Microsoft word - food and drug interactions with udt.doc

Pain Physician: March/April 2011; 14:123-143 spectrometry (LC/MS/MS) or high performance liquid samples showed that 75% of patients were unlikely chromatography (HPLC). Enzyme-mediated immuno- to be taking their medications in a manner consis- assay (EIA) is frequently used as the initial evaluation tent with their prescribed pain regimen (158). This for UDT, which can test for numerous drugs or drug evaluation showed that 38% of patients were found classes, and can determine if a class of substances is to have no detectable level of their prescribed medi- present or Fo
EI cAtsi odns
o intshtr P
at oe int-of-Car
cation, e Ur
a ug Tests:
adequate sensitivity but are not specific. They cannot ent, 27% had a drug level higher than expected, 15% equivocally identify a specific analyte and can result had a drug level lower than expected, and 11% had in false-negatives by missing compounds such as oxy- illicit drugs detected in the urine (158). Further, it has • Quinolone antibiotics (ex. levofloxacin, codone, methadone, and fentanyl (195,196). c they also fail to distinguish between diffe •r en D of the same class (e.g., opioids) and can produce to 50 μg /L increased efficiencies and sensitivities for false-positive results from cross-reactivity with other all immunoassays, with minor decreases in specific- substances (e.g., quinolone antibiotics or any com- ity (198). Consequently, the cutoff levels, which have pound with similar structural and chemical properties been reduced to 20 and 15, further increases true- to the original substance). Table 3 illustrates various drug cross-reactants. In addition, EIAs exhibit cross- To identify individual drugs and metabolites, lab- reactivity with other commonly available medications oratory testing is recommended. Thus, a urine screen that is positive for hydromorphone in a patient re- g is required when an ceiving hydrocodone does not reflect drug abuse, but immunoassay is initially used and provides • bo T igh rather the appropriate metabolite of hydrocodone. sensitivity and high specificity to reduce • Bupropi false-posi- on Similarly, since codeine is metabolized to morphine, a • Desipramines creen that is positive for morphine in a patient taking Multiple publications have shown not• onA h ne codeine would be expected (199). Historically, there rates of inappropriate drug use in the ch•r onRa n have been instances in which physicians who were population, but also have identified multi • s not familiar with opioid metabolism have wrongly ac- for confirmatory testing along with diff • pat ients of drug abuse (197). Table 4 illustrates cutoff levels. Further, metabolic variation • Vicks Vapor Inhaler metabolites of opioids (199,200). In addition, preva- suggested for confirmatory testing (197). • Oxaprozin (Daypro) lence of morphine metabolism to hydromorphone in spective analysis of screening for non-compliance, in chronic pain patients treated with morphine also has the data collected in almost a million patients, test been established (197). It is also essential to note that Drug Cross-Reactants
Poppy seeds, chlorpromazine, rifampin, dextromethorphan quinine Ephedrine, methylphenidate, trazodone, bupropion, desipramine, amantadine, ranitidine, Chlorpromazine, thioridazine, meperidine, dextromethorphan, diphenhydramine, doxylamine Gas chromatography should confirm all positives; screening detects a presence or absence, not the concentration. Drug tests are not quantitative.
Source: Manchikanti L, et al. Protocol for accuracy of point of care (POC) or in-office urine drug testing (Immunoassay) in chronic pain patients: A prospective analysis of immunoassay and liquid chromatography tandem mass spectometry (LC/MS/MS). Pain Physician 2010; 13:E1-E22 (49).

Source: http://www.srfmr.org/uploads/provider_resource/1332903340-84cd7af52852cea24/Food%20and%20Drug%20Interactions%20with%20UDT.pdf