Demelanizing Agents

DEMELANIZING AGENTS

They lighten hyperpigmented patches on skin.

Hydroquinone

It is a weak hypopigmenting agent. It inhibits tyrosinase and other melanin forming enzymes, decreases formation of and increases degradation of melanosomes. Regular application (as 2–6% lotion or cream) for months is required in melasma, chloasma of pregnancy, etc. The response is often incomplete and pigmentation may recur when it is discontinued, especially if exposed to sunlight; sunscreens are frequently combined. Skin irritation, rashes and allergy are possible. Care is to be taken to avoid its entry in eyes.

EUKROMA 4% cream, MELALITE: Hydroquinone 2% with glycerylester of PABA 2.8% cream. BRITE: hydroquinone 4%, glyceryl PABA 2.8% cream.

Monobenzone

A derivative of hydroquinone; potent demelanizing agent—destroys melanocytes and may cause permanent depigmentation. Full effect takes 4–6 months; treated areas should be protected from sunlight by a sunscreen. Its bleaching action is somewhat irregular: ugly depigmented patches can appear. Erythema and eczema may also result. Therefore, its use should be restricted to patients with widespread vitiligo —to reduce the colour contrast between pigmented and nonpigmented areas and for postinflammatory melasma; 5% lotion or 20% ointment is applied 2–3 times daily.

BENOQUIN 20% ointment.

Azelaic acid

It is a drug for acne (see p. 853) that is also effective in hyperpigmentary disorders including melasma. It appears to act by inhibiting the melanin forming enzyme tyrosinase. However, it is a weak demelanizing agent with reversible hypopigmentary action.

Azelaic acid is used as a 10%, 20% cream. The only side effect is mild and transient local irritation.

AZIDERM 10%, 20% cream.