Studies on the dependence-inducing potential of zopiclone and triazolam

Prevalence and correlates of the misuse of z-drugs and benzodiazepines in the National Survey on Drug Use and Health

Background

Benzodiazepines and non-benzodiazepine hypnotics (z-drugs) are commonly prescribed for their anxiolytic and hypnotic properties, though they can also be misused. In studies examining the epidemiology of prescription drug misuse, these medication classes are commonly combined, rendering inadequate knowledge of their patterns of misuse. The objective of this study was to characterize the population prevalence, conditional dependence, and sociodemographic and clinical correlates of the misuse of benzodiazepines and z-drugs.

Methods

Data from the National Survey on Drug Use and Health from 2015 to 2019 were used to estimate population-level prevalence and characteristics of benzodiazepine and z-drug misuse. Groups were derived based on past-year misuse of benzodiazepines alone, z-drugs alone, or both drug types. Unadjusted regression analyses were used to compare groups on characteristics of interest.

Results

Exposure to benzodiazepines and/or z-drugs via prescription or misuse was common; however, only 2% of the population was estimated to have misused a benzodiazepine in the past year, and less than 0.5% misused z-drugs. People who misused only z-drugs were generally older, more likely to have health insurance, more educated, and had less severe psychiatric symptoms. This group was also more likely to report misuse to cope with sleep difficulty. Although concurrent substance use was highly prevalent in all groups, people who misused z-drugs alone generally reported less concurrent substance use than the other groups.

Conclusion

The misuse of z-drugs is less common than benzodiazepines, and people who misuse only z-drugs appear to generally have lower clinical severity. Nonetheless, a substantial subgroup of people exposed to z-drugs report concurrent, past-year use of other substances. Further research on z-drug misuse, including consideration of whether it should be grouped with other anxiolytic/hypnotic drugs, is needed.

Zopiclone: is there any dependence and abuse potential?

Both published and unpublished data concerning the rebound, withdrawal, dependence and abuse potential of zopiclone have been reviewed. As expected for an hypnotic drug of about 5 h elimination half-life, rebound has occasionally been detected but is substantially less frequent than with equivalent benzodiazepines. Tolerance to zopiclone does not occur regularly and cross-tolerance to the benzodiazepines may help in a regimen to withdraw from the latter drugs. Dependence on long-term use, as shown by either a characteristic withdrawal syndrome or by psychological craving, is rare considering the world-wide extent of usage. Abuse (addictive non-medical use) is documented but is also rare, in comparison with the widely abused benzodiazepines. It is concluded that zopiclone has substantial advantages over the benzodiazepines in terms of dependence and abuse potential.

Cyclopyrrolones, unlike some benzodiazepines, do not induce physical dependence in mice

In a model of physical dependence in mice, treatment with cyclopyrrolones such as zopiclone and suriclone (from 4 to 400 mg/kg/day), did not modify the sensitivity of the gamma-aminobutyric acid (GABA) receptor complex to the partial inverse agonist FG 7142 following their withdrawal, whereas sensitivity changes were observed after treatment and withdrawal from some benzodiazepines (e.g. lorazepam, diazepam, flunitrazepam and triazolam). These data suggest that, in contrast to some benzodiazepines, zopiclone and suriclone may not produce physical dependence.

Self-administration of barbiturates and benzodiazepines: a review

Studies of barbiturate and benzodiazepine self-administration are categorized by species and route of administration. Reinforcement, defined as self-administration of drug greater than of a non-drug control, has been demonstrated most often in studies employing the IV route, and there has been greater reliability in this result for a given drug among barbiturates rather than among benzodiazepines. Most studies of PO self-administration in rodents have not demonstrated reinforcement, despite a number of behavioral manipulations to induce drug intake. Studies of PO barbiturate self-administration in monkeys have demonstrated reinforcement but recent studies of PO benzodiazepine self-administration in baboons have not, although physical dependence was demonstrated. Reinforcement via the IG route has not been reliably demonstrated. Behavioral variables, including interreinforcement interval and drug self-administration history, appear to be important determinants of whether or not reinforcement will be demonstrated, particularly among the benzodiazepines; but the range of conditions under which behavioral and pharmacological variables interact to promote or lessen the likelihood of self-administration of these drugs remains to be determined experimentally.

Relative abuse liability of triazolam: experimental assessment in animals and humans

The abuse liability of a drug is a positive, interactive function of the reinforcing and adverse effects of the drug. The relative abuse liability of the hypnotic benzodiazepine, triazolam, has been controversial. This paper reviews animal and human studies bearing on its relative abuse liability, including data on pharmacological profile, reinforcing effects, liking, speed of onset, discriminative stimulus effects, subjective effects, physiological dependence, rebound and early morning insomnia, drug produced anxiety, lethality in overdose, psychomotor impairment, interactions with ethanol, anterograde amnesia, impaired awareness of drug effect, and other psychiatric and behavioral disturbances. It is concluded that the abuse liability of triazolam is less than that of the intermediate duration barbiturates such as pentobarbital. Although there are considerable data indicating similarities of triazolam to other benzodiazepines, there is also substantial speculation among clinical investigators and some limited data suggesting that the abuse liability of triazolam is greater than that of a variety of other benzodiazepines, and virtually no credible data or speculation that it is less. Further research will be necessary to clarify definitively the abuse liability of triazolam relative to other benzodiazepines.