"New" antimicrobials in veterinary medicine (Proceedings)
Unasyn (Ampicillin / sulbactam)
Unasyn 1.5 g vial (Generic ~$4.50) is commercially available containing ampicillin 1 g and sulbactam 0.5 g. Sulbactam is a beta lactamase inhibitor, therefore many people think of this drug as "injectable Clavamox." Unasyn is a broad spectrum antimicrobial with activity against Gram (+), Gram (-), anaerobes, Enterococcus spp, Leptospirosis spp. In comparison, to generic Unasyn ampicillin 1 g vial costs ~$4.75.
Dosing30 – 40 mg/kg IV/SC/IM q 6-12 hours
Results in an ampicillin dose of 20-27 mg/kg
Cefpodoxime is a 3rd generation oral cephalosporin, however it does not penetrate BBB, prostate, or aqueous humor. It is not active against Pseudomonas aeruginosa. The wholesale cost of cefpodoxime is ~ $2 / 200 mg tab therefore a 20 kg dog administered cefpodoxime for 10 d would cost $10-20 (wholesale). Cefpodoxime has similar efficacy as cephalexin for Staph infections (i.e. pyoderma) with increased activity against E coli.
5-10 mg/kg PO q 24 h
Cefovecin is a veterinary specific 3rd generation cephalosporin that is primarily eliminated by renal mechanisms. Potential uses for cefovecin include: Bacteroides, E Coli, Staph, Strep, Pasteurella. However Pseudomonas, Bordetella, Enterococcus, and Clostridium are typically resistant. Cefovecin has a Long half-life due to high protein binding and slow clearance which is similar between IV and SC admin. Cefovecin is not a depot formula. It is labeled for SC admin only. Cefovecin has persistent drug concentrations, but the persistant low concentrations raises the concern of increased resistance.
8 mg/kg q 7-14 days
Labeled for dogs and cats
Azithromycin is an azalide antimicrobial. In general it can be thought of as being similar to the macrolides (i.e. erythromycin), but with increased antimicrobial activity except against Enterococcus spp. Azithromycin has less vomiting than erythromycin and penetrates lungs and tissues well. Adverse effects can include: nausea, vomiting, diarrhea. The spectrum includes Gram (+), Mycoplasma, Chlamydia, Borellia, Bordetella, and Bartonella. Azithromycin is not cost prohibitive: tablets, 250 mg, cost ~$1-2 per tablet and the suspension 40 mg/mL, 30 mL bottle, costs ~$20.
The ideal dosing has not been established for dogs and cats
The current recommended dosages are:
Dogs: 3-10 mg/kg q 24 h x 3-7 days
Cats: 5 – 10 mg/kg q 24 h x 7 days than q 48 h