Mirtazapine: only for depression?

Use of mirtazapine in the treatment of canine behaviour problems: A review of 32 cases

BACKGROUND

Canine behaviour problems seen by speciality behavioural medicine services often involve chronic anxiety disorders that have resulted in maladaptation of the individual to its environment. Common stressors include the presence of other individuals (other dogs or people), noise and being alone. The treatment of these behavioural problems usually includes a combination of behaviour modification, environmental modification and biological therapies. Within the latter, anxiolytic drugs such as clomipramine or fluoxetine have proven useful.

METHODS

Here, we present a retrospectively analysed series of 32 cases that were treated with the anxiolytic drug mirtazapine, which is widely used in human medicine but has not previously been reported for the treatment of behavioural problems in dogs (although it is marketed as an appetite stimulant in cats). Cases included dogs with a range of anxiety-related behavioural problems.

RESULTS

Eighty-one percent of dogs that presented with a behavioural problem showed improvement and suspected adverse effects were mild and tolerable.

LIMITATIONS

Further studies are required to isolate this result from the other therapeutic measures and to compare its efficacy with other drugs.

CONCLUSION

Mirtazapine appears to be a suitable and safe option for the treatment of anxiety-related behavioural problems in dogs.

In silico identification of the rare-coding pathogenic mutations and structural modeling of human NNAT gene associated with anorexia nervosa

PURPOSE

Increased susceptibility towards anorexia nervosa (AN) was reported with reduced levels of neuronatin (NNAT) gene. We sought to investigate the most pathogenic rare-coding missense mutations, non-synonymous single-nucleotide polymorphisms (nsSNPs) of NNAT and their potential damaging impact on protein function through transcript level sequence and structure based in silico approaches.

METHODS

Gene sequence, single nucleotide polymorphisms (SNPs) of NNAT was retrieved from public databases and the putative post-translational modification (PTM) sites were analyzed. Distinctive in silico algorithms were recruited for transcript level SNPs analyses and to characterized high-risk rare-coding nsSNPs along with their impact on protein stability function. Ab initio 3D-modeling of wild-type, alternate model prediction for most deleterious nsSNP, validation and recognition of druggable binding pockets were also performed. AN 3D therapeutic compounds that followed rule of drug-likeness were docked with most pathogenic variant of NNAT to estimate the drugs' binding free energies.

RESULTS

Conclusively, 10 transcript (201-205)-based nsSNPs from 3 rare-coding missense variants, i.e., rs539681368, rs542858994, rs560845323 out of 840 exonic SNPs were identified. Transcript-based functional impact analyses predicted rs539681368 (C30Y) from NNAT-204 as the high-risk rare-coding pathogenic nsSNP, deviating protein functions. The 3D-modeling analysis of AN drugs' binding energies indicated lowest binding free energy (ΔG) and significant inhibition constant (K_i) with mutant models C30Y.

CONCLUSIONS

Mutant model (C30Y) exhibiting significant drug binding affinity and the commonest interaction observed at the acetylation site K59. Thus, based on these findings, we concluded that the identified nsSNP may serve as potential targets for various studies, diagnosis and therapeutic interventions.

LEVEL OF EVIDENCE

No level of evidence-open access bioinformatics research.

Off-label use of antidepressants, antipsychotics, and mood-stabilizers in psychiatry

Off-label drug prescribing in psychiatry is increasing. Many psychotropic drugs are approved for psychopathologic syndromes rather than based on international standard diagnostic classification systems which might facilitate the clinical decision for off-label prescriptions. The objective of this study was to analyze the prevalence and category of off-label use of psychotropic drugs. The study was conducted in 10 psychiatric hospitals in Germany over a period of 2 years. Prescription data of all patients were retrospectively analyzed after identification of antidepressants, antipsychotics, and mood-stabilizers, which were classified as off-label according to the German prescribing information and diagnostic classification according to ICD-10. In total, 53,909 patient cases (46% female) with a mean age of 46.8 (SD: 18) years were included in the study. 30.2% of the cases received at least one off-label prescription of a psychotropic drug during hospital stay. Off-label prevalence rates differed markedly between different diagnostic groups (ICD-10 F0/G3: 47%, F1: 33%, F2: 25%, F3: 21%, F4: 27%, F6: 46%, F7: 84%). The most often off-label prescribed drugs were quetiapine and mirtazapine for organic mental disorders (F0/G3), valproate and quetiapine in patients with disorders due to psychoactive substance use (F1), valproate in patients with psychotic disorders (F2), and risperidone and olanzapine in patients with affective disorders (F3). The prevalence rate of psychotropic off-label prescriptions is high if restricted to product description and ICD-10 diagnosis. Therefore, current psychiatric guidelines should drug-specifically issue this problem by defining psychiatric off-label indications based on a clear benefit-risk assessment.

Mirtazapine in schizophrenia - an undeservedly overlooked option?

Mirtazapine has often been prescribed as add-on treatment for schizophrenia in patients with suboptimal response to conventional treatments. In this review, we evaluate the existing evidence for efficacy and effectiveness of add-on mirtazapine in schizophrenia and reappraise the practical and theoretical aspects of mirtazapine-antipsychotic combinations. In randomized controlled trials (RCTs), mirtazapine demonstrated favourable effects on negative and cognitive (although plausibly not depressive) symptoms, with no risk of psychotic exacerbation. Mirtazapine also may have a desirable effect on antipsychotic-induced sexual dysfunction, but seems not to alleviate extrapyramidal symptoms, at least if combined with second-generation antipsychotics. It is noteworthy that all published RCTs have been underpowered and relatively short in duration. In the only large pragmatic effectiveness study that provided analyses by add-on antidepressant, only mirtazapine was associated with both decreased rate of hospital admissions and number of in-patient days. Mirtazapine hardly affects the pharmacokinetics of antipsychotics. However, possible pharmacodynamic interactions (sedation and metabolic offence) should be borne in mind. The observed desired clinical effects of mirtazapine may be due to its specific receptor-blocking properties. Alternative theoretical explanations include its possible neuroprotective effect. Further well-designed RCTs and real-world effectiveness studies are needed to determine whether add-on mirtazapine should be recommended for difficult-to-treat schizophrenia.

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.