ENAFEN 400 TABLETS

Indications

• Skin and soft tissue infections
• Bone infections (osteomyelitis)
• Respiratory tract infections
• Endocarditis
• Infections due to penicillinase-producing staphylococci

Dosage

Children: Refer to the BNF for Children for appropriate dosing guidelines for paediatric patients.

Adults: Refer to the BNF for specific dosage recommendations based on the type and severity of infection.

Mechanism of action

Flucloxacillin exerts its antibacterial effect by inhibiting bacterial cell wall synthesis. It binds to penicillin-binding proteins (PBPs) on the bacterial cell membrane, leading to the disruption of peptidoglycan cross-linking, ultimately resulting in cell lysis and death of the bacteria. This action is particularly effective against actively dividing bacteria.

Pharmacodynamics

The pharmacodynamics of flucloxacillin involves its time-dependent antibacterial activity, with efficacy closely related to the duration of time that plasma concentrations exceed the minimum inhibitory concentration (MIC) for the target organisms. The drug demonstrates a post-antibiotic effect, meaning that bacterial growth remains inhibited even after drug levels decline, particularly in staphylococci.

Pharmacokinetics

Flucloxacillin is well absorbed from the gastrointestinal tract, although food may reduce its absorption. It is widely distributed in body tissues and fluids, achieving therapeutic concentrations in most sites of infection. The drug is primarily excreted unchanged in the urine, with renal function significantly influencing its clearance. The half-life is approximately 1 hour, necessitating multiple dosing to maintain effective levels.

Contra-indications

• Hypersensitivity to flucloxacillin or any penicillin antibiotic
• History of severe allergic reactions to beta-lactam antibiotics

Adverse effects

• Nausea
• Diarrhea
• Rash
• Urticaria
• Angioedema
• Anaphylaxis
• Hepatotoxicity
• Renal impairment

Interactions

• Probenecid may increase serum concentrations of flucloxacillin
• Methotrexate may have increased toxicity when given with flucloxacillin
• Warfarin may have altered anticoagulant effects

Precautions

• Use with caution in patients with a history of gastrointestinal disease, particularly colitis
• Monitor liver function during prolonged therapy
• Assess renal function in patients with existing renal impairment

Pregnancy

Flucloxacillin can be used during pregnancy if clearly needed, as there is limited evidence of harm.

Breast-feeding

Flucloxacillin is excreted in breast milk in small amounts; it is generally considered safe, but monitoring for adverse effects in the infant is advisable.

Storage

Store below 25°C in a cool, dry place. Protect from light. Keep out of reach of children.

Formulations

• Capsules
• Oral suspension
• Injectable form