Search Results (7)

The discovery and development of new pharmaceutical drugs is a costly, time-consuming, and highly manual process, with significant challenges in ensuring drug bioavailability at target sites. Computational techniques are highly employed in drug design, particularly to predict the pharmacokinetic properties of molecules. One major kinetic challenge in central nervous system drug development is the permeation through the blood–brain barrier (BBB). Several different computational techniques are used to evaluate both BBB permeability and target delivery. Methods such as quantitative structure–activity relationships, machine learning models, molecular dynamics simulations, end-point free energy calculations, or transporter models have pros and cons for drug development, all contributing to a better understanding of a specific characteristic. Additionally, the design (assisted or not by computers) of prodrug and nanoparticle-based drug delivery systems can enhance BBB permeability by leveraging enzymatic activation and transporter-mediated uptake. Neuroactive peptide computational development is also a relevant field in drug design, since biopharmaceuticals are on the edge of drug discovery. By integrating these computational and formulation-based strategies, researchers can enhance the rational design of BBB-permeable drugs while minimizing off-target effects. This review is valuable for understanding BBB selectivity principles and the latest in silico and nanotechnological approaches for improving CNS drug delivery. Full article

Quinol derivatives of estrogens are effective pro-drugs in steroid replacement therapy. Here, we report that these compounds can be synthesized in one-pot conditions and high yield by blue LED-driven photo-oxygenation of parent estrogens. The oxidation was performed in buffer and eco-certified 2-methyltetrahydrofuran as the two-liquid-phase reaction solvent, and in the presence of meso-tetraphenyl porphyrin as the photosensitizer. Two steroidal prodrugs 10β, 17β-dihydroxyestra-1,4-dien-3-one (DHED) and 10β-Hydroxyestra-1,4-diene-3,17-dione (HEDD) were obtained with high yield and selectivity. Full article

Beneficial effects of estrogens in the central nervous system (CNS) results from the synergistic combination of their well-orchestrated genomic and non-genomic actions, making them potential broad-spectrum neurotherapeutic agents. However, owing to unwanted peripheral hormonal burdens by any currently known non-invasive drug administrations, the development of estrogens as safe pharmacotherapeutic modalities cannot be realized until they are confined specifically and selectively to the site of action. We have developed small-molecule bioprecursor prodrugs carrying the para-quinol scaffold on the steroidal A-ring that are preferentially metabolized in the CNS to the corresponding estrogens. Here, we give an overview of our discovery of these prodrugs. Selected examples are shown to illustrate that, independently of the route of administrations and duration of treatments, these agents produce high concentration of estrogens only in the CNS without peripheral hormonal liability. 10β,17β-Dihydroxyestra-1,4-dien-3-one (DHED) has been the best-studied representative of this novel type of prodrugs for brain and retina health. Specific applications in preclinical animal models of centrally-regulated and estrogen-responsive human diseases, including neurodegeneration, menopausal symptoms, cognitive decline and depression, are discussed to demonstrate the translational potential of our prodrug approach for CNS-selective and gender-independent estrogen therapy with inherent therapeutic safety. Full article

17β-Estradiol (E2), the main human estrogen, has been known to exert multiple actions throughout the body, including in the central nervous system (CNS). In particular, it has been shown that E2 is gender-independently needed for brain and eye health. Lack of E2 due to normal aging and/or pathological processes leads to neurological and psychiatric diseases as well as accelerated neurodegeneration. Current estrogen replacement therapies, however, cannot be used as therapeutic interventions to treat these maladies due to a profound, unwanted hormonal exposure to the rest of the body. In this presentation, we show that the small-molecule bioprecursor prodrug 10β,17β-dihydroxyestra-1,4-dien-3-one (DHED) produces E2 only in the CNS but remains inert in the rest of the body, both upon chronic systemic and topical administrations, thereby avoiding the detrimental side-effects of the hormone, such as stimulation of the uterus and tumor growth. The highly localized production of E2 in the CNS will be shown through a series of bioanalytical assays and efficacy studies using animal models of estrogen-responsive maladies pertaining to the brain and the retina. Owing to DHED’s significantly more favorable physicochemical properties than the highly lipophilic parent E2 for transport through biological membranes such as the blood-brain barrier or the cornea, a highly effective E2 therapy can be achieved in rodents upon prodrug administration, which further enhances therapeutic safety. Altogether, our patented DHED approach shows unprecedented selectivity to deliver E2 into the CNS and, thus, promises a high translation value in terms of efficacious and safe treatment against neurodegeneration as well as neurological and psychiatric symptoms arising from estrogen deficiency. Full article

Background: The blood brain barrier (BBB) is a dynamic and functional structure which poses a vast challenge in the development of drugs acting on the central nervous system (CNS). While most substances are denied BBB crossing, selective penetration of substances mainly occurs through diffusion, carrier mediated transport, or receptor mediated transcytosis. Methods: Strategies in enhancing BBB penetration have been reviewed and summarized in accordance with their type of formulation. Highlights in monoclonal antibodies, peptide-vectors, nanoparticles, and simple prodrugs were included. Conclusion: Nanoparticles and simple prodrugs, for example, can be used for efficient BBB penetration through inhibition of efflux mechanisms, however, monoclonal antibodies are the most promising strategy in BBB penetration. Close follow-up of future development in this area should confirm our expectation. Full article

Although several viruses can easily infect the central nervous system (CNS), antiviral drugs often show dramatic difficulties in penetrating the brain from the bloodstream since they are substrates of active efflux transporters (AETs). These transporters, located in the physiological barriers between blood and the CNS and in macrophage membranes, are able to recognize their substrates and actively efflux them into the bloodstream. The active transporters currently known to efflux antiviral drugs are P-glycoprotein (ABCB1 or P-gp or MDR1), multidrug resistance-associated proteins (ABCC1 or MRP1, ABCC4 or MRP4, ABCC5 or MRP5), and breast cancer resistance protein (ABCG2 or BCRP). Inhibitors of AETs may be considered, but their co-administration causes serious unwanted effects. Nasal administration of antiviral drugs is therefore proposed in order to overcome the aforementioned problems, but innovative devices, formulations (thermoreversible gels, polymeric micro- and nano-particles, solid lipid microparticles, nanoemulsions), absorption enhancers (chitosan, papaverine), and mucoadhesive agents (chitosan, polyvinilpyrrolidone) are required in order to selectively target the antiviral drugs and, possibly, the AET inhibitors in the CNS. Moreover, several prodrugs of antiretroviral agents can inhibit or elude the AET systems, appearing as interesting substrates for innovative nasal formulations able to target anti-Human Immunodeficiency Virus (HIV) agents into macrophages of the CNS, which are one of the most important HIV Sanctuaries of the body. Full article

This review describes specific strategies for targeting to the central nervoussystem (CNS). Systemically administered drugs can reach the brain by crossing one of twophysiological barriers resistant to free diffusion of most molecules from blood to CNS: theendothelial blood-brain barrier or the epithelial blood-cerebrospinal fluid barrier. Thesetissues constitute both transport and enzymatic barriers. The most common strategy fordesigning effective prodrugs relies on the increase of parent drug lipophilicity. However,increasing lipophilicity without a concomitant increase in rate and selectivity of prodrugbioconversion in the brain will result in failure. In these regards, consideration of theenzymes present in brain tissue and in the barriers is essential for a successful approach.Nasal administration of lipophilic prodrugs can be a promising alternative non-invasiveroute to improve brain targeting of the parent drugs due to fast absorption and rapid onsetof drug action. The carrier-mediated absorption of drugs and prodrugs across epithelial andendothelial barriers is emerging as another novel trend in biotherapeutics. Several specifictransporters have been identified in boundary tissues between blood and CNScompartments. Some of them are involved in the active supply of nutrients and have been used to explore prodrug approaches with improved brain delivery. The feasibility of CNSuptake of appropriately designed prodrugs via these transporters is described in detail. Full article