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Opium
There were no
legal restrictions on the importation or use of opium until the
early 1900s. In the United States, the unrestricted availability
of opium, the influx of opium-smoking immigrants from East Asia,
and the invention of the hypodermic needle contributed to the
more severe variety of compulsive drug abuse seen at the turn of
the 20th century. In those days, medicines often contained opium
without any warning label. Today, there are state, federal, and
international laws governing the production and distribution of
narcotic substances.
Although opium
is used in the form of paragoric to treat diarrhea, most opium
imported into the United States is broken down into its alkaloid
constituents. These alkaloids are divided into two distinct
chemical classes, phenanthrenes and isoquinolines. The principal
phenanthrenes are morphine, codeine, and thebaine, while the
isoquinolines have no significant central nervous system effects
and are not regulated under the CSA.
Detection of Opiates in Urine
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.
Pharmacological
Properties
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 Methods
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.
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