Opioid use Disorders

Opiates include morphine, heroin, codeine, meperidine, and hydromorphone. Heroin is only available illegally in the United States. Opiates are commonly used for pain control.

Epidemiology

Opiate use and abuse are relatively uncommon in the United States. Lifetime prevalence in 1991 was 0.9% and point prevalence was less than 0.1 %, although more recent surveys indicate opiate use and abuse has been increasing during the past decade. Many of those who use opiates recreationally become addicted. The number of opiate addicts in the United States is estimated at 500,000.

Clinical Manifestations

History, Physical and Mental Status Examinations, and Laboratory Tests Most heroin and morphine users take opiates intravenously, which produces flushing and an intensely pleasurable, diffuse bodily sensation that resembles orgasm. This initial "rush" is followed by a sense of well-being. Psychomotor retardation, drowsiness, inactivity, and impaired concentration ensue. Signs of intoxication occur immediately after the addict "shoots up" and include pupillary constriction, respiratory depression, slurred speech, hypotension, bradycardia, and hypothermia. Nausea, vomiting, and constipation are common after opiate use. Opiate use can be confirmed by urine or serum toxicologic measurements.

Opiate abuse is defined by the criteria for substance abuse noted above. In opiate dependence, tolerance to the effects of opiates occurs. Addicts "shoot up" three or more times per day.

Withdrawal symptoms usually begin 10 hours after the last dose. Withdrawal from opiates can be highly uncomfortable but is rarely medically complicated or life-threatening. Withdrawal symptoms are listed in Table 5-2.

Opiate addicts often have comorbid substance use disorders, antisocial or borderline personality disorders, and mood disorders. Opiate addicts are more prone to commit crimes because of the high cost of opiates. Opiate addiction also is associated with high mortality rates from inadvertent overdoses, accidents, and suicide. Opiate addicts are also at higher risk of medical problems because of poor nutrition and use of dirty needles. Common medical disorders include serum hepatitis, HIV infection, endocarditis, pneumonia, and cellulitis.

Differential Diagnosis

The diagnosis of opiate addiction is usually obvious after a careful history and mental status and physical examinations.

Management

Patients addicted to opiates should be gradually withdrawn using methadone. Methadone is a weak agonist of the mu opiate receptor and has a longer half-life (15 hours) than heroin or morphine. Thus, it causes relatively few intoxicant or withdrawal effects. Generally, the initial dose of methadone (typically 5-20mg) is based on the profile of withdrawal symptoms. Withdrawal from short-acting opiates lasts 7 to 10 days; withdrawal from longer-acting meperidine lasts 2 to 3 weeks.