Absorption of 8-hydroxyquinolines through the human skin

The skin absorption of clioquinol and chloroquinaldol in ointment or cream base was studied in fourteen patients with widespread dermatoses. A serum concentration in the range of 0.3--1.3 microgram/ml using clioquinol and 0.05--0.1 microgram/ml with chloroquinaldol was reached by the second day and persisted throughout the topical treatment. The mean serum half-life of clioquinol and of chloroquinaldol was estimated to 25 and 6 hours, respectively. Local application of zinc oxide ointment after the end of the treatment chelate-bound the skin deposits of clioquinol and lowered the serum half-life to 11 hours. The mean daily urinary excretion of the applied amount of clioquinol and chloroquinaldol was 4.5 and 6%, respectively.