In vitro studies on penetration of terpenes from matrix-type transdermal systems through human skin

Polyurethane matrices containing up to 39% of the terpenes eucalyptol, L-li monene, D-limonene, dipentene or terpinolene were produced. Release of the terpenes directly to the acceptor fluid, as well as through isolated human epidermis and dermis, was studied. In the presence of dermis the penetratio n profiles were very similar to the release profiles, indicating that dermi s does not present a barrier for penetration of terpenes., For all terpenes the penetration was slower in the presence of epidermis (K-p was in the ra nge 0.21-1.8 x 10(-3) cm/h). Release and penetration through the epidermis and dermis were fastest for dipenetene (mixture of D-limonene and L-limonen e), being at least 3-4 times faster than for D-limonene and L-limonene. Lar ge amounts of terpenes found in epidermis (approximately 1.5 mg/cm(2)) indi cate that affinity of these compounds to the stratum corneum is very high. (C) 2001 Elsevier Science B.V. All rights reserved.