Hydrogels for delivery of bioactive agents: A historical perspective

Abstract

Since 1960 when the history of modern hydrogels began significant progresses have been made in the field of controlled drug delivery. In particular, recent advances in the so-called smart hydrogels have made it possible to design highly sophisticated formulations, e.g., self-regulated drug delivery systems. Despite intensive efforts, clinical applications of smart hydrogels have been limited. Smart hydrogels need to be even smarter to execute functions necessary for achieving desired clinical functions. It is necessary to develop novel hydrogels that meet the requirements of the intended, specific applications, rather than finding applications of newly developed hydrogels. Furthermore, developing smarter hydrogels that can mimic natural systems is necessary, but the fundamental differences between natural and synthetic systems need to be understood. Such understanding will allow us to develop novel hydrogels with new, multiple functions we are looking for.

Hydrogels based on N-isopropylmethacrylamide and N-isopropylacrylamide

“…They are also called 'smart' networks and are the subject of scienitific research because of the potential for high-tech application in the field of biomedicine, pharmacy, biotechnology, bioseparation, biosensors, agriculture and cosmetics. The history of smart hydrogels dates back to 1960 [4]. Smart hydrogels exhibit significant physical and chemical changes in response to slight changes in their environment [5].…”

Deswelling of Hydrogels in Aqueous and Polyethylene Glycol Solutions. A New Approach for Drug Delivery Application

“…Hydrogels, which are a family relatively recent and important of polymers, have an extensive interest in many domains shown by the increasing number of publications [1,2]. It can be defined as polymers that capable of absorbing water and biological fluid without changing their forms [3,4].…”

Synergistic effect of poly(acrylamide)-incorporated poly(L-ascorbic acid) hydrogels in controlled release and wound dressings

“…[13][14][15] More specifically, ionic hydrogels are used to immobilize a drug delivery device on a specific site for targeted release and optimal drug delivery due to the intimacy and extended duration of contact. [2][3][4][5][6] After intimate contact is established, the rate and duration of drug release depends on the swelling behavior of the hydrogel. [1,7] The usual duration of treatment for fungal or yeast skin infection has been 2-4 weeks (topical therapy) or 3-6 weeks (oral therapy) but shorter courses of topical terbinafine hydrochloride (TER-HCl) (1-2 weeks) were as effective as standard duration therapy in dermatomycose.…”

“…[1] Hydrogels are used extensively in medicine and pharmacy as contact lenses, artificial disk, catheters, biosensors, drug delivery system, wound dressings, etc. [2] It could be outlined the performance parameters of an "ideal wound dressing" in the following: (i) absorb exudates and toxic components from the wounds surface; (ii) maintain a high humidity at the wound/dressing interface; (iii) allow gaseous exchange; (iv) provide thermal insulation; (v) protect the wound from bacterial penetration; (vi) be nontoxic; and (vii) be removed easily without trauma to the wound. [3] Criteria that were added later included that the material should; (viii) have acceptable handling qualities (resistance to tear and disintegration either wet or dry); and (ix) be conformable and be sterilizable.…”