Following oral administration of iloperidone (iloperidone and milsaperidone rapidly interconvert in vivo), the plasma exposure of milsaperidone increased approximately proportionally over the therapeutic dosage range and plasma exposure of iloperidone increased slightly more than dose proportional. Steady-state concentrations of milsaperidone are attained within 3 to 4 days of dosing. Accumulation of iloperidone is at least 2-fold with twice daily dosing regimen after administration of oral iloperidone tablets.
After administration of oral iloperidone tablets (iloperidone and milsaperidone rapidly interconvert in vivo) in CYP2D6 normal metabolizers, the major metabolite P95, milsaperidone, and iloperidone accounted for approximately 48%, 20% and 9% of the total plasma exposure, respectively. After administration of oral iloperidone tablets in CYP2D6 poor metabolizers, the major metabolite P95, milsaperidone, and iloperidone accounted for 23%, 34%, and 16% of the total exposure, respectively.
Absorption
Following oral administration of BYSANTI or oral iloperidone tablets, no clinically significant differences in the pharmacokinetics of milsaperidone and its metabolites, iloperidone and P95 were observed with the two treatments.Following oral administration of BYSANTI, the time to peak plasma concentrations (Tmax) occurred within 4 hours for milsaperidone, 2 hours for iloperidone, and 6 hours for P95.
Effect of Food: Following administration of BYSANTI with high-fat meal (approximately 1000 calories, 50% fat), no clinically significant differences in the pharmacokinetics of milsaperidone and its metabolites were observed compared to the fasted state.
Distribution
Milsaperidone and iloperidone have an apparent volume of distribution of 1715-2343 L and 1340-2800 L, respectively. At therapeutic concentrations, the unbound fraction in plasma is approximately 8% for milsaperidone, 3% for iloperidone and 8% for P95.
Elimination
In CYP2D6 normal metabolizers, the observed mean elimination half-lives were 26 hours for milsaperidone, 18 hours for iloperidone, and 23 hours for P95. In CYP2D6 poor metabolizers, the mean elimination half-lives were 37 hours for milsaperidone, 33 hours for iloperidone, and 31 hours for P95.
Milsaperidone and iloperidone have an apparent clearance (clearance/bioavailability) of 32 to 69 L/h and 47 to 102 L/h, respectively.
Metabolism: Milsaperidone undergoes oxidation to form iloperidone and iloperidone undergoes a stereospecific carbonyl reduction to form milsaperidone. Elimination of milsaperidone and iloperidone is mainly through hepatic metabolism. Iloperidone is metabolized primarily by 3 biotransformation pathways: carbonyl reduction, hydroxylation (mediated by CYP2D6) and O-demethylation (mediated by CYP3A4).
Excretion: Studies of iloperidone showed the majority of the radioactive materials were recovered in the urine. The mean recovery was 58% in CYP2D6 normal metabolizers and 45% in CYP2D6 poor metabolizers, with feces accounting for 20% in CYP2D6 normal metabolizers and 22% in CYP2D6 poor metabolizers of the administered radioactivity.
Specific Populations
No pharmacokinetics (PK) studies with BYSANTI have been performed in specific populations. The PK of milsaperidone is based on PK studies of iloperidone.
Patients with Renal Impairment: Studies of iloperidone show patients with severe renal impairment (creatinine clearance <30 mL/minute) had minimal effect on Cmax of iloperidone, milsaperidone and P95 compared to those with normal kidney function; AUCinf was increased by 24% for iloperidone, decreased by 6% for milsaperidone and increased by 52% for P95.
Patients with Hepatic Impairment: In patients with moderate hepatic impairment (HI), a 2-fold higher free plasma exposure for milsaperidone was observed and these exposures were variable (these changes are clinically significant), whereas there was a 19% increase in iloperidone exposure and a 5% decrease in P95 exposure. Studies in patients with severe HI have not been conducted. In studies of iloperidone, there were no significant differences in the pharmacokinetics of iloperidone, milsaperidone or P95 (total or unbound) in adult patients with mild HI compared to adults with normal hepatic function. [see Dosage and Administration (2.3), Use in Specific Populations (8.6)]
Drug Interactions Studies
Clinical studies:The effects of fluoxetine and ketoconazole on the exposures of iloperidone, milsaperidone, and P95 are summarized in Figure 1.
Figure 1: Effect of CYP3A4 and CYP2D6 Inhibitors on the Pharmacokinetics of Milsaperidone, Iloperidone, and P95
Figure 1 (Milsaperidone 03)
Results are based on single 3mg doses of iloperidone; top: effect of concomitant administration of a strong CYP2D6 inhibitor (fluoxetine) and bottom: concomitant administration of a strong CYP3A4 inhibitor (ketoconazole). Data are GMRs and 90% CIs. AUC∞: area under the plasma concentration-time curve from time zero extrapolated to infinity; Cmax: maximum plasma concentration, CI: confidence interval; GMRs: geometric mean ratios.
Strong CYP2D6 Inhibitors: Concomitant administration of fluoxetine (a strong CYP2D6 inhibitor) (20 mg twice daily for 21 days) with a single 3 mg dose of iloperidone in CYP2D6 normal metabolizers, increased the AUC of iloperidone and milsaperidone by approximately 2- to 3-fold and decreased the AUC of P95 by one-half [see Drug Interactions (7.1)]. Concomitant administration of a single 3 mg iloperidone dose had no effect on the steady-state pharmacokinetics of fluoxetine.
Concomitant administration of paroxetine (a strong CYP2D6 inhibitor) (20 mg/day for 5-8 days) with multiple doses of iloperidone (8 or 12 mg twice daily) to patients with schizophrenia resulted in increased mean steady-state peak concentrations of iloperidone and milsaperidone, by about 1.6-fold, and decreased mean steady-state peak concentrations of P95 by one-half [see Drug Interactions (7.1)].
Strong CYP3A4 Inhibitors: Concomitant administration of ketoconazole (a strong CY3A4 inhibitor) (200 mg twice daily for 4 days) with a 3 mg single dose of iloperidone, increased the iloperidone AUC by 57%, the milsaperidone AUC by 55% and the P95 AUC by 35%. Concomitant use of BYSANTI or iloperidone have not been studied with CYP3A4 moderate inhibitors (e.g., erythromycin, grapefruit juice).
Strong CYP2D6 and CYP3A4 Inhibitors: Concomitant administration of paroxetine (20 mg once daily for 10 days) a strong CYP2D6 inhibitor, and ketoconazole (200 mg twice daily), a strong CYP3A4 inhibitor with multiple doses of iloperidone (8 or 12 mg twice daily) in patients with schizophrenia resulted in a 1.4-fold increase in steady-state peak concentrations of both iloperidone and milsaperidone, and a 1.4-fold decrease in steady-state peak concentrations of P95 when compared to paroxetine alone [see Drug Interactions (7.1)].
Sensitive CYP2D6 Substrates: Concomitant administration of a single 3 mg iloperidone dose with a single 80 mg dextromethorphan dose (a sensitive CYP2D6 substrate) resulted in a 17% increase in AUC and a 26% increase in Cmax for dextromethorphan. Thus, an interaction between iloperidone and other CYP2D6 substrates is unlikely.
Sensitive CYP3A4 substrates: Concomitant administration of midazolam (a sensitive 3A4 substrate) with steady-state iloperidone in patients with schizophrenia showed a less than 50% increase in midazolam AUC and no effect on midazolam Cmax. Thus, an interaction between iloperidone and other CYP3A4 substrates is unlikely.
In Vitro Drug Interaction Studies
Cytochrome P450 (CYP450) Enzymes: Iloperidone is an inhibitor of CYP isozymes 3A4, 3A5 and 2D6. Iloperidone does not inhibit CYP isozymes 1A1, 1A2, 2A6, 2B6, 2C8, 2C9, or 2E1. Iloperidone also does not induce CYP isozymes 1A2, 2C8, 2C9, 2C19, 3A4 and 3A5. Iloperidone is not a substrate of CYP isozymes 1A1, 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, or 2E1 enzymes. This suggests that an interaction of iloperidone with inhibitors or inducers of these enzymes, or other factors, like smoking, is unlikely.
Transporter Systems: Iloperidone and milsaperidone are not substrates of P-gp and iloperidone is a weak P-gp inhibitor.