Nora D. Volkow M.D.
National Institute on Drug Abuse
National Institutes of Health
U.S. Department of Health and Human Services
Treating Addiction as a Disease: The Promise of Medication-Assisted Recovery
Committee on Oversight and Government Reform
Subcommittee on Domestic Policy
United States House of Representatives
Wednesday June 23, 2010
Mr. Chairman and Members of the Subcommittee, as the Director of the National Institute on Drug Abuse (NIDA), part of the National Institutes of Health, an agency of the Department of Health and Human Services, it is a privilege to be here with my colleagues to present NIDA’s perspective on the opportunities and barriers to the development of addiction medications and their integration into substance abuse treatment.
We have a public health mandate to stop the devastating scourge of drug abuse and addiction afflicting this country, and new medications to treat addiction could go a long way to achieving this end. It is a gaping need. A recent report from HHS’s Centers for Disease Control and Prevention finds that drug-induced deaths, mainly from opioid pain reliever overdose, more than tripled from 4,000 in 1999 to 13,800 in 2006. And cigarettes continue to kill roughly 440,000 people each year in this country—yet the quest to discover treatments for nicotine addiction lags behind the efforts to develop medications for the diseases it causes. From 1987 to 2008, 174 medications trials were done for smoking cessation (46 supported by industry), compared with 1,490 clinical trials for lung cancer treatment (544 supported by industry). The possibilities present in the knowledge we have accumulated, if translated into new medications today, could transform the way we treat addiction and even how we prevent drug abuse from occurring in the first place.
Science has shown, beyond a reasonable doubt, that addiction is a disease of the brain, and that our genes contribute close to half of the risk for becoming addicted. Addiction results from profound disruptions in the function of specific neurotransmitters and brain circuits. It involves an expanding cycle of dysfunction, first in the areas of the brain that process reward, followed by alterations in:
- complex cognitive functions, such as learning (memory, conditioning, habits);
- executive function (impulse inhibition, decision making, delayed gratification);
- cognitive awareness (interoception); and
- emotional functions (mood, stress reactivity).
These circuits work together and change with experience. Eventually, with repeated drug exposure, they become recalibrated, tilting the balance away from volitional control over one’s behavior toward behaviors driven by drug cues and drug cravings. The result is compulsive drug use, despite severe health and social consequences. In fact, that is the hallmark of addiction.
New Knowledge Presents New Medications Possibilities for Drug Abuse
This knowledge and other discoveries have given us numerous molecules and circuits that could serve as the basis for new approaches to medications development. Medications that target systems common to multiple addictions (e.g., stress-induced relapse) could widen the market for addiction medications and compel greater interest from pharmaceutical companies. In fact, the current pipeline of smart pharmacotherapeutic strategies embodies the translational potential of what we now know about addiction. For example:
Addiction vaccines. Vaccination is a centuries-old strategy in which the body is coaxed into producing antibodies that neutralize disease-causing agents (e.g., viruses, parasites, toxins). The concept behind this classic form of immunotherapy has only recently been explored and shown to be viable for treating addiction. In this case, antibodies are generated to specific abused drugs to bind the drug while it is still in the bloodstream, thereby reducing its entry into the central nervous system and blocking its pharmacological/behavioral effects. This approach, applied so far against nicotine and cocaine, has shown considerable promise.. NicVAX, a nicotine vaccine developed by Nabi Biopharmaceuticals, is now in Phase III clinical trials for drug approval owing in part to NIDA support using American Reinvestment and Recovery Act funds. Although not yet approved by the U.S. Food and Drug Administration (FDA) for safety and efficacy, preliminary results show that smokers who achieved high antibody levels had higher rates of quitting and longer stretches of abstinence than those given placebo (18% vs. 6% complete abstinence after 52 weeks). The vaccine was also well tolerated, with few side effects; and it reduced craving and withdrawal symptoms, which often prompt relapse.
Long Acting (Depot) Medications (e.g., Vivitrol—injectable naltrexonecurrentlyprescribed for alcoholism). Recent clinical trials of Vivitrol for opioid dependence have produced spectacular results showing this compound could be of great help in situations where opiate replacement therapy is rejected or when the patients are hard to reach, because long-acting, or depot, medications have effects that last for weeks instead of hours and therefore promote adherence. Here, too, these results are under review by the FDA, but the drug is not yet approved for safety and efficacy. However, if approved, treatment with this drug could also be more cost-effective due to decreased clinical support with fewer clinical visits. A study of Vivitrol among people addicted to heroin in Russia found a median 90% rate of opioid-free urines in the group receiving the medication versus 35% among controls; a 50% reduction in opioid craving versus no change for placebo; and a 75% longer retention in treatment for Vivitrol patients versus the control group. Such promising results could greatly impact the public health in Eastern Europe and Central Asia, where the intertwined epidemics of injection drug use and HIV are fueling devastating disease and societal disintegration, as well as here in the United States, particularly within the criminal justice system, where NIDA is currently studying Vivitrol’s effectiveness.
Medication combinations have emerged as a promising strategy for treating addictions. This includes marijuana addiction, which accounts for approximately 4 million of the estimated 7 million Americans classified with dependence on or abuse of illicit drugs. Withdrawal symptoms—irritability, sleeplessness, increased appetite, drug craving—often prompt relapse in those trying to quit, but the combination of lofexidine (a medication to treat hypertension, approved in the U.K.) and dronabinol (an oral form of tetrahydrocannabinol (THC), the psychoactive ingredient in marijuana) has produced robust improvements in disordered sleep patterns, plus decreased marijuana withdrawal, craving, and relapse in daily marijuana smokers. Preliminary data also suggest the safety and possible efficacy of combined buprenorphine and naltrexone, for the treatment of cocaine addiction. Such findings are especially important since no medications currently exist for addiction to marijuana or addiction to cocaine.
Personalized approaches. Rapid advances in the science of genetics and related technologies are ushering in the age of personalized medicine, giving physicians and patients a greater understanding of health and disease at the molecular level. The field of pharmacogenetics, which deals with the influence of genetic variation on drug response in patients by correlating genetic polymorphisms and/or gene expression with drug efficacy, is opening up new worlds in addiction medicine possibilities. For example, a genetic variation has been identified that may help predict alcoholic patients’ response to naltrexone (a µ-opioid receptor blocker). Specifically, a functional polymorphism of the µ-opioid receptor gene, found in about 15 to 25 percent of the general population, has been linked to naltrexone’s efficacy in treating alcoholism; similar findings are also emerging in the treatment of nicotine addiction. As here, prescribing physicians may be able to improve and individualize patient treatment by taking genetic variation into account.
New obstacles are appearing alongside existing ones, on both the medications development and service delivery fronts, that could restrain truly remarkable opportunities.
For instance, the cost of developing a new medication and bringing it to market can be, according to recent estimates, up to $2 billion. NIDA needs to leverage research and technical assistance in partnership with private entities to help bring a medication to market. Securing pharmaceutical industry involvement has been difficult, due largely to perceived financial disincentives. Many pharmaceutical companies have traditionally shied away from medications development for illicit drug disorders because of a relatively small patient population who also tend to be in lower income brackets, lack health insurance, or rely on the State for their care. Added to this is the stigma that still attaches to illicit drug addiction, along with concerns about this population’s compromised health overall, which may present drug safety and other liability issues that further discourage pharmaceutical involvement. However, the implementation of the Mental Health Parity and Addiction Equity Act of 2008 and the increased accessibility to insurance coverage for those with lower incomes provided by the Affordable Care Act promise to expand access to substance abuse treatment and thereby open up the market for addiction medications. Moreover, capitalizing on new approaches that target brain circuits and molecules common to multiple addictions, including alcohol and tobacco, can also help increase market share, reduce stigma, and better engage pharmaceutical companies.
The reluctance of private companies to fully engage in the research and development of addiction medications has encumbered our ability to harness the full clinical potential of scientific discovery. But now, the problem is poised to worsen, as the pharmaceutical industry plans to reduce their investment in psychotherapeutics research and medications development. Not only does this situation impede the development of medications for mental illnesses generally, but it contracts the pool of available medications for secondary uses, including to treat drug addiction. This is a serious trend in a country where approximately one in four adults suffers from a diagnosable mental disorder in a given year and where, among the 9.8 million adults with serious mental illness, 1 in 4 also abuse or are dependent on illicit drugs or alcohol. This high rate of comorbidity, together with fewer medications to treat both illnesses, could adversely affect the public health.
Getting Treatments to People Who Need Them
While developing medications to treat addictions is important, access to these medications as well as other substance abuse treatment services will be critical to improving outcomes for those struggling with substance abuse and addiction. It is a sad fact that more than 90% of the 23 million Americans in need of treatment for substance use disorders do not receive it. In addition, many treatments, including nicotine replacement therapies, are not effective without behavioral therapies or social networks to help patients achieve abstinence. NIDA is actively engaged in efforts to change this situation, working through multiple venues, but especially the medical community and the criminal justice system.
The medical community
Substance abuse is a chronic, relapsing medical disease. To treat this disease effectively, we must—as a public health priority—promote the integration of addiction treatment into the rest of the health care system. Failing to do so denies addiction’s probable complicity in and possible deleterious effects on other medical conditions or diagnoses. Mainstreaming substance abuse treatment requires that we engage primary care physicians, who are in a unique position to identify drug use early and prevent its escalation to addiction and/or to treat or refer patients with potential substance use problems. Yet physicians tend not to prescribe proven addiction medications or to proactively identify potential problematic substance use in their patients. NIDA is working to change this circumstance through physician outreach and other initiatives.
Having addiction medications available could further engage the medical community in providing substance abuse treatment, helping patients recover from their substance use while also benefiting myriad other health conditions where drug use may affect the course and progression. We must therefore remain vigilant in our efforts to educate the healthcare community to properly screen for and treat substance use disorders.
The criminal justice system
Criminal justice settings offer prime venues for implementing evidence-based treatments among a high-risk population. More than half of incarcerated individuals have a substance use history, but rather than capitalizing on the opportunity to effectively treat this high-risk population, we continue to release prisoners without any provision or mechanism for follow-up treatment, in spite of known consequences: greater recidivism, relapse, and post-release mortality.
For example, more than 200,000 people addicted to heroin pass through American correctional facilities each year. Opioid maintenance therapy (e.g., methadone or buprenorphine) exemplifies a treatment that has proven effective in treating opioid dependence and in reducing drug-related disease and criminal recidivism. In a randomized clinical trial of methadone maintenance among 200 prisoners with pre-incarceration heroin dependence, those who received counseling plus methadone maintenance in prison with continued treatment in the community upon release were significantly less likely to be opioid- or cocaine-positive according to urine drug testing than those who received counseling only with passive referral or those who received counseling in prison with transfer to methadone upon release. Other research points to buprenorphine treatment as a promising intervention for prisoners with heroin addiction histories and stresses that challenges related to dosing, administration, and regulation can be overcome via collaboration among treatment, research, and correctional personnel, particularly important at the Federal Government level (e.g., Federal Bureau of Prisons).
A lack of consistency in integrating effective treatments severely challenges our Nation’s public health and safety agenda to reduce drug abuse and related crime. Therefore, we must provide community organizers, opinion leaders, and policy makers with the tools needed to, once and for all, neutralize the ideological practices that stigmatize substance use disorders, particularly as they affect criminal justice populations.
The combined neuroscientific discoveries of the last two decades give us an unprecedented and detailed view of the risks, processes, and consequences of addiction. From this vantage point, scientists stand ready to test and develop a whole new generation of diverse pharmacotherapeutic agents to combat the devastating effects of drug addiction in more individualized and effective ways. As a result, we find ourselves at the threshold of incredible public health opportunities.
But scientific discovery is not enough. The scope and cost of the effort required to bring any successful new medications to market hinges on the unique synergism that can be generated when public-private partnerships focus on a common goal. In addition, to guarantee the success of such partnerships, we also need to work diligently to optimize the delivery of integrated health care that is responsive to new knowledge and to the particular features that characterize the disease of addiction.
Thank you for this opportunity and I will be pleased to answer any questions you may have.
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Last revised: June 18, 2013