Pharmacokinetic considerations in the treatment of XXXX .

@entity1 @entity32 @entity796 @entity267 @entity1036 @entity2348 @entity794 @entity281 @entity328
The eye is relatively impermeable to micro-organisms and other environmental elements. However, if corneal integrity is breached by trauma, a sight-threatening @entity2348 can result. @entity794 , @entity796 , and @entity328 are the most common bacterial pathogens associated with @entity281 of compromised corneas. Bacterial enzymes and toxins, as well as factors associated with the host immune response, can lead to tissue destruction during @entity281 . For successful therapy, an antibacterial agent must be active against the pathogen and must be able to overcome the permeability barrier of the @entity267 . Topical application of antibacterial agents adequately delivers drugs to the @entity267 . However, drug concentrations at the site of @entity281 are not always sufficient to rapidly kill infective organisms. Infections with antibiotic-resistant strains present an even greater therapeutic challenge. In addition, sterilisation of the @entity267 by antibacterial agents does not eliminate @entity32 and corneal scarring that accompany @entity281 . Steroidal and non-steroidal antiinflammatory agents limit corneal scarring during experimentally induced @entity1036 . However, although promising, concomitant use of these drugs with antibacterial agents remains controversial. Two ocular drug delivery systems that provide high and sustained concentrations of drug to ocular tissues are corneal collagen shields and transcorneal iontophoresis. The collagen shield, originally designed as a bandage lens, prolongs drug contact with the @entity267 . Chemotherapeutic studies of experimental @entity1036 demonstrate that shields hydrated with antibacterial agents reduce bacteria in the @entity267 as well as or better than frequent applications of fortified antibacterial drops. Transcorneal iontophoresis uses an electric current to drive charged drugs into the @entity267 . In experimentally induced @entity1036 , transcorneal iontophoresis of antibacterial agents is superior to topically administered ocular drops for reducing the numbers of bacteria in the @entity267 . Although both drug delivery systems appear to be well tolerated and nontoxic in animal models, clinical trials in @entity1 are required to determine the usefulness of these drug delivery systems in clinical trials. Based on present experimental results, future therapy of @entity1036 will involve efficient drug delivery devices, the use of new antibacterial agents or combinations of presently available antibacterial agents, and careful use of adjuvant anti-inflammatory agents.
