Opioid Abuse Clinical Presentation

The Diagnostic and Statistical Manual for Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) defines opioid abuse as a maladaptive pattern of opioid use leading to clinically significant impairment or distress occurring in any of the following areas, within a 12-month period.

• Failure to fulfill major job obligations at work, school, or home
• Recurrent opioid use in hazardous situations, such as driving or operating heavy machines while impaired
• Opioid-related legal problems
• Social and interpersonal problems caused by or exacerbated by opioid use

Most individuals who meet the criteria of opioid abuse and continue to use eventually meet the criteria of opioid dependence.

The DSM-IV-TR^[8] defines opioid dependence as a syndrome characterized by a maladaptive pattern of opioid use, leading to clinically significant impairment or distress, as manifested by at least 3 of the following and occurring in a 12-month period.

• Tolerance (see definition below)
• Withdrawal (see definition below)
• Opioids taken in larger amounts or for longer periods than intended
• Persistent desire or unsuccessful efforts to cut down or control opioid use
• A significant amount of time is spent in activities to obtain opioids
• Important social, occupational, or recreational activities are given up or reduced
• Continued opioid use despite knowledge of having a persistent or recurrent physical or psychological problem

Tolerance and withdrawal may or may not be associated with dependence.

The World Health Organization (WHO) defines drug dependence as a syndrome in which the use of a drug or class of drugs takes much higher priority for a given person than behaviors that once had higher value. A decrease in volitional control over the use of opioid drugs is the central part of the behavioral symptoms observed in opioid dependence.

Tolerance

Tolerance is the need for increasing doses of medication to achieve the initial effect of the drug. Tolerance to the analgesic and euphoriant effects and unwanted adverse effects, such as respiratory depression, sedation, and nausea, may develop. However, little tolerance develops to constipation and meiosis. Opioid tolerance usually does not develop in patients with cancer who are being treated for pain; the need for increasing doses in those patients typically is due to an increasing level of pain. No consistent relationship between intrinsic efficacy and tolerance exists.

Withdrawal

Continuous administration of opioids leads to physical dependence, the emergence of withdrawal symptoms during abstinence. Physical dependence is expected after 2-10 days of continuous use when the drug is stopped abruptly. The onset and duration of withdrawal varies with the drug used. For example, meperidine withdrawal symptoms peak in 8-12 hours and last for 4-5 days. Heroin withdrawal symptoms usually peak within 36-72 hours and may last for 7-14 days. Symptoms of opioid withdrawal include the following:

• Autonomic symptoms - Diarrhea, rhinorrhea, diaphoresis, lacrimation, shivering, nausea, emesis, piloerection (the phrase stopping "cold turkey" refers to piloerection, or "gooseflesh")
• Central nervous system arousal - Sleeplessness, restlessness, tremors
• Pain - Abdominal cramping, bone pains, and diffuse muscle aching
• Craving - For the medication

Addiction

The phenomenon of addiction is seen in a variable number of patients using drugs. Addiction is characterized as a psychological and behavioral syndrome in which the following features are observed:

• Drug craving
• Compulsive use
• Strong tendency to relapse after withdrawal

Addiction must be defined by the observation of maladaptive behaviors, such as adverse consequences due to drug use, loss of control over drug use, and preoccupation with obtaining opioids, rather than pharmacological phenomenon of physiologic dependence, tolerance, and dose escalation. Do not use the term addiction to describe patients who are merely physically dependent. Also, keep in mind that undertreatment in patients with pain may result in a pseudoaddiction, and opioid-seeking behavior may be mistaken for addiction.

Long-acting medications, such as methadone and sustained-release morphine, tend to have slower onset of action, and the rush or high experienced with more rapid-onset medications is not as prominent. Thus, the longer-acting opioids are less likely to be abused.

Dependence

Mental status effects include depression with any or all of its symptoms, such as sleep disturbances, lack of interest, selflessness, suicidal ideation, and poor coping skills.

Physiological effects: Because tolerance to many of the actions of the opioids develops, it is not likely for even a careful observer to notice the effects of opioids. Small-sized pupils may be the only observation because only very mild tolerance develops for miosis. Inflamed nasal mucosa may be seen if heroin is snorted.

Withdrawal

Mental status effects include purposive behaviors, such as complaints and manipulations directed at getting more drug, and anxiety.

Physiologic effects include autonomic signs (eg, tachycardia, high blood pressure, fever, piloerection [goose flesh], mydriasis, and lacrimation, CNS arousal (irritability), and yawning.

In milder abstinence syndrome, clinical features may be limited to dysphoria, craving, yawning, lacrimation, rhinorrhea, and restlessness. In moderate-to-severe cases, piloerection, mydriasis, increased BP and pulse, and GI symptoms are seen as well.

Intoxication

Mental status effects include euphoria, sedation, decreased anxiety, a sense of tranquility, and indifference to pain produced by mild-to-moderate intoxication. Severe intoxication can lead to delirium and coma.

Physiological effects include the following:

• Respiratory depression (may occur while the patient maintains consciousness)
• Alterations in temperature regulations
• Hypovolemia (true as well as relative), leading to hypotension
• Miosis
• Needle marks or soft tissue infection
• Increase sphincter tone (can lead to urinary retention)

Addiction

The physical examination provides little information to add in the diagnosis of addiction. However, symptoms of opioid withdrawal and track marks are suggestive of addiction.

Constipation is a common occurrence due to almost continuous use of narcotics.

Opioid dependence is considered a biopsychosocial disorder. Pharmacological, social, genetic, and psychodynamic factors interact to influence abuse behaviors associated with drugs. However, pharmacological factors can be especially prominent, more so than in other types of drug use disorders.

Pharmacological factors

Opioids are strongly reinforcing agents because of the euphoric effects and reported ability to reduce anxiety, increase self esteem, and help coping with daily problems. Most opioids associated with abuse and dependence are mu-agonists, such as heroin, morphine, hydrocodone, oxycodone, and meperidine. Some partial mu-agonists, such as buprenorphine, or some that have no mu-agonism, such as pentazocine, also can possess reinforcing properties. Rapid development of physical dependence and a protracted abstinence syndrome are unique to opioid use and can make abstinence difficult.

Of note, more than half of persons taking 90 days of opioid therapy over a 6-month period remain on opioids years later. Opioid continuation was strongly associated with prior opioid exposure, daily opioid doses of 120 mg or more of morphine equivalent per day, and possible misuse; however the data from which these associations did not include clinical measures of pain or disease severity.^[9]

Social factors

Easy drug availability and acceptable social attitudes make experimentation easy. A high rate of drug use is seen in areas of the city with poor parental functioning and higher crime and unemployment rates. Except for the association between higher exposure to the drug and higher rates of addiction, the precise role of social factors in creating dependent and addictive behaviors is uncertain. Of US service personnel in Vietnam between 1970 and 1972, 42% tried heroin; one half of those personnel became physically dependent, but very few continued to use heroin in their civilian life.

Psychological factors

Ego defects in certain patients are postulated to form the basis of drug use. Opioids are theorized to help the ego in managing painful effects such as anxiety, guilt, and anger. Behavioral theory postulates that basic reward-punishment mechanisms perpetuate addictive behavior

Genetic factors ^[10]

Genetic epidemiologic studies suggest a high degree of heritable vulnerability for opioid dependence. Gene polymorphisms for dopamine receptors/transporters, opioid receptors, serotonin receptors/transporters, proenkephalin, and catechol-O-methyltransferase (COMT) all appear to be associated with vulnerability to opioid dependence. Future interventions for opioid dependence may include medications identified through genetic research.