Therapeutic drug monitoring measures the serum level of a specific drug relative to its serum therapeutic rangethe concentration range where the drug has been shown to be efficacious without causing toxic effects in most people.
In the 1970s pharmacologists demonstrated improved clinical outcomes derived from monitoring blood levels of drugs that were administered to control epileptic seizures. The determination of blood levels guided dosage adjustment until optimal drug levels were achieved.
Today, therapeutic drug monitoring (TDM) is standard medical practice in the management of many medical conditions where the dose-concentration relationship is not reliably predicted and where untoward effects are manifest if blood level of the drug is not maintained within a therapeutic window.
Among the many drug-specific tests available are those for anticonvulsants, Digoxin, Theophylline, Lithium and tricyclic antidepressants. Abbott Laboratories, Abbott Park, Ill., like several other major clinical technology firms, produces literally dozens of drug-specific assays for both therapeutic monitoring and assessment of the presence of drugs of abuse. These products are designed to coordinate with one or more of the companys laboratory analyzers, including its Aerosrt, Architect, AxSYM and TDx systems.
Drugs of Abuse
Drugs of abuse screening can help differentiate symptoms in many diseases and can insure that a patient is substance-free before undergoing medical procedures. Drug screen ing of pregnant women with a history of drug abuse may be useful as an educational tool and help guide treatment of the newborn. Some employers require a drug screen as part of an employment or pre-employment physical. Nearly all workers in some occupations, such as law enforcement and transportation, are subject to periodic, random, and post-incident drug screening.
The most commonly used test method for screening urine for drugs of abuse is immunoassay. In larger laboratories, the tests are often performed on the highly automated analyzers, which also perform other urine and blood chemistries. Methods are also available for several smaller batch-type chemistry analyzers. Radioimmunoassay 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 non-medical environments such as workplaces and halfway houses for criminals 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 generally are not testing devices themselves, but are specimen containers which are to be filled and sent to a central laboratory, where the actual testing is done. The price of the kit includes the testing.
In the drugs of abuse category, several firms produce test kits that can be used in point of care settings to monitor drug free status or in the pre-employment setting to rule out illegal drug use.
A1 UA Test Kits from Transmetron, Salt Lake City, Utah, are based in a self-contained urinalysis drug test process that detects the presence of drug metabolites in urine within minutes. The kits cup contains detection strips designed to test for a particular drug at NIDA cut-off levels. It provides instant results using a technology similar to that fo und in home pregnancy tests. Through the patented delivery system, urine reacts with the reagents and antigens on the strip to produce a colorimetric reading indicating either positive or negative test results.
Craig Medical Distribution, Inc., Vista, Calif., produces the RapidCHECK 7 multi-drug screening test for the detection of seven drugs and drug metabolites simultaneously; THC (Marijuana), Cocaine and its metabolite, benzoylecgonine, Opiates, Oxycodone (Vicodin), Methamphetamines (including Ecstasy), Methadone, and Amphetamines (Phentermine etc.) in one simple test device. The company says that this test is also recommended for an all-inclusive scan when drug use is suspected but the specific target drug is unknown. Results are obtained within eight minutes and are 98 percent accurate.
Phamatech, Inc., San Diego, Calif., manufactures QuickScreen multi-panel dip cards that offer minimal exposure to the urine sample and selectivity for any combination of nine different drugs. The test card is dipped into the urine specimen and a built-in timer indicates availability of results. The slit-lid cover and a hinged leak-proof lid snap into place making the product, according to the company, the most secure collection container on the market. The specimen donors name can also be written directly on the device, and QuickScreen cards can be photocopied for easy tracking of on-site screening results.
Forefront Diagnostics, Inc., San Diego, Calif., produces the InstaCheck multi-drug test device that provides clear, reliable results simply and easily. Negative results can be determined in as few as three minutes; positive results require eight minutes. Aside from its speed, this product features a one-step device requiring no incubation period, specimen transfers, or washing steps and up to an 18-month shelf life at room temperature.
While the availability of these tests has satisfied a widespread demand, laboratory testing for drugs of ab use is a technically challenging procedure, even for medical professionals, and tests performed at home by untrained parents might have higher rates of error than professional tests with at least one study suggesting that false negative tests can be as high as 6-40 percent in a certified laboratory, depending on the drug detected.
All positive urine screening tests for drugs should be confirmed, especially if any medical, legal or employment consequences can result from the positive test. The accepted confirmatory test for all drugs is gas chromatography-mass spectrometry, often abbreviated GC-MS. GC-MS can identify the specific substance ingested by recognizing not only the molecular structure of the original compound, but also its pattern of metabolites.
Related medicine technology :
1. Monitoring Patient Glucose Levels: New Advances in software make it easier