Tigecycline's Primary Liver Enzyme Effects
Tigecycline, a glycylcycline antibiotic, primarily affects alanine aminotransferase (ALT) and aspartate aminotransferase (AST). These elevations occur in 10-20% of patients, typically mild to moderate and reversible after treatment ends.[1]
How Common Are These Elevations?
In clinical trials, ALT increases (>3x upper limit of normal) affected up to 15% of patients, AST up to 12%, with higher rates in hepatic impairment. Alkaline phosphatase (ALP) and total bilirubin rise less often, in under 5%.[1][2]
Why Does Tigecycline Impact ALT and AST?
It disrupts mitochondrial protein synthesis in hepatocytes, leading to transaminase leakage. Risk rises with prolonged use (>14 days) or IV dosing >100 mg/day. No direct cholestatic effect on gamma-glutamyl transferase (GGT).[2][3]
Monitoring and Management Guidelines
Check baseline liver function tests (LFTs) before starting, then weekly. Hold tigecycline if ALT/AST >5x ULN with symptoms or >10x ULN alone. Most resolve within 1-4 weeks post-discontinuation.[3]
Comparison to Other Antibiotics
Unlike tetracyclines (minimal LFT impact), tigecycline shows 2-3x higher transaminase elevations than comparators like vancomycin or levofloxacin. Linezolid affects similar enzymes but at lower rates.[2]
[1]: Tigecycline Prescribing Information (Pfizer)
[2]: FDA Adverse Event Reporting System (FAERS) Summary
[3]: Hepatic Safety Review, Clinical Infectious Diseases (2008)