Treatment of the serotonin syndrome with cyproheptadine

The serotonin syndrome is the result of excess stimulation of central nervous 5-hydroxytryptamine (5HT)-1a and 5HT-2 receptors. The diagnosis requires a history of exposure to agents active at serotonin receptors and the presence of alterations in mental status, autonomic instability, and neuromuscular abnormalities such as tremor, hyperreflexia, or myoclonus. In this descriptive case series, five cases of serotonin syndrome are reported. All patients gave a history of recent exposure to one or more serotonergic medications, including moclobemide, paroxetine, sertraline, and venlafaxine, with clinical evidence of serotonin syndrome. All patients were administered cyproheptadine (4-8 mg orally) for serotonergic signs. Three had complete resolution of signs within 2 h of administration. Another two had a residual tremor or hyperreflexia following the first dose, which resolved following a repeat dose. There were no adverse outcomes from cyproheptadine use. The role of specific serotonin receptor antagonists such as cyproheptadine in the treatment of the serotonin syndrome remains to be delineated. Its use should be considered an adjunct to supportive care. Currently, it is unknown whether cyproheptadine modifies patient outcome.

Pharmacotherapy of social phobia. A controlled study with moclobemide and phenelzine

In a double-blind, parallel group trial, 78 subjects with social phobia received moclobemide (a new reversible inhibitor of monoamine oxidase A) phenelzine, or placebo. After eight weeks, both active drugs-phenelzine somewhat more than moclobemide--were clinically and statistically significantly more effective than placebo, as assessed by rating scales. There was some further improvement between weeks 8 and 16, particularly in the moclobemide group; at week 16, 82% of the moclobemide and 91% of the phenelzine-treated patients were almost asymptomatic. Moclobemide was, however, much better tolerated than phenelzine. Patients withdrawn from active drugs had relapsed by week 24, providing additional support for the efficacy of the active drugs.

Hypothalamic-pituitary-adrenocortical axis changes in the rat after long-term treatment with the reversible monoamine oxidase-A inhibitor moclobemide

The effects of the reversible monoamine oxidaseA (MAOA) inhibitor moclobemide on the rat hypothalamic-pituitary-adrenocortical (HPA) axis were studied. The time-course experiments showed that moclobemide, given via the drinking water (4.5 mg/kg/day), produces significant decreases (p < 0.05) in adrenal weight after 5 (-23%) and 7 weeks (-16%) of treatment. It was found that long-term moclobemide treatment had neuroanatomically distinct effects on corticosteroid receptor expression. Hippocampal mineralocorticoid receptor (MR) levels were upregulated at 2 (+65%), 5 (+76%) and 7 (+19%) weeks of treatment. Glucocorticoid receptor (GR) levels in this limbic brain structure were slightly up-regulated by 10% at 5 weeks, and indistinguishable from controls after 2 and 7 weeks of treatment. After 5 weeks of treatment, MR levels were unchanged in the hypothalamus, and increased by 44, 24 and 28% in the neocortex, amygdala and anterior pituitary, respectively. GR concentrations were elevated by 24 and 14% in the hypothalamus and anterior pituitary, respectively, whereas neocortical and amygdaloid receptor levels were not altered. After 5 weeks of moclobemide treatment, marked decreases in [125I]Tyr0-ovine corticotropin-releasing hormone ([125I])-oCRH binding capacity and proopiomelanocortin (POMC) mRNA content were observed in the anterior pituitary. Regarding the functional implications of long-term anti-depressant treatment, moclobemide treatment (5 weeks, 4.5 mg/kg/day) significantly attenuated stress (30-min novel environment)-induced plasma ACTH (-35%) and corticosterone (-29%) levels; no changes were observed in basal plasma ACTH and corticosterone levels. In conclusion, this study shows that moclobemide has a concerted influence on multiple elements of the HPA axis manifesting functionally as a reduced neuroendocrine responsiveness to stress. In previous experiments, it was found that the structurally and pharmacologically distinct antidepressant amitriptyline after long-term administration also attenuated HPA axis activity. We postulate that an adjustement of HPA axis activity may be regarded as a common denominator for clinically efficacious antidepressant drugs.

Long-term antidepressant treatment reduces behavioural deficits in transgenic mice with impaired glucocorticoid receptor function

Impaired cognitive function and enhanced activity of the hypothalamic-pituitary-adrenocortical system are among the cardinal symptoms of major depression in humans that resolve after successful antidepressant treatment. We used a transgenic mouse model expressing antisense RNA complementary to that of glucocorticoid receptor (GR) mRNA to test the hypothesis that reduced GR function can cause these clinical disturbances. The transgenic mice show profound behavioural changes in a number of animal tests that are indicative of cognitive impairment. These mice also have elevated plasma corticotropin concentrations in response to stress. After long-term treatment with moclobemide, a reversible inhibitor of monoamine oxidase type A that acts clinically as an antidepressant, both the behavioural deficits and the hormonal alterations disappeared. These observations suggest that a transgenic mouse with GR dysfunction may be a useful model for investigation of drug effects on the cognitive and neuroendocrine aspects of depression.

Meta-analysis of the reversible inhibitors of monoamine oxidase type A moclobemide and brofaromine for the treatment of depression

The reversible inhibitors of monoamine oxidase type A (RIMAs) are a newer group of antidepressants that have had much less impact on clinical psychopharmacology than another contemporary class of medications, the selective serotonin reuptake-inhibitors (SSRIs). The RIMAs agents are distinguished from the older monoamine oxidase inhibitors (MAOIs) by their selectivity and reversibility. As a result, dietary restrictions are not required during RIMA therapy, and hypertensive crises are quite rare. In this article, we describe a series of meta-analyses of studies of the two most widely researched RIMAs, moclobemide (MOC; Aurorex) and brofaromine (BRO). Our findings confirm that both BRO and MOC are as effective as the tricyclic antidepressants, and they are better tolerated. However, BRO is not being studied at present for reasons unrelated to efficacy or side effects. MOC, which is available throughout much of the world (but not the United States), is significantly more effective than placebo and, at the least, comparable to the SSRIs in both efficacy and tolerability. For MOC, higher dosages may enhance efficacy for more severe depressions. We also found evidence that supports clinical impressions that MOC is somewhat less effective, albeit better tolerated, than older MAOIs, such as phenelzine or tranylcypromine. Little evidence has yet emerged to suggest that the RIMAs share older MAOIs' utility for treatment of depressions characterized by prominent reverse neurovegetative features. Based on available evidence, the RIMAs appear to have a limited, but useful, role in the differential therapeutics of the depressive disorders.

Moclobemide in elderly patients with cognitive decline and depression: an international double-blind, placebo-controlled trial

BACKGROUND

The new reversible MAOl moclobemide was compared with placebo in the treatment of elderly patients with DSM-III diagnosis of dementia and/or of major depression.

METHOD

Six hundred and ninety-four elderly patients with symptoms of depression and cognitive decline entered an international, multi-centre, double blind trial in which they were randomly allocated to treatment with either moclobemide 400 mg daily or placebo for 42 days. Five hundred and eleven patients met DSM-III criteria for dementia and were also depressed (DEM+D); 183 did not meet DSM-III criteria for dementia but met the criteria for DSM-III major depressive episode and also suffered from cognitive decline (MDE+CD).

RESULTS

Analysis of the 17 and 24-item Hamilton Depression Scale scores showed that moclobemide, compared with placebo, produced significantly greater improvement in both the demented and depressed groups (P = 0.001 both diagnostic groups). There was an improvement in cognitive function as measured by the SCAG Factor 1 in moclobemide treated patients (P = 0.005 DEM+D; P = 0.02 MDE+CD). There was no evidence of decline in cognitive function as the result of treatment. Clinical global assessment of tolerance was 'excellent' and 'good' in 88% of the moclobemide and in 92% of the placebo treated patients. The proportion of patients discontinuing treatment prematurely was similar in both treatment groups. There were no significant differences in side-effects between treatment groups. There were no significant changes in vital signs, ECG or laboratory findings in either treatment group. There were no dietary restrictions and no report of any tyramine reaction.

CONCLUSIONS

Moclobemide was shown to be a safe, well tolerated and effective antidepressant, which did not cause impairment of cognitive function in elderly patients with a DSM-III diagnosis of dementia and/or DSM-III major depression.

A reversible monoamine oxidase A inhibitor (moclobemide) facilitates smoking cessation and abstinence in heavy, dependent smokers

OBJECTIVE

To assess the effectiveness of moclobemide on smoking cessation and abstinence in heavy, dependent smokers. There is a strong association between smoking and depression, especially in dependent smokers. It was hypothesized that smoking is a self-medication to treat depression. Cigarette smoke has monoamine oxidase (MAO)-inhibitory properties, and smokers have lower MAO activity than non-smokers.

METHODS

We used a randomized, double-blind, placebo-controlled parallel-group study. Placebo or moclobemide, 400 mg/day for 2 months and 200 mg/day during the third month, was given. Main outcome measures were self-reported and biochemically verified (plasma cotinine levels, < 20 ng/ml) abstinence rate. Secondary outcome measures were withdrawal symptoms, Montgomery-Asberg Depression Rating Scale, Hamilton anxiety rating scores, platelet MAO-B activity, and plasma dihydroxyphenylglycol as a measure of MAO-A activity.

RESULTS

Eighty-eight smokers were randomized to receive moclobemide (n = 44) or placebo (n = 44). The continuous self-reported abstinence rate was higher with moclobemide than with placebo (intention-to-treat analysis until the end point, 6 months: p < 0.05; until the end of follow-up, 1 year: p = 0.09). The abstinence rate according to plasma cotinine levels showed a trend to effectiveness of moclobemide (end point: p = 0.13; follow-up: p = 0.12). Platelet MAO-B activity increased after smoking cessation but without a significant difference. Plasma dihydroxyphenylglycol levels did not change in the placebo group but decreased dose dependently in the moclobemide group. No difference occurred for withdrawal symptoms, Montgomery-Asberg Depression Rating Scale, and Hamilton anxiety scores. Cessation of moclobemide had no adverse effect. More subjects reported insomnia with moclobemide (n = 16) than with placebo (n = 3).

CONCLUSION

In this preliminary study, the reversible, selective MAO inhibitor moclobemide facilitated smoking cessation in highly dependent smokers. Further studies with substantially more smokers are needed to evaluate the role of MAO inhibitors in smoking cessation and abstinence in smokers with high nicotine dependence.

Moclobemide in social phobia: a controlled dose-response trial

Although the monoamine oxidase inhibitor phenelzine has proven efficacious in social phobia, the risk of hypertensive crises has reduced its acceptability. The reversible monoamine oxidase inhibitor moclobemide has less potential for such reactions, but its efficacy in this disorder remains unproven. A double-blind, placebo-controlled study was undertaken to assess the efficacy and safety of fixed doses of moclobemide. After a 1-week placebo run-in, subjects with social phobia were randomly assigned to placebo or one of five doses (75 mg, 150 mg, 300 mg, 600 mg, or 900 mg daily) of moclobemide for 12 weeks. Although a trend toward greater efficacy of higher doses of moclobemide was observed at 8 weeks, no differences in response to various doses of the drug and placebo were observed at 12 weeks. At 12 weeks, 35% of subjects on 900 mg of moclobemide and 33% of those on placebo were at least much improved. Moclobemide was well tolerated, insomnia being the only dose-related adverse event observed with the drug. In this dose-response trial, moclobemide did not demonstrate efficacy at 12 weeks. Some other controlled studies have found moclobemide and brofaromine, another reversible monoamine oxidase inhibitor, efficacious in social phobia. Possible reasons for inconsistent findings are discussed.

A randomized, double-blind, placebo-controlled study of moclobemide and amitriptyline in the treatment of fibromyalgia in females without psychiatric disorder

OBJECTIVE

To study the usefulness of moclobemide and amitriptyline in the treatment of fibromyalgia (FM) in females without psychiatric disorder.

METHODS

In the present four centre, 12 week study, 130 female FM patients not suffering from psychiatric disorders were randomized to receive amitriptyline (AMI; 25 37.5 mg), moclobemide (MOCLO; 450-600 mg) or identical placebo.

RESULTS

Seventy-four, 54 and 49 per cent of patients on AMI, MOCLO and placebo, respectively, were judged as responders. The patients on AMI also managed best regarding the respective improvements during the trial in general health, pain, sleep quality and quantity, and fatigue on visual analogue scales (VAS), the areas of the Nottingham Health Profile (NHP), as well as in the three Sheehan's functional disability scales. In the within-group comparisons, MOCLO also improved pain assessed both on VAS and on the NHP pain dimension, but the improvement was invalidated by the poor success of the drug with regard to sleep. The tolerabilities of all three drugs were comparable.

CONCLUSION

The study indicates that MOCLO may not be helpful in FM patients free from clinically meaningful psychiatric problems.

Placebo-controlled trial of moclobemide in social phobia

BACKGROUND

Moclobemide, a reversible inhibitor of monoamine oxidase A, previously has been reported to have efficacy in the treatment of social phobia.

METHOD

Seventy-seven non-responders to one week of single-blind placebo were randomly assigned to moclobemide or placebo for eight weeks of double-blind treatment. Outcome was assessed by independent evaluator, treating psychiatrist and self-ratings. After eight weeks, patients who were at least minimally improved continued treatment for a further eight weeks.

RESULTS

Intention-to-treat sample response rates at week 8 were 7/40 (17.5%) for the moclobemide group and 5/37 (13.5%) for placebo (NS). Moclobemide was significantly superior to placebo on 2 of 10 primary outcome measures. Moclobemide was well tolerated.

CONCLUSIONS

Moclobemide may have efficacy in the treatment of social phobia, but absence of significant differences on most primary outcome measures and small effect sizes for all outcome measures suggest that the magnitude of its clinical effect is small.

Moclobemide: a reversible MAO-A-inhibitor showing weaker antidepressant effect than clomipramine in a controlled multicenter study. Danish University Antidepressant Group

Antidepressant and unwanted effects of moclobemide (400 mg/day) and clomipramine (150 mg/day) were compared in a double-blind, randomised, in-patient, fixed-dose study with weekly ratings and drug level measurements. After 1 week of single-blind placebo treatment, 115 patients with major depression fulfilled the criterion of a Hamilton Depression Scale (17-item, HDS) score of > or = 18 and were started on active treatment for 6 weeks. Drop-outs on moclobemide (n = 20) were in particular due to worsening and suicidality (n = 9) whereas drop-outs on clomipramine (n = 12) in particular were due to side effects/adverse events (n = 6) and no drop-outs due to worsening. End-point analysis on the basis of different depression ratings showed consistently a significantly weaker effect of moclobemide (final median HDS: 15) compared with clomipramine (final median HDS: 11). The difference involved both sleep and depression symptoms. These results are generally at variance with the main body of literature on moclobemide, although a higher frequency of drop-out due to worsening in moclobemide-treated patients compared to tricyclic antidepressant-treated patients has been reported in several studies.

Moclobemide, a substrate of CYP2C19 and an inhibitor of CYP2C19, CYP2D6, and CYP1A2: a panel study

The reversible monoamine oxidase A inhibitor moclobemide was given in single (300 mg) and multiple doses (600 mg/day) to 11 male and four female healthy volunteers (age range, 23 to 27) who were either poor metabolizers of S-mephenytoin (n = 7) or extensive metabolizers of S-mephenytoin (n = 8). All were extensive metabolizers of sparteine. Poor metabolizers of S-mephenytoin had lower moclobemide clearance values (median, single dose: 16.1 versus 43.2 L.hr-1; steady state: 13.4 versus 22.1 L.hr-1) and longer moclobemide half-life values (median, single dose: 4.0 versus 1.8 hours; steady state: 5.1 versus 2.7 hours) than extensive metabolizers of S-mephenytoin. The plasma levels of a metabolite formed by C-hydroxylation (Ro 12-8095) were lower in poor metabolizers of S-mephenytoin than in extensive metabolizers of S-mephenytoin. Moclobemide thus partially undergoes oxidative metabolism by way of the polymorphic CYP2C19. A combined mephenytoin, sparteine, and caffeine test performed before, during, and after multiple dosing of moclobemide showed changes in the metabolic indexes compatible with a reversible inhibition of oxidation by way of the corresponding CYP enzymes--CYP2C19, CYP2D6, and CYP1A2--during moclobemide treatment.

Biochemistry and pharmacology of moclobemide, a prototype RIMA

RIMA is a term for reversible inhibitors of monoamine oxidase (MAO) with preference for MAO-A; moclobemide is a prototype of this new class of antidepressants and is a highly selective inhibitor of MAO-A in vitro. This inhibition is reversible by dialysis in vitro, which accounts for the dose-dependent duration of in vivo enzyme inhibition of 12-24 h. Moclobemide increases the content of serotonin, noradrenaline and dopamine in the brain, and decreases that of their deaminated metabolites. Its biochemical, neurological and behavioural effects indicate that it increases the extracellular concentration of the classic monoamine neurotransmitters/neuromodulators - in particular 5-HT. Potentiation of the cardiovascular effects of tyramine is less pronounced after taking moclobemide than after irreversible MAO-A inhibitors. Understanding of the physiological role of MAO and of the events that link inhibition of the enzyme with modulation of neuronal activities in the CNS remains incomplete. A major physiological role of intraneuronal MAO is to keep cytosolic amine concentration very low, to enable the neuronal monoamine carriers to produce a net inward transport of monoamines, and thereby to act as the first step in the termination of action of extracellular monoamines. MAO is likely to have a similar function in non-monoaminergic cells with respect to the monoamine carriers they contain. In addition to the classic monoamines, "trace" amines may become functionally active after MAO inhibition. An alternative role for MAO is that of a scavenger, preventing natural substrates from accumulating in monoaminergic neurons and interacting with storage, release, uptake and receptor function of monoamines.

Brofaromine for social phobia: a multicenter, placebo-controlled, double-blind study

The safety and efficacy of brofaromine, a reversible and selective monoamine oxidase inhibitor, were examined in a multicenter trial of 102 outpatients with social phobia. After a 1-week placebo washout, subjects were randomly assigned to 10 weeks of treatment with either brofaromine (N = 52) or placebo (N = 50). Brofaromine dosage began at 50 mg/day and was titrated to a maximum of 150 mg/day, depending on treatment response. Brofaromine produced a significantly greater change from baseline in Liebowitz Social Anxiety Scale (LSAS) scores compared with placebo, F(1) = 6.01, p < 0.016. Mean LSAS scores decreased from 81.8 at baseline to 62.6 at endpoint for brofaromine, t = 5.41,p < 0.001, and from 79.8 to 70.7 for placebo, t = 3.66, p < 0.001. Eleven of the 14 brofaromine early terminators discontinued because of adverse experiences, as did 4 of the 17 placebo early terminators. Side effects more common with brofaromine than placebo included insomnia, dizziness, dry mouth, anorexia, tinnitus, and tremor. No clinically significant variations in vital signs or laboratory values were found. The findings are consistent with the clinical efficacy for the treatment of social phobia.

Moclobemide. A review of its pharmacological properties and therapeutic use in depressive illness

Moclobemide is a reversible and selective inhibitor of the enzyme monoamine oxidase (MAO) subtype A with a broad spectrum of antidepressant activity. Controlled clinical studies suggest that the short term clinical efficacy of moclobemide is significantly superior to that of placebo, and comparable to that of the tricyclic antidepressants clomipramine, amitriptyline, imipramine and desipramine, the irreversible MAO inhibitor tranylcypromine and the second-generation antidepressants maprotiline, mianserin and fluvoxamine in the treatment of major depressive illness. Moclobemide appears to be equally effective in endogenous and nonendogenous depression, producing marked amelioration of clinical features of psychomotor retardation and depressed mood. Moclobemide is well tolerated, being largely devoid of the anticholinergic adverse effects, symptomatic postural hypotension and weight gain variously associated with the tricyclic antidepressants and irreversible MAO inhibitors, and appears considerably safer on overdosage than the tricyclic and second generation antidepressants. Moreover, moclobemide offers the advantage over the older, irreversible MAO inhibitors of causing only minimal potentiation of the pressor response to dietary tyramine (the so-called 'cheese effect'). Consequently, the risk of potentially fatal hypertensive crisis, a major deterrent to the wider acceptance of these earlier compounds, is substantially reduced with moclobemide, and the need for dietary precautions is minimised. With its efficacy against endogenous and nonendogenous depression, relatively rapid onset of antidepressant activity, and absence of carry-over effects on treatment withdrawal, moclobemide is likely to make an important contribution to the treatment of major depressive illness. Its favourable tolerability profile, safety on overdosage and beneficial effect on age-related cognitive impairment may be of particular value in the elderly and those with concurrent physical illness.

Plasma 3,4-dihydroxyphenylglycol (DHPG) and 3-methoxy-4-hydroxyphenylglycol (MHPG) are insensitive indicators of alpha 2-adrenoceptor mediated regulation of norepinephrine release in healthy human volunteers

The usefulness of the plasma concentrations of two major metabolites of norepinephrine (NE), 3,4-dihydroxyphenylglycol (DHPG) and 3-methoxy-4-hydroxyphenylglycol (MHPG), as indicators of neuronal NE release was investigated. The potent alpha 2-adrenoceptor agonist, dexmedetomidine, induced only about 15% maximal reductions in the metabolite concentrations, in spite of almost total inhibition of neuronal NE release, as evidenced by 90% reductions in plasma NE concentrations. Similarly, administration of the alpha 2-adrenoceptor antagonist atipamezole was followed by only small increases in plasma DHPG and no change in MHPG levels, in spite of almost six-fold, albeit short-lasting, increases in plasma NE. In contrast, a single dose of the reversible monoamine oxidase type A (MAO-A) inhibitor moclobemide reduced plasma DHPG levels by 78% and MHPG levels by 51%. It is concluded that the plasma concentrations of DHPG and MHPG are largely determined by intraneuronal, MAO-A-dependent metabolism of NE, and do not accurately reflect acute alterations in neuronal NE release. The concentration of NE in venous plasma is clearly a more sensitive indicator of alpha 2-adrenoceptor-mediated regulation of NE release.

Short-acting novel MAO inhibitors: in vitro evidence for the reversibility of MAO inhibition by moclobemide and Ro 16-6491

The inhibition of monoamine oxidase (MAO) in rat liver and brain by the short-acting MAO-A inhibitors moclobemide (Ro 11-1163 = p-chloro-N-[2-morpholinoethyl]benzamide) and brofaremine and by the short-acting MAO-B inhibitors Ro 16-6491 (N-[2-aminoethyl]-p-chloro-benzamide) and almoxatone, administered p.o. at roughly equieffective doses 2 h before decapitation, was investigated for its reversibility under various in vitro conditions. MAO A activity in liver homogenates, inhibited by moclobemide (300 mumol/kg) to approx. 15% of control, time dependently recovered during 0.5 to 2 h of incubation at 37 degrees C, irrespective of whether the homogenates were prepared and incubated in distilled water or Krebs-Ringer buffer (KRB). Dialysis of such homogenates for 4 h in distilled water at 37 degrees C (but not at 13 degrees C) led to a complete return of the MAO activity. In liver homogenates from rats pretreated with brofaremine (30 mumol/kg), dialysis for 4 h at 37 degrees C against distilled water caused only little recovery of the MAO activity. Likewise, MAO-B inhibited by Ro 16-6491 (30 mumol/kg) to approx. 4% of control returned to almost control activity after 4 h of dialysis at 37 degrees C, while inhibition induced by almoxatone (30 mumol/kg) was little or not reversed at all. In brain homogenates prepared in, and dialysed against, distilled water or KRB at 37 degrees C (but not at 13 degrees C), MAO-A inhibited by moclobemide (100-300 mumol/kg) to approx. 15% of control, partially (KRB) or almost completely (dist. water) returned to control activity after 4 h of dialysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug interactions of clinical significance with selective serotonin reuptake inhibitors

The selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors (SSRIs) have internationally become the accepted 'benchmark' class of antidepressants. It has become clear, however, that there are a number of clinically significant interactions between SSRIs and other medications. The most frequently described interactions are pharmacokinetic, which are far more prevalent than pharmacodynamic interactions. This article details those medications that may interact significantly with the SSRIs, and provides clinical guidelines for minimising the likelihood of such complications. The most common pharmacokinetic interactions are caused by an inhibitory effect of the SSRIs on the hepatic cytochrome P450 (CYP) metabolic system. The SSRIs differ in their potency in inhibiting a number of important CYP isoenzymes (CYP1A2, CYP2C9/10, CYP2C19, CYP2D6 and CYP3A3/4). The major outcome of concern in relation to pharmacodynamic interactions is the development of the 'serotonin syndrome'. While combination of the SSRIs with the irreversible monoamine oxidase inhibitors is the most recognised cause of this syndrome, concurrent administration with moclobemide, tryptophan or selegiline (deprenyl) may also lead to a similar outcome.

Moclobemide. An update of its pharmacological properties and therapeutic use

Unlike older monoamine oxidase inhibitors, which irreversibly and nonselectively bind monoamine oxidase (MAO), moclobemide is a reversible and selective inhibitor of the MAO-A isozyme. Moclobemide only weakly potentiates the pressor response induced by tyramine or other indirectly acting sympathomimetics; therefore, there is no need to avoid dietary tyramine or over-the-counter decongestants with moclobemide as there is with older MAO inhibitors. Recent clinical trials and meta-analyses have confirmed the efficacy of moclobemide in the treatment of depressive disorders. Moclobemide has been shown to have similar efficacy to tricyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs) and nonselective, irreversible MAO inhibitors. Long term follow-up studies of 6 to 12 months' duration have demonstrated that the antidepressant efficacy of moclobemide is maintained. Moclobemide, given alone or in combination with another antidepressant, has shown some efficacy in patients with refractory depression; however, comparative trials are required to confirm these findings. Data are also available to show clinical efficacy of moclobemide in the management of social phobia. Comparative studies have established that moclobemide is better tolerated at therapeutic dosages and has less toxicity in overdose than TCAs and nonselective, irreversible MAO inhibitors. Moclobemide lacks the anticholinergic, sedative and cardiovascular effects associated with many of the older antidepressants. Compared with SSRIs, moclobemide has a similar overall tolerability, although it tends to cause fewer gastrointestinal effects than the SSRIs and has not been reported to interfere with sexual function. In summary, recent data which confirm and extend its comparative therapeutic efficacy and low potential for adverse effects have established moclobemide as an effective treatment in depressive disorders. The drug is also effective in patients with a primary diagnosis of social phobia. Its lack of adverse anticholinergic, cardiovascular, cognitive and psychomotor effects makes moclobemide a particularly useful option in the elderly or patients with cardiac disease.

Moclobemide and fluoxetine in atypical depression: a double-blind trial

The effectiveness of moclobemide or fluoxetine in the treatment of atypical (n = 53) and other depressive patients (n = 156) was compared in a 6-week double-blind randomized trial. HDRS, MARDS, GCI and the Atypical Depression Diagnostic Scale were used in clinical assessment. Significant differences were seen in MADRS and GCI scores in favour of moclobemide in the treatment of atypical depression, but not with HDRS. No major differences were seen between the two drugs in the treatment of other depressive patients. A positive response, defined by a > 50% decrease in HDRS score and a GCI Improvement Score of 1 or 2, was seen among 67% of atypical patients treated with moclobemide and among 55% treated with fluoxetine and in 60 and 48% of other depressive patients, respectively. Both drugs gave results with atypical patients at least as good as with other depressive patients. Our results suggest that patients suffering from atypical depression may respond more favourably to moclobemide than to fluoxetine treatment.

Comparison of the monoamine oxidase inhibiting properties of two reversible and selective monoamine oxidase-A inhibitors moclobemide and toloxatone, and assessment of their effect on psychometric performance in healthy subjects

1. The effects of two reversible, predominantly monoamine oxidase-A (MAO-A) inhibitors, moclobemide (150 mg three times daily) and toloxatone (400-200-400 mg day-1) on monoamine metabolites and psychometric performance were compared in a double-blind placebo controlled crossover study in 12 healthy subjects. 2. After 7 days of moclobemide/toloxatone/placebo administration subjects were hospitalized for 24 h on day 8. Blood samples were drawn every 2 h for determination of plasma noradrenaline (NA), 3,4-dihydroxyphenylglycol (DHPG), homovanillic acid (HVA) and 5-hydroxyindolacetic acid (5-HIAA). Urine was collected for measurements of normetanephrine and 3-methoxytyramine excretion. Psychometric performance (short- and long-term memory, critical flicker fusion frequency, choice reaction time) and subjective feelings were assessed before each drug intake (in the morning, at noon, in the evening). 3. Compared with placebo, both reversible monoamine oxidase inhibitors decreased the plasma concentration of DHPG and HVA. The overall fall in DHPG (AUC from 0 to 24 h) was 44% during moclobemide and 12% during toloxatone (P less than 0.001) and the overall decrease in HVA was 38% and 20% (P less than 0.005) on moclobemide and toloxatone, respectively. 4. Before the next drug intake, MAO-A inhibition, as judged by the decrease of plasma DHPG concentration, was significantly different from placebo with moclobemide but not with toloxatone. 5. Moclobemide, but not toloxatone, exerted a moderate, but significant inhibition of the deamination of 5-hydroxytryptamine (5-HT) as judged by the fall in plasma 5-HIAA concentration. Neither drug influenced plasma NA concentration. 6. A significant rise in urinary excretion of normetanephrine was observed on moclobemide and to a lesser extent on toloxatone. The urinary excretion of 3-methoxytyramine was significantly raised by moclobemide but not by toloxatone. 7. Neither moclobemide nor toloxatone altered memory function, vigilance, subjective feelings or sleep characteristics of the subjects.

Efficacy of moclobemide in different patient groups: a meta-analysis of studies

Whilst tricyclic antidepressants are efficacious in all depressive syndromes, classical MAO-inhibitors differ substantially from them in their action. They are considered less effective in general and not very effective in endogenous depression, but recommended for the treatment of 'atypical' depression. A new class of RIMA (Reversible Inhibitors of MAO-A) represented by moclobemide requires a change in clinical thinking on antidepressants. Moclobemide shows the same efficacy in depression as tricyclics: its effects are similar in unipolar and bipolar affective disorders, and in patients with major depressive episode superimposed on dysthymia (double depression). As with classical antidepressants, the response rate tends to be lower, but is still present in psychotic depression. Agitated depressives do not respond less well than non-agitated patients to moclobemide. Patients meeting DSM-III-R criteria for major depression with melancholia tend to respond better than non-melancholics, but this may be associated with the significantly higher baseline severity observed in melancholics. A slightly higher response rate in patients without concomitant benzodiazepine treatment, compared to those with benzodiazepine comedication, may also be related to baseline differences in the severity of depression. Elderly depressives respond less well than younger patients to classical antidepressants, but with moclobemide, elderly patients do as well as younger ones.

Inhibition of monoamine oxidase by moclobemide: effects on monoamine metabolism and secretion of anterior pituitary hormones and cortisol in healthy volunteers

1. Single oral doses (100, 200 and 300 mg) of moclobemide, a reversible inhibitor of monoamine oxidase (MAO) with predominant effects on the A-type of the enzyme, were administered to eight young, healthy male volunteers in a double-blind, random-order, placebo-controlled study. The investigation was thereafter continued in an open fashion by administering a single 10 mg dose of the MAO-B inhibitor deprenyl to the same subjects. 2. Deamination of catecholamines was powerfully and dose-dependently inhibited by moclobemide, as evidenced by up to 40% decreases in the urinary excretion of deaminated catecholamine metabolites, corresponding increases in the excretion of non-deaminated, methylated metabolites, and up to 79% average decreases in the plasma concentration of 3,4-dihydroxyphenylglycol (DHPG), a deaminated metabolite of noradrenaline (NA), and up to 75% average decreases in the plasma concentrations of 3,4-dihydroxyphenylacetic acid (DOPAC), a deaminated metabolite of dopamine. The urinary excretion of 5-hydroxyindoleacetic acid (5-HIAA) was only slightly reduced. In contrast, deprenyl, in a dose which almost totally inhibited MAO-B activity in blood platelets, did not appreciably affect the plasma concentrations of DHPG or DOPAC. 3. Due to the rapid, reversible, dose-dependent and MAO-A specific effect of moclobemide on plasma concentrations of DHPG, it is suggested that DHPG in plasma may be a useful indicator of the magnitude and duration of MAO-A inhibition in man. 4. Sympatho-adrenal function at rest was not significantly altered by moclobemide, as judged by unchanged plasma catecholamine concentrations and stable blood pressure and heart rate recordings. 5. Monoamine oxidase type B activity in blood platelets was slightly (less than 30%) and transiently inhibited after moclobemide. 6. The secretion of prolactin was dose-dependently stimulated by moclobemide, whereas the plasma concentrations of growth hormone (hGH) and cortisol remained unchanged.

Steroid effects on central neurons and implications for psychiatric and neurological disorders

Acute and chronic stress as well as a number of psychiatric and neurological disorders are accompanied by profound disturbances of the HPA system. These neuroendocrine alterations act back on the central nervous tissue mainly via corticosteroids-affecting glucocorticoid and mineralocorticoid receptors. The major conclusions drawn from studies probing these receptors in clinical investigations are: (1) In many such conditions central corticosteroid receptors are weakened in their capacity to curtail spontaneous and stress-elevated corticosteroid levels; (2) the combined DEX-CRH test is the best neuroendocrine tool currently available for identifying HPA abnormalities in psychiatric patients; (3) in depression the decreased corticosteroid receptor capacity in transient, and antidepressants act through reinstatement of GR and MR function probably resulting in reduced hypothalamic CRH and AVP production; (4) several neurological disorders such as MS and HIV infection are often accompanied by altered HPA function, which has therapeutic implications; and (5) various corticosteroids, their biosynthetic precursors and their metabolites have differentiable effects on the sleep EEG, which can be attributed to their mode of action; specifically, steroids such as pregnenolone and DHEA most likely are produced in glia cells and act in a paracrine fashion at neurons, thus modifying the sleep EEG in humans in a manner that suggests their potential as memory enhancers.