Testing for Controlled Substances

Transcription

1 Testing for illicit drugs Testing for Controlled Substances 1 Purposes: Employment Sports Screening medical eval. Legal Monitoring Treatment Probation Prescribing controlled substances Forensics 2 Drug Testing Urine Hair Sweat Saliva Blood Meconium Drug Testing Use for monitoring pts that you prescribe controlled substances Benzodiazepines Opiates Stimulants But also looking for evidence of other drug abuse 3 4 1

2 Monitoring controlled substances Pill counts KS PMP Urine 2 step process Screening Immunoassay On-site or in lab First step If neg., no further testing* Confirmation GC/MS or TLC Usually on request (pos. specs. saved 1-3 weeks) 5 *unless unexpected 6 : Routine panel: Opiates (not comprehensive) Marijuana Amphetamine/methamphetamines Cocaine PCP Alcohol must order separate EtG metabolite extends detection time Must specify others: eg. Bz, Barb, methadone, SOMA, tramadol, fentanyl 7 Specimen validity testing Screening for adulteration, dilution, or substitution Creatinine Temperature SG Adulterants ph (<3, >11) Appearance Observed collection 8 2

3 Dilution parameters: Dilute Creat. >= 2, but < 20 SG > (or with > ) Substituted Creat. < 2 SG <= (or with > ) 9 beat a drug test 17,200,000 hits 10 Urine Drug Testing - problems What constitutes a positive test? Drug is detected in concentrations above predetermined cutoff levels (both screening and GCMS) False negatives False positives Dilute urine (Creat. < 20) Substituted urine (Creat. < 2) Adulterated urine

4 Reasons for a negative test: Drug not there Drug not detected by test Drug below the cut off concentration False negative 13 reasons for a false negative test False negatives Below cut-off Dilute urine Drug has cleared or recent use Infreq. use or small amount used Tampering Can order no cut-off (no threshold) test, Or special panels (eg.: pain mgmt.) 14 - opiates: Screening is reliable for: Natural opiates: codeine, morphine Screening less reliable for: Semisynthetics: hydrocodone, oxycodone, hydromorphone Screening not reliable for: Synthetics: fentanyl, propoxyphene, methadone, buprenorphine; Pain mgmt. panel (opiates) Adds semi-synthetics and synthetics Increased sensitivity Lowered thresholds 100 ng/ml - from 2000 ng/ml Morphine: Metabolite of codeine, heroin Also in poppy seeds Not methadone, oxycodone, etc. or for clonazepam

5 What about metabolites? Urine Drug Testing Understand the metabolites of what you prescribe. Bz and opiates do not all have the same metabolite. False positives Screening only Confirmation no false neg/pos Confirmation Medical review GC/MS : False positives (examples) Cipro for opiates Pseudoephedrine for amphetamines Venlafexine for PCP NSAIDs for THC Cocaine Poppy seeds (for morphine) Confirmation testing GC/MS gold standard No false positives Requires order for confirmation of result Will include quantitative result

6 Sample report 21 6

7 dealing with positive results : challenges Is it expected or unexpected? Is it a prescription drug or illicit? If prescription, verify Rx Contact prescriber or KS PMP If possible OTC, confirm result (GCMS) Exception: poppy seeds Example: Screening pos. for methamphetamine Pt. claims never used Adds: I use Vicks NS GC/MS confirms presence of methamphetamine Isomeric testing d and l isomers d = drug l = legal (eg. Vicks) What about marijuana? Casual use Chronic use Medical use Status: An illegal drug! And if legalized, is it approved? By employer, physician 24 What about marijuana? Positives: MJ use Marinol (cannot differentiate) False pos. (rare) Not due to passive contact Will typically have a level (ng/ml) Infreq. use usually less than 100 Freq. use usually greater than

8 Marijuana levels With chronic and/or heavy use, can persist for weeks Use the THC/creatinine ratio to compare levels Adjusts for urine concentration Marijuana levels Week 1 Week 3 THC Creat THC/Cr THC Creat THC/Cr : timing Other testing Approximate detection times: Amphetamines 2-4 days Cocaine 2-4 days Opiates 2-4 days THC days Bz 2-3 days Barbs 2-3 days Long acting drugs, heavy drug use: will be longer Hair Sweat Saliva -most drug metabolites -2 gives 3 month history -as long as left in place -tamper proof patch -less than 24 hrs THC pos. is not due to passive inhalation 28 All can be GC/MS confirmed 29 8

9 Summary Not a diagnostic test! Indicates usage not timing or amount Use does not equal abuse/dependence Excellent monitoring test Encourages personal honesty Confirmation process Personal history GC/MS MRO training Medical review officer Certification (only req d for regulated tests) CME required every three years AAMRO, ASAM provide training Urine Drug Screening: A Valuable Office Procedure Standridge, J. et al, AFP, March 1,2010, Vol. 81 (5), pp Questions? Urine Drug Testing in Clinical Practice California Academy of Family Physicians