Therapeutic drug levels

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Therapeutic drug monitoring

Following are some of the drugs that are commonly checked, followed by the normal target levels:

• Acetaminophen: varies with use
• Amikacin: 15 to 25 mcg/mL
• Aminophylline: 10 to 20 mcg/mL
• Amitriptyline: 120 to 150 ng/mL
• Carbamazepine: 5 to 12 mcg/mL
• Chloramphenicol: 10 to 20 mcg/mL
• Desipramine: 150 to 300 ng/mL
• Digoxin: 0.8 to 2.0 ng/mL
• Disopyramide: 2 to 5 mcg/mL
• Ethosuximide: 40 to 100 mcg/mL
• Flecainide: 0.2 to 1.0 mcg/mL
• Gentamicin: 5 to 10 mcg/mL
• Imipramine: 150 to 300 ng/mL
• Kanamycin: 20 to 25 mcg/mL
• Lidocaine: 1.5 to 5.0 mcg/mL
• Lithium: 0.8 to 1.2 mEq/L
• Methotrexate: greater than 0.01 mcmol
• Nortriptyline: 50 to 150 ng/mL
• Phenobarbital: 10 to 30 mcg/mL
• Phenytoin: 10 to 20 mcg/mL
• Primidone: 5 to 12 mcg/mL
• Procainamide: 4 to 10 mcg/mL
• Propranolol: 50 to 100 ng/mL
• Quinidine: 2 to 5 mcg/mL
• Salicylate: 100 to 250 mcg/mL
• Theophylline: 10 to 20 mcg/mL
• Tobramycin: 5 to 10 mcg/mL
• Valproic acid: 50 to 100 mcg/mL

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Note:

• mcg/mL = microgram per milliliter
• ng/mL = nanogram per milliliter
• mEq/L = milliequivalents per liter
• mcmol = micromole

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

Values outside the target range may be due to minor fluctuations or may be a sign that you need to adjust the dose of the medicine. A dose may need to be skipped if the value measured exceeds the following levels.

Following are toxic levels for some of the drugs that are commonly checked:

• Acetaminophen: greater than 250 mcg/mL
• Amikacin: greater than 25 mcg/mL
• Aminophylline: greater than 20 mcg/mL
• Amitriptyline: greater than 500 ng/mL
• Carbamazepine: greater than 12 mcg/mL
• Chloramphenicol: greater than 25 mcg/mL
• Desipramine: greater than 500 ng/mL
• Digoxin: greater than 2.4 ng/mL
• Disopyramide: greater than 5 mcg/mL
• Ethosuximide: greater than 100 mcg/mL
• Flecainide: greater than 1.0 mcg/mL
• Gentamicin: greater than 12 mcg/mL
• Imipramine: greater than 500 ng/mL
• Kanamycin: greater than 35 mcg/mL
• Lidocaine: greater than 5 mcg/mL
• Lithium: greater than 2.0 mEq/L
• Methotrexate: greater than 10 mcmol over 24-hours
• Nortriptyline: greater than 500 ng/mL
• Phenobarbital: greater than 40 mcg/mL
• Phenytoin: greater than 30 mcg/mL
• Primidone: greater than 15 mcg/mL
• Procainamide: greater than 16 mcg/mL
• Propranolol: greater than 150 ng/mL
• Quinidine: greater than 10 mcg/mL
• Salicylate: greater than 300 mcg/mL
• Theophylline: greater than 20 mcg/mL
• Yobramycin: greater than 12 mcg/mL
• Valproic acid: greater than 100 mcg/mL

Review Date: 08/24/2009
Reviewed By: Frank A. Greco, M.D., Ph.D., Director, Biophysical Laboratory, The Lahey Clinic, Burlington, MA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).