Drugs of Abuse Screening (DOAS)

General Information

Drugs of Abuse screening (DOAS) may be ordered in a number of situations including:

• To evaluate drug use by the mother in pregnancy and presence of drug in neonates post partum
• To monitor adherance to substitute drugs (e.g. methadone) in patients known to be users of illict substances

Testing for drugs of abuse usually involves testing a urine specimen for a number of drugs. It should be noted, however, that a single urine drug test detects only fairly recent drug use and does not differentiate casual use from chronic drug use. The latter requires sequential drug testing and clinically evaluation. Also, urine testing does not determine the degree of impairment, the dose of drug taken or the exact time of use.

Classically, DOAS is performed via an initial immunoassay screen specific for a class of drugs (e.g. opiates). Since this is a non-specific screening technique, any positive results must be confirmed by a more specific technqiue, usually involving some sort of chromatographic seperation. The most widely accepted confirmatory method is GC-MS.

In order to avoid lengthly confirmation analysis and diagnostic confusion the Toxicology Department at Heartlands Hospital utilises a targeted drugs of abuse identification by liquid chromatography tandem mass spectrometry (LC-MS/MS). This technique has the distinct advantage of minimal sample preperation time together with being able to perform screening and identification of a range of compounds in a single run. Positive results represent concentrations of drugs above European Workplace Testing Thresholds. The following drugs are screened for:

Opiates - Morphine, Codeine, Dihydrocodeine & 6-monoacetyl morphine (6MAM)
Opioids - Methadone and metabolite (EDDP), Buprenorphine and metabolite (norbuprenorphine)
Amphetamines - Amphetamine, Methamphetamine, MDA, MDMA & MDEA
Benzodiazepines – Diazepam and metabolite (nordiazepam), oxazepam, temazepam, lorazepam, nitrazepam & midazolam
Designer drugs - Benzylpiperazine (BZP), MDPV (bath salts), 4-Methylethcathinone (4-MEC, NRG), 4-Methylmethcathinone (Mephedrone, Meow Meow)
Other drugs - Cocaine and metabolite (benzoylecgonine), Ketamine, Cannabis metabolite (11-nor-9-carboxy-tetrahydrocannabinol)

Drugs not listed here WILL NOT be detected by this technique. If you wish to screen for additional drugs please contact the Toxicology Laboratory on 0121 424 3235.