Pharmacological properties : תכונות פרמקולוגיות

Pharmacodynamic Properties

5.1.   Pharmacodynamic properties
Pharmacotherapeutic group: Beta-lactamase resistant penicillin’s, Antibacterials for systemic use.
ATC code: J01CF02

Cloxacillin is an antibacterial antibiotics of the beta-lactam family of the penicillin M group.
Spectrum of antibacterial activity
Critical concentrations separate the sensitive strains from the strains with intermediate sensitivity and the latter from the resistant ones:
Oxacillin (staphylococcus): S ≤ 2 mg/l and R > 2 mg/l


The prevalence of acquired resistance may vary according to geography and the weather for certain species. It is therefore useful to have information on local resistance prevalence, especially for the treatment of severe infections. These data can only give an indication about the probability of a bacterial starin’s sensitivity to this antibiotic.

Pharmacokinetic Properties

5.2.   Pharmacokinetic properties
Absorption
Cloxacillin is stable in gastric environment. It is well absorbed by the digestive mucous (70%).

Distribution
-         After oral administration, maximum blood concentrations are obtained after 1 hour and are proportional to the administered dose. They are in order of 9 mg/l for one dose of 500 mg.


-         After intramuscular injection, maximum blood concentrations are obtained after about 45 minutes. In adults, they are 26 mg/l for one dose of 1g, 15 mg/l for one dose of 500 mg and 8 mg/l for one dose of 250 mg.
-       After intravenous injection of 2g perfused for 20 minutes, the value of serum peak obtained at the end of the perfusion is 280 mg/l.
-       Half-life is in the order of 45 minutes in patients with normal renal functions.
-       Plasma protein bounding is in the order of 90%.
-       The product diffuses the foetal blood, synovial liquid and bone tissue into the amniotic fluid.

Biotransformation
Cloxacillin is metabolized to a limited extent.

Elimination
After oral administration, the non-absorbed fraction is eliminated by the intestinal route in an inactive form. The absorbed fraction is eliminated in an active form essentially through urine and for 10% through the bile duct.
After administration by injection, the elimination is:
-Urinary, in an active form, in 6 hours, approximately 70 to 80% of the injected dose - Biliary, in an active form, 20 to 30% of the injected dose.