A spotlight on thiolated natural polymers and their relevance in mucoadhesive drug delivery system

Design and Evaluation of S-Protected Thiolated-Based Itopride Hydrochloride Polymeric Nanocrystals for Functional Dyspepsia: QbD-Driven Optimization, In Situ, In Vitro, and In Vivo Investigation

Mucoadhesive nanosized crystalline aggregates (NCs) can be delivered by the gastrointestinal, nasal, or pulmonary route to improve retention at particular sites. Itopride hydrochloride (ITH) was selected as a drug candidate due to its absorption from the upper gastrointestinal tract. For drug localization and target-specific actions, mucoadhesive polymers are essential. The current work aimed to use second-generation mucoadhesive polymers (i.e., thiolated polymers) to enhance mucoadhesive characteristics. An ITH-NC formulation was enhanced using response surface methodology. Concentrations of Tween 80 and Polyvinyl pyrrolidone (PVP K-30) were selected as independent variables that could optimize the formulation to obtain the desired entrapment efficacy and particle size/diameter. It was found that a formulation prepared using Tween 80 at a concentration of 2.55% and PVP K-30 at 2% could accomplish the goals for which an optimized formulation was needed. Either xanthan gum (XG) or thiolated xanthan gum (TXG) was added to the optimized formulation to determine how they affected the mucoadhesive properties of the formulation. Studies demonstrated that there was an initial burst release of ITH from the ITH/NC/XG and ITH/NC/TXG in the early hours and then a steady release for 24 h. As anticipated, the TXG formulation had a better mucin interaction, and this was needed to ensure that the drug was distributed to tissues that produce mucus. Finally, at the measured concentrations, the ITH/NC showed minimal cytotoxicity against lung cells, indicating that it may have potential for additional in vivo research. The enhanced bioavailability and mean residence time of the designed mucoadhesive NC formulations were confirmed by pharmacokinetic studies.

Compression-coated pulsatile chronomodulated therapeutic system: QbD assisted optimization

Pulsatile drug delivery systems have drawn attention in contemporary research for designing chronotherapeutic systems. The current work aims to design pulsatile ketorolac tromethamine tablets using compression coating for delayed delivery with a lag time suitable for the treatment of morning stiffness in arthritis. Rapidly disintegrating core tablets of ketorolac tromethamine were formulated using super-disintegrants, and the optimized formulation was compression using PEO WSR coagulant and Eudragit RLPO for delaying the release. The central composite design and response surface methodology were employed to optimize the formulation and process parameters namely PEO WSR Coagulant (X₁), Eudragit RLPO (X₂), and Hardness (X₃). The dependent variables optimized were lag time and time required for 95% drug release. Analysis using response surface graphs and mathematical modeling of the results allowed identifying and quantifying the formulation variables active on the selected responses. A polynomial equation fitted to the data was used to predict the composition with optimum responses. Compression-coated pulsatile tablets’ optimized composition exhibited a lag time of 9 h and released 95% of the ketorolac tromethamine in 17.42 h. Validation of the mathematical model assured the reliability of QBD in formulation design. In vivo X-ray imaging and pharmacokinetic studies established a strong relationship between the coated polymers maintaining the desired lag time for delayed delivery of the active to coincide with the chronobiology for enhanced bioavailability at the right time when needed.

Development of Novel Unfolding Film System of Itopride Hydrochloride Using Box-Behnken Design-A Gastro Retentive Approach

Currently, gastro-retentive dosage forms achieved a remarkable position among the oral drug delivery systems. This is a broadly used technique to hold the drug delivery systems for a long duration in the gastro intestine (GI) region, slow drug delivery, and overcome other challenges related to typical oral delivery such as low bioavailability. The current work aimed to formulate and characterize a new expandable gastro-retentive system through Itopride Hydrochloride (IH)’s unfolding process for controlled release. The IH-loaded unfolding film formulation was optimized using the Box-Behnken design for folding endurance and length of tested layer (LTL). Initially, the formulation was made using several anti-adhesive additives to promote the unfolding mechanism. Citric acid and sodium bicarbonate were selected as anti-adhesives based on these results. The enfolded film in a capsule shell was shown to unroll in the stomach fluids and render drug delivery up to 12 h in acidic conditions. A fabricated system should have dimensions more than the size of the relaxed pyloric sphincter, and as required, >20 mm LTL was identified. This further confirms that the residence period in the stomach is irrelevant to the fed or fasted condition. Based on desirability criteria, the formulation containing 143.83, 0.7982, and 14.6096 Eudragit L100, PEG, and sodium bicarbonate are selected as optimized formulations (O-IH-UF). The optimized formulation was further analyzed for various parameters such as tensile strength, mechanical strength, unfolding nature, degradability, and in vitro release studies. The pharmacokinetic study revealed greater AUC (area under the curve) and long half-life with the designed O-IH-UF formulation, confirming that the unfolding film type can be a favorable drug system for enhancing the bioavailability of low soluble drugs. The results showed that unfolding types of gastro retentive systems could potentiate the drugs with stability issues in an alkaline medium or those with absorption in acidic conditions.

Augmentation of Antidiabetic Activity of Glibenclamide Microspheres Using S-Protected Okra Powered by QbD: Scintigraphy and In Vivo Studies

Successful drug delivery by mucoadhesive systems depends on the polymer type, which usually gets adherent on hydration. The intended polymers must sustain the association with biomembranes and preserve or accommodate the drug for an extended time. The majority of hydrophilic polymers tend to make weak interactions like noncovalent bonds, which hampers the positioning of dosage forms at the required target sites, leading to inefficient therapeutic outcomes. It is possible to overcome this by functionalizing the natural polymers with thiol moiety. Further, considering that S-protected thiomers can benefit by improving thiol stability at a broad range of pH and enhancing the residence period at the required target, 2-mercapto-nicotinic acid (MA) was utilized in this present study to shield the free thiol groups on thiolated okra (TO). S-protected TO (STO) was synthesized and characterized for various parameters. Glibenclamide-loaded microspheres were formulated using STO (G-STO-M), and the process was optimized. The optimized formulation has shown complete and controlled release of the loaded drug at the end of the dissolution study. Cell viability assay indicated that the thiolated S-protected polymers gelated very well, and the formulated microspheres were safe. Further, G-STO-M showed considerable in vivo mucoadhesion strength. The glucose tolerance test confirmed the efficacy of STO formulation in minimizing the plasma glucose level. These results favor S-protection as an encouraging tool for improving the absorption of poorly aqueous soluble drugs like glibenclamide.

Mucoadhesive alginate synthesis: a multivariate calibration approach

Alginate–cysteine thiomer were synthesized by a 2-step DoE and PLSR. Processing variables were calibrated in a single PLS model optimizing –SH and –S–S–. The G′/G′′ was 7-fold higher than neat alginate and –SH was 55–120% higher than previous reports.