PREXAL 10MG TAB

Indications

Approved Uses

Schizophrenia; Bipolar I disorder-acute manic or mixed episodes; Maintenance treatment of bipolar I disorder (including relapse prevention after response to acute mania).

Off-Label Uses

Common off-label uses include delirium-related agitation (especially in medically ill), chemotherapy-induced nausea/vomiting (including as part of antiemetic regimens), behavioral/psychological symptoms of dementia (not recommended routinely; boxed warning for mortality), anorexia/cachexia-related appetite stimulation, and adjunctive use in treatment-resistant depression (distinct from the approved olanzapine/fluoxetine combination product in some jurisdictions).

Dosage & Administration

Initial Dose

5-10mg once daily for schizophrenia; 15mg once daily for acute bipolar mania (monotherapy)

Maintenance Dose

10-20mg once daily

Maximum Dose

20 mg per day.

Children's Dosage

Adolescents 13-17 years (schizophrenia and bipolar mania): Initial 2.5mg once daily, target 10mg/day, Max 20mg/day. Use with caution; greater weight gain and metabolic effects observed in adolescents.

Dose Adjustment Notes

Consider a lower starting dose (e.g., 5 mg once daily) in elderly/frail patients and/or hepatic impairment; titrate based on response/tolerability. Smoking induces CYP1A2 and can lower olanzapine exposure-dose may need adjustment if smoking status changes; strong CYP1A2 inhibitors (e.g., fluvoxamine, ciprofloxacin) may require dose reduction.

Side Effects

Common Side Effects

Weight gain, increased appetite, somnolence, dizziness, dry mouth, constipation, orthostatic hypotension; metabolic effects (hyperglycemia/diabetes risk, dyslipidemia); possible prolactin increase (usually less than many other antipsychotics).

Safety & Warnings

Contraindications

Contraindication: known hypersensitivity to olanzapine or any excipients.

Warnings & Precautions

Warnings/precautions: not approved for dementia-related psychosis (↑ mortality); metabolic monitoring (weight/BMI, glucose/A1c, lipids); somnolence and CNS depression; orthostatic hypotension/bradycardia risk (caution in CV disease/dehydration/antihypertensives); NMS and tardive dyskinesia; seizure risk; anticholinergic effects (caution in BPH, ileus, narrow-angle glaucoma); hepatic effects (monitor LFTs); leukopenia/neutropenia; DRESS; counsel on smoking changes affecting levels.

Age Restriction

Not approved for children <13 years (schizophrenia) and <10 years (bipolar I mania); safety/efficacy not established below these ages.

Drug Interactions

Interaction Severity

MAJOR: Fluvoxamine and other strong CYP1A2 inhibitors (e.g., ciprofloxacin) increase olanzapine levels; CNS depressants/alcohol increase sedation/impairment. MODERATE: Smoking and CYP1A2 inducers (e.g., carbamazepine, rifampin) decrease olanzapine levels; antihypertensives increase orthostatic hypotension risk; dopamine agonists/levodopa may have pharmacodynamic antagonism. MINOR: Antacids have minimal clinically relevant effect.

Food Interaction

No restriction.

Special Populations

Pregnancy

Consult Doctor

Children

Adolescents 13-17 years (schizophrenia and bipolar mania): Initial 2.5mg once daily, target 10mg/day, Max 20mg/day. Use with caution; greater weight gain and metabolic effects observed in adolescents.

Elderly

Start at 5mg once daily; titrate slowly; monitor for orthostatic hypotension, sedation, and metabolic effects. Not recommended for dementia-related psychosis.

Liver Impairment

Hepatic impairment: No dosage adjustment required; use with caution due to potential increase in aminotransferase levels

Storage & Patient Advice

Overdose

Symptoms: somnolence/sedation, tachycardia, agitation, dysarthria, anticholinergic effects, extrapyramidal symptoms, hypotension, respiratory depression/aspiration, seizures, coma, possible QT prolongation/arrhythmias; Management: emergency care with airway/ventilation support, cardiac/ECG monitoring, supportive treatment, consider activated charcoal if early; no specific antidote; avoid epinephrine for hypotension (use norepinephrine/phenylephrine).

Patient Counseling

Take once daily as prescribed (often evening if sedating); avoid alcohol and use caution driving until effects are known; rise slowly to reduce dizziness/orthostasis; do not stop abruptly without prescriber advice; monitor and manage weight/diet/activity and attend scheduled checks for glucose/lipids/BP; report symptoms of hyperglycemia (excess thirst/urination), severe rash, fever/rigidity/confusion (possible NMS), or abnormal involuntary movements; inform clinician about smoking changes and new medicines (especially fluvoxamine/ciprofloxacin/carbamazepine).

Monitoring Requirements

Baseline and periodic: weight/BMI and waist circumference, blood pressure, fasting glucose or HbA1c, fasting lipid panel; assess for extrapyramidal symptoms/tardive dyskinesia and sedation/orthostasis. Consider LFTs and CBC when clinically indicated (e.g., symptoms, comorbidities, or concomitant risks).

Pharmacology

Mechanism of Action

Atypical antipsychotic with antagonism at dopamine (primarily D2) and serotonin (notably 5-HT2A/5-HT2C) receptors, with additional affinity for histamine H1, muscarinic, and alpha-1 adrenergic receptors.

Duration of Effect

Approximately 24 hours (supports once-daily dosing); clinical symptom control is maintained with daily dosing and may persist beyond 24 hours due to a long elimination half-life.

Half-Life

Approximately 30 hours on average (range about 21-54 hours).

Bioavailability

Approximately 60% (oral), food does not affect absorption

Metabolism

Extensive hepatic metabolism mainly via direct glucuronidation (UGT1A4) and CYP1A2-mediated oxidation; minor contribution from CYP2D6 (and other CYPs to a lesser extent).

Excretion

Primarily as metabolites: ~57% in urine and ~30% in feces.

Product Information

Available Dosage Forms

For PREXAL specifically: Film-coated tablet (oral). In general for olanzapine: film-coated tablets, orally disintegrating tablets, short-acting IM injection, and long-acting IM depot injection (olanzapine pamoate).

Composition per Dose

Each film-coated tablet: Olanzapine 10mg

Generic Availability

Yes

OTC Alternatives

No OTC alternative.

Psych Class

Antipsychotic-Atypical

Controlled Substance

No

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