EPIDIOLEX can cause dose-related elevations of liver transaminases (alanine aminotransferase [ALT] and/or aspartate aminotransferase [AST]). In controlled studies for LGS and DS (10 and 20 mg/kg/day dosages) and TSC (25 mg/kg/day), the incidence of ALT elevations above 3 times the upper limit of normal (ULN) was 13% (10 and 20 mg/kg/day dosages) and 12% (25 mg/kg/day dosage) in EPIDIOLEX-treated patients compared with 1% in patients on placebo. Less than 1% of EPIDIOLEX-treated patients had ALT or AST levels greater than 20 times the ULN. There were cases of transaminase elevations associated with hospitalization in patients taking EPIDIOLEX. In clinical trials, serum transaminase elevations typically occurred in the first two months of treatment initiation; however, there were some cases observed up to 18 months after initiation of treatment, particularly in patients taking concomitant valproate. Resolution of transaminase elevations occurred with discontinuation of EPIDIOLEX or reduction of EPIDIOLEX and/or concomitant valproate in about two-thirds of the cases. In about one-third of the cases, transaminase elevations resolved during continued treatment with EPIDIOLEX, without dose reduction. 

In the postmarketing setting, cases of cholestatic or mixed patterns of liver injury (i.e., based on calculated ratio of [ALT/ULN]/[ALP/ULN] less than 2 and between 2-5, respectively) were reported in patients treated with EPIDIOLEX.

Risk Factors for Transaminase Elevation

Concomitant Valproate and Clobazam

The majority of ALT elevations in the controlled studies occurred in patients taking concomitant valproate [see Drug Interactions (7.3)]. Concomitant use of clobazam also increased the incidence of transaminase elevations, although to a lesser extent than valproate [see Drug Interactions (7.2)]. In EPIDIOLEX-treated patients with LGS or DS (10 and 20 mg/kg/day dosages), the incidence of ALT elevations greater than 3 times the ULN was 30% in patients taking both concomitant valproate and clobazam, 21% in patients taking concomitant valproate (without clobazam), 4% in patients taking concomitant clobazam (without valproate), and 3% in patients taking neither drug. In EPIDIOLEX-treated patients with TSC (25 mg/kg/day), the incidence of ALT elevations greater than 3 times the ULN was 20% in patients taking both concomitant valproate and clobazam, 25% in patients taking concomitant valproate (without clobazam), 0% in patients taking concomitant clobazam (without valproate), and 6% in patients taking neither drug. 

Consider discontinuation or dose adjustment of valproate or clobazam if liver enzyme elevations occur.

In the postmarketing setting, cases of elevated ammonia levels were reported in some EPIDIOLEX-treated patients who also had transaminase elevations; where data were available, most cases reported concomitant use of valproate, clobazam, or both. Consider discontinuation or dose adjustment of valproate or clobazam if ammonia level elevations occur.

Dose

Transaminase elevations are generally dose-related. In patients with DS or LGS (10 and 20 mg/kg/day) or TSC (25 mg/kg/day), ALT elevations greater than 3 times the ULN were reported in 17% and 12% of patients taking EPIDIOLEX 20 or 25 mg/kg/day, respectively, compared with 1% in patients taking EPIDIOLEX 10 mg/kg/day. The risk of ALT elevations was higher (25%) in patients with TSC receiving a dosage above the recommended maintenance dosage of 25 mg/kg/day in Study 4.

Baseline Transaminase Elevations

Patients with baseline transaminase levels above the ULN had higher rates of transaminase elevations when taking EPIDIOLEX. In the DS and LGS controlled trials (Studies 1, 2, and 3) in patients taking EPIDIOLEX 20 mg/kg/day, the frequency of treatment-emergent ALT elevations greater than 3 times the ULN was 30% when ALT was above the ULN at baseline, compared to 12% when ALT was within the normal range at baseline. No patients taking EPIDIOLEX 10 mg/kg/day experienced ALT elevations greater than 3 times the ULN when ALT was above the ULN at baseline, compared with 2% of patients in whom ALT was within the normal range at baseline. In the TSC controlled trial (Study 4) in patients taking EPIDIOLEX 25 mg/kg/day, the frequency of treatment-emergent ALT elevations greater than 3 and 5 times the ULN were both 11% when ALT was above the ULN at baseline, compared to 12% and 6%, respectively, when ALT was within the normal range at baseline.

Monitoring

In general, transaminase elevations of greater than 3 times the ULN in the presence of elevated bilirubin without an alternative explanation are an important predictor of severe liver injury. Early identification of elevated liver enzymes may decrease the risk of a serious outcome. Patients with elevated baseline transaminase levels above 3 times the ULN, accompanied by elevations in bilirubin above 2 times the ULN, should be evaluated prior to initiation of EPIDIOLEX treatment.

Prior to starting treatment with EPIDIOLEX, obtain serum transaminases (ALT and AST) and total bilirubin levels. Serum transaminases and total bilirubin levels should be obtained at 1 month, 3 months, and 6 months after initiation of treatment with EPIDIOLEX, and periodically thereafter or as clinically indicated. Serum transaminases and total bilirubin levels should also be obtained within 1 month following changes in EPIDIOLEX dosage and addition of or changes in medications that are known to impact the liver. Consider more frequent monitoring of serum transaminases and bilirubin in patients who are taking valproate or who have elevated liver enzymes at baseline.

If a patient develops clinical signs or symptoms suggestive of hepatic dysfunction (e.g., unexplained nausea, vomiting, right upper quadrant abdominal pain, fatigue, anorexia, or jaundice and/or dark urine), promptly measure serum transaminases and total bilirubin and interrupt or discontinue treatment with EPIDIOLEX, as appropriate. Discontinue EPIDIOLEX in any patients with elevations of transaminase levels greater than 3 times the ULN and bilirubin levels greater than 2 times the ULN. Patients with sustained transaminase elevations of greater than 5 times the ULN should also have treatment discontinued. Patients with prolonged elevations of serum transaminases should be evaluated for other possible causes. Consider dosage adjustment of any coadministered medication that is known to affect the liver (e.g., valproate and clobazam).