Clozapine – Risks in Community Pharmacy

Updated 24/11/2022

Requirements for supplying clozapine (Clozaril, Denzapine, Zaponex)

Pharmacists are reminded that the MHRA license for clozapine requires that the patient, the prescriber and the dispenser are all registered with an appropriate clozapine monitoring service.  Furthermore, each individual supply must first be authorised by the monitoring service before being made. Clozapine is a dopamine D1, dopamine D2, 5-HT2A, alpha1-adrenoceptor, and muscarinic-receptor antagonist that is licensed for use in schizophrenia only in patients that are unresponsive to, or intolerant of conventional antipsychotics and other atypical antipsychotics.  It carries a high risk (~2%) of blood dyscrasias and other potentially fatal side effects.  To mitigate that risk, the manufacturer provides a monitoring service as part of the product licensing arrangements.  A supply must not be made unless authorised by the monitoring service against satisfactory blood results. The brands of clozapine available in the UK and their corresponding monitoring service are shown below:

Brand Manufacturer Monitoring Service SPC
Clozaril Mylan Clozaril Connect View on EMC
Denzapine Britannia Pharmaceuticals Ltd DMS View on EMC
Zaponex Leyden Delta B.V. ZTAS View on EMC

The monitoring services are available 24 hours, 365 days a year.

In Lincolnshire, all clozapine is prescribed by the local mental health trust – Lincolnshire Partnership NHS Foundation Trust and dispensed under contract by Lincolnshire Co-op Pharmacy.

It should be rare, therefore, for any other pharmacy to be approached regarding making, or a querying a supply of clozapine.  However, there can occasionally be exceptional circumstances, including patients who present from out of the area.

  • In the first instance, if approached regarding a supply of clozapine, the pharmacist should refer the patient back to their regular, monitoring service registered pharmacy.
  • In the second instance, if the patient is out of area, first contact the pharmacist at the Lincolnshire Co-op Pharmacy Tel: 01522 889 562.
  • In the third instance, the pharmacist should seek advice from the patient’s clozapine monitoring service.

At all times the pharmacist will need to ensure they comply with licensing restrictions described above.

Please see the Lincolnshire Joint Formulary for further information, including a link to the MHRA safety update regarding Clozapine and the potentially fatal risk of intestinal obstruction, faecal impaction, and paralytic ileus. This will help you to support patients who may present to your pharmacy with potential signs of Clozapine toxicity that may not be immediately obvious.

Care is also advised when providing smoking cessation advice and products, to check if the patient takes any medications that would need close monitoring, of which Clozapine is an example.

Smoking and smoking cessation: clinically significant interactions with commonly used medicines – GOV.UK (

Further resources:

Lincolnshire Joint Formulary

British National Formulary monograph