Solutions for Lipophilic Drugs: A Biodegradable Polymer Acting as Solvent, Matrix, and Carrier to Solve Drug Delivery Issues

The order affects the release of vitamin D from hybrid self-assembled silica systems

Vitamin D (VD) suffers from low water solubility and strong degradation, which both decrease its bioavailability. This work aims at obtaining a silica-surfactant-VD hybrid material and verifying if this system can protect VD from degradation and enhance its solubility. This preliminary study aspires at tuning the mesostructure order of the hybrid system (by modifying the surfactant amount) with the scope of controlling, somewhat, its drug release capability. To this purpose, two silica-surfactant-VD systems with different long-range order were synthesized and characterized in terms of physico-chemical properties and release behavior in a model solution mimicking the topical environment. Results show that the hybrid materials are able to incorporate VD, protect it from degradation up to 17 months and release it in aqueous media. The mesostructure order and the interaction between VD, surfactant and silica seem to play a key role in tuning kinetics and the amount of released drug. While the less ordered structure incorporates less VD with faster and higher release percentage, the more ordered one incorporates more VD but, due to the stronger interactions with the carrier, requires a partial dissolution of the matrix to occur before releasing the drug, so inducing a lag-time and a smaller released quantity.

Biobased Ionic Liquids as Multitalented Materials in Lipidic Drug Implants

Lipidic implants are valuable controlled delivery systems that present good biocompatibility and are useful for long-lasting therapies. However, these promising systems can present inflexible drug release profiles that limit their performance. Thus, finding new materials to overcome this drawback is crucial. Herein, lipidic implants containing caffeine and poorly soluble salicylic acid and rutin were developed. The inclusion of Gelucire^® 50/02, sucrose, and two biobased ionic liquids, [Cho][Phe] and [Cho][Glu], were evaluated as a mean to improve the performance of the systems. The formulation procedure, dye content distribution, drug content, drug release, water content, and lipidic erosion of the developed systems were assessed. AFM analysis of the implants containing ILs was also performed. The results demonstrated that neither Gelucire^® 50/02 nor sucrose were suitable tools to improve the drug release profile. In contrast, the ILs proved to be promising materials for multiple reasons; not only did they facilitate the formulation and incorporation of the studied drugs into the implants, but they also allowed a more suitable release profile, with [Cho][Glu] allowing a higher drug release due to its ability to increase surface wrinkling. Hence, this study showcases ILs as multitalented materials in lipid-based drug implants.

Drug delivery's quest for polymers: Where are the frontiers?

Since the legendary 1964 article of Folkman and Long entitled "The use of silicone rubber as a carrier for prolonged drug therapy" the role of polymers in controlled drug delivery has come a long way. Today it is evident that polymers play a crucial if not the prime role in this field. The latest boost owes to the interest in drug delivery for the purpose of tissue engineering in regenerative medicine. The focus of this commentary is on a selection of general and personal observations that are characteristic for the current state of polymer therapeutics and carriers. It briefly highlights selected examples for the long march of synthetic polymer-drug conjugates from bench to bedside, comments on the ambivalence of selected polymers as inert excipients versus biological response modifiers, and on the yet unsolved dilemma of cationic polymers for the delivery of nucleic acid therapeutics. Further subjects are the complex design of multifunctional polymeric carriers including recent concepts towards functional supramolecular polymers, as well as observations on stimuli-sensitive polymers and the currently ongoing trend towards natural and naturally-derived biopolymers. The final topic is the discovery and early development of a novel type of biodegradable polyesters for parenteral use. Altogether, it is not the basic and applied research in polymer therapeutics and carriers, but the translational process that is the key hurdle to proceed towards an authoritative approval of new polymer therapeutics and carriers.

New perspectives in cell delivery systems for tissue regeneration: natural-derived injectable hydrogels

Natural polymers, because of their biocompatibility, availability, and physico-chemical properties have been the materials of choice for the fabrication of injectable hydrogels for regenerative medicine. In particular, they are appealing materials for delivery systems and provide sustained and controlled release of drugs, proteins, gene, cells, and other active biomolecules immobilized.In this work, the use of hydrogels obtained from natural source polymers as cell delivery systems is discussed. These materials were investigated for the repair of cartilage, bone, adipose tissue, intervertebral disc, neural, and cardiac tissue. Papers from the last ten years were considered, with a particular focus on the advances of the last five years. A critical discussion is centered on new perspectives and challenges in the regeneration of specific tissues, with the aim of highlighting the limits of current systems and possible future advancements.