Permeation enhancement of ascorbic acid by self-dissolving micropile array tip through rat skin.

Ascorbic acid (AA) loaded self-dissolving micropiles (SDMP) were prepared using chondroitin sulfate as the base for the percutaneous administration of AA. AA solution was added to dense solution of chondroitin solution, glue, and array tip, 1.0 cm(2), containing 100 SDMPs of which length was 500 microm and basal diameter was 300 microm, were prepared. Two kinds of AA array tips containing 1344.2+/-1.7 microg (high content ones) and 638.7+/-4.3 microg (low content ones) were used. In vitro dissolution study showed that more than 90% of AA were released from both SDMP array tips within 5 min. Stability experiment showed that 99.2-99.4% of AA was detected in SDMP array tips when stored at 23 degrees C for 1 week. When in vitro permeation experiments were performed after AA SDMP array was inserted to the isolated rat abdominal skin, extremely high amounts of AA, 1285.3+/-369.0 microg (95.3%) for high content SDMP tip and 405.6+/-84.3 microg (65.8%) for low content SDMP tip, were permeated for 6 h into the receptor compartment due to the break down of the skin barrier function. When AA SDMP array tip was administered to the rat skin under anesthetized condition with the different contact times, 10, 20 and 30 min, the permeated amount of AA was dependent on both the AA content in SDMP array tips and the contact time. When AA SDMP was contact to the skin for 30 min, permeated amounts of AA were 146.8+/-22.9 microg (10.9%) for high content-SDMP tip and 61.2+/-18.2 microg (9.6%) for low content SDMP tip. These results suggest the usefulness of SDMP array tip for the percutaneous absorption of AA.