Hydroquinone is an aromatic organic compound widely recognized for its skin-depigmenting and melanin-reducing activity. It is primarily used as an active pharmaceutical ingredient in topical dermatological preparations intended to reduce areas of localized hyperpigmentation.
Hydroquinone acts primarily by inhibiting tyrosinase, an enzyme involved in melanin biosynthesis. This makes it an important pharmaceutical ingredient in formulations developed for pigmentation-related dermatological conditions.
Hydroquinone is a specialized dermatological pharmaceutical ingredient requiring controlled manufacturing, purification and analytical testing. API quality control focuses on chemical identity, assay, related substances, residual solvents, water content and control of oxidative impurities.
Hydroquinone can undergo oxidation under unsuitable conditions, so appropriate packaging, storage and handling are important for maintaining pharmaceutical quality.
CAS Number: 123-31-9
Molecular Formula: C6H6O2
Molecular Weight: 110.11 g/mol
Chemical Name: Benzene-1,4-diol
Drug Class: Depigmenting Agent
Pharmacological Class: Tyrosinase Inhibitor
Therapeutic Class: Dermatological Agent
Therapeutic Area: Dermatology
Hydroquinone reduces melanin production primarily through inhibition of tyrosinase, an enzyme involved in the conversion of tyrosine to melanin.
It also affects melanocyte function and melanin formation, resulting in gradual reduction of pigmentation with continued topical use.
Hydroquinone has been used in topical formulations for conditions involving localized hyperpigmentation, including:
The permitted concentration, indication and regulatory status of hydroquinone vary by country and formulation.
Hydroquinone is commonly incorporated into topical creams, gels and lotions designed for pigmentation management. It may also be formulated with other dermatological active ingredients depending on the intended application.
Because prolonged or inappropriate use can cause adverse skin effects, pharmaceutical formulations should comply with applicable regulatory requirements and approved labeling.
Hydroquinone is generally obtained as a white crystalline solid. It is soluble in water and more soluble in alcohol and certain organic solvents.
The molecule contains two hydroxyl groups positioned para to each other on a benzene ring. Its chemical structure allows it to undergo oxidation, which can result in discoloration and formation of quinone-related impurities.
Hydroquinone API quality evaluation may include:
Hydroquinone should be stored in a tightly closed container, protected from light, excessive heat and moisture. Exposure to air and unsuitable storage conditions may promote oxidation and discoloration.
Hydroquinone remains relevant to dermatological research involving melanin biosynthesis, tyrosinase inhibition, pigmentation disorders and topical depigmenting formulations.
Hydroquinone is a pharmaceutical dermatological ingredient with CAS Number 123-31-9, molecular formula C6H6O2, and molecular weight 110.11 g/mol. It acts primarily by inhibiting tyrosinase and reducing melanin production and has been used in topical formulations for selected hyperpigmentation disorders.
| Parameter | Specification |
|---|---|
| Appearance | White to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 99.0% – 101.0% |
| Loss on Drying | NMT 1.0% |
| Residue on Ignition | NMT 0.5% |
| Heavy Metals | NMT 10 ppm |
| pH (1% Solution) | 4.0 – 7.0 |
| Individual Impurity | NMT 0.5% |
| Melting Point | 172–175°C |