Opioids

Learning Objectives

  • Identify opioids and describe how they impact the brain and behavior

An opioid is one of a category of drugs that includes heroin, morphine, methadone, and codeine. Opioids have analgesic properties; that is, they decrease pain. Humans have an endogenous opioid neurotransmitter system—the body makes small quantities of opioid compounds that bind to opioid receptors reducing pain and producing euphoria. Thus, opioid drugs, which mimic this endogenous painkilling mechanism, have an extremely high potential for abuse. Natural opioids, called opiates, are derivatives of opium, which is a naturally occurring compound found in the poppy plant. There are now several synthetic versions of opiate drugs (correctly called opioids) that have very potent painkilling effects, and they are often abused. For example, the National Institutes of Drug Abuse has sponsored research that suggests the misuse and abuse of the prescription pain killers hydrocodone and oxycodone are significant public health concerns (Maxwell, 2006). In 2013, the U.S. Food and Drug Administration recommended tighter controls on their medical use.

Historically, heroin has been a major opioid drug of abuse (Figure 1). Heroin can be snorted, smoked, or injected intravenously. Like the stimulants described earlier, the use of heroin is associated with an initial feeling of euphoria followed by periods of agitation. Because heroin is often administered via intravenous injection, users often bear needle track marks on their arms and, like all abusers of intravenous drugs, have an increased risk for contraction of both tuberculosis and HIV.

Photograph A shows various paraphernalia spread out on a black surface. The items include a tourniquet, three syringes of varying widths, three cotton-balls, a tiny cooking vessel, a condom, a capsule of sterile water, and an alcohol swab. Photograph B shows a hand holding a spoon containing heroin tar above a small candle.

Figure 1. (a) Common paraphernalia for heroin preparation and use are shown here in a needle exchange kit. (b) Heroin is cooked on a spoon over a candle. (credit a: modification of work by Todd Huffman)

Aside from their utility as analgesic drugs, opioid-like compounds are often found in cough suppressants, anti-nausea, and anti-diarrhea medications. Given that withdrawal from a drug often involves an experience opposite to the effect of the drug, it should be no surprise that opioid withdrawal resembles a severe case of the flu. While opioid withdrawal can be extremely unpleasant, it is not life-threatening (Julien, 2005). Still, people experiencing opioid withdrawal may be given methadone to make withdrawal from the drug less difficult. Methadone is a synthetic opioid that is less euphorigenic than heroin and similar drugs. Methadone clinics help people who previously struggled with opioid addiction manage withdrawal symptoms through the use of methadone. Other drugs, including the opioid buprenorphine, have also been used to alleviate symptoms of opiate withdrawal.

Codeine is an opioid with relatively low potency. It is often prescribed for minor pain, and it is available over-the-counter in some other countries. Like all opioids, codeine does have abuse potential. In fact, abuse of prescription opioid medications is becoming a major concern worldwide (Aquina, Marques-Baptista, Bridgeman, & Merlin, 2009; Casati, Sedefov, & Pfeiffer-Gerschel, 2012).

The Opioid Epidemic

The opioid epidemic, or the opioid crisis, refers to the extensive overuse of opioid drugs, both from medical prescriptions and from illegal sources. The epidemic began slowly in the United States, beginning in the late 1990s, and led to a massive increase in opioid use in recent years, contributing to over 70,000 drug overdose deaths in the U.S. in 2018. Fentanyl alone, being 50 times stronger than heroin and 100 times stronger than morphine, was causing about 200 overdose deaths per day in 2017.[1]

Opioids are a diverse class of moderately strong, addictive, inexpensive painkillers prescribed by doctors. In the late 1990s, pharmaceutical companies reassured the medical community that patients would not become addicted to opioid pain relievers and healthcare providers began to prescribe them at greater rates. This led to widespread misuse of both prescription and non-prescription opioids before it became clear that these medications could indeed be highly addictive.

Though aggressive opioid prescription practices played the biggest role in creating the epidemic, the popularity of illegal substances such as potent heroin and illicit fentanyl have become an increasingly large factor. It has been suggested that decreased supply of prescription opioids caused by opioid prescribing reforms turned people who were already addicted to opioids towards illegal substances.[2]

In 2015, approximately 50% of drug overdoses were not the result of an opioid product from a prescription, though most abusers’ first exposure had still been by lawful prescription.[3] By 2018, another study suggested that 75% of opioid abusers started their opioid use by taking drugs which had been obtained in a way other than by legitimate prescription.[4]

Those addicted to opioids, both legal and illegal, are increasingly young, white, and female, with 1.2 million women addicted compared to 0.9 million men in 2015. The populations of rural areas of the country have been the hardest hit. Teen abuse of opioids has been noticeably increasing since 2006, using prescription drugs more than any illicit drug except marijuana; more than cocaine, heroin, and methamphetamine combined. The crisis has also changed moral, social, and cultural resistance to street drug alternatives such as heroin.

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Glossary

codeine: opiate with relatively low potency often prescribed for minor pain
methadone: synthetic opioid that is less euphorogenic than heroin and similar drugs; used to manage withdrawal symptoms in opiate users
methadone clinic: uses methadone to treat withdrawal symptoms in opiate users
methamphetamine: type of amphetamine that can be made from pseudoephedrine, an over-the-counter drug; widely manufactured and abused
opiate/opioid: one of a category of drugs that has strong analgesic properties; opiates are produced from the resin of the opium poppy; includes heroin, morphine, methadone, and codeine

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  1. Fentanyl As A Dark Web Profit Center, From Chinese Labs To U.S. Streets", KUAR, NPR Radio News, Sept. 4, 2019
  2. Prescription Opioid Data". Centers for Disease Control and Prevention (CDC). Retrieved November 2, 2018.
  3. Shipton EA, Shipton EE, Shipton AJ (June 2018). "A Review of the Opioid Epidemic: What Do We Do About It?"Pain and Therapy7 (1): 23–36.
  4. Pergolizzi JV, LeQuang JA, Taylor R, Raffa RB (January 2018). "Going beyond prescription pain relievers to understand the opioid epidemic: the role of illicit fentanyl, new psychoactive substances, and street heroin". Postgraduate Medicine130 (1): 1–8.