Chapter 11 - Hydrogels as intrinsic antimicrobials
Hydrogels are currently applied as the vehicles for drugs or active substances, rather than the active contributors to therapeutic activities. With increasing challenges related to antimicrobial resistance against many antibiotics, natural origin hydrogels have become attractive as more than just vehicles. Although many natural polymers exhibit intrinsic antimicrobial properties, these properties have not yet been fully exploited. This chapter provides an overview of hydrogels prepared from natural origins with intrinsic antimicrobial properties. The hydrogels are summarized as (1) vehicles for active substances (active substances-in-hydrogels) or as (2) vehicles for delivery systems for active substances (active substances-in-delivery system-in-hydrogels). Both types of formulation offer synergistic activities of both drug/active substances and hydrogel, often covering broader antimicrobial spectra and means to combat antimicrobial resistance. The focus is put on the hydrogels for therapy of skin and vaginal infections, however some other administrations sites are included. The factors affecting the antimicrobial activity of hydrogels are discussed in more detail. The toxicity, potential local irritation, as well as stability issues of novel hydrogels are given the required attention. Perspectives on wider use of hydrogels as active pharmaceutical ingredients are proposed.