Olanzapine

How it works

It antagonises multiple receptors, principally dopamine D2 and serotonin 5-HT2A, with additional histaminergic, muscarinic and adrenergic blockade contributing to both efficacy and its side-effect profile.

Prescribing in practice

• It carries a high risk of metabolic adverse effects including weight gain, dyslipidaemia and hyperglycaemia or new diabetes, requiring proactive metabolic monitoring.
• Sedation and postural hypotension are common, and it is associated with an increased risk of stroke and death when used for behavioural symptoms in elderly people with dementia.
• The long-acting injectable form can rarely cause a post-injection delirium/sedation syndrome needing prolonged post-dose observation.

Monitoring

Monitor weight, waist circumference, fasting glucose or HbA1c, lipids, blood pressure and prolactin-related symptoms at baseline and at regular intervals.

Counselling the patient

• Expect possible weight gain and increased appetite, and engage with diet and activity advice.
• Rise slowly from sitting or lying to reduce dizziness, and be cautious with alcohol and sedatives.
• Attend physical-health monitoring appointments for weight, glucose and lipids.

Evidence & guidelines

NICE includes olanzapine among first-line antipsychotic options for schizophrenia and bipolar disorder, with emphasis on monitoring its metabolic effects.