About hydroquinonebenzenediol derivative, depigmenting agent.mechanism of action of hydroquinoneshydroquinone decreases the formation of melanin in the skin. it inhibits tyrosinase and other melanin forming enzymes and thus decreases the formation and increases the degradation of melanosomes.ssindications for hydroquinones1. melasma s2. freckles s3. hyperpigmention s4. lentigo ssspecial precautions while taking hydroquinones1. discontinue the drug if skin irritation occurs s2. care should be taken to avoid it`s entry to eyes, nose, lips or mouth s3. avoid exposure to sunlight s4. use a sunscreen and wear protective clothing when exposure to the sun s5. do not use hydroquinone topical on burned, dry, chapped, or irritated skin, or on an open wound. it could make these conditions worse s6. hepatic impairment s7. renal impairment s8. along with other topical medication on the same area