 Although not a very active antibiotic itself, synthetic analogs of cephalosporin C, such as cefalotin, became some of the first marketed cephalosporin antibiotic drugs.Cephalosporin C strongly absorbs ultraviolet light, is stable to acid and penicillin, is non-toxic and has in vivo activity in mice.Cephalosporin C, which has a similar structure to penicillin N, was never commercialized.