Usage
Flucloxacillin sodium is a narrow-spectrum beta-lactam antibiotic belonging to the penicillin class. It is prescribed for the treatment of infections caused by Gram-positive bacteria, particularly those producing beta-lactamase, an enzyme that inactivates many penicillins. These organisms include Staphylococcus aureus, Streptococcus pneumoniae, and other streptococci. It is commonly used to treat skin and soft tissue infections (e.g., boils, abscesses, cellulitis), respiratory tract infections (e.g., pneumonia, sinusitis, tonsillitis), and other infections like osteomyelitis, endocarditis, and urinary tract infections. It can also be used as a prophylactic agent during major surgical procedures.
Pharmacological Classification: Antibiotic (Beta-lactam, Penicillin)
Mechanism of Action: Flucloxacillin inhibits bacterial cell wall synthesis by binding to and inactivating penicillin-binding proteins (PBPs). These proteins are essential for cross-linking peptidoglycans, the building blocks of the bacterial cell wall. This disruption weakens the cell wall, leading to bacterial lysis and death. Flucloxacillin is resistant to breakdown by beta-lactamase, making it effective against beta-lactamase-producing strains of bacteria.
Alternate Names
Flucloxacillin is the generic name. There may be slight variations of this name in different countries but Flucloxacillin remains the accepted international nonproprietary name.
Brand Names: Flucloxacillin is marketed under various brand names. Examples include Floxapen, Flubex, Staphlex, and others depending on the geographical location and specific manufacturer.
How It Works
Pharmacodynamics: Flucloxacillin exerts a bactericidal effect by disrupting bacterial cell wall synthesis. It specifically targets Gram-positive bacteria due to their unique cell wall structure. The drug’s beta-lactamase resistance allows it to remain effective against strains that would otherwise inactivate other penicillins.
Pharmacokinetics:
- Absorption: Flucloxacillin is well-absorbed orally, though absorption is enhanced when taken on an empty stomach. Intramuscular and intravenous administration achieve higher serum concentrations.
- Distribution: It is widely distributed throughout the body, including bone, joint fluid, and pleural fluid.
- Metabolism: Flucloxacillin undergoes minimal metabolism in the liver.
- Elimination: Primarily excreted unchanged by the kidneys, with a small amount excreted in bile. Dose adjustment may be needed in patients with renal impairment.
Mode of Action: Flucloxacillin’s mode of action involves irreversible binding to and inhibition of PBPs. This prevents the transpeptidation reaction crucial for peptidoglycan cross-linking, leading to cell wall instability and bacterial death.
Receptor Binding/Enzyme Inhibition: Flucloxacillin primarily targets PBPs, essential bacterial enzymes responsible for cell wall integrity. It acts as a mechanism-based inhibitor, forming a stable covalent bond with the active site of PBPs.
Elimination Pathways: Flucloxacillin is mainly eliminated through renal excretion. Minor biliary excretion also contributes to its elimination.
Dosage
Standard Dosage
Adults:
- Oral: 250-500 mg every 6 hours. Dosage may be doubled in severe infections.
- IM/IV: 250 mg to 1 g every 6 hours. Dosage may be doubled in severe infections.
Children:
- Oral/IM/IV:
- 2-10 years: Half the adult dose.
- Under 2 years: Quarter the adult dose.
- Neonates (under 4 weeks): Flucloxacillin use in this population should be guided by pediatric specialists due to potential risks like jaundice and elevated blood levels of the drug. Other formulations may be more suitable.
- Children aged 10 to 14 years: usually receive a daily dose of 1.5 g to 2 g, divided into three to four equal doses.
- Children aged 6 to 10 years: usually receive a daily dose of 0.75g to 1.5g, divided into three to four equal doses.
Special Cases:
- Elderly Patients: Standard adult dosage is usually appropriate, but renal function should be monitored.
- Patients with Renal Impairment: Dose reduction or extension of the dosing interval may be required in patients with severe renal failure (creatinine clearance < 10 ml/min).
- Patients with Hepatic Dysfunction: Dosage adjustment may not be necessary, but liver function monitoring is advisable during prolonged treatment.
- Patients with Comorbid Conditions: Dosage adjustments may be needed depending on the specific comorbidity.
Clinical Use Cases
Dosing in clinical use cases should be guided by the specific infection being treated, its severity, and patient factors. Consult relevant clinical guidelines and expert opinion for specific recommendations.
- Intubation/Surgical Procedures/Mechanical Ventilation/ICU Use/Emergency Situations: Dosage may need to be adjusted based on the clinical context and severity of the infection. Consult infectious disease specialists and follow institutional guidelines.
Dosage Adjustments
Dose adjustments may be needed based on renal function, hepatic function, and patient response to therapy. Therapeutic drug monitoring might be useful in some cases to optimize drug levels and minimize toxicity.
Side Effects
Common Side Effects:
- Nausea
- Diarrhea
- Indigestion
- Abdominal discomfort
Rare but Serious Side Effects:
- Cholestatic jaundice (hepatitis)
- Interstitial nephritis
- Neutropenia
- Allergic reactions (rash, urticaria, angioedema, anaphylaxis)
- Stevens-Johnson syndrome
- Toxic epidermal necrolysis
Long-Term Effects: With prolonged use, superinfections (such as candidiasis) may occur.
Contraindications
- Hypersensitivity to flucloxacillin, other penicillins, or cephalosporins.
- History of flucloxacillin-associated jaundice or hepatic dysfunction.
Drug Interactions
- Probenecid: Reduces renal excretion of flucloxacillin, increasing serum levels.
- Methotrexate: Flucloxacillin can decrease methotrexate excretion, increasing the risk of methotrexate toxicity.
- Oral Contraceptives: Flucloxacillin may reduce the effectiveness of estrogen-containing oral contraceptives.
- Warfarin: Close monitoring of INR may be necessary.
- Paracetamol: Concurrent use may increase the risk of high anion gap metabolic acidosis, especially in patients with risk factors like renal impairment, sepsis, or malnutrition.
Pregnancy and Breastfeeding
- Pregnancy: Flucloxacillin is generally considered safe to use during pregnancy. However, the decision to use it should be made in consultation with a doctor, weighing the potential benefits against the potential risks.
- Breastfeeding: Flucloxacillin is excreted in breast milk in small amounts. While generally considered safe, monitor the infant for signs of diarrhea or thrush.
Drug Profile Summary
- Mechanism of Action: Inhibits bacterial cell wall synthesis by binding to PBPs.
- Side Effects: Nausea, diarrhea, jaundice (rare), allergic reactions.
- Contraindications: Penicillin or cephalosporin hypersensitivity, history of flucloxacillin-associated jaundice/hepatic dysfunction.
- Drug Interactions: Probenecid, methotrexate, oral contraceptives.
- Pregnancy & Breastfeeding: Generally considered safe, but consult a doctor.
- Dosage: Adults: 250-500 mg PO q6h or 250mg-1g IV/IM q6h; Children: dose adjusted based on age/weight.
- Monitoring Parameters: Liver function tests, renal function tests, signs of hypersensitivity.
Popular Combinations
Flucloxacillin is not typically used in combination with other antibiotics due to its narrow spectrum of activity.
Precautions
- Assess for penicillin allergy before administration.
- Monitor liver and kidney function during prolonged treatment.
- Observe for signs of superinfection (thrush, diarrhea).
- Caution in patients with renal impairment.
- Avoid concurrent use with paracetamol in patients with risk factors for high anion gap metabolic acidosis.
- Use with caution in newborns due to the risk of jaundice.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Flucloxacillin Sodium?
A: Adults: 250-500 mg orally every 6 hours, or 250 mg - 1g IV/IM every 6 hours. Pediatric dosage is adjusted based on age and weight (2-10 years: half the adult dose; under 2 years: quarter the adult dose). Dosage adjustments are needed for renal impairment.
Q2: What are the common side effects of Flucloxacillin?
A: Common side effects include nausea, diarrhea, and indigestion.
Q3: Is Flucloxacillin safe to use during pregnancy?
A: Generally considered safe, but consult a doctor to weigh the potential benefits and risks.
Q4: Can I drink alcohol while taking Flucloxacillin?
A: There are no specific contraindications regarding alcohol consumption while taking Flucloxacillin. However moderation is advised.
Q5: How should Flucloxacillin be administered?
A: Flucloxacillin can be administered orally, intramuscularly, or intravenously. It is important to take oral Flucloxacillin on an empty stomach for optimal absorption.
Q6: What infections is Flucloxacillin typically used to treat?
A: Flucloxacillin is used to treat infections caused by beta-lactamase-producing Gram-positive bacteria, including skin and soft tissue infections, respiratory tract infections, bone infections, and endocarditis.
Q7: What should I do if I miss a dose of Flucloxacillin?
A: If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not double the dose to catch up.
Q8: Are there any drug interactions I should be aware of with Flucloxacillin?
A: Yes, Flucloxacillin interacts with probenecid, methotrexate, and oral contraceptives. Concurrent use with paracetamol should be avoided in certain patient populations. It is important to inform your doctor about all medications you are taking.
Q9: How long does it take for Flucloxacillin to start working?
A: You should start to feel better within a few days of starting Flucloxacillin. However, it is important to complete the full course of treatment as prescribed by your doctor, even if you feel better sooner.
Q10: What should I do if I experience an allergic reaction to Flucloxacillin?
A: Allergic reactions can range from mild skin rashes to severe anaphylaxis. Stop taking the medication immediately and seek urgent medical attention if you experience any signs of an allergic reaction.
