Fanapt (iloperidone)

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Last reviewed · Source: First Databank (FDB) drug data

Overview

Iloperidone is considered an atypical antipsychotic agent.

Iloperidone is a piperidinyl-benzisoxazole derivative; the drug has been referred to as an atypical antipsychotic agent. Although the exact mechanism of action of iloperidone is unknown, it has been suggested that the efficacy of iloperidone is mediated through a combination of antagonist activity at central dopamine type 2 (D2) and serotonin type 2 (5-hydroxytryptamine (5-HT2)) receptors.

Iloperidone acts as an antagonist with high binding affinity for 5-HT2A, D2 and D3, and alpha1-adrenergic receptors. The drug has moderate affinity for D4, 5-HT6, and 5-HT7 receptors and low affinity for 5-HT1A, D1, and histamine H1 receptors. Iloperidone possesses no appreciable affinity for muscarinic cholinergic receptors.

Iloperidone has 2 main metabolites, P88 and P95; the affinity of the P88 metabolite is generally equal to or less than that of the parent compound while the P95 metabolite demonstrates affinity for 5-HT2A and alpha1A-, alpha1B-, alpha1D-, and alpha2C-adrenergic receptors.

Iloperidone is well absorbed following oral administration of the tablets, with peak plasma concentrations occurring within 2-4 hours. Steady-state plasma concentrations of iloperidone and its two main metabolites, P88 and P95, are reached within 3-4 days. Administration with a high-fat meal did not significantly impact maximum plasma concentrations or AUC of iloperidone or its metabolites; time to maximum concentration was delayed by 1, 2, and 6 hours for iloperidone, P88, and P95, respectively.

At therapeutic concentrations, iloperidone and its metabolites (P88 and P95) are approximately 97 and 92% bound to plasma proteins, respectively. Iloperidone is primarily metabolized by carbonyl reduction, cytochrome P-450 (CYP) isoenzyme 2D6-mediated hydroxylation, and CYP3A4-mediated O-demethylation; P88 and P95 undergo further oxidation and/or conjugation with glucuronic acid. The P88 metabolite penetrates the CNS and is thought to contribute to the drug's antipsychotic activity whereas the P95 metabolite does not readily penetrate the CNS and primarily contributes to the adverse effect profile of the drug.

The mean elimination half-lives of iloperidone, P88, and P95 are 18, 26, and 23 hours, respectively, in extensive metabolizers of CYP2D6 and 33, 37, and 31 hours, respectively, in poor metabolizers of CYP2D6. The majority of radiolabeled iloperidone was recovered in the urine (mean of 58.2 and 45.1% in extensive and poor metabolizers of CYP2D6, respectively), with feces accounting for 19.9% (extensive metabolizers) and 22.1% (poor metabolizers) of the radiolabeled dose.

USES: This medication is used to treat certain mental/mood disorders (such as schizophrenia, bipolar disorder). Iloperidone belongs to a class of drugs known as atypical antipsychotics. It works by helping to restore the balance of certain natural substances in the brain.

Generic name: iloperidone
Pronunciation: (EYE-loe-PER-i-done)

Reference product & biosimilars

No reference, biosimilar or interchangeable associated with this drug.

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Indications

The following indications are listed for Fanapt:

  • Mixed Bipolar I Disorder
  • Schizophrenia

Also known as: Dementia Praecox, Parergasia.

Dosing

If iloperidone is used concomitantly with a strong cytochrome P-450 (CYP) 2D6 inhibitor (e.g., fluoxetine, paroxetine), reduce the dosage of iloperidone by 50%. If the strong CYP2D6 inhibitor is discontinued, increase the dosage of iloperidone to the previous dosage.

If iloperidone is used concomitantly with a strong CYP3A4 inhibitor (e.g., ketoconazole, clarithromycin), reduce the dosage of iloperidone by 50%. If the strong CYP3A4 inhibitor is discontinued, increase the dosage of iloperidone to the previous dosage.

If iloperidone is used concomitantly with strong CYP2D6 and strong CYP3A4 inhibitors, reduce the dosage of iloperidone by 50%. If both CYP2D6 and CYP3A4 inhibitors are discontinued, increase the dosage of iloperidone to the previous dosage.

Drug interactions

Iloperidone is metabolized principally by cytochrome P-450 (CYP) isoenzymes 3A4 and 2D6.

Iloperidone is not a substrate or inhibitor of CYP isoenzymes 1A1, 1A2, 2A6, 2B6, 2C8, 2C9, or 2E1; it is also not a substrate of CYP2C19, and not an inducer of CYP isoenzymes 1A2, 2C8, 2C9, 2C19, 3A4, or 3A5.

Iloperidone and its active metabolite P88 are not substrates of P-glycoprotein (P-gp). Iloperidone is a weak P-gp inhibitor.

Contraindications

*Known hypersensitivity to the product; anaphylaxis, angioedema, and other hypersensitivity reactions reported.

Adverse reactions

Adverse effects occurring in clinical trials in 5% or more of patients receiving short-term iloperidone therapy for schizophrenia and at a frequency at least twice that reported among patients receiving placebo include dizziness, fatigue, dry mouth, nasal congestion, tachycardia, orthostatic hypotension, somnolence, and weight gain.

Adverse effects occurring in clinical trials in 5% or more of patients receiving short-term iloperidone therapy for bipolar mania and at a frequency at least twice that reported among patients receiving placebo include tachycardia, dizziness, dry mouth, increased hepatic enzymes, nasal congestion, weight gain, hypotension, and somnolence.

Precautions

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ICD codes

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Formulary status

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Last reviewed · Source: First Databank (FDB) drug data