Cefonicid is a second-generation cephalosporin antibiotic.

Cephalosporins, the largest and most diverse family of antibiotics of the beta-lactam group, are structurally and pharmacologically related to the penicillins.

In vitro: Cefonicid was found to be similar to cefamandole in its superiority to first generation cephalosporins against several enterobacteriaceae and Haemophilus influenzae, such as beta-lactamase-producing strains. Its activity against Staphylococcus aureus was similar to that of cefoxitin and inferior to cefamandole and first generation cephalosporins. Cefonicid has excellent in-vitro activity against Neisseria gonorrhoeae, but is inactive against Pseudomonas, Serratia, Acinetobacter, and Bacteroides fragilis [1].

In vivo: The purpose of a previous study was to determine whether cefonicid caused testicular toxicity when subcutaneously administered to Sprague-Dawley male rats at doses of 50 to 1,000 mg/kg per day. The histological findings were confirmed by marked reductions in testicular sperm production rates and cauda epididymal sperm numbers. In addition, cefonicid had no treatment-related adverse effects on the sexual maturation males [2].

Clinical trial: Cefonicid was found to be comparable in efficacy with cefamandole or cefazolin in the treatment of patients with urinary tract, lower respiratory tract, and soft tissue and bone infections. It was also compared with penicillin in the treatment of uncomplicated gonorrhoea. Single doses of cefonicid appear to offer a similar degree of protection against post-surgical infection as multiple doses of other antibiotics [1].

References:
[1] Saltiel, E; Brogden, R.  N. (1986). Cefonicid. A review of its antibacterial activity, pharmacological properties and therapeutic use. Drugs. 32 (3): 222–59.
[2] Manson JM, Zolna LE, Kang YJ, Johnson CM.  Effects of cefonicid and other cephalosporin antibiotics on male sexual development in rats. Antimicrob Agents Chemother. 1987 Jul;31(7):991-7.