any member of the subphylum Crustacea (phylum Arthropoda), a group of invertebrate animals consisting of some 45,000 species distributed worldwide. Crabs, lobsters, shrimps, and wood lice are among the best-known crustaceans, but the group also includes an enormous variety of other forms without popular names.
It is thought that infrequent, low-dose users may test positive for Xanax within urine for up to 4 days post-ingestion. Frequent, high-dose users of the drug may test positive for Xanax after a full week post-ingestion via a urinalysis. Results from a urinalysis can be confirmed with technology such as GC/MS.
Urine tests are the most commonly used, but the length of time that Xanax stays in this bodily fluid depends largely on how heavy abuse of the drug has been. For occasional users, a urine test will usually not work past 4 days, but in heavy users, it can detect the substance for up to a week. Saliva and blood tests work on a much shorter timeline. Though they can detect Xanax soon after a dose is taken, saliva tests only work for 2.5 days after the last dose, and blood tests are only effective for a day. Hair tests can detect Xanax for up to a month after the last dose as traces of the drug accumulate in the hair follicles. However, it takes much longer for a drug to appear in hair than in bodily fluids, so if a hair sample is taken too soon after someone takes Xanax, the sample may come back negative for the drug.