Olanzapine
Mechanism :
Olanzapine is an antagonist with moderate affinity binding for serotonin 5HT3 and muscarinic M1-5, respectively. Olanzapine binds weakly to GABAA, BZD, and beta-adrenergic receptors.
Indication :
- Schizophrenia
- Mania
- Bipolar depression
- Stuttering
Contraindications :
Contraindicated in patients with a known hypersensitivity to the product. May exacerbate, possibly precipitate, diabetes mellitus, low white blood cell count or liver dysfunction. Caution in galactosemia and phenylketonuria due to excipients.
Dosing :
Schizophrenia, Mania:
13-17 years: 2.5-5 mg/day orally, initially, adjust by increasing or decreasing by 2.5-5 mg. Target dose: 10 mg/day; Max dose: 20 mg/day.
Bipolar depression:
10-17 years: 2.5 mg orally in the evening and
fluoxetine 20 mg orally, every evening initially, dosage adjustments if needed.
Stuttering:
<12 years: 1.25 mg orally at bedtime for one month, then 2.5 mg at bedtime.
>12 years: 2.5 mg orally, at bedtime for one month then 5 mg at bedtime.
Adverse Effect :
Commonly seen side effects include weight gain, hypertriglyceridemia, hypercholester-olemia, drowsiness. Less commonly seen are postural hypotension, xerostomia, insomnia, constipation, dyspepsia, hyperprolactinemia, hyperglycemia, accidental injury and peripheral edema. Blood dyscrasias, seizures, hyperglycemia, extra-pyramidal syndromes, neuroleptic malignant syndrome have been reported rarely.
Interaction :
Omeprazole and Rifampin: May cause an increase in olanzapine clearance.
Carbamazepine: Causes an increase in the clearance of olanzapine. This increase is likely due to the fact that carbamazepine is a potent inducer of CYP1A2 activity. Higher daily doses of carbamazepine may cause an even greater increase in olanzapine clearance.
Fluoxetine: Causes a small increase in the maximum concentration of olanzapine and a small decrease in olanzapine clearance.
Fluvoxamine: A CYP1A2 inhibitor, decreases the clearance of olanzapine.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | Initial dose 5 mg daily and titrate as necessary |
| 10-20 | Initial dose 5 mg daily and titrate as necessary |
| <10 | Initial dose 5 mg daily and titrate as necessary |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Not dialysed. Dose as in GFR<10 mL/min |
| HD | Not dialysed. Dose as in GFR<10 mL/min |
| HDF/High flux | Unknown dialysability. Dose as in GFR<10 mL/min |
| CAV/VVHD | Unknown dialysability. Dose as in GFR=10–20 mL/min |
Hepatic Dose :
4-6years: 0.65mg daily.
6-12y: 1.25mg-2.5mg daily, increasing weekly based on response.
Adolescent: 1.25-2.5mg daily, increasing weekly based on response target dose 5 mg/day.