Table 5.
Therapeutic drug monitoring (TDM)-informed decision-making algorithm for clozapine-treated patientsa [104]
| Clozapine levela | Response | Tolerability | Action |
|---|---|---|---|
| Subtherapeutic (< 350 ng/mL) | Insufficient | Intolerable | Increase dose slowly to reference range and treat side effects if possible |
| Insufficient | Tolerable | Increase dose to reference range | |
| Sufficient | Intolerable | Consider decreasing dose | |
| Sufficient | Tolerable | No changes needed, continue standard side-effect monitoring | |
| Within reference range (350–600 ng/mL) | Insufficient | Intolerable | Treat side effects and increase dose slowly remaining in the reference range, if tolerated |
| Insufficient | Tolerable | Increase dose slowly remaining in the reference range, if possible | |
| Sufficient | Intolerable | If tolerability does not improve, decrease dose, monitor to remain in the reference range, if possible | |
| Sufficient | Tolerable | Continue to monitor | |
| Supratherapeutic (> 600 ng/mL) | Insufficient | Intolerable | Consider decreasing dose, monitor. Consider prophylactic anticonvulsant |
| Insufficient | Tolerable | Consider cautious dose increase or augmentation. Consider prophylactic anticonvulsant in both cases | |
| Sufficient | Intolerable | Decrease dose slowly, monitor to remain in the reference range, if possible | |
| Sufficient | Tolerable | Continue to monitor concentrations. Be vigilant for tolerability issues and consider prophylactic anticonvulsant |
aRefers to clozapine only, not clozapine plus norclozapine
Adapted by permission from reference [104]