Comparative clinical evaluation of mezlocillin and carbenicillin

Mezlocillin (MZL) is a semi-synthetic acylureidopenicillin with an improved spectrum of activity over carbenicillin (CBL). Sixty-eight patients with serious systemic infections were studied in a comparative, prospective, controlled randomized, non-blind design. Twenty-seven patients were treated with MZL and 27 with CBL. There were 30 sites of infection in the MZL group and 29 in the CBL: lower respiratory (MZL 14/CBL 21); septicaemia (5/4); soft tissues (6/1); intra-abdominal (2/2); hepatobiliary (1/1); upper respiratory (1/0); urinary tract (1/0). Sixteen cases treated with MZL were classified as cured (59.3%); nine as improved and two failed to respond. For CBL the corresponding results were 17 cured (63%); seven improved and two failures. Adverse reactions were observed in 9 patients of each group. MZL at a dose of 16 g/day was shown to be as effective as a CBL at 30 g/day for serious systemic infections.