Opioid intoxication is characterized by maladaptive and clinically significant behavioral changes developing within minutes to a few hours after opioid use (see DSM-IV-TR for substance intoxication on general approaches to substance abuse disorder. Symp-toms include an initial euphoria sometimes followed by dysphoria or apathy. Psychomotor retardation or agitation, impaired judgment, and impaired social or occupational functioning are commonly seen. Intoxication is accompanied by pupillary constriction unless there has been a severe overdose with consequent anoxia and pupillary dilatation. Persons with intoxication are often drowsy (described as being “on the nod”) or even obtunded, have slurred speech, im-paired memory and demonstrate inattention to the environment to the point of ignoring potentially harmful events. Dryness of secre-tions in the mouth and nose, slowing of gastrointestinal activity and constipation are associated with both acute and chronic opioid use. Visual acuity may be impaired as a result of pupillary constriction. The magnitude of the behavioral and physiologic changes depends on the dose as well as individual characteristics of the user such as rate of absorption, chronicity of use and tolerance. Symptoms of opioid intoxication usually last for several hours, but are dependent on the half-life of the particular opioid that has been used. Severe intoxication following an opioid overdose can lead to coma, respira-tory depression, pupillary dilatation, unconsciousness and death.
Opioid withdrawal is a clinically significant, maladaptive behav-ioral and physiological syndrome associated with cessation or re-duction of opioid use that has been heavy and prolonged (see DSM-IV-TR criteria for substance withdrawal from general approaches to substance abuse disorders p. 410. It can also be precipitated by administration of an opioid antagonist such as naloxone or naltrex-one. Patients in opioid withdrawal typically demonstrate a pattern of signs and symptoms that are opposite the acute agonist effects. The first of these are subjective and consist of complaints of anxiety, rest-lessness and an “achy feeling” that is often located in the back and legs. These symptoms are accompanied by a wish to obtain opioids (sometimes called “craving”) and drug-seeking behavior, along with irritability and increased sensitivity to pain. Additionally, patients typically demonstrate three or more of the following: dysphoric or depressed mood; nausea or vomiting; diarrhea; muscle aches; lacri-mation or rhinorrhea; increased sweating; yawning; fever; insomnia; pupillary dilatation; fever; and piloerection. Piloerection and with-drawal-related fever are rarely seen in clinical settings (other than prison) as they are signs of advanced withdrawal in persons with a very significant degree of physiologic dependence; opioid-dependent persons with “habits” of that magnitude usually manage to obtain drugs before withdrawal becomes so faradvanced. For short act-ing drugs such as heroin, withdrawal symptoms occur within 6 to 24 hours after the last dose in most dependent persons, peak within 1 to 3 days and gradually subside over a period of 5 to 7 days. Symp-toms may take 2 to 4 days to emerge in the case of longer acting drugs such as methadone or levo-alpha-acetylmethadol (LAAM). Less acute withdrawal symptoms are sometimes present and can last for weeks to months. These more persistent symptoms can include anxiety, dysphoria, anhedonia, insomnia and drug craving.
Opioid dependence is diagnosed by the signs and symptoms associated with compulsive, prolonged self-administration of opioids which are used for no legitimate medical purpose, or if a medical condition exists that requires opioid treatment, are used in doses that greatly exceed the amount needed for pain relief. Persons with opioid dependence typically demonstrate continued use in spite of adverse physical, behavioral and psychological consequences. Almost all persons meeting criteria for opioid de-pendence have significant levels of tolerance and will experience withdrawal upon abrupt discontinuation of opioid drugs. Persons with opioid dependence tend to develop such regular patterns of compulsive use that daily activities are typically planned around obtaining and administering drugs.
Opioids are usually purchased on the illicit market, but they can also be obtained by forging prescriptions, faking or ex-aggerating medical problems, or by receiving simultaneous pre-scriptions from several physicians. Physicians and other health care professionals who are dependent will often obtain opioids by writing prescriptions or by diverting opioids that have been prescribed for their own patients.
Opioid abuse is a maladaptive pattern of intermittent use in haz-ardous situations (driving under the influence, being intoxicated while using heavy machinery, working in dangerous places, etc.), or periodic use resulting in adverse social, legal, or interpersonal problems (see DSM-IV-TR criteria on p. 409). All of these signs and symptoms can also be seen in persons who are dependent; abuse is characterized by less regular use than dependence (i.e., compulsive use not present) and by the absence of significant tolerance or withdrawal. As with other substance use disorders, opioid abuse and dependence are hierarchical and thus persons diagnosed as having opioid abuse must never have met criteria for opioid dependence.