Healthcare professionals in non-specialist services managing patients prescribed clozapine should implement safe practice principles to prevent potential harms.

Patient harm

Patients prescribed clozapine may interact with all sectors within a system and clozapine use will impact clinical decisions made in settings that are different from where it is prescribed and supplied.  Therefore all healthcare professionals should be aware of the risks and how to manage these.

Patients prescribed clozapine who are being cared for by healthcare professionals who are unfamiliar with the clinical consideration for patients prescribed clozapine may lead to patient harm.

Failure to provide clinically appropriate monitoring, prevent omission of doses, identify potential interactions, or respond appropriately to adverse effects, can lead to serious harm.

System wide risks

Risks associated with clozapine are system wide.

Documentation and communication

Lack of awareness and documentation that a patient is prescribed clozapine has the potential for harm.

Unfamiliarity with clozapine may result in failure to recognise:

  • clozapine as a time critical medicine leading to inadvertent dose omissions or unintentional discontinuation of therapy
  • adverse effects or signs of toxicity, such as constipation or sore throat, leading to inappropriate management and lack of urgent referral
  • the impact of prescribing or deprescribing interacting medicines that may affect clozapine plasma levels
  • the impact of lifestyle changes (such as changes in smoking status or caffeine intake) on clozapine plasma levels
  • the impact of an acute infection on clozapine plasma levels
  • timely specialist mental health advice is needed when concerns are identified
  • annual physical health checks are needed

Failure to communicate the intended brand, dose and blood monitoring arrangements has led to patient harm.


Administration of clozapine is time critical. Failure to ensure that clozapine is available in a timely fashion can lead to dose omissions, subtherapeutic dosing or a need to re-titrate.

A patient’s clozapine supply should travel with them across care settings to ensure availability.  This is due to the restriction of supply to named pharmacy services only.

Failure to follow monitoring requirements may lead to a lack of clozapine supply, causing an interruption in treatment.

Sector specific risks

Use of clozapine is system wide, yet each sector has specific risk scenarios associated with known harms.  Awareness of these risks can support prioritisation of mitigation strategies.

Primary care

Risks in the primary care sector are generally related to documentation or clinical knowledge.

Lack of documentation in the medical records/Summary Care Record (SCR) that the patient is taking clozapine and not having this visible at the point of consultation and prescribing.

Failures in the communication at transfers of care can result in failure to recognise that an individual is prescribed clozapine.

Harms can also occur where individuals presenting with possible clozapine adverse effects or signs of toxicity are inappropriately referred to non-urgent review pathways for further management.

Community pharmacy

Lack of documentation on dispensing records or Medicines Administration Record (MAR) charts has led to failure in recognising an individual is on clozapine.

Lack of awareness may lead to inappropriate recommendations of non-prescription medications to treat clozapine-related toxicity or adverse effects that may require urgent referral, for example constipation or sore throat.

Harm may result from the inappropriate provision of advice related to smoking cessation due to lack of awareness of the effect on clozapine plasma levels.

Care homes

Known risks in care homes include failure to recognise:

  • an individual is prescribed clozapine due to lack of documentation on care plans and Medicines Administration Record (MAR) chart
  • clozapine is a time critical medicine
  • the impact of missed doses due to lack of availability/supply of clozapine/swallowing difficulties
  • clozapine toxicity or adverse effects, with appropriate management and referral
  • the need to monitor bowel movements to prevent severe constipation

Secondary Care

Known risks in the acute sector include failures to:

  • prescribe clozapine on admission due to a lack of awareness that the individual is taking clozapine
  • recognise clozapine is a time critical medicine
  • recognise toxicity or clozapine related adverse effects, with appropriate management and referral

A lack of knowledge of the following key events may result in unintended changes to clozapine plasma levels:

  • starting or stopping interacting medicines
  • a change in smoking status
  • presence of a severe infection


There are opportunities to minimise potential harm by addressing the risks present across the system.

Awareness and knowledge

Ensure every healthcare professional with the potential to interact with a patient prescribed clozapine are aware of the risks associated with it. Training and competency requirements should address these risks.

Ensure all healthcare professionals, and care navigation staff, are aware of the potential harms and risks associated with clozapine use, and understand the need to consider the clinical consideration for patients prescribed clozapine.

All staff should be aware of the need to escalate any concerns to senior colleagues or specialist clinicians.

Organisational policy

Define responsibilities in an organisational policy including prescribing, supply, administration, monitoring and acting on results, as appropriate.

Clarify processes for both within normal working and out of hours.  Details, including contact methods for external teams, and provision for accessing patients’ regular medication information, are pertinent.

Include the requirement to inform the specialist mental health team when there are any transfers of care.

Implement systems to enable prioritisation of patients with a mental health diagnosis during transfers of care, such as timely medicines reconciliation.

Identification of therapy

Review feasibility and utilise digital solutions where possible.

Review systems where medication therapy and care plans are documented to ensure clozapine is clearly identifiable. This is of particular importance for care settings where clozapine is not prescribed or supplied.

Clinical decision support software

Pop-up alerts can be configured when accessing patient records to support the identification of clozapine therapy and associated clinical considerations.

Inclusion of clozapine in relevant electronic lists on the patient medical record, even if prescribing and supply is on another system, allows for in-built interaction and clinical decision support to recognise clozapine therapy.

Inclusion of a clozapine ‘label’ in electronic prescribing systems and dispensing systems will support users to identify clozapine as a concurrent medicine, especially if prescribing and supply is documented on another system.

Summary Care Record

Clozapine should be entered onto the GP System as a ‘Repeat Medication prescribed elsewhere’, this will show on the Summary Care Record (SCR) until the medicine is discontinued. Adding a medicine as an ‘Acute Medication prescribed elsewhere’ will only show on the SCR for 12 months.

Be aware that if the GP practice has their system set to delete medication not issued after a fixed period of time the hospital issue-only medication will go into the ‘past drugs’ section.  NHS digital have information about how to add these medicines

A system should be in place to ensure that hospital issue-only medicines are removed or amended on practice systems only when notified by the specialist prescriber.


Ensure patients are coded and on the Severe Mental Illness (SMI) register to promote annual physical health checks.


Ensure clear documentation and communication at the point of prescribing and at all transfers of care.  This includes any changes made within specialist settings, which should be communicated to the GP.  Information should contain the following as a minimum:

  • prescriber name and mental health team
  • brand details and dose
  • blood monitoring frequency
  • responsibility for physical health monitoring
  • supplying pharmacy
  • emergency contact details for mental health team

Record smoking status and caffeine intake at every contact.

Care plans should also include identification of possible adverse effects and signs of toxicity that need immediate medical attention.

Ensure the patient/carer is involved where possible.

Use electronic solutions such as the discharge medicines service (DMS) and electronic prescribing systems where possible.

Ensure the results of the annual physical health checks are communicated to all healthcare teams involved in patient care.

Specialist advice

Close working relationships with local mental health services can support timely access to specialist support.  Provision of ‘in-reach’ specialist mental health pharmacy services from local mental health trusts to secondary care enables a point of contact for advice and queries.

Some acute hospitals will have a psychiatric liaison team who can offer support and advice.

Ensure all healthcare staff have an awareness of the referral process.

Contact Details

Ensure contact details for local mental health trusts, including the out of hours service, are on the ICB webpage and the local intranet.

Further information

Clinical consideration for patients prescribed clozapine

Clozapine use in adults with swallowing difficulties

Managing constipation in people taking clozapine

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