Olanzapine Study Guide
Healthcare providers are required to have a vast experience and knowledge of medications before prescribing them to patients. The medications are many and require years of experience to understand them and prescribe them without any problems.
A study guide is a summarized document detailing essential aspects such as drug class, interactions, indications, pharmacokinetics, and pharmacodynamics. The information is vital when making a clinical diagnosis and managing a patient. This study guide focuses on olanzapine, a psychiatric medication used in patients with schizophrenia and schizophrenia spectrum disorders.
Olanzapine is an FDA-approved drug for treating schizophrenia in patients above 13 years and bipolar disorder for both mixed and manic episodes (Stern et al., 2016). The medication is also used alongside fluoxetine (an SSRI) in patients above ten years with treatment-resistant depression in bipolar disorder type 1. It is also prescribed for bipolar or schizophrenia patients with acute agitation.
The drug use in children below 13 years in the conditions mentioned above is off-label (Stern et al., 2016). Other off-label uses of the medication include treating agitation in dementia, PTSD, Tourette Syndrome, chemotherapy-induced nausea and vomiting, delirium, and anorexia nervosa (Thomas & Saadabadi, 2021). Saudemont et al. (2020) note that the antiemetic emetic effects are owed to its dopamine and serotonin receptor blockade.
Olanzapine is a second-generation antipsychotic medication
Mechanism of Action
Olanzapine works primarily on the dopamine and serotonin receptors. It binds to the dopamine receptors in the mesolimbic pathway and prevents post-synaptic receptor actions. This action reduces the positive symptoms such as hallucinations, delusions, and disorganized speech, thought, and behavior hence its FDA-approved and off-label uses.
The medication is also a serotonin antagonist in the brain’s frontal cortex, an action that causes a reduction in positive symptoms such as negative symptoms such as anhedonia, alogia, flat affect, avolition, and inattentiveness (Thomas & Saadabadi, 2021)
Pharmacodynamics entails how a drug affects the body, and the pharmacodynamics of olanzapine are discussed under subheadings; mechanism of action, drug side effects, drug interactions, comorbidities, and contraindications.
It has 10000 liters volume of distribution, and 93% of the drug is bound to plasma proteins, albumin, and alpha-1 glycoprotein. Olanzapine undergoes extensive metabolizes in the liver by 1A2 and minorly 2D6 liver enzymes. The amount of excreted drug is usually about 7% excreted, 53% in urine, and 30% in feces (Thomas & Saadabadi, 2021). Dose adjustment for renal problems is not necessary for liver problems, and it takes about 25 days for the medication to exit the system wholly.
The half-life of a drug is the amount of time it takes the plasma level of a drug to reduce by half. The half-life is vital in determining dose frequency, toxicity, and therapeutically effective doses for patients. Olanzapine has an average half-life of 30 hours (between 21-58 hours). Daily administration achieves peak plasma concentration in one week.
Appropriate dosing, administration route, and any considerations for dosing alterations
The initial dose of the drug is 5-10mg orally daily, and the maintenance dose is 150 mg IM every two weeks OR 300 mg IM every 4 weeks or 20mg orally daily (Stern et al. l., 2016). Olanzapine doses are available in oral and injectable formulations. The drug is also available in disintegrating tablets for patients with poor tolerance to the drug.
However, the bioavailability between the disintegrating tablets and the oral route is insignificant. The injectable route is available for patients with non-compliance and should not be used as a replacement for long-term antipsychotic medications. The oral tablets are available in 2.5 mg, 5 mg, 7.5 mg, 10 mg, 15 mg, and 20 mg doses, while the injectable route is available as a 5mg/ml drug.
Dose adjustment is necessary for renal but not for liver disorders. Olanzapine doses are also adjusted to over 20mg daily when the medication achieves partial symptom remission. Drugs, medications that affect the CYP1A2 or glucuronyl transferase enzyme inhibitors, and inducers affect olanzapine metabolism, and dose adjustments to increase or decrease it is necessary (Mefta et al., 2020).
Olanzapine’s side effects include weight gain and metabolic syndrome. Olanzapine impairs glucose tolerance and decreases insulin sensitivity, causing sequelae that lead to these undesirable effects. Its MOA, dopamine receptors blockade, leads to symptoms such as extrapyramidal effects, akathisia, and tardive dyskinesia. However, the severity of these symptoms is lesser than that of first-generation antipsychotics. Blood abnormalities reported include neutropenia and thrombocytopenia.
The medication is contraindicated in patients with hypersensitivity to the drug or other second-generation antipsychotics. Elderly patients with dementia and psychotic symptoms should not receive the medication due to an increased risk for early mortality. The medication is used with caution in obese and diabetic patients due to the medication side effects that include weight gain and metabolic syndrome.
The drug’s side effects cause severe weight gain and lipid and glucose metabolic dysfunction (Kang et al., 2022). Kang et al. (2022) show that other side effects, such as extrapyramidal effects and hematologic changes, are minor and rare, but these metabolic changes are severe and the leading causes of the drug’s withdrawal.
Lab and Diagnostic Monitoring
Blood sugars: FBS and RBS (Thomas & Saadabadi, 2021)
Special Population Considerations
Olanzapine dose adjustment is necessary for children, and a dose that exceeds 0.5mg/kg is potentially toxic (Merino et al., 2020). The drug is not FDA-approved for children. The medication is also contraindicated in elderly patients with dementia and bipolar disorder psychosis.
The oral dose should also be avoided in patients with dementia and other problems that interfere with drug adherence. Olanzapine has been found to increase suicidal behavior and ideations, and the tendency is high among males between ages 30-39; patients should thus be assessed for suicidal behaviors and ideations (Shah & Khan, 2019).
Legal and Ethical Considerations
When administering olanzapine, it is important to consider age, comorbidities, and any other considerations. The drug should be used when it is FDA-approved or as second; in off-label uses. The drug should be used in ethically justified situations, such as agitation management in pregnancy, despite the risk when the benefits outweigh the consequences (Nguyen et al., 2022).
Pertinent Patient Education
Patients on olanzapine should be educated together with their families. The education includes the dosages, especially oral drugs, and appointments for the injections. They should also be educated on drug side effects, including weight gain, to ensure prompt reporting and management.
Olanzapine is an FDA-approved medication for schizophrenia and bipolar disorders for individuals above thirteen years. The drug acts on dopamine and serotonin receptors, hence its effectiveness in treating positive and negative psychotic symptoms.
Due to its side effects, it is used with precaution in individuals with suicidal behaviors, obesity, and diabetes. The most severe effects are weight gain and metabolic syndrome; hence monitoring entails the lipid profile and other metabolic indicators. Olanzapine can be used in both oral and IM injections, and the method used depends on patient factors.
Kang, D., Lu, J., Liu, W., Shao, P., & Wu, R. (2022). Association between olanzapine concentration and metabolic dysfunction in drug-naive and chronic patients: similarities and differences. Schizophrenia, 8(1), 1-9. https://doi.org/10.1038/s41537-022-00211-5
Meftah, A. M., Deckler, E., Citrome, L., & Kantrowitz, J. T. (2020). New discoveries for an old drug: a review of recent olanzapine research. Postgraduate Medicine, 132(1), 80-90. https://doi.org/10.1080/00325481.2019.1701823
Merino, D., Fernandez, A., Gérard, A. O., Ben Othman, N., Rocher, F., Askenazy, F., … & Thümmler, S. (2022). Adverse Drug Reactions of Olanzapine, Clozapine, and Loxapine in Children and Youth: A Systematic Pharmacogenetic Review. Pharmaceuticals, 15(6), 749. https://doi.org/10.3390/ph15060749
Nguyen, M. T., Rafla-Yuan, E., Boyd, E., Mccullough, L. B., Chervenak, F. A., & Dossett, E. C. (2022). Ethical considerations in the treatment of chronic psychosis in a periviable pregnancy. Clinical Ethics, 14777509221096623. https://doi.org/10.1177/14777509221096623
Saudemont, G., Prod’Homme, C., Da Silva, A., Villet, S., Reich, M., Penel, N., & Gamblin, V. (2020). The use of olanzapine as an antiemetic in palliative medicine: a systematic review of the literature. BMC Palliative Care, 19(1), 1-11. https://doi.org/10.1186/s12904-020-00559-4
Sher, L., & Kahn, R. S. (2019). Suicide in schizophrenia: an educational overview. Medicina, 55(7), 361. https://doi.org/10.3390/medicina55070361
Stern, T. A., Favo, M., Wilens, T. E., & Rosenbaum, J. F. (2016). Massachusetts General Hospital psychopharmacology and neurotherapeutics. Elsevier.
Thomas, K., & Saadabadi, A. (2021). Olanzapine. In StatPearls [Internet]. StatPearls Publishing.