Percutaneous absorption, blood levels, and urinary excretion of resorcinol applied topically in humans

The absorption and metabolic disposition of 2% resorcinol applied topically in a hydroalcoholic vehicle was determined in three human subjects. The drug penetrated the skin at a rate of 0.37 micrograms/cm2/hour. After 2 weeks of bid application of 800 mg resorcinol to about 30% of body surface of each subject, an average of 1.64% of the dosage was being excreted in 24-hour urine specimens as the glucuronide or as the sulfate conjugate. There was no resorcinol in blood drawn at weeks 1, 2, 3, and 4, or nor were there any abnormalities in thyroid function or blood chemistries at weeks 2, 3, and 4. Resorcinol (2%) appears safe for topical use in humans.