This is the first study, to our knowledge, to describe the context for initiation into prescription opioid misuse, subsequent pathways into injecting opioids, and implications for current patterns of opioid and heroin misuse among a sample of young IDUs.
Initiation into opioid misuse was characterised by access or exposure to three primary sources of opioids – family members, personal prescription, or friends – while friends were the most commonly reported source. However, as young people progressed to sniffing and/or injecting opioids, they often had access to two or more sources of opioids, e.g., family and friends. Understanding sources of opioids as multiple and often overlapping – rather than mutually exclusive categories - is an important distinction made in previous research on young non-IDUs (McCabe & Boyd, 2005
; Schepis & Krishnan-Sarin, 2009
). Additionally, the young people clearly regarded prescription opioids – regardless of source – as readily accessible, valued commodities that could be traded or sold (McCabe et al. 2006
). In numerous cases, the desire to experiment with a prescription opioid combined with financial incentives or pressures from friends to sell available quantities, resulted in escalated patterns of opioid misuse. Furthermore, the progression from initiating misuse with Vicodin – amongst the most widely prescribed opioid in the U.S. (Schneider et al. 2009
) – to later sniffing and/or injecting OxyContin – a less commonly prescribed but more potent opioid (Schneider et al. 2009
) – indicates increasingly sophisticated users with access to varied sources of opioids (Davis & Johnson, 2008
The broader context of initiation into prescription opioid misuse was characterised by the substance misuse of family members and young people with psychological conditions. Most witnessed family members misuse one or more substances during childhood and adolescence, which ranged from alcoholism to misusing opioids to injecting heroin (Finestone and Fischer, 2008). In households where problematic drug use by parents and siblings became “normalised” (Parker, 1998
; MacDonald & Marsh, 2002
), young peoples’ misuse of opioids or other drugs was seldom discovered by adults or viewed as aberrant. In these environments, young people were confronting a range of mental health issues or stressful life events, as suggested by the high frequency of prescribed psychological medications. Initiation into prescription opioid misuse often occurred during the same time periods that young people witnessed substance use by family members or received psychological diagnoses and medications.
An emerging dynamic among opioid and heroin misuse and injection drug use is suggested by two findings. First, four of five IDUs misused an opioid before injecting heroin, which is in contrast to more conventional patterns of using opioids as a substitute drug after initiating heroin use (Chein et al., 1964
; Faupel, 1991
; Daniulaityte et al., 2006
). Second, nearly one out of four young IDUs initiated injection drug use with a prescription opioid – substances that are infrequently reported at initiation into injection drug use among young IDUs (Lankenau et al., 2007b
). All but two of these IDUs later transitioned into injecting heroin. These initiation patterns corroborate findings from recent research on broader samples, i.e., not exclusively young adults or IDUs, suggesting that opioid misuse (Siegal et al. 2003
; Daniulaityte et al., 2006
; Inciardi et al. 2009
) or polyopioid misuse (Grau et al., 2007
) may serve as a gateway to heroin. However, this is the first study to our knowledge, among a sample of young IDUs - amidst this recent epidemic of prescription drug misuse (c.f., Courtwright, 1982
; Hernandez & Nelson, 2010
) – to report a trajectory from opioid misuse to injecting heroin or injecting both opioids and heroin. Identifying emerging pathways into injection drug use that begins with misuse of opioids is important given the prevalence of prescription opioid misuse among adolescents (Johnston et al., 2010
) and young adults (SAMSHA, 2010a
) and the risks associated with transitioning into injection drug use (Fuller et al., 2002
; Sherman et al., 2006; Roy et al., 2008
Trajectories into opioid injection were related to variability in access or exposure to sources of opioids in some cases. IDUs who injected an opioid first had the greatest access to prescription opioids – either through family or their own prescription – and were most involved in selling prescription opioids. These IDUs also initiated opioid injection at the youngest age and currently reported the most frequent misuse of prescription opioids. In contrast, IDUs who injected heroin first were the most heroin-involved group; a majority reported current daily heroin use. They frequently initiated prescription opioid injection as a substitute for heroin when experiencing withdrawals from heroin. IDUs who never injected an opioid were the least opiate-involved: they initiated opioid misuse at the latest age, had the least access to opioids as adolescents, were the least involved in selling opioids, and currently misused opioids less frequently. This last group - an important counterpoint to the other two – suggests that less exposure to prescription opioids among other factors, such as stigma associated with injecting opioids or “junkie behavior” (Small et al., 2009
) and less use of heroin, may mitigate transitions into injecting prescription opioids.
Changes in the broader illicit markets for heroin and prescription opioids in Los Angeles and New York at the time of the study may be relevant to overall reported patterns of drug use. Between 2005 and 2008, the cost of heroin – Colombian “powder” commonly found in New York and Mexican “tar” typically found in Los Angeles - increased while purity declined in both cities (NIDA, 2010
), though, powder heroin found in New York was cheaper and purer than tar heroin found in Los Angeles. Meanwhile, retail sales of hydrocodone and oxycodone increased between 2007 and 2008 in Los Angeles, which may suggest an increase in overall supply for illicit use. These differences in the heroin and prescription opioid market costs could partially explain why New York IDUs were more likely to report heroin as the most frequently used drug, while Los Angeles IDUs were more likely to report a prescription opioid. In both cities, the practice of substituting a prescription opioid for heroin – even among IDUs who became regular heroin injectors – could be linked to issues of increasing costs and declining heroin purity. Additionally, the greater challenges associated with converting tar heroin to a soluble form, which requires heating (Ciccarone 1999) versus crushing a pill, could help explain the finding that a larger proportion of IDUs who injected a prescription opioid before heroin were from Los Angeles.
Prevention efforts should focus on the three to four years during adolescence that typically separated first opioid misuse from initiation to opioid injection – especially since heroin initiation commonly occurred between these two events. Towards this end, study data suggests that parents and guardians need to exert greater control over all prescription medications within the household, opioids in particular, given the increasing rate that these potent medications are being prescribed (NIDA, 2010
). A complication for prevention efforts - as suggested by this study - are those households where illicit and/or licit drug use is normalised. In such environments, access to prescription opioids among adolescents is likely to be linked to broader social or psychological problems, such as illnesses, addiction, and/or numerous types of inequalities, which are more difficult to remedy through prevention efforts or policy changes. Nonetheless, future research should examine prescription opioid misuse among a range of adolescents and young adults - both IDUs and non-IDUs - to better understand the contextual and environmental factors that inhibit or accelerate transitions to both heroin and injection drug use.
The study has several limitations. First, data may be subject to recall bias since the events reported often occurred years prior to being interviewed, such as ages of initiation or details of particular injection events. Second, the enrollment criteria were designed to capture young IDUs who were currently misusing prescription drugs. However, even though all participants misused prescription opioids, current misuse of opioids was not an enrollment criterion. Nonetheless, results may be biased towards IDUs who more frequently misused a range of prescription drugs, including opioids. Third, the sampling methods captured a sample that was largely white, male, and heterosexual. Hence, young people of colour, women, or sexual minorities who inject drugs may evidence different patterns of prescription drug misuse.