Heroin and other opioids: Overview and patient evaluation

Michael F Weaver, MD John A Hopper, MD

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INTRODUCTION — Opiate medications are very effective for the treatment of acute and chronic pain, but also have the potential to be abused. Heroin abuse in the United States (US) has remained at high levels since the mid 1990s, with over 100,000 new users annually [1].

This topic will provide an overview of opioid abuse and patient evaluation. Long-term treatment for opiate dependence is discussed separately. Other substance abuse, and the management of acute intoxication and withdrawal, are also discussed separately. (See "Heroin and other opioids: Management of chronic use", see "Opioid intoxication in adults", see "Opioid withdrawal in the emergency setting", see "Cocaine abuse in adults", see "Sedatives and hypnotics: Clinical use and abuse", see "Marijuana use in adults", see "Designer drugs in adults", and see "Hallucinogen and inhalant abuse in adults").

DEFINITIONS — The term opioid refers to natural and synthetic substances with morphine-like activity. Opiate refers to a subclass of opioids consisting of alkaloid compounds extracted from opium, including morphine, codeine, and semisynthetic derivatives of the poppy plant. The term endorphin refers to another subclass of opioids consisting of endogenous peptides that produce pain relief, including enkephalins, dynorphins, and beta-endorphins.

Opioids have analgesic and central nervous system (CNS) depressant effects, as well as the potential to cause euphoria. Morphine is the prototypical opioid. Heroin is a derivative of morphine and is the opioid most commonly abused by injection.

All opioids activate endogenous opioid receptors. Activation of the mu receptor is responsible for primary opioid effects, including analgesia and euphoria. Mu opioid receptors outside the central nervous system, in smooth muscle of the bronchi and intestines, are responsible for cough suppression and opiate-induced constipation.

Opioid dependence or addiction is defined as continued use of opioids despite significant opioid-induced problems; these problems may be cognitive, behavioral, or physiological [2]. Repeated drug use results in opioid tolerance (requiring escalating doses to achieve the same effect), withdrawal symptoms, and compulsive drug taking.

OPIOID ABUSE — Opium is the crude substance derived from the opium poppy; it has been used by people since as early as 4000 BC. Morphine was purified from opium early in the nineteenth century and widely used for analgesia during the US Civil War. Heroin and morphine were key ingredients in many patent medicines in North America during the late 1800s.

Heroin — The popularity of heroin as a drug of abuse reached a peak in the 1960s, but declined somewhat during the 1970s and 1980s due to greater awareness of the risks of overdose and the increased popularity of cocaine. Throughout the 1990s, heroin abuse again became a growing epidemic. The supply available on the street has become purer and is being tried by more adolescents and middle class people [3]. According to the 1998 National Household Survey on Drug Abuse, an estimated 2.4 million people in the US had used heroin at some point in their lives, and 130,000 reported use in the last month. Data from the 2005 National Survey on Drug Use and Health (NSDUH) are similar, with an estimated 136,000 reporting use of heroin in the past month.

Heroin has a half-life of 30 minutes, but a duration of action of four to five hours due to active metabolites, including morphine [4]. Heroin is metabolized to 6-monoacetylmorphine (6-MAM) [5], a metabolite specific to heroin, detectable on urine testing, and can differentiate heroin from other opioids.

Like all opioids, heroin binds to receptors that are part of endogenous opioid systems [6]. Opioids also act on several other CNS neurotransmitter systems, including dopamine, gamma-amino-butyric acid (GABA), and glutamate. Heroin is more lipid soluble than other opioids, allowing it to rapidly cross the blood-brain barrier (within 15 to 20 seconds) and to reach high brain levels [7].

Names and routes of administration — The chemical name for heroin is diacetylmorphine. Street names include dope, horse, smack, and tar.

Heroin is used by multiple routes of administration.

• Intranasal insufflation (snorting, sniffing) requires minimal equipment and the onset of action is rapid enough to produce euphoria (the "rush"). Increased purity of heroin in the US and concerns over injection risks have resulted in a rising prevalence of heroin snorting in many areas [8].

• The intravenous (IV) route is rapid and potent, but also most dangerous to the user. Injection is the most efficient means of producing euphoria when relatively low purity heroin is being used. Most overdoses occur when heroin is taken intravenously.

• Heroin can be smoked; this is more common in Asian countries where it is known as "chasing the dragon," but has become more popular worldwide, including some cities in the US. Smoking heroin is the fastest route for delivering drug to the brain.

Other opioids — Other opioids besides heroin are subject to abuse. Opium extracted from poppies is more commonly abused outside the US.

The prevalence of prescription opioid abuse in the US has increased in the past decade, and has become one of the fastest growing drug problems [9]. 2005 NSDUH data indicate 2.2 million new non-medical users of prescription analgesics [10]. Most prescription pain medications are illegally diverted from legitimate sources, especially controlled-release oxycodone (OxyContin) and hydrocodone (eg, Vicodin, Lortab) [11]. Health care professionals with access to opioids may personally abuse them, especially meperidine and injectable fentanyl.

Studies have shown differences between those who primarily abuse prescription opioids compared to heroin. Those who abuse prescription opioids:

• are more likely to have complaints of pain [12,13]

• are more likely to be in psychiatric treatment [12]

• have greater social stability [14]

• are less likely to use other illicit drugs [12]

However, up to 2/3 of those who primarily use heroin will also use prescription opioids [11]. Prescription opioids are most commonly obtained from a relative, friend, or dealer, and not directly from a physician.

Overdose — Overdose can occur at any time with any opioid. It is more likely to occur with heroin than prescription opioids because the amount of actual heroin in drugs bought on the street varies from dealer to dealer and day to day, and because of the high lipid solubility of heroin. Tolerance and physical dependence occur after one to two weeks of daily use, resulting in a withdrawal syndrome after abrupt cessation. Tolerance develops much more slowly to the miotic effects, constipation, and respiratory depression. (See "Opioid intoxication in adults").

Detection in drug screens — Metabolites of opioids can be detected on a urine drug screen up to three to four days after the last use and occasionally longer in chronic users (show table 1). Not all opioids are detected on all drug screens because some opioids are broken down to different metabolites for which there are no commonly used screening assays. When evaluating a suspected opioid overdose or withdrawal syndrome, a good history of drugs taken is important in addition to urine drug testing.

False-positive opiate drug screens have been reported in patients taking rifampin and quinolones [15,16] and in those eating poppy seeds (show table 1) [17]. Confirmatory testing (eg, with gas chromatography, mass spectrometry, or high-performance liquid chromatography) is warranted in patients who have a positive screen after ingesting substances which might cause a false positive result, although these techniques may not resolve the issue in the setting of poppy seed consumption. As noted earlier, the presence 6-MAM on confirmatory testing verifies the use of heroin.

Consequences of abuse — Consequences of opioid/heroin addiction and abuse, both to the abuser and to society, are multiple [2]:

• Heroin addiction is associated with increased mortality. In one study, the mortality rate of 115 untreated subjects with heroin addiction was 63 times that expected for a non-using group of the same age and sex distribution, and higher than a group of former heroin users in methadone maintenance programs [18].

• Contaminated drugs and inadequate sterile technique with injection drug use leads to localized and systemic infections (eg, cellulitis, localized abscess at the injection site, endocarditis, osteomyelitis). (See "Skin abscess" and see "Infective endocarditis: Epidemiology and risk factors" and see "Hematogenous osteomyelitis in adults").

• Intravenous drug use with shared needles or syringes is associated with an increased risk of infection with a blood-borne pathogen, such as HIV, hepatitis B, and hepatitis C.

• Hepatitis C virus (HCV) infection may also occur in those who abuse heroin but do not inject it. Transmission has been associated with tattooing [19] and sharing of straws for intranasal insufflation [20,21]. (See "Epidemiology and transmission of hepatitis C virus infection").

• Most impoverished street-level heroin users need to engage in some illegal behavior (ie, shoplifting, burglary, prostitution) to obtain money with which to purchase heroin.

• Health care costs of opioid dependence are over one billion dollars in the US annually [2]. Costs to society include lost work productivity due to intoxication or complications of use, health care costs for uninsured users with medical complications, prosecution and incarceration expenses for criminal offenses, and economic and psychological costs to the victims of crimes. Additional costs arise from transmission of diseases such as HIV and hepatitis to sexual contacts who are not themselves drug users.

HISTORY — Taking a history in a patient who has admitted to use of opioids, most commonly heroin, should focus on the amount of drug used recently, route of administration, last use, previous attempts at drug treatment, and problems that have resulted from drug use. A direct approach is most beneficial; asking these questions as part of a routine health history can improve the comfort of the patient and the clinician. (See "Overview of the recognition and management of the drug abuser", section on History).

Begin by asking how long the patient has been using opioids and the preferred route of administration: intranasal, intravenous, or subcutaneous. Familiarity with street terminology is helpful; intranasal use is often referred to as "snorting" or "sniffing," intravenous use is called "shooting up" or "mainlining," and subcutaneous use is known as "skin-popping."

It is difficult to know exactly how much active drug a patient is using because street drugs are diluted (or "cut") by dealers with other white powders prior to sale. A given amount of heroin powder bought on the street will contain 10 to 40 percent active drug; the rest is an adulterant such as sugar, powdered milk, over-the-counter medications such as aspirin or pseudoephedrine (to counteract some of the drowsiness associated with the high), or even a prescription medication that the dealer has been able to obtain. Heroin becomes progressively more diluted and adulterated as it moves down the distribution chain [22].

Consumer and dealers generally do not know precise measurements of the quantity or potency of the heroin being used or sold [23]. Nevertheless, it is useful to try to estimate the amount of drug being consumed since this will impact the likelihood and severity of withdrawal symptoms when the drug is stopped. It may be helpful to ask the usual amount of drug powder that the addict consumes each time he or she uses and the number of uses per day. Dependent persons typically use heroin two to six times a day.

Another way to estimate quantity is to ask the patient how much he or she has been spending on average each day or week to purchase heroin. Drug prices vary widely based upon geography (even between neighborhoods) and demand [24]. A typical "quarter bag" ($25 worth) has enough adulterated heroin powder to snort several lines or inject several times, depending upon the tolerance of the buyer. Amounts used can range from $20 to $200 per day. Although typical street-level drug transactions are for standard dollar amounts (ie, $10, $20, or $50), the actual amount of pure heroin sold for a given price changes with time and location of sale.

Addicts do not always engage in a cash transaction to obtain drugs. Acquiring drugs often involves trading stolen goods for drugs, engaging in prostitution, trading favors (such as the use of a car or house) with the dealer, or getting heroin from friends at no charge. Many drug users share illicit drugs without taking money, with an expectation of reciprocity: that they will get drugs from others when they need them in the future [23].

It is important to determine if the patient is dependent on or abusing other drugs and/or alcohol in addition to opioids. Obtaining an accurate history can be complicated, as patients may accelerate use of one substance (eg, alcohol) during times when heroin is less available. The clinician must accurately identify patients who need concomitant treatment of alcohol or sedative/hypnotic dependence because withdrawal from these drugs can be life threatening.

The clinician should determine whether the patient has been using larger and larger amounts of heroin to get the same effect. This demonstrates tolerance to opioids and indicates that the patient is likely to experience withdrawal symptoms if he or she stops using abruptly. Many addicts start out using heroin to get high, then reach a point where they must use simply to avoid withdrawal symptoms.

Another important element of the history involves asking about previous substance abuse treatment. Ask when the patient has been in treatment and what type (detoxification, opioid maintenance, inpatient, residential, outpatient counseling, or self-help groups such as Narcotics Anonymous). Asking the length of the longest period of abstinence helps predict the patient's ability to maintain abstinence in the future. Abstaining from heroin for at least one year suggests a favorable prognosis for remaining abstinent again for a significant period of time.

Asking about problems that have resulted from drug use helps the patient to begin thinking about reasons to stop using drugs. Patients should be asked about past and present physical and psychiatric conditions as well as legal and social problems, especially if the patient has lost jobs, relationships, or freedom as a consequence of heroin use.

PHYSICAL EXAMINATION — A routine physical examination can elucidate common complications of heroin use or assist in diagnosing opioid dependence. Chronic intravenous use can be confirmed by the presence of "track" marks, which are callouses that follow the course of a subcutaneous vein. These are caused by repeated injections into adjacent sites over an accessible vein. Tracks are often found in easily accessible body areas, such as the backs of the hands, antecubital fossae, on the legs, or in the neck. Signs of recent injection may be found in unusual places in patients attempting to hide their sites of injection. A thorough examination for tracks or recent injection sites should include looking between the fingers and toes, under the fingernails and toenails, in the axillae, breast veins, and the dorsal vein of the penis.

The nasal septum should be examined for perforation from repeated intranasal insufflation (especially when cocaine is mixed with heroin and snorted). A heart murmur may indicate subacute bacterial endocarditis. Posterior cervical lymphadenopathy may suggest early viral infection, especially with HIV. Hepatic enlargement may indicate acute hepatitis; a small, hard liver is consistent with chronic viral hepatitis due to hepatitis B or C virus, which is common among injection drug users who share needles.

Signs of opioid intoxication may include pinpoint pupils, drowsiness, slurred speech, and impaired cognition. Signs of acute opioid withdrawal syndrome include watering eyes, runny nose, yawning, muscle twitching, hyperactive bowel sounds, and piloerection.

LABORATORY EVALUATION — Patients who use heroin are at risk for infections related to shared needle use, including HIV and hepatitis. When a patient has been identified as abusing heroin, counseling regarding HIV testing should be provided, and testing encouraged. Patients should also be tested for hepatitis A, B, and C. Hepatitis A and hepatitis B vaccination should be given to patients whose hepatitis serology is negative. A complete blood count and liver function studies are appropriate and may suggest need for further investigations. (See "Overview of the recognition and management of the drug abuser", section on Laboratory findings).

SUMMARY AND RECOMMENDATIONS

• Heroin, taken intranasally, intravenously, or by smoking, is the opioid most likely to result in overdose because of variability in potency of street preparations. Prescription opioid analgesics are the most commonly abused opioids in the US. (See "Introduction" above and see "Overdose" above and see "Other opioids" above).

• Urine drug screens can detect opioid metabolites within four days of last use, and possibly longer in chronic users. False negative tests may occur because not all opioids are detected in drug screens, and false positive tests can be seen in patients taking rifampin, quinolones, or eating poppy seeds. (See "Detection in drug screens" above).

• Consequences of heroin addiction are increased mortality, increased crime, and infections related to shared needles, endocarditis, and localized infections from non-sterile technique. (See "Consequences of abuse" above).

• Ask patients about amount, frequency, and duration of heroin or other opioid abuse, and look for signs of use on physical examination. (See "History" above and see "Physical examination" above).

• Identified heroin users should be screened for HIV and hepatitis A, B, and C. Vaccination for hepatitis A and hepatitis B should be given to those with negative serologies. (See "Laboratory evaluation" above).

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