Adverse effects associated with photodynamic therapy (PDT) of port-wine stain (PWS) birthmarks.

BACKGROUND: Several Chinese studies suggest that Hemoporfin-mediated photodynamic therapy (PDT) is an alternative treatment for port-wine stain (PWS) birthmarks. OBJECTIVE: To evaluate treatment responses and adverse effects associated with Hemoporfin PDT for the treatment of PWS and their management. METHOD: The medical records of 700 patients who underwent PDT treatment in our center were retrospectively examined. Treatment-related reactions and adverse effects were reviewed. RESULT: Different types of PWS lesions and different individuals showed different immediate responses (e.g. swelling, color change, pain). To certain extents these reactions were a useful indicator of the treatment endpoint. Edema and scabbing were the most common post-treatment responses. Short-term (e.g. blister, eczematous dermatitis, cutaneous photosensitivity) and long-term (e.g. pigmentation change, scar formation) adverse effects were generally caused by the phototoxicity associated with the combination of photosensitizer and light exposure. CONCLUSION: Although PDT is a safe treatment alternative for PWS birthmarks, treatment parameters must be selected for each individual patient and cutaneous changes must be monitored during light irradiation to minimize the risk of adverse effects. Over estimation of required light dosage or failure to recognize cutaneous changes associated with adverse effects can increase the risk of a poor outcome.

Research progress of Hemoporfin--part one: preclinical study.

The second generation photosensitizer Hemoporfin (7(12)-(1-methoxyethyl) -12(7)-(1-hydroxyethyl)-3,8,13,17-tetramethyl-21H,23H-porphin-2,18-dipropionic acid) is a porphyrin derivative which processes a stable structure, high singlet oxygen yield, high photoactivity, low dark toxicity and fast clearance rate. Hemoporfin, also known as hematoporphyrin monomethyl ether (HMME) has been studied and used in photodynamic therapy (PDT) in China since 1989. This series of reports will provide an overview on the preclinical and clinical studies of this PDT photosensitizer. The first part of this series will highlight the results of preclinical studies that focused on the compound's optical characteristics, mechanism of the activities, pharmacological and toxicological properties.

meso-Tetra(hydroxyphenyl)porphyrins, a new class of potent tumour photosensitisers with favourable selectivity.

We compared para-, meta- and ortho-isomers of meso-tetra(hydroxyphenyl)porphyrin (p-, m- and o-THPP) and the potassium salt of the para compound (K-p-THPP) with haematoporphyrin derivative (HpD) and Photofrin II in their ability to sensitise tumours, skin and brain to light. HpD and Photofrin II induced modest tumour photosensitisation at the cost of substantial skin and brain sensitisation. At doses low enough to keep sensitisation of these normal tissues within acceptable limits, tumour sensitisation was sufficient to give necrosis only approximately 2 mm deep after exposure to 10 J cm-2 light. In contrast, doses of p-THPP, K-p-THPP and m-THPP that produced skin and brain sensitivity within acceptable limits sensitised tumours enough to give 4-9 mm necrosis after 10 J cm-2 light. m-THPP was, on a molar basis, about 25-30 times as potent as HpD and Photofrin II in sensitising tumours. o-THPP was also a potent tumour photosensitiser, but induced a prohibitive degree of skin photosensitivity even at low doses. It is unlikely that these differences in relative selectivity are due to differences in such photophysical parameters as optimum activating wavelength (which would affect tissue penetration by light), or light absorption, and physicochemical factors that determine tissue localisation may be involved. The high tumour sensitising potency and favourable tissue selectivity of m-THPP, p-THPP and K-p-THPP make them promising candidates for clinical tumour phototherapy.

[Problems posed by the therapeutic use of photosensitizers in dermatology]. / Problèmes posés par l'utilisation thérapeutique des photosensibilisateurs en dermatologie.

Three phototherapeutic regimens with photosensitization are now used in dermatology: PUVA (psoralen + UVA), TUV (crude coaltar + UV), PRT (phototherapy with hematoporphyrin derivative). The efficiency of PUVA and TUV is well known in several dermatoses. PRT is now being tested experimentally. For TUV, the lack of a standardized regimen does not allow a clear-cut evaluation of the therapy. For PUVA, late side-effects, particularly carcinogenicity have to be considered. To improve efficiency and minimize the side-effects of PUVA some procedures, such as association with retinoïds, pharmaco-kinetic studies for individual adaptation of the therapeutic regimen and the use of new less mutagenic psoralens are helpful. The persistent phototoxicity following treatments with hematoporphyrin derivative constitutes the major side-effect observed, for this phototherapy.

Development of a protocol for photoradiation therapy of malignant brain tumors: part 1. Photosensitization of normal brain tissue with hematoporphyrin derivative.

The successful application of phototherapy to subcutaneous tumors has suggested that a similar procedure should be developed for treating gliomas. As a result, attempts are being made to determine a set of conditions that would optimize the destruction of tumor cells while minimizing injury to surrounding brain tissue. To initiate this task, we developed a novel assay method to assess the amount of phototoxicity induced in normal brain by light exposure of mice treated with hematoporphyrin derivative (HPD). The application of this procedure demonstrated that a sufficient amount of HPD was retained in brain tissue, even 72 hours after injection, to cause severe cerebral damage in light-treated mice.