Formulating poorly water soluble drugs using ordered mesoporous silica materials is an emerging approach to tackle solubility-related bioavailability problems. The current study was conducted to assess the bioavailability-enhancing potential of ordered mesoporous silica in man. In this open-label, randomized, two-way cross-over study, 12 overnight fasted healthy volunteers received a single dose of fenofibrate formulated with ordered mesoporous silica or a marketed product based on micronized fenofibrate. Plasma concentrations of fenofibric acid, the pharmacologically active metabolite of fenofibrate, were monitored up to 96h post-dose. The rate (C/dose increased by 77%; t reduced by 0.75h) and extent of absorption (AUC/dose increased by 54%) of fenofibrate were significantly enhanced following administration of the ordered mesoporous silica based formulation. The results of this study serve as a proof of concept in man for this novel formulation approach.
The present study describes utilization of two photon excitation fluorescence (2PE) microscopy for visualization of the hemoglobin in human and porcine erythrocytes and their empty membranes (i.e., ghosts). High-quality, label- and fixation-free visualization of hemoglobin was achieved at excitation wavelength 730 nm by detecting visible autofluorescence. Localization in the suspension and spatial distribution (i.e., mapping) of residual hemoglobin in erythrocyte ghosts has been resolved by 2PE. Prior to the 2PE mapping, the presence of residual hemoglobin in the bulk suspension of erythrocyte ghosts was confirmed by cyanmethemoglobin assay. 2PE analysis revealed that the distribution of hemoglobin in intact erythrocytes follows the cells’ shape. Two types of erythrocytes, human and porcine, characterized with discocyte and echinocyte morphology, respectively, showed significant differences in hemoglobin distribution. The 2PE images have revealed that despite an extensive washing out procedure after gradual hypotonic hemolysis, a certain amount of hemoglobin localized on the intracellular side always remains bound to the membrane and cannot be eliminated. The obtained results open the possibility to use 2PE microscopy to examine hemoglobin distribution in erythrocytes and estimate the purity level of erythrocyte ghosts in biotechnological processes.
The present study aims to evaluate the in vitro and in vivo performance of ordered mesoporous silica (OMS) as a carrier for the poorly water-soluble compound fenofibrate. Fenofibrate was loaded into OMS via incipient wetness impregnation to obtain a 29% drug load and formulated into capsules. Two capsule dosage forms (containing 33.5 and 16.75 mg fenofibrate, respectively) were compared with the commercially available forms-Lipanthyl(®) (fenofibrate microcrystals) and Tricor(®) (fenofibrate nanocrystals). In vitro dissolution tests showed that the amount of fenofibrate released from Lipanthyl(®) and Tricor(®) was approximately 30%, whereas approximately 66% and 60% of the drug was released from OMS capsules containing 33.5 and 16.75 mg of fenofibrate, respectively. Storage of OMS capsules loaded with 33.5 mg of fenofibrate at 25°C/60% relative humidity (RH) or 40°C/75% RH did not alter the release kinetics, nor the physical state of the compound, pointing the stability of the present formulation. The in vivo study in dogs confirmed satisfying level of safety and tolerability of fenofibrate-OMS formulation (eq. 33.5 mg) with the potential to improve the absorption of fenofibrate. Though some variability in the data, this formulation is promising to be further investigated in a clinical trial setting.
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