Background: Mucoadhesive polymers represent a major part of site-specific and localized retention strategies in oral drug delivery. Present research was designed to synthesize and characterize a novel mucoadhesive carbohydrate polymer (thiolated gum ghatti; TGG) which was further employed to fabricate mucoadhesive tablets of domperidone using an industrially viable compression coating technique. Methods: Thiolation of gum ghatti was achieved by the ester formation (esterification) between hydroxyl group and carboxyl group of gum ghatti and thioglycolic acid. Results: TGG was characterized by various physico-chemical techniques such as FTIR, XRD, SEM and DSC techniques. In rheological studies, the observed viscosities of pure gum-mucin were 45.45 and 71.75 mPas and that of thiolated gum were 78.7 and 112.58 mPas respectively in water and simulated gastric fluid. Signifi-cant increase in viscosity for thiolated gum may be attributed to increased macromolecular interactions responsible for enhanced mucoadhesive potential of thiolated gum. In-silico studies corroborate the role of mucin gum interaction and energetic stabilization for en-hanced mucoadhesion properties of thiolated gum. Ex-vivo mucoadhesion strength of gum ghatti and thiolated gum ghatti coated tablets was found to be ranging between 4.67± 0.79 to 8.99± 0.75 g and 11.76± 1.34 to 18.83± 2.07 g respectively. Conclusion: Thiolated gum ghatti may be regarded as a promising polymer for developing different mucoadhesive drug delivery systems.

Drug delivery to the brain represents a challenge especially in the therapy of central nervous system malignancies. Simvastatin (SVT), as other statins, has shown potential anticancer properties that are difficult to exploit in the CNS. In the present work the physico-chemical, mucoadhesive and permeability enhancing properties of simvastatin-loaded poly-ε-caprolactone nanocapsules coated with chitosan for nose-to-brain administration were investigated. Lipid-core nanocapsules coated with different molecular weight (MW) chitosans (LNCchit) prepared by a novel one-pot technique were characterized for particle size, surface charge, particle number density, morphology, drug encapsulation efficiency, interaction between surface nanocapsules with mucin, drug release and permeability across two nasal mucosa models. Results show that all formulations present adequate particle size (below 220 nm), positive surface charge, narrow droplet size distribution (PDI<0.2) and high encapsulation efficiency. Nanocapsules presented controlled drug release and mucoadhesive properties dependent on the MW of the coating chitosan. The results of permeation across RPMI 2650 human nasal cell line evidenced that LNCchit increased the permeation of SVT. In particular, the amount of SVT permeated after 4h for nanocapsules coated with low MW chitosan, high MW chitosan and control SVT was 13.91 ± 0.78 µg, 9.15 ± 1.23 µg and 1.42 ± 0.21 µg respectively. These results were confirmed by the SVT ex vivo permeation across rabbit nasal mucosa. This study highlighted the suitability of LNCchit as promising strategy for the administration of simvastatin for a nose-to-brain approach for the therapy of brain tumors.

The human respiratory syncytial virus (hRSV) poses a serious risk to global public health and is a significant cause of severe lower respiratory infections. There are currently only a few therapies available to treat RSV infections, as well as no RSV vaccinations. Therefore, there is an urgent demand for clinically feasible, safe, and affordable RSV prevention and treatment alternatives. In this study, an ion-activated in situ gel comprising broad-spectrum antiviral 18β-glycyrrhetinic acid (GA) for antiviral action on RSV was developed. In this content, mechanical properties, sprayability, drug content, pH, ex vivo mucoadhesive strength, in vitro drug release pattern, and stability were all examined. Rheological properties were also tested by utilizing in vitro gelation capacity and rheological synergism tests. Finally, the optimized in situ gel's cytotoxic and antiviral activities on RSV cultured in human laryngeal epidermoid carcinoma (HEP-2) cell line were evaluated. In conclusion, the optimized in situ gel prepared with a combination of 0.5%w/w gellan gum and 0.5%w/w sodium carboxymethylcellulose demonstrated good gelation capacity and sprayability (weight deviation between T0 and T14: 0.34%), desired rheological synergism (mucoadhesive force (Fb): 9.53), mechanical characteristics (adhesiveness: 0.300 mJ ± 0.05), ex vivo bioadhesion force (19.67 g ± 1.90), drug content uniformity (RSD%: 0.494), and sustained drug release over period of 168 h (101.57% ± 0.53). The antiviral activity test results showed that the optimized in situ gel had strong anti-HRSV activity (EC50 simultaneous = 0.05 µg/ml, SI = 306; EC50 preinfection = 0.154 µg/ml, SI= 100) which was significantly higher than that of ribavirin (EC50 =4.189 µg/ml; SI= 28) used as a positive control against hRSV. In conclusion, this research has demonstrated the formulation of an effective antiviral nasal spray that has the ability to possess both prophylactic and virucidal activity.

In the field of nasal delivery, one of the most fascinating applications is the delivery of drugs directly to the central nervous system bypassing the blood brain barrier. This approach would provide a series of benefits, such as dose lowering and direct targeting of potent drugs, ultimately reducing their systemic side effects. Recently, clinical trials have explored the nasal administration of insulin for the treatment of Alzheimer’s disease, with promising results. The use of nanomedicines could provide further options for making nose-to-brain delivery reality. In particular, apart from the selection of devices able to deposit the formulation in the upper part of the nose, surface modification of these nanomedicines appears the key strategy to optimize the delivery of drugs from the nasal cavity to the brain. In this review, nanomedicines delivery approaches based on surface electrostatic charges, mucoadhesive polymers, as well as chemical moieties targeting nasal epithelium, will be discussed and critically evaluated for nose-to-brain delivery.

Engineering of drug nanocarriers combining fine-tuned mucoadhesive/mucopenetrating properties is currently being investigated to ensure more efficient mucosal drug delivery. Aiming to improve the transmucosal delivery of hydrophobic drugs, we designed a novel kind nanogel produced by the self-assembly of amphiphilic chitosan graft copolymers ionotropically crosslinked with sodium tripolyphosphate. In this work, we synthesized for the first time chitosan-g-poly(methyl methacrylate) nanoparticles thiolated by the conjugation of N-acetyl cysteine. First, we confirmed that both non-crosslinked and crosslinked nanoparticles in the 0.05-0.1% w/v concentration range display very good cell compatibility in two cell lines that are relevant to oral delivery, Caco2 cells that mimic the intestinal epithelium and HT29-MTX cells that produce mucin. Then, we evaluated the effect of crosslinking, nanoparticle concentration and thiolation on the permeability in vitro utilizing monolayers of (i) Caco2 and (ii) Caco2:HT29-MTX cells (9:1 cell number ratio). Results confirmed that the ability of the nanoparticles to cross Caco2 monolayer was affected by the crosslinking. In addition, thiolated nanoparticles interact more strongly with mucin, resulting in a decrease of the apparent permeability coefficient (Papp) compared to the pristine nanoparticles. Moreover, for all the nanoparticles, higher concentration resulted in lower Papp suggesting indicating that the transport pathways could undergo saturation.