Flucloxacillin inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), primarily PBP1, PBP2, and PBP3. This prevents the formation of peptidoglycan, a crucial component of the bacterial cell wall, leading to bacterial cell lysis and death. Its activity is primarily against Gram-positive bacteria.
Pharmacokinetics
Absorption is best when administered on an empty stomach. Peak plasma concentrations are typically reached within 1-2 hours of oral administration. Bioavailability is approximately 40-60% following oral ingestion. Food significantly reduces absorption. Flucloxacillin is extensively bound to plasma proteins (approximately 90%).
Distribution and Excretion
- Flucloxacillin distributes well into most tissues and fluids, except for the cerebrospinal fluid. It is primarily metabolized in the liver, with minimal unchanged drug excreted in the urine. The elimination half-life is approximately 30-60 minutes. Renal impairment minimally alters the pharmacokinetic profile due to non-renal elimination.
Dosage Considerations
Dosage depends on the infection severity and the patient’s renal function. Adjustments may be necessary for patients with hepatic or renal impairment although usually minimal. Standard dosage regimens are available in clinical guidelines. Consult these for specific recommendations.
Drug Interactions
Flucloxacillin may interact with other medications, potentially altering their effectiveness. Concurrent use with drugs that affect liver metabolism, such as rifampin, should be carefully monitored. Always check for drug interactions before prescribing or administering flucloxacillin.
Monitoring
Regular monitoring of clinical response and potential adverse effects are advised. This includes tracking of symptoms, laboratory markers, and organ function.
