Antipsychotic & Related Medication Study Guide

• Aripiprazole (Abilify)

• FDA Indications: Comprehensive treatment for schizophrenia, which can cause severe disruptions in cognition and emotion. It is also effective for Bipolar I disorder, specifically during manic or mixed episodes. Additionally, it serves as an adjunctive treatment for Major Depressive Disorder (MDD) where patients show inadequate response to traditional antidepressants. Aripiprazole is also indicated for managing irritability associated with Autism and for Tourette disorder, which causes involuntary tics and sounds.

• Common Side Effects: Users frequently experience akathisia (a state of uncontrollable restlessness), insomnia which can affect overall mental health, anxiety that can exacerbate symptoms of the underlying condition, nausea that may lead to non-compliance, and headache which is a common complaint among patients.

• Serious Adverse Effects: There is a potential risk for Neuroleptic Malignant Syndrome (NMS), a life-threatening condition marked by muscle rigidity and fever, Tardive Dyskinesia (TD), an involuntary movement disorder that can be permanent, impulse control disorders such as pathological gambling or shopping that can significantly impact personal and financial aspects of life, and increased suicidality which necessitates careful monitoring, especially in adolescents.

• Drug Interactions: Key interactions occur with drugs that are processed by the CYP2D6 and CYP3A4 metabolic pathways, necessitating caution when prescribing alongside these processes due to the risk of altered drug efficacy or increased toxicity.

• Laboratory and Clinical Monitoring: Regular monitoring of Weight/BMI is crucial as weight gain can lead to metabolic disorders. Monitoring lipid levels helps assess cardiovascular health, glucose levels, and $A1c$ for diabetes management, as well as Blood Pressure (BP) to detect any fluctuations. Screening for Extrapyramidal Symptoms (EPS) using the Abnormal Involuntary Movement Scale (AIMS) is also essential to catch side effects early.

• Potency: Second Generation, Low Potency

• Receptor Interactions: Aripiprazole primarily acts as a partial agonist at the dopamine D2 receptor and serotonin 5-HT1A receptor while antagonizing the serotonin 5-HT2A receptor.

Brexpiprazole (Rexulti)

• FDA Indications: This medication is equally indicated for schizophrenia, similar to Aripiprazole, and offers an adjunctive treatment for MDD, enhancing the therapeutic efficacy of existing antidepressants. Furthermore, it addresses agitation associated with Alzheimer’s dementia, allowing for better management of behavioral symptoms.

• Common Side Effects: Known for causing weight gain, which can have long-term ramifications for metabolic health, akathisia which impacts the patient's comfort and ability to function, and sedation that can impair daily activities.

• Serious Adverse Effects: Risks include NMS, TD, and development of metabolic syndrome, all of which require healthcare providers to remain vigilant.

• Drug Interactions: Users need to exercise caution when using Brexpiprazole alongside CYP2D6 and CYP3A4 inhibitors as they can alter Brexpiprazole's metabolism and introduce significant side effects.

• Laboratory and Clinical Monitoring: Ongoing assessment of weight, glucose, and lipid levels are necessary to avert complications associated with metabolic syndrome, as well as using AIMS to screen for movement disorders continuously.

• Potency: Second Generation, Low Potency

• Receptor Interactions: Brexpiprazole functions as a partial agonist at the dopamine D2 and serotonin 5-HT1A receptors and as an antagonist at the serotonin 5-HT2A receptor.

Chlorpromazine (Thorazine)

• FDA Indications: Utilized for the treatment of schizophrenia, Chlorpromazine is also effective in managing severe nausea and vomiting, particularly in the context of chemotherapy or post-operative recovery, and the treatment of intractable hiccups.

• Common Side Effects: Highly associated with sedation, which can hinder daily activities, orthostasis leading to fainting or falls, and a range of anticholinergic effects like dry mouth and blurred vision that can severely affect quality of life.

• Serious Adverse Effects: There is an elevated risk of QT prolongation which can lead to serious cardiac arrhythmias, and agranulocytosis, a potentially life-threatening condition where white blood cell counts drop dangerously low, cholestatic jaundice contributing to liver dysfunction, and NMS, all requiring stringent monitoring.

• Drug Interactions: Dangerous interactions can occur with other QT-prolonging medications and CNS depressants, highlighting the need for thorough medication reconciliation.

• Laboratory and Clinical Monitoring: Requires comprehensive monitoring including Complete Blood Count (CBC) to track white blood cell levels, Liver Function Tests (LFTs) to evaluate liver health, Electrocardiogram (ECG) for cardiac function, and Blood Pressure (BP) assessments.

• Potency: First Generation, Low Potency

• Receptor Interactions: Chlorpromazine acts as an antagonist at multiple receptors, including dopamine D2, serotonin 5-HT2A, and adrenergic receptors, which contributes to its antipsychotic effects.

Haloperidol (Haldol)

• FDA Indications: Primarily prescribed for the management of schizophrenia, acute psychosis episodes, and acute agitation, especially in those requiring immediate behavioral control.

• Common Side Effects: There is a significant risk of experiencing Extrapyramidal Symptoms (EPS) including dystonia (muscle contractions), akathisia, and parkinsonism, disrupting patient stability.

• Serious Adverse Effects: Concerns include TD, NMS, and QT prolongation which necessitates pre-treatment ECG assessments and careful ongoing cardiac monitoring.

• Drug Interactions: Potential interactions with other medications known to prolong the QT interval, thereby complicating clinical management.

• Laboratory and Clinical Monitoring: Continuous ECGs, serum electrolyte monitoring (e.g., potassium, magnesium), and EPS assessments using AIMS to identify and address side effects promptly.

• Potency: First Generation, High Potency

• Receptor Interactions: Haloperidol primarily acts as a strong antagonist at the dopamine D2 receptor, leading to its antipsychotic effects.

Clozapine (Clozaril): Management and Specialized Monitoring

• FDA Indications: Specifically recognized for treatment-resistant schizophrenia, especially in patients who have failed multiple antipsychotic trials, and it has been shown to reduce the risk of recurrent suicidal behavior in high-risk patients.

• Common Side Effects: Notable for causing significant sedation, sialorrhea (excessive drooling), constipation, and considerable weight gain that can lead to metabolic complications if not addressed.

• Serious Adverse Effects: Clozapine has a high-risk profile, including agranulocytosis requiring close monitoring of Absolute Neutrophil Count (ANC), myocarditis, a serious inflammation of the heart muscle, seizures, and paralytic ileus that can lead to bowel obstruction, as well as NMS requiring immediate intervention.

• Drug Interactions: Smoking reduces clozapine blood levels necessitating dosage adjustments; conversely, fluvoxamine significantly increases clozapine levels which can lead to toxicity.

• Laboratory and Clinical Monitoring: Strict monitoring of ANC through CBC, glucose monitoring for potential diabetes, lipid panels to assess cardiovascular risk, and cardiac markers like troponin and C-Reactive Protein (CRP) to detect early signs of myocarditis.

• Potency: Second Generation, Low Potency

• Receptor Interactions: Clozapine is a unique antagonist at multiple receptors, including dopamine D1 and D2 receptors, serotonin 5-HT2A and 5-HT2C receptors, and other neuroreceptors, which helps in its effectiveness for treatment-resistant cases.

Additional Second-Generation (Atypical) Antipsychotics

Lurasidone (Latuda)

• FDA Indications: Approved for schizophrenia and the depressive phase of Bipolar disorder, providing an effective treatment option during depressive episodes.

• Common Side Effects: Users often report akathisia, nausea, and sedation, which can be problematic in daily functioning.

• Serious Adverse Effects: Risks involve NMS and TD, necessitating careful management.

• Drug Interactions: Strong CYP3A4 inhibitors or inducers are strictly contraindicated, highlighting the importance of assessing concurrent medications. (ex. Ketoconazole: An antifungal medication that can significantly inhibit CYP3A4 activity.

• Itraconazole: Another antifungal that has a strong inhibitory effect on CYP3A4.

• Clarithromycin: An antibiotic that can reduce the metabolism of other drugs metabolized by CYP3A4.

• Nefazodone (Serzone): An antidepressant that is known to strongly inhibit CYP3A4.

• Ritonavir: An antiretroviral that can boost the levels of other drugs by inhibiting CYP3A4.

• Grapefruit juice: Often overlooked, it contains compounds that can inhibit CYP3A4 activity in the intestines, affecting drug metabolism.).

• Ketoconazole: An antifungal medication that is a potent inhibitor of CYP3A4, significantly impacting the clearance of coadministered drugs.

• It should be taken with a meal (at least 350 calories) to ensure optimal absorption and efficacy.

• Laboratory and Clinical Monitoring: Close monitoring of weight, glucose and lipid panels, alongside AIMS for movement disorders is critical for holistic care.

• Potency: Second Generation, Low Potency

• Receptor Interactions: Lurasidone acts as an antagonist at dopamine D2 and serotonin 5-HT2A receptors and a partial agonist at serotonin 5-HT1A receptors.

Olanzapine (Zyprexa)

• FDA Indications: Indicated for schizophrenia, bipolar disorder, and treatment-resistant depression, with applications in acutely manic or mixed episodes.

• Common Side Effects: Heavily associated with weight gain, sedation, and increased appetite, leading to potential long-term health concerns.

• Serious Adverse Effects: Risks include metabolic syndrome, Diabetic Ketoacidosis (DKA), TD, and NMS, which necessitate proactive intervention strategies.

• Drug Interactions: Smoking lowers olanzapine blood levels and interactions with other CNS depressants must be monitored closely for safety.

• Laboratory and Clinical Monitoring: Frequent assessments of Weight/BMI, glucose and $A1c$ levels, and lipids are essential to mitigate risks associated with long-term treatment.

• Potency: Second Generation, Low Potency

• Receptor Interactions: Olanzapine primarily acts as an antagonist at dopamine D2 and serotonin 5-HT2A receptors, alongside activity at other pathways.

• Paliperidone (Invega)

• FDA Indications: Approved for the treatment of schizophrenia and schizoaffective disorder, and for the maintenance treatment of schizophrenia.

• Common Side Effects: Akathisia, sedation, restlessness, and headache.

• Unique Side Effects: May cause hyperprolactinemia (elevated prolactin levels) leading to issues like galactorrhea or amenorrhea.

• Serious Adverse Effects: Neuroleptic Malignant Syndrome (NMS), Tardive Dyskinesia (TD), and cardiovascular events including QT prolongation.

• Drug Interactions: Caution with other CNS depressants and drugs that affect the metabolism of CYP2D6 and CYP3A4.
  CYP2D6 Inhibitors: These inhibit the metabolism of drugs processed by this enzyme, potentially leading to increased drug levels and effects.

  • Examples include:

  • Fluoxetine (Prozac)

  • Paroxetine (Paxil)

  • Bupropion (Wellbutrin)

  • Quinidine

• CYP2D6 Inducers: These increase the activity of the enzyme, which can lower the effectiveness of certain medications.

  • Examples include:

  • Rifampicin (Rifampin)

  • Phenobarbital

  • Dexamethasone

• CYP3A4 Inhibitors: These can lead to increased concentrations of drugs metabolized by CYP3A4.

  • Examples include:

  • Ketoconazole

  • Itraconazole

  • Nefazodone

  • Clarithromycin

• CYP3A4 Inducers: These can decrease the levels of drugs that rely on CYP3A4 for metabolism, potentially resulting in therapeutic failure.

  • Examples include:

  • St. John's Wort

  • Phenytoin

  • Carbamazepine

• Laboratory and Clinical Monitoring: Regular monitoring of weight, glucose, and lipid levels, along with blood pressure checks.

• Potency: Second Generation, Moderate Potency.

• Receptor Interactions: Acts primarily as an antagonist at dopamine D2 and serotonin 5-HT2A receptors.

Perphenazine (Trilafon)

• FDA Indications: Effective for managing schizophrenia and severe agitation.

• Common Side Effects: Sedation, dry mouth, dizziness, and orthostatic hypotension.

• Unique Side Effects: Can cause significant sedation and extrapyramidal symptoms compared to atypical antipsychotics.

• Serious Adverse Effects: QT prolongation, agranulocytosis, and NMS requiring vigilant monitoring.

• Drug Interactions: Increased risk of CNS depression with other depressants, and caution with QT-prolonging agents.

• Laboratory and Clinical Monitoring: Routine CBC to monitor for agranulocytosis, along with ECG for QT interval assessment.

• Potency: First Generation, Moderate Potency.

• Receptor Interactions: Primarily antagonizes D2 dopamine receptors and has some action at serotonin receptors.

Quetiapine (Seroquel)

• FDA Indications: Indicated for schizophrenia, bipolar disorder (both manic and depressive episodes), and as an adjunct for Major Depressive Disorder.

• Common Side Effects: Sedation, weight gain, orthostatic hypotension, and metabolic changes.

• Unique Side Effects: Significant sedation which may be sought after in some patients for sleep.

• Serious Adverse Effects: Risk of metabolic syndrome, TD, NMS, and increased suicidal thoughts in young adults.

• Drug Interactions: Caution with other CNS depressants, and CYP3A4 substrates.

• Laboratory and Clinical Monitoring: Monitor weight, fasting glucose, and lipid profiles periodically.

• Potency: Second Generation, Low Potency.

• Receptor Interactions: Acts as an antagonist at D2 and 5-HT2A receptors, with additional effects on histaminergic pathways leading to sedation.

Risperidone (Risperdal)

• FDA Indications: Approved for the treatment of schizophrenia, bipolar disorder, and irritability associated with autistic disorder.

• Common Side Effects: Weight gain, sedation, EPS, and hyperprolactinemia.

• Unique Side Effects: Can significantly elevate prolactin levels leading to reproductive effects.

• Serious Adverse Effects: NMS, TD, metabolic syndrome, and prolonged QT interval.

• Drug Interactions: Interactions with drugs metabolized by CYP2D6 and caution with other medications causing sedation.

• Laboratory and Clinical Monitoring: Monitor weight, glucose, lipid levels, and prolactin levels.

• Potency: Second Generation, Moderate Potency.

• Receptor Interactions: Antagonizes D2 dopamine receptors and 5-HT2A receptors.

Xanomeline/Tropsium Chloride (Cobenfy)

• FDA Indications: Approved for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and frequency.

• Common Side Effects: Dry mouth, constipation, blurred vision, dizziness, and sedation.

• Unique Side Effects: Anticholinergic effects due to its mechanism of action.

• Serious Adverse Effects: Risk of NMS and prolonged QT interval, though less common than with traditional antipsychotics.

• Drug Interactions: Should be used with caution in patients taking other anticholinergics and in conjunction with drugs that prolong QT interval.

• Laboratory and Clinical Monitoring: Regular assessment of urinary symptoms and side effect profile.

• Potency: Variable, does not fit cleanly within standard potency classifications of antipsychotics.

• Receptor Interactions: Acts primarily on muscarinic receptors, which mediates its effects on urinary incontinence.

Cobenfy, while primarily approved for the treatment of overactive bladder, can also be considered in the context of mental health due to its neuroactive properties. There are several aspects to consider regarding its potential use in psychiatry:

• Mechanism of Action: Cobenfy acts primarily on muscarinic acetylcholine receptors in the brain, which play a significant role in modulating neurotransmission and cognitive functions such as learning, memory, and emotional regulation. This modulation can indirectly influence behaviors associated with mental health conditions.

• Agitation and Behavior: Given its ability to affect the central nervous system, Cobenfy may have applications in managing agitation or behavioral symptoms in conditions like dementia or severe psychiatric disorders, where overactive bladder symptoms may coexist with behavioral disturbances.

• Research and Trials: Although not traditionally categorized as a psychotropic medication, ongoing research and clinical trials are exploring its efficacy for conditions where cholinergic modulation could be beneficial, including anxiety and mood disorders. The exploration of such off-label uses often emerges when existing treatments fail to provide adequate relief.

• Limitations: It is essential to note that Cobenfy is not a first-line treatment for any psychiatric condition, and its use in mental health would generally be considered in specialized cases or in conjunction with other therapies. The potential benefits must be weighed against side effects, which include anticholinergic effects that can impact cognition and mood.

• Patient Management: Healthcare providers may monitor patients' mental health symptoms when prescribing Cobenfy for overactive bladder, recognizing that improvements in urinary symptoms can have positive secondary effects on emotional well-being, particularly in older adults dealing with multiple health issues.