Mirtazapine, and mirtazapine-like compounds as possible pharmacotherapy for substance abuse disorders: evidence from the bench and the bedside

Pharmacologic profile of ITI-333: a novel molecule for treatment of substance use disorders

RATIONALE

Medications are urgently needed to treat symptoms of drug withdrawal and mitigate dysphoria and psychiatric comorbidities that drive opioid abuse and relapse. ITI-333 is a novel molecule in development for treatment of substance use disorders, psychiatric comorbidities, and pain.

OBJECTIVE

Characterize the preclinical profile of ITI-333 using pharmacological, behavioral, and physiological assays.

METHODS

Cell-based assays were used to measure receptor binding and intrinsic efficacy of ITI-333; animal models were employed to assess effects on opioid reinstatement, precipitated oxycodone withdrawal, and drug abuse liability.

RESULTS

In vitro, ITI-333 is a potent 5-HT2A receptor antagonist (Ki = 8 nM) and a biased, partial agonist at μ-opioid (MOP) receptors (Ki = 11 nM; lacking β-arrestin agonism) with lesser antagonist activity at adrenergic α1A (Ki = 28 nM) and dopamine D1 (Ki = 50 nM) receptors. In vivo, ITI-333 blocks 5-HT2A receptor-mediated head twitch and MOP receptor-mediated effects on motor hyperactivity in mice. ITI-333 alone is a naloxone-sensitive analgesic (mice) which suppresses somatic signs of naloxone-precipitated oxycodone withdrawal (mice) and heroin cue-induced reinstatement responding without apparent tolerance or physical dependence after chronic dosing (rats). ITI-333 did not acutely impair gastrointestinal or pulmonary function (rats) and was not intravenously self-administered by heroin-maintained rats or rhesus monkeys.

CONCLUSIONS

ITI-333 acts as a potent 5-HT2A receptor antagonist, as well a biased MOP receptor partial agonist with low intrinsic efficacy. ITI-333 mitigates opioid withdrawal/reinstatement, supporting its potential utility as a treatment for OUD.

IUPHAR review - Data-driven computational drug repurposing approaches for opioid use disorder

Opioid Use Disorder (OUD) is a chronic and relapsing condition characterized by the misuse of opioid drugs, causing significant morbidity and mortality in the United States. Existing medications for OUD are limited, and there is an immediate need to discover treatments with enhanced safety and efficacy. Drug repurposing aims to find new indications for existing medications, offering a time-saving and cost-efficient alternative strategy to traditional drug discovery. Computational approaches have been developed to further facilitate the drug repurposing process. In this paper, we reviewed state-of-the-art data-driven computational drug repurposing approaches for OUD and discussed their advantages and potential challenges. We also highlighted promising repurposed candidate drugs for OUD that were identified by computational drug repurposing techniques and reviewed studies supporting their potential mechanisms of action in treating OUD.

Simultaneous separation and determination of several chiral antidepressants and their enantiomers in wastewater by online heart-cutting two-dimensional liquid chromatography

A novel method for simultaneous separation and detection of the racemates and the enantiomers of common chiral antidepressants in wastewater matrix was developed by online heart-cutting two-dimensional liquid chromatography (2D-LC) coupled to solid-phase extraction (SPE). Screening of chiral stationary phases (CSPs) and chromatographic conditions was investigated for complete enantioseparation to be compatible with RP-HPLC in 1st D-LC. Using methanol-0.1 % (v/v) ammonia solution as mobile phase, a 2D-LC system was configured by reversed mode with a combination of C18 column and the serially CPS columns as 2D-LC stationary phases respectively. The target analytes could achieve satisfactory transformation between 2D-LCs with transfer rate of 90.57-98.58 %. By means of freeze-drying and SPE, three antidepressants in wastewater were greatly preconcentrated under the optimized conditions, improving the method performance. The racemates and the enantiomers of mirtazapine, bupropion and fluoxetine exhibited good linearity in the range of 0.10-30.00 ng/mL (R2≥0.9986), and LODs and LOQs ranged in 0.0183-0.0549 ng/mL and 0.0661-0.1831 ng/mL, respectively. By this way, the method was successfully applied to simultaneous determination of the racemates and the enantiomers of mirtazapine, bupropion and fluoxetine in wastewater samples. Among them, three samples contained bupropion at level of 0.401-0.822 ng/mL, and mirtazapine at level of 0.328 and fluoxetine at level of 0.381 ng/mL were detected respectively in the other two samples. The enantiomers were at level of 0.140-0.189 ng/mL for mirtazapine, 0.182-0.419 ng/mL for bupropion and 0.179-0.204 ng/mL for fluoxetine, respectively. The proposed method providing an efficient approach to monitoring chiral drugs and their enantiomers in wastewater, facilitating to pollution assessment of chiral drugs in the environment and regional survey of illicit abuse in drug control.

Mirtazapine: A One-Stop Strategy for Treatment of Opioid Withdrawal Symptoms

Public health efforts to reduce the opioid overdose epidemic and treat opioid use disorder (OUD) have met with challenges associated with current non-standardized approaches to managing opioid withdrawal symptoms, such as itching, jitteriness, anxiety, depression, craving, vomiting, diarrhea, insomnia, and anorexia. These symptoms pose substantial obstacles to the safe initiation of medications for OUD, maintenance of long-term sobriety, and prevention of relapse. In clinical practice, multiple medications (polypharmacy) are prescribed to manage these withdrawal symptoms, including ondansetron and promethazine for vomiting and nausea, loperamide and Lomotil for diarrhea, hydroxyzine and doxepin for pruritus, benzodiazepines, the Z-drugs, and melatonin for insomnia, and benzos, tricyclic antidepressants (TCAs), and various serotonergic agents for anxiety. This polypharmacy is associated with an increased risk of adverse drug-drug interactions and adverse drug events, increased medical costs, and increased odds of medication non-adherence and relapse. We propose an alternative single medication, mirtazapine, a noradrenergic and specific serotonergic receptor antagonist, that can be used for myriad symptoms of opioid withdrawal. Case series, clinical studies, and clinical trials have shown mirtazapine to be effective for treating nausea and vomiting resulting from multiple etiologies, including hyperemesis gravidarum and chemotherapy-induced emesis. Other evidence supports the salutary effects of mirtazapine on itching and craving. Research findings support mirtazapine's beneficial effects on diarrhea and anxiety, a consequence of its modulating effects on serotonergic receptors mediating mood and gastrointestinal symptoms. There is also evidence supporting its efficacy as a potent and non-addictive sleep aid, which presents itself as a solution for insomnia associated with opioid withdrawal. The current review presents evidence from extant literature supporting mirtazapine as a one-drug strategy to treat the variety of symptoms of opioid withdrawal. This one-drug strategy has much potential to decrease polypharmacy, adverse drug events, relapse, and healthcare cost and increase the likelihood of prolonged sobriety and better quality of life for people living with OUD.

Investigating the potential of mirtazapine to induce drug-seeking behavior in free-choice drinking mouse model

Addiction to various drugs and chemicals is a significant public health concern worldwide. Addiction to prescription medications has increased due to the psychoactive effects of these medications, their availability, low price, and the lack of legal consequences for abusers. One of such prescription medication is mirtazapine (MIRT). MIRT is an antidepressant that has recently been reported to be abused and could induce withdrawal symptoms in different case studies. No previous study has investigated its abuse potential in animal models of drug addiction. Here, we conducted a free-choice drinking paradigm to investigate voluntary drinking of MIRT at two different concentrations. Male BALB/c mice were given unlimited access to two water bottles for five days before being divided into three groups: the first group had free access to two water bottles. The second group (MIRT10) and the third group (MIRT20) was allowed unlimited choice to one bottle of water and one bottle of MIRT at concentrations of 0.03 and 0.06 mg/mL, respectively. The average daily MIRT intake in the MIRT20 group was significantly higher on all tested days than that in the MIRT10 group. Moreover, mice in the MIRT20 group preferred to self-administer MIRT over water, indicating that MIRT can induce drug-seeking behavior. To further investigate the addictive potential of MIRT and its possible deterioration of memory and recognition, as reported with several known drugs of abuse, animals underwent a novel object recognition test. Mice in the MIRT20 group demonstrated significant deterioration in memory and recognition, indicating its effects on different brain regions involved in recognition, similar to other known drugs of abuse. The forced swimming test and tail suspension test were used to test MIRT-induced withdrawal symptoms after forced abstinence. After eight days of abstinence, mice in the MIRT20 group demonstrated significant depression-like symptoms in both the TST and FST, manifested by a significant increase in immobility time. MIRT was shown to induce drug-seeking behavior, deteriorate recognition, and cause withdrawal symptoms. This might confirm that MIRT has the potential to induce drug dependence and further studies are warranted to explore the neurobiological basis of MIRT-induced drug-seeking behavior.

A serotonergic biobehavioral signature differentiates cocaine use disorder participants administered mirtazapine

Cocaine use disorder (CUD) patients display heterogenous symptoms and unforeseeable responses to available treatment approaches, highlighting the need to identify objective, accessible biobehavioral signatures to predict clinical trial success in this population. In the present experiments, we employed a task-based behavioral and pharmacogenetic-fMRI approach to address this gap. Craving, an intense desire to take cocaine, can be evoked by exposure to cocaine-associated stimuli which can trigger relapse during attempted recovery. Attentional bias towards cocaine-associated words is linked to enhanced effective connectivity (EC) from the anterior cingulate cortex (ACC) to hippocampus in CUD participants, an observation which was replicated in a new cohort of participants in the present studies. Serotonin regulates attentional bias to cocaine and the serotonergic antagonist mirtazapine decreased activated EC associated with attentional bias, with greater effectiveness in those CUD participants carrying the wild-type 5-HT2CR gene relative to a 5-HT2CR single nucleotide polymorphism (rs6318). These data suggest that the wild-type 5-HT2CR is necessary for the efficacy of mirtazapine to decrease activated EC in CUD participants and that mirtazapine may serve as an abstinence enhancer to mitigate brain substrates of craving in response to cocaine-associated stimuli in participants with this pharmacogenetic descriptor. These results are distinctive in outlining a richer "fingerprint" of the complex neurocircuitry, behavior and pharmacogenetics profile of CUD participants which may provide insight into success of future medications development projects.

Mirtazapine Was Effective for a Patient With Benzodiazepine Dependence

OBJECTIVE

Benzodiazepine (BZD) dependence has become a social problem and results in poor outcomes. Only a few evidence-based treatments for pharmacotherapy, including antidepressants, are recommended.

METHODS

We reported about a 71-year-old man with onset of blindness at 50 years of age due to pigmentary degeneration of the retina developed insomnia at age 59 years, characterized by nocturnal and early morning awakenings.

RESULTS

Mirtazapine was effective to not only treat sleep disturbance but also a craving for BZD.

CONCLUSIONS

The increases of dopamine, norepinephrine, and serotonin signaling by mirtazapine may be related to the effectiveness in reducing BZD dependence.

Mirtazapine-induced decrease in cocaine sensitization is enhanced by environmental enrichment in rats

Several studies have reported that mirtazapine attenuated the induction and expression of cocaine-induced locomotor sensitization. Animals placed in enriched housing environments have shown a decrease in cocaine-induced locomotor activity and sensitization. In addition, it has been suggested that a pharmacological treatment combined with a behavioral intervention increases the efficacy of the former. Thus, the objective of this study was to determine if dosing of mirtazapine in an enriched housing environment enhanced the mirtazapine-induced decrease on the induction and expression of cocaine-induced locomotor sensitization. Wistar male rats were dosed with cocaine (10 mg/kg, i.p.). During the drug-withdrawal phase, mirtazapine (30 mg/kg, i.p.) was administered under standard and enriched housing environmental conditions. The environmental enrichment consisted of housing the animals in enclosures with plastic toys, tunnels, and running wheels. After each administration, locomotor activity for each animal was recorded for 30 min. The study found that treatment with mirtazapine in an enriched housing environment produced an enhanced and persistent attenuation of the induction and expression of cocaine-induced locomotor sensitization. Additionally, it reduced the duration of cocaine-induced locomotor activity in the expression phase of locomotor sensitization. Dosing of mirtazapine in an enriched housing environment enhanced the effectiveness of mirtazapine to decrease cocaine-induced locomotor sensitization. This suggests the potential use of enriched environments to enhance the effect of mirtazapine.

Noradrenergic contributions to cue-driven risk-taking and impulsivity

RATIONALE

The flashing lights and sounds of modern casinos are alluring and may contribute to the addictive nature of gambling. Such cues can have a profound impact on the noradrenaline (NA) system, which could therefore be a viable therapeutic target for gambling disorder (GD). While there is substantial evidence to support the involvement of NA in the impulsive symptoms of GD, its function in mediating the "pro-addictive" impact of cues is less understood.

OBJECTIVE

We wished to investigate the role of NA in our rodent assay of decision making and impulsivity, the cued rat gambling task (crGT). Given that sex differences are prominent in addiction disorders, and increasingly reported in the monoaminergic regulation of behaviour, we also prioritised evaluating noradrenergic drugs in both sexes.

METHODS

Female and male rats were trained to stability on the crGT and then given intraperitoneal injections of the noradrenaline reuptake inhibitor atomoxetine, the α_2A receptor agonist guanfacine, the beta receptor antagonist propranolol, and the α₂ receptor antagonist yohimbine.

RESULTS

Atomoxetine dose-dependently improved decision-making score. Guanfacine selectively enhanced decision making in risk-preferring males and optimal performing females. Propranolol and yohimbine did not influence decision making. Atomoxetine and guanfacine reduced premature responses, while yohimbine bi-phasically affected this index of motor impulsivity.

CONCLUSIONS

These results support the hypothesis that NA is an important neuromodulator of the cue-induced deficits in decision making observed in laboratory-based gambling paradigms, and suggest that NAergic drugs like atomoxetine and guanfacine may be useful in treating GD.

Mirtazapine use may increase the risk of hypothyroxinaemia in patients affected by major depressive disorder

AIMS

Hypothyroxinaemia could be easily neglected if attention is paid only to patients with elevated thyroid-stimulating hormone. We aimed to assess the association between mirtazapine use and hypothyroxinaemia in patients affected by major depressive disorder.

METHODS

We conducted a retrospective cohort study in the Second Affiliated Hospital of Xinxiang Medical University between January 2016 and December 2018. Patients affected by major depression disorder and admitted to the hospital for treatment during the study period and who had thyroid tests at admission and after treatment were included. Mirtazapine use during hospitalization was the exposure measure and newly developed hypothyroxinaemia was as the primary outcome and structure parameters of thyroid homeostasis were the secondary outcomes of this study. Log-binomial model was used to estimate the association between mirtazapine use and hypothyroxinaemia, after adjusting for potential confounding factors.

RESULTS

A total of 220 eligible patients were included in the final analysis. The incidence of hypothyroxinaemia in patients who used mirtazapine was higher (37.5%) than those patients who did not use (19.7%). The relative risk of developing hypothyroxinaemia was 1.70 (95% confidence interval: 1.21-2.43) for mirtazapine use, after adjusting for confounding factors. The degree of reduction in thyroid feedback quantile-based index in mirtazapine group was significantly greater than that in nonmirtazapine group.

CONCLUSION

Mirtazapine use was associated with the increased risk of developing hypothyroxinaemia. The underlying mechanism may be involved the changed central set point of thyroid homeostasis, in which pituitary was in a possibly impaired sensitivity to the lower level of thyroid hormones.

Mirtazapine decreased induction and expression of cocaine + nicotine-induced locomotor sensitisation in rats

Objectives: Concurrent abuse of cocaine and nicotine is considered a public health problem. To date, no effective therapy has been known to reduce the reinforcing effects of concurrent use of cocaine and nicotine. Mirtazapine, an antagonist of the α₂-adrenoceptor and the 5-HT_2A/C and the 5-HT₃ receptors has proven effective in reducing the cocaine, nicotine and methamphetamine behavioural effects in humans and animals. Our study evaluated the effect of mirtazapine on enhancing locomotor activity during the induction and expression of locomotor sensitisation induced by a cocaine + nicotine mixture.Methods: Wistar rats were dosed with cocaine, nicotine or cocaine + nicotine combination. Mirtazapine (30 mg/kg, i.p.) was administered during the extinction phase.Results: Mirtazapine decreased cocaine + nicotine-induced locomotor activity and induction and expression of locomotor sensitisation. In addition, we found that co-administration of mecamylamine and mirtazapine significantly enhanced the effect of mirtazapine on cocaine + nicotine-induced locomotor activity during induction and expression of behavioural sensitisation.Conclusions: Our results suggest that mirtazapine demonstrated efficacy in decreasing the psycho-stimulant effects of concurrent use of cocaine and nicotine.

Mirtazapine reduces the expression of cocaine-induced locomotor sensitization in male and female Wistar rats

BACKGROUND

Epidemiological studies have described that women are more vulnerable to the reinforcing effects of cocaine. In animals, the findings are similar: female rats show higher levels of cocaine self-administration and increased cocaine-induced locomotor activity. In contrast, women with depression respond better to treatment with antidepressants, however their therapeutic response to tetracyclic antidepressants is lower. Several studies have shown that mirtazapine-a tetracyclic antidepressant-decreases the behavioral effects of cocaine in male rats. The objective of this study was to evaluate the efficacy of daily dosing of mirtazapine on cocaine-induced locomotor activity and sensitization in naive female rats compared to male rats.

METHODS

Male and female Wistar rats were daily dosed with 10 mg/kg of cocaine. During extinction, cocaine was withdrawn and the groups received daily mirtazapine (30 mg/kg, i.p.) or saline. Tamoxifen was administered during the antagonism phase. After each administration, locomotor activity for each animal was recorded for 30 min in transparent Plexiglass activity chambers.

RESULTS

In this study, a higher cocaine locomotor response was found in females than in males and the mirtazapine was equally effective in decreasing cocaine-induced locomotor activity and the expression of locomotor sensitization in male and female rats. In addition, co-administration of mirtazapine and tamoxifen enhanced the efficacy of mirtazapine in female rats.

CONCLUSION

The results suggest that mirtazapine may be considered an effective therapeutic option for the treatment of cocaine use disorder in men and women.

The Antidepressant Mirtazapine Inhibits Hepatic Innate Immune Networks to Attenuate Immune-Mediated Liver Injury in Mice

Activation of the innate immune system, including tissue macrophages and associated neutrophil infiltration, is an important driver of subsequent adaptive immune responses in many autoimmune diseases, including autoimmune hepatitis (AIH). The antidepressant mirtazapine has a unique complex pharmacology, altering signaling through a number of serotonin and histamine receptors that can impact macrophage function; an effect potentially influencing AIH outcome. In the mouse model of concanavalin A (Con A) induced liver injury (mimics many aspects of human AIH), in which early innate immune activation (i.e., stimulated hepatic macrophages/monocytes recruit neutrophils and additional monocytes to the liver) critically drives immune-mediated hepatitis induction, mirtazapine strikingly and dose-dependently inhibited Con A-induced liver injury. This inflammation-suppressing effect of mirtazapine was linked to an attenuation of Con A-stimulated early innate immune responses within the liver, including inhibition of hepatic macrophage/monocyte activation, decreased hepatic macrophage/monocyte-derived pro-inflammatory cytokine (e.g., TNFα) and chemokine (e.g., CXCL1 and CXCL2) production, suppression of Con A-induced increases in the hepatic expression of the neutrophil relevant endothelial cell adhesion molecule ICAM-1, with the resultant significant reduction in neutrophil recruitment into the liver. Consistent with our findings in the Con A model, mirtazapine also significantly reduced activation-induced release of cytokine/chemokine mediators from human CD14⁺ monocytes in vitro. Conclusion: Our data suggest that mirtazapine can attenuate hepatic innate immune responses that critically regulate the subsequent development of autoimmune liver injury. Therefore, given that it is a safe and widely used medication, mirtazapine may represent a novel therapeutic approach to autoimmune liver disease.

Mirtazapine attenuates nicotine-seeking behavior in rats

BACKGROUND

Nicotine is the major psychoactive component of tobacco. A number of pharmacological therapies have been evaluated, with poor results. Given the lack of success of these therapies, several authors have proposed alternative therapeutic strategies. One of these is the use of antidepressant drugs that may have a specific effect on the neural pathways or receptors underlying nicotine addiction. Mirtazapine is an antagonist of α₂ NE receptors (noradrenergic receptor), 5-HT_2A/C and 5-HT₃ receptors and has demonstrated efficacy in reducing behavioral effects induced by drugs of abuse in human and animal models.

AIMS

In this study, we evaluated the effect of chronic dosing of mirtazapine during extinction on the re-acquisition of nicotine-seeking in rodents.

METHODS

We used the nicotine self-administration paradigm to assess the effects of mirtazapine on rats trained to self-administer nicotine under a pharmacological fixed-ratio schedule. Mirtazapine (30 mg/kg, i.p.) was administered during extinction.

RESULTS

In this work, we found that mirtazapine attenuates the re-acquisition of nicotine-seeking responses.

CONCLUSIONS

These results support the use of mirtazapine in clinical controlled trials as a useful therapy that prolongs and increases rates of preventing relapse into nicotine intake in humans.

Opioid tapering in patients with prescription opioid use disorder: A retrospective study

BACKGROUND AND AIMS

Opioid use disorder (OUD) refers to a maladaptive pattern of opioid use leading to clinically significant impairment or distress. OUD causes, and vice versa, misuses and abuse of opioid medications. Clinicians face daily challenges to treat patients with prescription opioid use disorder. An evidence-based management for people who are already addicted to opioids has been identified as the national priority in the US; however, options are limited in clinical practices. In this study, we aimed to explore the success rate and important adjuvant medications in the medication assisted treatment with temporary use of methadone for opioid discontinuation in patients with prescription OUD.

METHODS

This is a retrospective chart review performed at a private physician office for physical medicine and rehabilitation. We reviewed all medical records dated between December 1st, 2011 and August 30th, 2016. The initial evaluation of the included patients (N=140) was completed between December 1st, 2011 and December 31st, 2014. They all have concumittant prescription OUD and chronic non-cancer pain. The patients (87 female and 53 male) were 46.7±12.7 years old, and had a history of opioid use of 7.7±6.1 years. All patients received the comprehensive opioid taper treatments (including interventional pain management techniques, psychotherapy, acupuncture, physical modalities and exercises, and adjuvant medications) on top of the medication assisted treatment using methadone (transient use). Opioid tapering was considered successful when no opioid medication was used in the last patient visit.

RESULTS

The 140 patients had pain of 9.6±8.4 years with 8/10 intensity before treatment which decreased after treatment in all comparisons (p<0.001 for all). Opioids were successfully tapered off in 39 (27.9%) patients after 6.6±6.7 visits over 8.8±7.2 months; these patients maintained opioid abstinence over 14.3±13.0 months with regular office visits. Among the 101 patients with unsuccessful opioid tapering, 13 patients only visited the outpatient clinic once. Significant differences were found between patients with and without successful opioid tapering in treatment duration, number of clinic visits, the use of mirtazepine, bupropion, topiramate, and trigger point injections with the univariate analyses. The use of mirtazepine (OR, 3.75; 95% CI, 1.48-9.49), topiramate (OR, 5.61; 95% CI, 1.91-16.48), or bupropion (OR, 2.5; 95% CI, 1.08-5.81) was significantly associated with successful opioid tapering. The associations remain significant for mirtazepine and topiramate (not bupropion) in different adjusted models.

CONCLUSIONS

With comprehensive treatments, 27.9% of patients had successful opioid tapering with opioid abstinence for over a year. The use of mirtazepine, topiramate, or likely bupropion was associated with successful opioid tapering in the medication assisted treatment with temporary use of methadone. Opioid tapering may be a practical option and should be considered for managing prescription OUD.

IMPLICATIONS

For patients with OUD, indefinite opioid maintenance treatment may not be necessary. Considering the ethical values of autonomy, nonmaleficence, and beneficence, clinicians should provide patients with OUD the option of opioid tapering.

Mirtazapine attenuates cocaine seeking in rats

BACKGROUND

Relapse to cocaine use is a major problem in the clinical treatment of cocaine addiction. Antidepressants have been studied for their therapeutic potential to treat cocaine use disorder. Research has suggested that antidepressants attenuate both drug craving and the re-acquisition of drug-seeking and drug-taking behaviors. This study examined the efficacy of mirtazapine, an antidepressant/anxiolytic, in decreasing cocaine seeking in rats.

METHODS

We used the cocaine self-administration paradigm to assess the effects of mirtazapine on rats trained to self-administer cocaine or food under a fixed-ratio schedule. Mirtazapine (30 mg/kg, i.p.) was administered during extinction.

RESULTS

Mirtazapine significantly attenuated non-reinforced lever-press responses during extinction. Moreover, the mirtazapine dosed for 30 days during extinction produced sustained attenuation of lever-press responses during re-acquisition of cocaine self-administration, without changing food-seeking behavior. Our results showed that mirtazapine attenuated the re-acquisition of cocaine-seeking responses.

CONCLUSION

Our study pointed to the efficacy of mirtazapine in reducing the risk of drug relapse during abstinence, suggesting for its potential use as a novel pharmacological agent to treat drug abuse.

Dose- and time-dependent effects of mirtazapine on the expression of cocaine-induced behavioral sensitization in rats

Relapse to cocaine use is a major problem in the clinical treatment of cocaine dependence. Antidepressant medications have been studied as potential therapeutic drugs to relieve a cocaine dependence disorder. Mirtazapine is an antidepressant implicated in reducing behavioral alterations induced by drugs of abuse. We have reported elsewhere that 30mg/kg mirtazapine administered for 30 days during cocaine extinction significantly attenuated the induction and expression of cocaine-induced locomotor sensitization and decreased the duration of the cocaine-induced locomotor effect. This study focused on exploring whether different mirtazapine dosing regimens could optimize and/or improve the effect of 30mg/kg mirtazapine administered for 30 days on cocaine-induced locomotor activity during the expression phase of behavioral sensitization. Our study revealed that the daily dosing regimen with a fixed dose of mirtazapine (30mg/kg ip) over 60 days improved the decrease in cocaine-induced locomotor activity and behavioral sensitization obtained by dosing of 30mg mirtazapine for 30 days. In addition, it showed that a dosing regimen of 30mg/Kg mirtazapine for 30 days managed to reduce cocaine toxicity. These results suggested that dosage of mirtazapine for 30 consecutive days may be an effective therapy.

Mirtazapine and ketanserin alter preference for gambling-like schedules of reinforcement in rats

Drug and behavioral addictions have overlapping features, e.g., both manifest preference for larger, albeit costlier, reinforcement options in cost/benefit decision-making tasks. Our prior work revealed that the mixed-function serotonergic compound, mirtazapine, attenuates behaviors by rats motivated by abused drugs. To extend this work to behavioral addictions, here we determined if mirtazapine and/or ketanserin, another mixed-function serotonin-acting compound, can alter decision-making in rats that is independent of drug (or food)-motivated reward. Accordingly, we developed a novel variable-ratio task in rats wherein intracranial self-stimulation was used as the positive reinforcer. Using lever pressing for various levels of brain stimulation, the operant task provided choices between a small brain stimulation current delivered on a fixed-ratio schedule (i.e., a predictable reward) and a large brain stimulation delivered following an unpredictable number of responses (i.e., a variable-ratio schedule). This task allowed for demonstration of individualized preference and detection of shifts in motivational influences during a pharmacological treatment. Once baseline preference was established, we determined that pretreatment with mirtazapine or ketanserin significantly decreased preference for the large reinforcer presented after gambling-like schedules of reinforcement. When the rats were tested the next day without drug, preference for the unpredictable large reinforcer option was restored. These data demonstrate that mirtazapine and ketanserin can reduce preference for larger, costlier reinforcement options, and illustrate the potential for these drugs to alter behavior.

Bupropion Augmentation in a Case of Compulsive Buying Disorder

BACKGROUND

Compulsive buying disorder (CBD) is a condition characterized by excessive preoccupations, impulses, and behaviors regarding buying, resulting in serious psychological, social, and financial problems. Even though it has not been included in Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, "behavioral addictions" section, CBD is a hot topic in current clinical psychiatry, because of its relevant prevalence (at least 5% in adult populations) and severe effect on quality of life.The CBD shares some clinical features with substance-related and behavioral addictions, impulse control disorders, and obsessive compulsive disorder, and it is often comorbid with other psychiatric illnesses (especially depressive and anxiety disorders). The treatment of CBD is therefore difficult, and clear therapeutic guidelines are not yet available. Treating the comorbid disorders as the first-line approach, or combining drugs with different pharmacodynamic profiles, has been suggested to address this challenging condition.

CASE

A 60-year-old woman affected by a severe form of CBD with comorbid major depressive disorder, resistant/intolerant to previous selective serotonin reuptake inhibitor treatments and only partially responder to mirtazapine, achieved a good clinical improvement adding bupropion.

CONCLUSIONS

Combining 2 agents with different pharmacological profiles and mechanisms of action, such as bupropion and mirtazapine, could be a useful strategy in the management of complex CBD cases.

A Review of the Literature of Mirtazapine in Co-Occurring Depression and an Alcohol Use Disorder

BACKGROUND

Prior medication studies involving individuals with major depression in combination with an alcohol use disorder (MDD/AUD) have mainly focused on SSRI and tricyclic antidepressants, with generally ineffective results. Consequently, effective treatments for that common comorbid condition remain elusive. Mirtazapine is an antidepressant medicine with a unique pharmacological profile, whose effectiveness for treating non-comorbid depression reportedly may exceed that of SSRIs.

OBJECTIVE/METHODS

We now review the published literature regarding the tolerability and efficacy of mirtazapine for the treatment of the depression and the pathological alcohol ingestion of individuals with co-occurring MDD/AUD, including a review of four of our own small studies and two studies conducted outside the United States.

RESULTS/CONCLUSIONS

The findings of these studies suggest that mirtazapine is well tolerated among persons with comorbid MDD/AUD. Results also provide some evidence of efficacy for mirtazapine for decreasing the level of depression of persons with co-occurring MDD/AUD, and suggest that decreases in depression may occur relatively quickly after starting treatment, but provide no evidence of effectiveness for decreasing the level of alcohol ingestion. Large-scale double-blind, placebo-controlled studies are warranted to further clarify the tolerability and efficacy of mirtazapine among individuals with MDD/AUD.

Pharmacologically distinct pramipexole-mediated akinesia vs. risk-taking in a rat model of Parkinson's disease

Pramipexole and ropinirole are dopamine agonists that are efficacious in treating motor disturbances of neuropathologies, e.g., Parkinson's disease and restless legs syndrome. A significant portion of treated patients develop impulsive/compulsive behaviors. Current treatment is dose reduction or switching to an alternative dopamine replacement, both of which can undermine the motor benefits. Needed is a preclinical model that can assist in identifying adjunct treatments to dopamine agonist therapy that reduce impulsive/compulsive behaviors without interfering with motor benefits of the dopamine agonist. Toward that objective, the current study implemented a rat model of Parkinson's disease to behaviorally profile chronically administered pramipexole. This was accomplished with male Sprague-Dawley rats wherein (i) 6-hydroxydopamine-induced lesions of the dorsolateral striatum produced Parkinson's disease-like akinesia, measured in the forelimbs, (ii) intracranial self-stimulation-mediated probability discounting indicated impulsivity/risk-taking, and (iii) two doses of pramipexole were continuously administered for 14-28days via osmotic minipumps to mirror the chronic, stable exposure achieved with extended release formulations. The atypical antidepressant, mirtazapine, is known to reduce behaviors associated with drug addiction in rats; thus, we demonstrated model utility here by determining the effects of mirtazapine on pramipexole-induced motor improvements versus probability discounting. We observed that forelimb akinesia subsequent to striatal lesions was attenuated by both pramipexole doses tested (0.3 and 1.2mg/kg/day) within 4h of pump implant dispensing 0.3mg/kg/day and 1h by 1.2mg/kg/day. By contrast, 12-14days of infusion with 0.3mg/kg/day did not alter discounting, but increases were obtained with 1.2mg/kg/day pramipexole, with 67% of 1.2mg/kg/day-treated rats meeting categorical criteria for 'high risk-taking'. Insertion of a second minipump delivering mirtazapine did not alter motor function during 14days of co-administration with pramipexole, but was sufficient to attenuate risk-taking. These outcomes revealed distinct probability discounting and anti-akinesia profiles for pramipexole, indicating that pharmacotherapy, (e.g., mirtazapine treatments), can be developed that reduce risk-taking while leaving motor benefits intact.

Identification of Treatment Targets in a Genetic Mouse Model of Voluntary Methamphetamine Drinking

Methamphetamine has powerful stimulant and euphoric effects that are experienced as rewarding and encourage use. Methamphetamine addiction is associated with debilitating illnesses, destroyed relationships, child neglect, violence, and crime; but after many years of research, broadly effective medications have not been identified. Individual differences that may impact not only risk for developing a methamphetamine use disorder but also affect treatment response have not been fully considered. Human studies have identified candidate genes that may be relevant, but lack of control over drug history, the common use or coabuse of multiple addictive drugs, and restrictions on the types of data that can be collected in humans are barriers to progress. To overcome some of these issues, a genetic animal model comprised of lines of mice selectively bred for high and low voluntary methamphetamine intake was developed to identify risk and protective alleles for methamphetamine consumption, and identify therapeutic targets. The mu opioid receptor gene was supported as a target for genes within a top-ranked transcription factor network associated with level of methamphetamine intake. In addition, mice that consume high levels of methamphetamine were found to possess a nonfunctional form of the trace amine-associated receptor 1 (TAAR1). The Taar1 gene is within a mouse chromosome 10 quantitative trait locus for methamphetamine consumption, and TAAR1 function determines sensitivity to aversive effects of methamphetamine that may curb intake. The genes, gene interaction partners, and protein products identified in this genetic mouse model represent treatment target candidates for methamphetamine addiction.

Medications between psychiatric and addictive disorders

INTRODUCTION

Many epidemiological studies have revealed a frequent co-occurrence of psychiatric and substance use disorders. The term used in the literature to refer to this co-occurrence is dual diagnosis. The high prevalence of dual diagnosis has led physicians to observe the effects of medication prescribed to treat psychiatric disorders on the co-occurring substance use disorder and vice versa. The concept of medications between psychiatric and addictive disorders stems from these clinical observations, alongside which, however, it has developed from the observation that both psychiatric and substance use disorders share common neurobiological pathways and trigger common cognitive disorders. This has led researchers to develop medications on the basis of neurobiological and cognitive rationales.

MATERIAL AND METHOD

In our article, we review peculiar medications based on neurobiological and cognitive rationales and that have an impact in both psychiatric and addictive disorders.

RESULTS

We highlight how interesting these new prescriptions are for clinical observation and for the treatment of patients suffering from dual diagnosis.

CONCLUSION

We then go on to discuss the interest in them from the perspective of clinical practice and clinical research, in that the development of medications to treat dual diagnosis helps to further our knowledge of both psychiatric and substance use disorders.

Mirtazapine-induced acute angle closure

Acute angle closure (AAC) is an ocular emergency with symptoms including blurred vision, eye pain, headache, nausea, vomiting and reddening of the eye those results from increased intraocular pressure. This clinical condition can lead to permanent damage in vision, thus causing blindness by generating progressive and irreversible optic neuropathy if left untreated. There are several reasons of AAC, including several types of local and systemic medications; mainly sympathomimetics, cholinergics, anti-cholinergics, mydriatics, anti-histamines, antiepileptics like topiramate, tricyclic and tetracyclic antidepressants, serotonin reuptake inhibitors, antipsychotics, sulfa-based drugs and anticoagulants. Mirtazapine, a noradrenergic and specific serotonergic antidepressant, is an atypical antidepressant with a complex pharmacological profile. This case report describes a patient with major depressive disorder, who experienced AAC after the first dosage of mirtazapine treatment, and highlights the importance of close monitoring of individuals under antidepressant treatment particularly immediately after initiation of the drug.

A new approach to assess gambling-like behavior in laboratory rats: using intracranial self-stimulation as a positive reinforcer

Pathological gambling is one manifestation of impulse control disorders. The biological underpinnings of these disorders remain elusive and treatment is far from ideal. Animal models of impulse control disorders are a critical research tool for understanding this condition and for medication development. Modeling such complex behaviors is daunting, but by its deconstruction, scientists have recapitulated in animals critical aspects of gambling. One aspect of gambling is cost/benefit decision-making wherein one weighs the anticipated costs and expected benefits of a course of action. Risk/reward, delay-based and effort-based decision-making all represent cost/benefit choices. These features are studied in humans and have been translated to animal protocols to measure decision-making processes. Traditionally, the positive reinforcer used in animal studies is food. Here, we describe how intracranial self-stimulation can be used for cost/benefit decision-making tasks and overview our recent studies showing how pharmacological therapies alter these behaviors in laboratory rats. We propose that these models may have value in screening new compounds for the ability to promote and prevent aspects of gambling behavior.

Using conditioned place preference to identify relapse prevention medications

Stimuli, including contexts, which predict the availability or onset of a drug effect, can acquire conditioned incentive motivational properties. These conditioned properties endure after withdrawal, and can promote drug-seeking which may result in relapse. Conditioned place preference (CPP) assesses the associations between drugs and the context in which they are experienced. Here, we review the potential utility of CPP procedures in rodents and humans to evaluate medications that target conditioned drug-seeking responses. We discuss the translational potential of the CPP procedure from rodents to humans, and review findings with FDA-approved treatments that support the use of CPP to develop relapse-reduction medications. We also discuss challenges and methodological questions in applying the CPP procedure to this purpose. We argue that an efficient and valid CPP procedure in humans may reduce the burden of full clinical trials with drug-abusing patients that are currently required for testing promising treatments.

Methylphenidate vs. resperidone in treatment of methamphetamine dependence: A clinical trial

BACKGROUND AND AIMS

Currently, there is no widely accepted evidence-based pharmacotherapy regime for the treatment of psychostimulant dependence. Yet, different pharmacological approaches have been tried in the treatment of MA addiction. The present study was conducted to compare efficiency of methylphenidate which is relatively easily accessible in our country, with resperidone for this purpose.

METHODS

Eighty-six patients with MA dependence according to criteria defined by DSM IV-TR were divided into two groups. Patients in group R were given oral resperidone 1 mg daily for 1 week; then 2 mg daily in a divided dose for 3 weeks. Patients in group M were given oral methylphenidate 10 mg daily for 2 weeks, 7.5 mg daily for 1 week, then 5 mg daily for 1 week. They were evaluated for drug craving, psychological, neurologic and somatic symptoms at the start and end of the study.

FINDINGS

Both drugs were useful for lowering drug craving in patients; however resperidone was more effective (6.31 ± 8.31 vs.19.6 ± 12.45 cravings per week, respectively). The effects of resperidone were more notable in lowering frequency and intensity of psychiatric, neurologic, cardiac and somatic symptoms of the patients after discontinuation of MA abuse; however methylphenidate was effective too; though with a lower potency.

CONCLUSION

The present study confirmed that both methylphenidate and resperidone can successfully be used for treatment of MA dependence, in order to reduce drug craving and psychological, neurologic, and somatic problems in patients. However, the efficacy of methylphenidate was estimated to be less than that of resperidone for this purpose.