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Drug of Abuse Tests
Neurology
| Question | Answer |
|---|---|
| EtOH: Always assume: | other drugs may be involved |
| Blood EtOH usu measured on: | whole blood (serum levels 12% higher than whole blood) |
| EtOH PK | clearance by zero-order kinetics (constant rate); half life: 18 mg/dL/hr |
| EtOh detection window | blood: 1.5-12 hr (urine an extra 1-2 hrs); urine assays less reliable |
| EtOH correlation: Partition Ratio: | Breath is 1; Urine is 1.3; Blood is 2100 (avg. range 1300:1 to 3100:1) |
| EtOH test methods | Alcohol dehydrogenase: all alcohols (quant); GLC: quant & qualitative |
| Chronic alcohol use: labs | macrocytosis; anemia (later); high AST, ALT, GGT, CDT |
| Substance abuse testing: | no universal requirement for informed consent; pt safety & tx comes first |
| DHHS guidelines for testing drugs: | Amphetamines, cannabinoids, cocaine, opiates & PCP; workplace cut-off levels may not be appropriate for clinical setting |
| Urine drug test methods | Immunoassay; GC-MS (HPLC) |
| Drug test: Immunoassay | fast; large-scale screening; false pos & req confirm by HPLC |
| Drug test: HPLC | accurate; time consuming; expensive |
| Opiates | Natl: heroin & hydrocodone; synthetic: meperidine & methadone (less detectable) |
| Horse tranquilizer: | PCP |
| Serum drug screen | for OD/EtOH; 1 mL min, green top tube; tests: Acetaminophen; Salicylate; Tricyclics; Ethanol |
| Drug with longest detection time: | Benzo or THC |
| Drugs with lowest/highest detection thresholds: | Lowest: THC; highest: amphetamine |
| Blood EtOH usually measured on: | whole blood (serum levels 12% higher than whole blood) |
| Chronic alcohol use: labs | macrocytosis; anemia (later); high AST, ALT, GGT, CDT |
| Urine drug test methods | Immunoassay; GC-MS (HPLC) |
| Drug test: Immunoassay | fast; large-scale screening; false pos & req confirm by HPLC |
| Drug test: HPLC | accurate; time consuming; expensive |
| Opiates | Natl: heroin & hydrocodone; synthetic: meperidine & methadone (less detectable) |
| Drug with longest detection time: | Benzo or THC |
| Drugs with lowest/highest detection thresholds: | Lowest: THC; highest: amphetamine |