Prescribing drugs of dependence in general practice

Part C2 - The role of opioids in pain management

Appendix C

Last revised: 02 Jun 2020

A baseline urine drug test (UDT) should be performed at the initial visit, with a request to include detection of oxycodone and other drugs not usually recognised by immunoassay such as fentanyl, tramadol, methadone and buprenorphine. These additional tests will be at extra cost to the patient.

C1.1 Screening and testing

Most urinalysis procedures are carried out using gas chromatography in specialist laboratories and there is usually a delay in receiving a result. The result establishes whether the drug/s is/are present but does not measure the amounts in which the drug/s has/have been taken. It can therefore be very helpful to have a supply of onsite urine testing strips that, within a couple of minutes, provide a basic guide to the drugs being used. This is a screening tool: it is not confirmatory, and should always be used in conjunction with clinical signs and history. False positives and negatives can occur with onsite tests, though they are rare.

Table C1.1

Table C1.1

Length of time drugs of dependence can be detected in urine481

C1.2 Interpreting urine drug tests

Unexpected results from such screens should be interpreted within their limitations: fentanyl, buprenorphine, synthetic drugs, anabolic steroids, and usually oxycodone are not routinely detected and must be requested as additional tests (at extra cost to the patient). Drug misusers may adopt a variety of methods, such as switching urine samples, to influence results.148

Table C1.2

Table C1.2

Interpreting unexpected results of urine drug tests102