Optimization and Pharmacokinetic Evaluation of Gastroretentive Mucoadhesive Microspheres of Propranolol Hydrochloride using Thiolated Tragacanth: A Novel Strategy forEnhanced Drug Delivery
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Abstract
Background: Gastroretentive mucoadhesive drug delivery systems offer a promising approach to enhance the
therapeutic efficacy of drugs with low bioavailability and short half-lives. The current study aims to the formulation
and pharmacokinetic evaluation of propranolol hydrochloride-loaded gastroretentive mucoadhesive microspheres
using thiolated tragacanth (TTG) – a chemically modified natural polymer with improved mucoadhesive capacity.
Materials and Methods: TTG was prepared by esterification and characterized for thiol content, swelling
ability, and mucoadhesive properties. Propranolol hydrochloride-loaded microspheres were prepared employing
ionic gelation with cross-linking using calcium chloride and barium chloride. The prepared microspheres were
characterized for particle size, drug entrapment efficacy, swelling index, and in vitro drug release profiles.
A pharmacokinetic profile in Wistar rats was done to identify increases in bioavailability. Results: Thiolation of the
polysaccharide resulted in 3.5-fold greater thiol levels, greatly improving the mucoadhesive character of tragacant.
Optimum microspheres were spherically shaped with excellent entrapment efficacy of 84.2 ± 2.7%. Release studies
conducted under in vitro conditions indicated controlled drug release over a period of 12 h following Korsmeyer–
Peppas model, indicative of non-Fickian or anomalous diffusion. Pharmacokinetic evaluation showed a 2.8-fold
relative bioavailability increase over the standard propranolol solution, with delayed Tmax and increased Cmax
values, indicating improved systemic absorption. Conclusion: The TTG-based gastroretentive microspheres
developed in this work showed enhanced drug retention and bioavailability, indicating their potential as a new drug
delivery system for propranolol hydrochloride. This work highlights the promise of thiolated natural polymers in
sustained drug delivery systems and invites further research in this direction.
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