Leslie Citrome, MD, MPH Clinical Professor Department of Psychiatry and Behavioral Sciences New York Medical College Valhalla, New York
Disclosure In the past 12 months, Dr. Citrome has served as a consultant to Acadia, Alkermes, Allergan, Intra-Cellular Therapeutics, Janssen, Lundbeck, Merck, Neurocrine, Noven, Otsuka, Pfizer, Shire, Sunovion, Takeda, Teva, and Vanda; and a speaker for Acadia, Alkermes, Allergan, Janssen, Lundbeck, Merck, Neurocrine, Otsuka, Pfizer, Shire, Sunovion, Takeda, Teva, and Vanda.
From the 2 positive pivotal short-term acute MDD trials for aripiprazole,16,17 using the definition of response as a ≥50% decrease in the Montgomery-Åsberg Depression Rating Scale (MADRS) total score, and pooling the data (aripiprazole flexibly dosed 2 to 20 mg/d, with a median dose of 10 mg/d), response rates were 33% for aripiprazole vs 20% for placebo, resulting in a NNT of 8 (95% CI 6 to 17). After including a third trial not described in product labeling,18 the NNT became a more robust 7 (95% CI 5 to 11).1
The most commonly encountered adverse events (incidence ≥5% and at least twice the rate of placebo) in the pivotal trials were akathisia (schizophrenia); akathisia, sedation, restlessness, tremor, and extrapyramidal disorder (bipolar mania, monotherapy); akathisia, insomnia, and extrapyramidal disorder (bipolar mania, adjunctive therapy); akathisia, restlessness, insomnia, constipation, fatigue, and blurred vision (MDD); and nausea (short-acting IM formulation). Table 11 summarizes the tolerability information regarding rate of discontinuation due to adverse events (an overall indicator of tolerability), and the incidence of the most common adverse event, together with the calculated number needed to harm (NNH). Rates of discontinuation because of an adverse event were not higher for active medication vs placebo for the schizophrenia studies, suggesting excellent overall tolerability; for the other disease states, NNH values ranged from 17 (adjunctive use of aripiprazole for bipolar mania) to 100 (aripiprazole monotherapy for bipolar mania), representing reasonable overall tolerability for these indications.
Brexpiprazole
Brexpiprazole was launched in the United States in 2015 for 2 indications: schizophrenia and the adjunctive treatment of MDD, both in adults.19 In terms of binding, brexpiprazole has very high binding affinities to serotonin 5-HT1A (0.12 nM), adrenergic α1B (0.17 nM), dopamine D2 (0.30 nM), serotonin 5-HT2A (0.47 nM), and adrenergic α2C (0.59 nM) receptors, and high binding affinities to dopamine D3 (1.1 nM), serotonin 5-HT2B (1.9 nM), adrenergic α1D (2.6 nM), serotonin 5-HT7 (3.7 nM), and adrenergic α1A (3.8 nM) receptors.
The 1-mg/d starting dose for brexpiprazole is lower than the recommended dose range of 2 to 4 mg/d for schizophrenia or the recommended dose of 2 mg/d for MDD.19 Thus brexpiprazole requires titration. The recommended rate of titration depends on the disease state being treated. For schizophrenia, the recommended titration schedule is to increase the dose to 2 mg/d on Day 5 through Day 7, then to 4 mg/d (the maximum recommended dose) on Day 8 based on the patient’s clinical response and tolerability. For MDD, there is the option of starting at 0.5 mg/d and the titration process is slower, with dosage increases occurring at weekly intervals, and with a maximum dose of 3 mg/d.
Using the identical definition of response in persons with schizophrenia as for the aripiprazole data described above, pooling together all the available data for the recommended target dose of brexpiprazole for schizophrenia (2 to 4 mg/d) from the 2 studies listed in the product label,20,21 the percentage of responders was 46%, compared with 31% for the pooled placebo groups, yielding a NNT of 7 (95% CI 5 to 12).22
