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Chapter 10   Opiates
 

Chapter 10 Opiates

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    Chapter 10   Opiates Chapter 10 Opiates Presentation Transcript

    • Opiates Chapter 10
    • Introduction
      • It has already been established that psychoactive drugs can be double-edged swords in their potential for improving the human condition on the one hand, and their capacity to cause destruction to individuals and society on the other.
      • No group of drugs captures this paradox more dramatically than the class of drugs we call the opiates – opium, morphine, heroin, and related compounds
      • Opiate drugs have been used for centuries to relieve pain and when first introduced in Europe, were hailed as a godsend
      • Even today opiate drugs remain the most potent pain killers available to physicians, yet we now recognize the other edge of the opiate sword – their ability to produce severe dependence
      • Heroin is viewed as the prototype addictive drug and illegal use and traffic in heroin are major international problems
    • History of the Opiates
      • Opium comes from a species of the poppy plant
      • Opium – The dried sap produced by the seed pod of the poppy plant. A person experiences the effects of opium by consuming this substance orally or smoking it
      • Opium has been used for medicinal purposes for over 6,000 years due to its analgesic (pain-relieving), cough-suppressant, and antidiarrhea properties
      • Analgesia – Pain relief produced without a loss of consciousness
      • In 1803, the major active ingredient in opium, morphine was isolated.
      • Morphine was 10 times more potent than crude opium and the pharmacist who developed it was so impressed with the blissful, dreamlike state it produced, he named it after Morpheus, the Greek God of dreams
      • Codeine is another opiate drug found in opium
      • With the development of the hypodermic syringe in the mid-1800s, morphine became a major dependence problem in Europe and the U.S.
      • In the late 1800s, heroin was developed and was found to be twice as potent as morphine. Heroin was initially viewed as an alternative to morphine, and with its greater potency, was said to have “heroic” possibilities. It was thus christened heroin.
      • Heroin – A drug produced by chemically processing morphine. It is more potent than morphine and has become the major opiate drug of abuse
      • Initially used as a cough suppressant and pain reliever
      • In an effort to address the opiate dependence problem, the Harrison Narcotic Act was passed in 1914 placing control of opiate drugs in the hands of physicians. However, legislative interpretations ruled that physicians must not prescribe opiates unless:
        • Doses could be shown to be decreasing over time
        • They did not prescribe to addicts, and
        • Heroin must not be prescribed at all
      • The Harrison Narcotic Act marked the beginning of drug crime in America and changed the type of person who became or remained addicted to opiates
      • Before the Harrison Act, opiate addiction cut across social classes with a wealthy middle-aged woman as likely to be an opiate addict as anyone
      • After the Harrison Act, and as heroin emerged as the addict’s drug of choice, addicts tended to be more and more young, poorly educated men of lower socioeconomic status
    • Opiate Use in the 20 th Century and Today
      • Most heroin is produced in Southwest Asia (Afghanistan and Pakistan), the “golden triangle” of Southeast Asia (Laos, Myanmar, and Thailand), and South and Central America – mostly Columbia and Mexico
      • Opium and heroin production has been declining in Southeast Asia only to be offset by rising production in Afghanistan, which is now producing 87% of the world’s opium/heroin.
      • Afghan President urged his people in 2004 to declare holy war on drug production, yet opium farming still accounts for nearly half of the domestic economy.
      • Heroin use increased dramatically in the United States throughout the 1990s and continues to rise in the 2000s. It is also made inroads in other populations
      • Heroin casualties in recent years included John Belushi (heroin and cocaine), Layne Staley, lead singer and guitarist for Alice in Chains, Jerry Garcia of the Grateful Dead (poor health due to yrs of heroin addiction), and Kurt Cobain (heroin-related)suicide
      • The National Institute on Drug Abuse estimates that heroin overdose is responsible for more than 1,000 deaths every year
    • Designer Heroin
      • Produced illicitly by chemists who develop chemical analogues to heroin
      • Most designer heroin compounds are derivatives of the powerful opioid, fentanyl and may be 10 to 1,000 times more potent than heroin (100 times more potent than Morphine). Thus the risk of overdose is greater
      • MPTP is a highly toxic compound accidentally produced when trying to make the designer heroin drug MPPP. It selectively attacks and rapidly destroys the substantia nigra, which leads to symptoms of advanced Parkinson’s disease
    • Prescription Opiate Abuse
      • Explosive increase in prescription opiate drugs
      • Illicit use of prescription opiates more than tripled from 1990-2005 and the most publicized drug included has been Oxycontin (Oxycodone)
      • Oxycodone has been on the market for decades in other prescription pain killers, i.e., Percodan, but in much lower doses (5 milligrams)
      • Oxycontin initially ranged from 20-160 milligrams in time-release form so it could last up to 12 hours.
      • Illicit users discovered they could crush and snort or inject the drug delivering a much larger dose all at once making it particularly dangerous
      • In 2001, as a result of DEA pressure Purdue Pharma discontinued the 160 milligram dose but continues to market 20-40-80mg tablets.
      • Though other illicit drug use is down for young people, use of Oxycontin and other prescription opiates rose dramatically from 1991-2005
      • Diversion of prescription opiate drugs has become a significant national problem
    • Pharmacokinetics
      • Opiate drugs may be taken into the body in a variety of ways. Though they are readily absorbed from the gastrointestinal tract, most are smoked, inhaled, or injected for greater effect
      • Main difference between morphine and heroin is that heroin is more lipid-soluble and thus more readily penetrates the blood-brain barrier. Once in the brain, heroin is converted to morphine
      • Opiates are rapidly metabolized with 90% excretion within a day after taking the drug
      • Traces may remain in the urine for two to four days after use
    • Mechanisms of Opiate Action
      • Opiate drugs act in the brain by mimicking endorphins, natural neurotransmitters that are involved in the regulation of pain
      • Beta-endorphin, enkephalin, and dynorphin are the most important compounds
      • Naloxone (Narcane) – A short-acting opiate antagonist that reverses or blocks the effects of morphine and other opiate drugs
      • It was the discovery of naloxone in the 1960s that prompted researchers to look for and discover “opiate receptors” in the brain and the endorphins
    • Medical Use of Opiate Drugs
      • Major medical use of opiate drugs is for their analgesic or pain-relieving effects
      • See Table 10.1 for a Comparison of the Major Opiate Drugs and their potency relative to a dose of morphine
      • Heroin, though more potent than morphine, is not administered by doctors in the United States
      • A preparation called Brompton’s cocktail, composed of heroin and cocaine, is administered to the terminally ill in Great Britain
      • Should physicians be allowed to administer it here ? If so, when ?
      • Illicit use of prescription opiates more than tripled from the early 1990s to 2005, and the most publicized drug included in the increase has been Oxycontin
      • Oxycontin – Designed to treat severe and chronic pain, contains a higher dose and longer duration of action than its generic oxycodone that has been on the market in Percodan for years.
      • The synthetic opiate drug dextromethorphan has no analgesic or addictive properties but is commonly used as a cough suppressant
    • CONTEMPORARY ISSUE BOX 10.3 “Ultra-low Dose Naltrexone and NMDA Antagonists: New Approaches to Make Prescription Opiates Safer
      • Counter problems associated with use and misuse of opiate drugs by combining a prescription opiate pain killer with an opiate antagonist such as Naltrexone. If dose of Naltrexone is low enough, it can enhance the pain-relieving effects of the opiate agonist but still block the rewarding effects of the drug, retard the development of tolerance, and lesson withdrawal severity. Such results have been reported in nonhuman experiments and studies with osteoarthritis patients taking Oxycontin and Naltrexone have been promising.
      • Development of such compounds will increase the safety of pain medication and lesson the problem of diversion and abuse.
    • Acute Psychological and Physiological Effects of Opiates
      • Subjective reports of the opiate euphoria include drowsiness, body warmth, floating sensation, and a heavy feeling of the limbs
      • Vivid dreamlike experiences are reported, thus the expression “pipe dreams”
      • There is good evidence that opiate drugs reduce sexual desire or interest, and in men often produce impotence
      • Nausea and vomiting often occur immediately after taking opiates
      • Causes constriction of the pupils and “pinpoint pupils” suggest opiate poisoning
      • Like depressants, opiates cause respiratory depression and lowered body temperature
      • When a high dose of heroin is fatal, the immediate cause is usually respiratory failure
      • Most heroin overdose cases, however, usually involve a lethal drug interaction between heroin and alcohol or another depressant drug
      • Opiates and depressant drugs potentiate one another and this synergy can often be fatal, i.e., Janis Joplin (heroin and alcohol)
    • Chronic Effects of Opiates
      • Regular use of opiates results in tolerance and an abstinence syndrome characterized by flu-like symptoms and intense drug craving
      • Withdrawal begins 8 to 12 hours after the last dose and symptoms continue to worsen and reach a peak after 48 to 78 hours
      • One common symptom, goosebumps, is said to leave the addict looking like a plucked turkey and may be the basis for the expression “cold turkey”
      • Spastic movements of the arms and legs may appear like kicking and thus the term “kicking the habit”
      • Low doses of synthetic drugs such as methadone are often used in detoxification programs to reduce the severity of the withdrawal symptoms and then gradually tapered off until the physical dependence is gone
      • There is an estimated relapse rate of 90% within two years of leaving treatment centers, illustrating heroin addiction is more complex than simple avoidance of withdrawal symptoms
    • It’s test time again ! Time to study !