Photodynamic Therapy For Acne

Introduction

Photodynamic therapy (PDT) is a form of therapy that targets cancer cells by combining light and specific drugs, frequently referred to as photosensitising agents. Only when specific types of light have "turned on" or activated the medications do they start to function. 

Photodynamic therapy is sometimes referred to as ‘photochemotherapy’, ‘photoradiation therapy’, or ‘phototherapy’.¹ The most common use of dynamic therapy is local therapy, which targets a specific area of the body.² 

Here are a list of common conditions that are treated with photosensitiser drugs: 

• Age-related macular (central part of the retina) degeneration, leading to vision loss
• Acne
• Psoriasis 
• Skin cancers 
• Lung conditions
• Brain conditions
• Bladder conditions 
• Pancreas conditions 
• Bile duct conditions 
• Oesophagus (your food pipe) conditions
• Head conditions
• Neck conditions 

PDT can also help treat bacterial, viral and fungal infections on top of these conditions.

Studies have also shown that this light-based therapy can boost immunity, giving your body additional defence against cancerous and precancerous cells.³ 

Acne is a common skin condition brought on by blocked pores. All types of pimples, including blackheads and whiteheads, are caused by pore blockages. Pus-filled, painful skin lesions are called acne vulgaris. Acne vulgaris is the term used in medicine to describe acne.⁴ All ages are affected by acne, however teenagers are the group most frequently affected.⁵ PDT was originally created to treat dry patches of skin caused by sun damage (actinic/solar keratoses) and is now considered a leading acne treatment option. 

In 2000, Hongcharu and associates released the first case studies of PDT-treated acne in the US. The most common photosensitisers used in treatment are MAL (methyl aminolevulinate) or ALA (5-aminolevulinic acid), both of which are precursors of PpIX (protoporphyrin IX) when combined with a laser or broadband light source. When photosensitiser precursors grow up, particularly in the sebaceous glands of your skin, larger quantities of the light-sensitising agent PpIX are generated. There, they are merged into the heme synthesis pathway.⁶

Mechanism of photodynamic therapy

The basic concept is that a photosensitiser concentrates in rapidly multiplying cells, which leads to the production of light-sensitive porphyrins. This then produces ‘singlet oxygen’, which results in cell death and the production of free radicals. 

The most often utilized photosensitizer is ALA.⁸ The primary uses of ALA and its by-products are in the treatment of:

• actinic keratosis
• superficial basal cell carcinoma
• squamous cell skin cancer in situ
• and skin cancer or its precursors

Role of photodynamic therapy in acne

PDT is now a popular substitute for acne medication. The first Americans to use PDT for acne were Hongcharu et al. in 2000.¹⁰ A photosensitizer is used with a laser or broad-band light source. Higher amounts of the photosensitizing agent PpIX is produced when these precursors of the photosensitizer accumulate in the sebaceous glands of the skin and are incorporated into the heme synthesis pathway.¹¹

When the activated photosensitiser is exposed to visible light and oxygen, it produces reactive species of oxygen, which can cause selective phototoxicity in the targeted sebaceous units. The precise mechanism of action of photodynamic therapy in acne treatment has yet to be discovered, however. 

PDT is expected to have anti-inflammatory characteristics, reduce inflammation, diminish sebum gland size and function, and affect the immune system.^10,12,13 Multiple research investigations have shown PDT’s antibacterial capabilities, although no decrease in the frequency of P. acnes cases has been observed.¹⁴ 

Activation of photosynthesiser with light

PDT activates the photosensitiser by a number of light sources and energy-based methods.¹⁰ Although the photosensitiser can be triggered at a variety of wavelengths corresponding and the depth of penetration into the skin is determined by the wavelength of light. 

Since red light has a longer wavelength than blue light, it can target the sebaceous glands and penetrate deeper into the dermis.⁶ It seems that the most effective wavelength for photoactivating P. acnes is blue light.⁷ Chlorophyll, indole-3-acetic acid (IAA), indocyanine green (ICG), and silica-coated in gold are less frequently used photosensitizers. Since chlorophyll has a shorter incubation period and is rapidly metabolized, it minimizes phototoxic effects when used as a photosensitizing agent for PDT.⁶

Photodynamic therapy procedure for acne treatment

Preparing your skin for the session

• Take at least three days off from the sun
• Before your treatment, use a facial scrub or microdermabrasion to remove dead skin, blackheads, and debris from the skin's surface
• The photosensitising agent will then be applied to your skin by your doctor
• The photosensitising chemical may need a few minutes or several hours to fully permeate the skin

Photodynamic therapy

• When it's time for treatment, your light therapy specialist will use a medical light to activate the photosensitising solution
• The photosensitising component increases the effectiveness of light to destroy acne-causing germs on the skin when oxygen and light are both present
• The length of time the light treatment takes will depend on the size of the damaged region and the state of your skin

After treatment care

• It's important to safeguard your skin during your recovery 
• Before you leave consult with your physician and make sure all other skin products functions well with your treatment and won't create any negative responses with your physician 
• For three days, stay out of direct and intense sunshine to protect your recovering skin
• It can take several photodynamic treatment sessions to get the best effects¹⁵

Advantages of photodynamic therapy for acne

Based on nearly 20 years of PDT treatment for severe acne, PDT provides the following advantages over systematic medication therapy: 

• quick onset
• good efficacy
• high selectivity 
• no systemic side responses
• no drug resistance
• low recurrence rate¹⁶ 
• better texture throughout the skin
• and decreases the oiliness of the skin¹⁷ 

Summary

• photodynamic therapy (PDT) has shown promise as a treatment for a number of dermatological issues, including acne
• PDT targets and eliminates acne-causing bacteria while simultaneously treating inflammation and lowering sebum production by combining light activation with particular photosensitizing drugs
• To successfully eradicate microorganisms and enhance skin condition, a photosensitising solution is applied, and is activated by light treatment
• PDT has a number of benefits over conventional drug therapy, such as a low recurrence rate, minimal systemic side effects, early onset, high efficacy, and selectivity
• PDT can also improve skin texture and lessen oiliness, giving patients benefits that are both cosmetic and therapeutic
• PDT shows potential as a useful option in the treatment of acne and other dermatological diseases with more research and technological developments