Styrene maleic acid anhydride copolymer (SMA) for the encapsulation of sparingly water-soluble drugs in nanoparticles

Berberine-styrene-co-maleic acid nanomicelles: unlocking opportunities for the treatment and prevention of bacterial infections

The global spread of multi-drug-resistant (MDR) bacteria is rapidly increasing due to antibiotic overuse, posing a major public health threat and causing millions of deaths annually. The present study explored the potential of nanocarriers for delivering novel and alternative antibacterial agents using nanotechnology-based approaches to address the challenge of MDR bacteria. The purpose was to enhance the solubility, stability, and targeted delivery of berberine (BER) and its synthetic derivative NR16 using Styrene-co-Maleic Acid (SMA) nanoparticles. Characterization of the nanoparticles, including dynamic light scattering (DLS) analysis, TEM, and UV/Vis absorption spectroscopy, confirmed their suitability and high stability for passive drug delivery. Antibacterial and antifungal activities were evaluated against a panel of pathogens, revealing significant inhibitory effects on Gram-positive strains; particularly BER, SMA-BER, and NR16 were active against MRSA, MSSA, VR, and VS E. faecalis, and S. epidermidis. Additionally, SMA-BER and SMA-NR16 showed promising activity against biofilm formation of S. epidermidis; while the two free drugs contributed to S. epidermidis biofilm disruption activity. Hemolysis tests and in vitro studies on human embryonic kidney cells (HEK-293) confirmed the safety profiles of the nanoparticles and free drugs. Overall, this research highlighted the potential of nanotechnology in developing effective antibacterial agents with reduced toxicity, addressing the growing threat of MDR bacterial infections.

All trans retinoic acid as a host-directed immunotherapy for tuberculosis

Tuberculosis (TB) is the top bacterial infectious disease killer and one of the top ten causes of death worldwide. The emergence of strains of multiple drug-resistant tuberculosis (MDR-TB) has pushed our available stock of anti-TB agents to the limit of effectiveness. This has increased the urgent need to develop novel treatment strategies using currently available resources. An adjunctive, host-directed therapy (HDT) designed to act on the host, instead of the bacteria, by boosting the host immune response through activation of intracellular pathways could be the answer. The integration of multidisciplinary approaches of repurposing currently FDA-approved drugs, with a targeted drug-delivery platform is a very promising option to reduce the long timeline associated with the approval of new drugs - time that cannot be afforded given the current levels of morbidity and mortality associated with TB infection. The deficiency of vitamin A has been reported to be highly associated with the increased susceptibility of TB. All trans retinoic acid (ATRA), the active metabolite of vitamin A, has proven to be very efficacious against TB both in vitro and in vivo. In this review, we discuss and summarise the importance of vitamin A metabolites in the fight against TB and what is known regarding the molecular mechanisms of ATRA as a host-directed therapy for TB including its effect on macrophages cytokine profile and cellular pathways. Furthermore, we focus on the issues behind why previous clinical trials with vitamin A supplementation have failed, and how these issues might be overcome.

Development of an amphotericin B micellar formulation using cholesterol-conjugated styrene-maleic acid copolymer for enhancement of blood circulation and antifungal selectivity

Amphotericin B (AmB) is an effective antifungal agent for life-threatening systemic fungal infections. However, its poor solubility in water and organic solvents makes it difficult to formulate. We previously reported AmB-encapsulated micellar formations using styrene-maleic acid copolymer (SMA) and butylated SMA. These micelles make AmB water-soluble; however, the blood circulation of AmB by these intravenous administrations was as low as that of Fungizone®, a conventional micellar formulation of AmB. The destabilization of SMA micelles by salt in the blood has been suggested to be a cause of low blood circulation. Therefore, in this study, to reduce salt-induced instability and increase blood circulation of the micelles, we covalently attached cholesterol molecules to the SMA backbone because AmB interacts with sterols. This AmB nanoparticle micellar formulation (Cho-SMA/AmB micelles) was water-soluble, stable in the presence of salts, and formed a complex with albumin. Compared with Fungizone®, this formulation had equal antifungal activity and markedly improved blood circulation and lower toxicity. Its toxicity was further reduced in the presence of albumin. Taken together, our results indicate that Cho-SMA/AmB micelles could be an intravenous formulation with high antifungal selectivity, and drug interactants-conjugated SMA system could be applied to a variety of drug-loaded nanomicellar systems.

[Nanoparticle Formation and Delivery of Poorly Water-soluble Drugs by Hydrophobized Polymers]

When a hydrophobic group is introduced into a water-soluble polymer, self-assembly with the hydrophobic group as nucleus occurs in water. In the 1990s, many researchers focused on this phenomenon and various self-aggregates were prepared. Among them, a block copolymer consisting of a hydrophilic chain and a hydrophobic chain is associated in water, producing polymer micelles with the hydrophilic chain oriented in the outer shell and the hydrophobic chain as core. Meanwhile, many studies were conducted to create polymer self-associates by introducing hydrophobic groups into water-soluble polymers. In this review, the author describes hydrophobized polymers with polysaccharides and synthetic polymers that are frequently used as pharmaceutical raw materials. In addition are outlined the usefulness of hydrophobized polymers as carriers with the function of encapsulating and solubilizing poorly water-soluble drugs, along with the results of our research.

Formulation approaches for improved retinoids delivery in the treatment of several pathologies

Retinoid acid (RA) and other retinoids are extensively used as therapeutic agents in the treatment of several types of cancer and skin disorders. However, the efficiency of these medical agents is compromised due to the unsatisfactory concentration of retinoids in the target cells/tissues. Furthermore, severe side-effects are related to retinoids administration. Incorporation of retinoids into carrier-based delivery systems using encapsulation technology has been proposed in order to overcome the limitations of using free retinoids in the treatment of several pathologies. The present work starts exploring the competences and the difficulties of using retinoids in health care. The metabolism and the main considerations about the mechanism of action of retinoids are also discussed. The final sections are focused on the most recent studies about RA controlled delivery systems to be used in the medical field.