Thiolation of Polymers; A re-oriented approach towards targeted drug delivery

Targeted drug delivery remains a challenge for the pharmaceutical scientists due to less solubility of API and less compatibility and contact time of excipients with mucous membrane. Modification in the composition of excipients by addition of different functional groups can be used to overcome the problems. Addition of thiol group by different methods can increase the mucoadhesion, solubility, stability in acidic medium and contact time of dosage forms. Resulting thiol containing polymers make a disulfide bonds with the mucous membrane. Review contains a brief account on introduction to thiomers, polymers used in thiolation, S-protected preactivated thiomers, dosage forms including micro and nanoparticles, microgels and transdermal patches comprising thiolated polymers and description of different preparatory methods of thiolated polymers. Additionally, the review also focused In-vivo studies performed on mucosal membrane of animals to ensure the improved permeation, efflux pump inhibition and controlled release effect of thiomers.