Estimation of clonazepam abuse liability: a new method using a reimbursed drug database

Clonazepam: Indications, Side Effects, and Potential for Nonmedical Use

After participating in this activity, learners should be better able to:• Assess the misuse potential of clonazepam• Characterize the nonmedical use of clonazepam• Identify the health problems associated with long-term use of clonazepam ABSTRACT: Clonazepam, a benzodiazepine, is commonly used in treating various conditions, including anxiety disorders and epileptic seizures. Due to its low price and easy availability, however, it has become a commonly misused medication, both in medical and recreational contexts. In this review, we aim to highlight the behavioral and pharmacological aspects of clonazepam and its history following its approval for human use. We examine the circumstances commonly associated with the nonmedical use of clonazepam and raise points of particular concern. Clonazepam, alone or in combination with other psychoactive substances, can lead to unwanted effects on health, such as motor and cognitive impairment, sleep disorders, and aggravation of mood and anxiety disorders. Prolonged use of clonazepam may lead to physical dependence and tolerance. There is therefore a need to find safer therapeutic alternatives for treating seizures and anxiety disorders. Greater awareness of its frequent nonmedical use is also needed to achieve safer overall use of this medication.

Combating escalating harms associated with pharmaceutical opioid use in Australia: the POPPY II study protocol

INTRODUCTION

Opioid prescribing has increased 15-fold in Australia in the past two decades, alongside increases in a range of opioid-related harms such as opioid dependence and overdose. However, despite concerns about increasing opioid use, extramedical use and harms, there is a lack of population-level evidence about the drivers of long-term prescribed opioid use, dependence, overdose and other harms.

METHODS AND ANALYSIS

We will form a cohort of all adult residents in New South Wales (NSW), Australia, who initiated prescribed opioids from 2002 using Pharmaceutical Benefits Scheme dispensing records. This cohort will be linked to a wide range of other datasets containing information on sociodemographic and clinical characteristics, health service use and adverse outcomes (eg, opioid dependence and non-fatal and fatal overdose). Analyses will initially examine patterns and predictors of prescribed opioid use and then apply regression and survival analysis to quantify the risks and risk factors of adverse outcomes associated with prescribed opioid use.

ETHICS AND DISSEMINATION

This study has received full ethical approval from the Australian Institute of Health and Welfare Ethics Committee, the NSW Population and Health Services Research Committee and the ACT Health Human Research Ethics Committee. This will be the largest postmarketing surveillance study of prescribed opioids undertaken in Australia, linking exposure and outcomes and examining risk factors for adverse outcomes of prescribed opioids. As such, this work has important translational promise, with direct relevance to regulatory authorities and agencies worldwide. Project findings will be disseminated at scientific conferences and in peer-reviewed journals. We will also conduct targeted dissemination with policy makers, professional bodies and peak bodies in the pain, medicine and addiction fields through stakeholder workshops and advisory groups. Results will be reported in accordance with the REporting of studies Conducted using Observational Routinely collected Data (RECORD) Statement.

Antidepressant adherence patterns in older patients: use of a clustering method on a prescription database

According to the World Health Organization, depression will become the second most important cause of disability worldwide by 2020. Our objective was to identify patterns of adherence to antidepressant treatments in older patients using several indicators of adherence and to characterize these patterns in terms of medication exposure. We conducted a retrospective cohort study using the French National Health Insurance reimbursement database. Incident antidepressant users aged more than 65 were included from July 1, 2010, to June 30, 2011, and followed up for 18 months. Antidepressant and other psychotropic drugs (opioids, benzodiazepines, antipsychotics, anti-epileptics) were recorded. Adherence to antidepressant treatment was assessed by several measures including proportion of days covered, discontinuation periods, persistence of treatment, and doses dispensed. Patients were classified according to their adherence patterns using a mixed clustering method. We identified five groups according to antidepressant adherence. One group (n = 7505, 26.9%) was fully adherent with regard to guidelines on antidepressant use. Two patterns of nonadherent users were identified: irregular but persistent users (n = 5131, 18.4%) and regular but nonpersistent users (n = 9037, 32.4%). Serotonin reuptake inhibitors were the most frequently dispensed antidepressant class (70.6%), followed by other antidepressants (43.3%, mainly serotonin-norepinephrine reuptake inhibitors and tianeptine) and tricyclic antidepressants (TCAs) (13.4%). Nonadherent users more frequently had a dispensing of TCA, opioid, and anti-epileptic medication than adherent users. Health policies to improve adherence to antidepressant treatment may require better training of physicians and pharmacists, insisting on the important role of the continuation period of antidepressant treatment.

Harmonizing post-market surveillance of prescription drug misuse: a systematic review of observational studies using routinely collected data (2000-2013)

BACKGROUND

Prescription drug misuse is a growing public health concern globally. Routinely collected data provide a valuable tool for quantifying prescription drug misuse.

OBJECTIVE

To synthesize the global literature investigating prescription drug misuse utilizing routinely collected, person-level prescription/dispensing data to examine reported measures, documented extent of misuse and associated factors.

METHODS

The MEDLINE, EMBASE, CINAHL, MEDLINE In Process, Scopus citations and Google Scholar databases were searched for relevant articles published between 1 January 2000 and 31 July 2013. A total of 10,803 abstracts were screened and 281 full-text manuscripts were retrieved. Fifty-two peer-reviewed, English-language manuscripts met our inclusion criteria-an aim/method investigating prescription drug misuse in adults and a measure of misuse derived exclusively from prescription/dispensing data.

RESULTS

Four proxies of prescription drug misuse were commonly used across studies: number of prescribers, number of dispensing pharmacies, early refills and volume of drugs dispensed. Overall, 89 unique measures of misuse were identified across the 52 studies, reflecting the heterogeneity in how measures are constructed: single or composite; different thresholds, cohort definitions and time period of assessment. Consequently, it was not possible to make definitive comparisons about the extent (range reported 0.01-93.5 %), variations and factors associated with prescription drug misuse.

CONCLUSIONS

Routine data collections are relatively consistent across jurisdictions. Despite the heterogeneity of the current literature, our review identifies the capacity to develop universally accepted metrics of misuse applied to a core set of variables in prescription/dispensing claims. Our timely recommendations have the potential to unify the global research field and increase the capacity for routine surveillance of prescription drug misuse.

Deviant patterns of methylphenidate use in adults: a Danish nationwide registry-based drug utilization study

PURPOSE

Several survey studies have documented misuse of methylphenidate defined as the use of non-prescribed methylphenidate or use different from what was prescribed. We aimed to identify and characterize adults with deviant patterns of methylphenidate use in Denmark during 2007-2012. Further, we aimed to identify risk factors associated with deviant patterns of use.

METHODS

Based on individual-level prescription data, new users of methylphenidate were followed for one year after filling their first prescription on methylphenidate. Adult patients were identified with deviant patterns of use if they had ≥4 different prescribers and filled ≥1095 defined daily doses of methylphenidate during the year of follow-up. Risk factors were estimated by using logistic regression.

RESULTS

Among 20 829 new users of methylphenidate, we identified 82 (0.39%) patients displaying deviant patterns of use. Characteristics associated with deviant patterns of use included an initial prescription for extended-release methylphenidate (OR2 4.35), age 25-49 years at first prescription (OR2 2.49), general practitioners or hospital doctors as initial prescribers (OR2 3.06 and OR2 4.07) and prior use of drugs used in addictive disorders (OR2 2.08) or opioids (OR2 1.75). Sensitivity analyses revealed that the number of different prescribers alone does not seem to effectively identify deviant users of methylphenidate.

CONCLUSION

We have identified characteristics associated with deviant patterns of methylphenidate use. Our results do not allow us to conclude if deviant users truly represent medical misusers.

Estimated magnitude of diversion and abuse of opioids relative to benzodiazepines in France

INTRODUCTION

Prescription drug abuse is a major concern in several countries. France appears to be particularly prone to the abuse of opiate maintenance treatment (OMT) opioids and benzodiazepines (BZD), whereas the abuse of opioid analgesics (OA) is less commonly reported. To estimate the extent of psychoactive drug abuse, the French drug agency relies on different methods measuring various diversion indicators used as proxies for the detection of abuse/misuse: suspicion of abuse/dependence, illegal acquisition by patients seen in specialized care centers, prescription forgery and doctor shopping. The main objectives of the present study are to analyse the abuse and diversion of opioids (both OA and OMT), in comparison with those of BZDs, through the concurrent use of three different data sources.

METHODS

Diversion and abuse of opioids were analysed using indicators of abuse and diversion derived from three data sources over the period 2006-2008. Then, opioids were compared to BZDs for the year 2008 using the same indicators.

RESULTS

The analysis suggests that BZDs are more commonly dispensed than OAs and OMTs but that abuse and diversion are related mainly to OMT (particularly to buprenorphine), morphine and BZDs and less to OAs (except for morphine).

CONCLUSION

This study presents an original approach, based on the use of multiple data sources, to evaluate and compare the estimated abuse and diversion of opioids and benzodiazepines. It provides health authorities with a global, comparative and summarized overall view of the importance of different patterns of diversion and abuse for different prescription drugs.

High dose benzodiazepine dependence: description of 29 patients treated with flumazenil infusion and stabilised with clonazepam

The withdrawal syndrome from benzodiazepine (BZD) can be severe and in some cases may impede cessation of the use of the drug. We present here a case series of benzodiazepine detoxification by flumazenil infusion, stabilised with clonazepam. Patients were treated with flumazenil 1.35 mg/day for a median of 7 days. Self-reported physical withdrawal symptoms were recorded daily. In addition to flumazenil, antidepressants were given before treatment commenced and clonazepam was administered nightly with both being continued after discharge. Twenty-nine patients were treated. No patients dropped out from the treatment programme. Nine patients (31%) required a temporary reduction/cessation of the infusion. The linear trend in the reduction of the daily withdrawal scores in the overall study population was significant. The linear trends were also significant in the group of patients for whom a temporary reduction/suspension of the flumazenil was required. Six months after treatment, 15 patients (53%) were abstinent from clonazepam and other BZDs. For five (21%) the BZD dependence were reinstated. More than two-thirds of the subjects tolerated the procedure well and about half had a good long term response. Slow flumazenil infusion appears to merit consideration as a possible future treatment. Suggestions for future research are examined.

[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.

Patterns of methylphenidate use and assessment of its abuse and diversion in two French administrative areas using a proxy of deviant behaviour determined from a reimbursement database: main trends from 2005 to 2008

BACKGROUND

Methylphenidate is a psychostimulant drug indicated for the treatment of attention-deficit hyperactivity disorder (ADHD). Its abuse and diversion have been previously described in specific populations, such as students; however, few studies investigating abuse and diversion among the overall population are available.

OBJECTIVES

The aim of this study was to describe patterns of methylphenidate use and to explore the magnitude of its abuse and diversion in two French administrative areas using data from a reimbursement database. A proxy of 'deviant behaviour' was used for the abuse and diversion of methylphenidate, defined using the following parameters: total number of defined daily doses (DDDs) of methylphenidate dispensed; number of different pharmacies seen for dispensing of methylphenidate; number of prescribers consulted for a prescription of methylphenidate; and number of dispensings of methylphenidate. Data from the reimbursement database were analysed by clustering methods. These data were assessed from 2005 to 2008.

METHOD

The French General Health Insurance System (GHIS) database was used to obtain data on methylphenidate use in two French administrative areas. Individuals affiliated to the GHIS who had a prescription for methylphenidate reimbursed between 1 January and 31 March of 4 selected years (2005, 2006, 2007 and 2008) were included. After the first dispensing of methylphenidate for these individuals, all their dispensings (including methylphenidate and other psychoactive drugs) were monitored over a 9-month period. Following a descriptive analysis, a clustering method was used to identify different subgroups of subjects according to the methylphenidate consumer profile characteristics.

RESULTS

With regard to the number of patients who had a dispensing for methylphenidate during the first quarter of the year, an 84% increase was observed between 2005 (n = 640) and 2008 (n = 1175). The clustering method identified two subgroups. One of them was characterized by a higher number of dispensings, different prescribers and pharmacies and a greater total dispensed quantity, suggesting a deviant behaviour and, thus, possible abuse and diversion of methylphenidate. These subjects were older (aged 35.4 ± 11.3 years) and were more frequently patients receiving benzodiazepines, antidepressants, antipsychotics and maintenance opioid treatment. The proportion of subjects with a deviant behaviour increased from 0.5% in 2005 to 2% in 2007 and then decreased to 1.2% in 2008.

CONCLUSION

This method was able to assess the magnitude of methylphenidate abuse liability and to follow its evolution. The decrease in methylphenidate abuse and diversion seen between 2007 and 2008 can be explained by the enactment in April 2008 of specific regulations for prescription drugs (such as methylphenidate) that are deemed by the French government to have the potential for misuse; these regulations require the establishment of a 'contract of care' between the GHIS, prescriber and patient.

Which indicators can public health authorities use to monitor prescription drug abuse and evaluate the impact of regulatory measures? Controlling High Dosage Buprenorphine abuse

BACKGROUND

Two methods have been recently developed from a drug reimbursement database to provide useful indicators for public health authorities concerning the abuse potential of psychotropic drugs. The doctor-shopping indicator (DSI) measures the proportion of the drug obtained by doctor shopping among the overall quantity of the drug reimbursed and the clustering method reveals subgroups of deviant patients.

OBJECTIVE

The objective of the study was to analyze and compare indicators resulting from these two methods, applied to High Dosage Buprenorphine (HDB) (a product well-known to be diverted in France), in order to determine which public health authorities needs they answer.

DATA ANALYSIS

The patients with reimbursed HDB were grouped using the clustering method in terms of drug dispensations characteristics over a nine month period. The characteristics of the resulting subgroups, including their DSI, were then compared.

RESULTS

4787 Patients (73.4%) had no measurable doctor-shopping behaviour. But the comparison of the two methods demonstrated that the more a patient's profile was characterized by deviant behavior, the higher was the DSI: from 0.4% in a subgroup with a median profile to 72% in a subgroup with a deviant profile.

CONCLUSION

These two methods are useful surveillance tools for public health authorities: the clustering method may help devise pertinent intervention strategies to reduce prescription drug abuse while the DSI method provides quantitative information demonstrating whether these strategies are useful. We discuss the advantages and disadvantages of using these two methods as useful indicators for public health authorities.

Evidence of clonazepam abuse liability: results of the tools developed by the French Centers for Evaluation and Information on Pharmacodependence (CEIP) network

Recent observations suggest the existence of clonazepam abuse. To determine its importance in France, a quantitative and systematic synthesis of all clonazepam data of several epidemiological tools of the Centers for Evaluation and Information on Pharmacodependence (CEIP) network has been performed in comparison with data on others benzodiazepines (BZD). Data on clonazepam and other BZD have been analysed from different epidemiological tools: OSIAP survey that identifies drugs obtained by means of falsified prescriptions, Observation of Illegal Drugs and Misuse of Psychotropic Medications (OPPIDUM) survey that describes modalities of use and data from regional French health reimbursement system. In OSIAP survey, the proportion of clonazepam falsified prescriptions among all BZD falsified prescriptions increased. During the 2006 OPPIDUM survey, the analysis of the BZD modalities of use highlights clonazepam abuse liability (for example 23% of illegal acquisition), in second rank after flunitrazepam. Studies based on data from the French health reimbursed system show that 1.5% of subjects with clonazepam dispensing had a deviant behaviour. Among BZD, clonazepam has the second most important doctor-shopping indicator (3%) after flunitrazepam. All these data provide some arguments in favour of clonazepam abuse liability in real life and the necessity to reinforce its monitoring.