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  • Psychic dependence (addiction): craving, drug-seeking

  • Physical dependence: somatic withdrawal symptoms and signs

  • Drug-specific symptoms and signs

  • Medical and neurologic complications

Drug dependence is of two types. Psychic dependence leads to craving and drug-seeking behavior. Physical dependence produces somatic withdrawal symptoms and signs. Psychic and physical dependence can coexist or occur alone. Addiction is psychic dependence.

Tolerance refers to the need for ever higher doses of a drug to achieve the desired effect. Sensitization (“reverse tolerance”) refers to increased drug effects (including craving) with repeated administration.

Worldwide hundreds of different agents are used recreationally for their psychic properties. Broad categories of agents popular in North America and Europe are listed in Table 34–1. These agents differ in their addiction liability; in the symptoms and signs associated with intoxication, overdose, and withdrawal; and in the medical and neurological complications that sometimes follow their use.

Table 34–1.Categories of drug dependence.



Opioids include agonists, antagonists, and mixed agonist-antagonists (Table 34–2). At intended levels of intoxication, opioid agonists produce drowsy euphoria, miosis, analgesia, cough suppression, and often nausea, vomiting, pruritus, hypothermia, postural hypotension, constipation, and decreased libido. Parenteral or smoked heroin (the most widely abused opioid) produces a “rush”—a brief ecstatic feeling followed by euphoria and either relaxed “nodding” or garrulous hyperactivity.

Table 34–2.Opioids currently or recently available in the United States.

In the past two decades, there has been a worldwide surge in prescribing opioid drugs for chronic pain, resulting in an epidemic of recreational use of both prescription opioids and illicit opioids, especially heroin and fentanyl analogs. In the United States during 2016, opioid overdose resulted in more than 58,000 deaths (fentanyl and analogs 20,100; heroin 15,400; prescription opioids 14,400), a 22% increase over the previous year.

Overdose ...

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