Solid Phospholipid Dispersions for Oral Delivery of Poorly Soluble Drugs: Investigation Into Celecoxib Incorporation and Solubility-In Vitro Permeability Enhancement.

Celecoxib (CXB) is a Biopharmaceutical Classification System class II drug in which its oral bioavailability is limited by poor aqueous solubility. Although a range of formulations aiming to increase the solubility of CXB have been developed, it is not completely understood, whether (1) an increase in CXB solubility leads to a subsequent increase in permeability across intestinal barrier and (2) the presence of bile salts affects the solubility and permeability behavior of CXB formulations. By formulating CXB solid phospholipid (PL) dispersions with various PL-to-drug ratios using freeze drying, the present study illustrated that the enhancement of CXB solubility was not proportionally translated into enhanced permeability; both parameters were highly dependent on the PL-to-drug ratios as well as the dispersion media (i.e., the presence of 3-mM sodium taurocholate). This study highlights the importance of evaluating both, solubility and permeability, and the use of biorelevant medium for testing the candidate-enabling performance of liposomal formulations. Mechanisms at molecular level that may explain the effect of PL formulations on the permeability of CXB are also discussed.

Brain targeting effect of camptothecin-loaded solid lipid nanoparticles in rat after intravenous administration.

This study intended to investigate the ability of solid lipid nanoparticles (SLN) to deliver camptothecin into the brain parenchyma after crossing the blood-brain barrier. For that purpose, camptothecin-loaded SLN with mean size below 200 nm, low polydispersity index (<0.25), negative surface charge (-20 mV), and high camptothecin association efficiency (>94%) were produced. Synchrotron small and wide angle X-ray scattering (SAXS/WAXS) analysis indicates that SLN maintain their physical stability in contact with DMPC membrane, whereas SLN change the lamellar structure of DMPC into a cubic phase, which is associated with efficient release of the incorporated drugs. Cytotoxicity studies against glioma and macrophage human cell lines revealed that camptothecin-loaded SLN induced cell death with the lowest maximal inhibitory concentration (IC50) values, revealing higher antitumour activity of camptothecin-loaded SLN against gliomas. Furthermore, in vivo biodistribution studies of intravenous camptothecin-loaded SLN performed in rats proved the positive role of SLN on the brain targeting since significant higher brain accumulation of camptothecin was observed, compared to non-encapsulated drug. Pharmacokinetic studies further demonstrated lower deposition of camptothecin in peripheral organs, when encapsulated into SLN, with consequent decrease in potential side toxicological effects. These results confirmed the potential of camptothecin-loaded SLN for antitumour brain treatments.

Development and validation of a simple reversed-phase HPLC method for the determination of camptothecin in animal organs following administration in solid lipid nanoparticles.

A simple, sensitive and specific high-performance liquid chromatography (HPLC) assay for the quantification of camptothecin (CPT), a potent anticancer candidate, incorporated into solid lipid nanoparticles (SLN) in several rat organs (brain, heart, kidneys liver, lung, spleen) and serum was developed and validated. The sample pre-treatment involved organs homogenisation followed by CPT extraction. The samples were injected onto an analytical reversed-phase (RP) Mediterranea™ Sea18 column maintained at 30°C. The chromatographic separation was achieved by gradient elution consisting of triethyamine buffer pH 5.5 and acetonitrile at a flow rate of 1.2 mL/min in 16 min of run time and retention time of 9.8 min (lactone). Fluorescence detection was used at the excitation and emission of 360 and 440 nm, respectively. The calibration curves in the different organs, serum and in PB3 were linear (r(2)>0.9999) over CPT concentrations ranging from 1 to 200 ng/mL or 0.5 to 200 ng/mL (n=6), respectively. The method was shown to be specific, accurate (between 94.4±4.5% and 108.9±0.6%) and precise at the intra-day and inter-day levels as reflected by the coefficient of variation (CV<6.3%) at three different concentrations (10, 50 and 100 ng/mL) in all matrices. Stability studies showed that CPT was stable in all matrices after 24h of incubation at room temperature (RT), after 24 h in the autosampler or after three freeze/thaw cycles. The mean recoveries of CPT in suspension, loaded into SLN and in a physical mixture with SLN at three concentrations of 10, 50 and 200 ng/mL were higher than 86.4%. The detection limit (DL) was ≤0.2 ng/mL and the quantification limit (QL) was ≤0.5 ng/mL. The method developed is reliable, precise and accurate and can be used in the determination of CPT amount in rat organ samples after i.v. administration of CPT in suspension, in physical mixture with SLN and incorporated in SLN.

Use of declarative statements in creating and maintaining computer-interpretable knowledge bases for guideline-based care.

Developing computer-interpretable clinical practice guidelines (CPGs) to provide decision support for guideline-based care is an extremely labor-intensive task. In the EON/ATHENA and SAGE projects, we formulated substantial portions of CPGs as computable statements that express declarative relationships between patient conditions and possible interventions. We developed query and expression languages that allow a decision-support system (DSS) to evaluate these statements in specific patient situations. A DSS can use these guideline statements in multiple ways, including: (1) as inputs for determining preferred alternatives in decision-making, and (2) as a way to provide targeted commentaries in the clinical information system. The use of these declarative statements significantly reduces the modeling expertise and effort required to create and maintain computer-interpretable knowledge bases for decision-support purpose. We discuss possible implications for sharing of such knowledge bases.