Antipsychotics

Risperidone Indications: FDA-Approved and Off-Label Uses

By Flavio Guzman, MD. Risperidone is one of the oldest (and least expensive) second-generation antipsychotics. In 1993 the FDA approved it for the treatment of schizophrenia. Like most antipsychotics, risperidone is also effective for the treatment of manic and mixed episodes of bipolar I disorder. It is also one of the few antipsychotics approved for…

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Aripiprazole Indications: FDA-Approved and Off-Label Uses

Author: Flavio Guzman, MD. Aripiprazole is a second-generation (atypical) antipsychotic approved for the treatment of schizophrenia, bipolar disorder, depression and autism spectrum disorders. This article explores FDA-approved indications, dosing and evidence base for common off-label uses. FDA-approved indications Aripiprazole was originally approved in 2002 for the treatment of schizophrenia. Currently, the FDA has approved aripiprazole…

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Aripiprazole Mechanism of Action

Mechanism of Action of Aripiprazole

By Flavio Guzman, MD. As with other drugs in psychopharmacology, the mechanism of action of aripiprazole in schizophrenia has not been fully elucidated. From a pharmacological perspective, aripiprazole is different to other antipsychotic agents, as it is the only approved antipsychotic that reduces dopaminergic neurotransmission through D2 partial agonism, not D2 antagonism. The following presentation…

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Pharmacokinetics of Aripiprazole: Clinical Summary

By Flavio Guzman, MD. Formulations Tablets Orally disintegrating tablets Liquid formulation IM injection General pharmacokinetics and drug interactions Half-life aripiprazole: 75 hours dehydro-aripiprazole: 94 hours Elimination Mainly through hepatic metabolism involving two P450 enzymes: CYP3A4: dose adjustment might be needed in the presence of inhibitors or inducers. CYP2D6: dose adjustment might be needed in the…

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Quetiapine Indications: FDA-Approved and Off-label Uses

Author: Flavio Guzman, MD Quetiapine is a second generation antipsychotic approved for the treatment of schizophrenia, bipolar disorder and as adjunct treatment of major depressive disorder. This article is an overview of current FDA-approved indications and other non-approved clinical uses (the evidence for off-label uses is reviewed). FDA-Approved Indications The table below shows information on…

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Quetiapine Pharmacokinetics

Quetiapine Pharmacokinetics

By Flavio Guzman, MD. Absorption Absorbed in the gastrointestinal tract Time to reach peak blood levels: Quetiapine IR: 2 hours Quetiapine ER: 6 hours Can be taken with food Half-life: Approximately 6 hours Metabolism and drug interactions   Quetiapine is metabolized by cytochrome P450 (CYP) 3A4 to inactive metabolites, drug interactions with inhibitors and inducers…

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First-Generation Antipsychotics: An Introduction

Authors: Flavio Guzman, MD; Abimbola Farinde,PharmD First-generation antipsychotics (FGAs) are drugs used primarily for the treatment of schizophrenia and related psychotic disorders. Use of FGAs has declined in the last few years, mainly because of an increase in prescriptions of second-generation agents. Since FGAs are considerably less expensive than newer antipsychotics, they remain a valuable option…

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Mechanism of Action of Quetiapine

By Flavio Guzman, MD. Quetiapine is a second-generation antipsychotic that has affinity for D2, 5-HT2A, H1, alpha 1 and 5-HT1A receptors. Its precise mechanism of action is unknown, but according to the dopamine theory of schizophrenia, antipsychotic effects might be related to the drug’s ability to reduce dopaminergic neurotransmission in the mesolimbic pathway. Quetiapine, D2…

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The Four Dopamine Pathways Relevant to Antipsychotics Pharmacology

By Flavio Guzmán, MD This video describes the 4 dopamine pathways relevant to the mechanism of action and adverse effects of antipsychotic drugs. Presentation outline: General overview of dopaminergic pathways Mesolimbic pathway & positive symptoms of schizophrenia Mesocortical pathway: negative & cognitive symptoms Nigrostriatal pathway & EPS Tuberoinfundibular pathway & prolactin release Summary Transcript Introduction…

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Neurological side effects of antipsychotics: akathisia, dystonia and parkinsonism

This video summarizes acute neurological side effects of antipsychotics: akathisia, dystonia and parkinsonism. 1. Akathisia and Dystonia A classification of neurological side effects Akathisia ( Clinical features, a clinical video, medications that can cause akathisia and management) Acute dystonia (Clinical features, pathophysiology, management) 2. Parkinsonism Clinical features Mechanism of EPS Differences between antipsychotic induced parkinsonism and Parkinson’s…

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