So if im clear, to be totally sure that the tests will not come up positive you should wait 72 hours before driving after taking ecstasy or amphetimines?
With an estimated 2-4 hour cutoff point I'd say that 72 hours would more than suffice. However, my concern lies with those who are chronic users. We still don't know if clearance will generally be increased, decreased or unaffected in these people.
As mentioned, because individuals often metabolise various drugs at significantly different rates, expected "clearance time" ( defined in this case as when the test no longer shows a positive) will also vary. This may be further affected by certain pharmaceutical medications.
Immunolabeling tests work by employing 2 (sometimes more) immunolabeling chemicals. One is a principle antibody and the other is usually bound to a metal (in this case gold) which produces the colour or fluorescence when bound to the
principle antibody. However, before being able to bind, the principle antibody, usually an endogenous or modified endogenous compound, has to first bind with the drug or metabolite. This initial binding is quite selective (although it will often bind with structurally similar compounds e.g. methamphetamine and MDMA)
The drugwipe (initial screening) test is designed to pick up the presence of the drug itself or initial metabolites. Once the drug is further metabolized and the identifiable compound/s reduced to levels below detection limits, the tests should give a negative. As can be imagined with most drugs,
other drug metabolites are still present long after intoxication has subsided but because of their chemical structure, they cannot bind with the antibody.
To be sure, and thereby both comply with the law, and minimise any personal inconvenience, I would suggest obtaining a few drug wipe kits and doing the tests yourself. Although the roadside test also uses a detector, providing the tests are read under adequate lighting, this isn't required (a magnifying glass may also help).