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Therapeutic drug level are laboratory tests to look for the presence and the amount of specific drugs in the blood.
Alternative NamesTherapeutic drug monitoring
How the test is performedBlood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.
Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.
Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.
See also: Venipuncture
The sample is then taken to the laboratory, where it is checked for the particular drug specified by your health care provider.
How to prepare for the testSome drug level tests require preparation. Your health care provider will tell you how to prepare.
How the test will feelWhen the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performedWith most medications, you need a certain level of drug in your bloodstream to obtain the desired effect. Some medications are harmful if the level rises too high and do not work if the levels are too low.
Monitoring the amount of the drug found in your blood allows your health care provider to make sure the drug levels are within an effective range.
Drug level testing is especially important in people taking drugs such as:
- Procainamide or digoxin used to treat abnormal beating of the heart
- Dilantin or valproic acid used to treat seizures
- Gentamicin or amikacin, antibiotics used to treat infections
Testing may also be done to determine how well your body breaks down the drug ( metabolism), or how it interacts with other necessary drugs.
Normal ValuesFollowing 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
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.
What abnormal results meanValues 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
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Wiki User
∙ 13y ago
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∙ 12y agoTherapeutic drug level are laboratory tests to look for the presence and the amount of specific drugs in the blood.
Alternative NamesTherapeutic drug monitoring
How the test is performedA blood sample is needed. For information on how this is done, see:Venipuncture
How to prepare for the testSome drug level tests require preparation. Your health care provider will tell you how to prepare.
How the test will feelWhen the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performedWith most medications, you need a certain level of drug in your bloodstream to obtain the desired effect. Some medications are harmful if the level rises too high and do not work if the levels are too low.
Monitoring the amount of the drug found in your blood allows your health care provider to make sure the drug levels are within an effective range.
Drug level testing is especially important in people taking drugs such as:
- Procainamide or digoxin used to treat abnormal beating of the heart
- Dilantin or valproic acid used to treat seizures
- Gentamicin or amikacin, antibiotics used to treat infections
Testing may also be done to determine how well your body breaks down the drug ( metabolism), or how it interacts with other necessary drugs.
Normal ValuesFollowing 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
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.
The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.
What abnormal results meanValues 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
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Review Date: 05/12/2011
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.
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What is drug therapy monitoring?
Drug therapy monitoring, also known as Therapeutic Drug Monitoring (TDM), is a means of monitoring drug levels in the blood.
Why are blood levels checked when using medications?
In situations where a clear dose-response relationship exists for the drug in question, monitoring drug serum levels where there is a narrow therapeutic margin helps maintain the dose in a range where adequate therapeutic benefit is seen while avoiding toxic levels. Examples of this include Dilantin for seizures, and antibiotics like gentamicin or vancomycin.
What is meant by therapeutic study of drug?
Therapeutic study of a drug is scientific research to find out if the medication can be used to treat disease.
What can drug therapy monitoring confirm?
confirm a blood drug concentration level that is above or below the therapeutic range, or if the desired therapeutic effect of the drug is not as expected.
What are the 7 therapeutic uses for drug?
in pharmacology the seven therapeutic uses of drugs
What is therapeutic effect of a drug?
The therapeutic effect is otherwise known as the "desired effect". The effect we want the drug to do. In contrast to Adverse or undesired effect.
What is the definition of supratherapeutic?
Supratherapeutic means having a drug level in the body that is higher than the recommended or therapeutic range, which can increase the risk of adverse effects or toxicity.
When is trough therapeutic drug level drawn?
Blood specimens for drug monitoring can be taken at two different times, called peak and trough levels. Blood for peak level is collected at the drug's highest therapeutic concentration within the dosing period. For drugs given intravenously, the peak level is drawn 30 minutes after completion of the dose. For drugs given orally, this time varies with the drug because it is dependent upon the rates of absorption, distribution and elimination. For intravenous drugs, peak levels can be measured immediately following complete infusion. Trough levels (occasionally called residual levels) are measured just prior to administration of the next dose, and are the lowest concentration in the dosing interval. Too low a dose or too great a dose interval will produce a trough level that is below the therapeutic range, and too great a dose or too close a dose interval will show a peak level greater than the therapeutic range. Most therapeutic drugs have a narrow trough to peak difference, and therefore, only trough levels are needed to detect blood levels that are too low or too high. Peak levels are needed for some drugs, especially aminoglycoside antibiotics.
What is the purpose of a therapeutic drug?
The purpose of a therapeutic drug is to treat, manage, or cure a medical condition, illness, or disease. These drugs are designed to alleviate symptoms, improve quality of life, or restore normal bodily function in patients.
What does it mean by non-therapeutic Effects of Drug?
Non-therapeutic drug effects are those that don't treat the target condition. For instance, the stomach cramping caused by erythromycin is a non-therapeutic effect when erythromycin is used for infection; interestingly, it may be a therapeutic effect if erythromycin is used for gastroparesis.
What is tdms in Phlebotomy?
TDM stands for Therapeutic Drug Monitoring.
What is the therapeutic index of drugs?
The therapeutic index of drugs is the ratio between the amount of drug needed to kill 50% of the cells of the experimental animals and the dose needed for 50% of the cells to respond. The larger the therapeutic index, the safer the drug.
