Mechanism of Action
Cephalosporins inhibit bacterial growth by interfering with bacterial cell wall synthesis. This consists of peptidoglycan, a polymer containing amino sugar (N-acetylglucosamine and N-acetylmuramic acid). Cephalosporins, such as penicillins, bind to the transpeptidase, as they are structural analogues of the substrate of this enzyme, ie the dimer D-Ala-D-Ala (Alanine 2) that serves to create crosslinks between chains of peptidoglycan. The inhibition of transpeptidase blocks the construction of the bacterial cell wall, killing the bacterial cells growing.
Features and applications
The spectrum Cephalosporins have a bit wider penicillin, acting both on Gram + and Gram-on – and are resistant to most beta-lactamases, but are less powerful.
First-generation Cephalosporins (cefazolin, cephalexin, cephalosporin C, cefadroxil, cephapirin, cephalothin) are only active against Gram +, mainly against pneumococci, staphylococci and streptococci. They are all oral administration, and are rarely considered for systemic infection, considering also their lack of power.
The second-generation Cephalosporins (cefamandole, cefaclor, cefonicid, cefprozil, cefoxitin) has greater activity against Gram -, and oral or parenteral administration.
The third generation (cefotaxime, ceftazidime, cefoperazone, ceftriaxone, Suprax, ceftibuten) is administered intravenously, significantly active against infections by Gram – and capable of overcoming the blood-brain barrier. Some of them (ceftriaxone and Suprax) are used against gonorrhea.
A fourth generation cephalosporin (Cefepima) is very similar to those of the third generation of characters but with greater resistance to the lactamase.
Pharmacokinetics of Suprax Pills
The absorption of an oral or intravenous cephalosporins, are also coming into the brain, especially those of 3 generation (used against meningitis).
Are excreted as such (they are not metabolized in the liver) primarily by the kidney, except those of 3 generation are excreted primarily in the bile.
Often using combinations with probenicid (to inhibit the renal tubular secretion and increase the half-life for generations 1,2 and 4) or in association with ß-lactamase inhibitors such as clavulanic acid, sulbactam, or tazobactam.
Side Effects and Warnings
Antibiotics are among the least toxic, most of the adverse reactions in fact regards individual hypersensitivity reactions such as allergies from penicilloic acid (a product of the degradation of these drugs) that occur with rashes or fevers. In rare cases, you can get to anaphylactic shock.
Prolonged use or high doses can also cause kidney damage and depletion of intestinal flora, resulting in intestinal superinfection by opportunistic micro-organisms resistant to the antibiotic.
Should never be taken in combination with ethanol, as they can lead to a disulfiram-like effect (inhibition of aledeide dehydrogenase which involves, after intake of ethanol, an increase of acetaldehyde and symptoms such as nausea, vomiting, flushing, hypotension, headache).