Caprolactam derivative used to enhance percutaneous absorption of physiologically active agents. Also exhibits intrinsic anti-inflammatory activity. Prepn: A. P. Swain et al., J. Org. Chem. 18, 1087 (1953). Improved synthesis: V. J. Rajadhyaksha et al., EP 95096; eidem, US 4422970 (both 1983 to Nelson). Use as skin penetrant: V. J. Rajadhyaksha, US 3989816; US 4405616 (1976, 1983 to Nelson). Anti-inflammatory activity: E. L. Nelson, US 4310525 (1982 to Nelson). Pharmacology: R. B. Stoughton, Arch. Dermatol. 118, 474 (1982). Comprehensive description: idem, Drug Dev. Ind. Pharm. 9, 725 (1983). Topical antiviral activity in vivo: M. F. Leonard et al., Chemotherapy (Basel) 33, 151 (1987).