WHAT OPIATES ARE
Opiate drugs are any drugs, natural or synthetic, that produce the characteristic opiate effects: the combination of a
dreamy, euphoric state; lessened
sensation of pain; slowed breathing; constipation; and pinpoint pupils. Sometimes scientists use the more generic term opioids, which
includes drugs resembling the
substances in the opium poppy as well as endogenous opioids that serve as neurotransmitters in the brain.
Opium refers to a
preparation of the opium
poppy (Papaver somniferum). It is obtained in a very low-tech, labor-intensive
manner throughout the world. Opium farmers cut the developing seedpod of the opium poppy and collect the gummy fluid that oozes
out of the cut over the next few
days. The sap is refined in several ways. It may be dried into a ball and used directly (gum opium) or dried and pounded into a powder (opium powder). Raw opium appears as a brown tarry
substance. Opium can also be made
into an alcohol-water extract called tincture of opium. This is the famous laudanum of your great-great-grandmother's era, or the paregoric of that age.
Morphine, which is one of the mainstays for pain
management, is a major constituent of
the seedpod. It is a potent opiate and is used in injectable or pill form to relieve pain after
surgery and for extreme pain, such as
in advanced cancer. Codeine is a much less potent opiate that is
Heroin is a chemically modified form of morphine
that is created from partially
purified morphine, usually in "refineries" close to sites of opium production. It is broken up into small amounts and
usually appears on the street in bags
of loose powder containing about one hundred milligrams. The actual color can
range from white to brown to black depending upon the source and quality of the preparation
technique. Highly purified heroin
hydrochloride is a white powder that is prized for its purity, while Mexican "black tar" heroin at the other
end of the spectrum is recognized by
its black appearance. 'The user either snorts the powder directly or dissolves it in saline and injects it. The actual composition
of the powder depends upon the
supplier and can range from 10 to 70 percent heroin (in combination) with various contaminants, including
talc, quinine, and baking powder,
making up the balance.
Opium poppies grown in Southeast Asia (Burma and
Thailand), Afghanistan, South America
(Colombia), and Mexico provide the starting material for illegal heroin that enters the United States. Southeast
Asian poppies mostly provide heroin for Europe, although some makes its way to the United States. Heroin production
from Afghanistan still represents the majority of worldwide production (tenfold
more than the next highest supplier,
which is Mexico), but heroin in the United States mainly comes from South America (East Coast) or
from Mexico (West Coast) (US
Department of Justice National Drug Intelligence Center, Threat Assessment 2011).
The purity of heroin
varies widely. In the most recent report from the DEA (from 2011), the average purity in the United
States was 30 percent, with ranges
from 5 percent to 66 percent, depending upon the location. If heroin is just morphine that has been slightly
changed chemically, what advantage
does it have? In fact, once heroin enters the brain, it is converted back to
morphine. However, the improved fat solubility does serve a useful purpose—it gets heroin into the brain
faster. Many physicians are lobbying
for its use in terminal cancer patients, as this difference means
faster pain relief The government is weighing the
balance between this medical benefit
and heroin's long and unpopular legal history.
Scientists have made many derivatives of morphine.
the original hope was to find a drug that would eliminate pain but not cause
tolerance or addiction. That mission
has been unsuccessful—all of the effective opiate analgesic drugs are also addictive. However, the
attempt has led to many man-made
opiates with desirable characteristics for particular clinical uses. There are at least five important opiate
analgesics that are either direct
products of the seedpod of the opium poppy or minor modifications of it. These chemically modified drugs are
widely used in medicine, and prescription opiate abuse is a major health
concern today. Ten times more people
abuse prescription opiates than abuse heroin, and rates have increased dramatically in the last ten years, as
have overdose deaths from these drugs. Therefore, we will spend some time
describing them in detail.
Some of the
most widely used and abused prescription narcotics are modifications of morphine. These are hydromorphone,
oxycodone, and hydrocodone.
Hydromorphone (Dilaudid), a very strong opiate, is an effective analgesic that is widely abused. Oxycodone is
synthesized from a nonanalgesic in opium (thebaine) and ranks between morphine
and codeine in its effectiveness
against pain. Its use has spread dramatically in the United States in the last few years, due in part to its
appropriate use to treat pain. It is
also marketed in combination with aspirin under the prescription name Percodan. Hydrocodone (Vicodin) is a moderately
strong opiate that is also widely
abused.
Meperidine (Demerol) is used like morphine for intense postsurgical pain, but
it works well even with oral use. Meperichne has a definite downside:
it can cause seizures at high doses--a feature that has led to decreased
use by physicians in recent years. Methadone is a long-lasting opiate that is
taken as a pill. Its unique time course makes it particularly useful
for replacement therapy for treating opiate addiction as well as chronic
pain. The gradual and mild onset of action staves off withdrawal signs but
doesn't provide a "high." Its use for these purposes is controversial in
some circles: although tolerance and physical dependence clearly develop, it
provides safe and effective treatment without the same liability for
abuse. One important characteristic of methadone is its very long halflife—it
remains in the body for hours. This is a helpful characteristic in suppressing
opiate withdrawal and in treating chronic pain. However, it also
represents a danger to people who do not follow instructions about its use.
Overdose deaths from methadone have increased 800 percent in the last five to
ten years. Most of these deaths have occurred in people who were using it for pain relief, not abusing it.
Fentanyl (Sublimaze) and its relatives are very fat-soluble,
very fast-acting analgesics that anesthesiologists
use when they put patients to sleep. Fentanyl is also used in patches that
release the drug slowly through the skin to provide more long-lasting pain relief. Its most unusual
formulation is a lollipop designed to
deliver the drug to young children before surgery. Many addicts use fentanyl in its injectable form, and
it is a common cause of overdose.
Fentanyl's high comes on fast and is intense, brief, and just a step away from fatal suppression of breathing.
Finally, there is propoxyphene
(Darvon). This drug is such a poor opiate that most physicians won't use
it, because clinical studies find it to be no more effective than a placebo. However, some people swear by it,
although it's really little stronger
than aspirin.
All the opiate drugs bind to the same molecule in the
brain, but they do so with varying
degrees of success. What follows is a list of drugs that bind very well, bind okay, and bind poorly. The clinical
use of these drugs is determined in
large part by this quality. Obviously, a drug like codeine won't do much good with the pain caused by major
abdominal surgery, and hydromorphone
would be overdoing it for a simple headache. Therefore, the form in which each
of these is prepared and administered is tailored to its typical use.
OPIATE
DRUGS
High
Efficacy Medium
Efficacy Low
Efficacy
morphine hydrocodone codeine
hydromorphone oxycodone propoxyphene
meperidine
fentanyl
