Does Sivextro Treat MRSA?
Yes, Sivextro (tedizolid phosphate) treats acute bacterial skin and skin structure infections (ABSSSI) caused by susceptible strains of methicillin-resistant Staphylococcus aureus (MRSA). The FDA approved it in 2014 specifically for this indication, including MRSA, based on clinical trials showing non-inferiority to linezolid in eradicating MRSA from ABSSSI lesions.[1][2]
How Does Sivextro Work Against MRSA?
Sivextro is a protein synthesis inhibitor in the oxazolidinone class. It binds to the bacterial ribosome's P-site, blocking MRSA's ability to grow and replicate. Its once-daily IV or oral dosing for 6 days targets Gram-positive bacteria like MRSA, with strong activity against strains resistant to other antibiotics.[1][3]
When Is Sivextro Used for MRSA?
Physicians prescribe it for complicated ABSSSI, such as cellulitis, major abscesses, or wound infections involving MRSA. It's not approved for pneumonia, bacteremia, or osteomyelitis, though off-label use occurs in some resistant cases. Guidelines from IDSA recommend it as an alternative to vancomycin or linezolid for skin infections when oral therapy is needed.[2][4]
How Does Sivextro Compare to Vancomycin or Linezolid for MRSA?
| Drug | Dosing | MRSA Coverage | Key Differences |
|------|--------|---------------|-----------------|
| Sivextro | 200 mg once daily, 6 days (IV/oral) | Excellent; MIC ≤0.5 mcg/mL for most strains | Shorter course, fewer GI side effects, no serotonin syndrome risk |
| Linezolid (Zyvox) | 600 mg twice daily, 10-14 days (IV/oral) | Excellent | Longer treatment; higher myelosuppression risk with extended use |
| Vancomycin | Weight-based IV, 7-14 days | Standard for MRSA | IV only; requires monitoring for kidney toxicity |
Sivextro often edges out linezolid in patient convenience and tolerability for short-course ABSSSI.[3][5]
What Are Common Side Effects with MRSA Treatment?
Nausea (8%), headache (6%), and diarrhea (4%) top the list. It's better tolerated than linezolid, with minimal risk of thrombocytopenia even after 6 days. Rare cases of Clostridium difficile infection or peripheral neuropathy occur with prolonged use.[1][2]
Availability, Cost, and Patent Status
Sivextro remains under patent protection until at least 2036 in the US, with no generics approved yet.[6] A 6-day course costs $2,500-$3,000 without insurance, though patient assistance programs exist. Merck markets it.
Limitations and Resistance Concerns
Not all MRSA strains are susceptible—check local antibiograms. It lacks coverage for Gram-negatives, so polymicrobial infections need combo therapy. Emerging tedizolid resistance is rare but monitored.[4][5]
Sources:
[1]: Sivextro Prescribing Information (FDA)
[2]: IDSA Skin and Soft Tissue Guidelines (2014)
[3]: Clinical Trials Data (NEJM, 2014)
[4]: CDC MRSA Treatment Guidelines
[5]: UpToDate: Tedizolid Overview
[6]: DrugPatentWatch: Sivextro Patents