Evaluation of an oleic acid water-in-oil-in-water-type multiple emulsion as potential drug carrier via the enteral route

Dynamics of deformation and pinch-off of a migrating compound droplet in a tube

A computational fluid dynamic investigation has been carried out to study the dynamics of a moving compound droplet inside a tube. The motions associated with such a droplet is uncovered by solving the axisymmetric Navier-Stokes equations in which the spatiotemporal evolution of a pair of twin-deformable interfaces has been tracked employing the volume-of-fluid approach. The deformations at the interfaces and their subsequent dynamics are found to be stimulated by the subtle interplay between the capillary and viscous forces. The simulations uncover that when a compound drop composed of concentric inner and outer interfaces migrates inside a tube, initially in the unsteady domain of evolution, the inner drop shifts away from the concentric position to reach a morphology of constant eccentricity at the steady state. The coupled motions of the droplets in the unsteady regime causes a continuous deformation of the inner and outer interfaces to obtain a configuration with a (an) prolate (oblate) shaped outer (inner) interface. The magnitudes of capillary number and viscosity ratio are found to have significant influence on the temporal evolution of the interfacial deformations as well as the eccentricity of the droplets. Further, the simulations uncover that, following the asymmetric deformation of the interfaces, the migrating compound droplet can undergo an uncommon breakup stimulated by a rather irregular pinch-off of the outer shell. The breakup is found to initiate with the thinning of the outer shell followed by the pinch-off. Interestingly, the kinetics of the thinning of outer shell is found to follow two distinct power-law regimes-a swiftly thinning stage at the onset followed by a rate limiting stage before pinch-off, which eventually leads to the uncommon breakup of the migrating compound droplets.

Intestinal permeation enhancers for oral peptide delivery

Intestinal permeation enhancers (PEs) are one of the most widely tested strategies to improve oral delivery of therapeutic peptides. This article assesses the intestinal permeation enhancement action of over 250 PEs that have been tested in intestinal delivery models. In depth analysis of pre-clinical data is presented for PEs as components of proprietary delivery systems that have progressed to clinical trials. Given the importance of co-presentation of sufficiently high concentrations of PE and peptide at the small intestinal epithelium, there is an emphasis on studies where PEs have been formulated with poorly permeable molecules in solid dosage forms and lipoidal dispersions.

Surface-modified solid lipid nanoparticulate formulation for ifosfamide: development and characterization

Aims: The present research focuses on the development of the surface modified solid lipid nanoparticulate (SLN) system for enhancing the stability and sustaining the release of a model hydrophilic drug ifosfamide. Materials & Methods: SLNs consisting of glyceryl monooleate (GMO) and chitosan were prepared by double emulsion technique, crosslinked with sodium tripolyphosphate, followed by lyophilization under two different vacuum conditions. The physicochemical characterization of SLNs included evaluation of surface morphology, particle size and surface charge, moisture content and physical state of the drug in the delivery system. The in vitro drug release and the stability were evaluated using high-performance liquid chromatography and liquid chromatography/mass spectrometry, respectively. Cellular permeability and subcellular localization studies were performed using Caco-2 cells. Results: Different chamber pressures during lyophilization produced SLNs with different morphologies and moisture contents. SLNs demonstrated high encapsulation efficiency, sustained release, and enhanced stability of ifosfamide with a high cellular uptake and permeability for Caco-2 cells. Conclusion: GMO and chitosan SLNs could be successfully used for enhancing the stability, sustaining the release, enhancing the targeting and permeability characteristics of ifosfamide.

Association with oleic acid vesicles enhances manganese III mesoporphyrin absorption and biliary elimination in rats

OBJECTIVE

To determine whether the association of manganese III mesoporphyrin (MnMeso), an oral MR contrast agent, to oleic acid (OA) vesicles will improve absorption and delivery of MnMeso to the liver.

METHODS

MnMeso or MnMeso-OA vesicle suspension was intraduodenally administered to rats and the time course of MnMeso concentration in plasma, bile, and intestinal solution was determined. Tissue concentrations of MnMeso in the liver were also determined.

RESULTS

Association of MnMeso to OA reduced the time it took to reach one-half absorption maximum, TC50, and enhanced the rate and the extent of biliary elimination of this contrast agent. In addition, the results obtained from dose-titration studies indicate that MnMeso-OA vesicle complex may enhance MnMeso accumulation in the liver, observed as a lower dose required to reach equivalent tissue concentration. Taken together, complexion to OA vesicles may provide rapid absorption, enhanced liver accumulation, and efficient elimination of MnMeso.

CONCLUSIONS

Association with OA vesicles may enhance the rate of MnMeso absorption and biliary excretion while promoting the extent of liver accumulation of MnMeso in rats. This strategy may provide a means to provide safe and effective use of MnMeso as an MR contrast medium.

The role of mixed micelles in drug delivery. I. Solubilization

The present study revealed that the solubilization of a poorly soluble drug, Amphotericin-B (AmB) can be improved by lipid-bile salt mixed micelles and it was also noted that mixed micellar systems are thermodynamically stable relative to micellar systems. It was observed that the degradation or precipitation of AmB was significantly reduced when stored at 8 degrees C. The mixed micellar systems composed of sodium desoxycholate with monoolein increased the solubilization of AmB by more than seven-fold as compared to nonmicellar systems.

Interaction of manganese-mesoporphyrin with oleic acid vesicles

We investigated the interaction between manganese(III)mesoporphyrin (MnMeso), a metalloporphyrin, and liposome membranes containing oleic acid (OA; cis-9-octadecenoic acid). MnMeso associates preferentially with OA but minimally with egg phosphatidylcholine (EPC). Using small unilamellar vesicles, we characterized the MnMeso-OA binding at neutral pH. Our data suggest that MnMeso binds to the OA bilayer with Kd = 6.8 x 10(-4) M; the binding stoichiometry of MnMeso-OA was 1:3.4. This OA-MnMeso interaction was analyzed further for changes in the T1 relaxation property of MnMeso. OA increased the T1 of MnMeso significantly more than did EPC, suggesting that the OA-MnMeso interaction was stronger than that of PC-MnMeso. The side-chain specificity of the OA interaction with this porphyrin derivative was further supported in an experiment with manganese mesotetra(4-sulfonatophenyl)porphine, which lacks hydrophobic side chains for OA interaction. The association of MnMeso with the OA membrane was proposed according to the structure of MnMeso and OA and further verified using electron microscopy. A strong association of MnMeso with OA, an absorption enhancer of the gastrointestinal tract, may be useful for delivery of MnMeso as an oral contrast agent for magnetic resonance imaging.