Benzodiazepine discontinuation syndromes

Evaluation of safety and side effects in the process of anti-anxiety drug development *

As with other drugs it is necessary to look for changes induced by anxiolytics on vital signs, laboratory parameters and adverse events. In return, in a more specific way for anxiolytics, we will look at side effects at the central nervous system level with psychological and physiological battery tests. We will also assess the safety of use of anxiolytics in certain specific conditions, such as overdose or withdrawal and in certain populations such as the elderly, neonates and children. The assessment of safety and side effects, whatever the drug type studied, must come early in the developing process of a drug (phases I, II and III).

Selective serotonin reuptake inhibitors and benzodiazepines in panic disorder: A meta-analysis of common side effects in acute treatment

BACKGROUND

Benzodiazepines (BZs) and selective serotonin reuptake inhibitors (SSRIs) are effective in the pharmacologic treatment of panic disorder (PD). However, treatment guidelines favor SSRIs over BZs based on the belief that BZs are associated with more adverse effects than SSRIs. This belief, however, is currently supported only by opinion and anecdotes.

AIM

The aim of this review and meta-analysis was to determine if there truly is evidence that BZs cause more adverse effects than SSRIs in acute PD treatment.

METHODS

We systematically searched Web of Science, PubMed, Cochrane Central Register of Controlled Trials, and clinical trials register databases. Short randomized clinical trials of a minimum of four weeks and a maximum of 12 weeks that studied SSRIs or BZs compared to placebo in acute PD treatment were included in a meta-analysis. The primary outcome was all-cause adverse event rate in participants who received SSRIs, BZs, or placebo.

RESULTS

Overall, the meta-analysis showed that SSRIs cause more adverse events than BZs in short-term PD treatment. Specifically, SSRI treatment was a risk factor for diaphoresis, fatigue, nausea, diarrhea, and insomnia, whereas BZ treatment was a risk factor for memory problems, constipation, and dry mouth. Both classes of drugs were associated with somnolence. SSRIs were associated with abnormal ejaculation, while BZs were associated with libido reduction. BZs were protective against tachycardia, diaphoresis, fatigue, and insomnia.

CONCLUSION

Randomized, blinded studies comparing SSRIs and BZs for the short-term treatment of PD should be performed. Clinical guidelines based on incontrovertible evidence are needed.

Ethosuximide Reduces Mortality and Seizure Severity in Response to Pentylenetetrazole Treatment During Ethanol Withdrawal

AIMS

We recently demonstrated that T-type calcium channels are affected by alcohol abuse and withdrawal. Treatment with ethosuximide, an antiepileptic drug that blocks T-type calcium channels, reduces seizure activity induced by intermittent ethanol exposures and withdrawals. Here, we expand on these findings to test whether ethosuximide can reduce the sensitivity to pentylenetetrazole-induced seizures during ethanol withdrawal.

METHODS

We used an intermittent ethanol exposure model to produce withdrawal-induced hyperexcitability in DBA/2J mice.

RESULTS

Ethosuximide (250 mg/kg) reduced seizure severity in mice undergoing ethanol withdrawal with concurrent PTZ treatment (20 mg/kg). Importantly, ethosuximide did not produce rebound excitability and protected against ethanol withdrawal-induced mortality produced by concurrent PTZ treatment (40 mg/kg).

CONCLUSION

These results, in addition to previous preclinical findings, suggest that ethosuximide should be further evaluated as a safe, effective alternative to benzodiazepines for the treatment of alcohol withdrawal.

Benzodiazepine ligands rapidly influence GABAA receptor diffusion and clustering at hippocampal inhibitory synapses

Benzodiazepines (BZDs) are widely used in the treatment of a variety of neurological and psychiatric conditions including anxiety, insomnia and epilepsy. BZDs are thought to act predominantly by affecting the gating of GABAA receptor channels, resulting in enhanced GABA-mediated currents in neurons. However, mutations mimicking the effect of BZDs on GABAAR channel gating have been shown to also impact the membrane dynamics and synaptic anchoring of the receptors. Here, using single molecule tracking combined with electrophysiological recordings, we show that BZD ligands rapidly influence the dynamic behavior of GABAARs in hippocampal neurons. Application of the inverse BZD agonist DMCM rapidly increased the diffusion and reduced the clustering of GABAARs at synapses, resulting in reduced postsynaptic currents. Conversely, the BZD full agonist diazepam had little effect at rest but reduced lateral diffusion and increased synaptic stabilization and clustering of GABAARs upon sustained neuronal activity, resulting in enhanced potency of inhibitory synapses. These effects occurred in the absence of detectable changes in gephyrin clusters, suggesting they did not reflect a rapid dispersion of the synaptic scaffold. Thus, alterations of the diffusion and synaptic anchoring of GABAARs represent a novel, unsuspected mechanism through which BZDs rapidly modulate GABA signaling in central neurons.

Medication dependence and anxiety

Anxiety disorders are common and costly psychiatric illnesses. Pharmacological treatment was enhanced with the introduction of benzodiazepines, which proved safer and more effective than older drugs. The risk of dependence, however, has made clinicians reluctant to use these medications. In fact, few patients appear to develop significant difficulties with these drugs, given how widely they are used. Careful planning for discontinuation of therapy is important. In addition, for some individuals, there appears to be a complex and as yet unelucidaied relationship between dependence on drugs or alcohol and anxiety. The newer antidepressants offer efficacy without abuse or dependence liability, but are expensive and have side effects that are intolerable for some patients. Pharmacological therapy for anxiety should be prescribed and managed so as to minimize any existing risk, while aiming to restore the patient to wellness in terms of symptoms and function.

Treatment with haloperidol and diazepam alters GABA(A) receptor density in the rat brain

A significant body of data suggests that GABA(A) receptors are altered in the CNS of subjects with schizophrenia. However, subjects with schizophrenia are treated with antipsychotic drugs and, in some cases, antipsychotic drugs and benzodiazepines. It has therefore been suggested that the changes in GABA(A) receptors in the CNS of subjects with schizophrenia are due to such drug treatments. Surprisingly, there appear to be no studies to determine the effect of a combined antipsychotic-benzodiazepine treatment on GABA(A) receptors. We therefore measured both the GABA binding site ([3H]muscimol) and the benzodiazepine binding site ([3H]flumazenil) in the CNS of rats treated with either haloperidol, diazepam or a combination of the two drugs. The main findings of our study are that treatment with diazepam or the combination of diazepam and haloperidol results in regionally selective increases GABA binding sites but treatment with haloperidol alone decreases the GABA binding site in the thalamus but increases these sites in the hypothalamus. By contrast, treatment with diazepam, haloperidol and a combination of the two drugs resulted in widespread decreases in the number of benzodiazepine binding sites in the rat CNS. The notable exception to this outcome was increased numbers of benzodiazepine binding sites in the frontal cortex of rats that had received diazepam. Our data suggests that there are complex changes in the GABA(A) receptor following treatment with haloperidol, diazepam or a combination of these drugs. This outcome may be relevant to the therapeutic benefits of using both drugs in conjunction early in the treatment of a psychotic episode.

Lorazepam and MK-801 effects on behavioral and electrographic indices of alcohol withdrawal sensitization

Repeated cycles of chronic ethanol exposure and withdrawal result in sensitization of withdrawal-related CNS hyperexcitability that generally reflects an imbalance in activity of GABA and glutamate systems. Many pharmacological treatments for ethanol withdrawal target neuroadaptive changes in GABA and glutamate neurotransmission. The present study utilized a mouse model of repeated withdrawals to evaluate the ability of lorazepam and MK-801 treatments to antagonize behavioral and electroencephalographic (EEG) measures of sensitized withdrawal seizure activity. Adult male C3H/He mice received chronic intermittent ethanol vapor exposure in inhalation chambers (16 h/day) and during each withdrawal cycle, separate groups of mice were evaluated for handling-induced convulsions (HIC) or abnormal EEG (high-voltage "brief spindle episodes" (BSE)) activity. Lorazepam (0.5-1.0 mg/kg) or MK-801 (0.1-0.3 mg/kg) treatment at 1 h into each of three withdrawal cycles reduced behavioral (HIC) and electrographic (BSE) signs of seizure activity in a dose-related fashion compared to vehicle-treated mice. During a subsequent untreated withdrawal, mice previously treated with lorazepam or MK-801 for earlier withdrawals exhibited reduced HIC activity during the acute phase but exacerbated HIC activity during the protracted phase of this final (fourth) withdrawal cycle. Both lorazepam and MK-801 treatment conditions resulted in enhanced BSE activity during the entire fourth (untreated) withdrawal episode. Collectively, these results suggest that while treatment of repeated ethanol withdrawals with a benzodiazepine (lorazepam) or an NMDA receptor antagonist (MK-801) may have some initial benefits in ameliorating the development of sensitized withdrawal excitability, such treatment may also render subjects more vulnerable to seizure activity at later time points.

Anxiety in the First Attack of Vertigo

BACKGROUND: Although psychiatric disturbances have been reported in chronic vestibular disorders, little is known about the psychological impact of an acute vertigo attack.

METHODS: We conducted a comparative questionnaire study in 30 patients with a first attack of vestibular dysfunction and in 35 patients with a nonvesicular neurologic deficit of acute onset.

RESULTS: Patients with vertigo reported more anxiety than patients with nonvestibular neurologic deficits ( P = 0.002), despite the fact that premorbid anxiety was similar in both groups ( P = 0.5). No difference in anxiety levels was found between vertigo patients who vomited and those who were free of vegetative symptoms ( P = 0.97). Vertigo patients felt more disabled than nonvertigo patients ( P = 0.06), irrespective of the objective restrictions caused by the disease. The rate of depression did not differ between the groups of patients ( P = 0.09).

CONCLUSION: Patients with acute vertigo experience extreme anxiety, and this contributes to their feeling of disproportionate disability. The reason for emotional disturbances in vestibular dysfunction is probably the result of physiological connections between the vestibular and limbic system and deserves further neuroanatomic investigation.

The prevalence and clinical course of sedative-hypnotic abuse and dependence in a large cohort

Relatively little is known about the prevalence and clinical characteristics of dependence on sedative-hypnotics, and almost nothing has been published regarding abuse. This report relates information on Diagnostic and Statistical Manual of the American Psychiatric Association (DSM-IIIR) sedative-hypnotic use disorders among subjects from the Collaborative Study on the Genetics of Alcoholism (COGA). A standardized interview was used to generate data on 407 men and women in Group 1 with sedative-hypnotic dependence (4.4% of the COGA sample), 34 in Group 2 with abuse (0.4%), and 3,426 comparison subjects in Group 3 with alcohol dependence in the absence of a sedative-hypnotic use disorder (36.7%). The remaining COGA subjects (48.5%) were not included as they had neither alcohol nor sedative-hypnotic dependence or abuse. Those with sedative-hypnotic abuse or dependence were more likely to be Caucasian individuals with abuse or dependence on marijuana, cocaine, amphetamines, or opioids. Subjects in Groups 1 and 2 were also more likely to have histories of independent major depressive and panic disorders, as well as substance-induced mood disorders. Those with dependence, compared to abuse, were likely to be women, reported staying intoxicated for a day or more, but noted less abuse of opioids or amphetamines, although Group 2 members also had high rates of difficulties with sedative-hypnotics. These results highlight notable rates of sedative-hypnotic dependence in the COGA families, and indicate that while sedative-hypnotic abuse does occur, and while the clinical course can involve relatively serious problems, it is less common than dependence.

Chronic hypnotic use: deadly risks, doubtful benefit. REVIEW ARTICLE

In the United States, roughly 2/3 of all hypnotic prescriptions go to chronic users, who have taken hypnotics for an average of 5 years or more. Two large prospective epidemiological studies have shown that reported hypnotic use, especially use 30 times per month, is associated with an excess hazard of death. Indeed, use of hypnotics 30 times per month is associated with a similar mortality hazard to smoking 1-2 packs of cigarettes per day. Moreover, the hypnotic user's wish to improve daytime function is usually unfulfilled. The preponderance of evidence is that hypnotics impair performance, cognition and memory, increase the risk of automobile accidents and falls and promote unfavourable changes in personality. Due to tolerance, the sleep-promoting effects of hypnotics appear to be lost with chronic use. With long-term use, there is little controlled evidence that hypnotics produce benefits of any sort. More study of long-term hypnotic effects by public agencies is needed, but available evidence weighs strongly against long-term prescribing.

Lack of sex differences in anxiety behaviors during precipitated benzodiazepine withdrawal in rats

Nonprecipitated benzodiazepine (BZ) withdrawal has been reported to increase anxiety levels in rats. The present experiment determined if gender or hormonal status would modulate putative changes in anxiety-related behaviors during precipitated BZ withdrawal in rats. Intact and gonadectomized male and female rats were treated for 4 weeks with empty or diazepam (DZ)-filled silastic capsules. Animals were injected with the BZ antagonist flumazenil (RO15-1788; 5 mg/kg, i.p.) or vehicle, and immediately placed on the elevated plus-maze. Following the 10-min behavioral test, rats were decapitated and trunk blood was collected to measure corticosterone and gonadal hormone levels. During precipitated BZ withdrawal rats showed significantly decreased percent open-arm time; however, this finding was confounded by a significant decrease in activity levels (e.g., closed-arm entries and total-arm entries). Precipitated BZ withdrawal did not significantly attenuate percent open-arm entries, which factors out drug-induced changes in activity levels, compared to vehicle control animals. Overall, the results of this experiment suggest that precipitated BZ withdrawal does not significantly increase anxiety levels when compared to control animals.

Small platform stress attenuates the anxiogenic effect of diazepam withdrawal in the plus-maze test

The effect of stress on the behavioural changes caused by diazepam withdrawal was studied in mice. Diazepam (2.5 mg/kg) or vehicle was injected intraperitoneally twice a day for 2 weeks. When the last vehicle or diazepam injection had been administered to the mice, 12 h later, the mice were subjected to small platform stress exposure or left in their home cages. Small platform stress was induced by placing mice on small platforms (3.5 cm diameter) surrounded by water for 24 h. This experimental model contains several factors of stress like rapid eye movement (REM) sleep deprivation, isolation, immobilization and falling into the water. The plus-maze test was carried out with stressed mice as well as with mice not subjected to stress. Small platform stress induced an anxiolytic effect and diazepam withdrawal--an anxiogenic effect in the plus-maze test. Small platform stress also attenuated the anxiogenic effect of diazepam withdrawal. On the basis of this data it was proposed that small platform stress counteracts the anxiogenic effect of diazepam withdrawal in the plus-maze test. It was also proposed that the effect of stress on the signs of benzodiazepine withdrawal depends on the characteristics and duration of stress.

Modulation of synaptic GABAA receptor function by benzodiazepines in area CA3 of rat hippocampal slice cultures

The effects of the benzodiazepine agonist midazolam on GABAA receptor-mediated inhibition were investigated in area CA3 of hippocampal slice cultures. Midazolam (100 nM) increased the decay time constant (tau OFF) of miniature inhibitory postsynaptic currents (mIPSCs) recorded from pyramidal cells by approximately 40%, but did not significantly affect their activation rate or amplitude, consistent with saturation of postsynaptic GABAA receptors by a quantum of GABA. Non-stationary variance analysis of mIPSCs revealed that the unitary conductance of synaptic GABAA channels (approximately 31 pS) was unaffected by midazolam. Midazolam increased not only the tau OFF (51%), but also the amplitude (23%) of unitary IPSPs, recorded from pairs of monosynaptically connected inhibitory and pyramidal cells. Simulation of unitary IPSPs indicated that the increased amplitude was primarily due to the slow time constant of pyramidal cells. Finally, the mean amplitude, tau OFF, and single-channel conductance of mIPSCs recorded in cultures chronically exposed to midazolam (0.1-10 microM) for 2 weeks were not different from control mIPSCs, nor was their response to midazolam. We conclude that benzodiazepines increase synaptic GABAA channel open time, as described previously, and that this results in an increase in both the amplitude and duration of IPSPs in pyramidal cells.