eMedicine Specialties > Psychiatry > Addiction

Injecting Drug Use

Author: Gloria J Baciewicz, MD, Director of Addiction Psychiatry Program, Clinical Associate Professor, Department of Psychiatry, Strong Memorial Hospital, University of Rochester
Contributor Information and Disclosures

Updated: Aug 5, 2008

Introduction

Background

The hypodermic syringe was invented in the mid-1800s. By the late 1800s and early 1900s in the United States, the public could purchase hypodermic needles and syringes legally, and opiates and cocaine were widely available. The Harrison Act in 1914 allowed narcotics to be dispensed only by a prescription from physicians or dentists. Several states also developed legislation preventing the sale of hypodermic syringes and needles without a prescription.

Most individuals who use injection drugs inject their drugs intravenously, but subcutaneous injection (ie, "skin-popping") is also common, and intramuscular injection may occur intentionally or when the individual misses the vein or the subcutaneous space. Injecting drug use is associated with many local and systemic complications for the individual and is also associated with the transmission of infectious diseases via needle sharing and sexual activity. The most commonly injected drug is heroin, but amphetamines, buprenorphine, benzodiazepines, barbiturates, cocaine, and methamphetamine also are injected. Any water-soluble drug may be injected. Treatment of individuals who use injection drugs may be complicated by social and political barriers to treatment and by a lack of resources for public health approaches to treatment.

Both illegal drug production and injecting drug use have been globalized in recent years. Injecting drug use has diffused to countries that formerly had little problem with it. Both injecting drug use and HIV infection can spread rapidly within a community. Introduction of and rapid increase in injecting drug use is believed to be responsible for dramatic increases in HIV infection in some areas. In China, in Central Asia, and in several countries of Eastern Europe, injecting drug use is the primary risk factor for HIV infection.

See related Medscape CME activity, The Dark Side of Drug Addicition.

Pathophysiology

When injecting a drug intravenously, the individual introduces a bolus of the drug into the vein, producing a rapid and powerful drug high. The onset of drug effects is about 15-30 seconds for the intravenous route and 3-5 minutes for the intramuscular or subcutaneous route. Drug effects from inhaling (ie, smoking) a drug begin in 7-10 seconds, and drug effects from intranasal use (ie, transmucosal absorption) begin in 3-5 minutes.

Injecting drug use causes medical problems by introducing pathogens and other contaminants into the body via shared needles and a lack of sterile preparation and injection techniques. Medical problems also arise from damage caused by the drugs themselves (eg, morbidity and mortality associated with drug overdose). The injected drugs also may not be pure; they may be cut with irritants, such as talc, lactate, or quinine.

Death from the direct toxic effects of a heroin overdose itself is usually associated with respiratory depression, coma, and pulmonary edema. Death from the direct effects of cocaine is often associated with cardiac dysrhythmias and conduction disturbances, leading to myocardial infarction and stroke.

Frequency

United States

In 2003, the United Nations Office on Drugs and Crime estimated about 1.4 million people used injection drugs in North America.

International

The United Nations Office on Drugs and Crime reported that an approximate 13 million people used injection drugs worldwide in 2003, with 130 countries providing information and 78% residing in developing countries. About 8.8 million are in Eastern Europe and Central, South, and Southeast Asia. About 1 million are in Latin America.

Mortality/Morbidity

Morbidity and mortality may result from infection secondary to injecting drug use, sequelae of injection with adulterants added to the drug mixture, sequelae of the drug use itself, drug overdose, or violence associated with drug use.

• Worldwide, 39.5 million people are living with HIV/AIDS. Of that number, 2-3 million use injection drugs. Besides direct transmission of HIV, injecting drug use also contributes to the spread of HIV infection by perinatal transmission and by sexual contact with individuals who do not inject drugs.¹ Injecting drug use is also associated with increased levels of high-risk sexual behavior.
• Worldwide, 40-60% of individuals who use injection drugs are estimated to be positive for hepatitis B, and 60-70% are positive for hepatitis C virus (HCV). HCV rates are high even in countries with low HIV seroprevalence. Injecting drug use is responsible for approximately 60% of HCV infections in the United States. New HCV infections in the United States have declined since 1989² , but the incidence and prevalence of HCV remains high. The spread of HCV is rapid among those who are new to injecting drugs; in the United States, following initiation of injecting drug use, 50-80% become infected with HCV within 6-12 months. For related information, see Medscape's Hepatitis B and Hepatitis C Resource Centers.
• The mortality from all causes in individuals who use injection drugs is estimated to be 3-4% per year.

Race

The National Survey on Drug Use and Health (NSDUH) found no differences in injection drug use reports by race or ethnicity in the United States in 2002 and 2003.

Sex

• Combined 2002-2005 data from NSDUH indicate that US males were twice as likely as females to report injection drug use in the past year.
• The Centers for Disease Control and Prevention in the United States reports that 24% of males and 25% of females living with HIV/AIDS in 2003 used injection drugs.³ Another significant source of HIV infection for women is sex with partners who use injection drugs. An estimated 61% of AIDS cases in women can be attributed to injecting drug use or to sex with partners who use injection drugs. Females may use more shared injecting drug use equipment than males.⁴
• Worldwide, 70-90% of those who use injection drugs are believed to be male.

Age

• The purity of heroin has been increasing, and its cost has been decreasing. Because of these factors and because of their initial desire to avoid injecting drug use, many  adolescent and young adult in the United States and Europe using heroin for the first time try snorting, sniffing, or smoking heroin. New noninjecting heroin users risk making a transition to injecting drug use when their need for heroin use intensifies.
• Among adolescents who inject drugs, early school truancy and expulsion may be a predictor of injecting drug use. A younger age of initiation into injecting drug use is associated with more frequent reports of risky drug use and sexual practices, as well as higher rates of HIV infection.⁵

Clinical

History

• Obtain a complete history of the individual's past alcohol and drug use, including the following:
  • Age of onset for each drug used
  • Frequency of use
  • Quantities used
  • Progression of use with time
  • Medical and psychiatric symptoms associated with use
  • Routes of administration for each drug
  • Means of obtaining drugs or money for drugs
  • Longest periods of abstinence from drug use
  • History of prior chemical dependency treatments
• Ask those who report injecting drug use which injecting sites they use, whether they use new or used needles, and whether they share other items used in the preparation of drugs for injection (eg, cookers, cotton). Ask those who share needles and syringes whether they attempt to clean the needles (eg, by using a bleach kit distributed by outreach workers).
• Other risks associated with injecting drug use include contaminated drug solutions, buying ready-filled syringes, and sharing rinse water. "Backloading" is a practice in which a dealer transfers the drug solution from a larger syringe to a syringe provided by the user. "Flashblood" is a practice initially reported among sex workers in Dar es Salaam, in which an individual draws blood back into the syringe after having injected heroin, and then passes the syringe to another individual to inject the blood in the belief that this will prevent withdrawal symptoms.
• Individuals may inject substances that are not supposed to be injected, such as pulverized (and unsterile) pills mixed with liquid. The liquid used to prepare drugs for injection is usually water, although use of lemonade and vinegar for this purpose has also been reported.
• Ask about a history of prior systemic or local infections secondary to injecting drug use.

Physical

• Begin with a standard physical assessment, paying special attention to signs of current injecting drug use, such as needle tracks. Other physical signs related to alcohol and drug use may also be present.
  • Common injection sites, such as the antecubital areas, should be inspected for evidence of recent injection. Some individuals may also use more unusual sites for injection, such as veins in the feet, hands, groin, and even the neck. As individuals who use injection drugs age and commonly used veins sclerose, these individuals may select progressively more dangerous sites. Hospitalized patients and patients who receive intravenous medication may inject drugs into their indwelling intravenous lines.
  • Check vital signs because changes are commonly associated with alcohol and drug intoxication and withdrawal, as well as with systemic infections secondary to injecting drug use. Stimulants, such as cocaine, may cause hyperthermia, an easily treatable yet easily overlooked condition. Persons who are intoxicated may also present with hypothermia, especially if they have been confused and wandering outside in cold weather.
• Perform a mental status examination. Pay special attention to level of alertness because many drug and alcohol intoxication and withdrawal states can produce changes in alertness and orientation. Assess affect and mood and note whether suicidal ideation or intent is present. Drugs of abuse may cause or exacerbate depression and suicidal ideation. Determine the presence or absence of homicidal or violent intent and ask whether the patient has guns at home. Assess thought content and the presence or absence of hallucinations, delusions, or paranoid ideation and ask the patient whether these phenomena seem to be exacerbated or caused by drug use. Many patients with drug-induced delusions or hallucinations are in fact aware of the relationship between their drug use and the delusions or hallucinations.

Causes

• Individuals begin using addictive drugs for various reasons; some are seeking a high, some wish to relieve dysphoria, and some seek escape from intolerable feelings or thoughts.
  • Craving for addictive drugs is associated with increased activation of brain reward areas, including the nucleus accumbens and other brain areas. Drug use directly or indirectly elevates dopamine levels in the mesolimbic pathway of the brain, producing a pleasurable and positively reinforcing high.
  • Those who are at risk for developing dependence on addictive drugs may have a genetic predilection for this problem. 
  • Neuronal changes in specific brain regions (ie, neuroadaptation) occur in response to repeated drug use. Thus differences exist in the brains of addicted and nonaddicted individuals, and these differences can be demonstrated by brain imaging techniques.
• Those who use drugs experience a compulsion to use the addictive drug regardless of negative consequences.
• Those who use drugs may make the transition from noninjecting drug use to injecting drug use as their dependence on the drug becomes more severe. Injecting drug use is a popular route of drug administration because the injected substance has almost 100% bioavailability, and the onset of the drug high is fairly rapid, generally 15-30 seconds.
• Those who use drugs use nonsterile injecting equipment largely because of the scarcity of sterile needles and syringes. Many people will use sterile needles and syringes if provided access to them. Making sterile injecting equipment available, either for purchase or via a needle exchange program, decreases rates of HIV and hepatitis B infections.

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