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Please see our Clinical Diagnostics Assays section and Point of Care Diagnostic Devices section to find manufacturers that sell these products
Today there are many assays that enable clinicians to assess the appropriate dosage of therapeutic drugs or to screen for the presence of drugs of abuse. Some of these products require laboratory support, but many simple test kits are suitable for point-of-care use by medical professionals or for home and workplace use.
Therapeutic Drug Monitoring (TDM)
Therapeutic drug monitoring assesses the serum level of a specific drug relative to its therapeutic range—the concentration range where the drug has been shown to be effective without causing toxic effects in most people. In the 1970s, pharmacologists demonstrated that monitoring blood levels of antiepileptic drugs led to improved clinical outcomes. Serial determination of blood levels guided dosage adjustment until optimal drug levels were achieved.
Today, TDM is standard medical practice for the management of many medical conditions where dose concentrations are not reliably predicted and where untoward effects are manifest if the drug blood level is not maintained within the therapeutic window. Among the many drug-specific tests available are those for antiepileptics such as phenobarbital, cardiac drugs such as digoxin, bronchodilators such as theophylline, antibiotics such as the aminoglycosides, immunosuppressants such as cyclosporine, psychiatric drugs such as lithium, anticancer drugs such as methotrexate, and protease inhibitors such as indinavir.
Drugs of Abuse Testing
Screening for drugs of abuse can differentiate between drug-induced and primary psychiatric conditions and can confirm that a patient is substance-free before undergoing medical procedures. Drug screening of pregnant women with a history of drug abuse may be useful for educating the mother and for guiding treatment of the newborn. Some employers require a drug screen as part of an employment or pre-employment physical. Nearly all workers in occupations such as law enforcement and transportation are subject to periodic, random, and postincident drug screening.
There are two major test methods for urine drug screening: the immunoassay and chromatography (gas chromatography/mass spectrometry [GC/MS] or high-performance liquid chromatography [HPLC]). Immunoassays are preferred for the initial screening. In larger laboratories, the tests are often performed on highly automated analyzers, which also perform other urine and blood chemistries. Assays are also available for several smaller batch-type chemistry analyzers. Radioimmunoassays can be used for large batches of samples.
A number of single-use devices incorporating immunoassays and designed to be used outside of the traditional laboratory have become available. These devices require FDA approval to be sold in the United States, and their use in nonmedical environments such as workplaces and halfway houses may be regulated by state laws. They are generally acceptable for use in the office practice environment. Some home-use drug testing kits are also being sold. These consist of an initial quick at-home test, which, when suggestive of the presence of drugs, requires the user to send a specimen to a laboratory for additional testing.
Several major clinical technology companies produce dozens of drug-specific assays for both therapeutic monitoring and assessment of the presence of drugs of abuse.
- Abbott Diagnostics (Abbott Park, IL) and Beckman Coulter. Inc. (Brea, CA) offer various diagnostic assays for therapeutic drug monitoring and for detecting abused drugs and drug toxicity in patients. The assays can be used with one or more of the companies’ laboratory analyzers, including Abbotts’ Architect and AxSYM systems and Beckman Coulter’s DxC systems.
- PerkinElmer (Waltham, MA) offers the PerkinElmer® Clarus® 600 GC/MS system for analysis of drugs of abuse in biological samples.
The Drug Abuse Screening Test for Home Use
The FDA has an informational web site* for consumers and health-care professionals who want information on drugs of abuse test kits. There is general information specific to drugs of abuse home-use tests and collection kits. In addition, there are links to decision summaries, brand name searches, and a database of tests that have been cleared for over-the-counter (OTC) use.
- Craig Medical Distribution, Inc. (Vista, CA) offers a variety of rapid (8-min) multidrug urine tests in the format of a test card employing lateral flow immunoassays. The company claims that its tests detect drugs at the standard sensitivity cutoff levels established by the National Institute for Drug Abuse (NIDA) and the World Health Organization. Its QuickSCREEN™ Pro Drug testing device is a five-panel lateral-flow immunoassay that has been approved by the FDA. The device tests for amphetamines, a cocaine metabolite, methamphetamines, and 11-nor-D 9 tetrahydrocannabinol-9-carboxylic acid at the cutoff concentrations based on the NIDA guidelines.
- Phamatech, Inc. (San Diego, CA) manufactures the At Home™ Drug Test, which the company claims is the first FDA-cleared OTC rapid drug test kit. The test consists of the urine collection cup and the rapid drug screening device, which is a lateral flow immunoassay for the detection of methamphetamines, amphetamines, marijuana, cocaine, and opiates in about 10 min. A “preliminary” test result indicates that the device reacted with something in the urine, and the sample must be sent to a Phamatech contract laboratory for confirmation testing. A negative result indicates that none of the target drugs were detected in the sample.
*Information can be found at http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/InVitroDiagnostics/DrugsofAbuseTests/default.htm
Please see our Clinical Diagnostics Assays section and Point of Care Diagnostic Devices section to find manufacturers that sell these products