Substance Use Disorders (SUDs) are highly prevalent disorders that are characterized by an inability to control the use of a legal or illegal drug, medication or other psychoactive compound. SUDs typically occur following prolonged, repeated use of a substance at high doses and/or high frequencies and can lead to significant health and social consequences. According to the National Survey on Drug Use and Health, 19.7 million adults in the United States suffered from an SUD in 2017. SUDs and related disorders are a significant source of morbidity and mortality and pose a substantial cost to society. It is estimated that drug abuse and addiction costs American society more than $740 billion annually in healthcare expenses, lost workplace productivity, and crime-related costs.
Opioid Use Disorder (OUD) is a form of SUD characterized by uncontrolled and persistent self-administration of opioids, resulting in significant impairment, distress, and mortality. In 2017, an estimated 2.1 million people in the United States had an OUD, and 47,600 people died from an opioid drug overdose. OUD’s societal effects are extremely far-reaching as the condition burdens multiple stakeholders. A retrospective secondary analysis using 2018 data from the National Survey on Drug Use and Health and the CDC WONDER Database attributed to OUD a $787 billion societal cost in the United States alone. The most common treatments for OUD are directed at achieving abstinence and include psychological and social interventions.
Pain and OUD are Linked
For many patients, pain relief and addiction are fundamentally linked, since the use of opioids to manage acute pain can lead to drug dependence. While opioids are indeed effective for most forms of acute pain, they are associated with a variety of adverse effects, including risk of addiction, constipation and respiratory depression, the latter being the main cause of death among opioid users. Of individuals prescribed at least one day of opioids, 6% are still taking them one year later. Moreover, it is estimated that 8% to 12% of individuals prescribed opioids for chronic pain ultimately develop OUD.
There are limited pharmacological agents available to treat OUD, with the current options divided into two classes: (i) synthetic opioid receptor agonists, such as buprenorphine and methadone, and (ii) opioid antagonists, such as naltrexone and naloxone. These therapies suffer from a number of limitations, including high relapse rates, inconvenient treatment regimens and access, partly due to treatments being controlled substances, which limit treatment availability and adherence, and an inability to maintain abstinence after medically assisted withdrawal.
Buprenorphine, methadone and naltrexone are used as maintenance therapy with the primary goal of preventing relapse while naloxone is used as rescue therapy for opioid overdose. Access to treatments such as buprenorphine and methadone is limited by their treatment regimens and inherent risks of abuse, placing significant requirements and regulations on practitioners. In addition to these limitations, current treatment options are not highly effective; approximately 75% of patients undergoing OUD therapy experience relapse within one year of treatment. For abuse of other substances, such as cocaine or methamphetamine, no pharmacological agents have been approved.
Despite the limitations of current treatment options, the worldwide market for OUD therapies totaled $1.9 billion in 2018, the majority of which came from the United States. Furthermore, due to the significant increase in opioid use and the heightened response to the opioid crisis, the worldwide market for opioid abuse therapies is projected to grow by over 10% per year, signaling significant need for new treatment options.