Characterization of Prescription Opioid Abuse in the United States: Focus on Route of Administration

ABSTRACT

Prescription opioids are prescribed increasingly for the management of chronic pain, and this has been accompanied by a dramatic rise in opioid-related abuse, addiction, and overdose deaths. Reports of abuse involving nonoral administration (e.g., snorting, injecting) of prescription opioids are increasing, although the epidemiology of oral versus nonoral abuse is not well understood. Available data indicate that oral abuse is far more common, with 72% to 97% of opioid abusers perferring oral administration. Factors associated with nonoral administration include longer duration of opioid abuse, male gender, and rural setting. Extended-release opioids, because of their relatively high drug load, may be attractive to experienced abusers seeking to manipulate the formulation to facilitate a rapid onset of effect. Putative abuse-deterrent formulations have been developed to decrease the likelihood or consequences of nonoral abuse. In addition, Risk Evaluation and Mitigation Strategies (REMS) are now required for prescribed extended-release/long-acting opioids by the US Food and Drug Administration, although their effectiveness in reducing the risk of abuse, addiction, and overdose has not been evaluated. Physicians should remain vigilant when prescribing opioids and should exercise appropriate patient selection, perform risk analysis and stratification, and maintain continuous patient monitoring to ensure the benefits outweigh these important risks.

KEYWORDS :

• abuse
• abuse-deterrent
• abuse potential
• abuse-resistant
• tamper-resistant
• opioids

Notes

a There are several terms in the literature used to refer to scheduled narcotic drugs (i.e., controlled substances regulated under the Controlled Substances Act), including “opioids,” “prescription opioids,” “opiates,” “pain relievers,” “painkillers,” etc. In this paper, the authors use the term “prescription opioids” to refer to this class of medication.

b Abuse has been defined as “any use of an illegal drug, or the intentional self-administration of a medication for a nonmedical purpose, such as for altering one's state of consciousness (e.g., getting high).”⁴ However, other expressions, including “nonmedical use” and “misuse,” have been used to describe the same behavior.

c The wide range of estimates of abuse prevalence is likely accounted for, at least in part, by the different definitions of abuse used in each study.

d Nonmedical use is defined in the National Survey on Drug Use and Health as “use of at least one of four classes of prescription-type psychotherapeutics (pain relievers, sedatives, stimulants, and tranquilizers) without a prescription belonging to the respondent or use that occurred simply for the experience or feeling the drug caused.”¹² Although very similar to most definitions of abuse, nonmedical use leaves open the possibility that the respondent, while not having a legitimate prescription, administered the drug to treat a legitimate medical condition.

e Similar to definition inconsistencies of other terms, there is no uniform definition for “diversion” or “diverted.” In this context, diversion is defined as “the intentional removal of a medication from legitimate distribution and dispensing channels.”⁴

f The federal survey referenced used this terminology to describe scheduled and nonscheduled prescription opioids.

g This expression refers to persons who feign pain symptoms and visit multiple doctors for the purpose of obtaining prescriptions for medications such as opioids with the intention of redistribution or abuse.

h Defined as drug overdoses resulting from drug misuse, drug abuse, and taking too much of a drug for medical reasons.

i Even in this paper, the authors found it necessary to define ambiguous terms used in the cited research (e.g., “pain relievers”).

j In April 2010, OxyContin was reformulated by its sponsor, Purdue Pharma Inc., with an improved delivery system and a proprietary formulation that is expected to deter nonoral abuse of the drug.³⁰

k Poisoning deaths include those resulting from accidental or intentional overdoses of a drug, being given the wrong drug, taking the wrong drug in error, or taking a drug inadvertently. Estimates are based on the National Vital Statistics System multiple cause of death mortality files. Poisoning deaths were defined as those with an underlying cause of death classified according to the International Classification of Diseases, Tenth Revision (ICD-10), external cause of injury codes X40–X49, X60–X69, X85–X90, Y10–Y19, Y35.2, or *U01(.6–.7). Estimates are for poisoning deaths of any intent (unintentional, suicide, homicide or legal intervention, or undetermined) for US residents.

l This formulation is not approved by the Food and Drug Administration (FDA). The drug sponsor received a complete response letter from the FDA on the resubmission of the new drug application (NDA) on June 24, 2011. According to the company's Web site, Pfizer is working to evaluate the issues described in the letter.⁵⁶