Drug testing in urine sample.

INTRODUCTION

Drug testing has a number of purposes in clinical and other practices, each of which requires a clear testing strategy. Urine is generally “the best” biologic specimen for determining the presence or absence of most drugs because it has a 1- to 3-day window of detection for most drugs. In contrast, drugs and or their metabolites would be detectable for only a matter of hours in serum. Since serum drug testing also suffers from the disadvantages of increased cost and invasive nature, urine is the preferred biologic sample (Graham et al, 2008).

The term urine drug “screening” is a misnomer since it implies screening for all drugs. Firstly, in reality, it is not possible to prove the presence or absence of all drugs, and the testing process is open-ended and evolving. Secondly there is no “standard” urine drug test (UDT) which is suitable for all purposes and settings rather, a multitude of options exists that healthcare professionals should adapt to their clinical needs. The healthcare professional must advise the testing laboratory whether the presence of any particular substance or group of substances is suspected or expected. Accurately interpreting UDT results requires the healthcare professional to take a detailed history of the medications a patient uses, including over-the-counter (OTC) or herbal preparations, documentation of the time of their last use, and knowledge of which preparations, or their metabolites, may cross-react or interfere with immunoassays (Talaro, 1999).

There are typically two types of urine drug testing. These approaches used in proper combination can reduce cost, ensure accuracy, and improve efficiency. Although a range of technologies is available, from single-use devices to fully automated laboratory platforms, the two main types of UDT are: 1. Immunoassay drug testing, either laboratory based or at POC (e.g., “dip-stick” testing). 2. Laboratory-based specific drug identification (e.g., GC gas chromatography, high-performance liquid chromatography [HPLC]). The method chosen to detect a particular drug will depend on the reason for undertaking the test (Talaro, 1999). The immunoassay drug tests are the most common methods, which are designed to classify substances as either present or absent according to a predetermined cutoff threshold. In some cases, specific drug identification using more sophisticated tests is needed. Such combined techniques permit accurate identification of a specific drug and or its metabolites. Immunoassays, which are based on the principle of competitive binding, use antibodies to detect the presence of a particular drug or metabolite in a urine sample. The principal advantage of immunoassays is their ability to simultaneously and rapidly tests for drugs in urine (Graham, 2008).

In this report will be mainly focusing on the urine sample that was collected at a crime scene just before the victim died. A team of forensic investigators arrived at a crime scene which had been reported that a certain boy started hallucinating and running around the school premises after he was said to have consumed an excessive amount of a drink which had an unknown drug. The boy had consumed the drink in large amounts to an extent that he started vomiting and defecated soon before he died. The forensic investigators managed to collect a sample of urine just before the boy died. We collected urine because urine is ideal because it allows investigators to determine if drugs have been taken in the recent past. As the body processes drug metabolites can be found in different mediums at different times.

There are many types of testing kits which can be used to test samples at the crime scene. There are test strips and test cassette which are for single drug types. Then there are also multipanel, multicassettes and integrated cups which can be used to detect 2 to 12 drug types simultaneously. The strips are dip and react test for 5 minutes which has an accuracy percentage greater than 99%. For the cassettes use a transfer pipette to transfer the sample into the cassettes (Mader, 2004). In this investigation a multi cassette was used to detect drugs in the urine sample.

AIMS

To carry out a drug test in the urine provide and determine the drug.

OBJECTIVES

To collect urine sample.
To test and analyze the urine sample for drugs.

MATERIALS AND METHODS

The materials used were the multi cassette, list of drugs to be tested, dropping pippete and the urine sample.

Three drops of the urine sample were dropped on the cassette, waited for 5 minutes and observed the results.

RESULTS

Fig1; multi-cassette for urine drug test.

Download full document here

DISCUSSION

Laboratory analysis of a sample is often performed in two stages. The first analysis is performed using immunoassay technology and is often called a “presumptive” test. Most commercially available immunoassay kits are screening tests for the common drugs of abuse like cocaine, methamphetamine, marijuana, phencyclidine, morphine etc., although some kits are available for testing other types of drugs such as the benzodiazepines and the phenothiazine. Presumptive drug screening is simple to perform, but difficult to interpret. Most immunoassays are called “presumptive tests,” since a positive reaction is an indication that a drug or drug class is present, yet the method does not rise to the required level of certainty. Confirmation by a second test is required. The main reason why presumptive tests are not used forensically is because there is considerable cross reactivity with drugs other than the target drug (Talaro, 1999).

Urine is suitable for the determination of recent use, especially during the past seventy-two hours. The time frame in which a drug may be detected depends on several factors, including the amount of drug initially consumed, the frequency of drug use, the lipid-solubility of the drug in question, and the half-life of the drug. Another benefit to using urine for drug testing is that drug concentration in urine is ten to one-hundred times more concentrated than in the blood, making detection easier using conventional drug-testing instruments (Graham et al, 2008).

From the cassette it in the figure1 there are two bands for each drug which means they are negative in the boy’s system. This could give a conclusion that the drink which the boy consumed did not contain the drugs. The boys might have been poisoned; the investigators took the urine sample, other biological samples and the container of the drink for further examinations to find out if that was what killed the boy. However results can also be false positive or false negative depending on a number of reasons and factors. But in most cases a negative result is considered a good thing. In other cases the false negative results could be of threshold issues. Some of the drugs like BZO are medical drugs which can lead to death if consumed in excess.

REFFERENCES

Graham I, Brooker R, Wedmier E, Stiling P (2008). Biology .McGraw Hill, New York.
Mader S, (2004). Biology, 8th edition. McGraw Hill, New York.
Talaro K and Talaro A, (1999). Foundations in microbiology, 3rd edition. WCB McGraw Hill. Boston.