The BAR Rapid Test Dipstick (Urine) is a Rapid chromatographic immunoassay for qualitative detection of Barbiturate in human urine at a cut-off concentration of 300 ng/mL which is only utilized for in vitro diagnostics (IVD). It merely provides a preliminary result, therefore, an alternative method with more specificity is recommended to be used to confirm the initial results, in which case, the most preferred method is gas chromatography-mass spectrometry (GC-MS). For substance abuse cases, clinical considerations must be taken into account, especially when test results are positive.

Summary

Barbiturates are a group of drugs that affect the central nervous system and have a sedative and hypnotic effect. Barbiturates are used for many cases such as treating insomnia, treating anger and restlessness, anesthesia, etc. Barbiturates are addictive and their excessive consumption causes dependence. By binding to GABA nerve receptors and increasing their activity, barbiturates facilitate the entry of chlorine ions and have an inhibitory effect. The effects of barbiturates are, in many ways, similar to the temporary effects of alcohol. Small amounts produce calmness and relax muscles. Large doses can cause intoxication and drowsiness. Intoxicated by larger doses, the patient loses balance and dizziness and loss of speech will occur. In the case of overdose, it also causes unconsciousness, coma, and death. This drug is taken orally in the form of capsules or tablets. The short-term dosage of this medicine is 400 mg per day for 2 to 3 months. Only a very small amount of the drug (less than 5%) is excreted through urine. The detection period of barbiturates in urine is 4 to 7 days.

Rapid barbiturate urine test employs an immunochromatographic method based on competitive binding. Substances that may be found in urine specimen compete with ones metabolized by the liver to bind to antibodies. Dring the test, the urine specimen flows upward via capillary action. If the amount of barbiturate in the urine is below 300 ng/mL, it does not bind to the binding sites of the antibodies coated with gold nanoparticles. Consequently, the antibody conjugated with nanoparticles will be absorbed by the barbiturate on the surface of the membrane and will leave a colored line in the test area (T). Should the amount be greater than 300 ng/mL, no colored line will appear in the T area, since all the binding sites of the barbiturate antibodies are occupied. So, if the presence of barbiturate in the urine specimen is positive, no colored line will be formed in the test area (T) due to drug competition, whereas if the urine specimen contains barbiturate amounts lower than the desired level in the test, a colored line will appear in this area. In order to have a procedural control, a colored line always appears in the area of the control line (C), indicating the appropriate volume of the specimen added to the membrane.