Clozapine Plasma Concentration Calculator and Interpreter

MakThis educational tool estimates steady‑state (at least 5-7 days of consistent dosing) 12-hour trough concentrations (ng/mL) from published nomograms and typical interaction effects. Real patients can vary substantially (~±30%) due to sampling time, adherence, labs, and biology; confirm with therapeutic drug monitoring and clinical judgment.

Instructions for Proper Use

1. Maintain a consistent dose for at least 5-7 days. 
2. Enter the patient’s total dose, sex, age, weight in kg, smoking status, presence of valproate and inhibitors or inducers.
3. The calculator can give you a target daily dosage based on your target blood level (using the plot).
4. Make your dose adjustment then wait another 5-7 days and obtain a new blood level.
5. Enter the results of the ACTUAL blood level at the bottom of the calculator and receive feedback as to the discrepancy between the theoretical value and the actual value.
6. Click “copy summary” to copy the data and summary into the medical record.

The calculator was developed by Bruce Bassi MD, an inpatient and outpatient psychiatrist who regularly uses clozapine in his practice. The calculator was created with the use of AI and the references cited below. You are welcome to submit feedback.