Oritavancin Disease Interactions

Clostridioides difficile-associated diarrhea (CDAD), formerly pseudomembranous colitis, has been reported with almost all antibacterial drugs and may range from mild diarrhea to fatal colitis. The most common culprits include clindamycin and lincomycin. Antibacterial therapy alters the normal flora of the colon, leading to overgrowth of C difficile, whose toxins A and B contribute to CDAD development. Morbidity and mortality are increased with hypertoxin-producing strains of C difficile; these infections can be resistant to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea after antibacterial use. Since CDAD has been reported to occur more than 2 months after antibacterial use, careful medical history is necessary. Therapy with broad-spectrum antibacterials and other agents with significant antibacterial activity should be administered cautiously in patients with history of gastrointestinal disease, particularly colitis; pseudomembranous colitis (generally characterized by severe, persistent diarrhea and severe abdominal cramps, and sometimes associated with the passage of blood and mucus), if it occurs, may be more severe in these patients and may be associated with flares in underlying disease activity. Antibacterial drugs not directed against C difficile may need to be stopped if CDAD is suspected or confirmed. Appropriate fluid and electrolyte management, protein supplementation, antibacterial treatment of C difficile, and surgical evaluation should be started as clinically indicated.

Oritavancin has been shown to artificially prolong prothrombin time (PT) and international normalized ratio (INR) for up to 12 hours, making the monitoring of the anticoagulation effect of warfarin unreliable up to 12 hours after an oritavancin dose. Oritavancin has no effect on the coagulation system in vivo. Care should be taken when administering this agent to patients at risk for bleeding and they should be monitored for bleeding if concomitantly receiving warfarin. It is recommended to consider a non-phospholipid dependent coagulation test such as a Factor Xa (chromogenic) assay or an alternative anticoagulant not requiring aPTT monitoring for those patients requiring aPTT monitoring within 5 days of oritavancin dosing.

No dosage adjustment of oritavancin is needed in patients with mild or moderate hepatic impairment. Care should be taken when administering oritavancin to patients with severe hepatic impairment as the pharmacokinetics of this agent have not been studied.

No dosage adjustment of oritavancin is needed in patients with mild or moderate renal impairment. Care should be taken when administering oritavancin to patients with severe renal impairment as the pharmacokinetics of this agent have not been evaluated. Oritavancin is not removed from blood by hemodialysis.