Quofenix: Uses, Dosage & Side Effects
A novel anionic fluoroquinolone antibiotic for acute bacterial skin and skin structure infections and community-acquired bacterial pneumonia, with activity against MRSA and enhanced penetration at acidic pH
Quofenix (delafloxacin) is a novel anionic fluoroquinolone antibiotic authorised for the treatment of acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP) in adults. Unlike most other fluoroquinolones, delafloxacin has balanced affinity for both bacterial DNA gyrase and topoisomerase IV, demonstrates enhanced activity at the acidic pH found in infected tissues and abscesses, and retains activity against methicillin-resistant Staphylococcus aureus (MRSA). Quofenix is administered as a 300 mg intravenous infusion twice daily and may be switched to oral delafloxacin tablets where available. Because of class-wide fluoroquinolone safety concerns, Quofenix is reserved for situations where other commonly recommended antibacterials are considered inappropriate.
Quick Facts: Quofenix
Key Takeaways
- Quofenix (delafloxacin) is an anionic fluoroquinolone antibiotic that inhibits bacterial DNA gyrase and topoisomerase IV with balanced affinity, providing broad Gram-positive, Gram-negative, and anaerobic coverage including methicillin-resistant Staphylococcus aureus (MRSA).
- It is authorised in adults for acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP) when other commonly recommended antibacterials are considered inappropriate.
- The standard dose is 300 mg as an intravenous infusion over 60 minutes every 12 hours, with optional switch to oral delafloxacin 450 mg every 12 hours where available, for a total course of 5–14 days depending on infection.
- Fluoroquinolones including delafloxacin carry serious class-wide safety warnings for tendinitis and tendon rupture, peripheral neuropathy, central nervous system effects, QT prolongation, aortic aneurysm/dissection, and disabling neuromuscular effects – reserve use and stop at first warning sign.
- Quofenix is contraindicated in pregnancy, breastfeeding, and patients with a history of fluoroquinolone-associated tendon disorders; caution is required in myasthenia gravis, epilepsy, severe renal impairment (eGFR < 15 mL/min/1.73 m²), and concurrent QT-prolonging drugs.
What Is Quofenix and What Is It Used For?
Quofenix contains the active substance delafloxacin (as delafloxacin meglumine), a synthetic, broad-spectrum antibacterial belonging to the fluoroquinolone class. Fluoroquinolones act by inhibiting two essential bacterial enzymes – DNA gyrase (bacterial topoisomerase II) and topoisomerase IV – that are required for the winding, unwinding, replication, and repair of bacterial DNA. When these enzymes are blocked, the bacterial chromosome cannot be properly managed during cell division, leading to rapid, concentration-dependent bactericidal killing of susceptible organisms.
What distinguishes delafloxacin from older fluoroquinolones is its chemical structure. Delafloxacin lacks the traditional basic protonated amine group on the C-7 side chain; instead it carries an anionic carboxylate functionality. This makes delafloxacin a weakly acidic molecule that becomes predominantly neutral at acidic pH, dramatically increasing its intracellular accumulation and antibacterial potency in low-pH environments such as infected tissues, abscesses, inflammatory exudates, and phagocytes. Delafloxacin also has unusually balanced inhibitory activity against both DNA gyrase and topoisomerase IV, compared with other fluoroquinolones that typically favour one enzyme – a feature that may help slow the emergence of single-step target-mediated resistance.
Delafloxacin’s in vitro spectrum is broader than most fluoroquinolones. It covers Gram-positive pathogens including methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MSSA and MRSA, including strains with reduced susceptibility to ciprofloxacin), coagulase-negative staphylococci, Streptococcus pyogenes, other beta-haemolytic streptococci, and Streptococcus pneumoniae. It is also active against many Gram-negative organisms including Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Haemophilus influenzae, and Pseudomonas aeruginosa, as well as atypical respiratory pathogens (Legionella pneumophila, Mycoplasma pneumoniae, Chlamydia pneumoniae) and selected anaerobes.
In the European Union, Quofenix is authorised under the trade name Quofenix (marketed by A. Menarini Industrie Farmaceutiche Riunite) for the treatment of the following infections in adults, when it is considered inappropriate to use other antibacterial agents that are commonly recommended for the initial treatment of these infections or when these have failed:
- Acute bacterial skin and skin structure infections (ABSSSI): Including cellulitis, erysipelas, wound infections (surgical and non-surgical), and major cutaneous abscesses. These are infections of the skin or underlying soft tissues that typically cause an area of redness, swelling, warmth, and pain of at least 75 cm², and may be associated with systemic signs of infection such as fever or an elevated white blood cell count.
- Community-acquired bacterial pneumonia (CABP): Bacterial infection of the lungs acquired outside a hospital setting, presenting with cough, sputum production, fever, and changes visible on chest imaging. Delafloxacin covers the typical pathogens (S. pneumoniae, H. influenzae, S. aureus) as well as atypical organisms responsible for CABP.
In the United States, delafloxacin is marketed under the brand name Baxdela and is approved by the U.S. Food and Drug Administration (FDA) for the same two indications in adults. Both the EMA and FDA labels explicitly reserve delafloxacin for situations where other treatment options are not appropriate, in line with the class-wide restriction on systemic fluoroquinolones that reflects their serious and potentially irreversible adverse-reaction profile.
Delafloxacin is included in the World Health Organization (WHO) AWaRe classification within the Watch group of antibiotics, reflecting higher resistance potential and the importance of antibiotic stewardship. Its use should therefore be reserved for specific clinical indications supported by culture and susceptibility data whenever possible, and treatment duration should be the shortest effective duration.
Infected tissue, abscesses, and intracellular environments such as macrophage phagolysosomes are typically acidic (pH around 5.5–6.5). Most older fluoroquinolones are zwitterions or cations at these pH levels, which limits their uptake. Because delafloxacin becomes predominantly neutral at acidic pH, it accumulates more readily at the infection site and within host cells, delivering higher drug concentrations where they are most needed and retaining activity against organisms growing in low-pH biofilms.
What Should You Know Before Receiving Quofenix?
Contraindications
There are specific situations in which Quofenix must not be used. These absolute contraindications reflect either an unacceptable risk of serious harm or known lack of benefit.
- Hypersensitivity: Do not receive Quofenix if you are hypersensitive to delafloxacin, any other fluoroquinolone or quinolone antibacterial (for example ciprofloxacin, levofloxacin, moxifloxacin, ofloxacin, or norfloxacin), or to any of the excipients including meglumine, sulfobutylether beta-cyclodextrin sodium, edetate disodium, sodium hydroxide and hydrochloric acid.
- History of fluoroquinolone-associated tendon disease: Do not use Quofenix if you have a history of tendon disorders related to administration of fluoroquinolone antibacterial agents. The risk of recurrence is high.
- Pregnancy and breastfeeding: Delafloxacin is contraindicated during pregnancy and breastfeeding due to the risk of cartilage damage observed with fluoroquinolones in animal studies and the known neonatal risks of the class.
- Children and adolescents: Quofenix is not recommended in individuals under 18 years of age because fluoroquinolones have been associated with arthropathy and effects on weight-bearing joints in juvenile animal models.
Warnings and Precautions
Systemic fluoroquinolones, including delafloxacin, can cause serious, disabling, and potentially irreversible adverse reactions involving tendons, muscles, joints, peripheral nerves, and the central nervous system, sometimes occurring after only a single dose. Regulatory authorities including the EMA and FDA have restricted fluoroquinolone use to situations where no alternative treatment is suitable. Quofenix should be discontinued at the first sign of any serious adverse reaction such as tendon pain, inflammation, unexplained numbness or tingling, severe headache, or mood changes.
Before and during treatment with Quofenix, inform your doctor if any of the following apply to you. Your medical team will weigh the benefits and risks, monitor you appropriately, and stop treatment if a serious adverse event occurs.
- Tendinitis and tendon rupture: Fluoroquinolones can cause inflammation and rupture of tendons, most commonly the Achilles tendon, but also the rotator cuff, biceps, hand, and other tendons. The risk is increased in patients over 60 years of age, those receiving corticosteroids, organ transplant recipients, and individuals with renal impairment. Tendon rupture can occur during or up to several months after therapy.
- Peripheral neuropathy: Cases of sensory or sensorimotor polyneuropathy, including irreversible cases, have been reported with fluoroquinolones, with symptoms including pain, burning, tingling, numbness, or weakness. Discontinue immediately if symptoms appear and avoid further use of fluoroquinolones.
- Central nervous system effects: Fluoroquinolones may cause convulsions, toxic psychosis, depression, suicidal ideation, anxiety, nightmares, insomnia, tremors, confusion, hallucinations, and increased intracranial pressure. Use with caution in patients with epilepsy, a history of seizures, or other CNS conditions that may predispose to seizures or lower the seizure threshold.
- Aortic aneurysm and dissection: Epidemiological studies have linked fluoroquinolones to an increased risk of aortic aneurysm and dissection, particularly in older adults. Use Quofenix only after careful benefit-risk assessment in patients with known aortic aneurysm or risk factors such as Marfan syndrome, Ehlers-Danlos syndrome, Takayasu arteritis, giant cell arteritis, atherosclerosis, or uncontrolled hypertension.
- Heart valve regurgitation: Fluoroquinolones have been associated with an increased risk of mitral or aortic regurgitation, especially in patients with predisposing conditions such as congenital or pre-existing valvulopathy, connective tissue disorders, hypertension, or older age.
- QT interval prolongation: Fluoroquinolones as a class can prolong the QT interval on the electrocardiogram, which may lead to life-threatening ventricular arrhythmias such as torsades de pointes. Avoid Quofenix in patients with known QT prolongation, uncorrected hypokalaemia or hypomagnesaemia, or concurrent treatment with other QT-prolonging drugs (e.g. class IA or III antiarrhythmics, macrolides, some antipsychotics, tricyclic antidepressants).
- Dysglycaemia: Fluoroquinolones have been associated with disturbances in blood glucose, including hypoglycaemia and hyperglycaemia, often in diabetic patients receiving oral hypoglycaemic agents (such as sulphonylureas) or insulin. Monitor blood glucose carefully.
- Myasthenia gravis: Fluoroquinolones may exacerbate muscle weakness in patients with myasthenia gravis, leading to breathing difficulties or death. Quofenix should be avoided in patients with a known history of myasthenia gravis.
- Clostridioides difficile-associated diarrhoea (CDAD): Antibacterial therapy can disrupt the normal gut flora and allow overgrowth of C. difficile. CDAD has been reported with nearly all antibacterials, ranging from mild diarrhoea to fatal pseudomembranous colitis. Consider this diagnosis in any patient with diarrhoea during or after Quofenix treatment.
- Hypersensitivity and serious skin reactions: Serious hypersensitivity reactions, including anaphylaxis, have been reported with fluoroquinolones, sometimes after the first dose. Serious skin reactions such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reaction with eosinophilia and systemic symptoms (DRESS) have been reported with fluoroquinolones.
- Hepatotoxicity: Elevations in liver enzymes (transaminases) can occur with delafloxacin. Rare cases of severe hepatic dysfunction and acute liver failure have been reported with other fluoroquinolones. Monitor liver function in patients with signs suggestive of hepatotoxicity.
- Renal impairment: Delafloxacin is predominantly eliminated by the kidneys. A dose adjustment is required in patients with severe renal impairment (eGFR 15–29 mL/min/1.73 m²) or end-stage renal disease on haemodialysis, and the intravenous formulation should be avoided in patients with eGFR < 30 mL/min/1.73 m² who are not on haemodialysis because the solubilising excipient sulfobutylether beta-cyclodextrin sodium may accumulate.
- Photosensitivity: Moderate to severe phototoxicity reactions can occur with fluoroquinolones. Avoid prolonged exposure to strong sunlight or UV light and use sun protection during treatment.
- Superinfection: Prolonged use may result in overgrowth of non-susceptible organisms such as yeasts.
Other Medications
Tell your doctor about all medications you are currently taking or have recently taken, including prescription, over-the-counter, herbal products, and dietary supplements. Several important interactions are described in the next section, but of particular note: multivalent cation-containing products (such as antacids with aluminium or magnesium, calcium, iron, zinc, and sucralfate) should not be administered within 2 hours before or 6 hours after oral delafloxacin, as they dramatically reduce absorption. The IV formulation is not affected by this absorption interaction, but the oral switch formulation is.
Pregnancy and Breastfeeding
Quofenix is contraindicated during pregnancy and breastfeeding. There are no adequate data from the use of delafloxacin in pregnant women. Animal studies with fluoroquinolones as a class have shown reproductive toxicity and cartilage damage in juvenile animals. Women of childbearing potential should use effective contraception during treatment with delafloxacin.
It is unknown whether delafloxacin is excreted in human breast milk. A risk to the breastfed infant cannot be excluded, and because of the known fluoroquinolone-class risks to developing cartilage and joints, breastfeeding should be discontinued during treatment with Quofenix.
Driving and Operating Machinery
Quofenix has a moderate influence on the ability to drive and use machines. Patients may experience dizziness, fatigue, or CNS effects such as headache or confusion. Do not drive or operate heavy machinery until you know how Quofenix affects you.
Important Information About Ingredients
Quofenix contains sulfobutylether beta-cyclodextrin sodium as a solubilising excipient. In patients with severe renal impairment (eGFR < 30 mL/min/1.73 m²), cyclodextrins can accumulate, which is why the intravenous formulation is not recommended in this group unless the patient is on haemodialysis. Each 300 mg vial contains approximately 175 mg of sodium (after reconstitution and preparation of the infusion), equivalent to about 8.7% of the WHO recommended maximum daily dietary intake of 2 g sodium for an adult; this should be taken into account in patients on a controlled sodium diet.
How Does Quofenix Interact with Other Drugs?
Delafloxacin does not undergo substantial metabolism by cytochrome P450 enzymes and is neither a significant inhibitor nor inducer of these enzymes at clinical concentrations. As a result, it has fewer pharmacokinetic interactions than some older fluoroquinolones such as ciprofloxacin. However, pharmacodynamic interactions – related to shared toxicities with other drug classes – are clinically important, and a few pharmacokinetic interactions involving absorption or transporters do apply.
Major Interactions
| Interacting Drug | Effect | Clinical Significance |
|---|---|---|
| Warfarin and other oral anticoagulants | Possible potentiation of anticoagulant effect; increased INR and bleeding reported with fluoroquinolones | Monitor INR and signs of bleeding closely during co-administration |
| QT-prolonging drugs (class IA/III antiarrhythmics, macrolides, tricyclic antidepressants, some antipsychotics) | Additive QT interval prolongation, risk of torsades de pointes | Avoid combination where possible; consider ECG monitoring |
| Systemic corticosteroids | Substantially increased risk of tendinitis and tendon rupture | Avoid combination especially in patients > 60 years; counsel on tendon symptoms |
| Multivalent cations (oral antacids with Al/Mg, calcium, iron, zinc, sucralfate, multivitamins with minerals, didanosine buffered tablets) | Chelation markedly decreases absorption of oral delafloxacin | Take oral delafloxacin 2 hours before or 6 hours after these products |
| Oral hypoglycaemics and insulin | Risk of hypoglycaemia or hyperglycaemia, including severe cases | Monitor blood glucose frequently, especially in older adults |
Other Interactions
| Interacting Drug | Effect | Clinical Significance |
|---|---|---|
| Theophylline | Class effect – some fluoroquinolones raise theophylline levels; delafloxacin interaction appears minimal but monitoring advised | Monitor theophylline levels and toxicity (tremor, tachycardia, seizures) |
| NSAIDs | Theoretical additive lowering of seizure threshold | Use with caution in patients with epilepsy or predisposition to seizures |
| Probenecid | May reduce renal elimination of delafloxacin via OAT3 inhibition | Monitor for exaggerated or prolonged effect; dose adjustment may be required |
| Live vaccines (BCG, typhoid, cholera) | Antibacterials may reduce immune response to live bacterial vaccines | Separate administration where feasible |
| Methotrexate | Class effect – fluoroquinolones may decrease renal tubular secretion, raising methotrexate levels | Monitor for methotrexate toxicity (myelosuppression, mucositis) |
The intravenous Quofenix formulation is chemically incompatible with many other intravenous drugs and solutions. It must be diluted only in 0.9% sodium chloride solution or 5% glucose solution, and the line should be flushed before and after infusion when administered through a shared intravenous line. Do not mix Quofenix with other medicinal products in the same infusion container or administer simultaneously through the same line unless compatibility has been established.
What Is the Correct Dosage of Quofenix?
Quofenix is always prescribed and administered by qualified healthcare professionals in a hospital, infusion centre, or other supervised setting. The dose and duration are chosen based on the type and severity of infection, the susceptibility of the causative organism, and your kidney function. Follow the instructions of your treating doctor or infectious-diseases specialist carefully.
Adults
Acute Bacterial Skin and Skin Structure Infections (ABSSSI)
Intravenous: 300 mg delafloxacin infused over 60 minutes every 12 hours
Oral (where available, step-down): 450 mg delafloxacin every 12 hours
Total duration: 5 to 14 days, combining IV and oral therapy as clinically appropriate
Community-Acquired Bacterial Pneumonia (CABP)
Intravenous: 300 mg delafloxacin infused over 60 minutes every 12 hours
Oral (where available, step-down): 450 mg delafloxacin every 12 hours
Total duration: 5 to 10 days, combining IV and oral therapy as clinically appropriate
Patients clinically improving on IV therapy may be switched to oral delafloxacin to complete the total duration.
Patients with Renal Impairment
Delafloxacin is primarily cleared by the kidneys. Dose adjustment is required in significant renal impairment, and the intravenous formulation has specific restrictions because of the cyclodextrin excipient.
| Renal Function (eGFR) | IV Dose | Oral Dose |
|---|---|---|
| ≥ 30 mL/min/1.73 m² (normal to moderate impairment) | 300 mg every 12 hours | 450 mg every 12 hours |
| 15–29 mL/min/1.73 m² (severe impairment) | 200 mg every 12 hours | 450 mg every 12 hours |
| < 15 mL/min/1.73 m² or end-stage renal disease not on haemodialysis | Not recommended | Not recommended |
| Haemodialysis | Not recommended | Not recommended |
Patients with Hepatic Impairment
Delafloxacin is not primarily metabolised by the liver, and pharmacokinetic studies in patients with mild to severe hepatic impairment did not show clinically meaningful changes in exposure. No dose adjustment is required for hepatic impairment. However, monitor liver enzymes if treatment is prolonged or if new hepatic symptoms develop.
Elderly Patients
No dose adjustment based on age alone is required. However, elderly patients (> 65 years) are more likely to have reduced renal function, to be receiving corticosteroids, and to be at higher risk of tendon disorders, aortic aneurysm, and QT prolongation. Assess renal function before prescribing and monitor carefully throughout treatment.
Children and Adolescents
The safety and efficacy of delafloxacin in children and adolescents below 18 years of age have not been established. Quofenix is not recommended in this age group because of the class-wide fluoroquinolone effects on developing cartilage observed in juvenile animal studies.
Missed Dose
If a scheduled IV dose is missed in a hospital setting, the medical team will determine whether to give it as soon as possible or skip it and resume the regular schedule, depending on timing. For oral step-down therapy, if you miss a dose and it is less than 8 hours until your next scheduled dose, skip the missed dose. Otherwise, take it as soon as you remember. Do not take a double dose to make up for a missed one.
Overdose
There is limited experience with delafloxacin overdose. In case of overdose, symptomatic and supportive care should be provided, including ECG monitoring (for QT prolongation), assessment of renal and hepatic function, and monitoring for CNS effects or seizures. Haemodialysis is not expected to significantly remove delafloxacin from the body, although cyclodextrin may be removed.
How Quofenix Is Given
Quofenix is supplied as a sterile powder in a single-use glass vial containing 300 mg of delafloxacin (as meglumine). Before administration, the powder is reconstituted with 10.5 mL of 5% glucose or 0.9% sodium chloride solution to produce a clear yellow to amber solution with a final concentration of 25 mg/mL. The reconstituted solution is then further diluted into an infusion bag containing 5% glucose or 0.9% sodium chloride to a total volume of 250 mL, giving a final delafloxacin concentration of approximately 1.2 mg/mL.
The prepared solution is administered by intravenous infusion over 60 minutes through a dedicated line. It should not be given as an intravenous push or bolus. The line should be flushed with a compatible solution before and after infusion if other drugs are administered through the same line. The reconstituted and diluted infusion should preferably be used immediately; if not, chemical and physical in-use stability has been demonstrated for up to 24 hours at 2–8°C (refrigerated).
Quofenix is a specialist antibacterial. Initiation of treatment is by a physician with experience in treating bacterial infections, usually an infectious-diseases specialist, hospitalist, or emergency-medicine physician. You will be closely monitored during and after infusion for infusion-related reactions, cardiac rhythm, renal function, and signs of serious adverse events.
What Are the Side Effects of Quofenix?
Like all medicines, Quofenix can cause side effects, although not everyone gets them. Many reactions are common to all fluoroquinolones and are listed as class effects in the product information. Your medical team will monitor you closely during treatment and will stop Quofenix and start alternative therapy if a serious adverse reaction is suspected. The frequencies below are based on pooled data from the delafloxacin clinical development programme (including the PROCEED ABSSSI studies and the delafloxacin CABP study) together with post-marketing experience and the general fluoroquinolone class label.
Infusion-Related and Injection-Site Reactions
Because Quofenix is given intravenously, local reactions at or around the cannula site are common. These include pain, redness, swelling, phlebitis (inflammation of the vein), and occasionally a rash. Symptoms usually resolve shortly after the infusion is completed or the cannula is changed. Rarely, true infusion-related hypersensitivity may occur, presenting with flushing, pruritus, chest tightness, shortness of breath, or a fall in blood pressure – the infusion should be slowed or stopped and the event treated appropriately.
Side Effects by Frequency
Very Common
May affect more than 1 in 10 people
- Diarrhoea
- Nausea
Common
May affect up to 1 in 10 people
- Vomiting
- Headache
- Dizziness
- Elevated liver enzymes (transaminases)
- Infusion-site reactions (pain, inflammation, phlebitis)
- Pruritus (itching)
- Rash
- Fungal infection (oral or vaginal candidiasis)
- Insomnia
- Decreased appetite
Uncommon
May affect up to 1 in 100 people
- Hypersensitivity reactions (including urticaria and angioedema)
- Clostridioides difficile colitis or diarrhoea
- Paraesthesia (tingling or numbness)
- Blurred vision
- Tinnitus (ringing in the ears) or vertigo
- Palpitations, tachycardia
- Dyspnoea
- Constipation, abdominal pain, dyspepsia
- Flatulence, dry mouth
- Increased blood creatinine (renal dysfunction)
- Hyperglycaemia or hypoglycaemia
- Arthralgia (joint pain), myalgia (muscle pain)
- Anxiety, abnormal dreams
- Prolonged prothrombin time / INR (with concurrent anticoagulation)
- Eosinophilia, thrombocytopenia
Rare
May affect up to 1 in 1 000 people
- Tendinitis and tendon rupture (most commonly Achilles)
- Peripheral sensorimotor neuropathy (potentially irreversible)
- Seizures
- Psychiatric effects (psychosis, hallucinations, severe depression, suicidal ideation)
- QT interval prolongation, ventricular arrhythmia
- Anaphylactic / anaphylactoid reaction
- Stevens-Johnson syndrome, toxic epidermal necrolysis, DRESS
- Severe hepatotoxicity (including hepatitis and acute liver failure)
- Acute renal failure, interstitial nephritis
- Pancytopenia, haemolytic anaemia, agranulocytosis
- Photosensitivity / phototoxic skin reaction
- Exacerbation of myasthenia gravis
Not Known (Class Effects)
Frequency cannot be estimated; reported with fluoroquinolones as a class
- Aortic aneurysm and aortic dissection
- Mitral and aortic valve regurgitation
- Disabling and potentially irreversible reactions involving multiple body systems (musculoskeletal, neurological, sensory, psychiatric, skin, metabolic)
- Idiopathic intracranial hypertension
- Superinfection with non-susceptible organisms
Stop Quofenix and contact your medical team immediately if you develop any of the following: sudden tendon pain or swelling, new numbness or weakness in the limbs, severe abdominal pain or bloody diarrhoea, fainting or palpitations, a severe skin rash with peeling or blistering, swelling of the face or throat, difficulty breathing, suicidal thoughts or marked mood changes, yellowing of the skin or eyes, or sudden severe chest, back, or abdominal pain.
If you experience any side effects, including those not listed here, tell your doctor, pharmacist, or nurse. Reporting suspected adverse reactions to your national pharmacovigilance authority (e.g. the EMA, the FDA MedWatch program, the MHRA Yellow Card Scheme, or equivalent local system) helps continue monitoring the benefit-risk balance of Quofenix.
How Should Quofenix Be Stored?
Keep this medicine out of the sight and reach of children. Do not use Quofenix after the expiry date which is stated on the vial and carton after EXP. The expiry date refers to the last day of that month.
- Unopened vials: Store below 25°C in the original carton to protect from light. Do not freeze.
- Reconstituted solution (25 mg/mL): Use immediately to prepare the infusion. If storage is necessary, keep at 2–8°C (refrigerated) and protect from light.
- Diluted infusion (1.2 mg/mL in 0.9% sodium chloride or 5% glucose): From a microbiological point of view, the product should be used immediately. Chemical and physical in-use stability has been demonstrated for up to 24 hours at 2–8°C when reconstitution and dilution are performed under validated aseptic conditions.
- Inspection: Before administration, inspect the solution visually. Do not use if you see particles or discoloration beyond the expected clear yellow to amber colour.
Do not throw away any medicines via wastewater or household waste. Quofenix is prepared and administered in hospital and unused medicinal product or waste is disposed of by the healthcare facility in accordance with local requirements for hazardous pharmaceutical waste. These measures help protect the environment and reduce the spread of antimicrobial residues.
What Does Quofenix Contain?
Active Substance
The active substance is delafloxacin, present as delafloxacin meglumine salt. Each vial contains delafloxacin meglumine equivalent to 300 mg of delafloxacin. After reconstitution with 10.5 mL of diluent, each mL of the resulting concentrate contains 25 mg of delafloxacin. After further dilution to 250 mL for infusion, the final concentration is approximately 1.2 mg/mL.
Inactive Ingredients (Excipients)
- Meglumine (as salt former and pH buffer)
- Sulfobutylether beta-cyclodextrin sodium (solubilising agent; relevant to renal-impairment dosing)
- Edetate disodium (chelator/stabiliser)
- Sodium hydroxide (pH adjustment)
- Hydrochloric acid (pH adjustment)
Appearance and Contents of the Pack
Quofenix is supplied as a yellow to brown lyophilised powder (freeze-dried cake) in a clear Type I glass vial closed with a rubber stopper and an aluminium seal with a plastic flip-off cap. After reconstitution, the concentrate is a clear yellow to amber solution essentially free of visible particles. Each pack contains 10 vials of 300 mg.
Marketing Authorisation Holder and Manufacturer
In the European Union, Quofenix is marketed by A. Menarini Industrie Farmaceutiche Riunite S.r.l., based in Florence, Italy. In the United States, delafloxacin is marketed as Baxdela by Melinta Therapeutics. Local distribution, packaging, and manufacturing arrangements may vary by country; consult the locally approved product information or your pharmacist for region-specific details.
Frequently Asked Questions About Quofenix
Quofenix (delafloxacin) is a fluoroquinolone antibiotic authorised in adults for the treatment of acute bacterial skin and skin structure infections (ABSSSI) such as cellulitis, wound infections, and major cutaneous abscesses, and for community-acquired bacterial pneumonia (CABP). It is reserved for situations where other commonly recommended antibacterials are considered inappropriate, in line with the class-wide restriction on systemic fluoroquinolones.
Quofenix is given as an intravenous infusion of 300 mg over 60 minutes every 12 hours by a healthcare professional in a hospital or clinic setting. Once you have responded clinically, your doctor may switch you to oral delafloxacin 450 mg twice daily where an oral formulation is available, to complete a total treatment course of typically 5 to 14 days depending on the infection.
Yes. Like all fluoroquinolones, Quofenix can cause tendinitis and tendon rupture, most commonly of the Achilles tendon, either during treatment or up to several months afterwards. The risk is higher in people over 60 years old, those taking corticosteroids (oral or inhaled at high dose), organ transplant recipients, and people with kidney disease. If you experience pain, swelling, or inflammation in a tendon, stop the medication immediately and contact your doctor. Avoid strenuous physical activity if symptoms appear.
Yes. Delafloxacin, the active ingredient in Quofenix, has clinically meaningful activity against methicillin-resistant Staphylococcus aureus (MRSA), which is unusual among fluoroquinolones. In the pivotal PROCEED ABSSSI phase 3 trials, delafloxacin monotherapy achieved clinical response rates at 48–72 hours comparable to those of vancomycin plus aztreonam in patients with documented MRSA-associated skin and skin structure infections, with a similar safety profile. This activity is one of the features that distinguishes delafloxacin from older fluoroquinolones.
Quofenix must not be used in people with known hypersensitivity to delafloxacin or any other fluoroquinolone, people with a history of tendon disorders linked to a previous quinolone, pregnant or breastfeeding women, or children and adolescents under 18 years of age. Caution is required – and often alternatives should be preferred – in people with myasthenia gravis, a history of seizures or epilepsy, known QT prolongation or heart rhythm disorders, risk factors for aortic aneurysm, severe kidney impairment (eGFR < 30 mL/min/1.73 m²), or diabetes requiring hypoglycaemic treatment.
Both the European Medicines Agency (EMA) and the U.S. Food and Drug Administration (FDA) have issued class-wide safety reviews of systemic fluoroquinolones because of reports of serious, long-lasting, and sometimes irreversible adverse reactions affecting tendons, muscles, joints, peripheral nerves, the central nervous system, heart rhythm, aorta, and heart valves. As a result, regulators recommend that fluoroquinolones – including delafloxacin – should not be used for mild to moderate or self-limiting infections, and should be reserved for situations where other first-line antibiotics cannot be used. This is why Quofenix is positioned as a reserve agent rather than a first-choice antibiotic.
There is no specific pharmacokinetic interaction between delafloxacin and alcohol, but alcohol is generally best avoided during treatment for a bacterial infection. Alcohol can worsen dizziness, headache, nausea, and insomnia, and may contribute to dehydration which affects kidney clearance of the drug. Heavy alcohol use also adds an independent burden on the liver. If you drink alcohol, do so in moderation and discuss any concerns with your doctor or pharmacist.
References
- European Medicines Agency (EMA). Quofenix (delafloxacin) – Summary of Product Characteristics and European Public Assessment Report. Last updated 2025. Available from: EMA EPAR.
- U.S. Food and Drug Administration (FDA). Baxdela (delafloxacin) Prescribing Information. Revised 2024. Available from: FDA Drug Label.
- Pullman J, Gardovskis J, Farley B, et al. Efficacy and safety of delafloxacin compared with vancomycin plus aztreonam for acute bacterial skin and skin structure infections: a Phase 3, double-blind, randomized study. J Antimicrob Chemother. 2017;72(12):3471–3480. doi:10.1093/jac/dkx329.
- O’Riordan W, McManus A, Teras J, et al. A comparison of the efficacy and safety of intravenous followed by oral delafloxacin with vancomycin plus aztreonam for the treatment of acute bacterial skin and skin structure infections: a Phase 3, multinational, double-blind, randomized study. Clin Infect Dis. 2018;67(5):657–666. doi:10.1093/cid/ciy165.
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