**2. Selecting the right candidate**

Selection of an appropriate patient is of utmost importance in depigmentation therapy. The option of depigmentation should be made available to only those patients having extensive vitiligo. Detailed and thorough consultation sessions should be conducted with the patient and their families (preferably 2–3 sessions), explaining to them in detail that this therapeutic modality utilizes a potent depigmenting agent and should not be used for cosmetic purposes [2, 3]. They should be explained with all realistic expectations, treatment time frame, the cost involved, and side effects if any, and that once one particular type of treatment is done, they will not be a good candidate for any other type of treatment. Subjects with skin types (V and VI) with a disfiguring contrast between dark-pigmented skin and white vitiliginous areas, especially involving exposed areas (face or the hands), may be a candidate for depigmentation. Moreover, incomplete or trichrome repigmentation (e.g., when using UV light) may cause more disfigurement, thus making such individuals good candidates for depigmentation therapy. The patients should be informed that even after depigmentation, spontaneous repigmentation might occur in vitiligo lesions, warranting additional depigmenting cycles. Patients must be informed that these treatments lead to a definitive irreversible depigmentation. Younger patients with extensive involvement can be given an option of repigmentation instead of opting for depigmentation explaining that complete repigmentation may or may not be achieved. Depigmentation therapy should be avoided in children less than 12 years of age [4].

**57**

*Depigmentation Therapies in Vitiligo*

*DOI: http://dx.doi.org/10.5772/intechopen.84271*

**3. Topical therapies for depigmentation**

depigmentation therapy in vitiligo patients.

*3.1.1 Mechanism of action*

exosomes.

keratinocytes" [6].

tation in animal studies [7].

*3.1.2 Administration of treatment*

**3.1 Monobenzyl ether of hydroquinone (MBEH)**

MBEH (monobenzone, p-benzyloxy-phenol) is the most common topical depigmenting agent used mainly because it is the only product approved by the United States Food and Drug Administration (USFDA) for depigmentation in vitiligo, if the affected body surface area is more than 50% [1]. It is a hydroquinone (HQ ) derivative and was first introduced in 1930s. MBEH is the first-line agent for

There are multiple pathways through which MBEH causes depigmentation [5]:

1.Reaction with tyrosinase enzyme during melanin synthesis leads to conversion of MBEH to quinones. The reactive quinone products formed bind with cysteine found in tyrosinase proteins (sulfhydryl (-SH) group) to form haptencarrier compounds resulting in formation of neoantigens. These neoantigens stimulate a systemic, melanocyte destruction and an inflammatory reaction.

2.Another result of MBEH conversion by tyrosinase is production of reactive oxygen species (ROS). ROS leads to lysosomal degradation of melanosomes. Additionally, there is interference of the melanosome structure and membranes, following which the major histocompatibility complex (MHC) class I and II routes and initiation of melanocyte Ag-specific T-cell responses cause an

3.ROS also contributes to an innate immune response due to the release of

4.MBEH-exposed skin presents with rapid and persistent innate immune activation. It is quoted by Gupta et al. "that MBEH is a contact-sensitizer, inducer of a type IV delayed type hypersensitivity response against the quinone hapten. However, this only occurs if there is production of pro-inflammatory cytokines such as interleukin (IL)-1b and IL-18 by the Langerhans cells or

There have been reports that when MBEH therapy was combined with all-trans retinoic acid (ATRA), it enhanced depigmentation process and the melanocytotoxic effects via inhibition of the enzyme glutathione S-transferase in melanocytes. This could be a possible way to avoid contact dermatitis when using high concentrations of 40% MBEH. However, combination of ATRA-MBEH did not affect hair pigmen-

After the patient has been duly consulted and informed about all the possible outcomes and consequences of the treatment, the depigmentation therapy is initiated. Application of MBEH can be done by the patient at home. Initially, the exposed areas are treated. A test spot is advised over a normal pigmented skin (usually forearm) to assess the development of contact dermatitis. If there is no

increase in surface expression of melanosomal antigens.
