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  • Dr Stella E. Okereke-Nwokeji

Therapeutic Drug Levels

Therapeutic drug levels are lab tests used to check the presence and amount of  a drug in the blood. It can also be used to monitor and adjust prescribed medications. Below are commonly checked medications with their normal levels. 

Digoxin (Lanoxin): 0.8-2.0ng/ml

Lithium (Eskalith): 0.8-1.5mEg/L

Carbamazepine (Tegretl):4-10mcg/ml

Gentamycin (Geramycin):5-10mcg/ml (peak); <2.0mcg/ml (valley)

Phenytoin (Dilantin):10-20mcg/dL

Tobramycin (Tobrex): 5-10mcg/mL (peak); 0.5-2.0mcg/mL (valley)

Phenobarbital 9Solfoton): 15-40mcg/dL

Valporic Acid 9Depakene): 50-100mcg/ml

Theophylline (Aminophylline): 10-20mcg/dL

Vancomycin (Vancocin); 20-40mcg/ml (peak); 5-15mcg/ml (trough)

Others include:

  • Acetaminophen: varies with use

  • Amikacin: 15 to 25 mcg/mL (25.62 to 42.70 micromol/L)

  • Aminophylline: 10 to 20 mcg/mL (55.50 to 111.00 micromol/L)

  • Amitriptyline: 120 to 150 ng/mL (432.60 to 540.75 nmol/L)

  • Cyclosporine: 100 to 400 ng/mL (83.20 to 332.80 nmol/L) (12 hours after dose)

  • Desipramine: 150 to 300 ng/mL (563.10 to 1126.20 nmol/L)

  • Disopyramide: 2 to 5 mcg/mL (5.89 to 14.73 micromol/L)

  • Ethosuximide: 40 to 100 mcg/mL (283.36 to 708.40 micromol/L)

  • Flecainide: 0.2 to 1.0 mcg/mL (0.5 to 2.4 micromol/L)

  • Imipramine: 150 to 300 ng/mL (534.90 to 1069.80 nmol/L)

  • Kanamycin: 20 to 25 mcg/mL (41.60 to 52.00 micromol/L)

  • Lidocaine: 1.5 to 5.0 mcg/mL (6.40 to 21.34 micromol/L)

  • Methotrexate: varies with use 

  • Nortriptyline: 50 to 150 ng/mL (189.85 to 569.55 nmol/L)

  • Primidone: 5 to 12 mcg/mL (22.91 to 54.98 micromol/L)

  • Procainamide: 4 to 10 mcg/mL (17.00 to 42.50 micomol/L)

  • Quinidine: 2 to 5 mcg/mL (6.16 to 15.41 micromol/L)

  • Salicylate: varies with use

  • Sirolimus: 4 to 20 ng/mL (4 to 22 nmol/L) (12 hours after dose; varies with use)

  • Tacrolimus: 5 to 15 ng/mL (4 to 25 nmol/L) (12 hours after dose)


Credit:npclinicians.com and medlineplus.gov