Possible Interaction: Hydroquinone and Tretinoin

“BACKGROUND Although an aggressive use of tretinoin along with hydroquinone enables an efficient treatment of hyperpigmented skin lesions, irritant dermatitis remains to be solved.”

“The combination of all-trans-retinoic acid (tretinoin, TRA) with hydroquinone or 4-hydroxyanisole is also known to produce synergetic skin depigmentation.”

“The use of retinoids may be too harsh in this skin type, and the strengths of hydroquinone used can produce different clinical results because strengths greater than 4% can also cause irritation and post inflammation pigmentation.”

“BACKGROUND Retinoic acid (RA) enhances skin-lightening capabilities of hydroquinone (HQ), at least in part, by facilitating desquamation which leads to increase penetration of HQ.”

“Moreover, the three components of Kligman’s formula have a synergic action: tretinoin prevents the oxidation of hydroquinone and improves its epidermal penetration thanks to a local irritation; dexamethasone reduces the irritative effects of hypopigmenting agents and induces local immunosuppression.”

“BACKGROUND Although combined use of tretinoin (all-trans-retinoic acid; atRA) and hydroquinone improves various hyperpigmented lesions, the pharmacologic instability of atRA and atRA-induced irritant dermatitis are difficult unsolved problems.”

“Furthermore, RA in combination with hydroquinone or 4‐hydroxyanisole, or azelaic acid increases the potency of depigmenting agents for the treatment of melasma, actinic lentigines, and postinflammatory hypermelanosis.”

“The addition of retinoids may facilitate epidermal penetration of hydroquinone and prevent its oxidation.”

“&NA; Melasma treatment with combined retinoic acid RA ) and hydroquinone (HQ) usually causes unsatisfactory outcomes and safety concerns.”

“Chemical conjugation of RA with HQ increased the lipophilicity and thus the skin absorption.”

“ Tretinoin (used for enhancing the skin-whitening effect of HQ) and resin monomers (used to prevent polymerization of HQ) lowered the HQ concentration needed to establish sensitization to HQ.”