*3.1.2 Administration of treatment*

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

adverse reaction, the patient can continue with the application of the cream on the areas of top priority and then move in stages for low priority areas. To avoid contact dermatitis, different concentrations of MBEH can be used. MBEH can be diluted to 5% for use on the neck, 10% on the face, and 20% on the arms and legs. In patients who fail to respond to 20% MBEH over a course of 3 to 4 months, the concentration of MBEH can be increased to 30% and then further to 40%. Concentrations of 30 and 40% MBEH have been used primarily on the extremities, especially the elbows and knees. Concentrations greater than this are not recommended [8].

It takes anywhere between 4 and 12 months for gradual depigmentation [8]. It is to be noted that depigmentation is mostly irreversible and histologically associated with loss of melanosomes and melanocytes [1].

### *3.1.3 Precautions*

Patients should always be informed and well instructed about certain precautions while using MBEH.


#### *3.1.4 Side effects*

Irritant contact dermatitis and common allergic reactions can develop [9]. In which event, application of MBEH is stopped, and open wet dressings are applied to the affected area along with topical steroids. Once the dermatitis has subsided, MBEH can be restarted at a lower concentration of 5% [8]. Other side effects include exogenous ochronosis [10], unmasking of telangiectasias and phlebectasias on the lower extremities [8], pruritus, xerosis, erythema, rash, edema, conjunctival melanosis, and distant depigmentation [4].

Risk of carcinogenesis with MBEH has not been reported but cannot be ruled out, and hence it is banned from the European Union since 2001 in cosmetics [11].

#### *3.1.5 Combination therapy*

All-trans retinoic acid (RA), which is a vitamin A derivative primarily employed in the treatment of acne, is shown to serve as a weak depigmenting agent when used for several weeks.

**59**

patients.

*Depigmentation Therapies in Vitiligo*

melanocytes [12–15].

(HA) or mequinol [1].

*3.2.3 Side effects*

**3.3 Phenol solution (88%)**

*3.3.1 Mechanism of action*

tissue up to the upper reticular dermis.

*3.2.1 Mechanism of action*

with a Q-switched ruby laser.

*3.2.2 Administration of treatment*

better the results that were obtained [1].

after a twice-daily application of up to 24 weeks [1].

from sunlight is necessary or repigmentation risk is high [1, 11].

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

A combination or RA and MBEH induced significant depigmentation within 4–8 weeks. Nair et al. proposed that RA might enhance the skin penetration of depigmenting agents. Thus, RA increases the susceptibility of melanocytes to hydroquinone and 4-hydroxyanisole via the impairment of glutathione-dependent defense mechanisms of melanocytes and reducing melanogenesis activity in viable

This compound is a phenol derivative and is also known as p-hydroxyanisole

Mequinol acts in the similar way as MBEH acts. This compound usually acts via a dose-dependent response manner. It can be used as monotherapy or in conjunction

The compound is used in a 20% concentration in an oil/water cream base. As with MBEH, cream is applied on an initial test patch to observe for any allergic reactions. If there are no reactions, the patient is advised to apply cream twice daily until complete depigmentation is observed [16]. The effectiveness of 4-MP has been correlated with the duration of the use of the cream; the longer the cream was used,

A combination product of 2% 4-hydroxyanisole (mequinol) and 0.01% tretinoin was tested in a double-blind multicentric study and was found to significantly improve solar lentigines and related hyperpigmented lesions of the face and hands

Side effects include mild burning or itching, irregular leukoderma, contact dermatitis, ochronosis, and risk of carcinogenesis cannot be ruled out [11]. Protection

Phenol is an inexpensive peeling agent having medium-depth capability and used for treatment of photodamage or rhytids. The toxicity of phenol toward melanocytes is well documented. Phenol has the ability to penetrate deeper into the

Phenol is involved in melanogenesis, inducing coagulation of protein in the epidermis. The melanocytes lose their capacity to synthesize melanocytes normally. This property of phenol is different than that of MBEH and hydroquinone wherein they destroy the melanocytes [17]. Hence, 88% phenol can be used as therapeutic option to eliminate residual normally pigmented lesions in

**3.2 Monomethyl ether of hydroquinone/4–0 methoxyphenol**

#### *Depigmentation Therapies in Vitiligo DOI: http://dx.doi.org/10.5772/intechopen.84271*

A combination or RA and MBEH induced significant depigmentation within 4–8 weeks. Nair et al. proposed that RA might enhance the skin penetration of depigmenting agents. Thus, RA increases the susceptibility of melanocytes to hydroquinone and 4-hydroxyanisole via the impairment of glutathione-dependent defense mechanisms of melanocytes and reducing melanogenesis activity in viable melanocytes [12–15].
