This figure is likely derived from the mathematical observation that 0.55 (50% elimination, five times) equals 0.03125, suggesting that only 3% of a drug remains following five half-lives.
However, this approach may not be appropriate in every case.
In contrast, a "positive" urine drug screen by itself is not confirmatory, but in the setting of an appropriate history, clinical presentation and physical examination can support intoxication.
Although most hospital laboratories can readily measure serum concentrations of some common drugs in overdose, including lithium, digoxin, phenobarbital, phenytoin, and valproic acid, there are many drugs that cannot be measured in a clinically relevant time frame.
The American College of Medical Toxicology supports the intent of the Federal Regulations which requires Safety Data Sheets (formerly Material Safety Data Sheets) as part of communications to improve safety in the workplace.
It is the position of ACMT that the format of the SDS should not be expanded to serve as a mechanism to communicate to practitioners of medicine advice on treatment of the health effects of chemical exposure other than first aid measures.
Mechanisms of metabolism may be saturated in overdose .
As an example of prolonged half-life in overdose, many references indicate the half-life of baclofen is approximately 2–4 h, but in overdose, the duration of effect far exceeds the recommended five half-life calculation .
The individual or organization responsible for the content should be identified and the source of listed health hazards should be cited.As an alternative, the SDS should include a referral mechanism through which advice on treatment is available from a physician board-certified in medical toxicology.