Clinical Toxicology: Drug Testing and Monitoring
Explore the critical role of drug testing in clinical toxicology, from screening methods to confirmatory techniques. Learn about the types of tests, their applications, and the challenges in interpreting results.
Why Drug Test?

1

Assess Symptoms
Determine if drugs contribute to a patient's condition.

2

Diagnose Abuse
Make initial diagnoses of drug abuse or addiction.

3

Monitor Compliance
Ensure patients adhere to medication regimens.
Types of Drug Testing
Urine
Most common, applicable in any industry setting.
Saliva
Preferred for on-the-spot drug testing.
Hair
(Forensic only) Offers long 90-day detection timeframe.
Urine Drug Testing: Advantages and Limitations
Advantages
  • Inexpensive to analyze
  • Easy to collect
  • Concentrates drugs and metabolites
  • Long detection window (1-3 days)
  • High sensitivity
Limitations
  • Potential for adulteration
  • May not detect very recent use
  • Can't determine exact time of use
Drug Testing Stages

1

Initial Screening
Uses immunoassays or point-of-care devices for quick, qualitative results.

2

Confirmatory Testing
Utilizes GC/MS or LC/MS/MS for specific, quantitative analysis of positive screens.

3

Result Interpretation
Considers factors like cross-reactivity and metabolite presence for accurate diagnosis.
Immunoassay: Pros and Cons
Advantages
  • Quick results
  • Inexpensive
  • Detects multiple drugs in a class
Disadvantages
  • Qualitative results only
  • Not highly specific
  • Cross-reactivity issues
Cross-Reactivity
Similar molecules can trigger false positives, e.g., cold medications in amphetamine tests.
Confirmatory Testing with LC/MS/MS

1

Sample Preparation
Concentrate analytes and remove interfering substances.

2

Chromatography
Separate compounds based on chemical properties.

3

Mass Spectrometry
Identify and quantify specific drug molecules and metabolites.

4

Data Interpretation
Analyze results using Multiple Reaction Monitoring (MRM) for high specificity.
Common Pain Management Drugs
Codeine
Moderate pain relief medication requiring careful prescription monitoring and regular testing.
Fentanyl
Powerful synthetic opioid that demands strict monitoring protocols and frequent testing.
Hydrocodone
Common pain medication that requires thorough documentation and regular screening.
Oxycodone
Strong opioid medication necessitating careful monitoring to prevent misuse.
Pain management drugs like codeine, fentanyl, hydrocodone, and oxycodone require careful monitoring due to their potential for abuse and addiction. Drug testing plays a crucial role in ensuring proper use and preventing misuse of these powerful medications.