title: Successful cutaneous delivery of the photosensitizer silicon phthalocyanine 4 for photodynamic therapy.
abstract: BACKGROUND
  Photodynamic therapy (PDT) has been shown to be effective in the treatment of malignancies of a variety of organ systems, including the lungs, bladder, gastrointestinal tract and skin. Cutaneous lesions serve as ideal targets of PDT because of the accessibility of the skin to light. To achieve optimum results, the photosensitizer must be delivered effectively into the target layers of the skin within a practical timeframe, via noninvasive methods.
  
  
  OBJECTIVE
  To determine whether topical application of a second-generation photosensitizer, silicon phthalocyanine (Pc) 4 [SiPc(OSi(CH3)2 (CH2)3 N(CH3)2)(OH)], results in effective penetration of the skin barrier.
  
  
  METHODS
  Penetration of Pc 4 was evaluated using standard Franz-type vertical diffusion cell experiments on surrogate materials (silicone membranes) and laser-scanning confocal microscopy of normal skin biopsy samples from human volunteers.
  
  
  RESULTS
  The Franz diffusion data indicate that Pc 4 formulated in an ethanol/propylene glycol solution (70/30%, v/v) can penetrate the membrane at a flux that is appreciable and relatively invariant. Using the same formulation, Pc 4 uptake could be detected in human skin via laser-scanning confocal microscopy.
  
  
  CONCLUSIONS
  After topical application, Pc 4 is absorbed into the epidermis in as little as 1 h, and the absorption increased with increasing time and dose. Pc 4 can be effectively delivered into human skin via topical application. The data also suggest that the degree of penetration is time- and dose-dependent.
authors.affiliation: Department of Dermatology, Case Western Reserve University/University Hospitals Case Medical Center, Cleveland, OH 44106-4926, USA.
authors.forename: M
authors.initials: M
authors.lastname: Lam
authors.forename: A H
authors.initials: AH
authors.lastname: Hsia
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: M
authors.initials: M
authors.lastname: Guo
authors.forename: A R
authors.initials: AR
authors.lastname: Swick
authors.forename: J C
authors.initials: JC
authors.lastname: Berlin
authors.forename: T S
authors.initials: TS
authors.lastname: McCormick
authors.forename: M E
authors.initials: ME
authors.lastname: Kenney
authors.forename: N L
authors.initials: NL
authors.lastname: Oleinick
authors.forename: K D
authors.initials: KD
authors.lastname: Cooper
authors.forename: E D
authors.initials: ED
authors.lastname: Baron
mesh_terms: D000287:Administration, Topical; D000328:Adult; D015194:Diffusion Chambers, Culture; D005260:Female; D006801:Humans; D007211:Indoles / Q000493:pharmacokinetics*; D008297:Male; D008567:Membranes, Artificial; D018613:Microscopy, Confocal; D017646:Organosilicon Compounds / Q000493:pharmacokinetics*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000493:pharmacokinetics*; D012867:Skin / Q000378:metabolism*; D055815:Young Adult
chemical_list: D007211:Indoles; D008567:Membranes, Artificial; D017646:Organosilicon Compounds; D017319:Photosensitizing Agents; C082854:silicon phthalocyanine