Treatment of primary insomnia with trimipramine: an alternative to benzodiazepine hypnotics?

Alliance for Sleep Clinical Practice Guideline on Switching or Deprescribing Hypnotic Medications for Insomnia

Determining the most effective insomnia medication for patients may require therapeutic trials of different medications. In addition, medication side effects, interactions with co-administered medications, and declining therapeutic efficacy can necessitate switching between different insomnia medications or deprescribing altogether. Currently, little guidance exists regarding the safest and most effective way to transition from one medication to another. Thus, we developed evidence-based guidelines to inform clinicians regarding best practices when deprescribing or transitioning between insomnia medications. Five U.S.-based sleep experts reviewed the literature involving insomnia medication deprescribing, tapering, and switching and rated the quality of evidence. They used this evidence to generate recommendations through discussion and consensus. When switching or discontinuing insomnia medications, we recommend benzodiazepine hypnotic drugs be tapered while additional CBT-I is provided. For Z-drugs zolpidem and eszopiclone (and not zaleplon), especially when prescribed at supratherapeutic doses, tapering is recommended with a 1–2-day delay in administration of the next insomnia therapy when applicable. There is no need to taper DORAs, doxepin, and ramelteon. Lastly, off-label antidepressants and antipsychotics used to treat insomnia should be gradually reduced when discontinuing. In general, offering individuals a rationale for deprescribing or switching and involving them in the decision-making process can facilitate the change and enhance treatment success.

Antidepressant Withdrawal and Rebound Phenomena

BACKGROUND

Antidepressants are among the most commonly prescribed drugs worldwide. They are often discontinued, frequently without the knowledge of the prescribing physician. It is, therefore, important for physicians to be aware of the withdrawal and rebound phenomena that may arise, in order to prevent these phenomena, treat them when necessary, and counsel patients appropriately.

METHODS

This review is based on a comprehensive, structured literature search on antidepressant withdrawal phenomena that we carried out in the CENTRAL, PubMed (Medline), and Embase databases. We classified the relevant publications and reports by their methodological quality.

RESULTS

Out of a total of 2287 hits, there were 40 controlled trials, 38 cohort studies and retrospective analyses, and 271 case reports that met the inclusion criteria. Withdrawal manifestations are usually mild and self-limiting; common ones include dizziness, headache, sleep disturbances, and mood swings. More serious or pro- longed manifestations rarely arise. There is an increased risk with MAO inhibitors, tricyclic antidepressants, venlafaxine, and paroxetine; on the other hand, for agome- latine and fluoxetine, abrupt discontinuation seems to be unproblematic. There is also some evidence of rebound phenomena, i.e., of higher relapse rates or especially severe relapses of depression after the discontinuation of an anti- depressant.

CONCLUSION

A robust evidence base now indicates that there can be acute with- drawal phenomena when antidepressants are discontinued. Putative rebound phenomena have not been adequately studied to date. It is recommended that antidepressants should be tapered off over a period of more than four weeks.

Sleep Pharmacogenetics: The Promise of Precision Medicine

Pharmacogenetics is the branch of personalized medicine concerned with the variability in drug response occurring because of heredity. Advances in genetics research, and decreasing costs of gene sequencing, are promoting tremendous growth in pharmacogenetics in all areas of medicine, including sleep medicine. This article reviews the body of research indicating that there are genetic variations that affect the therapeutic actions and adverse effects of agents used for the treatment of sleep disorders to show the potential of pharmacogenetics to improve the clinical practice of sleep medicine.

Clinical Practice Guideline for the Pharmacologic Treatment of Chronic Insomnia in Adults: An American Academy of Sleep Medicine Clinical Practice Guideline

INTRODUCTION

The purpose of this guideline is to establish clinical practice recommendations for the pharmacologic treatment of chronic insomnia in adults, when such treatment is clinically indicated. Unlike previous meta-analyses, which focused on broad classes of drugs, this guideline focuses on individual drugs commonly used to treat insomnia. It includes drugs that are FDA-approved for the treatment of insomnia, as well as several drugs commonly used to treat insomnia without an FDA indication for this condition. This guideline should be used in conjunction with other AASM guidelines on the evaluation and treatment of chronic insomnia in adults.

METHODS

The American Academy of Sleep Medicine commissioned a task force of four experts in sleep medicine. A systematic review was conducted to identify randomized controlled trials, and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) process was used to assess the evidence. The task force developed recommendations and assigned strengths based on the quality of evidence, the balance of benefits and harms, and patient values and preferences. Literature reviews are provided for those pharmacologic agents for which sufficient evidence was available to establish recommendations. The AASM Board of Directors approved the final recommendations.

RECOMMENDATIONS

The following recommendations are intended as a guideline for clinicians in choosing a specific pharmacological agent for treatment of chronic insomnia in adults, when such treatment is indicated. Under GRADE, a STRONG recommendation is one that clinicians should, under most circumstances, follow. A WEAK recommendation reflects a lower degree of certainty in the outcome and appropriateness of the patient-care strategy for all patients, but should not be construed as an indication of ineffectiveness. GRADE recommendation strengths do not refer to the magnitude of treatment effects in a particular patient, but rather, to the strength of evidence in published data. Downgrading the quality of evidence for these treatments is predictable in GRADE, due to the funding source for most pharmacological clinical trials and the attendant risk of publication bias; the relatively small number of eligible trials for each individual agent; and the observed heterogeneity in the data. The ultimate judgment regarding propriety of any specific care must be made by the clinician in light of the individual circumstances presented by the patient, available diagnostic tools, accessible treatment options, and resources. We suggest that clinicians use suvorexant as a treatment for sleep maintenance insomnia (versus no treatment) in adults. (WEAK). We suggest that clinicians use eszopiclone as a treatment for sleep onset and sleep maintenance insomnia (versus no treatment) in adults. (WEAK). We suggest that clinicians use zaleplon as a treatment for sleep onset insomnia (versus no treatment) in adults. (WEAK). We suggest that clinicians use zolpidem as a treatment for sleep onset and sleep maintenance insomnia (versus no treatment) in adults. (WEAK). We suggest that clinicians use triazolam as a treatment for sleep onset insomnia (versus no treatment) in adults. (WEAK). We suggest that clinicians use temazepam as a treatment for sleep onset and sleep maintenance insomnia (versus no treatment) in adults. (WEAK). We suggest that clinicians use ramelteon as a treatment for sleep onset insomnia (versus no treatment) in adults. (WEAK). We suggest that clinicians use doxepin as a treatment for sleep maintenance insomnia (versus no treatment) in adults. (WEAK). We suggest that clinicians not use trazodone as a treatment for sleep onset or sleep maintenance insomnia (versus no treatment) in adults. (WEAK). We suggest that clinicians not use tiagabine as a treatment for sleep onset or sleep maintenance insomnia (versus no treatment) in adults. (WEAK). We suggest that clinicians not use diphenhydramine as a treatment for sleep onset and sleep maintenance insomnia (versus no treatment) in adults. (WEAK). We suggest that clinicians not use melatonin as a treatment for sleep onset or sleep maintenance insomnia (versus no treatment) in adults. (WEAK). We suggest that clinicians not use tryptophan as a treatment for sleep onset or sleep maintenance insomnia (versus no treatment) in adults. (WEAK). We suggest that clinicians not use valerian as a treatment for sleep onset or sleep maintenance insomnia (versus no treatment) in adults. (WEAK).

Optimizing the Pharmacologic Treatment of Insomnia: Current Status and Future Horizons

A number of medications are available for treating patients with insomnia. These medications include agents approved as insomnia therapies by the U.S. Food and Drug Administration (FDA), agents approved by the FDA for another condition that are used "off-label" to treat insomnia, and agents available "over-the-counter" that are taken by individuals with insomnia. These agents differ in their properties, their safety and efficacy when used for different insomnia patient subtypes, and the available data on their efficacy and safety in these subtypes. As a result, optimizing the medication treatment of insomnia for a given patient requires that the clinician select an agent for use which has characteristics that make it most likely to effectively and safely address the type of sleep difficulty experienced by that individual. This article is intended to assist clinicians and researchers in carrying out this optimization. It begins by reviewing the basic characteristics of the medications used to treat insomnia. This is followed by a review of the fundamental ways that individuals with insomnia may differ and affect the choice of medication therapy. This review includes discussions that illustrate how to best choose a medication based on the characteristics of the available medications, the key differences among insomnia patients, and the available research literature. Lastly, we discuss future directions for the optimizing pharmacologic management of insomnia. It is hoped that the treatment tailoring methods discussed herein serve as a means of improving the clinical management of insomnia and, thus, improve the lives of the many patients who suffer from this common and impairing condition.

Psychiatric disorders and sleep

There is growing experimental evidence that the relationship between psychiatric disorders and sleep is complex and includes bidirectional causation. This article provides the evidence that supports this point of view, reviewing data on sleep disturbances seen in patients with psychiatric disorders as well as data on the impact of sleep disturbances on psychiatric conditions. Although much has been learned about the psychiatric disorders-sleep relationship, additional research is needed to better understand the relationship. Such work promises to improve comprehension of these phenomena and lead to better treatment for the many patients with sleep disorders and psychiatric disorders.

Pharmacotherapy of insomnia

INTRODUCTION

Insomnia is one of the most prevalent sleep disorders in developed countries, being surpassed only by chronic sleep deprivation. Patients with insomnia tend to have an altered quality of life, impaired daytime functioning and an increased risk of work accidents and motor vehicle crashes. Insomnia is commonly associated with chronic medical conditions, metabolic illnesses and mental disorders (such as depression and anxiety), with which there is a dual, reciprocal relationship.

AREAS COVERED

This paper focuses on current pharmacotherapy options for the treatment of insomnia, particularly benzodiazepine receptor agonists, which nowadays represent the mainstay of hypnotic therapy. The melatonin receptor antagonist, ramelteon, is reviewed (an alternative for some patients with only sleep-onset difficulty), as are sedating antidepressants, which are commonly used 'off-label' to treat insomnia, despite limited efficacy data and potential significant safety concerns. Orexin (OX) antagonists are also discussed, especially those that block OX2 or both OX1 and OX2 receptors, as these are the most promising new agents for the treatment of insomnia, with encouraging results in preliminary clinical trials.

EXPERT OPINION

Research to evaluate and formulate treatments for insomnia is often complicated by the fact that insomnia is usually of multifactorial etiology. Understanding the molecular and receptor mechanisms involved in promoting sleep in varied disorders could provide future approaches in new drug development. In the long term, more randomized controlled trials are needed to assess both short-term and long-term effects of these medications and their efficacy in comorbid diseases that affect sleep quality or quantity.

Prevalence and factors associated with off-label antidepressant prescriptions for insomnia

Background:

The primary objective of our study was to investigate the prevalence of off-label antidepressant drug use in insomnia. The secondary objective was to compare prescribing patterns between off-label antidepressants vs hypnotics approved by the US Food and Drug Administration for insomnia, with particular emphasis on socioeconomic characteristics of patients and physicians.

Methods:

We undertook a secondary data analysis using the national longitudinal database from the 2006 National Ambulatory Medical Care Survey. Subjects were identified from outpatient visits in which at least one insomnia drug was prescribed. A series of weighted Chi-squared statistics was used to compare drug use for insomnia across various patient and physician characteristics. Multivariate logistic regression was conducted to identify factors associated with off-label antidepressant drug use.

Results:

Among 901.95 million outpatient visits that took place in the US in 2006, an estimated 30.43 million visits included at least one drug prescription for insomnia. Off-label antidepressants were prescribed significantly more frequently (45.1%) than nonbenzodiazepine z-hypnotics (43.2%) and benzodiazepines (11.7%). Insomnia prescribing patterns were significantly influenced by physician specialty and physician office settings. Pediatricians (odds ratio [OR]: 65.892; 95% confidence interval [CI]: 5.536–810.564) and neurologists (OR: 4.784; 95% CI: 2.044–11.201) were more likely to prescribe off-label antidepressants than psychiatrists. Self-paying patients were more likely to receive off-label antidepressants as treatment for insomnia than patients with private insurance (OR 2.594; 95% CI: 1.128–5.967).

Conclusion:

Our findings indicate significant socioeconomic disparities in the use of off-label antidepressants. Future studies might explore interventional and educational strategies to ensure well informed clinical decisions that can withstand pharmaceutical marketing strategies and diagnostic uncertainties regarding the treatment of insomnia.

The effect of trimipramine on dream recall and dream emotions in depressive outpatients

Trimipramine is a sedating tricyclic antidepressant which is not only effective in the treatment of depression but also in primary insomnia. In contrast to most other antidepressants, trimipramine does not affect rapid eye movement sleep. In a large sample of depressive outpatients (N = 3926), the effect of trimipramine on dream recall and dream emotions was studied. The effect of trimipramine on dream recall was small and might be explained by the reduction of negatively toned dreams. The 4-week treatment with trimipramine yielded a considerable shift in dream emotions towards the positive end of the scale, which is paralleled by the decrease of symptom severity. The present findings support the continuity hypothesis of dreaming by demonstrating a close link between waking-life symptomatolgy and negative dream emotions. Future studies should analyze dream content in order to support the hypothesis that improvement in day-time symptoms is reflected in patients' dreams.

Pharmacologic management of insomnia: past, present, and future

Views on the etiology and morbidities associated with insomnia are evolving and affect clinicians' approach to the pharmacologic management of insomnia. Currently, benzodiazepine receptor agonists (BzRAs) and a single melatonin receptor agonist are recognized as safe and efficacious hypnotics. Variability in BzRAs, pharmacokinetics, and manipulation of dose provide clinicians with options that meet the needs of most patients. Other drugs (eg, sedating antidepressants) also are used commonly in clinical practice to treat insomnia, but evidence is lacking to support this most cases. Improvement in managing insomnia will result from systematic research with these drugs, with drugs in development, and with novel uses, such as co-therapy.

Paroxetine treatment of primary insomnia in older adults

OBJECTIVE

The goal of this study was to test the efficacy of paroxetine for primary insomnia in older adults.

METHODS

Adults over age 55 with primary insomnia were randomly assigned to six weeks of double-blind treatment with paroxetine (N = 14) or placebo (N = 13). Outcome measures included persistence or resolution of insomnia; weekly diary measures of sleep quality, daytime alertness, and mood; and pre-/postpolysomnographic measures of sleep latency, wake time after sleep onset, and sleep efficiency.

RESULTS

Although weekly diary-based measures showed improved subjective sleep quality, daytime alertness, and mood with paroxetine, the authors observed no effect on sleep efficiency or categorical response rates.

CONCLUSION

Paroxetine appears to be ineffective for treating primary insomnia in old age.

Insomnia

Effective management of insomnia begins with recognition and adequate assessment. Family doctors and other health care providers such as practice nurses and psychologists should routinely enquire about sleep habits as a component of overall health assessment. Identification and treatment of primary psychiatric disorders, medical conditions, circadian disorders, or specific physiological sleep disorders--eg, sleep apnoea and periodic limb movement disorder--are essential steps in management of insomnia. Conditioned aspects of insomnia can be primary (psychophysiological insomnia) or may complicate sleep disturbance owing to other causes. Approved hypnotic drugs have clearly been shown to improve subjective and objective sleep measures in various short-term situations. Despite widespread use of standard hypnotics and sedating antidepressants for chronic insomnia, their role for this indication still remains to be further defined by research evidence. Non-pharmacological treatments, particularly stimulus control and sleep restriction, are effective for conditioned aspects of insomnia and are associated with durable long-term improvement in sleep.

The sleep-improving effects of doxepin are paralleled by a normalized plasma cortisol secretion in primary insomnia. A placebo-controlled, double-blind, randomized, cross-over study followed by an open treatment over 3 weeks

RATIONALE

In primary care, sedating antidepressants are often used for treating insomnia, although their underlying sleep-promoting mechanisms are only incompletely understood. Since enhanced evening and nocturnal plasma cortisol levels are supposed to maintain insomniac sleep complaints, a functional link between sleep and cortisol secretion in the mode of action of antidepressants in insomnia might be suspected.

OBJECTIVES

We therefore investigated the effects of the tricyclic antidepressant doxepin on nocturnal sleep and plasma cortisol concentration in ten patients (age 41.3+/-9.5 years) with chronic primary insomnia between 1700 hours and 0800 hours.

METHODS

Single infusions of placebo and 25 mg doxepin were applied following a double-blind, randomized cross-over design. Afterward, all patients received 25 mg doxepin p.o. for 3 weeks in an open-study design.

RESULTS

Both doxepin application forms improved sleep significantly and reduced mean cortisol levels from 9.0+/-1.7 microg/l (single placebo i.v.) to 7.5+/-1.6 microg/l (single doxepin i.v.) or 7.6+/-2.0 microg/l (subchronic doxepin p.o.). The duration of the quiescent period of the cortisol rhythm was significantly prolonged following both doxepin administrations compared with placebo.

CONCLUSIONS

The results implicate that the sleep-improving effects of doxepin are mediated at least in part by a normalization of hypothalamic-pituitary-adrenal axis functions. Although in some patients rebound insomnia and specific side effects must be considered, our findings give a further rationale for the use of antidepressants in the treatment of primary insomnia.

Are there gender differences in objective and subjective sleep measures? A study of insomniacs and healthy controls

It is well known that insomnia is more frequent in women than in men throughout all age groups. In this respect insomnia resembles other psychiatric disorders that occur more frequently in women such as anxiety and depressive disorders. Since insomnia is frequently a symptom of anxiety and depression, it remains an open question whether the comorbidity with psychiatric disorders fully explains the gender differences in the prevalence of insomnia or whether gender influences sleep independently from psychiatric conditions. We analyzed sleep measures of patients diagnosed with a primary insomnia (n=86) and of an age- and sex-matched healthy control group (n=86) by polysomnography; additionally, subjective rating scales were available for 70 patients and 54 controls matched for mean age and sex ratio. Surprisingly, none of the sleep continuity measures (sleep duration, sleep efficiency, arousal index, and wake%), nor slow wave or REM sleep % showed significant gender differences in both insomniacs and healthy controls. Also, subjective estimates of sleep quality were comparable in both sexes. As expected, insomniacs strongly differed from the control group in all subjective measures of sleep. Polysomnography showed significantly reduced sleep duration and efficiency, increased arousal index, and slightly, but significantly, less REM sleep in the insomniacs as compared to the healthy controls. These studies indicate that gender seems to have, if any, relatively little influence on sleep per se. We hypothesize that the clear gender differences in the prevalence of insomnia are caused predominantly by gender differences in the prevalence of anxiety and depression. Primary insomnia may be, at least in a part of the cases, a subclinical or subthreshold form of anxiety or depression.

Effects of polymorphisms in CYP2D6, CYP2C9, and CYP2C19 on trimipramine pharmacokinetics

Little is known about the impact of cytochrome P450 polymorphisms on the metabolism of trimipramine, which is still widely used as antidepressant due to its positive effect on sleep patterns. A single oral dose of 75 mg trimipramine was given to 42 healthy volunteers selected according to their CYP2D6, CYP2C19, and CYP2C9 genotypes. The reference group included 8 subjects with homozygous active wild-type genotypes of all 3 enzymes (EM). This group was compared with 7 intermediate (IM) with 1 and 7 poor metabolizers (PM) with zero active alleles of CYP2D6 and CYP2C19, respectively, and with 4 subjects with the genotype CYP2C9*3/*3. Pharmacokinetics of trimipramine and its demethylated metabolite strongly depended on the CYP2D6 genotype. Median oral clearance of trimipramine was 276 L/h (range 180-444) in the reference group but only 36 L/h (range 24-48) in CYP2D6 PMs (P < 0.001). These differences could only be explained by an effect of CYP genotypes on both parameters, systemic clearance and bioavailability, the latter being at least 3-fold higher in CYP2D6 PMs than in the reference group. The desmethyltrimipramine area under the concentration-time curve was 40-fold greater in CYP2D6 PMs than in the reference group (1.7 vs. 0.04 mg/L x h in EMs), but below the quantification limit in most carriers of deficiencies of CYP2C19 or CYP2C9. This indicates that both CYP2C enzymes contribute to the demethylation of desmethyltrimipramine and CYP2D6 to further metabolism.

Sleep, the hypothalamic-pituitary-adrenal axis, and cytokines: multiple interactions and disturbances in sleep disorders

Sleep is an important component of mammalian homeostasis, vital for survival. Sleep disorders are common in the general population and are associated with significant medical, psychologic, and social disturbances. Sleep, in particular deep sleep, has an inhibitory influence on the HPA axis, whereas activation of the HPA axis or administration of glucocorticoids can lead to arousal and sleeplessness. Insomnia, the most common sleep disorder, is associated with a 24-hour increase of ACTH and cortisol secretion, consistent with a disorder of central nervous system hyperarousal. Sleepiness and fatigue are very prevalent in the general population, and recent studies have demonstrated that the proinflammatory cytokines IL-6 and/or TNF-alpha are elevated in disorders associated with excessive daytime sleepiness, such as sleep apnea, narcolepsy, and idiopathic hypersomnia. Sleep deprivation leads to sleepiness and daytime hypersecretion of IL-6. Combined, these findings suggest that the HPA axis stimulates arousal, while IL-6 and TNF-alpha are possible mediators of excessive daytime sleepiness in humans.

Chronic insomnia is associated with nyctohemeral activation of the hypothalamic-pituitary-adrenal axis: clinical implications

Although insomnia is, by far, the most commonly encountered sleep disorder in medical practice, our knowledge in regard to its neurobiology and medical significance is limited. Activation of the hypothalamic-pituitary-adrenal axis leads to arousal and sleeplessness in animals and humans; however, there is a paucity of data regarding the activity of the hypothalamic-pituitary-adrenal axis in insomniacs. We hypothesized that chronic insomnia is associated with increased plasma levels of ACTH and cortisol. Eleven young insomniacs (6 men and 5 women) and 13 healthy controls (9 men and 4 women) without sleep disturbances, matched for age and body mass index, were monitored in the sleep laboratory for 4 consecutive nights, whereas serial 24-h plasma measures of ACTH and cortisol were obtained during the fourth day. Insomniacs, compared with controls, slept poorly (significantly higher sleep latency and wake during baseline nights). The 24-h ACTH and cortisol secretions were significantly higher in insomniacs, compared with normal controls (4.2 +/- 0.3 vs. 3.3 +/- 0.3 pM, P = 0.04; and 218.0 +/- 11.0 vs. 190.4 +/- 8.3 nM, P = 0.07). Within the 24-h period, the greatest elevations were observed in the evening and first half of the night. Also, insomniacs with a high degree of objective sleep disturbance (% sleep time < 70), compared with those with a low degree of sleep disturbance, secreted a higher amount of cortisol. Pulsatile analysis revealed a significantly higher number of peaks per 24 h in insomniacs than in controls (P < 0.05), whereas cosinor analysis showed no differences in the temporal pattern of ACTH or cortisol secretion between insomniacs and controls. We conclude that insomnia is associated with an overall increase of ACTH and cortisol secretion, which, however, retains a normal circadian pattern. These findings are consistent with a disorder of central nervous system hyperarousal rather than one of sleep loss, which is usually associated with no change or decrease in cortisol secretion or a circadian disturbance. Chronic activation of the hypothalamic-pituitary-adrenal axis in insomnia suggests that insomniacs are at risk not only for mental disorders, i.e. chronic anxiety and depression, but also for significant medical morbidity associated with such activation. The therapeutic goal in insomnia should be to decrease the overall level of physiologic and emotional arousal, and not just to improve the nighttime sleep.

The diagnosis of primary insomnia and treatment alternatives

This review provides information about the diagnosis and treatment of primary insomnia. Several treatment strategies are reviewed including the use of hypnotics, naturopathic remedies and behavioral interventions. We suggest that nonpharmacologic interventions are likely to be the most safe and effective.

New trends in insomnia management

Pharmacological management of insomnia is continually evolving. The introduction of non-benzodiazepine benzodiazepine receptor agonist hypnotics provides an opportunity to understand different patterns of pharmacological activity with mechanistic differences in receptor activity. The impact of insomnia on daytime functioning and long-term health and socioeconomic status has been recognized. Epidemiological studies indicate that insomnia is associated with increased absenteeism and healthcare costs (although the latter appear to be partly attributable to comorbid depression). It will thus be important to determine whether hypnotics, in addition to their effects on sleep, provide other benefits for the patient that are related to these parameters. The successful resolution of this issue will require the adoption of additional outcome measures, such as effects on quality of life and healthcare costs. Recognition that long-term hypnotic use is widespread among insomniacs has prompted proposals for alternative prescribing patterns. Although certain hypnotics appear to be free of tolerance on prolonged use, caution is required in the long-term use of any hypnotic because of the lack of systematic data on chronic efficacy and safety. Therefore, alternative administration schedules (e.g. intermittent and 'as required') are being investigated. These may have very different consequences in terms of abuse liability and patients' perceptions of efficacy, and thus permit a more effective and appropriate use of this drug class.

Trimipramine: a challenge to current concepts on antidepressives

Although it is chemically a classical tricyclic antidepressant agent, trimipramine shows atypical pharmacological properties. Its well-documented antidepressant action cannot be explained by noradrenaline or serotonin reuptake inhibition or by a down-regulation of beta-adrenoceptors. Furthermore, its receptor affinity profile resembles more that of clozapine, a neuroleptic drug, than that of tricyclic antidepressants. Trimipramine does not reduce, but rather increases, rapid eye movement sleep. It stimulates nocturnal prolactin secretion and inhibits nocturnal cortisol secretion and may act at the level of the hypothalamus on corticotropin-releasing hormone secretion. Trimipramine is of particular value in depressed patients with insomnia, and it has been shown to be effective in the therapy of primary insomnia. As the pharmacological profile indicates, and an open clinical study has shown, trimipramine might also be active as an antipsychotic. The drug is both a tool for increasing our understanding of depression and a potential therapy for several psychiatric disorders.