This review from the Quality Use of Medicines service agency for Australia’s National Medicines Policy examines the evidence on asenapine in the treatment of schizophrenia and bipolar I disorder and makes note of the following:

• Asenapine has a similar spectrum of benefits and harms to that of other antipsychotics.

• Trial data demonstrate efficacy up to 52 weeks in schizophrenia and 12 weeks in bipolar mania and mixed episodes.

• In one 52-week schizophrenia and schizoaffective disorder trial, olanzapine reduced PANSS symptom scores slightly more than asenapine (–27.5 vs –21.0, p<0.0001). More people who received asenapine had treatment-related extrapyramidal symptoms (14% vs. 7%), but fewer had treatment-related weight gain of ≥7% of baseline (12% vs. 29%)

The review concludes that “asenapine wafers may be useful in schizophrenia or bipolar disorder when established antipsychotics are relatively contraindicated. Asenapine may cause less QTc prolongation, antimuscarinic effects, hyperprolactinaemia and weight gain than some other antipsychotics, but more sedation and extrapyramidal symptoms.” It recommeds that clinicians consider antipsychotics with more extensive clinical data before asenapine in schizophrenia; whilst in bipolar disorder, olanzapine, quetiapine and risperidone depot injection have more extensive evidence for relapse prevention; and clozapine is the first choice for treatment resistant schizophrenia.

Asenapine is expected to be launched in the UK in the first quarter of 2012.