Home›The Library›Oritavancin
Oritavancin
Oritavancin (Orbactiv) is a real, FDA-approved lipoglycopeptide antibiotic, similarly built for single-dose treatment as dalbavancin — with a triple mechanism that gives it activity against vancomycin-resistant enterococci, and a genuinely practical lab-interference quirk: it can falsely prolong clotting-test results for up to two days after dosing.
On this page
In brief
Should you care? Relevant only in hospital-level skin-infection treatment, but genuinely useful to know if you or a family member is on it and also needs bloodwork.The short version
- A triple mechanism — cell-wall synthesis inhibition at two separate points, plus membrane disruption — gives it real activity against vancomycin-resistant enterococci (VRE).
- Approved August 2014 as a single 1,200mg IV dose covering an entire treatment course.
- Falsely prolongs common clotting lab tests for up to 48 hours — a real practical issue, not a true bleeding risk, that clinicians need to know about.
A triple mechanism, including VRE activity
Oritavancin is a semi-synthetic lipoglycopeptide with three distinct mechanisms: it inhibits transglycosylation (blocking peptidoglycan precursor assembly), inhibits transpeptidation (blocking the cross-linking bridges), and its hydrophobic side chain drives concentration-dependent membrane depolarization. That third mechanism is specifically credited with giving oritavancin real activity against vancomycin-resistant enterococci (VRE) — a genuine differentiator from dalbavancin, which shares oritavancin's long-half-life single-dose convenience but not this VRE activity.
The approval and pivotal trials
The FDA approved oritavancin (as Orbactiv) on 6 August 2014 for acute bacterial skin and skin-structure infections, as a single 1,200mg IV dose. The pivotal SOLO trial program (Corey et al., N Engl J Med 2014, PMID 24897083) compared single-dose oritavancin to 7-10 days of twice-daily vancomycin, finding oritavancin non-inferior.
A real lab-interference quirk
Oritavancin binds phospholipid reagents used in common coagulation lab tests, artificially prolonging aPTT for up to roughly 48 hours and PT/INR for up to roughly 24 hours after dosing — not a true effect on the patient's actual clotting ability, but a genuine lab-assay artifact with real practical consequences: unfractionated heparin is contraindicated for 48 hours after an oritavancin dose specifically because aPTT can no longer be reliably monitored during that window. The label separately advises against use for osteomyelitis, a caution that traces to a small imbalance of osteomyelitis diagnoses in the original SOLO trial safety data — though FDA reviewers attributed most of those cases to pre-existing, undiagnosed infection at enrollment rather than a drug effect, and more recent real-world use in osteomyelitis has reported considerably higher success rates than that original signal might suggest.
Current status
Still marketed, with ownership changing hands as recently as 2025 (CorMedix completed its acquisition of Melinta Therapeutics, Orbactiv's prior owner, in August 2025). Hospital/infusion-clinic use, no wellness or grey-market presence.
References
- Corey GR, Kabler H, Mehra P, et al. (SOLO I Investigators), "Single-Dose Oritavancin in the Treatment of Acute Bacterial Skin Infections," N Engl J Med 2014;370(23):2180-2190, PMID 24897083, DOI: 10.1056/NEJMoa1310422.
- FDA approval history for Orbactiv (oritavancin), 6 August 2014. CorMedix acquisition of Melinta Therapeutics (Orbactiv's prior owner), August 2025.