Improving the physicochemical properties of bicalutamide by complex formation with bovine serum albumin

Development, in vitro and ex vivo characterization of lamotrigine-loaded bovine serum albumin nanoparticles using QbD approach

The present study aimed to prepare and optimize lamotrigine-loaded bovine serum albumin nanoparticles (LAM-NP) using the Quality by Design (QbD) approach and to investigate both the in vitro and ex vivo effects of different cross-linking agents glutaraldehyde (GLUT), glucose (GLUC) and 1-(3-dimethylaminutesopropyl)-3-ethylcarbodiimide hydrochloride (EDC) on intranasal applicability. Cross-linked LAM-NP from EDC (NP-EDC-1) showed the lowest Z-average value (163.7 ± 1.9 nm) and drug encapsulation efficacy (EE%) of 97.31 ± 0.17%. The drug release of GLUC cross-linked LAM-NP (NP-GLUC-9), glutaraldehyde cross-linked LAM-NP (NP-GLUT-2), and NP-EDC-1 at blood circulation conditions was higher than the initial LAM. The results of the blood-brain barrier parallel artificial membrane permeability assay (BBB-PAMPA) showed an increase in the permeability of LAM through the BBB with NP-GLUC-9 and an increase in flux with all selected formulations. The ex vivo study showed that LAM diffusion from the selected formulations through the human nasal mucosa was higher than in case of initial LAM. The cytotoxicity study indicated that BSA-NP reduced LAM toxicity, and GLUC 9 mM and EDC 1 mg could be alternative cross-linking agents to avoid GLUT 2% v/v toxicity. Furthermore, permeability through Caco-2 cells showed that nasal epithelial transport/absorption of LAM was improved by using BSA-NPs. The use of BSA-NP may be a promising approach to enhance the solubility, permeability through BBB and decrease the frequency of dosing and adverse effects of LAM.

Monophasic coamorphous sulpiride: a leap in physicochemical attributes and dual inhibition of GlyT1 and P-glycoprotein, supported by experimental and computational insights

Study aimed to design and development of a supramolecular formulation of sulpiride (SUL) to enhance its solubility, dissolution and permeability by targeting a novel GlyT1 inhibition mechanism. SUL is commonly used to treat gastric and duodenal ulcers, migraine, anti-emetic, anti-depressive and anti-dyspeptic conditions. Additionally, Naringin (NARI) was incorporated as a co-former to enhance the drug's intestinal permeability by targeting P-glycoprotein (P-gp) efflux inhibition. NARI, a flavonoid has diverse biological activities, including anti-apoptotic, anti-oxidant, and anti-inflammatory properties. This study aims to design and develop a supramolecular formulation of SUL with NARI to enhance its solubility, dissolution, and permeability by targeting a novel GlyT1 inhibition mechanism, extensive experimental characterization was performed using solid-state experimental techniques in conjunction with a computational approach. This approach included quantum mechanics-based molecular dynamics (MD) simulation and density functional theory (DFT) studies to investigate intermolecular interactions, phase transformation and various electronic structure-based properties. The findings of the miscibility study, radial distribution function (RDF) analysis, quantitative simulations of hydrogen/π-π bond interactions and geometry optimization aided in comprehending the coamorphization aspects of SUL-NARI Supramolecular systems. Molecular docking and MD simulation were performed for detailed binding affinity assessment and target validation. The solubility, dissolution and ex-vivo permeability studies demonstrated significant improvements with 31.88-fold, 9.13-fold and 1.83-fold increments, respectively. Furthermore, biological assessments revealed superior neuroprotective effects in the SUL-NARI coamorphous system compared to pure SUL. In conclusion, this study highlights the advantages of a drug-nutraceutical supramolecular formulation for improving the solubility and permeability of SUL, targeting novel schizophrenia treatment approaches through combined computational and experimental analyses.

Ligand binding to proteins - When flawed fluorescence quenching methodology and interpretation become the new norm

Intrinsic protein fluorescence quenching measurements have become a widespread methodology to determine ligand-binding properties of in particular serum albumin. Particularly common is the use of double log equations to extract parameters like binding constant and stoichiometry and/or number of binding sites. In this article we discuss that the methodology has several significant and often unrecognized pitfalls, and the double log equations are improperly derived for their purported use. Using simulations, it is shown that the binding stoichiometry and binding constants obtained using these equations may differ substantially from their true values. In addition, it is illustrated how this methodology, via the use of site markers, is unsuited to determine the binding site of ligands on serum albumin. We thus call for a reassessment of the literature in which this methodology plays a central role in characterizing ligand binding to proteins.

Association mechanism of bicalutamide and human serum albumin for potential clinical implications

The binding mechanism of molecular interaction between bicalutamide and human serum albumin (HSA) in a pH 7.4 phosphate buffer was studied using various spectroscopic techniques in combination with molecular modeling. Fluorescence data revealed that the fluorescence quenching of HSA by bicalutamide was a static quenching procedure. The binding constants and number of binding sites were evaluated at different temperatures. The thermodynamic parameters, ΔH and ΔS, were calculated to be 4.30 × 104 J·mol-1 and 245 J·mol-1·K-1, respectively, suggesting that the binding of bicalutamide to HSA was driven mainly by hydrophobic interactions and hydrogen bonds. The displacement studies indicated neither Sudlow's site I nor II but subdomain IB as the main binding site for bicalutamide on HSA. The binding distance between bicalutamide and HSA was determined to be 3.54 nm based on the Förster theory. Analysis of circular dichroism, synchronous, and 3D fluorescence spectra demonstrated that HSA conformation was slightly altered in the presence of bicalutamide.

In situ hydrogelation of bicalutamide-peptide conjugates at prostate tissue for smart drug release based on pH and enzymatic activity

Tissue-specific self-assemblies of supramolecular hydrogels have attracted great interest in material design and biomedical applications, for in situ-formed hydrogels serve as an excellent local depot with tunable release of drug therapeutics. Here we report the design and syntheses of a novel class of histidine-containing hexapeptide derivatives (Nap-1 and ID-1) for in situ hydrogelation at the zinc ion-rich prostate tissue. Thanks to the efficient co-ordination between zinc and histidine, both Nap-1 and ID-1 displayed excellent self-assembly capability with a high sensitivity to zinc ions at ∼0.1 equivalency. To foster a prostate-specific drug delivery system (DDS), ID-1 was chosen for further conjugation with bicalutamide (BLT), a clinically used drug for prostate cancer. The as-synthesized ID-1-BLT retained the self-assembly capability with zinc ions, and conferred supramoelcular hydrogels at the prostate site. Interestingly, ID-1-BLT hydrogels demonstrated tunable drug release profiles in a typical tumor microenvironment, with acidic pH and esterase activity regulating the drug release in a dose dependent manner. Consequently, the hydrogel-based DDS demonstrated enhanced potency and selective cytotoxicity against prostate cancer cell DU145 over normal fibroblast cell NIH3T3, plausibly due to differential cellular uptake of drugs as well as the elevated esterase activities in cancer cells. Finally, the biocompatible hydrogel system demonstrated sustained delivery of drugs at the prostate gland of rats, with a superior in situ drug distribution profile compared to that of aqueous solution of BLT alone.