Xacil Mechanism of Action

Pharmacotherapeutic group: Beta-lactamase-resistant penicillins. ATC code: J01CF02-Cloxacillin.
Pharmacology: Pharmacodynamics: Mechanism of action: Cloxacillin belongs to a group of isoxazolyl penicillins combining activity against beta-lactamase-producing staphylococci with acid stability. Cloxacillin inhibits bacterial cell wall synthesis. The effect is bactericidal. Cloxacillin exerts a bacterial action against susceptible microorganisms during the stage of active multiplication. Cloxacillin displays less intrinsic antibacterial activity and a narrower spectrum than penicillin G.
Antibacterial spectrum: (See Table 1.)

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Resistance is common (approximately 40%) in coagulase-negative staphylococci due to methicillin resistance. Streptococci and pneumococci are more sensitive to benzylpenicillin and phenoxymethylpenicillin (penicillin V) compared to cloxacillin.
Mechanism of resistance: Resistance against isoxazolyl penicillins (methicillin resistance) is caused by the production of an altered penicillin-binding protein in bacteria. Cross resistance occurs within the beta-lactam group (penicillins and cephalosporins). In general, methicillin-resistant staphylococci show low sensitivity to all beta-lactam antibiotics.
Pharmacokinetics: Absorption: Absorption is more complete when intramuscular injection is administered, and maximum plasma concentration of approximately 15 ug/mL is reached 30 minutes after a dose of 500 mg. Protein binding: 92%.
Distribution: Provides good concentration in synovial fluid, urine, and gall bladder. Therapeutic serum concentration level of approximately 1 µg/ml (2.1 µmol/L) is kept for about 4 hours.
Biotransformation: Half-life in serum is approximately 30 minutes.
Elimination: Within 6 hours 30-50% of the oral dose is excreted in the urine. 10% is secreted as active metabolites in the urine.