Abstract
Background and Objectives: The selective kappa opioid receptor agonist U50,488 was reported to have analgesic, cough suppressant, diuretic and other beneficial properties. The aim of our study was to analyze the effects of some original chitosan-coated liposomes entrapping U50,488 in somatic and visceral nociceptive sensitivity in mice. Materials and Methods: The influence on the somatic pain was assessed using a tail flick test by counting the tail reactivity to thermal noxious stimulation. The nociceptive visceral estimation was performed using the writhing test in order to evaluate the behavioral manifestations occurring as a reaction to the chemical noxious peritoneal irritation with 0.6% acetic acid (10 mL/kbw). The animals were treated orally, at the same time, with a single dose of: distilled water 0.1 mL/10 gbw; 50 mg/kbw U50,488; 50 mg/kbw U50,488 entrapped in chitosan-coated liposomes, according to the group they were randomly assigned. Results: The use of chitosan-coated liposomesas carriers for U50,488 induced antinociceptive effects that began to manifest after 2 h, andwere prolonged but with a lower intensity than those caused by the free selective kappa opioid in both tests. Conclusion: In this experimental model, the oral administration of nanovesicles containing the selective kappa opioid agonist U50,488 determined a prolonged analgesic outcome in the tail flick test, as well as in the writhing test.
Highlights
Nanomedicine offers valuable research and practical application tools in clinical medicine, improving the currently used methods of prevention, diagnosis, targeted therapy in various pathological conditions, from simple inflammatory illnesses to neoplastic diseases [1].The application of nanotechnology in the development of new drug formulations has opened a new area of researching the prolonged release of different pharmacologically active substances.The drug-carrying nanoformulations consist of solid biodegradable particles, with the size varying between 10 and 1000 nm, in which the active ingredient is dissolved, trapped, or encapsulated and/or in which the active substance is absorbed or attached [2]
The obtained chitosan-coated liposomes entrapping U50,488 proved to have a mean of 12 size of 572 nm (Figure 1)
The use of chitosan was associated by an augmentation of5 the vesicles dimension, determining a stiffening of the bilayers
Summary
Nanomedicine offers valuable research and practical application tools in clinical medicine, improving the currently used methods of prevention, diagnosis, targeted therapy in various pathological conditions, from simple inflammatory illnesses to neoplastic diseases [1].The application of nanotechnology in the development of new drug formulations has opened a new area of researching the prolonged release of different pharmacologically active substances.The drug-carrying nanoformulations consist of solid biodegradable particles, with the size varying between 10 and 1000 nm, in which the active ingredient is dissolved, trapped, or encapsulated and/or in which the active substance is absorbed or attached [2]. Liposomes are systems with a high variation in shape and surface electric charge, and in the composition of the lipid component, which determines the differences in permeability through biological membranes. The composition of the lipid bilayer has an essential role in modulating the fluidity of the vesicular membrane; this element contributesto the stability of liposomes, andalso to the kinetic model of releasing the encapsulated components [4,5].Vesicles can carry both hydrophilic and hydrophobic molecules. In the preparation of vesicles, a very important role is played by the geometry of amphiphilic molecules, because only cylindrical molecules form bilayers These can be both lipids (two-tailed biological molecules) and a mixture of single-tailed surfactants of opposite charge [3,4]
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