Effect of Cationic Surfactants on the Transdermal Permeation of Ionized Indomethacin

In an attempt to enhance the skin permeation rate of ionized indomethacin by ion-pairiig, a group of cationic surfactants were evaluated to determine their potential as counter-ions. Permeation rates through hairless rat skin were measured in vitro. The ion-pairing agents used were all quaternary ammonium compounds. Most enhanced the skin permeation of indomethacin to varying magnitudes and through different mechanisms. Some involved increased drug solubilization in the aqueous vehicle while others demonstrated permeability increase as a function of partitioning. One surfactant did not exert an apparent effect on any of the permeation parameters. Of ArquadR 12, ArquadR 16, Cetylpyridinium chlorideR and Benzalkonium chlorideR, only the last surfactant clearly indicated its ability to pair with indomethacin.