Depigmentation therapy for vitiligo

Who is suitable for depigmentation therapy?

Depigmentation therapy may be considered in the treatment of vitiligo treatment resistant affecting more than 50% of the body surface area or affecting cosmetically sensitive exposed body sites.

Informed consent for treatment with depigmenting agents.

Before starting depigmentation therapy, the patient must understand:

1. The permanent nature of the treatment.
2. The need for lifelong strict sun protection to maintain benefits and reduce the risk of sun damage, including to the skin. Cancer.
3. The slow response to treatment and the need for "touch-up" sessions
4. The potentially high cost of treatment
5. Common and rare side effects and safety issues
6. Risk of patchy and incomplete repigmentation
7. Psychosocial and cultural issues that can arise from the change in skin color.

Patients should have the opportunity to discuss treatment options with family and friends.

Hydroquinone monobenzyl ether

MBEH or monobenzone is the most commonly used depigmenting agent in vitiligo. It is the only depigmentation treatment for extensive vitiligo that has been approved by the FDA (Food and Drug Administration, United States of America).

MBEH is a derivative of hydroquinone. Unlike hydroquinone, it almost always causes irreversible depigmentation, since it causes the death of melanocytes (the cells that make up the skin pigment or melanin)

MBEH is available as 20% cream, although it can be formulated up to a 40% for difficult areas like elbows and knees. In the US, it is available as Benoquin® 20% cream. MBEH is not approved by Medsafe for use in New Zealand, but doctors can obtain it from the manufacturer in Section 29. The patient must pay the full cost of treatment.

Adverse reactions hydroquinone monobenzyl ether

Adverse reactions of MBEH are mainly mild.

• Transient Irritation: Discontinue treatment if burning sensation is severe.
• Contact irritating dermatitis (burning, climbing, dry skin, swelling of the treated sites): stop the treatment and apply current corticosteroids to the affected areas. When the dermatitis subsides, consider using a weaker strength of MBEH.
• Less often, sensitization or allergy MBEH causes allergic contact dermatitis: permanently discontinue treatment and apply topical corticosteroids to affected areas.
• Loss of color (leukoderma) in places far from the area of application of the cream.
• exogenous Ochronosis (ash-brown pigmentation) after prolonged use of MBEH may include pigment statement at conjunctiva and cornea of the eyes
• There are no safety data available for the use of MBEH in women who may be pregnant or lactating.
• The safety of MBEH in children under 12 years of age has not been established.

How do I use monobenzyl ether of hydroquinone?

• Tolerance to MBEH should be tested before starting treatment on facial skin. Apply MBEH Cream once a day for two weeks to a small area, such as the upper arm, then increase to twice a day.
• If tolerated, a thin layer of MBEH cream should be rubbed in twice daily pigmented areas to lighten.
• Do not apply the cream to the eyelids or mucous membrane surfaces
• Avoid sun exposure at all times to prevent color from returning in patches.

Depigmentation is usually achieved after 1 to 4 months, however it can take up to 12 months to complete depigmentation of a particular site.

Treatment should be discontinued if desired results are not achieved after 4 months of use. Once the desired degree of depigmentation is achieved, the cream can be applied intermittently to maintain this, usually twice a week.

After treatment, white skin will be sensitive to the sun for a lifetime. Apply broad spectrum SPF50+ sunscreen to all fair skin at least daily.

Hydroquinone monomethyl ether

Monomethyl ether of hydroquinone (MMEH) is also known as 4-methoxyphenol, mequinol, or p-hydroxyanisole.

1. MMEH has similar melanocytotoxic properties to MBEH.
2. MMEH is generally compounded as a cream to 20%.
3. MMEH is applied in a similar way to MBEH.
4. Compared to MBEH, MMEH takes longer to achieve depigmentation, typically 4-12 months.
5. Skin irritation from MMEH is less common and less severe than with MBEH.

Phenol

Phenol is relatively cheap. It has traditionally been used for deep chemical peels. phenol is toxic melanocytes, and prevents them from synthesizing melanin. High doses of phenol (eg, 88%) are also systemically toxic and should not be applied to large areas. It should be used with great caution because it can cause severe chemical burns, heart arrhythmias and other dangers

Phenol is used to treat small areas of persistent pigment in vitiligo, i.e. <20% of the face or neck area. For safety, use only 0.5-1 ml per session and the duration of the application should not exceed 60 minutes. Phenol must be applied by an experienced physician.

• Clean the skin with alcohol.
• Apply a cotton swab moistened with phenol to treat small areas until glazed.
• The maximum amount allowed per session is 1 ml.
• A burning sensation lasts about a minute and gradually decreases in intensity over minutes to hours.
• Two treatments given 6 weeks apart are usually sufficient.
• Post-procedure care includes the normal saline soaks and mild to moderate topical corticosteroids.

Side effects and risks of phenol include:

• Scars
• Dyschromia (irregular pigmentation/depigmentation)
• Located or disseminated herpes simplex virus infection. antiviral prophylaxis with acyclovir should be considered.
• Corrosion of any tissue with which it comes into contact, for inhalation, ingestionor direct skin contact.
• The concentration of 88% rapidly coagulates the epidermis and therefore prevents its own percutaneous penetration, compared to traditional 40-50% phenol peels.
• Systemic toxicity results in cardiovascular shock, cardiac arrhythmias, bradycardiaand metabolic acidosis. These have been reported within 6 hours of phenol peeling procedures.

Lasers

Q-Switched lasers, such as ruby (694nm), alexandrite (755nm), and Nd:YAG (532nm and 1064nm) can be used alone or in combination with topical depigmenting agents such as MBEH or MMEH. These lasers work as depigmenting agents by selectively destroying melanin and melanin-containing cells.

The main disadvantages of lasers in depigmentation therapy are:

• High price
• Possible need for local anesthetics due to pain.
• Possible treatment failure
• Reappearance pigmentation

Cryotherapy

Liquid nitrogen cryotherapy is a cost-effective permanent depigmentation treatment when rapid depigmentation of a small area is desired. It is simple, easy for an experienced clinician to perform, and requires only a short preparation time. Melanocytes are extremely sensitive to cryogenic damage compared to keratinocytes and cryotherapy can cause permanent loss of color (depigmentation) after treatment.

• Single freeze-thaw cycles of 10-20 seconds are recommended, although one study has used two freeze-thaw cycles.
• Various techniques are described, including the use of a cryoprobe held approximately 40 mm from the skin.
• The best cosmetic results are usually seen 4 weeks after cryotherapy.
• The procedure may need to be repeated at 4-6 week intervals for partially depigmented lesions until complete depigmentation occurs.

The disadvantages of cryotherapy include:

• Pain
• Not suitable for large pigmented areas.
• Dyschromia (irregular pigmentation/depigmentation)
• Recurrence of pigmentation
• Scarring (rare).

Combined therapies

There are some reports that MBEH or MMEH combine with a topical retinoid how tretinoin can overcome treatment resistance and improve treatment effectiveness. Retinoids help by inhibiting melanocyte enzyme glutathione S-transferase.

MBEH or MMEH can also be used in combination with cryotherapy, or To be treatment.

Other potential depigmentation treatments

Imatinib

Imatinib is a drug used to chronic myeloid leukemia, where skin depigmentation has been reported as a side effect within 4-12 weeks of receiving this medication. The suggested mechanism of action is that imatinib mesylate, a tyrosine kinase inhibitor, interferes with the production of melanin.

Imiquimod

Imiquimod is an immune response modifier, most often used in the treatment of superficial skin cancers and genital warts. One of the side effects of treatment is sometimes permanent. hypopigmentation, which may occur after 3 months of treatment. The postulated mechanism of action is that imiquimod can induce apoptosis of melanocytes

Diphencyprone

Diphencyprone, also called diphenylcyclopropenone, is used in dermatology to treat conditions with alterations immune states, such as alopecia areata. Diphencyprone solution has been observed to sometimes result in hypopigmentation or complete depigmentation in treated areas, possibly due to its immunomodulator Effects Onset of depigmentation is reported to occur after 10 months, and can occur even at concentrations as low as 0.0001%.

experimental agents

Several phenolic compounds, including hydroquinone in concentrations higher than 4%, 4-ethoxyphenol, and 4-methylcatechol, are being tested for their depigmenting effects in animals and show promise. There is some suggestion that IFN-γ, busulfan, and some melanoma Vaccines (immunotherapy) have depigmenting activity.

Herbal products and depigmentation

The most common herbs used by traditional healers for voluntary depigmentation in Africa are:

• Brillantaisia ​​cicatricosa Lindau (Acanthaceae)
• Chenopodium ugandae (Aellen) Aellen (Chenopodiaceae)
• Dolichopentas longiflora Oliv. (Rubiaceae)
• Protea madiensis Oliv. (Proteaceae)
• Sesamum angolense Welw. (Pedaliaceae).
• Ethanol extracts from the leaves of Myrica rubra.

In vitro studies have indicated that these herbs may have effects on melanin production by melanocytes. This represents a potential area for future studies.