were prepared by the dialysis method. The formed micelles were characterized and evaluated by atomic force microscope (AFM), dynamic light scattering, differential scanning calorimeter (DSC), solubility test, in vitro release and in situ intestinal perfusion.Results: The GA-OACS micelles were successfully prepared attaining a 35.3% drug loading and 82.2% entrapment efficiency. GA-OACS had a homogeneous particle size of 160.3 nm; +21.8 mv zeta potential with smooth continuous surface was observed by using AFM. DSC diagram suggested that GA was encapsulated in the micelles. Meanwhile, GA encapsulated in micelles exhibited a desirable slow release in vitro experiment. The solubility of GA in OACS micelles was increased up to 3.16 ± 0.13 mg/mL, 2320 times than that of free GA. The single pass perfusion showed that the absorption of GA-OACS micelles was enhanced 3.6-fold, 2.1-fold and 2.2-fold for jejunum, ileum and colon, respectively.Discussion and conclusion: OACS provided excellent ability of drug loading, increasing solubility and enhanced absorption for GA, which indicated that OACS micelles as an oral drug delivery carrier may have potential research and application values.

Light trapping schemes in organic solar cells: A comparison between optical Tamm states and Fabry–Pérot cavity modes

Recently optical Tamm states at metal/photonic crystals interface have been applied in thin-film organic solar cells (OSCs) as a new light trapping scheme for photon absorption enhancement. In this work, we theoretically investigate this scheme thoroughly to optimize the absorption performance for such optical Tamm states based OSCs (OTS–OSCs). We find that the overall absorptivity of the OTS–OSCs can be improved by using photonic crystals bilayers with a higher refractive index contrast, which is a result of the more strongly enhanced field intensity in the active layers. The conventional Fabry–Pérot cavity modes based OSCs (FP–OSCs) are also studied for comparison, whose absorption performance is found to be strongly dependent on the refractive index of the additional dielectric layer. These two schemes based OSCs exhibit comparable absorption performance in aspects of absorption enhancement, field distributions, and angle effect in the planar case. However, the proposed OTS–OSCs exhibit ∼10% higher overall absorptivity than that for the FP–OSCs in the corrugated case, if both OSCs exhibit the same overall absorptivity in the planar case. The reduced absorption in the corrugated FP–OSCs is a result of the strong scatterings induced losses in the metal, which can be avoided by the photonic crystals bilayers in the OTS–OSCs. Therefore, the proposed Tamm states based scheme shows a higher value in corrugated OSCs.

A Novel Hybrid Integrated Photodetector Based on a Cone Absorption Cavity

A novel hybrid integrated photodetector with flat-top steep-edge spectral response, which consists of a Si-based multi-cavity Fabry-Perot (F-P) filter and an InP-based cone absorption cavity (with a 0.2 m In0.53Ga0.47As absorption layer), has been designed and fabricated. The operating lightwave is well confined to the cone absorption, and experiences multiple reflections across the absorption layer. Thus, an absorption enhancement effect without resonance can be achieved. Based on multi-cavity F-P structure and a cone cavity, this device can get good flat-top steep-edge spectral response and high quantum efficiency. The photodetector is fabricated by bonding a Si-based multi-cavity F-P filter with an InP-based cone absorption cavity. An integrated device with a peak quantum efficiency of 60% around 1550 nm, the dB band of 0.5 nm, and the 25 dB band of 1.06 nm, is simultaneously obtained.

Pharmacokinetic evaluation in mice of amorphous itraconazole-based dry powder formulations for inhalation with high bioavailability and extended lung retention

Three Itraconazole (ITZ) dry powders for inhalation (DPI) were prepared by spray-drying a mannitol solution in which the ITZ was in suspension (F1) or was in solution without (F2) or with phospholipid (PL) (F3). These powders were endotracheally insufflated in vivo at a single dose of 0.5mg/kg for pharmacokinetic profile (lung and plasma concentration) determination in ICR CD-1 mice. ITZ was crystalline in F1 and assumed to be amorphous in the F2 and F3 formulations. F2 and F3 formulations allowed the in vitro formation of an ITZ supersaturated solution with a maximum solubility of 450±124ng/ml (F2) and 498±44ng/ml (F3), in contrast to formulation F1 (<10ng/ml). As a result of these higher solubilities, absorption into the systemic compartment after endotracheal administration was faster for formulations F2 and F3 (shorter tmax) and in larger quantities compared to the F1 formulation (plasmatic AUC0–24h of 182ngh/ml, 491.5ngh/ml and 376.8ngh/ml, and tmax of 60min, 30min and 5min for F1, F2 and F3, respectively). PL increased the systemic bioavailability of ITZ (determined by the AUCplasma to AUClung ratio) as a consequence of their wetting and absorption enhancement effect. ITZ lung concentrations after pulmonary administration remained higher than the targeted dose, based on the minimal inhibitory concentrations for Aspergillus fumigatus (2μg/glung), 24h post-administration for both F1 and F2 formulations. However, this was not the case for formulation F3, which exhibited a faster elimination rate from the lung, with an elimination half-life of 4.1h vs. 6.5h and 14.7h for F1 and F2, respectively.

Absorption Enhancing Effect of Sodium Dodecyl Sulfate on Metformin Hydrochloride in Rat Colon

The aim of this study was to observe the absorption enhancing effect of sodium dodecyl sulfate on metformin hydrochloride in colon of rat. Using in vivo intestinal loop model in rat while the ileum was took as blank group and colon as the experiment groups with different concentration of sodium dodecyl sulfate (1%, 2%, 4%). The colon/ileum ratio of the absorption rate constant of metformin hydrochloride was evaluated through calculating the residual dose of circulating solution in presupposition time points. Intergroup absorption rate constant and the rising percent of the absorption rate constant were different significantly (P&lt;0.05). The absorption rate constant of colon were -0.22±0.03, -0.37±0.06, -0.89±0.09, -0.86±0.05μg•h-1•cm-1 (n=6) and the rising percent of the constant absorption value were 68.66 ± 8.28%, 304.88 ± 28.76%, 293.75 ± 33.19% (n=6), respectively. The result showed that the absorption of metformin hydrochloride was increased with the concentration of sodium dodecyl sulfate. However, the absorption rate constant reached maxium when the concentration of sodium dodecyl sulfate was 2%, this may be because the circulating metformin hydrochloride solution could be more viscous which affect the absorption of metformin hydrochloride when sodium dodecyl sulfate was raised. In conclusion, the absorption of metformin hydrochloride can be promoted by sodium dodecyl sulfate in the colon of rat and this can provide biophamaceutics data for novel pharmaceutical preparation.

PVP and surfactant combined carrier as an effective absorption enhancer of poorly soluble astilbin in vitro and in vivo

Context: Astilbin is considered to be a new and promising immunosuppressant for immune related diseases, but limited in clinical application due to its poor water solubility, difficult oral absorption and low bioavailability.Objective: The present work studied the effect of PVP and surfactant combined carrier on its capability to improve drug absorption.Materials and methods: PVP K30-Tween 80 combined carries was applied into the astilbin solid dispersions, tested both in vivo in beagle dogs and in vitro in transport experiments across Caco-2 cell monolayers.Results and discussion: In the animal studies a many fold increase in plasma AUC was observed for the solid dispersions of drug in PVP K30-Tween 80 combined carries compared to active pharmaceutical ingredient (API). The applicability of Caco-2 monolayers as a tool for predicting the in vivo transport behavior of Astilbin in combination with a solubility enhancing carries was shown. In vitro transport studies confirmed the effect of combined carries on the absorption behavior of the astilbin. MTT studies showed the cell viability gradually decreased with the increase of the drug concentration in a dose dependent manner for astilbin and that in solid dispersions. The permeability and apparent permeability coefficients (Papp) increased with drug in the Caco-2 cell.Conclusion: In this study, it was found that PVP K30 and Tween 80 promoted the permeability of drugs best within a certain amount. For astilbin PVP K30 and surfactant combined carrier had a strong potential to improve oral bioavailability.