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Photodynamic Therapy with Blended Conducting Polymer/Fullerene Nanoparticle Photosensitizers
Published on: October 28, 2015
Photosensitizers for photodynamic therapy of cutaneous disease
1Department of Pharmacy, Dermatology Centre, Hope Hospital, Salford, Manchester M6 8HD, UK.
Abstract:
Photodynamic therapy is a rapidly developing treatment modality in dermatology. A sensitizer drug is activated by light in the presence of oxygen. This results in the release of reactive oxygen species that damage the target tissue. The ideal features of a photosensitizer are that it should be highly selective for lesional tissue, activated by light of a sufficiently long wavelength for tissue penetration, and have a high photodynamic yield (i.e. production of singlet oxygen). A short time interval between administration and its maximal accumulation in tumour tissue, followed by rapid tissue clearance, are also desirable. First-generation sensitizers were complex chemical mixtures, needing parenteral administration and causing troublesome and prolonged photosensitivity. A range of second-generation sensitizers of different chemical families show several advantages including purity, longer activation wavelength and less prolonged photosensitivity, but effective topical formulations have not been developed. Currently, the most convenient and widely practised form of PDT for cutaneous disorders is the topical application of the pro-drug delta-aminolevulinic acid or its methylated ester, which are activated by light following metabolism to the endogenous sensitizer protoporphyrin IX.
Insights
Photodynamic therapy (PDT) uses light-activated drugs to destroy diseased cells in dermatology. Newer topical treatments offer improved efficacy and reduced side effects compared to older methods.
Area of Science:
- Dermatology
- Photochemistry
- Oncology
Background:
- Photodynamic therapy (PDT) is an evolving dermatological treatment.
- PDT involves a photosensitizer drug, light, and oxygen to generate reactive oxygen species, damaging target tissues.
- Ideal photosensitizers possess high selectivity, long-wavelength activation for tissue penetration, and high photodynamic yield.
Purpose of the Study:
- To review the development and characteristics of photosensitizers for dermatological PDT.
- To compare first-generation and second-generation photosensitizers.
- To highlight current advancements in topical PDT formulations.
Main Methods:
- Literature review of photosensitizer development in photodynamic therapy.
- Analysis of sensitizer properties including selectivity, wavelength, photodynamic yield, and pharmacokinetics.
- Evaluation of different generations of photosensitizers and their clinical applications.
Main Results:
- First-generation photosensitizers were complex, required parenteral administration, and caused prolonged photosensitivity.
- Second-generation photosensitizers offer advantages like purity and longer wavelengths but lack effective topical formulations.
- Topical delta-aminolevulinic acid (ALA) or its ester is currently the most practical PDT method for skin disorders.
Conclusions:
- Advancements in photosensitizer technology have improved PDT efficacy and safety.
- Topical pro-drugs like ALA represent a convenient and effective approach for dermatological PDT.
- Ongoing research aims to develop improved photosensitizers with enhanced topical delivery and reduced side effects.
