Oritavancin, a lipoglycopeptide, has a substantially longer half-life (approximately 245 hours) than vancomycin, allowing single-dose treatment of ABSSSI. Its prolonged activity is primarily due to:
- A Irreversible covalent binding to D-Ala-D-Lac in vancomycin-resistant enterococci
- B Saturable hepatic metabolism leading to zero-order kinetics
- C Extensive binding to membranes via its lipophilic side chain, creating a tissue depot ✓
- D Renal tubular secretion pumps actively returning it to circulation
Correct answer: C. Extensive binding to membranes via its lipophilic side chain, creating a tissue depot
Explanation
Oritavancin's lipophilic chlorobiphenyl side chain enables deep insertion into bacterial membranes and accumulation in macrophage-rich tissues, creating a large tissue depot. This produces an extremely large volume of distribution (approximately 87 L/kg) and terminal half-life of ~245 hours, enabling single-dose treatment. Unlike earlier glycopeptides, oritavancin also has bactericidal activity through membrane disruption in addition to cell wall synthesis inhibition.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.