The focus of this review is to describe the state-ofart in the development of innovative drug delivery systems for phthalocyanines as photosensitizers for photodynamic therapy (PDT). PDT is a medical treatment combining photosensitizers (PSs) activated by visible light of a specific wavelength to selectively destroy targeted cells, tumor tissues and its surrounding vasculature. In the last decades, PDT has been under intense investigation, first as a promising alternative approach for improved cancer treatment, later against microbial infection and nowadays, mainly in aesthetic medicine, against age-related degeneration. The success of PDT is restricted because of difficulties with administration and skin permeation of PSs. As PDT importance raises, there is high interest for advanced formulations and delivery systems (DDS) for PS, especially formulations based on nanotechnology. Accordingly, this review deals with the innovations pertaining to DDS for PDT as disclosed in recent patents and literature.

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This updated review aims to describe the current status in the development of liposome-based systems for the targeted delivery of phthalocyanines for photodynamic therapy (PDT). Although a number of other drug delivery systems (DDS) can be found in the literature and have been studied for phthalocyanines or similar photosensitizers (PSs), liposomes are by far the closest to clinical practice. PDT itself finds application not only in the selective destruction of tumour tissues or the treatment of microbial infections, but above all in aesthetic medicine. From the point of view of administration, some PSs can advantageously be delivered through the skin, but for phthalocyanines, systemic administration is more suitable. However, systemic administration places higher demands on advanced DDS, active tissue targeting and reduction of side effects. This review focuses on the already described liposomal DDS for phthalocyanines, but also describes examples of DDS used for structurally related PSs, which can be assumed to be applicable to phthalocyanines as well.