Daptomycin

Daptomycin injection is an IV antibiotic used to treat serious infections caused by Gram-positive bacteria. Specific approvals vary by product and patient age.

• Complicated skin and skin structure infections (cSSSI) — in adults and, for most products, in children aged 1–17 years — caused by bacteria including MRSA, Streptococcus species, and vancomycin-susceptible Enterococcus faecalis
• Staphylococcus aureus bloodstream infections (bacteremia) in adults, including those with right-sided infective endocarditis — supported by Daptomycin in Sodium Chloride Injection, Dapzura RT, and Daptomycin for Injection
• Staphylococcus aureus bloodstream infections in pediatric patients aged 1–17 years — supported by Daptomycin in Sodium Chloride Injection, Dapzura RT, and daptomycin for injection (suspension)
• Not approved for pneumonia, left-sided infective endocarditis due to S. aureus, or use in infants younger than 1 year
• Daptomycin in Sodium Chloride Injection is not indicated for pediatric patients with renal impairment

Daptomycin binds directly to the outer membrane of Gram-positive bacterial cells and rapidly disrupts the electrical charge (membrane potential) across that membrane. This disruption shuts down the bacteria's ability to synthesize DNA, RNA, and proteins — the essential building blocks they need to survive — leading to bacterial cell death. Because this mechanism targets the bacterial cell membrane rather than processes shared with human cells, daptomycin is effective against a range of dangerous Gram-positive organisms, including MRSA.

Daptomycin's killing activity appears to be related to how much drug the bacteria are exposed to over time (expressed as the AUC/MIC ratio), rather than simply peak concentration. It should not be used for pneumonia because a substance in lung fluid (surfactant) inactivates daptomycin.

Daptomycin is given exclusively by intravenous (IV) route — into a vein — once every 24 hours in a hospital or clinical setting. Depending on the product, it may be administered as a 30-minute infusion or a 2-minute IV injection. The duration of treatment varies by indication: skin infections are typically treated for 7–14 days, while bloodstream infections may require 2–6 weeks.

• Dapzura RT is given IV in 0.9% sodium chloride either over 2 minutes or 30 minutes, once daily
• Dosing is adjusted for patients with reduced kidney function (creatinine clearance below 30 mL/min)
• Daptomycin in Sodium Chloride Injection is available only in fixed strengths; it should not be used when a dose that does not equal an available strength is required

The most common side effects reported during daptomycin treatment include:

• Diarrhea
• Headache and dizziness
• Skin rash or itching
• Elevated CPK (a blood marker of muscle stress)
• Nausea, vomiting, or abdominal pain
• Fever (pyrexia)
• High blood pressure or low blood pressure
• Shortness of breath (dyspnea)

Serious reactions to act on right away include severe muscle pain or weakness, breathing difficulty, signs of a severe allergic reaction, new or worsening kidney problems, numbness or tingling in the limbs, and severe or persistent diarrhea — all of which require prompt medical evaluation.

• Myopathy and rhabdomyolysis: Daptomycin can cause serious muscle injury. CPK (a muscle enzyme) is monitored weekly — or more often in patients with kidney problems or those also taking statins. Report any new muscle pain, weakness, or tenderness immediately.
• Eosinophilic pneumonia: A rare lung reaction has occurred, typically 2–4 weeks into treatment, causing fever, breathing difficulty, and low oxygen. Daptomycin must be stopped and steroid treatment started if this occurs.
• Severe allergic reactions (anaphylaxis): Life-threatening allergic reactions have been reported. The drug must be stopped immediately and emergency treatment given.
• DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms): A rare but serious reaction involving skin rash, fever, elevated white blood cell count, and organ involvement. Stop daptomycin promptly if suspected.
• Tubulointerstitial nephritis (TIN): Kidney inflammation has been reported; any new or worsening kidney problems should trigger prompt evaluation.
• Peripheral neuropathy: Numbness, tingling, or weakness in the hands or feet have been reported; monitor for these symptoms.
• C. difficile–associated diarrhea (CDAD): Like all antibiotics, daptomycin can disrupt gut bacteria and allow C. difficile to overgrow, causing diarrhea ranging from mild to life-threatening — even weeks after treatment ends.
• Hereditary Fructose Intolerance (HFI): Dapzura RT contains sorbitol and is contraindicated in patients with known or suspected HFI, as it can trigger a dangerous metabolic crisis.
• Infants under 1 year: All daptomycin injection products should be avoided in this age group due to potential effects on the muscular and nervous systems observed in animal studies.

Daptomycin has a few important interactions to know about:

• Statins (HMG-CoA reductase inhibitors, e.g., simvastatin, atorvastatin): Both statins and daptomycin can stress muscles. Using them together raises the risk of myopathy. Your doctor may pause your statin temporarily while you are on daptomycin.
• PT/INR blood clotting tests: Daptomycin can interfere with certain lab reagents used to measure clotting time (PT and INR), causing falsely high results. Tell your lab team you are receiving daptomycin so they can time the test correctly or use an alternative method if needed.

This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.

• Do not use daptomycin if you have a known allergy (hypersensitivity) to it — this is a contraindication
• Do not use Dapzura RT if you have known or suspected Hereditary Fructose Intolerance (HFI) — it contains sorbitol, which can cause serious harm in people with HFI
• Tell your doctor if you have reduced kidney function — dose adjustments and more frequent monitoring are needed
• Tell your doctor if you take a statin (cholesterol medication) — temporary suspension may be recommended
• Daptomycin injection should not be used in infants younger than 1 year — potential risks to the muscles and nervous system have been seen in animal studies
• Older adults (65+) may have lower treatment success rates; kidney function should be monitored closely
• Pregnancy: limited human data are available; discuss risks and benefits with your doctor
• Breastfeeding: daptomycin is present in human milk in small amounts; discuss with your doctor whether to continue breastfeeding
• Daptomycin in Sodium Chloride Injection is not indicated for pediatric patients with renal impairment because dosing has not been established in that group

If too much daptomycin is given, supportive care is the main approach — keeping the kidneys filtering properly is the priority. Daptomycin is cleared slowly by dialysis: about 15% of a dose is removed in 4 hours by hemodialysis, and about 11% over 48 hours by peritoneal dialysis. Using high-flux dialysis membranes can remove a somewhat larger fraction than standard low-flux membranes.

Daptomycin's antibacterial effect appears to be driven by the total drug exposure over time relative to the minimum amount needed to inhibit bacterial growth — a relationship pharmacologists call the AUC/MIC ratio. This means maintaining adequate drug levels throughout the dosing period matters for effectiveness. Daptomycin is dosed once daily, and animal infection models support this exposure-dependent activity particularly against S. aureus.

After IV administration, daptomycin distributes into tissues but stays mostly in the bloodstream — it binds strongly to blood proteins (primarily albumin), with 90–93% of the drug bound at any given time. Its elimination half-life (the time for half the drug to leave the body) is roughly 8 hours in healthy adults, allowing once-daily dosing. Drug levels reach a stable steady state by the third daily dose. Daptomycin is primarily cleared by the kidneys, so patients with reduced kidney function need closer monitoring and possible dose adjustment. It is removed only slowly by dialysis.

Store original packages refrigerated between 2° and 8°C (36° and 46°F); avoid excessive heat. for the reconstituted and diluted solutions are described in another section of the prescribing information .