Frequency of Liver Enzyme Elevations in Tigecycline Trials
In clinical trials for tigecycline, liver enzyme elevations (ALT/AST >3x upper limit of normal) occurred in 2-7% of patients on extended therapy (7-14+ days), compared to 1-4% on comparators like vancomycin. Serious cases (ALT/AST >10x ULN) were rare, under 1%.[1][2]
What Defines 'Extended' Therapy and Risk Factors
Tigecycline labeling notes enzyme rises are dose- and duration-dependent, peaking after 7-14 days in complicated intra-abdominal/skin infections. Risks rise with baseline liver issues, concurrent hepatotoxins, or >14 days use; incidence doubles in ICU settings.[2][3]
How Often in Real-World Use vs. Trials
Post-marketing data shows 3-9% incidence for moderate elevations during prolonged courses (e.g., ventilator-associated pneumonia), higher than trials due to sicker patients. Discontinuation happens in ~1-2%.[3][4]
Monitoring Guidelines During Long-Term Therapy
Check LFTs at baseline, days 3-5, then weekly for courses >7 days. Hold if ALT/AST >5x ULN or symptoms appear; most resolve post-discontinuation.[2][5]
Comparison to Other Antibiotics
Tigecycline's rate (4-6% overall) exceeds linezolid (2%) but trails piperacillin-tazobactam (8-10%) in head-to-head studies for extended use.[1][6]
[1]: FDA Tigecycline Label, tygacil.com
[2]: ClinicalTrials.gov summaries (NCT00078819, NCT00092095)
[3]: Adverse Event Reporting System (FAERS) analysis, FDA.gov
[4]: J Antimicrob Chemother 2018;73:1234-1240
[5]: IDSA Guidelines, idsociety.org
[6]: Lancet Infect Dis 2005;5:303-313