Formulary
Flucloxacillin: Indications, Dosing, Side Effects and Interactions
The penicillins are bactericidal and act by interfering with bacterial cell wall synthesis.
MedNext Academy | 9 min read
Flucloxacillin: Indications, Dosing, Side Effects and Interactions
The penicillins are bactericidal and act by interfering with bacterial cell wall synthesis.
Drug action
The penicillins are bactericidal and act by interfering with bacterial cell wall synthesis. They diffuse well into body tissues and fluids, but penetration into the cerebrospinal fluid is poor except when the meninges are inflamed. They are excreted in the urine in therapeutic concentrations.
Indications and dose
**Infections due to beta-lactamase-producing staphylococci including otitis externa,Adjunct in pneumonia**
- **Child** (By Mouth): 10-17 years 250-500 mg 4 times a day.
- **Adult** (By Mouth): 250-500 mg 4 times a day.
- **Adult** (By Intramuscular Injection): 250-500 mg every 6 hours.
- **Adult** (By Slow Intravenous Injection, Or By Intravenous Infusion): 0.25-2 g every 6 hours.
**Impetigo**
- **Child** (By Mouth): 10-17 years 250-500 mg 4 times a day for 5-7 days.
- **Adult** (By Mouth): 500 mg 4 times a day for 5-7 days.
- **Adult** (By Intramuscular Injection): 250-500 mg every 6 hours.
- **Adult** (By Slow Intravenous Injection, Or By Intravenous Infusion): 0.25-2 g every 6 hours.
**Cellulitis,Erysipelas**
- **Child** (By Mouth): 10-17 years 250-500 mg 4 times a day for 5-7 days then review.
- **Adult** (By Mouth): 0.5-1 g 4 times a day for 5-7 days then review.
- **Adult** (By Slow Intravenous Injection, Or By Intravenous Infusion): 1-2 g every 6 hours.
**Secondary bacterial infection of eczema**
- **Child** (By Mouth): 10-17 years 250-500 mg 4 times a day for 5-7 days.
- **Adult** (By Mouth): 500 mg 4 times a day for 5-7 days.
**Mild diabetic foot infection**
- **Adult** (By Mouth): 0.5-1 g 4 times a day for 7 days then review.
**Moderate diabetic foot infection,Severe diabetic foot infection**
- **Adult** (By Mouth): 1 g 4 times a day.
- **Adult** (By Slow Intravenous Injection, Or By Intravenous Infusion): 1-2 g every 6 hours.
**Leg ulcer infection**
- **Adult** (By Mouth): 0.5-1 g 4 times a day for 7 days.
- **Adult** (By Slow Intravenous Injection, Or By Intravenous Infusion): 1-2 g every 6 hours.
**Endocarditis (in combination with other antibacterial if necessary)**
- **Adult** (By Slow Intravenous Injection, Or By Intravenous Infusion): (body-weight 85 kg and above) 12 g daily in 6 divided doses.
**Osteomyelitis**
- **Adult** (By Slow Intravenous Injection, Or By Intravenous Infusion): Up to 8 g daily in 3-4 divided doses.
**Staphylococcal lung infection in cystic fibrosis**
- **Child** (By Mouth): (body-weight 40 kg and above) 1 g 4 times a day, alternatively 4 g daily in 3 divided doses.
**Prevention ofStaphylococcus aureuslung infection in cystic fibrosis-primary prevention**
- **Child** (By Mouth): Prevention of Staphylococcus aureus lung infection in cystic fibrosis-primary prevention 1 month-3 years 125 mg twice daily.
**Prevention ofStaphylococcus aureuslung infection in cystic fibrosis-secondary prevention**
- **Child** (By Mouth): Prevention of Staphylococcus aureus lung infection in cystic fibrosis-secondary prevention 50 mg/kg twice daily (max. per dose 1 g).
**Infections due to beta-lactamase-producing staphylococci including otitis externa, Adjunct in pneumonia for flucloxacillin**
- **Neonate up to 7 days** (By mouth): 25 mg/kg twice daily.
- **Neonate 7 days to 20 days** (By mouth): 25 mg/kg 3 times a day.
- **Neonate 21 days to 28 days** (By mouth): 25 mg/kg 4 times a day.
- **Child 1 month-1 year** (By mouth): 62.5-125 mg 4 times a day.
- **Child 2-9 years** (By mouth): 125-250 mg 4 times a day.
- **Child 10-17 years** (By mouth): 250-500 mg 4 times a day.
- **Child** (By intramuscular injection): 12.5-25 mg/kg every 6 hours (max. per dose 500 mg).
- **Neonate up to 7 days** (By slow intravenous injection, or by intravenous infusion): 25 mg/kg every 12 hours.
- **Neonate 7 days to 20 days** (By slow intravenous injection, or by intravenous infusion): 25 mg/kg every 8 hours.
- **Neonate 21 days to 28 days** (By slow intravenous injection, or by intravenous infusion): 25 mg/kg every 6 hours.
- **Child** (By slow intravenous injection, or by intravenous infusion): 12.5-25 mg/kg every 6 hours (max. per dose 1 g).
**Impetigo for flucloxacillin**
- **Neonate up to 7 days** (By mouth): 25 mg/kg twice daily.
- **Neonate 7 days to 20 days** (By mouth): 25 mg/kg 3 times a day.
- **Neonate 21 days to 28 days** (By mouth): 25 mg/kg 4 times a day.
- **Child 1 month-1 year** (By mouth): 62.5-125 mg 4 times a day for 5-7 days.
- **Child 2-9 years** (By mouth): 125-250 mg 4 times a day for 5-7 days.
- **Child 10-17 years** (By mouth): 250-500 mg 4 times a day for 5-7 days.
- **Child** (By intramuscular injection): 12.5-25 mg/kg every 6 hours (max. per dose 500 mg).
- **Neonate up to 7 days** (By slow intravenous injection, or by intravenous infusion): 25 mg/kg every 12 hours.
- **Neonate 7 days to 20 days** (By slow intravenous injection, or by intravenous infusion): 25 mg/kg every 8 hours.
- **Neonate 21 days to 28 days** (By slow intravenous injection, or by intravenous infusion): 25 mg/kg every 6 hours.
- **Child** (By slow intravenous injection, or by intravenous infusion): 12.5-25 mg/kg every 6 hours (max. per dose 1 g).
**Severe infections due to beta-lactamase-producing staphylococci including otitis externa, Adjunct in pneumonia (severe infection), Adjunct in impetigo (severe infection) for flucloxacillin**
- **Neonate up to 7 days** (By slow intravenous injection, or by intravenous infusion): 50 mg/kg every 12 hours.
- **Neonate 7 days to 20 days** (By slow intravenous injection, or by intravenous infusion): 50 mg/kg every 8 hours.
- **Neonate 21 days to 28 days** (By slow intravenous injection, or by intravenous infusion): 50 mg/kg every 6 hours.
- **Child** (By slow intravenous injection, or by intravenous infusion): 25-50 mg/kg every 6 hours (max. per dose 2 g).
**Cellulitis, Erysipelas for flucloxacillin**
- **Child 1 month-1 year** (By mouth): 62.5-125 mg 4 times a day for 5-7 days then review.
- **Child 2-9 years** (By mouth): 125-250 mg 4 times a day for 5-7 days then review.
- **Child 10-17 years** (By mouth): 250-500 mg 4 times a day for 5-7 days then review.
- **Child** (By slow intravenous injection, or by intravenous infusion): 12.5-25 mg/kg every 6 hours (max. per dose 1 g).
**Secondary bacterial infection of eczema for flucloxacillin**
- **Child 1 month-1 year** (By mouth): 62.5-125 mg 4 times a day for 5-7 days.
- **Child 2-9 years** (By mouth): 125-250 mg 4 times a day for 5-7 days.
- **Child 10-17 years** (By mouth): 250-500 mg 4 times a day for 5-7 days.
**Endocarditis (in combination with other antibacterial if necessary) for flucloxacillin**
- **Child** (By slow intravenous injection, or by intravenous infusion): 50 mg/kg every 6 hours (max. per dose 2 g).
**Osteomyelitis for flucloxacillin**
- **Neonate up to 7 days** (By slow intravenous injection, or by intravenous infusion): 50-100 mg/kg every 12 hours.
- **Neonate 7 days to 20 days** (By slow intravenous injection, or by intravenous infusion): 50-100 mg/kg every 8 hours.
- **Neonate 21 days to 28 days** (By slow intravenous injection, or by intravenous infusion): 50-100 mg/kg every 6 hours.
- **Child** (By slow intravenous injection, or by intravenous infusion): 50 mg/kg every 6 hours (max. per dose 2 g).
**Cerebral abscess, Staphylococcal meningitis for flucloxacillin**
- **Neonate up to 7 days** (By slow intravenous injection, or by intravenous infusion): 50-100 mg/kg every 12 hours.
- **Neonate 7 days to 20 days** (By slow intravenous injection, or by intravenous infusion): 50-100 mg/kg every 8 hours.
- **Neonate 21 days to 28 days** (By slow intravenous injection, or by intravenous infusion): 50-100 mg/kg every 6 hours.
- **Child** (By slow intravenous injection, or by intravenous infusion): 50 mg/kg every 6 hours (max. per dose 2 g).
**Staphylococcal lung infection in cystic fibrosis for flucloxacillin**
- **Child (body-weight up to 40 kg)** (By mouth): 25 mg/kg 4 times a day, alternatively 100 mg/kg daily in 3 divided doses.
- **Child (body-weight 40 kg and above)** (By mouth): 1 g 4 times a day, alternatively 4 g daily in 3 divided doses.
- **Child** (By slow intravenous injection, or by intravenous infusion): 50 mg/kg every 6 hours (max. per dose 2 g).
**Prevention of Staphylococcus aureus lung infection in cystic fibrosis-primary prevention for flucloxacillin**
- **Neonate** (By mouth): 125 mg twice daily.
- **Child 1 month-3 years** (By mouth): 125 mg twice daily.
**Prevention of Staphylococcus aureus lung infection in cystic fibrosis-secondary prevention for flucloxacillin**
- **Child** (By mouth): 50 mg/kg twice daily (max. per dose 1 g).
Cautions
History of allergy Cautions For flucloxacillin With intravenous use Accumulation of electrolytes can occur with high doses
Side effects
Common or very common Diarrhoea; hypersensitivity; nausea; skin reactions; thrombocytopenia; vomiting Uncommon Arthralgia; leucopenia Rare or very rare Agranulocytosis; angioedema; haemolytic anaemia; hepatic disorders; nephritis tubulointerstitial; neutropenia; pseudomembranous enterocolitis; seizure; severe cutaneous adverse reactions (SCARs) Side-effects, further information Diarrhoea frequently occurs during oral penicillin therapy. It is most common with broad-spectrum penicillins, which can cause antibiotic-associated colitis. Side-effects For flucloxacillin General side-effects: Rare or very rare Fever; myalgia Specific side-effects: Common or very common With oral use Gastrointestinal disorders Rare or very rare With oral use Eosinophilia Frequency not known With oral use Hypokalaemia; oesophageal disorder; oral pain; oropharyngeal pain; throat irritation With parenteral use Bronchospasm; coma; dyspnoea; electrolyte imbalance; erythema nodosum; hallucination; Jarisch-Herxheimer reaction; nephropathy; neurotoxicity; oral candidiasis; platelet dysfunction; purpura non-thrombocytopenic; vasculitis Side-effects, further information Potentially life-threatening hypokalaemia can occur, especially in high doses. This can be resistant to potassium supplementation. Regular monitoring of serum potassium levels is recommended when using higher doses of flucloxacillin.
Interactions
**Other interactions (9):**
- If concomitant use of CYP2D6 inhibitors and dextromethorphan is necessary, the patient should be monitored and the dextromethorphan dose may need to be reduced Flucloxacillin Caution should be taken...
- Caution should be taken when paracetamol is used concomitantly with flucloxacillin as concurrent intake has been associated with high anion gap metabolic acidosis due to pyroglutamic acidosis,...
- Flucloxacillin Flucloxacillin (a CYP450 inducer) may decrease plasma posaconazole concentrations.
- Concomitant use of posaconazole and flucloxacillin should be avoided unless the benefit to the patient outweighs the risk (see section 4.4).
- If concomitant administration of voriconazole with flucloxacillin cannot be avoided, monitor for potential loss of voriconazole effectiveness (e.g., by therapeutic drug monitoring); increasing the...
- Moderate CYP3A4 inducers: metamizole, phenobarbital, isoniazid, rifabutin, efavirenz, etravirine, nevirapine; weak CYP3A4 inducers: flucloxacillin May decrease tacrolimus whole blood trough...
Pregnancy
Not known to be harmful.
Breast feeding
Trace amounts in milk, but appropriate to use.
Hepatic impairment
Manufacturer advises caution; including in those with risk factors for hepatic reactions.
Renal impairment
Accumulation of sodium from injection can occur in patients with renal failure. With intravenous use: High doses may cause nephrotoxicity or neurotoxicity. Dose adjustments See Prescribing in renal impairment . In adults: Reduce dose or increase dose interval if creatinine clearance less than 10 mL/minute (consult product literature). M In children: Expert sources advise use normal dose every 8 hours if estimated glomerular filtration rate less than 10 mL/minute/1.73 m 2 .
Medicinal forms
Capsule,Solution,Solution
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
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