Chitosan: A Good Candidate for Sustained Release Ocular Drug Delivery Systems

This chapter focuses on the eye, one of the most important organs of humans. Current data on pathophysiology of the human eye are presented in direct correlation with a range of therapeutic products, with a well-known and widely used material, namely chitosan. Applications of chitosan biopolymer are described in the development of innovative, modern, therapeutic devices and solutions. Thus, chitosan is a good excipient either for classic drop-type ocular systems, as well as for complex drug systems such as nanostructures (nanoparticles, nanomicelles and nanosuspensions), liposomes, microemulsions, microspheres, in situ hydrogels and inserts or implants. A number of disadvantages for ocular administration of the drugs are thus overcome

Natural and Artificial Superwettable Surfaces-Superficial Phenomena: An Extreme Wettability Scenario

With the help of biomimetics, superficial characteristics were transposed, through various methods, onto artificially obtained materials. Many industrial fields applied surface architecture modifications as improvements of classic materials/methods. The medico-pharmaceutical, biochemical, transportation, and textile fields are few examples of industrial areas welcoming a “structural change.” Anti-bioadhesion was widely exploited by means of antibacterial or self-cleaning fabrics and cell culturing/screening/isolation. Anti-icing, antireflective, and anticorrosion materials/coatings gained attention in the transportation and optical device fields. Interdisciplinary approaches on extreme wettability include “solid-fluid” formations called liquid marbles, which will be further discussed as a superhydrophobic behavior exponent

Promising Hydrogels-Based Dressings for Optimal Treatment of Cutaneous Lesions

Worldwide, cutaneous lesions care represents a daily challenge for the medical system, with an increasing prevalence from year to year (from ~5 million in 2005 to about 8 million in 2018) and high costs for their treatment (between ~$28 billion and ~$97 billion). Injuries are the most frequent and destructive form of skin damage, affecting patients’ quality of life. To promote wound healing, an ideal treatment involves proper dressings that can manage the local pain, inflammation, or infection. Passive or dry traditional dressings, such as cotton, gauze, or lint, have limited therapeutic actions and demand periodic replacement of the dressing. Therefore, an optimal alternative for advanced wound care is represented by hydrogels, one of the five classes of modern dressings, which assure excellent local moisture, due to their high ability to absorb a large volume of water inside their three-dimensional networks. Moreover, hydrogels possess suitable biocompatibility, biodegradability, porosity, elasticity, flexibility, and biological properties similar to the extracellular matrix. This chapter presents the main characteristics of the hydrogels and the recent research regarding the development of new hydrogel dressings, based on natural, semi-synthetic, or synthetic biopolymers, loaded with varied therapeutic agents to stimulate the tissue regeneration of different etiologies cutaneous lesions

STUDIES CONCERNING THE DEVELOPMENT OF LIPID NANOSTRUCTURES IN BIOPRODUCTS ENCAPSULATION

Abstract In recent years, a considerable effort was dedicated to researching methylxantine derivatives (MX

Melatonin: A Silent Regulator of the Glucose Homeostasis

In the human organism, the circadian regulation of carbohydrates metabolism is essential for the glucose homeostasis and energy balance. Unbalances in glucose and insulin tissue and blood levels have been linked to a variety of metabolic disorders such as obesity, metabolic syndrome, cardiovascular diseases and type 2 diabetes. Melatonin, the pineal hormone, is the key mediator molecule for the integration between the cyclic environment and the circadian distribution of physiological and behavioral processes and for the optimization of energy balance and body weight regulation, events that are crucial for a healthy organism. This chapter reviews the interplay between melatonin modulatory physiological effects, glucose homeostasis and metabolic balance, from the endocrinology perspective. The tremendous effect of melatonin in the regulation of metabolic processes is observed from the chronobiology perspective, considering melatonin as a major synchronizer of the circadian internal order of the physiological processes involved in energy metabolism

Biopharmaceutical Profiling of New Antitumor Pyrazole Derivatives

Several new pyrazole derivatives have demonstrated promising antiproliferative and cytotoxic effects, but their poor solubility raised concerns over possible biopharmaceutical limitations. In order to improve their pharmaceutical potential we performed the biopharmaceutical profiling for nine pyrazole compounds using in vitro and computational methods. The experimental solubility was determined in five different media using a validated HPLC method. Although the experimental solubility was lower than the predicted one, a good linear relationship was observed. The results also indicated a minimal impact of endogenous tensioactives on solubility, suggesting dissolution rate limited absorption. The in silico experiments were focused on identification of molecular determinants of solubility, evaluation of drug-likeness, prediction of in vivo absorption based on mechanistic models, as well as identification of the main factors that could impact on the oral bioavailability. The results suggested that dose, solubility and particle size are the main determinants of absorption, whereas permeability has little effect, confirming the BCS Class II behavior of the compounds. The present investigation was able to rank the tested compounds in terms of biopharmaceutical behavior, and indicated the B3 series compounds as having a more favorable absorption profile making them the main candidates for advance to the pre-clinical in vivo studies

Hydrogels - Smart Materials for Biomedical Applications

Hydrogels, as three-dimensional polymer networks, are able to retain a large amount of water in their swollen state. The biomedical application of hydrogels was initially hampered by the toxicity of cross-linking agents and the limitations of hydrogel formation under physiological conditions. However, emerging knowledge in polymer chemistry and an increased understanding of biological processes have resulted in the design of versatile materials and minimally invasive therapies.The novel but challenging properties of hydrogels are attracting the attention of researchers in the biological, medical, and pharmaceutical fields. In the last few years, new methods have been developed for the preparation of hydrophilic polymers and hydrogels, which may be used in future biomedical and drug delivery applications. Such efforts include the synthesis of self-organized nanostructures based on triblock copolymers with applications in controlled drug delivery. These hydrogels could be used as carriers for drug delivery when combined with the techniques of drug imprinting and subsequent release. Engineered protein hydrogels have many potential advantages. They are excellent biomaterials and biodegradables. Furthermore, they could encapsulate drugs and be used in injectable forms to replace surgery, to repair damaged cartilage, in regenerative medicine, or in tissue engineering. Also, they have potential applications in gene therapy, although this field is relatively new

Flow and Thixotropic Parameters for Rheological Characterization of Hydrogels

The goal of this paper was to design several sodium carboxymethylcellulose hydrogels containing a BCS class II model drug and to evaluate their flow and thixotropic properties. The rheological measurements were performed at two temperatures (23 °C and 37 °C), using a rotational viscometer. The hydrogels were stirred at different time intervals (10 s, 2, 5, 10 and 20 min at 23 °C, and 10 s, 2 and 5 min at 37 °C), with a maximum rotational speed of 60 rpm, and the corresponding forward and backward rheograms were recorded as shear stress vs. shear rate. For all hydrogels, the rheological data obtained at both temperatures showed a decrease of viscosity with the increase of the shear rate, highlighting a pseudoplastic behaviour. The flow profiles viscosity vs. shear rate were quantified through power law model, meanwhile the flow curves shear stress vs. shear rate were assessed by applying the Herschel-Bulkley model. The thixotropic character was evaluated through different descriptors: thixotropic area, thixotropic index, thixotropic constant and destructuration thixotropic coefficient. The gel-forming polymer concentration and the rheological experiments temperature significantly influence the flow and thixotropic parameters values of the designed hydrogels. The rheological characteristics described have an impact on the drug release microenvironment and determine the stasis time at the application site