Issues for surgery
Risk of withdrawal if omitted (see Further information).
Risk of relapse of schizophrenia or bipolar disorder if omitted.
Risk of QT-interval prolongation if continued (see Interactions with common anaesthetic agents and Interactions with other common medicines used in the perioperative period).
Advice in the perioperative period
Elective and emergency surgery
Continue.
For patients who may decide to quit smoking during the perioperative period see Further information.
Post-operative advice
If a long Nil by Mouth (NBM) period is anticipated, or if there are concerns regarding enteral absorption, advice on alternative preparations/routes should be sought from a psychiatrist.
Patients receiving depot antipsychotic preparations
If a patient’s usual depot antipsychotic intramuscular injection is due whilst an inpatient ensure correct product is prescribed, it is administered by a healthcare professional who is aware of the correct injection technique (including use of z-track technique) and rotate injection site.
Interactions with common anaesthetic agents
Central Nervous System (CNS) depression
Also see Interactions with other common medicines used in the perioperative period.
Atypical antipsychotics have CNS depressant effects which may be additive with other medicines that also have CNS depressant effects such as:
- benzodiazepines
- inhalational anaesthetics and intravenous anaesthetics
- local anaesthetics
- opioids
Consult British National Formulary for available drugs in each class.
Hypotension
Olanzapine can increase the risk of hypotension when used concomitantly with inhalational and intravenous anaesthetics.
QT-Interval prolongation
Also see Interactions with other common medicines used in the perioperative period.
Amisulpride is known to cause QT-interval prolongation. Co-administration with other medicines known to prolong the QT-interval must be based on careful assessment of the potential risks and benefits for each patient.
Anaesthetic agents that may be used in the perioperative period that are known to, or predicted to, prolong the QT-interval include:
- desflurane, isoflurane, sevoflurane*
- thiopental (theoretical)**
*monitor ECG if concurrent use unavoidable; if risk factors for QT-prolongation are also present (increasing age, female sex, cardiac disease, and some metabolic disturbances e.g. hypokalaemia) use greater caution.
**monitor ECG with concurrent use if risk factors for QT-prolongation are also present (increasing age, female sex, cardiac disease, and some metabolic disturbances e.g. hypokalaemia).
Interactions with other common medicines used in the perioperative period
CNS Depression
Also see Interactions with common anaesthetic agents for information on opioids.
Olanzapine has CNS depressant effects which may be additive with antiemetics that also have CNS depressant effects such as cyclizine, droperidol and prochlorperazine.
Hypotension
Olanzapine can increase the risk of hypotension when used concomitantly with droperidol and prochlorperazine.
QT-interval prolongation
Co-administration of olanzapine with medicines known to prolong the QT-interval must be based on a careful assessment of the potential risks and benefits for each patient since the risk of torsade de pointes may increase.
Medicines that may be used in the perioperative period that are known to prolong the QT-interval include:
- ciprofloxacin*
- clarithromycin*
- domperidone - avoid
- droperidol*
- erythromycin – particularly intravenous*
- granisetron*
- haloperidol**
- loperamide*
- ondansetron*
*monitor ECG with concurrent use if risk factors for QT-interval prolongation also present (increasing age, female sex, cardiac disease, and some metabolic disturbances e.g. hypokalaemia).
*monitor ECG if concurrent use unavoidable; if risk factors for QT-prolongation are also present (increasing age, female sex, cardiac disease, and some metabolic disturbances e.g. hypokalaemia) use greater caution.
Antimicrobials
Also see QT-interval prolongation above.
Ciprofloxacin
Ciprofloxacin is predicted to increase the exposure to olanzapine. Monitor for adverse effects of olanzapine.
Myelosuppression
Concomitant use of olanzapine with the following can increase the risk of myelosuppression:
- co-trimoxazole
- linezolid
- trimethoprim
Whilst single surgical prophylactic doses should not pose a problem, monitor for side effects and consider reducing atypical antipsychotic dose if a prolonged course of clarithromycin or ciprofloxacin is required and monitor full blood count if a prolonged course of myelosuppressive medication is required.
Further information
Withdrawal
Abrupt withdrawal of olanzapine may result in symptoms including sweating, insomnia, tremor, anxiety, nausea and vomiting.
Smoking cessation
Tobacco is known to induce CYP1A2 resulting in reduced olanzapine plasma concentrations in smokers; this is thought to have limited clinical consequences. If a patient taking olanzapine decides to quit smoking during the perioperative period, they should be advised to report any increase in side effects to the prescriber as dosage adjustments may be necessary. Smoking status is not expected to affect the metabolism of the other atypical antipsychotics covered in this monograph.
Venous thromboembolism (VTE)
Cases of VTE have been reported with antipsychotic drugs, although a causal relationship has not been established. Patients with schizophrenia often have acquired risk factors for VTE; identify any risk factors and consider if thromboprophylaxis is indicated post-operatively.
References
Baxter K, Preston CL (eds), Stockley’s Drug Interactions (online) London: Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 20th August 2019]
Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 20th August 2019]
Summary of Product Characteristics – Olanzapine 10mg Film-coated Tablets. Accord Healthcare Limited. Accessed via www.medicines.org.uk 20/08/2019 [date of revision of the text September 2017]
Summary of Product Characteristics – ZYPADHERA® (olanzapine pamoate monohydrate) 210 mg powder and solvent for prolonged release suspension for injection. Eli Lilly and Company Limited. Accessed via www.medicines.org.uk 20/08/2019 [date of revision of the text November 2018]