Drugs of Abuse

Drugs of abuse testing detects residues of certain drugs or their metabolites in body fluids. Sonic Healthcare has been performing drug testing in clinical and workplace settings for many years.

The Sonic Clinical Institute situated at Macquarie Park in Sydney is a specialized reference laboratory, which is able to offer a rapid and high quality service for drugs of abuse testing. Through the Sonic Healthcare network of regional laboratories, collection centres, couriers and pathologists, the SCI is able to provide a national testing service involving collection, transport, testing and interpretation of samples and results.

Australian Standard for Drug Testing

The Specimen

The Collection Process

Urine samples are collected under supervision into specially designed beakers with temperature strips affixed. The supervising collector is specially trained in the requirements surrounding urinary drug screening and he/she records the temperature of the specimen and divides the specimen into three tubes. Each tube is labelled and signed by the client to verify identity. The tubes are then individually packaged with tamper evident tape and placed in secure tamper-proof satchels for transport to the laboratory.

The Chain-of-Custody Process

An audit trail is maintained such that every person involved in the collection, transport and checking process is required to sign either the chain-of-custody form or the transport form accompanying the specimens. The integrity of the samples and transport satchel is noted on the forms throughout the process. These forms are stored in a secure facility for future reference if required.

The Laboratory Testing Process

The initial test is a screening test which identifies a range of illicit and therapeutic substances. Screening is performed by immunoassay on the Hitachi 911 using Cedia reagents and methodology. Routine screening involves the testing of the following classes:

Testing can also be performed for additional drugs, including alcohol.

If the initial screening test is positive, a second unopened sample aliquotted from the original specimen is tested by a different method for confirmation of the initial result.

Confirmation of drug classes detected by Immunoassay is performed by gas Chromatography/Mass Spectrometry (GC/MS).

The presence of each drug or metabolite is tested for at or above a predefined cut-off level (see list below). These levels are dictated by International Standards for urine drug testing and defined in the Australian/New Zealand Standard AS/NZS 4308:2001. The “cut-off” levels are established because the aim of workplace testing is usually to identify significant residues of the targeted drug, not minute traces. For a result to be “positive”, the amount of the drug detected must be at or above the “cut-off” level. If a drug is detected but the level is below the “cut-off” the result will be negative. The “cut-off” levels for some classes differ for screening and confirmation. This is due to the non-specific nature of the screening assay versus the highly specific nature of the GC/MS confirmation.

Assay Integrity and Storage of Samples

Reporting Levels for Drugs of Abuse in Urine

Interpretation of Results

A confirmed positive result reveals the presence of a drug in the specimen at or above the “cut-off” level. It gives no information about how or when the drug was taken. It also does not provide an indication of impairment. A positive result may relate to previous drug use with no current physical effects. Positive results are reported as ‘Detected’, while a negative result is reported as ‘Not Detected’.

Drug Detection Times in Urine

The drug detection time is the time from the last dose of the drug until a negative screening result is obtained using the cut-off levels in the above table. Detection times vary with different drugs and different individuals and according to the amount and frequency of drug taken. It is important to note that whilst a drug may be excreted in the urine for a significant time, it may not reach the threshold required for a positive result. The following table lists the average detection times for a number of drugs.

Reports

Reports are available electronically, by fax or by hard copy.

Requesting Drugs of Abuse Testing

The Sonic Clinical Institute distributes a combined request and chain-of-custody form. This enables all the client details and the tracking of the specimen to be recorded on the one form. It is important to complete the form fully and correctly.
Ensure that the client’s full name, date of birth and date of collection are recorded on the form. Details such as medication which the client may be taking are important in interpreting the results of the urine drug test. Some preparations such as Paracetamol may cause an elevated screening result. It is therefore necessary in interpreting results to be aware of therapeutic drugs which the client may be taking.

Confidentiality

Client confidentiality is of the utmost importance. Strict security surrounds specimens and documentation. Results are released only to the requesting authority or directly to the client after thorough identification. All employees of Sonic Clinical Institute sign a confidentiality agreement when they are employed.

Time Taken for Result

Depending on time of arrival in the laboratory, samples are processed for screening either the same day or the morning after arrival in the laboratory. Hence negative screening results are available within 24 hours of the specimen arriving in the laboratory. Positive results are available within 48 hours of arrival in the laboratory (confirmation of 1 class). Second and further classes may take longer to analyse.

On Site Urine Testing

On site testing of urine samples offers a preliminary test result. Specimens are collected as outlined in the preceding paragraph and tested in individual testing kits usually for the five major classes of drugs. Positive on site screening results must be sent to the laboratory for screening by immunoassay and, if necessary, confirmation by GC/MS. On site screening provides a rapid method for excluding the presence of drugs but, due to the lack of specificity of on-site kits, it does not provide a dependable positive result. The SCI recommends regular quality control checks on negative results by correlation with the laboratory immunoassay screen.

Oral Fluid Testing

There is currently no Australian Standard to regulate oral fluid testing. However oral fluid is rapidly gaining popularity as a substance for testing drugs of abuse. Collection of sample is easy and there is no requirement for special collection facilities. There is, however, no link between urine and oral fluid results as drugs have different detection times in urine and oral fluid and different drugs and /or metabolites are present in these fluids. As for urine testing, oral fluid testing kits are designed to detect five main groups of drugs of abuse. Positive specimens must be tested in a laboratory with GC/MS methodology in order to obtain a confirmed analytical result.

The Sonic Clinical Institute is able to provide GC/MS confirmation testing for oral fluid samples.

The oral fluid samples are analysed for the presence of the following drugs:

Turn-around time for analysis of oral fluid specimens is 48 hours per drug class . Reports can be obtained electronically, by fax or hard copy.

SCI Staff

All staff in the Toxicology division of the Sonic Clinical Institute are qualified scientists, trained in immunoassay, GC/MS and the requirements of AS/NZS 4308. The division is led by Stacey Richards, a scientist with more than 6 years’ experience in the field of Toxicology. The division is directed by Dr Grahame Caldwell, a pathologist and specialist in the field of Toxicology. Both Stacey and Grahame are available for advice and interpretation of results during normal business hours.

SCI Laboratory Times of Operation

The Sonic Clinical Institute Toxicology Division currently operates Monday to Friday 0730-2200 and Saturday 0900-1600.
An oncall service is available for emergency testing outside of these times.

Contacts

Ms Stacey Richards
Manager Toxicology Division SCI
Tel 61 2 9855 5407
Fax 61 2 9855 5446
Email srichards@sonichealthcare.com.au

Dr Grahame Caldwell
Director Toxicology Division SCI
Tel 61 2 9855 5311
Fax 61 2 9878 5077
Email gcaldwell@dhm.com.au