Re-titration following a treatment break


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A patient is deemed to have had a clozapine treatment break if dosing has been interrupted for more than 48 hours.

If treatment has been missed for less than 48 hours this is not classed as a treatment break and dosing may resume without any adjustment.

Impact on full blood count monitoring

Clozapine monitoring service

Treatment break rules – change of blood test frequency

CPMS (Clozaril)

If there has been a break of more than 96 hours, revert to weekly blood tests for 6 weeks*

DMS (Denzapine)

If there has been a break of more than 72 hours, revert to weekly blood tests for 6 weeks*

ZTAS (Zaponex)

* After 6 weeks patients may resume their previous blood sampling schedule if authorised to do so by the monitoring service.

The clinical team must notify the clozapine patient monitoring service and Leverndale pharmacy of the treatment break as soon as possible, even if clozapine treatment has been resumed already.

Please note:

  • Patients must have a valid full blood count result in place before restarting clozapine
  • An ECG should be performed before resuming treatment if the treatment break exceeds 72 hours

Dosing information

Patients should recommence clozapine treatment starting from 12.5mg once or twice daily on day 1. The product information for clozapine suggests that re-titration to a previous dose may be achieved at a faster rate than initial titration, if it is safe to do so. The blank clozapine titration chart can be used for this purpose.

The following factors should be considered when deciding how quickly to build up the dose:

  • What dose was the patient on previously and for how long? The higher the dose, the longer re-titration will take.
  • Did the patient experience any issues during the original titration (e.g. postural hypotension, persistent tachycardia)?
  • What caused the treatment break (e.g. intolerable dose-related side effects, physical illness)?
  • The setting in which re-titration will take place. Hospital re-titrations may allow faster dose escalation as more intense monitoring is possible. Patients may be discharged prior to the completion of their re-titration if their CMHT can support the necessary monitoring.

If in doubt use the standard clozapine titration chart . This takes the daily dose to 275mg by day 15 and further alterations can be made from there as appropriate.

Preventing treatment breaks

Provide regular patient education emphasising the need for reliable compliance with treatment.

As admission to an acute hospital is often a source of unintended treatment breaks, ensure clozapine warnings on EMIS are up to date so that clozapine use is identified on the Glasgow Mental Health Summary within Clinical Portal.

Last reviewed: 18 August 2020

Next review: 01 August 2023

Author(s): Clozapine review group

Version: 1

Approved By: PMG-MH

Reviewer Name(s): Lead Clinical Pharmacist, Clinical Effectiveness Pharmacist