ABSTRACT
Topotecan is a relatively large, planar, asymmetric and polar molecule with a lactone moiety. In neutral or basic aqueous solutions, this ring opens forming the carboxylate form of Topotecan that is biologically inactive and uncapable of passively cross membranes. Nevertheless, despite this inability to cross membranes at this form, Topotecan may still be able to interact with phospholipid bilayers, disturbing them. In this context, phospholipid models, mimicking normal (DMPC at pHâ¯7.4) and cancer cell lipid membranes (DMPC:DMPS (5:1) at pHâ¯6.5), were used to assess structural modifications upon interaction with Topotecan. Langmuir isotherms of monolayers coupled with Brewster angle microscopy, differential scanning calorimetry of liposomes and X-ray scattering of small and wide angle of stacked multilayers were used as complementary techniques. The overall results show that the interaction of Topotecan with lipid membranes is deeply conditioned by their composition and that Topotecan seems to have a preferential interaction with the glycerol backbone of phosphatidylcholine phospholipids.
Subject(s)
Cell Membrane/drug effects , Dimyristoylphosphatidylcholine/chemistry , Membranes, Artificial , Neoplasms/drug therapy , Topoisomerase I Inhibitors/pharmacology , Topotecan/pharmacology , Animals , Cell Membrane/chemistry , Cell Membrane/metabolism , Cell Membrane Permeability , Dimyristoylphosphatidylcholine/metabolism , Humans , Models, Biological , Molecular Structure , Neoplasms/chemistry , Neoplasms/metabolism , Phosphatidylcholines/chemistry , Phosphatidylcholines/metabolism , Phosphatidylserines/chemistry , Phosphatidylserines/metabolism , Structure-Activity Relationship , Topoisomerase I Inhibitors/chemistry , Topoisomerase I Inhibitors/metabolism , Topotecan/chemistry , Topotecan/metabolismABSTRACT
AIM: The treatment of rheumatoid arthritis remains a challenge as available therapies still entail the risk of deleterious off-target effects. The present study describes hyaluronic acid-conjugated pH-sensitive liposomes as an effective drug delivery-targeting strategy to synovial cells. MATERIALS & METHODS: Therapeutic, cytotoxic and targeting potential of developed liposomes were studied in vitro using macrophages and fibroblasts cell lines. RESULTS & CONCLUSION: Results suggest an enhanced cellular uptake of conjugated liposomes, mainly mediated by caveolae- and clathrin-dependent endocytosis. In vitro release studies demonstrated that prednisolone was preferentially released under acidic conditions mimicking intracellular endosomal compartments. Overall, results revealed that conjugated pH-sensitive liposomes are a promising nanoapproach for the targeted delivery of prednisolone within inflamed synovial cells for rheumatoid arthritis treatment.
Subject(s)
Arthritis, Rheumatoid/drug therapy , Hyaluronic Acid/chemistry , Liposomes/chemistry , Prednisolone/administration & dosage , Prednisolone/therapeutic use , Animals , Cell Line , Endocytosis/drug effects , Fibroblasts/drug effects , Fibroblasts/metabolism , Hydrogen-Ion Concentration , Macrophages/drug effects , Macrophages/metabolism , Magnetic Resonance Spectroscopy , Mice , Prednisolone/chemistry , RAW 264.7 CellsABSTRACT
PURPOSE: Nanostructured Lipid Carriers (NLCs) loading oxaprozin were developed to address an effective drug packaging and targeted delivery, improving the drug pharmacokinetics and pharmacodynamics properties and avoiding the local gastric side-effects. Macrophages actively phagocyte particles with sizes larger than 200 nm and, when activated, over-express folate beta receptors - features that in the case of this work constitute the basis for passive and active targeting strategies. METHODS: Two formulations containing oxaprozin were developed: NLCs with and without folate functionalization. In order to target the macrophages folate receptors, a DSPE-PEG2000-FA conjugate was synthesized and added to the NLCs. RESULTS: These formulations presented a relatively low polydispersity index (approximately 0.2) with mean diameters greater than 200 nm and zeta potential inferior to -40 mV. The encapsulation efficiency of the particles was superior to 95% and the loading capacity was of 9%, approximately. The formulations retained the oxaprozin release in simulated gastric fluid (only around 10%) promoting its release on simulated intestinal fluid. MTT and LDH assays revealed that the formulations only presented cytotoxicity in Caco-2 cells for oxaprozin concentrations superior to 100 µM. Permeability studies in Caco-2 cells shown that oxaprozin encapsulation did not interfered with oxaprozin permeability (around 0.8 × 10(-5) cm/s in simulated intestinal fluid and about 1.45 × 10(-5) cm/s in PBS). Moreover, in RAW 264.7 cells NLCs functionalization promoted an increased uptake over time mainly mediated by a caveolae uptake mechanism. CONCLUSIONS: The developed nanoparticles enclose a great potential for oxaprozin oral administration with significant less gastric side-effects.
