Photodynamic Therapy

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Photodynamic Therapy by Mind Map: Photodynamic Therapy

1. Mechanism of Action

1.1. Exogenous ALA Applicaion

1.2. Incubation (Metabolism & Accumulation)

1.2.1. Metabolism Exogenous ALA Heme synthesis

1.2.2. Accumulation Porphyrin levels peak in 12 hours Optimal Incubation time for Acne treatment? 3 hours

1.3. Light Exposure

1.3.1. ALA Porphyrins (Ground Energy State) Porphyrins (Excited Energy State)

1.4. Photobleaching

1.4.1. Irreversible oxidation of porphyrins

1.4.2. Starts at the onset of light exposure

1.5. Metabolism and Re-accumulation of Porphyrins

1.5.1. Occurs after therapeutic light exposure is completed

1.5.2. Instruct patients to have strict photoprotection for? 48 hours

2. Porphyrins

2.1. ALA itself is not a photosensitizer

2.2. Accumulation of Protoporphyrin IX depends on?

2.2.1. Cytoplasmic ALA concentration

2.2.2. Expression and Activity of heme-synthesis enzymes (e.g., Porphyrias)

2.2.3. Peripheral Benzodiazapine Receptors PBRs are overexpressed in neoplastic cells, enhancing ALA-PDT efficacy in cancer treatment

2.2.4. Iron Stores

2.3. Peripheral Benzodiazapine Receptors are overexpressed in cancers

2.3.1. PBRs are overexpressed in neoplastic cells, enhancing ALA-PDT efficacy in cancer treatment

3. Light Sources

3.1. Porphyrin Absorption Spectrum (300-650 nm)

3.1.1. Blue Light

3.1.2. Green Light KTP, Nd:YAG

3.1.3. Yellow Light PDL (e.g., LP-PDL 595 nm)

3.1.4. Red Light

3.1.5. IPL

4. Indications

4.1. FDA Approved

4.1.1. Compounds Methyl Aminolevulinate (MAL) 5 Aminolevulinate (ALA)

4.1.2. Actinic Keratoses

4.1.3. Pregnancy Category: C

4.1.4. Not approved for children

4.2. Off-Label

4.2.1. Acne Vulgaris UV light is not therapeutic Blue Light is antiinflammatory Red light alone is not therapeutic Glass-filtered sunlight may be helpful (UVA) Propionibacterium acnes Coproporphyrin III Protoporphyrin IX Mechanism of Action Sebaceous gland destruction (ROS) Reduction of follicular obstruction and hyperkeratosis Immunological changes Longer incubation times (3 hours or more) > long-term acne remission (ALA-PDT and MAL-PDT) Red light is deeper penetrating > more likely to activate porphyrins in sebaceous glands in PDT

4.2.2. Basal Cell Carcinoma

4.2.3. Bowen's Disease

4.2.4. Actinic Cheilitis

4.2.5. Hidradenitis Suppurativa

4.2.6. Cosmetics Photo-Aging

4.2.7. CTCL

4.2.8. Viral Infections of the skin HPV Molluscum HSV

5. Contraindications

5.1. Photosensitivity at 400-450 nm

5.1.1. Caution to other wavelengths

5.2. Porphyria

5.3. Allergies to Porphyrins

6. Adverse Effects

6.1. Phototoxic Reaction

6.2. Dyspigmentation

6.3. HSV (Prophylaxis prior Tx)

6.4. Residual photosensitivity