Police bring Ms. R, age 35, to the psychiatric ER after they find her asleep in a park. She is awake but drowsy, and states that she has a history of bipolar disorder. She claims that she had been stable on valproic acid (VPA), 1,500 mg/d, bupropion XL, 300 mg/d, quetiapine, 400 mg/d, and trazodone, 100 mg/d, until 2 weeks ago, when her best friend died and she stopped taking her medications all together. The previous evening, feeling “alone, hopeless, and sad,” she attempted suicide by ingesting a handful of VPA and clonazepam, obtained from a friend, and 2 liters of vodka. She complains of nausea, vomiting, and abdominal pain. Elevated laboratory chemistries included aspartate aminotransferase (AST), 220 U/L; alanine aminotransferase (ALT), 182 U/L; alkaline phosphatase (AP), 75 U/L; γ-glutamyltransferase (GGT), 104 U/L; total bilirubin, 1.4 mg/dL; and an elevated VPA serum concentration of 152 μg/mL.
Drug-induced hepatotoxicity accounts for approximately 50% of acute liver failure cases, and almost 10% of liver transplants in some facilities.1 The incidence of drug-induced hepatotoxicity is between 0.001% and 0.1% in patients on standard medication doses.2 Drug-induced hepatotoxicity is characterized by:
• abnormalities in laboratory parameters (hepatocellular, cholestatic, or mixed)
• mechanisms of toxicity (direct, immune-mediated, idiosyncratic, mitochondrial toxicity)
• liver biopsy histology (steatosis, sinusoidal obstruction syndrome).3
Liver function test results of hepatocellular injury are characterized by ALT elevation and minimal AP elevation, whereas cholestatic injury manifests as high AP. Table 13 categorizes psychotropics based on type of liver injury and how each injury manifest in liver function tests. Delayed idiosyncratic reactions occur after taking the drug, whereas direct toxicities are dose-dependent and more predictable. By definition, a clinically significant hepatotoxicity is associated with an ALT >3 times the upper limit of normal.3
VPA-induced liver injury occurs in approximately 1 in 37,000 persons taking the drug.4 Patients at an increased risk of VPA-induced liver injury include:
• children
• patients with mitochondrial enzyme deficiencies
• Reye’s syndrome
• Friedreich’s ataxia
• polypharmacy patients
• patients with a sibling who has experienced VPA toxicity.4
Benign enzyme elevations occur in approximately 20% of patients taking VPA.5 In Ms. R’s case, concomitant VPA, clonazepam, and alcohol may have led to elevations in ALT, AST, and GGT. Her nausea, vomiting, and abdominal pain are consistent with hepatic dysfunction.
Carnitine is effective in increasing survival of patients with VPA-induced hepatotoxicity.4 Because Ms. R is symptomatic, discontinuing VPA and administering IV L-carnitine is warranted.5 L-carnitine can be initiated at 100 mg/kg as an IV bolus, followed by 50 mg/kg as an IV infusion every 8 hours, with a maximum dosage of 3,000 mg.6 Patients may require several days of therapy based on symptoms. L-carnitine should be continued until a patient shows clinical improvement, such as decreases in ALT and AST.
Ms. R experienced a VPA-induced hepatotoxic reaction. However, continuous monitoring is appropriate for all patients who are prescribed any potentially hepatotoxic psychotropic, especially after hepatic injuries resolve. This includes mood stabilizers, antipsychotics, benzodiazepines, selective serotonin reuptake inhibitors (SSRIs), and serotonin-norepinephrine reuptake inhibitors, especially when given concomitantly with other hepatotoxic agents.
Table 2 lists dosing recommendations for commonly used psychotropics in patients with hepatic impairment. Among mood stabilizers, carbamazepine and VPA are associated with the highest incidence of hepatotoxicity.2 A follow-up study of more than 1,000,000 VPA prescriptions found 29 cases of fatal hepatotoxicity in a 7-year period.7 Although there are case reports of hepatotoxicity with oxcarbazepine, it may have a better liver safety profile than carbamazepine.2 Hepatotoxicity with lamotrigine is rare, although fatal cases have been reported.5
When initiating an antipsychotic, a temporary, benign increase in liver enzymes can be expected, but typically discontinuation is unnecessary.2 Phenothiazines in particular can cause increases in liver enzymes in 20% of patients.2 Hepatotoxicity with benzodiazepines is infrequent, with a few cases of cholestatic injury reported with diazepam, chlordiazepoxide, and flurazepam.2
SSRIs are relatively safe; incidents of hepatic injury are rare. Among SSRIs, paroxetine is most frequently associated with hepatotoxicity. Abnormal liver function tests have been observed with fluoxetine (0.5% of long-term recipients) and other SSRIs.1,2,4
Among antidepressants with dual serotonergic action, nefazodone carries a black-box warning for hepatotoxicity and is used rarely, whereas trazodone is not regarded as hepatotoxic.2 Antidepressants with dual norepinephrine and serotonin reuptake inhibitor properties carry a higher risk of liver injury, especially duloxetine. Hepatocellular, cholestatic, and mixed types of hepatotoxicity are associated with duloxetine-induced hepatotoxicity.2
Monitoring recommendations
Before prescribing potentially hepatotoxic medications, order baseline liver function tests. During therapy, periodic liver function monitoring is recommended. Elevated transaminase concentrations (>3 × the upper limit of normal), bilirubin (>2 × the upper limit of normal), and prolonged prothrombin times are indicators of hepatic injury.2 Caution should be taken to prevent polypharmacy with multiple hepatotoxic medications and over-the-counter use of hepatotoxic drugs and supplements.
When choosing a psychotropic, take into account patient-specific factors, such as underlying liver disease and alcohol consumption. Patients on potentially hepatotoxic medications should be counseled to recognize and report symptoms of liver dysfunction, including nausea, vomiting, jaundice, and lower-extremity edema.2 If liver injury occurs, modify therapy with the potential offending agent and check liver function periodically.