Ask the Expert: Monitoring Liver Function
QUESTION: Should Liver Function Be Monitored When Using Duloxetine to Treat Neuropathic Pain?
ANSWER: In June 2008, MedWatch—the US Food and Drug Administration Safety Information and Adverse Event Reporting Program— reported that the Center for Drug Evaluation and Research approved a labeling change to the prescribing information for duloxetine (Cymbalta).1 The change was made to the warnings and precautions section to warn of reports of hepatic dysfunction that were fatal in some patients who were treated with duloxetine. The prescribing information further states that duloxetine should be discontinued in patients who develop clinically significant liver dysfunction.2
There have been reports of elevated hepatic enzymes and hepatic injuries associated with duloxetine use in clinical trials, with a reported 1.1% of patients treated with duloxetine experiencing elevations in alanine aminotransferase (ALT) more than 3 times the upper limit of normal compared with 0.3% of patients treated with placebo.3 In fixed dose studies of duloxetine 60 mg and 120 mg, the higher duloxetine dose was associated with numerical increases in ALT.2 The prescribing information states to avoid alcohol use as this may worsen hepatic function.2
Practice guidelines from the American Psychiatric Association for the treatment of patients with major depressive disorder do not include recommendations on the monitoring of liver function tests (LFTs) in patients taking duloxetine or other serotonin-norepinephrine reuptake inhibitors. Close monitoring and initiation of lower starting doses may be necessary in those with liver dysfunction, but specific recommendations were not stated.4
Overall, there are no standard recommendations regarding the monitoring of liver function tests in patients receiving duloxetine. Clinical judgment is needed when assessing the appropriateness of testing. Not all patients may be candidates for frequent monitoring. However, obtaining baseline LFTs, especially in those with a history of alcohol or substance abuse or concomitant medications known to alter LFTs, should be considered. Since data show that the rise in liver function tests usually occurs within 2 months of starting duloxetine, monitoring after 2 to 3 months of starting or increasing the dose may be ideal in at-risk patients, based on past medical and social history.