The role of the opioid system in alcohol dependence

Safety and tolerability of as-needed nalmefene in the treatment of alcohol dependence: results from the Phase III clinical programme

OBJECTIVE

To investigate safety and tolerability of nalmefene for reduction of alcohol consumption in alcohol-dependent patients.

METHODS

Pooled data from three randomized, placebo-controlled studies (two 6-month; one 12-month) of 18 mg nalmefene (as-needed use) in alcohol-dependent patients looking at the total population (placebo n = 824, nalmefene n = 1123) and patients with high/very high drinking risk levels at screening and randomization (target population: placebo n = 374, nalmefene n = 450).

RESULTS

In the study, 62.7% of patients on placebo and 74.7% on nalmefene in the total population had treatment-emergent adverse events (TEAEs). Fourty-seven (5.9%) on placebo and 149 (13.0%) on nalmefene dropped out due to TEAEs. Thirty-five (4.4%) on placebo and 57 (5.0%) on nalmefene had serious adverse events. Tolerability and safety were similar in the target population and total population. Most frequent TEAEs were transient, mainly occurring at treatment initiation. There was no difference in tolerability and safety if nalmefene was taken daily or intermittently; no signal of increased risk of suicide-related behavior with nalmefene. The higher incidence of psychiatric events in the nalmefene group was mainly due to the TEAE of confusional state.

CONCLUSIONS

Although there was a higher incidence of TEAEs and TEAEs leading to dropout, nalmefene was well-tolerated and no major safety issues were identified.

Methoxyflavones from Stachys glutinosa with binding affinity to opioid receptors: in silico, in vitro, and in vivo studies

Fractionation of the bioactive dichloromethane extract from the aerial parts of Stachys glutinosa led to the isolation of four flavones, xanthomicrol (1), sideritoflavone (2), 8-methoxycirsilineol (3), and eupatilin (4), along with two neo-clerodane diterpenes, roseostachenone (8) and a new compound, 3α,4α-epoxyroseostachenol (7). In order to study structure-activity relationships, two methoxyflavones [5-demethyltangeretin (5) and tangeretin (6)] were synthesized by the methoxylation of xanthomicrol. The isolated compounds (1-4, 7, and 8) as well as the xanthomicrol semisynthetic derivatives (5 and 6) were evaluated for their binding affinity to the μ and δ opioid receptors. Xanthomicrol was the most potent binder to both μ and δ receptors, with a Ki value of 0.83 and 3.6 μM, respectively. Xanthomicrol administered intraperitoneally in mice at a dose of 80 mg/kg significantly reduced morphine-induced antinociception in the tail flick test. Our results suggested that xanthomicrol is a μ opioid receptor antagonist. Docking experiments were carried out to acquire a deeper understanding about important structural aspects of binding of xanthomicrol. In summary, these data suggest that xanthomicrol is a valuable structure for further development into a potential μ opioid receptor antagonist.

Clinical relevance of as-needed treatment with nalmefene in alcohol-dependent patients

Nalmefene is the first drug approved for reduction of alcohol consumption. The aim of this study was to evaluate the clinical relevance of treatment with nalmefene in alcohol-dependent patients with a high drinking risk level from two randomised placebo-controlled 6-month studies (NCT00811720 and NCT00812461). Response criteria were based on alcohol consumption, Clinical Global Impression, and Short Form Health Survey mental component summary scores at month 6, analysed using logistic regression. The proportion of responders was higher in the nalmefene group than in the placebo group with odds ratios significantly in favour of nalmefene for all responder criteria; numbers-needed-to-treat ranged from 6 to 10. Significant differences from placebo in clinician-rated and patient-reported outcomes, and liver enzymes further supported the clinical relevance of the treatment effect. In conclusion, this study supports the clinical relevance of nalmefene treatment in patients with alcohol dependence. Nalmefene may help to reduce the alcohol-related burden and the large treatment gap, with currently less than 10% of alcohol-dependent patients in Europe receiving treatment.

Pharmacology of cognitive enhancers for exposure-based therapy of fear, anxiety and trauma-related disorders

Pathological fear and anxiety are highly debilitating and, despite considerable advances in psychotherapy and pharmacotherapy they remain insufficiently treated in many patients with PTSD, phobias, panic and other anxiety disorders. Increasing preclinical and clinical evidence indicates that pharmacological treatments including cognitive enhancers, when given as adjuncts to psychotherapeutic approaches [cognitive behavioral therapy including extinction-based exposure therapy] enhance treatment efficacy, while using anxiolytics such as benzodiazepines as adjuncts can undermine long-term treatment success. The purpose of this review is to outline the literature showing how pharmacological interventions targeting neurotransmitter systems including serotonin, dopamine, noradrenaline, histamine, glutamate, GABA, cannabinoids, neuropeptides (oxytocin, neuropeptides Y and S, opioids) and other targets (neurotrophins BDNF and FGF2, glucocorticoids, L-type-calcium channels, epigenetic modifications) as well as their downstream signaling pathways, can augment fear extinction and strengthen extinction memory persistently in preclinical models. Particularly promising approaches are discussed in regard to their effects on specific aspects of fear extinction namely, acquisition, consolidation and retrieval, including long-term protection from return of fear (relapse) phenomena like spontaneous recovery, reinstatement and renewal of fear. We also highlight the promising translational value of the preclinial research and the clinical potential of targeting certain neurochemical systems with, for example d-cycloserine, yohimbine, cortisol, and L-DOPA. The current body of research reveals important new insights into the neurobiology and neurochemistry of fear extinction and holds significant promise for pharmacologically-augmented psychotherapy as an improved approach to treat trauma and anxiety-related disorders in a more efficient and persistent way promoting enhanced symptom remission and recovery.

[Place of the opioid system in biology and treatment of Alcohol Use Disorder]

While the DSM 5 has formalized the terminology "Alcohol Use Disorders" (AUD) or "disorders of the use of alcohol" (UAW French translation in progress), the term "alcohol dependence" still used in ICD-10, apriority in the future ICD-11 and above in clinical practice. Addiction to alcohol is the cause of mortality and major morbidity. In terms of therapeutic strategies for its management, alongside the maintenance of abstinence after withdrawal (with a high rate of relapse), the reduction of alcohol consumption below certain thresholds of intake is emerging in order to reduce risk, improve health and regain control of consumption even be an intermediate step towards abstinence. The role of the endogenous opioid system in the modulation of the activity of dopaminergic neurons from the circuit of reward and motivation is well established. An unsteadiness of this system has been described in the alcohol dependence. Indeed, a hypofunction of the endorphin pathway and its mu receptor and a hyperactivity of the dynorphin pathway and its kappa receptor participate in the alcohol reinforcing effects (especially positive and negative). The development of active molecules in this system allows better management of alcohol dependence. Besides naltrexone (mu antagonist) allowed in the maintenance of abstinence after withdrawal, another molecule (nalmefene) with modulating properties of μ and κ opioid receptors is the first drug having obtained an MA in reducing consumption in adult patients with alcohol dependence. Its modulating original pharmacological properties by targeting both the positive but also the negative reinforcing effects of alcohol, are responsible for its development in reducing consumption in the alcohol dependence.