Clavulanic acid

Chemical formula: C₈H₉NOâ‚…  Molecular mass: 199.161 g/mol  PubChem compound: 5280980

Pharmacodynamic properties

Clavulanic acid is a beta-lactam structurally related to penicillins. It inactivates some beta-lactamase enzymes thereby preventing inactivation of amoxicillin. Clavulanic acid alone does not exert a clinically useful antibacterial effect.

The main mechanism of resistance to clavulanic acid is inactivation by those bacterial beta-lactamases that are not themselves inhibited by clavulanic acid, including class B, C and D.

Pharmacokinetic properties

Absorption

Clavulanic acid is fully dissociated in aqueous solution at physiological pH. It is rapidly and well absorbed by the oral route of administration. Following oral administration, clavulanic acid is approximately 70% bioavailable. The time to peak plasma concentration (Tmax) is approximately one hour.

Distribution

About 25% of total plasma clavulanic acid is bound to protein. The apparent volume of distribution is around 0.2 l/kg for clavulanic acid.

Following intravenous administration, clavulanic acid has been found in gall bladder, abdominal tissue, skin, fat, muscle tissues, synovial and peritoneal fluids, bile and pus.

From animal studies there is no evidence for significant tissue retention of drug-derived material for clavulanic acid. Trace quantities of clavulanic acid can be detected in breast milk.

Clavulanic acid has been shown to cross the placental barrier.

Biotransformation

Clavulanic acid is extensively metabolized in man and eliminated in urine and faeces, and as carbon dioxide in expired air.

Elimination

The major route of elimination for clavulanic acid it is by both renal and non-renal mechanisms.

Clavulanic acid has a mean elimination half-life of approximately one hour and a mean total clearance of approximately 25 l/h in healthy subjects. Approximately 40 to 65% of the clavulanic acid are excreted unchanged in urine during the first 6 h after administration of 125 mg tablets. Various studies have found the urinary excretion to be between 27-60% for clavulanic acid over a 24 hour period. In the case of clavulanic acid, the largest amount of drug is excreted during the first 2 hours after administration.

Gender

Following oral administration of clavulanic acid to healthy males and female subjects, gender has no significant impact on the pharmacokinetics of clavulanic acid.

Renal impairment

The total serum clearance of clavulanic acid decreases proportionately with decreasing renal function. Doses in renal impairment must maintain adequate levels of clavulanic acid.

Hepatic impairment

Hepatically impaired patients should be dosed with caution and hepatic function monitored at regular intervals.

Preclinical safety data

Non-clinical data reveal no special hazard for humans based on studies of safety pharmacology, genotoxicity and toxicity to reproduction.

Carcinogenicity studies have not been conducted with clavulanic acid.

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