Lofepramine. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in depressive illness

In silico analysis of the antidepressant fluoxetine and similar drugs as inhibitors of the human protein acid sphingomyelinase: a related SARS-CoV-2 inhibition pathway

Acid Sphingomyelinase (ASM) is a human phosphodiesterase that catalyzes the metabolism of sphingomyelin (SM) to ceramide and phosphocholine. ASM is involved in the plasma membrane cell repair and is associated with the lysosomal inner lipid membrane by nonbonding interactions. The disruption of those interaction would result in ASM release into the lysosomal lumen and consequent degradation of its structure. Furthermore, SARS-CoV-2 infection has been linked with ASM activation and with a ceramide domain formation in the outer leaflet of the plasma membrane that is thought to be crucial for the viral particles recognition by the host cells. In this study, we have explored in silico the behavior of fluoxetine and related drugs as potential inhibitors of ASM. Theoretically, these drugs would be able to overpass lysosomal membrane and reach the interactions that sustain ASM structure, breaking them and inhibiting the ASM. The analyses of docking data indicated that fluoxetine allocated mainly in the N-terminal saposin domain via nonbonding interactions, mostly of hydrophobic nature. Similar results were obtained for venlafaxine, citalopram, atomoxetine, nisoxetine and fluoxetine's main metabolite norfluoxetine. In conclusion, it was observed that the saposin allocation may be a good indicative of the drugs inhibition mechanism, once this domain is responsible for the binding of ASM to lysosomal membrane and some of those drugs have previously been reported to inhibit the phosphodiesterase by releasing its structure in the lysosomal lumen. Our MD data also provides some insight about natural ligand C18 sphingomyelin conformations on saposin.Communicated by Ramaswamy H. Sarma.

Fluoxetine Arrests Growth of the Model Diatom Phaeodactylum tricornutum by Increasing Oxidative Stress and Altering Energetic and Lipid Metabolism

Pharmaceutical residues impose a new and emerging threat to aquatic environments and its biota. One of the most commonly prescribed pharmaceuticals is the antidepressant fluoxetine, a selective serotonin re-uptake inhibitor that has been frequently detected, in concentrations up to 40 μg L^–1, in aquatic ecosystems. The present study aims to investigate the ecotoxicity of fluoxetine at environmentally relevant concentrations (0.3, 0.6, 20, 40, and 80 μg L^–1) on cell energy and lipid metabolism, as well as oxidative stress biomarkers in the model diatom Phaeodactylum tricornutum. Exposure to higher concentrations of fluoxetine negatively affected cell density and photosynthesis through a decrease in the active PSII reaction centers. Stress response mechanisms, like β-carotene (β-car) production and antioxidant enzymes [superoxide dismutase (SOD) and ascorbate peroxidase (APX)] up-regulation were triggered, likely as a positive feedback mechanism toward formation of fluoxetine-induced reactive oxygen species. Lipid peroxidation products increased greatly at the highest fluoxetine concentration whereas no variation in the relative amounts of long chain polyunsaturated fatty acids (LC-PUFAs) was observed. However, monogalactosyldiacylglycerol-characteristic fatty acids such as C16:2 and C16:3 increased, suggesting an interaction between light harvesting pigments, lipid environment, and photosynthesis stabilization. Using a canonical multivariate analysis, it was possible to evaluate the efficiency of the application of bio-optical and biochemical techniques as potential fluoxetine exposure biomarkers in P. tricornutum. An overall classification efficiency to the different levels of fluoxetine exposure of 61.1 and 88.9% were obtained for bio-optical and fatty acids profiles, respectively, with different resolution degrees highlighting these parameters as potential efficient biomarkers. Additionally, the negative impact of this pharmaceutical molecule on the primary productivity is also evident alongside with an increase in respiratory oxygen consumption. From the ecological point of view, reduction in diatom biomass due to continued exposure to fluoxetine may severely impact estuarine and coastal trophic webs, by both a reduction in oxygen primary productivity and reduced availability of key fatty acids to the dependent heterotrophic upper levels.

Treatment of multiple sclerosis with lofepramine, L-phenylalanine and vitamin B(12): mechanism of action and clinical importance: roles of the locus coeruleus and central noradrenergic systems

In a randomized, placebo-controlled double-blind trial a combination of lofepramine, phenylalanine and vitamin B(12) was found to be effective in relieving the symptoms of multiple sclerosis (MS). The effect occurred within 2-4 weeks, and improved all types of symptoms in all types of MS. The combination was also effective in relieving symptoms in patients with chronic pain and chronic fatigue. We hypothesize that the action of this combined therapy may relate to activation of the noradrenergic locus coeruleus/lateral tegmentum (LC/LT) system which has the potential to influence the functioning of large areas of the brain and spinal cord.

Conventional and new antidepressant drugs in the elderly

Depression in the elderly is nowadays a predominant health care problem, mainly due to the progressive aging of the population. It results from psychosocial stress, polypathology, as well as some biochemical changes which occur in the aged brain and can lead to cognitive impairments, increased symptoms from medical illness, higher utilization of health care services and increased rates of suicide and nonsuicide mortality. Therefore, it is very important to make an early diagnosis and a suitable pharmacological treatment, not only for resolving the acute episode, but also for preventing relapse and enhancing the quality of life. Age-related changes in pharmacokinetics and in pharmacodynamics have to be kept into account before prescribing an antidepressant therapy in an old patient. In this paper some of the most important and tolerated drugs in the elderly are reviewed. Tricyclic antidepressants have to be used carefully for their important side effects. Nortriptyline, amytriptiline, clomipramine and desipramine as well, seem to be the best tolerated tricyclics in old people. Second generation antidepressants are preferred for the elderly and those patients with heart disease as they have milder side effects and are less toxic in overdose and include the so called atypicals, such as selective serotonin reuptake inhibitors, serotonin noradrenalene reuptake inhibitors and noradrenaline reuptake inhibitors. Monoamine oxidase (MAO) inhibitors are useful drugs in resistant forms of depression in which the above mentioned drugs have no efficacy; the last generation drugs (reversible MAO inhibitors), such as meclobemide, seem to be very successful. Mood stabilizing drugs are widely used for preventing recurrences of depression and for preventing and treating bipolar illness. They include lithium, which is sometimes used especially to prevent recurrence of depression, even if its use is limited in old patients for its side effects, the anticonvulsants carbamazepine and valproic acid. Putative last generation mood stabilizing drugs include the dihydropyridine L-type calcium channel blockers and the anticonvulsants phenytoin, lamotrigine, gabapentin and topiramate, which have unique mechanisms of action and also merit further systematic study. Psychotherapy is often used as an adjunct to pharmacotherapy, while electroconvulsant therapy is used only in the elderly patients with severe depression, high risk of suicide or drug resistant forms.

Evidence-based guidelines for treating depressive disorders with antidepressants: a revision of the 1993 British Association for Psychopharmacology guidelines. British Association for Psychopharmacology

A revision of the British Association for Psychopharmacology guidelines for treating depressive disorders with antidepressants was undertaken in order to specify the scope and target of the guidelines and to update the recommendations based explicitly on the available evidence. A consensus meeting, involving experts in depressive disorders and their treatment, reviewed key areas and considered the strength of evidence and clinical implications. The guidelines were drawn up after extensive feedback from participants and interested parties. A literature review is given which identifies the quality of evidence followed by recommendations, the strength of which are based on the level of evidence. The guidelines cover the nature and detection of depressive disorders, acute treatment with antidepressant drugs, choice of drug versus alternative treatment, practical issues in prescribing, management when initial treatment fails, continuation treatment, maintenance treatment to prevent recurrence and stopping treatment.

Metabolism of tricyclic antidepressants

1. Despite the considerable advances in the treatments available for mood disorders over the past generation, tricyclic antidepressants (TCAs) remain an important option for the pharmacotherapy of depression. 2. The pharmacokinetics of TCAs are characterized by substantial presystemic first-pass metabolism, a large volume of distribution, extensive protein binding, and an elimination half-life averaging about 1 day (up to 3 days for protriptyline). 3. Clearance of tricyclics is dependent primarily on hepatic cytochrome P450 (CYP) oxidative enzymes. Although the activities of some P450 isoenzymes are largely under genetic control, they may be influenced by external factors, such as the concomitant use of other medications or substances. Patient variables, such as ethnicity and age, also affect TCA metabolism. The impact of gender and related reproductive issues is coming under increased scrutiny. 4. Metabolism of TCAs, especially their hydroxylation, results in the formation of active metabolites, which contribute to both the therapeutic and the adverse effects of these compounds. 5. Renal clearance of the polar metabolites of TCAs is reduced by normal aging, accounting for much of the increased risk of toxicity in older patients. 6. Knowledge of factors affecting the metabolism of TCAs can further the development and understanding of newer antidepressant medications.

An investigation of the antidepressant properties of lofepramine and its desmethylated metabolites in the forced swim and olfactory bulbectomized rat models of depression

The purpose of this study was to examine the metabolites of lofepramine (LOF), namely desipramine (DMI), desmethyl desipramine (DDMI) and desmethyl lofepramine (DML) in the forced swim and olfactory bulbectomized (OB) rat models of depression. In the first study, subacute treatment with DMI (10 mg/kg) and DML (20 mg/kg), but not LOF, reduced the immobility time in the forced swim test. In the "open field", chronic (14 day) treatment with all drugs attenuated the hyperactivity associated with olfactory bulbectomy. In the second experiment, a lower dose of DML (10 mg/kg) demonstrated activity following subacute treatment in the forced swim and following chronic treatment in the OB model. In addition, DDMI (10 mg/kg) was active in both models. From these results, it can be concluded that, at the doses employed, LOF and it's desmethylated metabolites, DMI, DML and DDMI, exhibits activity in the OB model. In contrast, lofepramine but not it's desmethylated derivatives is inactive in the forced swim test, perhaps suggesting the requirement of metabolic conversion of LOF to reveal antidepressant activity in this model.

Can the fatal toxicity of antidepressant drugs be predicted with pharmacological and toxicological data?

Antidepressant drugs are among the most common drugs involved in fatal poisoning and large variations between antidepressant drugs have been noted. Despite the fact that a large number of studies have calculated a fatal toxicity index (FTI) for antidepressants, no serious attempts have been made to compare the differences in fatal toxicity against known pharmacological and toxicological differences in receptor affinity. It is potentially from such data that screening of drugs during their pre-clinical development can be facilitated. We examined correlations between the FTI and noradrenaline (norepinephrine)/serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibition selectivity, the dose that is lethal to 50% of animals (LD50), lipid solubility, and antagonist activity at cholinergic, histaminergic, alpha-adrenergic and gamma-aminobutyric acid (GABA)A receptors or sodium and potassium channel blocking effects. We obtained data on the number of fatal poisonings between 1983 and 1992 in England and Wales caused by a single antidepressant drug from the Department of Health in the UK. This number was divided by the number of prescriptions in England for these drugs over this time to derive a FTI of deaths per million prescriptions. The highest FTIs were for amoxapine, viloxazine, desipramine and dothiepin. Lofepramine, paroxetine and fluoxetine had very low FTIs. Using Poisson regression, there was a significant positive relationship between the FTI of antidepressant drugs and their lethal toxicity in animals, and measures of their cardiac effects. The relative noradrenaline/serotonin reuptake inhibition, lipid solubility and their potency at histamine H1, muscarinic and alpha 1-adrenergic receptors had no substantial association with the FTI. Limited data suggest that some cardiac effects and potency as a GABAA antagonist may be important predictors of significant toxicity. Further data using standardised bio-assays are needed to compare the direct cardiac effects of antidepressants. Thus, the best current pre-clinical indicator of fatal toxicity in humans is the LD50 in animal studies. Clearly, there are humane and practical reasons for developing a better pre-clinical indicator of toxicity in overdose for this rapidly expanding group of drugs.

Predictors of response to amine-specific antidepressants

Discriminant function analysis of data from a double-blind comparative trial of lofepramine (a noradrenaline-specific reuptake inhibitor) and fluoxetine (a serotonin-specific reuptake inhibitor), involving 183 patients was used to identify predictors of response. Psychic anxiety significantly predicted a positive response to antidepressant medication, whereas psychomotor retardation, observed sadness, subjective lassitude and somatic complaints were significant predictors of nonresponse. Age, gender, endogenicity, duration of illness and number of previous episodes were not predictive of response. Significant differences were found between predictors of response to fluoxetine and lofepramine (P < 0.001 all groups). Predictors of response to lofepramine were similar to overall predictors, i.e., psychic anxiety predicted responders whilst observed sadness, psychomotor retardation, lassitude, inability to feel and somatic complaints predicted nonresponders. In contrast, baseline weight loss predicted response to fluoxetine, whereas anxiety, reduced insight and a tendency to blame others significantly predicted nonresponse. Such findings have practical implications for the management of depressive illness.

Simultaneous determination of lofepramine and desipramine by a high-performance liquid chromatographic method used for therapeutic drug monitoring

A simple reversed-phase HPLC method with ultraviolet detection for the simultaneous measurement of lofepramine and desipramine is described. Only a single alkaline extraction was used, with clomipramine as internal standard. The column used was a Supelco PCN column, and the mobile phase was acetonitrile-methanol-0.015 M phosphate buffer (120:35:100, v/v). The average recoveries were 78.8% for desipramine and 103.8% for lofepramine, and limits of quantitation were 25 and 5 nmol/l, respectively. The inter-assay C.V.s for lofepramine and desipramine were 6.0 and 7.6%, respectively. The method is specific and has excellent accuracy, and has been used for therapeutic drug monitoring of patients with depressions treated with lofepramine. Mean steady-state plasma concentrations found for lofepramine and desipramine were 8.5 +/- 6.1 and 123.6 +/- 120.6 nmol/l, respectively. It is concluded that lofepramine in itself has an antidepressive effect.

Effect of pharmacologic treatments on the sleep of depressed patients

Antidepressant drugs produce striking effects on sleep architecture that are best understood in terms of their interactions with the monoamine pathways controlling sleep and wakefulness. Many different antidepressant drugs, including tricyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAOIs), and selective 5-hydroxytryptamine (5-HT; serotonin) reuptake inhibitors (SSRIs), decrease rapid eye movement (REM) sleep. The reduction in REM sleep produced by antidepressants may be an important part of their mechanism of action; however, the ability of new antidepressant compounds, such as nefazodone and moclobemide, to increase REM sleep throws doubt on this suggestion. The effects of antidepressants on slow-wave sleep (SWS) are quite diverse; in general, antidepressants having significant 5-HT2A/2C receptor antagonist properties increase SWS, whereas other drugs, such as SSRIs or MAOIs, either lower SWS or produce no change. Sleep continuity is improved acutely following administration of antidepressants with sedating properties such as certain TCAs, trazodone, and mianserin. Some nonsedating drugs (ritanserin and nefazodone) also improve sleep continuity measures, possibly through 5-HT2A/2C receptor blockade.

Pharmacokinetic optimisation of therapy with newer antidepressants

Since the early 1950s, when imipramine was first introduced, a whole series of antidepressants with differences in structures, neurochemical effects and pharmacokinetics have been developed. Structurally or functionally, they have been classified as tricyclic antidepressants (TCAs), tetracyclic antidepressants, monoamine oxidase inhibitors (MAOIs), or selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors (SSRIs). In addition, there is a series of antidepressants with unique structures. Many of the newer TCAs appear to have shorter half-lives than the standard TCAs (e.g. imipramine), allowing for the possibility of a more rapid response, but requiring the drugs to be given in multiple daily doses, which may reduce patient compliance. The short time to peak plasma concentration (tmax) can also lead to rapid onset of adverse effects. The tetracyclic antidepressants have longer elimination half-lives (t1/2) than the TCAs, but there is only very minimal evidence for a relationship between drug concentrations in the blood and clinical response. The triazolopyridines, like the newer TCAs, show pharmacokinetic evidence for rapid onset of adverse effects and the need for multiple daily doses due to short tmax and t1/2. The newer MAOIs are a significant addition to therapy, as the rapid binding action of these medications increases their safety margin with regard to tyramine interactions. Further information in this area is required. In addition, moclobemide has pharmacokinetic features that are clinically beneficial (e.g. aging and renal dysfunction have little effect on the elimination of the drug), but also features that are not beneficial (e.g. nonlinear pharmacokinetics). Among the SSRIs, there are a range of t1/2 values for the parent drugs, from relatively short t1/2 values of less than 24 hours (paroxetine, fluvoxamine) to among the longest found (e.g. 2 days for fluoxetine). Only 2 of the agents (sertraline and citalopram) have linear pharmacokinetics, and 1 drug has nonlinear pharmacokinetics within the usual therapeutic range (fluvoxamine). Once a therapeutic blood concentration is established, linearity is helpful in avoiding the small dose changes and repeated rechecking of concentrations of medications that would be required for those agents with nonlinear pharmacokinetics. Sertraline stands out as having the best effects on behaviour among all antidepressants. However, fluoxetine and fluvoxamine are least likely to penetrate into breast milk. All 3 of the structurally unique newer antidepressants [amfebutamone (bupropion), viloxazine venlafaxine] have relatively short tmax values (1 to 2 hours), which may relate to the early onset of adverse effects. Amfebutamone has the benefits of linear pharmacokinetics with potential for defined therapeutic blood concentrations, lack of effect of liver enzymes on metabolism of the drug, and lack of significant effects of either aging or hepatic dysfunction on elimination of the drug. Thus, the antidepressants best suited for pharmacokinetic optimisation of therapy are the following: desipramine, sertraline, fluvoxamine, citalopram and amfebutamone.

Metabolism of lofepramine and imipramine in liver microsomes from rat and man

1. The in vitro metabolism of lofepramine was studied in comparison with imipramine. Both compounds were hydroxylated and demethylated by a NADPH-generating system in rat and human liver microsomes. 2. Three metabolites were in common for the two drugs, namely desipramine (DMI), 2-hydroxydesipramine (2-OH-DMI) and didesmethylimipramine (DDMI). 3. Lofepramine was also metabolized to three unique tricyclic metabolites. Comparisons with authentic reference compounds suggested that two of these metabolites were 2-hydroxylofepramine and desmethyllofepramine. 4. The ratio between the concentrations of DDMI and DMI was higher for lofepramine than imipramine. This is probably due to DDMI formation via two parallel metabolic pathways of lofepramine, i.e. DMI and desmethyllofepramine, respectively. 5. It is speculated that the different metabolic pattern of lofepramine as compared with desipramine and imipramine is of importance for the therapeutic profile of the drug.

Effect of lofepramine on 5-HT function and sleep

We studied the effect of the tricyclic antidepressant lofepramine (140-210 mg daily for 16 days) on 5-hydroxytryptamine 1A (5-HT1A) receptor sensitivity in healthy volunteers, using a buspirone neuroendocrine challenge paradigm (30 mg orally). We also studied the effect of lofepramine on platelet 5-HT content and sleep architecture. Lofepramine treatment did not alter the hypothermic, endocrine or amnesic effects of buspirone but significantly lowered platelet 5-HT content and decreased rapid eye movement sleep. Our findings suggest that at clinically used doses, lofepramine inhibits the uptake of 5-HT and produces changes in sleep architecture characteristic of tricyclic antidepressants. However, lofepramine does not appear to alter the sensitivity of 5-HT1A receptors.

Effects of lofepramine and dothiepin on memory and psychomotor function in healthy volunteers

The effects of single doses of lofepramine (70 mg), dothiepin (50 mg) and placebo on memory and psychomotor function were compared in a cross-over study with 12 healthy volunteers. Dothiepin produced a differential pattern of effects across the range of memory assessments used, impairing episodic memory and slowing learning in a procedural task but not affecting working, semantic or implicit memory. Dothiepin also impaired performance on two attentional tasks, slowed down reaction times and increased subjective sedation. Lofepramine was similar to placebo on nearly all objective measures, but produced effects similar to dothiepin on critical flicker fusion threshold, salivary flow and most EEG wavebands. It is concluded that, unlike lofepramine, acute dosage with dothiepin is associated with sedative effects and impairments of concentration and memory.

Clinical and biochemical aspects of depressive disorders: III. Treatment and controversies

The present document is the final of three parts of a review that focuses on recent data from clinical and animal research concerning the biochemical bases of depressive disorders, diagnosis, and treatment. Various treatments for depression, including psychotherapy, pharmacological, and somatic treatments, will be described in this third part. Also, some of the controversies in the field, as well as a summary of the most salient points of the review, will be discussed. Previous sections of this review dealt with the classification of depressive disorders and research techniques for studying the biochemical mechanisms of these disorders (Part I) and various transmitter/receptor theories of depressive disorder (Part II).

Drug treatment of depression in medically ill patients

Depressive symptoms are common in medically ill patients although depressive disorders are considerably underdiagnosed and undertreated. Drug treatments for depression are reviewed in terms of a risk/benefit analysis. The main benefit is approximately to double the chance of recovery (from about 30 to 65%), with possible associated improvements in physical condition. The risks of treatment are considerable and include overdose, unwanted effects at therapeutic dose and interaction with other drugs. Among the risks associated with specific medical conditions are orthostatic hypotension, cardiotoxicity, deterioration of seizure control in epileptic patients and increased side effects in patients with renal and hepatic impairment. The available data suggest that there is relatively little to choose between antidepressants in terms of efficacy (although the quantity and quality of these data vary). It is therefore primarily the risks which should determine the choice of antidepressant, and these must be separately evaluated for each patient.

Idiosyncratic reactions to antidepressants: a review of the possible mechanisms and predisposing factors

Antidepressants, a widely used group of drugs, are associated with a range of idiosyncratic reactions affecting in particular the liver, skin and both the hematological and central nervous systems. These reactions seem to be mediated by chemically reactive metabolites formed by the cytochrome P450 enzyme system, the toxicity occurring either directly or indirectly via an immune mechanism. Individual susceptibility is determined by factors, both genetic and environmental, which result in inadequate detoxication of the chemically reactive metabolite. Prevention of such reactions will depend on either the development of new compounds which are not converted to toxic metabolites or by prediction of individual susceptibility prior to drug administration.

The effects of lofepramine and desmethylimipramine on tryptophan metabolism and disposition in the rat

Acute and chronic administration of lofepramine and its major metabolite desmethylimipramine (DMI) to rats elevates brain tryptophan concentration, thereby enhancing cerebral 5-hydroxytryptamine (5-HT) synthesis, by increasing the availability of circulating tryptophan to the brain, secondarily to inhibition of liver tryptophan pyrrolase (tryptophan 2,3-dioxygenase, L-tryptophan:O2 oxidoreductase, decyclizing; EC 1.13.11.11) activity. The pyrrolase inhibition by lofepramine occurs independently of metabolism to DMI, because it can be demonstrated directly in vitro. Lofepramine also differs from DMI in its action profile on the above and related aspects of tryptophan metabolism and disposition. These results demonstrate that lofepramine influences tryptophan and 5-HT metabolism and disposition independently of its major metabolite DMI, and are discussed briefly in relation to the mechanism of action of antidepressants.

Effects of (S)-nafenodone, a new antidepressant, in isolated guinea-pig atrial and ventricular muscle fibres

The electromechanical effects of a new antidepressant, (S)-nafenodone, were studied in isolated guinea-pig atrial and ventricular muscle fibres. In spontaneously beating right atria, (S)-nafenodone decreased the rate and amplitude of contractions and lengthened the sinus node recovery time. In electrically driven atria, the negative inotropic effect of (S)-nafenodone was less marked than that of imipramine and desipramine but similar to that of lofepramine. (S)-Nafenodone had no effect on the resting membrane potential but decreased the amplitude and maximum upstroke velocity (Vmax) both in atrial and ventricular muscle fibres; this effect was less marked than that produced by imipramine and desipramine. In atrial fibres, but not in ventricular fibres, (S)-nafenodone lengthened the action potential duration, but in both tissues it increased the duration of the effective refractory period out of proportion to the change in action potential duration. Moreover, it shifted the concentration-response curve for Ca2+ downwards and decreased the amplitude of the slow atrial contractions induced by histamine as well as the amplitude and Vmax of the slow action potentials induced by isoprenaline in papillary muscles. It is concluded that (S)-nafenodone exerted fewer cardiodepressant effects than imipramine and desipramine in isolated guinea-pig atrial and ventricular muscle fibres less.

Meta-analyses of the efficacy and tolerability of the tricyclic antidepressant lofepramine

Lofepramine is a tricyclic antidepressant related to imipramine. Meta-analyses were carried out with respect to efficacy and tolerability by combining outcome and adverse reaction from over 20 controlled trials comparing lofepramine with other tricyclic antidepressants. Lofepramine was at least as effective as the comparators with fewer adverse effects. In particular, the risk/benefit ratio seemed superior to the comparators amitriptyline, imipramine, clomipramine, maprotiline and desipramine.