Cefaclor, cefprozil, and loracarbef

Cefaclor, cefprozil, and loracarbef are orally administered second-generation cephalosporins. Cefaclor is similar in many aspects to cephalexin, but differs by being more active in vitro against a number of Gramnegative bacteria (Bill and Washington, 1977). Cefprozil has sometimes been described as a third-generation cephalosporin, but its spectrum of activity is only slightly wider than that of cefaclor (Chin and Neu, 1987; Eliopoulos et al., 1987). Loracarbef is structurally similar to cefaclor but has a carbon at position 1 instead of a sulfur. It has similar in vitro activity to cefaclor, with some minor enhancement against some Gram-negative bacteria. Because loracarbef is no longer available in the USA and most other countries, discussion in this chapter focuses on cefaclor and cefprozil. The chemical structures of cefaclor, cefprozil, and loracarbef are shown in Figures 21.1, 21.2, and 21.3, respectively.