Opiates are a very old class of drugs derived from the exudate of the opium poppy and used for centuries for pain relief. Morphine is the principal alkaloid in opium and the name morphine was derived from the Greek god of dreams – Morpheus. The psychological effects of opium were known to the ancient Sumerians, but the first undisputed reference to the opium poppy dates from the third century B.C. Like so many drugs, modern chemistry has extensively experimented with the drug’s chemistry, resulting in more useful, potent, and addictive opioid derivatives. The invention of the hypodermic needle increased the abuse of morphine. The smoking of opium by the Chinese workers in the late 1800’s, use of morphine for Civil War casualties, and lack of regulation until the first part of the 20th century all contributed to the rise of opioid abuse. Heroin, a very potent opioid, was synthesized for use during the Civil War resulting in the addiction of many Civil War soldiers.
Opioids are the preferred term referring to the large chemistry of exogenous substances binding to opioid receptor sites producing agonistic effects. Opioids share some of the properties of naturally present peptides called endorphins and enkephalins. Opioids have specific receptor sites causing the effects which may be specifically blocked by opioid antagonists such as naloxone or naltrexone, related chemical structures that will bind to the receptor displacing opioids. This drug is used as an antidote to opioid overdose.
Morphine, heroin, codeine, and many related synthetic opioid analogues produce their major effects on the central nervous system (CNS) and the bowel. Effects are diverse including analgesia, drowsiness (nodding), changes in mood, respiratory depression, and decreased gastrointestinal motility. Pupils are constricted and not responsive to light stimulus. Heroin, the most abused and addictive opioid, is synthesized from morphine by acetylation to diacetylmorphine. After intravenous injection, it is rapidly diacetylated to morphine and further metabolized by the liver to other urinary metabolites including codeine. Codeine is also a popular oral medication. For an opioid addict, heroin is preferable but they will use any available opioid. Methadone is a synthetic opioid which has agonistic actions, but has relatively weak effects on mood and is used to “maintain” opioid addicts. Naltrexone (Trexan) is also useful as a long term antagonistic.
Laboratory detection of morphine and codeine is performed by immunoassay. Confirmation is by gas chromatography/mass spectrometry (GC/MS).
Cutoff and Detection Post Dose
The detection limit of the initial screen is 300 ng/ml, with a sensitivity of 20 ng/ml. This is sufficient to detect heroin use for approximately 24-48 hours post dose and codeine for somewhat longer. Positives are confirmed on GC/MS at a cutoff level of 300 ng/ml.