Opiates
(Ch. 15)
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OPIUM: A HISTORICAL
PERSPECTIVE
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Opium comes from
the plant Papaver somniferum
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Opium is produced
and available for collection for only a few days of the plant's life, between
the time the petals drop and before the seed pod matures. Today, as before,
opium harvesters move through the fields in the early evening and use a
sharp clawed tool to make shallow cuts into the unripe seed pod. During
the night a white substance oozes from the cuts, oxidizes to a gummy, red-brown
colored resinous substance. In the morning this substance is carefully
scraped from the pod and collected in small balls. This raw opium forms
the basis for the opium medicines used throughout history and is the substance
from which morphine is extracted and then heroin is derived
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Early Egyptians
and Greeks (1500 BC) are believed to have used opium, socially and medicinally
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In Arabia, opium
use was common because the Koran forbade alcohol use
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Opium and hashish
became the primary social drug wherever the Islamic culture moved
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Opium was later
introduced into India, China and Europe
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The English writer
Thomas De Quincey glorified opium in the early 1800’s
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THE OPIUM WARS
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One reason opium
smoking was popularized in China was because of the ban on tobacco smoking
in 1644. At first, opium was mixed with tobacco and took the edge off of
the craving for tobacco - the amount of tobacco used was gradually reduced
and then omitted altogether
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In 1729, opium smoking
for nonmedical purposes was outlawed, giving rise to illegal smuggling
from India
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Eventually the British
smuggled in opium for profit through the British East India Company
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When the emperor
of China attempted to suppress the opium smuggling, the Opium War broke
out in 1839 between England and China. Basically, the British went to war
in order to continue bringing opium into China against the wishes of the
Chinese national government. The war lasted for two years
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In 1906, Parliament
supported and passed a bill that eventually ended the opium trade by 1913
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THE DEVELOPMENT
OF OPIUM DERIVATIVES
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Morphine was developed
in 1806 by Frederich Serturner. The active agent was ten times as potent
as opium.
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By 1832 codeine
was developed.
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The major increase
in the use of morphine came as a result of two nondrug developments:
1) the development of the hyperdermic syringe in 1853, and 2) war - The
American Civil War (1861-1865); the Prussian-Austrian War (1866); and the
Franco-Prussian War (1870). Prussia is a former state in N. Europe; it
bacame the foundation for the German empire in the 1870s. Morphine given
by injection worked rapidly and well for the reduction of pain and relief
from dysentary
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Heroin was developed
in the late 1874 by adding two acetyl groups to the morphine molecule,
yeilding diacetylmorphine, which was eventually given the brand name Heroin
and placed on the market in 1898 by Bayer Laboratories
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Heroin is three
times as potent as morphine. The pharmacology of heroin and morphine is
identical except that the two acetyl groups increase the lipid solubility
of the heroin molecule, and thus the molecule enters the brain more rapidly.
The additional groups are then dettached, yielding morphine. Therefore,
the effects of morphine and heroin are identical except that heroin is
more potent and acts faster
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NARCOTIC ADDICTION
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Addiction increased
as a result of opiates in patent medicines (for self-medication), development
of the hypodermic needle, importation of Chinese laborers, and use during
the Civil War
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Medical concern
developed over the number of peole who were addicted to opiates, and this
concern was a part of the motivation that led to the passage of the 1906
Pure Food and Drug Act
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Physicians dispensed
opiates a great deal in their practice and this contributed to high rates
of opiate addiction (~1% of the population at the turn of the century).
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There is plenty
of support for the thesis that between the period 1806-1914, when drugs
were widely used - it was because they met the needs of that culture
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The 1914 Harrison
Act curtailed legal use of narcotics by addicts by limiting access and
eventually eliminating access to addicts
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After the Harrison
Act, addicts were viewed as degenerate, vile individuals rather than as
poor people worthy of sympathy. By 1922, the only source of opiates available
for the nonhospitalized addict was an illegal dealer. Because heroin was
the most potent opiate available, it was the easiest to conceal and therefore
became the illegal dealer's choice. The cost through this source was 30-50
times the price of the same drug through legitimate sources, which no longer
were available to the addict
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After World War
II, heroine use increased in slum areas of large cities; gradually prices
increased, and quality decreased
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In 1961 a critical
shortage of heroin developed and prices tripled - it was this event that
that disrupted the previous social cohesiveness among addicts, increased
the amount of crime, and contributed to the general social disorganzation
of the ghettos, where most addicts lived
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During the Vietnam
conflict early reports (1971) estimated that 10-15% of the American troops
were addicted to heroin. Many of these were thought to be addicts. A follow-up
study released in September 1971 showed that most of the Vietnam heroin
users did not continue heroin use in this country. Only 1-2% were using
narcotics 8-12 months after returning from Vietnam and being released from
the service, approximately the same percentage of individuals found to
be using narcotics when examined for induction into the service.
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Different groups
of researchers estimated the number of heroin addicts from 1970 to the
mid-1980s, and the estimates mostly ranged between 400,000 and 500,000
addicts
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Today, over half
of the heroin supply comes from Southeast Asia (56%), followed by Southwest
Asia and Mexico (~22% each)
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Since the mid-1970s
the quality (purity) of heroin has increased drastically
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PHARMACOLOGY
OF NARCOTICS
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Heroin is capable
of penetrating the blood-brain barrier more easily than morphine, thus
making heroin 2-3 times more potent
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Medicinal chemists
have worked hard to produce compounds that would be effective painkillers,
trying to separate the analgesic effect of theopiates from their depence-producing
effects. Althugh the two efects could not be separated, the research has
resulted in synthetic opiates that are sold as pain releivers.
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Sympathetic narcotics
such as fentanyl and sufentanyl are vastly more potent
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Narcotic antagonists
such as naloxone and naltrexone block the action of narcotics. They may
save a person's life by reversing the depressed respiration resulting from
a narcotic overdose
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Enkephalins and
endorphins are morphine-like substances many times more potent which are
naturally present in the brain. Both of these substances are contained
within neurons and released from terminals to act as neurotransmitters
or as modulators of neural activity.
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These substances,as
well as th natural and synthetic opiate drugs have actions on at least
three different types of opiate receptors, the structures of which
were discovered in the early-1990s. One of the most important sites of
action may be the midbrain central gray are, a region known to be involved
with pain perception. However there are many sites of interaction between
these systems and areas that relate to pain; and pain is a complex psychological
and neurological phenomenon - so we cannot say that we understand completely
how the opiates act to reduce pain. In addition, we know that large amounts
of endorphins are relaeased from the pituitary gland in response to stress.
Also, enkephalins are released from the adrenal gland. The function of
these peptides circulating through the blood as hormones are not understood
at this point
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BENEFITS AND
DRAWBACKS OF NARCOTICS
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The major benefit
of narcotics is that they reduce the emotional response to pain. The effect
of narcotics is relatively specific to pain.
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Relief of diarrhea
(decreasing the number of peristaltic contractions) and suppression of
coughing (decreasing activity in the cough control center in the medulla)
are also achieved by narcotics
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Tolerance to narcotics
occurs although some of the tolerance may be learned (in anticipation of
receiving a dose)
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Physical and psychological
dependency results from prolonged narcotic use
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positive reinforcement
- a behavior is reliably followed by the presentation of a stimulus, leading
to an increase in the probability of the behavior and its eventual maintenance
at a higher rate than before
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negative reinforcement
- an (taking a drug) is followed by the removal of withdrawal symptoms,
leading toi further strengthening of the habit.
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Some narcotic users
are so-called needle freaks who simply like the rush derived from injecting
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Narcotics depress
the respiratory centers in the brain and death can follow if enough narcotics
are used
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Unsterile needles
represent another danger, since hepatitis and HIV can be contracted
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If they survive,
addicts may stop using the drugs because they "mature out"
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Withdrawal symptoms
are not the excruciating experience the media portrays them to be
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New derivatives
are constantly being developed, many with worse consequences than the present
drugs
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THERAPEUTIC APPROACHES
TO NARCOTIC ADDICTION
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Early in the 1930s,
as an answer to prison overpopulation, the US government established treatment
facilities at Lexington, Kentucky, and Fort Worth, Texas
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Narcotic antagonists
such as naltrexon block the effects of narcotics
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Methadone &
L-apha-acetyl methadol (LAAM) maintenance programs substitute methadone
or LAAM (approved for use in 1993) for heroin, preventing withdrawal symptoms
from occurring for up to 24 hours or longer. The theory behind the use
of methadone to help rehabilitate addicts is that the long-lasting effects
of methadone prevent withdrawal symptoms and block the pleasurable effects
of opiates. This could be done in a more controlled environment.
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In Britain addicts
may receive heroin or cocaine or methadone from a specially licensed physician
if the addict is registered as such