Psychiatric medicines
Most psychiatric medicines are continued perioperatively to avoid relapse or withdrawal. Exceptions require a medicine-specific assessment and coordination with the prescriber.
Assessment depends on the exact antidepressant, mood stabiliser, antipsychotic, anxiolytic or stimulant, its interactions and the consequences of interruption.
Medicine-specific considerations
The following points identify issues for medicine-specific review. The SPAQI consensus, prescribing information and local policy provide the context for an individual plan.
- SSRIs and SNRIs: stopping them can cause discontinuation symptoms. They may add to bleeding risk, particularly with antiplatelet agents. Serotonin toxicity can occur with serotonergic drugs such as tramadol, pethidine and methylene blue.
- Tricyclic antidepressants: anticholinergic effects, QT prolongation and interactions with sympathomimetic agents.
- MAO inhibitors: potentially severe interactions with pethidine and indirect-acting sympathomimetics. Planning an MAOI-compatible anaesthetic is often preferred to abrupt withdrawal. Any interruption requires specialist planning.
- Lithium: this has a narrow therapeutic index. Toxicity risk increases with dehydration, renal impairment, NSAIDs and some antihypertensives. Fluid balance, renal function and levels may need attention around major surgery.
- Antipsychotics: QT prolongation, hypotension and relapse risk if stopped. Clozapine interruption has specific restarting requirements after a gap, and constipation or ileus warrants attention.
- Benzodiazepines: withdrawal risk with abrupt cessation in regular users.
- Stimulants: these have haemodynamic effects. Management varies between protocols.
Lithium, MAO inhibitors and other medicines with important perioperative interactions should not be managed using a blanket rule.
Practical application
- Early reconciliation of the exact agent, dose and timing helps identify medicines requiring a specific plan.
- Review of the planned anaesthetic and analgesic regimen can identify relevant interactions.
- Discussion with the prescribing psychiatrist may be helpful when interruption is contemplated.
- A baseline ECG may be appropriate when the patient or combined medicines raise concern about QT prolongation.
- Postoperative planning can include delirium risk and continuity of the usual treatment.
The drug-specific recommendations in the SPAQI consensus and local policy inform the individual plan. Documentation of any interruption and restart plan supports continuity of care.