Tigecycline is a glycylcycline derivative that overcomes tetracycline resistance. It achieves this by:

• A Being bactericidal, unlike bacteriostatic tetracyclines
• B Binding to a slightly different 16S rRNA site on the 30S subunit compared to tetracyclines
• C It is administered intravenously, bypassing the gut where tetracyclinases reside
• D Its bulky 9-glycylamido substituent sterically inhibits tetracycline efflux pumps (TetA–TetE) and overcomes ribosomal protection proteins (TetM, TetO) ✓

Explanation

Tigecycline has a 9-t-butylglycylamido group at position 9 of the tetracycline scaffold; this large substituent sterically blocks the efflux pump transporters (Tet efflux proteins) from recognizing and expelling the drug, and also prevents ribosomal protection proteins (Tet-M, Tet-O) from displacing the drug from the 30S ribosome. It still binds the same 30S 16S rRNA site as tetracyclines. Tigecycline remains bacteriostatic and has markedly lower serum levels due to large volume of distribution.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.