Photoactivation of endogenous porphyrins for treatment of psoriasis

• US 6,269,818 B1
• Filed: 05/26/1998
• Issued: 08/07/2001
• Est. Priority Date: 05/27/1997
• Status: Expired due to Fees

• Current Assignee: University of British Columbia
• Original Assignee: University of British Columbia
• Inventors: Bissonnette, Robert, Zeng, Haishan, Macaulay, Calum, Lui, Harvey, McLean, David I.
• Primary Examiner(s): Peffley, Michael
• Assistant Examiner(s): Kearney, R.
• Application Number:
  US09/084,865
• Time in Patent Office: 1,169 Days
• Field of Search: 606/1, 606/3, 606/9, 606/10, 606/11, 606/12, 606/14, 606/16, 606/17, 607/88, 607/89, 128/898
• US Class Current: 128/898
• CPC Class Codes: A61K 41/0071 PDT with porphyrins having exactly 20 ring atoms, i.e. based on the non-expanded tetrapyrrolic ring system, e.g. bacteriochlorin, chlorin-e6, or phthalocyanines
• CPC Class Codes: A61K 49/0017 Fluorescence in vivo
• CPC Class Codes: A61K 49/0036 Porphyrins used in photodynamic therapy A61K41/0071 or A61K41/0076; used as targeting group or modifying agent for targeting a therapeutic compound A61K47/546
• CPC Class Codes: A61N 5/062 Photodynamic therapy, i.e. excitation of an agent

Abstract

In one aspect, the invention provides a diagnostic method for identifying psoriatic plaques in which Porphyrins, particularly protoporphyrin IX, are elevated as compared to normal skin and skin of patients with other dermatological diseases, including other forms of psoriatic plaque. Psoriatic plaques with elevated porphyrin levels may be detected by fluorescence and spectral analysis. Endogenous porphyrins in psoriatic plaques may be activated with visible light to treat psoriatic plaques having elevated porphyrin concentrations. Skin conditions may be optimized to increase the endogenous concentration of porphyrins in psoriatic plaques. A topical formulation may be applied to psoriatic plaques to optimize skin conditions such as pH, iron concentration, temperature, hydration, calcium concentration, oxygenation, electrical conductivity and estrogen concentration to increase the concentration of endogenous porphyrins.

Claims

1. A method of treating psoriasis comprising:

a. identifying a psoriatic plaque with elevated endogenous porphyrin levels;

b. treating the psoriatic plaque with visible light.

2. The method of claim 1, wherein the step of identifying the psoriatic plaque comprises illuminating the plaque with excitatory light and detecting autofluorecent light from the plaque.

3. The method of claim 2, wherein the autofluorescent light comprises red light.

4. The method of claim 2 further comprising spectrophotometric analysis of the autofluorescent light to detect a fluorescent emission peak of a porphyrin.

5. The method of claim 4 wherein the fluorescent emission peak is at about 630-635 nm.

6. The method of claim 1 wherein the visible light comprises blue light.

7. The method of claim 2 wherein the visible light comprises blue light.

8. The method of claim 6 wherein the visible light comprises light having a wavelength longer than about 400 nm.

9. The method of claim 2 wherein the excitatory light comprises light having a wavelength between about 320 nm and about 500 nm.

10. The method of claim 9 wherein the excitatory light comprises light having a wavelength between about 400 nm and 500 nm.

11. The method of claim 1 further comprising elevating endogenous porphyrin levels in the psoriatic plaque by buffering the pH in the plaque.

12. The method of claim 11 further comprising administering a topical composition to the plaque which buffers the pH of at least a portion of the plaque at a pH of about 5.7 to about 6.5.

13. The method of claim 1 further comprising the step of administering a topical composition comprising an iron chelator to the plaque.

14. The method of claim 13 wherein the iron chelator is selected from the group consisting of CP94, EDTA and desferrioxamine.

15. A diagnostic method for identifying a psoriatic plaque susceptible to treatment with visible light and having an elevated porphyrin level, comprising illuminating the plaque with excitatory light and detecting autofluorescent light from the plaque.

16. The diagnostic method of claim 15, wherein the autofluorescent light comprises red light.

17. The method of claim 15 further comprising spectrophotometric analysis of the autofluorescent light to detect a fluorescent emission peak at about 630 nm to about 635 nm.

18. The method of claim 15 wherein the visible light comprises light having a wavelength longer than about 400 nm.

19. The method of claim 15 wherein the excitatory light comprises light having a wavelength longer than about 400 nm and about 500 nm.