Pharmacology/Actions

Ciprofloxacin is a bactericidal and a concentration dependent agent, with susceptible bacteria cell death occurring within 20–30 minutes of exposure. Ciprofloxacin has demonstrated a significant post-antibiotic effect for both gram-negative and gram-positive bacteria and is active in both stationary and growth phases of bacterial replication. Its mechanism of action is not thoroughly understood, but it is believed to act by inhibiting bacterial DNA-gyrase (a type-II topoisomerase), thereby preventing DNA supercoiling and DNA synthesis.

Both enrofloxacin and ciprofloxacin have similar spectrums of activity. These agents have good activity against many gram-negative bacilli and cocci, including most species and strains of Pseudomonas aeruginosa, Klebsiella spp., E. coli, Enterobacter, Campylobacter, Shigella, Salmonella, Aeromonas, Haemophilus, Proteus, Yersinia, Serratia, and Vibrio species. Of the currently commercially available quinolones, ciprofloxacin and enrofloxacin have the lowest MIC values for the majority of these pathogens treated. Other organisms that are generally susceptible include Brucella spp. Chlamydia trachomatis, Staphylococci (including penicillinase-producing and methicillin-resistant strains), Mycoplasma, and Mycobacterium spp. (not the etiologic agent for Johne’s disease). When combined with either ceftazidime or cefepime, fluorquinolones may have an additive or synergistic effect against certain bacteria.

 

The fluoroquinolones have variable activity against most Streptococci and are not usually recommended for use in treating these infections. These drugs have weak activity against most anaerobes and are ineffective in treating anaerobic infections.

DOSAGE

DOGS:

For susceptible infections:

a) 5–15 mg/kg PO q12h; Avoid or reduce dosage of these drugs in animals with severe renal failure; avoid in young animals or in pregnant or breeding animals. (Vaden & Papich 1995)

b) For UTI: 10 mg/kg PO once daily (q24h) for 7–14 days, 

For skin, soft tissue infections: 10–15 mg/kg PO once daily (q24h) for 7–14 days. 

For bone systemic infections, bacteremia and more resistant pathogens (e.g., Enterobacter): 20 mg/kg PO once daily (q24h) for 7–14 days (Greene et al. 2006)

c) For pyoderma: 11 mg/kg PO q12h (Miller 2005)

CATTLE: 

(excluding veal and lactating dairy) 7.5–12.5 mg/kg, SC, once 2.5–5 mg/kg, SC, q 24 h for 3–5 day.