Risk management and post-marketing surveillance for the abuse of medications acting on the central nervous system: expert panel report

Selecting the appropriate hurdles and endpoints for pentilludin, a novel antiaddiction pharmacotherapeutic targeting the receptor type protein tyrosine phosphatase D

Substance use disorders provide challenges for development of effective medications. Use of abused substances is likely initiated, sustained and "quit" by complex brain and pharmacological mechanisms that have both genetic and environmental determinants. Medical utilities of prescribed stimulants and opioids provide complex challenges for prevention: how can we minimize their contribution to substance use disorders while retaining medical benefits for pain, restless leg syndrome, attention deficit hyperactivity disorder, narcolepsy and other indications. Data required to support assessments of reduced abuse liability and resulting regulatory scheduling differs from information required to support licensing of novel prophylactic or therapeutic anti-addiction medications, adding further complexity and challenges. I describe some of these challenges in the context of our current efforts to develop pentilludin as a novel anti-addiction therapeutic for a target that is strongly supported by human and mouse genetic and pharmacologic studies, the receptor type protein tyrosine phosphatase D (PTPRD).

What about "Pharming"? Issues Regarding the Misuse of Prescription and Over-the-Counter Drugs

Recently, a range of prescription and over-the-counter (OTC) drugs have emerged as being used recreationally, either on their own or in combination with other substances, both licit and illicit, including new psychoactive substances (NPS). Among them, the misuse of prescription drugs involves not only traditionally recorded substances, such as benzodiazepines and opioid pain relievers, but also gabapentinoids (e.g., pregabalin and gabapentin); some antidepressants, e.g., bupropion and venlafaxine; some second-generation antipsychotics, e.g., quetiapine and olanzapine. Moreover, the use of some OTC for recreational purposes appears on the increase, especially in vulnerable categories such as young people/youths, including the use of high dosages of the antidiarrheal loperamide; first-generation antihistamines, e.g., promethazine, cyclizine, and diphenhydramine; cough and cold preparations containing dextromethorphan and/or codeine. In this context, the role of the Internet has rapidly increased, playing a significant role both in the diffusion of emerging trends of drug misuse among users and experimenters, and the marketing, sale, and distribution of drugs through online pharmacies. This phenomenon within the context of a rapidly modifying drug scenario is a globally recognized health problem, determining severe adverse consequences, including fatalities, and represents a challenge for clinicians in general, psychiatrists, public health, and drug-control policies.

Abuse of Prescription Drugs in the Context of Novel Psychoactive Substances (NPS): A Systematic Review

Recently, a range of prescription and over-the-counter drugs have been reportedly used as Novel Psychoactive Substances (NPS), due to their potential for abuse resulting from their high dosage/idiosyncratic methods of self-administration. This paper provides a systematic review of the topic, focusing on a range of medications which have emerged as being used recreationally, either on their own or in combination with NPS. Among gabapentinoids, pregabalin may present with higher addictive liability levels than gabapentin, with pregabalin being mostly identified in the context of opioid, polydrug intake. For antidepressants, their dopaminergic, stimulant-like, bupropion activities may explain their recreational value and diversion from the therapeutic intended use. In some vulnerable clients, a high dosage of venlafaxine (‘baby ecstasy’) is ingested for recreational purposes, whilst the occurrence of a clinically-relevant withdrawal syndrome may be a significant issue for all venlafaxine-treated patients. Considering second generation antipsychotics, olanzapine appears to be ingested at very large dosages as an ‘ideal trip terminator’, whilst the immediate-release quetiapine formulation may possess proper abuse liability levels. Within the image- and performance- enhancing drugs (IPEDs) group, the beta-2 agonist clenbuterol (‘size zero pill’) is reported to be self-administered for aggressive slimming purposes. Finally, high/very high dosage ingestion of the antidiarrhoeal loperamide has shown recent increasing levels of popularity due to its central recreational, anti-withdrawal, opiatergic effects. The emerging abuse of prescription drugs within the context of a rapidly modifying drug scenario represents a challenge for psychiatry, public health and drug-control policies.

Psychedelics: Where we are now, why we got here, what we must do

The purpose of this commentary is to provide an introduction to this special issue of Neuropharmacology with a historical perspective of psychedelic drug research, their use in psychiatric disorders, research-restricting regulatory controls, and their recent emergence as potential breakthrough therapies for several brain-related disorders. It begins with the discovery of lysergic acid diethylamide (LSD) and its promising development as a treatment for several types of mental illnesses during the 1940s. This was followed by its abuse and stigmatization in the 1960s that ultimately led to the placement of LSD and other psychedelic drugs into the most restrictively regulated drug schedule of the United States Controlled Substances Act (Schedule I) in 1970 and its international counterparts. These regulatory controls severely constrained development of psychedelic substances and their potential for clinical research in psychiatric disorders. Despite the limitations, there was continued research into brain mechanisms of action for psychedelic drugs with potential clinical applications which began during the 1990s and early 2000s. Finding pathways to accelerate clinical research in psychedelic drug development is supported by the growing body of research findings that are documented throughout this special issue of Neuropharmacology. Accumulated research to date suggests psychedelic drug assisted psychotherapy may emerge as a potential breakthrough treatment for several types of mental illnesses including depression, anxiety, post-traumatic stress disorder, and addiction that are refractory to current evidenced based therapies. This research equally shows promise in advancing the understanding of the brain, brain related functioning, and the consequential effects of untreated brain related diseases that have been implicated in causing and/or exacerbating numerous physical disease state conditions. The authors conclude that more must be done to effectively address mental illnesses and brain related diseases which have become so pervasive, destructive, and whose treatments are becoming increasingly resistant to current evidenced based therapies. This article is part of the Special Issue entitled 'Psychedelics: New Doors, Altered Perceptions'.

Phenprobamate dependence: a case report

Phenprobamate (3-phenylpropylcarbamate) is a centrally acting muscle relaxant with mild sedative and anticonvulsant effects. Muscle relaxants can enhance and prolong the effect of narcotic drugs and enable to obtain same effect with a smaller amount of alcohol or illicit substance. Almost all of the centrally acting muscle relaxants have varying sedative effects on which their abuse potential mainly depends. Data related to abuse of carisoprodol, meprobamate, baclofen takes place in the literature. However, to our knowledge this is the first case report about abuse of and tolerance to phenprobamate. We aimed to attract attention to important points of prescribing drugs that have abuse potential like in our case who was using up to 16000 mg/day phenprobamate.

Assessment of the abuse liability of a dual orexin receptor antagonist: a crossover study of almorexant and zolpidem in recreational drug users

BACKGROUND

Dual orexin receptor antagonists (DORAs) enable initiation and maintenance of sleep in patients with primary insomnia. Blockade of the orexin system has shown reduction of drug-seeking behavior in animal studies, supporting the role of orexin antagonism as a novel approach for treating substance abuse. Since hypnotics are traditionally associated with misuse, a lack of abuse liability of DORAs would offer significant benefits over current therapies for sleep disorders.

METHODS

In this randomized, crossover, proof-of-concept study, single oral doses of the DORA almorexant (200, 400, and 1,000 mg) were administered to healthy subjects with previous non-therapeutic experience with central nervous system depressants and were compared with placebo and single oral doses of zolpidem (20 and 40 mg), a benzodiazepine-like drug. Subjective measures of abuse potential (visual analog scales [VAS], Addiction Research Center Inventory, and Subjective Drug Value) and objective measures (divided attention [DA]) were evaluated over 24 h post-dose in 33 evaluable subjects.

RESULTS

Drug Liking VAS peak effect (E max; primary endpoint) was significantly higher for all doses of almorexant and zolpidem compared with placebo (p<0.001). Almorexant 200 mg showed significantly less 'Drug Liking' than both zolpidem doses (p<0.01), and almorexant 400 mg had smaller effects than zolpidem 20 mg (p<0.05), while almorexant 1,000 mg was not different from either zolpidem dose. Results were similar for other subjective measures, although almorexant generally showed smaller negative and perceptual effects compared with zolpidem. Almorexant also showed less cognitive impairment compared with zolpidem on most DA endpoints.

CONCLUSION

This study in humans investigating single doses of almorexant is the first to explore and show abuse liability of a DORA, a class of compounds that is not only promising for the treatment of sleep disorders, but also of addiction.

Attractiveness of reformulated OxyContin(R) tablets: assessing comparative preferences and tampering potential

Reformulated OxyContin® (oxycodone HCl controlled-release or ORF) was developed as a tamper and abuse-deterrent product, to reduce the risk of product abuse, misuse and their consequences. This noninterventional single-session study asked participants who were medically-healthy recreational opioid users, aged 18 years and older, to consider how they would use commonly available supplies to tamper with placebo ORF and placebo original OxyContin (OC) tablets, and how they would assess the attractiveness of tampering and abusing ORF tablets, as compared with other opioid formulations. Participants provided information on past opioid use, and they assessed the properties of five nonhypothetical oxycodone products and two hypothetical oxycodone products. Participants provided feedback on tampering preferences, preferred tamper methods for each product, overall tampering potential and product preferences. We had 30 participants (27 males and 3 females; mean age 35 years, range 18-51) complete both the interview and tampering sessions. Participants judged OC as the most attractive, valuable, desirable and most likely to be tampered with, from among all opioid products studied. By contrast, they rated ORF as the least attractive, least valuable, least desirable, and least likely to be tampered with among all the nonhypothetical opioid products studied. These results suggested that recreational drug abusers view ORF tablets as tamper-deterrent products.

Postmarketing surveillance for "modified-risk" tobacco products

INTRODUCTION

The U.S. Food and Drug Administration (FDA) acquired authority to regulate tobacco products in 2009. This authority will provide a structured process for manufacturers to introduce products that may have "modified-risk" for morbidity or mortality relative to traditional tobacco products, with postmarketing surveillance and studies a condition of marketing.

METHOD

A narrative review approach was taken. The author searched and integrated publicly accessible literature on tobacco product surveillance as well as drug and medical device postmarket activities currently performed by FDA.

RESULTS

FDA relies on active and passive methods for postmarket surveillance and can require specific studies and risk evaluation and mitigation strategies for certain products, including those with abuse liability. Past efforts at examining the individual and population effects of reduced harm tobacco products provide an example of integrating different data streams.

DISCUSSION

Postmarket surveillance can be viewed in terms of the Agent-Host-Vector-Environment model, and concepts from diffusion of innovations are relevant to understanding factors associated with the adoption of new products by the population. Given that active and passive surveillance approaches have different strengths and weaknesses, multiple approaches may be necessary to evaluate population-level effects. Assuring that required studies are properly conducted and reported and that data indicating significant public health harms are quickly recognized will be important going forward.

CONCLUSIONS

The advent of broad regulatory authority over tobacco provides opportunities for policy evaluation research. The research community can provide FDA with the independent science it needs to evaluate the public health impact of novel tobacco products.

When drugs in the same controlled substance schedule differ in real-world abuse, should they be differentiated in labeling?

The prescription drugs regulated in the most restrictive controlled substance schedule for those with an approved therapeutic use vary widely in their real world risk of abuse and harm. Opioid analgesics have the highest rates of abuse, overdose death, drug abuse treatment needs and societal costs in comparison to other Schedule II drugs. Stimulants for attention-deficit/hyperactivity disorders (ADHD) account for substantially lower rates of abuse, harm, and public health impact. The scheduling of drugs is determined by the World Health Organization, the United States Food and Drug Administration, and other regulatory agencies, through a quasi-public process that relies heavily on pre-marketing studies that are conducted in highly controlled clinical settings. We propose that it is increasingly in the interest of science-based regulation and public health to recognize and communicate differences among drugs based on their real-world abuse and public health harm using surveillance data. Appropriate differentiation through labeling of drugs that will likely remain in the same schedule could provide powerful incentives for drug development and research, would aid prescriber/patient decision making by informing them of real differences across drugs within a schedule, and may also contribute to public health efforts to reduce drug abuse. There are risks of course, that include inadvertent perceptions that drugs labeled to be lower in risk are not taken as seriously as others in the same category. Challenges such as these, however, can be overcome and should not serve as barriers to objective communications regarding a drug's actual risks.

[Post-marketing surveillance systems for psychoactive prescription drug abuse]

Drugs affecting the central nervous system form a unique group of products for surveillance because they could be misused, abused or diverted. Considering the characteristics of this behaviour that is often concealed, specific post-marketing surveillance systems have been developed to monitor abuse of prescription drugs in some countries. The purpose of this review is to list and to describe post-marketing surveillance systems, according their methodology, in France and in foreign countries. These programs are based on adverse effect notifications, medical or legal consequences of abuse, general or specific population-based survey, professional networks or medication databases. Some programs use simultaneously several information sources. In conclusion, the multifaceted nature, the diversity and the inventiveness of post-marketing surveillance systems reflects the complexity of the abuse issue.

Conference on abuse liability and appeal of tobacco products: conclusions and recommendations

The rate of initiation and progression to dependence and premature mortality are higher for tobacco products than for any other dependence producing substance. This is not explained simply by the addictiveness ("abuse liability") or by enticing product designs ("product appeal") alone, but rather by both of these factors in combination with marketing and social influences that also influence "product appeal". A working meeting of leading experts in abuse liability (AL) and product appeal was convened to examine how these disciplines could be more effectively applied to the evaluation of tobacco products for the purposes of regulation that would include setting standards for designs and contents intended to reduce the risk of initiation and dependence. It was concluded that abuse liability assessment (ALA) is a validated approach to testing pharmaceutical products but has not been extensively applied to tobacco products: such application has demonstrated feasibility, but special challenges include the diverse range of products, product complexity, and the absence of satisfactory placebo products. Consumer testing for product appeal is widely used by consumer product marketers as well as by researchers in their efforts to understand consumer product preferences and use but has not been extensively applied to tobacco products except by the tobacco industry. Recommendations for testing, methods development, and research were developed. A major recommendation was that tobacco products should be tested for AL and product appeal, and the results integrated and evaluated so as to more accurately predict risk of initiation, dependence, and persistence of use.

Multiple Determinants of Specific Modes of Prescription Opioid Diversion

Numerous national surveys and surveillance programs have shown a substantial rise in the abuse of prescription opioids over the past 15 years. Accessibility of these drugs to non-patients is the result of their unlawful channeling from legal sources to the illicit marketplace (diversion). Empirical data on diversion remain absent from the literature. This paper examines abusers' sources of diverted drugs from two large studies: 1) a national sample of opioid treatment clients (N=1983), and 2) a South Florida study targeting diverse populations of opioid abusers (N=782). The most common sources of diverted medications were dealers, sharing/trading, legitimate medical practice (e.g., unknowing medical providers), illegitimate medical practice (e.g., pill mills), and theft, in that order. Sources varied by users' age, gender, ethnicity, risk-aversiveness, primary opioid of abuse, injection drug use, physical health, drug dependence, and either access to health insurance or relative financial wealth. Implications for prescription drug control policy are discussed.

Electronic nicotine delivery systems: a research agenda

Electronic nicotine delivery systems (ENDS, also called electronic cigarettes or e-cigarettes) are marketed to deliver nicotine and sometimes other substances by inhalation. Some tobacco smokers report that they used ENDS as a smoking cessation aid. Whether sold as tobacco products or drug delivery devices, these products need to be regulated, and thus far, across countries and states, there has been a wide range of regulatory responses ranging from no regulation to complete bans. The empirical basis for these regulatory decisions is uncertain, and more research on ENDS must be conducted in order to ensure that the decisions of regulators, health care providers and consumers are based on science. However, there is a dearth of scientific research on these products, including safety, abuse liability and efficacy for smoking cessation. The authors, who cover a broad range of scientific expertise, from basic science to public health, suggest research priorities for non-clinical, clinical and public health studies. They conclude that the first priority is to characterize the safety profile of these products, including in long-term users. If these products are demonstrated to be safe, their efficacy as smoking cessation aids should then be tested in appropriately designed trials. Until these studies are conducted, continued marketing constitutes an uncontrolled experiment and the primary outcome measure, poorly assessed, is user health. Potentially, this research effort, contributing to the safety and efficacy of new smoking cessation devices and to the withdrawal of dangerous products, could save many lives.

Risk management and post-marketing surveillance of CNS drugs

Drugs affecting the central nervous system span a broad range of chemical entities, dosage forms, indications, and risks. Unintended consequences include potential abuse and overdose in non-patient drug abusers, deliberate tampering of drug dosage forms, and criminal behavior associated with diversion. Regulators must consider diverse factors to find the appropriate conditions of approval to minimize unintended consequences while enabling a level of access desired by health care providers and patients. This commentary appears as part of a special issue of Drug and Alcohol Dependence that focuses on risk management and post-marketing surveillance and addresses key issues that pose real-world challenges to pharmaceutical sponsors and regulators in particular. For example, in the U.S., Controlled Substances Act drug scheduling can be considered a risk management strategy but its legal authorities and administrative processes are independent from those of risk management (including Risk Evaluation and Mitigation Strategies or REMS); better harmonization of these approaches is vital from drug development and regulatory perspectives. Risk management would ideally be implemented on a strong science foundation demonstrating that the tools employed to mitigate risks and ensure safe use are effective. In reality, research and evaluation of tools in this area is in its infancy and will necessarily be an evolutionary process; furthermore, there is little precedent for linking interventions and program evolution to unintended consequences such as regional outbreaks of abuse and diversion. How such issues are resolved has the potential to stimulate or stifle innovations in drug development and advance or imperil health care.

Abuse liability assessment of tobacco products including potential reduced exposure products

The harm produced by tobacco products is a result of frequent use of a highly toxic product. Reducing the adverse public health impact of tobacco products might be most effectively achieved by reducing the likelihood of their use and the toxicity of the products. Products that retain some characteristics of cigarettes but have been altered with the intention of reducing toxicity have been referred to as modified risk tobacco products or potential reduced exposure products (MRTP/PREP). Evaluation of their content, emission, and toxicity is discussed in other articles in this special issue. Here, we discuss the methodology that has been used to examine the likelihood of abuse or addiction. Abuse liability assessment (ALA) methodology has been used by the Food and Drug Administration (FDA) and other drug regulatory agencies world-wide for decades to assess the risks posed by a wide variety of pharmacologically active substances. ALA is routinely required among other evaluations of safety during the pre-market assessment of new drugs, and is continually adapted to meet the challenges posed by new drug classes and drug formulations. In the 2009 law giving FDA regulation over tobacco products, FDA is now required to evaluate new tobacco products including MRTP/PREPs to determine their risk for abuse and toxicity at the population level. This article describes the traditional tools and methods of ALA that can be used to evaluate new tobacco and nicotine products including MRTP/PREPs. Such ALA data could contribute to the scientific foundation on which future public policy decisions are based.

Case histories in pharmaceutical risk management

The development and implementation of programs in the U.S. to minimize risks and assess unintended consequences of new medications has been increasingly required by the Food and Drug Administration (FDA) since the mid 1990s. This paper provides four case histories of risk management and post-marketing surveillance programs utilized recently to address problems associated with possible abuse, dependence and diversion. The pharmaceutical sponsors of each of these drugs were invited to present their programs and followed a similar template for their summaries that are included in this article. The drugs and presenting companies were OxyContin, an analgesic marketed by Purdue Pharma L.P., Daytrana and Vyvanse, ADHD medications marketed by Shire Pharmaceuticals, Xyrem for narcolepsy marketed by Jazz Pharmaceuticals, and Subutex and Suboxone for opioid dependence marketed by Reckitt Benckiser Pharmaceuticals Inc. These case histories and subsequent discussions provide invaluable real-world examples and illustrate both the promise of risk management programs in providing a path to market and/or for keeping on the market drugs with serious potential risks. They also illustrate the limitations of such programs in actually controlling unintended consequences, as well as the challenge of finding the right balance of reducing risks without posing undue barriers to patient access. These experiences are highly relevant as the FDA increasingly requires pharmaceutical sponsors to develop and implement the more formalized and enforceable versions of the risk management term Risk Evaluation and Mitigation Strategies (REMS).