Drug test

A drug test is an examination method to determine the type and amount of drug or medicament in the body of a person or animal. A drug test is usually carried out on suspicion of abuse .

Analytical determination

The use of analytical methods should primarily be based on the task at hand. The following considerations should be made when testing drugs:

Which drugs should be determined ( analytes ) in order to make which statements (occasion)?
How long ago was a questionable drug use (hours, days, weeks, months or chronic)?
This results in which examination materials come into question and
which method or which tests are suitable in principle (analytical requirements).
To what extent are the possible procedures usable routinely or for the intended occasion?

Immunological pre-tests

An immunochemical preliminary test with a lateral flow test can be carried out on the samples to streamline the tests . In this way, samples can be preselected quickly, sensitively and without extensive preparation for the presence of different active ingredients or active ingredient classes. The principle of cross-reactivity is used for this, so that an entire group of substances can be tested with one test .

Testing on an immunological basis has its origins in the USA , where immunassays for drug detection, in addition to their use in the toxicological field, have been used to a large extent since the end of the 1980s as part of pre-employment testing or to monitor drug freedom at work ( "Workplace testing") can be used. As a result, many manufacturers of immunassays used American criteria to specify the decision limits between “positive” and “negative” (so-called “ cut-off values ”). H. the requirements of the NIDA . For many years, however, more sensitive tests with lower cut-offs have also been offered. Some of the cut-offs are legally stipulated, but mostly they are set by the test manufacturers.

All assays are based on the principle of the antigen-antibody reaction , according to which the substances sought compete with antigens for binding with specific antibodies . The number of immune complexes formed from antibodies and analytes allows a statement to be made about the concentration of the analyte in the sample. However, the antibody-antigen binding is not directly accessible analytically in most immunassays. This problem is solved in that one of the two components, the antigen or the antibody, is coupled with an easily detectable marker substance, e.g. B. with an enzyme ( biocatalyst ), dye, fluorophore or more rarely with a radioactive component.

There are two main types of drug immunassays that are widely used: test strips (sticks) or test cassettes for quick, manual on-site determination ( rapid drug tests / POCT ) and automated liquid reagent tests , which are usually carried out in laboratories (often as Abbreviated “EIA”, but there are many other designations that are often brand names, e.g. CEDIA , KIMS , Syva and others). Compared to test strips / cassettes, EIAs often allow a lower cut-off, ie smaller amounts can be detected. But above all reading errors - the most common source of error in test strips - virtually ruled out by the automated measurement and EIAs have a much higher precision and accuracy .

In addition to being used in urine testing , immunoassays can also be used to detect drugs in other body materials. There are EIAs and microtiter plate tests on the market, which are enzyme-immunochemical and very sensitive to the detection of drugs or metabolites, e.g. B. in whole blood or serum .

Drug immunassays are pre-tests; H. do not provide a final result:

Immunassays provide valuable information on the drug content of the samples examined, but the results obtained must be backed up by using other conclusive procedures with higher specificity (confirmation procedure). This is because, due to the cross-reactivity of the immunassays, false positive results are particularly common; There are also reading errors with test strips. Reliable identification and exact quantitative determination can only be guaranteed through confirmation procedures .

Confirmation procedure

A conclusive quantitative determination of the various drugs from a complex matrix such as B. the serum requires the use of a selective method. The low concentrations in the nanogram range of drugs in the blood, but also in the saliva , make the use of complex analytical determination methods necessary, which also enable measurements close to the detection limit .

Numerous methods for identification and quantitative determination from physiological sample materials are described in the literature, the combination of liquid chromatography or gas chromatography with mass spectrometry with stable isotopes being preferably used as internal standards. Gas chromatography-mass spectrometry ( GC / MS ) has long been known as a “definitive method” that is characterized by being “correct” and specific; it provides a definite (correct) value as the best approximation of the "true value". The GC-MS is also listed as a “confirmatory drug test” in the “Mandatory Guidelines for Federal Workplace Drug Testing Programs” in the USA. In addition, liquid chromatography, HPLC, especially coupled with a mass spectrometric detector ( LC / MS ), is increasingly used as a definitive method .

Investigation material

Analytical detection windows for different test materials

In order to determine whether medication or drugs are contained in the body, toxicological analyzes can be carried out with various body materials. These are to be selected depending on the question; For example, recent consumption can be detected in saliva and blood, while hair, as a “ tachograph ” , enables a better insight over a longer period of time.

Analytical detection windows for different test materials .

blood

The blood is very suitable for testing for drugs and medication, as it contains the substance in question from the time it is administered and transports it to all tissues, including the sites of action and the organs that remove it from the organism. Blood cannot be manipulated, its composition is quite uniform and the active ingredient concentration is in dynamic equilibrium with the concentration of absorbed substances in the central nervous system and thus, at least to a limited extent, related to an effect. For all these reasons, from a police and traffic law point of view, only blood as test material fulfills the German legal requirements of Section 24a (2) of the Road Traffic Act . Since tolerance is compulsory in Germany, the blood collection can be ordered by the police in the context of committed traffic offenses . However, the collection is highly invasive and therefore not suitable for testing "on site". The foreign substances to be examined or their metabolites occur in lower concentrations in the blood than in the urine, which is why consumption can only be detected for a comparatively short time (depending on the substance, a few hours to days). This is a disadvantage for general abuse screening , and an advantage for police and legal issues.

urine

For many questions, urine is the material of first choice. The examination of urine is an important addition for other questions. As a test material, urine has the advantage that it can usually be given off in large quantities by the test person without invasive techniques . In general, the foreign substances or their metabolites are present in higher concentrations than in the blood and can be detected for longer. The broader metabolite profile can also provide additional information. The disadvantage, however, is that it can only be compared to the blood result to a limited extent. In most cases, measurable concentrations can be found in the blood immediately after consumption, while the drug's degradation process in the body means that detection in the urine is not possible or is hardly possible. Foreign substances or their metabolites can be detected in urine (depending on the substance) for a few days to weeks . For this reason, positive evidence in the urine does not necessarily mean that consumption occurred in the past ; Especially with cannabis consumption, the main breakdown product used for detection, the THC carboxylic acid , is still present in the urine up to weeks later.

The THC urine test can be influenced by passive inhalation. Drug urine tests that are set too aggressively with regard to THC (detection limit (cut-off) less than 50 ng / ml) could give a positive result in people who have inhaled cannabis-containing air without smoking (passive smokers). To exclude passive smokers, tests with a limit value of 50 ng / ml should be used.

The need for suitable locations for the submission of a urine sample made or makes a high expenditure of time and personnel necessary. Preserving the privacy of the tested person is impossible, especially when the release is observed (so-called "direct view") . A urine output by the test subject can also be manipulated in a variety of ways. For evidence of abstinence in the context of an MPU ( medical-psychological examination ), urine sampling under direct vision is mandatory. For other questions, there is an alternative that enables reliable sample assignment without direct vision, the Ruma marker. At first the marker system was not widely used. However, since the process has been used by several providers, its spread has increased.

saliva

The (physiological) saliva is colorless and transparent, has a low viscosity and is formed by the salivary glands in and around the oral cavity. These glands secrete about 1–1.5 liters of saliva daily. As a test material, saliva offers an informative statement about the current drug influence, since, similar to the blood samples, more up-to-date references to the time of drug consumption and the degree of effect can be made than with the examination of urine. There are fewer problems with the collection of saliva samples than with the collection of a urine sample: the privacy of the test persons is not significantly impaired and the sample collection can therefore take place directly at the test site under constant supervision without the need for special facilities. Therefore, the time and personnel required to carry out the test is less than for urine tests. People who have been tested are generally more willing to perform a saliva pre-test than a urine pre-test. Possible sample manipulations by the test person are largely excluded. The concentrations of most drugs are higher in saliva than in blood. Saliva tests are often used as screening tests for police measures and for controls at the workplace, where the question of a current influence on the test subjects arises.

Hair / nails

Also keratinous material such as hair or nails can be used as analytical material. By including drugs in the keratin structure, taking into account the average hair growth length (approx. 1 cm / month), statements can be made about the “drug career” of the person examined and, to a certain extent, about consumer behavior. However, the examination cannot provide any information on acute drug use. The use of hair or nails as test material does not make sense for a preliminary test.

→ See also : Hair analysis

teeth

Tooth substance ( dentin ) can be used as evidence of drug and medication consumption. For testing for morphine, codeine, ecstasy, MDEA, amphetamine, metamphetamine, cocaine and a cocaine breakdown product, you only need 0.05 grams of tooth substance, which, with the aid of a liquid chromatograph coupled to a mass spectrometer, provides evidence of drugs.

literature

Drugs and addiction report of the federal government. As of April 2004. Available at http://www.bmgs.bund.de/

CW Chiang, G. Barnett: Marijuana effect and delta-9-tetrahydrocannabinol plasma level. In: Clin Pharmacol Ther . 36: 234-238 (1984).

Federal Highway Research Institute (BASt) (ed.): Drug detection in road traffic - training program for police officers. (Reports of the Federal Highway Research Institute, People and Safety, M 96). Wirtschaftsverlag NW. Verlag für neue Wissenschaft, Bremerhaven 1995, ISBN 3-89701-235-9 .

R. Aderjan: Toxicological proof of cannabis. In: G. Berghaus, HP Krüger (ed.): Cannabis in road traffic. Gustav Fischer Verlag, Stuttgart 1998, pp. 153-178

National Institute of Drug Abuse: Mandatory Guidelines for Federal Workplace Drug Testing Programs. Draft 4 (2002). (online at: workplace.samhsa.gov )

R. Polzius, A. Manns: Immunoassays: A highly sensitive and selective analysis technique. Drägerheft 373, 2002, pp. 23-28

German Medical Association: Guidelines of the German Medical Association for quality assurance in medical laboratories. (until December 31, 2001) (1993); http://www.bundesaerztekammer.de/page.asp?his=1.120.121.1047.1053

YH Caplan, BA Goldberger: Alternative specimens for workplace drug testing. In: J Anal Toxicol . 2001 Jul-Aug; 25 (5), pp. 396-399.

Web links

Wiktionary: drug test - explanations of meanings, word origins, synonyms, translations

Individual evidence

↑ ^a ^b Wolfgang Schubert, Rainer Mattern (ed.): Formation of judgment in the medical-psychological diagnosis of fitness to drive. 2nd Edition. Kirschbaum Verlag, Bonn 2009, ISBN 978-3-7812-1678-5 .

↑ ^a ^b Fritz Pragst : Book Review: judgment Psychological Medicine-in Fahreigungsdiagnostik - Assessment criteria 2nd edition. Toxichem Krimtech 2009; 76 (3): 256-257. Retrieved January 4, 2014 .

↑ Volker Sominka: Aggressive or Conservative Urine Tests ? Using the example of THC passive smoking. In: www.kriminalpolizei.de. July 7, 2008, accessed July 7, 2008 .

^ Laboratory Lademannbogen: Substitution therapy and Ruma marker. Retrieved December 31, 2013 .

^ Willfried Schramm, Richard H. Smith, Paul A. Craig, David A. Kidwell: Drugs of Abuse in Saliva: A Review . In: Journal of Analytical Toxicology . tape 16 , no. 1 , January 1, 1992, ISSN 0146-4760 , p. 1–9 , doi : 10.1093 / jat / 16.1.1 ( oup.com [accessed February 24, 2018]).

↑ Kaarina Langel, Hallvard Gjerde, Donata Favretto, Pirjo Lillsunde, Elisabeth Leere Øiestad: Comparison of drug concentrations between whole blood and oral fluid . In: Drug Testing and Analysis . tape 6 , no. 5 , May 1, 2014, ISSN 1942-7611 , p. 461-471 , doi : 10.1002 / dta.1532 ( wiley.com [accessed November 20, 2017]).

↑ Sarah MR Wille, Elke Raes, Pirjo Lillsunde, Teemu Gunnar, Marleen Laloup: Relationship Between Oral Fluid and Blood Concentrations of Drugs of Abuse in Drivers Suspected of Driving Under the Influence of Drugs . In: Therapeutic Drug Monitoring . tape 31 , no. 4 , p. 511-519 , doi : 10.1097 / ftd.0b013e3181ae46ea ( ugent.be [accessed November 20, 2017]).

↑ Saliva test: A small saliva sample with a big effect. Catalog of fines 2017, accessed on November 20, 2017 .

↑ Guidelines for Testing Drugs under International Control in Hair, Sweat and Oral Fluid. Manual for Use by National Drug Analysis Laboratories. United Nations Office on Drugs and Crime, 2014, accessed November 20, 2017 .

↑ J. Spinner1, M. Klima, J. Kempf, LM Huppertz, V. Auwärter, MJ Altenburger, MA Neukamm: Determination of drugs of abuse in bovine dentin using liquid chromatography – electrospray ionization tandem mass spectrometry. Retrieved February 8, 2015 .

[MPU-Beurteilungskriterien-1] Wolfgang Schubert, Rainer Mattern (ed.): Formation of judgment in the medical-psychological diagnosis of fitness to drive. 2nd Edition. Kirschbaum Verlag, Bonn 2009, ISBN 978-3-7812-1678-5 .

[MPU-Buch-Besprechung-2] Fritz Pragst : Book Review: judgment Psychological Medicine-in Fahreigungsdiagnostik - Assessment criteria 2nd edition. Toxichem Krimtech 2009; 76 (3): 256-257. Retrieved January 4, 2014 .