DRE DRE Toxicology & Drug Testing 2 — Questions and Answers
Question 1: Which type of drug interaction occurs when two substances together produce a greater-than-additive effect?
- Antagonism
- Tolerance
- Synergism (Correct answer)
- Cross-tolerance
Correct answer: Synergism
Synergism (or potentiation) occurs when two drugs combine to produce an effect greater than the sum of their individual effects, increasing impairment risk.
Question 2: A urine immunoassay screening test that returns a positive result must then undergo which step before being admissible in court?
- A second urine screen
- GC-MS confirmatory testing (Correct answer)
- Field sobriety re-testing
- Blood pressure recheck
Correct answer: GC-MS confirmatory testing
Positive immunoassay screens must be confirmed with GC-MS to provide the specificity and precision required for court proceedings.
Question 3: Hallucinogens such as LSD primarily affect which neurotransmitter system, which DREs should understand when correlating findings?
- Dopamine
- GABA
- Serotonin (Correct answer)
- Acetylcholine
Correct answer: Serotonin
LSD and other classic hallucinogens exert their effects primarily through agonism at serotonin (5-HT2A) receptors, producing perceptual distortions.
Question 4: What is the half-life concept important for in a DRE toxicology context?
- Determining how quickly the suspect can drive again
- Estimating when a drug's concentration decreases by 50% (Correct answer)
- Setting the legal per se limit
- Calculating the officer's response time
Correct answer: Estimating when a drug's concentration decreases by 50%
Half-life describes the time required for the plasma concentration of a drug to decrease by half, helping DREs understand the duration of likely impairment.
Question 5: Dissociative anesthetics like PCP can produce which unique toxicological finding relevant to a DRE evaluation?
- Miosis
- Horizontal gaze nystagmus without alcohol (Correct answer)
- Bradycardia
- Hypothermia
Correct answer: Horizontal gaze nystagmus without alcohol
PCP and other dissociative drugs can produce horizontal gaze nystagmus (HGN) independent of alcohol ingestion, which must be distinguished during evaluation.
Question 6: Which term describes the time from drug ingestion to when peak blood concentration is reached?
- Half-life
- Onset time
- Time to peak (Tmax) (Correct answer)
- Clearance time
Correct answer: Time to peak (Tmax)
Tmax (time to maximum concentration) indicates when the drug is at its highest level in the blood, which often correlates with peak impairment.
DRE DRE Toxicology & Drug Testing 2
Which type of drug interaction occurs when two substances together produce a greater-than-additive effect?