Container of 250 tablets and blister packs of 140 tablets.
Further Information
Cefalexin, first generation cephalosporin, inhibits bacterial cell wall synthesis in a manner similar to the penicillins, and is widely considered to be bacteriocidal in action. It is thought that cephalexins act by binding to and inactivating a number of different penicillin-binding proteins (PBPs) located on the inner aspects of the bacterial cell membrane. Cephalosporins are essentially time-dependent antibiotics.
Cefalexin is active against a large spectrum of gram-positive and gram-negative bacteria. The breakpoints for cefalexin are usually defined as S≤ 8 μg/ml, R> 32 μg/ml.
The in vitro activity of cefalexin against bacterial isolates from skin infections in dogs is as follows:
Pathogen | MIC90 (µg/ml) |
S. intermedius | 0.5 to 8 |
S. aureus | 2 to 8 |
E. coli | 2 to 16 |
Beta haemolytic Streptococcus spp. | 2 |
The MIC90 value of cefalexin against Klebsiella pneumoniae isolated from urinary tract infections in dogs is 4 µg/ml.
The most prevalent resistance mechanism among gram-negative bacteria to cefalexin is due to the production of various beta-lactamases (cephalosporinase) that cause inactivation. Resistance in gram-positive bacteria often involves a decreased affinity of the PBPs (penicillin-binding proteins) for beta-lactam drugs. Efflux pumps, extruding the antibiotic from the bacterial cell, and structural changes in porins (reducing passive diffusion of the drug through the cell wall), may contribute to bacterial resistance.
Cross-resistance (involving the same resistance mechanism) exists between antibiotics belonging to the beta-lactam group due to their similar structures. This occurs with beta-lactamase enzymes, structural changes in porins or variations in efflux pumps. Co-resistance (involving different resistance mechanisms) has been reported in E. coli due to a plasmid with resistance genes.
After oral administration, 60 to 80% of cefalexin is absorbed from the small intestine. The delay reported between administration and beginning of absorption is approximately 20 minutes and differences in mean AUC, Cmax, and Tmax are not significantly affected by food administration concomitant to treatment with cefalexin.
Dose administered (mg/kg) | 15 |
Cmax (µg/ml) | 17.6 |
Tmax (min) | 158 |
AUC (µg.h/ml) | 73.5 |
Half life (min) | 107 |
Protein binding is low at 18%. Cefalexin is widely distributed into a variety of tissue fluids, including bile, synovial and pericardial fluid. The passage into interstitial tissue, as demonstrated in wound fluid concentration, peritoneal fluid and skin blisters is generally good.
Cefalexin is minimally metabolized and primarily excreted via the renal route, around 70% of an oral dose is excreted into the urine in 24 hours in the dog. It is important to note that cefalexin concentrations obtained in urine are well above plasma concentrations, and similarly concentrations in bile may be up to four times higher.