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The effect of clozapine on adverse incidents in a low-secure challenging behaviour unit

  • M Dominic Beer (a1), Al Aditya Khan (a2) and Kalaanithi Ratnajothy (a3)


Background: Previous studies have shown that as well as being an effective antipsychotic, clozapine reduced aggressive and violent incidents. Most of the studies measured the length of time the patients were on clozapine, or the dose of the clozapine when the effectiveness was evaluated.

Method: A retrospective audit was designed to see the effectiveness of clozapine in reducing incidents in a low-secure challenging behaviour unit. The number of incidents was calculated pre and post the date when clozapine serum level reached the therapeutic level of 0.35μg/l. Then, the number of incidents per month (incidents/month ratio) before and after reaching the therapeutic level was calculated.

Results: The number of incidents per month was reduced by over 75%. Before serum clozapine level reached 0.35μg/l the number of incidents/month/patient was 1.22 and after reaching 0.35μg/l, it was 0.26 (p=0.004).

Conclusions: The use of clozapine reduced the number of adverse incidents by 75%. The monitoring of serum levels was found to be clinically useful.


Corresponding author

Correspondence to: Dr M.D. Beer, Bracton Centre, Oxleas NHS Trust, Bracton Lane, Dartford, Kent DA2 7AF, UK. E-mail:


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