Off-licence use of clozapine: Lessons from an inner-city NHS trust - Comparison with other NHS Trusts

Clozapine remains the only licensed antipsychotic for individuals with treatment-resistant schizophrenia. Despite its proven effectiveness, clozapine continues to be significantly underutilised. This underuse is attributed to multiple barriers, including the requirement for lifelong haematological monitoring, adverse effects often leading to discontinuation and complex regulatory constraints. Off-licence prescribing offers a pragmatic approach to mitigating some of these challenges and improving access. To date, it remains unclear how this approach is used in clinical practice and how its use may vary across hospitals.

We analysed the Zaponex Treatment Access System (ZTAS) registries of four large NHS hospitals in November 2025. These trusts were chosen for comparison because of their ethnic diversity. Prevalence rates of off-licence prescribing were calculated as proportions within each hospital trust. Differences in prevalence based on clinical reason for off-licence use and ethnicity were explored descriptively.

On 1st November 2025, a total of 3115 patients were prescribed clozapine across four NHS Trusts. Of these, 751 (24%) received clozapine under off-licence conditions. The highest proportion of off-licence prescribing was observed at SLaM (48%; n = 612) followed by ELFT (12%; n = 79), with lower rates at SWLSTG (5%; n = 36) and NHT (5%; n = 24). SLaM had the greatest proportion of patients receiving extended three-monthly haematological monitoring (40%; n = 517), a key driver of off-licence use, while this practice was rare or absent in other Trusts. Black patients were disproportionately represented among those prescribed clozapine off-licence for reasons other than extended monitoring, with BEN monitoring being the most frequent reason.

Off-licence prescribing of clozapine offers a pragmatic and timely alternative to optimise its therapeutic benefits for individuals with severe, treatment-resistant psychiatric disorders, while regulatory changes are awaited. The higher rate of of-licence use in SLaM likely reflects a concentration of specialist expertise rather than a model that is immediately generalisable.