Since its introduction in 1963 indomethacin (l-(p-chlorobenzoyl)-5-methoxy-2-methylindol-3-acetic acid) has been reported as an analgesic of value in the treatment of osteoarthitis (Hart and Boardman, 1963 ; Wanka et al., 1964; Percy et al., 1964) and ankylosing spondylitis (Katz et al., 1963 ; Hart and Boardman, 1963 ; Smyth and Godfrey, 1964; Percy et al., 1964; Rothermich, 1964; Michotte and...