Cefalexin monohydrate is a cephalosporin antibiotic. Target: Antibacterial Cefalexin (INN, BAN) or cephalexin (USAN, AAN) is a first-generation cephalosporin antibiotic introduced in 1967 by Eli Lilly and Company. It is an orally administered agent with a similar antimicrobial spectrum to the intravenous agents cefalotin and cefazolin. It was first marketed as Keflex (Lilly), and is marketed under several other trade names. As of 2008, cefalexin was the most popular cephalosporin antibiotic in the United States, with more than 25 million prescriptions of its generic versions alone, for US$255 million in sales (though less popular than two other antibiotics, amoxicillin and azithromycin, each with 50 million prescriptions per year). Cefalexin is marketed by generic pharmaceutical manufacturers under a wide range of brand names, including: Apo-Cephalex, Biocef, Cefanox, Ceforal, Cephabos, Cephalexin, Cephorum, Ceporex, Cilex, Ialex, Ibilex, Kefexin, Keflet, Keflex, Rekosporin, Keforal, Keftab, Keftal, Lopilexin, Larixin, Novo-Lexin, Ospexin, Tenkorex, Zephalexin, Panixine Disperdose, Rancef, Sialexin, Sporidex and Ulexin. A version of Keflex 750 mg capsules is marketed for twice-daily dosage, to improve compliance. However, it is not a sustained release formulation, and since it is more expensive than the older strengths, some physicians prescribe three 250 mg capsules to be taken twice daily, as a less expensive alternative.