What's the increase in liver enzymes with prolonged tigecycline use?

Prolonged tigecycline use can cause liver test abnormalities. In clinical trials, elevations in liver enzymes (ALT/AST) occurred in a minority of patients and were usually mild. Roughly:

- ALT/AST elevations: seen in about 2–6% of patients
- Most elevations were mild (often within 1–3× ULN)
- Severe elevations (greater than 5× ULN) or clinically significant liver injury were rare (a small fraction of patients)

Bilirubin elevations have been reported less commonly.

Because the risk exists, liver function tests (ALT, AST, bilirubin) are typically checked at baseline and periodically during longer courses (e.g., if therapy extends beyond 7–14 days, or sooner if symptoms suggest liver injury). If there is a significant rise or signs of liver injury (jaundice, dark urine, right upper quadrant pain, malaise), tigecycline should be stopped and liver evaluation pursued.

Notes:
- The drug labeling cautions about hepatic safety and states that safety/efficacy in severe hepatic impairment isn’t established.
- Patients with preexisting liver disease or on other hepatotoxic drugs may have higher risk.

If you want, I can pull the exact figures from the latest labeling or a specific trial.