Background: Some kinds of cations and anions are contained in body fluids such as
blood, interstitial fluid, gastrointestinal juice, and tears at relatively high concentration. Ionresponsive
drug delivery is available to design the unique dosage formulations which provide optimized
drug therapy with effective, safe and convenient dosing of drugs.
Objective: The objective of the present review was to collect, summarize, and categorize recent research
findings on ion-responsive drug delivery systems.
Results: Ions in body fluid/formulations caused structural changes of polymers/molecules contained
in the formulations, allow formulations exhibit functions. The polymers/molecules responding to
ions were ion-exchange resins/fibers, anionic or cationic polymers, polymers exhibiting transition at
lower critical solution temperature, self-assemble supramolecular systems, peptides, and metalorganic
frameworks. The functions of ion-responsive drug delivery systems were categorized to controlled
drug release, site-specific drug release, in situ gelation, prolonged retention at the target sites,
and enhancement of drug permeation. Administration of the formulations via oral, ophthalmic, transdermal,
and nasal routes has showed significant advantages in the recent literatures.
Conclusion: Many kinds of drug delivery systems responding to ions have been reported recently
for several administration routes. Improvement and advancement of these systems can maximize
drugs potential and contribute to patients in the world.