Laboratory: Clinical Biochemistry
Test Name:
Test Code: MIS6
Clinical Information:
Test Indications: Amitriptyline is a tricyclic antidepressant that is metabolized to nortriptyline with similar pharmacologic activity as parent drug. The relative blood levels of amitriptyline and nortriptyline are highly variable among patients.
Recommendations:  Both amitriptyline and nortriptyline can cause major cardiac toxicity when the concentration of both compounds together is above 1.8 µmol/L. Cardiotoxicity is characterized by QRS widening, which leads to ventricular tachycardia and asystole.
Patient Preparation Instructions:  Therapeutic ranges should be determined in specimens drawn at trough immediately before next dose. Collect blood approximately 10 hours after last dose.
Collection Devices:
Do not use separator gel.
Specimen Required:

Plasma: 2.0 mL

Serum collected without gel is also acceptable.
Serum: 2.0 mL
Reference Values:
In-Common Laboratories Reference Values
Within 10 Days
See Also:
More Information:
Specimens that are obtained from gel tubes are not acceptable and will be rejected, as the gel absorbs the drugs and will lead to falsely decreased concentrations. Separate plasma or serum as soon as possible and no longer than 2 hours from time of collection and freeze.  Send frozen specimens to In-Common Laboratories (Test ID: AMIT/NORT).