ABSTRACT
Morphine is a nitrogen-containing basic drug isolated from the opium poppy (Papaver somniferum) and denes the group of opiate functional and structural analogs with such well-recognized examples as codeine, hydrocodone, oxycodone, fentanyl, methadone, and meperidine. Naturally occurring structural analogs of morphine that possess similar biological activity are called the opiates, while opioids refers to all compounds that are able to function in whole or in a manner similar to morphine, regardless of structural similarity or lack thereof. (us, morphine is an opiate, hydrocodone is a semisynthetic opiate, and fentanyl is an opioid.)
Interpretation of toxicologic ndings involving these compounds can be a challenging task, made more complicated by the variability of sensitivity of individuals to the opioids (a function of both their genetically related expression of receptors and development of tolerance with prolonged use). Such variability of sensitivity to the eects of the opioids also complicates the prescription process, in that a therapeutic level for one individual may be toxic in another, and the dose that was adequate for pain relief in a naïve user can become less eective or inadequate as tolerance develops. For this reason, opioid levels are generally not evaluated by therapeutic drug monitoring (TDM; the monitoring of drug levels in blood and adjustment of dose to achieve a targeted steady-state concentration range), despite the ready availability of relatively fast and accurate quantitative analytical procedures. Rather, opioid doses are adjusted to the individual patient (titrated) so as to achieve a requisite level of analgesia, while hopefully avoiding an unacceptable degree of side eects or potential for abuse. Further complicating the understanding and interpretation of opioid results for the forensic toxicologist and pathologist may be the presence of other drugs, both recreational and medicinal, as well as
SIDEBAR 13.1 ROUTES OF ILLICIT DRUG ADMINISTRATION
It is not common that the manner in which a drug has been brought into the system is of forensic interest; however, such questions do occasionally arise. Although the methods of drug use (e.g., ingestion, inhalation, injection) are not limited to the opioids, because of the long history of this group and the variety of both legal and illicit preparations, a wide variety of usage schemes have been, currently are, and doubtless will continue to be demonstrated with the various opioids. While the various means and mechanisms of injection (and injection sites) are well known, the availability of opioids in pill and patch form has resulted in some novel drug use systems.
