Absorption
The absolute oral bioavailability of FARYDAK is approximately 21%. Peak concentrations of panobinostat are observed within 2 hours (Tmax) of oral administration in patients with advanced cancer. FARYDAK exhibits an approximate dose proportional increase in both Cmax and AUC over the dosing range.
Plasma panobinostat Cmax and AUC0–48 were approximately 44% and 16% lower compared to fasting conditions, respectively, following ingestion of an oral FARYDAK dose 30 minutes after a high-fat meal by 36 patients with advanced cancer. The median Tmax was also delayed by 2.5 hours in these patients.
The aqueous solubility of panobinostat is pH dependent, with higher pH resulting in lower solubility [see Description (11)]. Coadministration of FARYDAK with drugs that elevate the gastric pH was not evaluated in vitro or in a clinical trial; however, altered panobinostat absorption was not observed in simulations using physiologically-based pharmacokinetic (PBPK) models.
Distribution
Panobinostat is approximately 90% bound to human plasma proteins in vitro and is independent of concentration. Panobinostat is a P-gp substrate.
Metabolism
Panobinostat is extensively metabolized. Pertinent metabolic pathways involved in the biotransformation of panobinostat are reduction, hydrolysis, oxidation, and glucuronidation processes. The fraction metabolized through CYP3A accounts for approximately 40% of the total hepatic panobinostat elimination. In vitro, additional contributions from the CYP2D6 and CYP2C19 pathways are minor. In vitro, UGT1A1, UGT1A3, UGT1A7, UGT1A8, UGT1A9, and UGT2B4 contribute to the glucuronidation of panobinostat.
Elimination
Twenty-nine percent to 51% of administered radioactivity is excreted in urine and 44% to 77% in the feces after a single oral dose of [14C] panobinostat in 4 patients with advanced cancer. Unchanged panobinostat accounted for <2.5% of the dose in urine and <3.5% of the dose in feces with the remainder consisting of metabolites.
An oral clearance (CL/F) and terminal elimination half-life (t1/2) of approximately 160 L/hr and 37 hours, respectively, was estimated using a population based pharmacokinetic (pop-PK) model in patients with advanced cancer. An inter-subject variability 65% on the clearance estimate was also reported. Up to 2-fold accumulation was observed with chronic oral dosing in patients with advanced cancer.
Specific Populations
Population pharmacokinetic (PK) analyses of FARYDAK indicated that body surface area, gender, age, and race do not have a clinically meaningful influence on clearance.
Hepatic Impairment: The effect of hepatic impairment on the pharmacokinetics of panobinostat was evaluated in a phase 1 study in 24 patients with advanced cancer with varying degrees of hepatic impairment. In patients with NCI-CTEP class mild (i.e., Group B) and moderate (i.e., Group C) hepatic impairment, AUC0-inf increased 43% and 105% compared to the group with normal hepatic function, respectively. The relative change in Cmax followed a similar pattern. The effect of severe hepatic impairment was indeterminate in this study due to the small sample size (n=1). A dose modification is recommended for patients with mild and moderate hepatic impairment [see Use in Specific Populations (8.6)].
Renal Impairment: The effect of renal impairment on the pharmacokinetics of panobinostat was assessed in a phase 1 trial of 37 patients with advanced cancer and varying degrees of renal impairment. Panobinostat AUC0–inf in the mild, moderate and severe renal impairment groups were 64%, 99% and 59%, of the normal group, respectively. The relative change in Cmax followed a similar pattern [see Use in Specific Populations (8.7)].
Drug Interactions:
Strong CYP3A Inhibitors: Coadministration of a single 20 mg FARYDAK dose with ketoconazole (200 mg twice daily for 14 days) increased the Cmax and AUC0–48 of panobinostat by 62% and 73% respectively, compared to when FARYDAK was given alone in 14 patients with advanced cancer. Tmax was unchanged. A modified starting dose is recommended [see Dose and Administration (2.4), Drug Interactions (7.1)].
Strong CYP3A Inducers: The human oxidative metabolism of panobinostat via the cytochrome P450 system primarily involves CYP3A isozymes. Simulations using PBPK models, predicted an approximately 70% decrease in the systemic exposure of panobinostat in the presence of strong inducers of CYP3A. Avoid coadministration of FARYDAK with strong CYP3A inducers [see Drug Interactions (7.2)].
CYP2D6 Substrates: Coadministration of a single 60 mg dextromethorphan (DM) dose with FARYDAK (20 mg once per day, on Days 3, 5, and 8) increased the Cmax and AUC0–∞ of DM by 20% to 200% and 20% to 130% (interquartile ranges), respectively, compared to when DM was given alone in 14 patients with advanced cancer. These DM exposures were extremely variable (CV% >150%). Avoid coadministration of FARYDAK with sensitive CYP2D6 substrates or CYP2D6 substrates that have a narrow therapeutic index [see Drug Interactions (7.3)].
CYP3A Substrates: Simulations using PBPK models predict that an exposure increase of less than 10% for the sensitive CYP3A substrate midazolam is likely following coadministration with panobinostat. The clinical implications of this finding are not known.
In vitro studies with CYP or UDPglucuronosyltransferase (UGT) substrates:
Panobinostat inhibits CYP2D6, CYP2C19 and CYP3A4 (time-dependent), but does not inhibit CYP1A2, CYP2C8, CYP2C9, and CYP2E. Panobinostat does not induce CYP1A1/2, CYP2B6, CYP2C8/9/19, CYP3A and UGT1A1.
In vitro studies with drug transporter system substrates:
Panobinostat inhibits OAT3, OCT1, OCT2, OATP1B1 and OATP1B3, but does not inhibit P-gp and breast cancer resistant protein (BCRP), or OAT1.
Panobinostat does not induce P-gp and multidrug resistance protein 2 (MRP2) transporters.