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Schizophrenia Drug Iloperidone (Fanapt) Demonstrates Long-Term Maintenance Effects

Eighty percent of patients remain relapse-free in pivotal trial

Results from the REPRIEVE trial –– a long-term maintenance study –– have demonstrated the ability of iloperidone (Fanapt, Vanda Pharmaceuticals) to prevent relapse or impending relapse in adult patients with schizophrenia. In the study, 79.6% of patients treated with iloperidone remained relapse-free compared with 36.6% of placebo-treated patients.

The findings were presented at the 2015 annual meeting of the American Society of Clinical Pharmacology in Miami Beach, Florida.

A supplemental new drug application (sNDA) for iloperidone is expected to be submitted to the FDA in the second half of 2015. The drug is currently indicated for the treatment of schizophrenia in adults.

The REPRIEVE trial was a randomized, double-blind, placebo-controlled study to evaluate the prevention of relapse in adult patients with schizophrenia receiving either flexible- dose iloperidone or placebo. In the stabilization phase, the subjects received open-label iloperidone titrated up to 12 mg/day (given as 6 mg twice daily) and were then stabilized for a further 14 to 24 weeks with flexible-dose iloperidone (8 to 24 mg/day). Subjects who remained clinically stable for at least 12 weeks entered the relapse prevention phase and were randomly assigned to continue on the same flexible-dose regimen of iloperidone or to switch from iloperidone to matched placebo in a double-blind fashion.

The subjects were followed for up to 26 weeks and were withdrawn upon showing signs of relapse or impending relapse. An unblinded interim analysis was conducted after 68 relapse or impending-relapse events were observed. The trial’s primary outcome was the time to relapse or impending relapse.

Of the 587 patients entering the open-label stabilization phase, 195 (33%) met the criteria for the double-blind relapse prevention phase, in which 99 subjects continued with iloperidone and 96 switched to placebo. The study was stopped early after 68 events confirmed the hypothesis that iloperidone was more effective than placebo in preventing relapse (P < 0.0001), with a Cox regression hazard ratio estimate of 4.7 favoring iloperidone. The percentage of iloperidone-treated patients remaining relapse-free at the end of the double-blind relapse prevention phase was of 79.6% compared with 36.6% for placebo-treated patients. The mean time to relapse was 139 days for iloperidone and 71 days for placebo.

The most common treatment-emergent adverse events (greater than or equal to 5%) related to iloperidone in the stabilization phase were dizziness, somnolence, and dry mouth.

Iloperidone is an atypical antipsychotic agent. In choosing among treatments, prescribers should first consider the ability of iloperidone to prolong the QT interval and the need to titrate iloperidone slowly to avoid orthostatic hypotension, which may lead to delayed effectiveness compared with that of some other drugs that do not require similar titration.

Sources: Vanda Pharmaceuticals; June 23, 2015; and Fanapt Prescribing Information; April 2014.


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