Urine Drug Testing. Why drug test? Set the Standard!

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1 Urine Drug Testing Urine drug testing is a valuable tool for the physician when making treatment decisions. Patients and physicians benefit from safe and effective treatment of pain but there are always risks associated with prescribing opioids and other controlled substances. Accurate information about the patient s current prescribed and un-prescribed medications is essential to prescribe controlled substances responsibly. Understanding test methodologies helps in appropriate interpretation of results. However, inappropriate interpretation of results may adversely affect treatment decisions because there may be a misconception of whether the patient is compliant or non-compliant with prescribed and nonprescribed medications. Why drug test? Helps you make better treatment decisions Improves quality of patient care Minimizes misuse, abuse and diversion Reduces liability when prescribing narcotics May reduce morbidity and mortality Checks for patient compliance Identifies any illicit drugs or unauthorized drugs that might influence therapeutic decisions Set the Standard! Most patients who are compliant are comfortable submitting a specimen for drug testing. Some may feel you distrust them. However, educating the patient about why you are testing helps them understand the benefits. They need to understand they are not being singled out. Narcotics are dangerous and urine drug testing is an essential safe guard to protect patients.

2 Drug Testing Methods Liquid Chromatography/Tandem Mass Spectrometry (LC-MS/MS): This is the most definitive laboratory-based procedure that identifies and quantitates specific drugs and/or their metabolites. Our mass spectrometers are all triple quadrupole mass spectrometers. This is the best technology available for drug testing. LC-MS/MS technology is the most sensitive, selective, accurate and precise method for drug testing which specializes in high throughput multi-component analysis. Ultra High Performance Liquid Chromatography (UHPLC) is a separation technique to separate molecules of interest which yields very narrow peaks and correspondingly high resolution. The sample is prepared and carried through a separating column by a liquid mobile phase where the analytes are divided into unique bands based on their molecular properties. Molecules flow at high pressures through a column. This column contains carbon based material which has varying affinity for the drugs of interest and their metabolites. This is where the molecules of interest are separated so they can be individually identified. The analytes are then washed from the column and sent to the ionization probe. At the ionization probe, the target drugs or metabolites are converted to a charged or ionized state, then sent to a triple quadrupole mass spectrometer.

3 The triple quadrupole mass spectrometer is a mass analyzer consisting of three quadrupoles arranged in series. Each quadrupole (Q) contains four circular rods placed in parallel to which an oscillating electric field is applied. Q1 and Q3 are responsible for filtering sample ions according to their mass to charge (m/z) ratio. In Q1, selection of target compound ions, called precursor ions, or parent ions, takes place. Ion selectivity is sensitive to within less than 0.1 amu (atomic mass unit), allowing a high degree of precision. Between Q1 and Q3, Q2 serves as a collision cell. Here, precursor ions are accelerated by an electric field and are collided with a low pressure inert gas to produce lower molecular weight fragments. These fragments are called product ions. The product ions enter Q3 where selection of required product ions takes place. Then the ions move to the detector where they are counted and converted to an electrical signal in which they are recorded as chromatograms and spectra. The resulting mass spectrum is like an individual fingerprint of the drug being tested, providing a highly selective identification. The signal from the most abundant product ion is used to quantitate the drug by comparison to a multilevel reference standard calibration. Electrospray ionization aerosolizes and electrically charges drugs and metabolites as they elute from the liquid chromatograph (LC) Parent ions Q1 Q2 Q3 Q2 Collision Chamber fragments drug or metabolite Q3 permits only specific drug fragments LC/MS/M S Detector Advantages Highly sensitive and selective Indentifies the parent drug and/or it s metabolite(s) Quantifies the result Highly reliable and accurate Detects drugs that cannot be detected by immunoassay and POCT. (Examples: Fentanyl, Meperidine, Tramadol) Gold standard methodology

4 Immunoassay Testing: Immunoassay drug tests are designed to classify substances as either present (positive result) or absent (negative result) according to a predetermined cutoff threshold (value). Some instruments may give a semi-quantitative result. The assay uses specially designed antibodies to detect the presence of a drug or metabolite. The drug or metabolite in the sample competes with the labeled drug or metabolite to bind antibody, forming an antigen-antibody complex. The amount of enzyme-labeled antigen that binds with the antibody is inversely proportional to the amount of drug or metabolite in the urine sample. Advantages Simultaneous and rapid results Calibration and controls are used to verify quality and consistency of results Better sensitivity and specificity compared to POCT Point of Care Test (POCT): Single use immunoassay devices without the need for instrumentation are available. Immunochromatographic methods used produce color coded results. Most POCTs are based on competitive immunochemical reaction between a chemically labeled drug (drug-protein conjugate) and the drug or drug metabolites which may be present in the urine sample for the limited antibody binding sites. Advantages Simultaneous and rapid results Portable Easy to use, requiring little training CLIA waived test, no lab director is required

5 Factors that determine results of drug testing: Sensitivity - is the ability of the test to detect a drug or class of drugs proportion of actual positives which are correctly identified. Sensitivity relates to the test's ability to identify a drug correctly. Specificity - measures the proportion of negatives which are correctly identified. It s the test's ability to react only with the drugs or metabolites being tested and to exclude other substances. A test with high specificity is rarely positive if a substance that is truly absent. Cross-Reactivity - is when a test cannot distinguish between the substance tested for and substance that may be chemically similar or even un-related. Variables Drug: time frame when drug was taken, dosage of drug, route of administration, half-life of drug, type of drug Patient: renal and hepatic function, disease states, metabolism, height, weight, body composition, body surface area, cardiac output, drug-drug interactions, drug-food interactions, age Urine: ph, adulteration, dilution Interpretation of Urine Drug Test Results Results of drug screens by point of care testing and immunoassay testing are not definitive results. Most immunoassay drug tests give a positive or negative result based on a predetermined cutoff concentration. Some screening methodologies can give you semi-quantitative results. Testing technology by immunoassay testing is constantly evolving and varied by manufacturer. Sensitivity and specificity of these screens also vary by manufacturer. Depending on these variables the drug test may or not be screen positive. Compounds or other drugs could also cross react with the assay causing an erroneous result. (Refer to cross reactivity chart.) Knowledge of these variables of tests utilized helps with interpretation of results. Therefore results for drug screening by immunoassay are considered presumptive. A presumptive positive test result for a specific drug indicates that the sample may contain the drug or metabolite tested. A presumptive negative result indicates that the sample may not contain a particular drug. Drug testing by immunoassay is considered a screen and not a definitive test. Confirmatory testing by liquid chromatography mass spectrometry would give a definitive result for drug testing.

6 False Positive Results Related to Immunoassay Testing The chart below references medications that could cause false positive results with immunoassay testing. Remember, medications that cross-react with screening tests vary with each manufacturer. Therefore it is important to understand the particular screen used when interpreting patient results. Drug/Drug Class Interfering Drug Drug/Drug Class Interfering Drug Amphetamine Brompheniramine Methadone Chlorpromazine and Methamphetamine Buproprion Clomipramine Chlorpromazine Diphenhydramine Diet pills (eg. Clobenzorex, Fenproporex) Doxylamine Ephedrine Ibuprofen Fluoxetine Quetiapine Nonprescription Nasal Inhaler (l-amphetamine) Thioridine Phentermine Verapamil Phenylephrine Opiates Dextromethorphan Phenylpropanolamine Diphenhydramine Promethazine Poppy Seeds Ranitidine Quietapine Selegliline (for Parkinson's Disease) Quinine Trazodone Quinolone Antibiotics (eg. Levofloxacin, Oflocacin) Tricyclic Antidrepressants Rifampin Barbiturates Ibuprofen Verapamil Naproxen PCP Detromethorphan Benzodiazepines Oxaprozin Tramadol Sertraline Venlafaxine Cannabinoids Antihistamines/Decongestants Doxylamine Antiviral Efavirenz Ibuprofen Dronabinol Impramine Ibuprofen Ketamine Ketoprofen Meperidine Naproxen Promethazine Proton Pump Inhibitors (eg. Pantoprazole)