When prescribing, what should I consider regarding doses of antipsychotic medications, oral or long-acting injectable medications?

The dosing of antipsychotic medication for patients with schizophrenia is individualized, with consideration of symptom response and side effects. However, consistent dose-response relationships have been characterized for multiple antipsychotic medications. This meta-analysis identified dosages that produce 95% efficacy for positive psychotic symptoms in the average patient. The following 95% effective doses were found for these medications: aripiprazole oral 11.5 mg/day, aripiprazole LAI (lauroxil) 463 mg every 4 weeks, asenapine oral 15.0 mg/day, brexpiprazole oral 3.4 mg/day, cariprazine oral 7.6 mg/day, haloperidol oral 6.3 mg/day, paliperidone LAI 120 mg every 4 weeks, risperidone oral 6.3 mg/day, and risperidone LAI 36.6 mg every 2 weeks. For the following medications, effectiveness continues to rise at the highest dosages studied (indicated in parentheses): iloperidone oral (24 mg/day), lurasidone oral (160 mg/day), olanzapine oral (15 mg/day), olanzapine LAI (300 mg every 2 weeks), and paliperidone oral (15 mg/day). While this provides guidance based on the average patient with persistent schizophrenia, dosages should be individualized. Clinicians should consider the pharmacodynamics and pharmacokinetic properties of each medication, side effects, patient characteristics and history, and concurrent treatments that affect medication blood levels. When increasing dosage, and especially at higher dosages, it is important to attend to side effects, including weight gain, extrapyramidal side effects, increases in prolactin levels, and QTc prolongation. Also, research suggests that there are not substantial increases in efficacy with changes to a different antipsychotic medications for reasons other than side-effects. The treatments that offer increased effectiveness in refractory illness are clozapine and perhaps long acting injectable medication.

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