20852.(3)(a) LHC Lunts and DT Collin, US. Patent 4012444 (1977);(b) JE Clifton, I. Collins, P. Hallett, D. Hartley, L. HC Lunts, and PD Wicks, J. Med. Chem., 25,670 (1982). This paper also describes the synthesis of the isomers.(4) For reviews of the animal pharmacology, see (a) DA Richards, J. Tuckman, and BNC Prichard, Br. J. Pharmacol., 3, 849 (1976);(b) RT Brittain and GP Levy, Br. J. Clin.