Drug Guide
Olanzapine; Samidorphan L-malate
Classification
Therapeutic: Antipsychotic, Mood Stabilizer
Pharmacological: Atypical Antipsychotic
FDA Approved Indications
- Schizophrenia
- Bipolar I disorder (manic or mixed episodes, depression)
Mechanism of Action
Olanzapine acts as an antagonist at multiple neurotransmitter receptors in the brain, including dopamine D2 and serotonin 5-HT2A receptors. Samidorphan is an opioid antagonist that mitigates olanzapine-induced weight gain by modulating opioid receptor activity, particularly at the mu-opioid receptor.
Dosage and Administration
Adult: Typically, the starting dose is 10 mg olanzapine with 20 mg samidorphan once daily, adjusted as needed; specific dosing varies based on condition and response.
Pediatric: Not established for use in pediatric patients.
Geriatric: Use with caution; start at lower doses and monitor closely due to increased sensitivity and risk of adverse effects.
Renal Impairment: Adjust dose cautiously; no specific guidelines, consider renal function.
Hepatic Impairment: Adjust dose cautiously; no specific guidelines, monitor liver function.
Pharmacokinetics
Absorption: Well absorbed orally, peak plasma concentrations in approximately 5-8 hours.
Distribution: Widely distributed in body tissues; high affinity for adipose tissue.
Metabolism: Metabolized primarily in the liver via CYP1A2 and CYP2D6 pathways.
Excretion: Excreted mainly in urine and feces.
Half Life: Olanzapine: approximately 21-54 hours; Samidorphan: approximately 11-13 hours.
Contraindications
- Hypersensitivity to olanzapine, samidorphan, or any component of the formulation.
Precautions
- Use with caution in patients with dementia-related psychosis due to increased mortality risk; monitor for metabolic changes, extrapyramidal symptoms, and neuroleptic malignant syndrome.
Adverse Reactions - Common
- Weight gain (Common)
- Sedation (Common)
- Dizziness (Common)
- Dry mouth (Common)
Adverse Reactions - Serious
- Neuroleptic malignant syndrome (Rare)
- Hyperglycemia and diabetic ketoacidosis (Uncommon)
- QT prolongation (Uncommon)
- Tardive dyskinesia (Uncommon)
Drug-Drug Interactions
- CNS depressants (additive sedation)
- Other drugs that prolong QT interval
- Antidiabetic medications (altered glucose control)
Drug-Food Interactions
N/ADrug-Herb Interactions
N/ANursing Implications
Assessment: Monitor mental status, metabolic parameters, electrolytes, and cardiovascular status before and during therapy.
Diagnoses:
- Risk for metabolic syndrome
- Risk for falls due to sedation
- Impaired physical mobility
Implementation: Administer with food to minimize orthostatic hypotension; monitor weight and metabolic parameters regularly.
Evaluation: Assess symptom control and monitor for adverse effects, including metabolic disturbances and extrapyramidal symptoms.
Patient/Family Teaching
- Take medication as prescribed and do not stop abruptly.
- Report any signs of metabolic changes, movement disorders, or allergic reactions.
- Be cautious when operating machinery or driving until response is known.
Special Considerations
Black Box Warnings:
- Increased mortality in elderly patients with dementia-related psychosis.
Genetic Factors: Patients with CYP1A2 polymorphisms may metabolize olanzapine differently, affecting drug levels.
Lab Test Interference: May increase blood glucose, lipid levels, and prolactin levels; monitor accordingly.
Overdose Management
Signs/Symptoms: Drowsiness, agitation, tachycardia, severe hypotension, extrapyramidal symptoms, seizures.
Treatment: Supportive care; monitor vital signs; consider gastrointestinal decontamination if ingestion was recent; manage symptoms symptomatically.
Storage and Handling
Storage: Store at room temperature, 20°C to 25°C (68°F to 77°F); protected from light and moisture.
Stability: Stable under recommended storage conditions until expiration date.