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Urine drug testing is an essential component of monitoring patients who are receiving long-term opioid therapy, and it has been suggested for patients receiving long-term benzodiazepine or stimulant therapy. Family physicians should be familiar with the characteristics and capabilities of screening and confirmatory drug tests.
Immunoassays are used for initial screening and can give false-positive and false-negative. All are considered presumptive until confirmatory testing is performed. False-positive have ificant implications for a patient's pain treatment plan, and false-negative can be a missed opportunity to detect misuse.
Immunoassays are qualitative tests used for initial screening of urine samples. They can give false-positive and false-negativeso all are considered presumptive until confirmatory testing is performed. Immunoassays for opioids may not detect commonly prescribed semisynthetic and synthetic opioids such as methadone and fentanyl; similarly, immunoassays for benzodiazepines may not detect alprazolam or clonazepam.
Immunoassays can cross-react with other medications and give false-positivewhich have important implications for a patient's pain treatment plan. False-negative can cause missed opportunities to detect misuse. Urine samples can be adulterated with other substances to mask positive on urine drug testing.
Family physicians must be familiar with these substances, the methods to detect them, and their effects on urine drug testing. Urine drug testing is an important part of managing long-term opioid therapy. With the recent increase in deaths caused by opioid overdoses, several federal and state regulations have been enacted that recommend or require urine drug testing in patients receiving long-term opioid therapy. Similar guidance has been suggested for patients receiving long-term benzodiazepine or stimulant therapy.
The purpose of urine drug testing is to monitor compliance with prescribed therapy and detect the use of nonprescribed and illicit substances, especially heroin and nonprescribed opioids and benzodiazepines, all of which can increase the risk of a fatal overdose. Several federal and state regulations have been enacted that recommend or require urine drug testing in patients receiving long-term opioid therapy. Similar guidance may apply to patients receiving long-term benzodiazepine or stimulant therapy. Ingestion of food containing poppy seeds will not cause a positive urine drug test result.
Similarly, passive inhalation of marijuana smoke is unlikely to cause a positive tetrahydrocannabinol urine test result. Enlarge Print. Urine drug testing Urine drug test table be used to monitor compliance with prescribed therapy and detect the use of nonprescribed and illicit substances, especially opioids, benzodiazepines, and heroin. Immunoassays are subject to false-positive and false-negative. All positive and any unexpected negative must be verified by confirmatory testing. Casual dietary ingestion of poppy seeds does not cause a positive result for opioids on urine drug testing.
Casual exposure to cannabis smoke does not cause a positive result on urine drug testing. A positive urine drug test result has ificant implications for a patient's pain treatment plan, as well as his or her personal and professional life. Many controlled substance treatment agreements specify that pain medications will be tapered off or stopped if a test result is positive.
Some state regulatory agencies require consultation with a pain management subspecialist if misuse is suspected 4 ; therefore, it is imperative that family physicians know how to order urine drug tests and interpret.
Family physicians cannot rely on urine drug testing alone to determine adherence to therapy, nor can testing reliably detect intermittent use of nonprescribed substances. Because there are no typical behaviors that predict misuse or diversion, monitoring of patients receiving long-term opioid therapy should include a focused history using validated tools e.
Before ordering a urine drug test, the physician must note when the patient last took a prescription medication to determine the likelihood of a positive test resultwhether any other medications were taken concurrently that might cross-react with the assayand whether any nonprescribed or illicit substances were used in the event of an unexpected positive result. The physician must also Urine drug test table aware of which substances are most commonly misused in the community.
Guidelines from the American Pain Society 5 and the Centers for Disease Control and Prevention 1 on the use of long-term opioid therapy for chronic noncancer pain recommend periodic urine drug testing for adherence to treatment, but the frequency is left to the individual physician. More frequent testing is required for patients at high risk of misuse and those with aberrant behaviors. Interagency guideline on prescribing opioids for pain.
June Accessed August 18, Urine, serum, saliva, sweat, and hair can be tested for the presence of drugs. However, urine testing is most common because of ease of collection, adequate sensitivity and specificity to detect commonly used drugs, and a longer window of detection than serum. Urine drug testing can be performed in the office as a point-of-care test, or the sample can be sent to a reference laboratory for testing.
Testing may be performed for reasons other than monitoring opioid therapy, 8 such as drug rehabilitation, employment requirements e. Properly performed urine drug testing involves two steps: an initial screening test followed by confirmatory testing for substances with positive screening. Confirmatory testing is also needed in situations with an unexpected negative result as a means of distinguishing a false negative from a true negative.
The initial screening test is usually an immunoassay, a qualitative test that screens for the five major drug classes targeted by federal workplace testing programs: opioids, cannabinoids, cocaine, amphetamines, and phencyclidine. Immunoassays can be performed at the point of care, provide rapidand are relatively Urine drug test table. Positive and unexpected negative samples are then sent to a reference laboratory for confirmatory testing. Immunoassays can also be sent to a reference laboratory with instructions to run confirmatory tests. Specific immunoassays must be ordered for different substances; therefore, physicians should be familiar with the test used in their office and at the reference laboratory they routinely use.
The typical immunoassay can detect only nonsynthetic opioids morphine and codeine. The immunoassays used for workplace testing programs are useful for detecting illicit substances such as cannabis or cocaine, but they do not reliably detect synthetic or semisynthetic opioids e. Therefore, many laboratories require a specific order to test for semisynthetic and synthetic opioids and other drugs such as carisoprodol Soma.
Immunoassays that test for the presence of other common prescription drugs, such as benzodiazepines, are also available. Many benzodiazepine immunoassays reliably detect nordiazepam metabolite of diazepam [Valium]oxazepam, and temazepam Restorilbut not alprazolam Xanaxlorazepam Ativanor clonazepam Klonopin. Furthermore, if benzodiazepine use is suspected, the sample must be sent for additional testing despite a negative initial screening result.
Most confirmatory tests use gas or high-performance liquid chromatography to separate various drugs, and mass spectrometry to detect them. These methods have a much lower threshold for detection and are able to accurately distinguish individual drugs and metabolites. Because of cost constraints, it is not practical to test each sample for every possible drug. The physician should be aware of which tests to order if nonadherence or substance misuse is suspected. The initial test should include the prescribed drug, amphetamines, opioids, cocaine, benzodiazepines, oxycodone, barbiturates, methadone, fentanyl, and marijuana.
Amphetamine, methamphetamine, methylenedioxyamphetamine, methylenedioxymethamphetamine. Alpha-hydroxyalprazolam, 7-aminoclonazepam, oxazepam. Noroxycodone, noroxymorphone, oxycodone, oxymorphone. Noroxymorphone, oxymorphone. Information from references 11 through Recently, several synthetic cannabinoids e.
If the patient's symptoms suggest ingestion of these drugs, urine and blood samples should be sent to laboratories that are capable of detecting them. Many drugs are rapidly metabolized into active or inactive metabolites. Drug testing is dependent on detecting these metabolites.
Opioids and benzodiazepines include multiple drugs with overlapping metabolic pathways, which can make interpretation of screening difficult eFigure Urine drug test table and eFigure B. Thus, the presence of morphine in a sample could indicate morphine, codeine, or heroin use, or any combination of these.
Similarly, the presence of hydromorphone Dilaudid could indicate hydromorphone, hydrocodone, or morphine use. Unexpected urine drug testing in a hospice patient on high-dose morphine therapy. Clin Chem. Rational use and interpretation of urine drug testing in chronic opioid therapy. Ann Clin Lab Sci. Identification of urinary benzodiazepines and their metabolites: comparison of automated HPLC and GC-MS after immunoassay screening of clinical specimens.
J Anal Toxicol. False-positive can occur from cross-reactivity of commonly used medications with the assay. This a particular concern with immunoassays. Table 3 lists common medications that can cause false-positive on urine drug testing. True-negative occur when a patient is not taking the medication as prescribed and there is no drug present in the urine sample, or when the drug is metabolized so rapidly that the metabolites are eliminated before they can be detected. False-negative occur when a drug or metabolite is present at such low levels that it is not detected.
Confirmatory testing is essential to distinguish a true negative from a false negative. Contaminants can also interfere with the immunoassay's ability to detect the presence of drugs. Amantadine, benzphetamine Regimexbupropion Wellbutrinchlorpromazine, clobenzorex not available in the United Statesdesipramine, dextroamphetamine, ephedrine Akovazfenproporex not available in the United Statesisometheptene component of Prodrinlabetalol, levomethamphetamine active ingredient in some over-the-counter nasal decongestant inhalersmethamphetamine, 3,4-methylene-dioxymethamphetamine MDMAmethylphenidate Ritalinphentermine Adipex-Pphenylephrine, promethazine, pseudoephedrine, ranitidine Zantacselegiline Eldeprylthioridazine, trazodone, trimethobenzamide Tigantrimipramine Surmontil.
Dronabinol Marinolefavirenz Sustivahemp-containing foods, proton pump inhibitors, tolmetin and other nonsteroidal anti-inflammatory drugs. Dextromethorphan, diphenhydramine Benadryldoxylamine, ibuprofen, ketamine Ketalarmeperidine Demerolthioridazine, tramadol, venlafaxine. Common interferences in drug testing. Clin Lab Med. The use of heroin with concurrent prescription opioids is also a cause for concern. Although both substances will give a positive result for opioids, the presence of 6-monoacetylmorphine indicates heroin use. This metabolite has a short half-life, however, with a window of detection in urine of approximately Urine drug test table to eight hours.
Acetylatedthebainemetabolite glucuronide is a metabolite of thebaine, which is found in street heroin; it has been proposed as a new marker to differentiate morphine and codeine ingestion from heroin use. Urine samples are sometimes contaminated deliberately by ingestion or addition of a foreign substance to prevent detection of illicit drugs. Common methods of tampering include dilution with water, addition of extraneous substances, or substitution of samples.
Table 4 lists commercially available agents marketed to help disguise the presence of illicit drugs in urine samples. Several commercially available point-of-care systems check for the presence of adulterants in addition to the substances being tested for.
The practice known as shaving can also confound drug test : a patient who is not taking the prescribed drug will add a small amount of the drug directly to the urine specimen to avoid having a negative test result.Urine drug test table
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