Iloperidone

• Schizophrenia
• Psychosis
• Antipsychotic Therapy
• Mental Health Treatment

Iloperidone is an atypical antipsychotic medication used for the treatment of schizophrenia in adults. This medication has a unique receptor binding profile and requires gradual dose titration, but offers benefits including low propensity for extrapyramidal symptoms and weight gain compared to some other antipsychotics.

Mechanism of Action

Iloperidone is a piperidinyl-benzisoxazole derivative with high affinity for dopamine D2 and D3 receptors, serotonin 5-HT2A receptors, and norepinephrine alpha-1 receptors. The therapeutic efficacy in schizophrenia is thought to be mediated primarily through combined antagonism of dopamine D2 and serotonin 5-HT2A receptors. The 5-HT2A antagonism may mitigate D2 antagonism-related extrapyramidal symptoms and enhance dopamine release in the prefrontal cortex. The high alpha-1 adrenergic antagonism necessitates gradual dose titration to minimize orthostatic hypotension.

Available Formulations

Iloperidone is available as oral tablets in 1 mg, 2 mg, 4 mg, 6 mg, 8 mg, 10 mg, and 12 mg strengths. A titration pack is available containing tablets in increasing doses to facilitate the required slow titration. The tablets can be taken with or without food.

Medical Uses

Iloperidone is FDA-approved for the treatment of schizophrenia in adults. Clinical trials demonstrated efficacy in reducing positive and negative symptoms of schizophrenia, as measured by improvement in Positive and Negative Syndrome Scale (PANSS) scores. Due to the required titration period, iloperidone may not be ideal for acute agitation requiring rapid treatment.

Dosing Guidelines

Due to significant orthostatic hypotension risk, iloperidone must be titrated gradually. The recommended starting dose is 1 mg twice daily, increased daily in 2 mg increments (twice daily) to a target dose of 6-12 mg twice daily (12-24 mg/day). Maximum recommended dose is 12 mg twice daily. If treatment is interrupted for more than 3 days, re-titration is recommended. For CYP2D6 poor metabolizers or patients taking strong CYP2D6 or CYP3A4 inhibitors, the dose should be reduced by half.

Important Safety Information

Iloperidone carries a boxed warning for increased mortality in elderly patients with dementia-related psychosis (not approved for this use). Significant QT prolongation occurs; iloperidone should be avoided in patients with known QT prolongation, those taking other QT-prolonging medications, or those with relevant cardiac risk factors. Orthostatic hypotension can be severe during initial titration. Other risks include neuroleptic malignant syndrome, tardive dyskinesia, metabolic effects, hyperprolactinemia, and leukopenia/neutropenia.

Drug Interactions

CYP2D6 inhibitors (paroxetine, fluoxetine, quinidine) and CYP3A4 inhibitors (ketoconazole, clarithromycin) increase iloperidone levels; reduce dose by half when combined. CYP3A4 inducers (carbamazepine, rifampin) may decrease levels. Avoid use with other QT-prolonging medications (certain antiarrhythmics, antipsychotics, fluoroquinolones, macrolides). Additive effects with CNS depressants and antihypertensives may occur.

Special Populations

There are no adequate studies in pregnant women. Neonates exposed to antipsychotics during the third trimester may experience extrapyramidal or withdrawal symptoms. Iloperidone is excreted in rat milk; caution is advised during breastfeeding. Safety and efficacy have not been established in pediatric patients. Elderly patients may be more sensitive to orthostatic hypotension and adverse effects. CYP2D6 poor metabolizers have 80% higher exposure; reduce dose by half. No dose adjustment is needed for renal impairment. Use is not recommended in patients with hepatic impairment.