Chapter 7: Photosensitizer Delivery for Photodynamic Antimicrobial Chemotherapy

The susceptibility of microorganisms to antimicrobial photodynamic therapy under in vitro and in vivo conditions has been extensively demonstrated. However, for the treatment to be successful in the clinical situation, development of enhanced strategies for delivery of photosensitizers and light to the site of action is required. Due to limited light penetration through tissue, clinical photodynamic antimicrobial chemotherapy (PACT) is limited to areas of the body where light can be delivered relatively easily, such as the skin and body cavities. Factors, such as physicochemical properties of the photosensitizer, photosensitizer dose to be delivered, barrier properties of the target site and patient acceptability all impact upon the method of drug delivery. Many studies to date in the field of PACT employed simplistic methods of drug delivery, with the requirement for more complex, controlled methods of delivery apparent in order to improve treatment outcomes. This chapter provides a comprehensive review of work carried out to date on delivery of photosensitizers for use in PACT, including topical, intranasal and oral/buccal delivery, as well as targeted delivery. It is hoped that, through a rational approach to formulation design and subsequent success in small-scale clinical trials, more widespread use will be made of PACT in the clinic, to the benefit of patients worldwide.