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PubMed1997

Moclobemide for anxiety disorders: a focus on moclobemide for panic disorder.

Moclobemide is a reversible selective inhibitor of monoamine oxidase A. It has proven efficacy in a wide range of depressive disorders, including agitated anxious depression. In an international, multicentre, double-blind parallel-group study, the tolerability and efficacy of moclobemide were compared with that of the selective serotonin reuptake inhibitor fluoxetine. The target dose of moclobemide was 450 mg/day in the dose range of 300-600 mg/day, while the target dose for fluoxetine was 20 mg/day in the dose range of 10-30 mg/day. There were two consecutive studies. The first was an 8-week short-term study of acute adverse events, tolerability and efficacy. The efficacy data showed no significant difference between moclobemide and fluoxetine. Evaluation of the tolerability in a long-term study of up to 1 year is still in progress. A review of the moclobemide safety database for panic disorder with 624 patients showed a marginal increase in events with moclobemide compared with placebo for insomnia (11.2%), dizziness (4.5%) and dry mouth (3.7%), with rates for headaches and nausea lower for moclobemide than placebo. These data suggest moclobemide is a well tolerated and effective treatment for panic disorder.

Adult↗
PubMed1997

The International Multicenter Clinical Trial Group on Moclobemide in Social Phobia. Moclobemide in social phobia. A double-blind, placebo-controlled clinical study.

The primary objectives of this large multicenter study (n = 578) were to determine the efficacy and safety of moclobemide, 300 or 600 mg per day, for the treatment of social phobia. A double-blind fixed-dose parallel group study was conducted to compare the two different doses of moclobemide to placebo. After a 1-week placebo run-in period, patients were randomly assigned to one of the three treatment groups to receive the test compound for a 12-week period. Assessments were performed at screen, on baseline and on weeks 1, 2, 3, 4, 6, 8, 10, and 12. There were consistent, reliable and clinically meaningful drug effects and indications of a dose-response relationship. Statistical analysis of the results at both weeks 8 and 12 showed that 600 mg of moclobemide was effective and statistically significantly superior to placebo. The 300 mg dose also showed better efficacy than placebo on all measures of efficacy, and about half of them were statistically significantly different from placebo. Moclobemide was well tolerated. Adverse events, except for insomnia, were neither dose-related nor were there significant drug-placebo differences. The results indicate that 600 mg of moclobemide per day given b.i.d. is effective in social phobia, reducing the symptoms and the impairment associated with the disorder. The compound is well tolerated and safe.

Adult↗
PubMed1993

Effect of moclobemide on the psychophysiology of sleep/wake cycles: a neuroelectrophysiological study of depressed patients administered with moclobemide.

The effects of moclobemide, 450 mg/day, on sleep were investigated in 12 patients with major depression. The study was carried out over six weeks, divided into three periods: (1) treatment for one week with placebo and measurement to obtain baseline values; (2) treatment with moclobemide for four weeks; and (3) one week withdrawal period. Polygraphic sleep recording, all-night sleep-EEG spectral analysis, and diurnal EEG vigilance mapping were used to determine the effects of this antidepressant. An activating effect was observed, most marked during the early phase of treatment. The most noticeable effects were on REM sleep, affecting polysomnographic and spectral sleep EEG parameters. A REM sleep habituation phenomenon was observed, and a slight REM sleep rebound effect occurred early during withdrawal. The observed neuroelectrophysiological changes appear to be specific for moclobemide and differ from those brought about by other antidepressants.

Adult↗
PubMed1994

A multicentre comparative trial of moclobemide, imipramine and placebo in major depressive disorder. UK Moclobemide Study Group.

The reversible, selective monoamine oxidase A inhibitor moclobemide (450 mg daily) was compared with imipramine (150 mg daily) and placebo in a multicentre, controlled clinical trial lasting 6 weeks. Two hundred and forty-nine patients participated, with a major depressive episode according to DSM-III criteria, and whose initial Hamilton Depression Scale rating (HDRS) was at least 17. Clinical improvement, as determined by HDRS, was similar in the three treatment groups: 53% of the evaluable patients in the moclobemide group responded (i.e. a 50% reduction in HDRS), compared with 50% on imipramine and 51% on placebo. Tolerability was least on imipramine, largely due to the high frequency of anticholinergic side effects; moclobemide showed no difference from placebo in this respect.

Adolescent↗
PubMed2001

A randomized controlled trial comparing moclobemide and moclobemide plus interpersonal psychotherapy in the treatment of dysthymic disorder.

The authors compared the outcomes of 35 outpatients with dysthymic disorder randomized to receive either treatment with moclobemide and interpersonal therapy (IPT) or moclobemide and routine clinical management. Diagnosis was based on the ICD-10 symptom checklist. Patients were evaluated by trained raters using the 17-item Hamilton Rating Scale for Depression (Ham-D), Montgomery-Asberg Depression Rating Scale (MADRS), Global Assessment of Functioning, and Quality of Life and Satisfaction Questionnaire at baseline, 12, 24, and 48 weeks. Patients in both treatment groups showed statistically significant improvement in all measures across time. There was a nonsignificant trend toward lower scores on Ham-D and MADRS for patients in the moclobemide plus IPT group. Longer, better-powered trials should be carried out to study the efficacy of IPT plus antidepressant medication in the treatment of dysthymic disorder.

Adult↗
PubMed1995

A double-blind comparison of moclobemide and thioridazine versus moclobemide and placebo in the treatment of refractory, severe depression.

In a multicenter study of 78 severely depressed inpatients (44 women and 34 men; age range, 23 to 70 years), the efficacy, onset of efficacy, and tolerability of the reversible monoamine oxidase-A inhibitor moclobemide (450 mg/day) in combination with thioridazine (100 mg/day) were compared with those of moclobemide (450 mg/day) plus placebo. Patients enrolled met the DSM-III-R criteria for severe depression and had a severity score of at least 20 on the first 17 items of the Hamilton Rating Scale for Depression (HAM-D). Additionally, these patients had not responded to at least two standard antidepressants during the 2 years preceding screening and the mean duration of the current episode was 6 months. After a washout period of 3 to 5 days, patients were randomized to one of the two treatment groups, which at the outset had similar characteristics. Efficacy was assessed by the HAM-D, a depression observation rating for nurses, and a Clinical Global Impression (CGI) scale. Tolerability assessments included an overall rating, a description of adverse events, vital signs, electrocardiogram, and laboratory tests. After 4 weeks of therapy, both groups of patients showed significant improvements in HAM-D and CGI scores. The response rates (based on HAM-D > or = 50% decrease) were 74% for moclobemide/thioridazine and 77% for moclobemide/placebo, and according to CGI scores, 76 and 72% were "very much improved" or "much improved," respectively. Onset of effect was noted after 9.2 and 9.8 days, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2003

Moclobemide: therapeutic use and clinical studies.

Moclobemide is a reversible inhibitor of monoamine-oxidase-A (RIMA) and has been extensively evaluated in the treatment of a wide spectrum of depressive disorders and less extensively studied in anxiety disorders. Nearly all meta-analyses and most comparative studies indicated that in the acute management of depression this drug is more efficacious than placebo and as efficacious as tricyclic (or some heterocyclic) antidepressants or selective serotonin reuptake inhibitors (SSRIs). There is a growing evidence that moclobemide is not inferior to other antidepressants in the treatment of subtypes of depression, such as dysthymia, endogenous (unipolar and bipolar), reactive, atypical, agitated, and retarded depression as with other antidepressants limited evidence suggests that moclobemide has consistent long-term efficacy. However, more controlled studies addressing this issue are needed. For patients with bipolar depression the risk of developing mania seems to be not higher with moclobemide than with other antidepressants. The effective therapeutic dose range for moclobemide in most acute phase trials was 300 to 600 mg, divided in 2 to 3 doses. While one controlled trial and one long-term open-label study found moclobemide to be efficacious in social phobia, three controlled trials subsequently revealed either no effect or less robust effects with the tendency of higher doses (600 - 900 mg/d) to be more efficacious. Two comparative trials demonstrated moclobemide to be as efficacious as fluoxetine or clomipramine in patients suffering from panic disorder. Placebo-controlled trials in this indication are, however, still lacking. A relationship between the plasma concentration of moclobemide and its therapeutic efficacy is not apparent but a positive correlation with adverse events has been found. Dizziness, nausea and insomnia occurred more frequently on moclobemide than on placebo. Due to negligible anticholinergic and antihistaminic actions, moclobemide has been better tolerated than tri- or heterocyclic antidepressants. Gastrointestinal side effects and, especially, sexual dysfunction were much less frequent with moclobemide than with SSRIs. Unlike irreversible MAO-inhibitors, moclobemide has a negligible propensity to induce hypertensive crisis after ingestion of tyramine-rich food ("cheese-reaction"). Therefore, dietary restrictions are not as strict. However, with moclobemide doses above 900 mg/d the risk of interaction with ingested tyramine might become clinically relevant. After multiple dosing the oral bioavailability of moclobemide reaches almost 100%. At therapeutic doses, moclobemide lacks significant negative effects on psychomotor performance, cognitive function or cardiovascular system. Due to the relative freedom from these side effects, moclobemide is particularly attractive in the treatment of elderly patients. Moclobemide is a substrate of CYP2C19. Although it acts as an inhibitor of CYP1A2, CYP2C19, and CYP2D6, relatively few clinically important drug interactions involving moclobemide have been reported. It is relatively safe even in overdose. The drug has a short plasma elimination half-life that allows switching to an alternative agent within 24 h. Since it is well tolerated, therapeutic doses can often be reached rapidly upon onset of treatment. Steady-state plasma levels are reached approximately at one week following dose adjustment. Patients with renal dysfunction require no dose reduction in contrast to patients with severe hepatic impairment. Cases of refractory depression might improve with a combination of moclobemide with other antidepressants, such as clomipramine or a SSRI. Since this combination has rarely been associated with a potentially lethal serotonin syndrome, it requires lower entry doses, a slower dose titration and a more careful monitoring of patients. Combination therapy with moclobemide and other serotonergic agents, or opioids, should be undertaken with caution, although no serious adverse events have been published with therapeutic doses of moclobemide to date. On the basis of animal data the combined use of moclobemide with pethidine or dextropropoxyphene should be avoided. There is no evidence that moclobemide would increase body weight or produce seizures. Some preclinical data suggest that moclobemide may have anticonvulsant property.

Adult↗
PubMed1989

Neurochemical profile of moclobemide, a short-acting and reversible inhibitor of monoamine oxidase type A.

Moclobemide belongs to a new generation of short-acting, reversible, monoamine oxidase (MAO) inhibitors. In vitro (rat brain homogenates) moclobemide inhibits MAO-A selectively with lower potency than many of the reference MAO inhibitors. However, when measured ex vivo in the rat, the potency of moclobemide is similar to that of reference compounds. In vivo the drug induces a dose-dependent, short-lasting (8-16 hr) and preferential inhibition of MAO-A in the brain and both MAO-A and MAO-B inhibition in extracerebral organs (liver, small intestine and kidney). In the extracerebral tissues of the rat moclobemide induces marked peripheral MAO-B inhibition due to rapid and extensive biotransformation of its morpholine ring. The active molecular species is probably the metabolite Ro 16-6491. The moderate MAO-B inhibition measured after moclobemide intake in human platelets indicates that only minor amounts of Ro 16-6491 are formed in humans. Virtually all metabolites of moclobemide so far identified have been tested in vitro and ex vivo in the rat and proved to be either equipotent or, mostly, less effective than moclobemide as MAO-A inhibitors. In liver homogenates of moclobemide-treated rats MAO-A activity recovers during dialysis or simple incubation at 37 degrees C, suggesting a biodegradation of moclobemide and/or the moclobemide-derived active metabolite(s) by MAO itself or a slow dissociation of the active inhibitory species from the enzyme. Similar to other MAO-A inhibitors, moclobemide induces an increase in the rat brain levels of 5-hydroxytryptamine, norepinephrine and dopamine and a concomitant decrease of their deaminated metabolites. These effects are of short duration (8-16 hr) and parallel the time course of MAO-A inhibition. Moclobemide administered subchronically down-regulates beta adrenoceptors as shown by binding experiments with brain cortical membranes using dihydroalprenolol as ligand. In vitro MAO inhibition by moclobemide is specific in that the compound does not affect other amine oxidases or monoamine uptake mechanisms; furthermore, it does not interact with various neurotransmitter or drug receptor sites. In conclusion, a large body of preclinical evidence characterizes moclobemide as a short-acting and reversible MAO-inhibitor. The neurochemical profile of moclobemide indicates clearly that this nonhydrazine nonhepatotoxic MAO-A inhibitor represents a novel and safe drug for treatment of affective disorders.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2003

Moclobemide poisoning: toxicokinetics and occurrence of serotonin toxicity.

AIMS: To investigate the spectrum of toxicity of moclobemide overdose, the occurrence of serotonin toxicity, and to estimate toxicokinetic parameters. METHODS: All moclobemide overdoses presenting over a 10-year period to the Hunter Area Toxicology Service were reviewed. Clinical features, complications, length of stay (LOS) and intensive care (ICU) admission rate were extracted from a standardized, prospectively collected database. Comparisons were made between moclobemide alone and moclobemide with a serotonergic coingestant poisoning. Serotonin toxicity was defined by a combination of Sternbach's criteria and a clinical toxicologist's diagnosis. In five patients serial moclobemide concentrations were measured. Time to maximal plasma concentration (Tmax), peak plasma concentration (Cmax) and terminal elimination half-lives were estimated. RESULTS: Of 106 included patients, 33 ingested moclobemide alone, 21 ingested moclobemide with another serotonergic agent (in some cases in therapeutic doses) and 52 ingested moclobemide with a nonserotonergic agent. Eleven (55%) of 21 patients coingesting a serotonergic drug developed serotonin toxicity, which was significantly more than one (3%) of 33 moclobemide-alone overdoses (odds ratio 35, 95% confidence interval 4, 307; P < 0.0001). In six of these 21 cases severe serotonin toxicity developed with temperature >38.5 degrees C and muscle rigidity requiring intubation and paralysis. The 21 patients had a significantly increased LOS (34 h) compared with moclobemide alone overdoses (12 h) (P < 0.0001) and a significantly increased ICU admission rate of 57% vs. 3% (P < 0.0001). Time to peak plasma concentration was delayed in two patients where prepeak samples were obtained. Cmax increased slightly with dose, but all three patients ingesting > or = 6 g vomited or had charcoal. The mean elimination half-life of moclobemide in the five patients in whom serial moclobemide concentrations were measured was 6.3 h and elimination was first order in all cases. There was no evidence of a dose-dependent increase in half-life. CONCLUSIONS: The effects of moclobemide alone in overdose are minor, even with massive ingestions. However, moclobemide overdose in combination with a serotonergic agent (even in normal therapeutic doses) can cause severe serotonin toxicity. The elimination half-life is prolonged by two to four times in overdose, compared with that found in healthy volunteers given therapeutic doses. This may be a result of wide interindividual variation in overall elimination, also seen with therapeutic doses, but appears not to be due to saturation of normal elimination pathways.

Adult↗
PubMed1996

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.

Age Factors↗
PubMed1989

Review of comparative clinical trials. Moclobemide vs tricyclic antidepressants and vs placebo in depressive states.

Moclobemide is a reversible monoamine oxidase inhibitor (MAOI) which preferentially inhibits type-A MAO. In the present communication the results obtained with moclobemide in various clinical trials are reviewed. To this day, the antidepressant efficacy of moclobemide has been compared to that of placebo in four trials. The antidepressant efficacy of moclobemide (300-600 mg/d; N = 164) was found to be superior to that of placebo (N = 162) and comparable to that of imipramine (100-200 mg/d; N = 164) in a 6-w., double-blind, multicentre study, in patients suffering from a Major Depressive Episode (DSM-III). Two smaller trials, strongly suggest that moclobemide is more efficacious than placebo for the treatment of endogenous depression (ICD-9) and for the treatment of Dysthymic Disorders (DSM-III). The antidepressant efficacy of moclobemide was compared to that of imipramine, desipramine, clomipramine and amitriptyline. The antidepressant efficacy of moclobemide (300-600 mg/d; N = 189) was found to be comparable to that of imipramine (100-200 mg/d; N = 192) in a 4-w., double-blind, multicentre study, in patients suffering from a Major Depressive Episode. This finding is supported by the results obtained in 12 other smaller studies, using either imipramine, desipramine, clomipramine or amitriptyline as comparator drug. When the tolerability of moclobemide, as judged by reported and observed adverse events, is compared to that of placebo, it appears that only nausea is reported significantly more frequently with moclobemide than with placebo (9.5% vs 4.8%). In the trials comparing moclobemide to tricyclic antidepressant drugs (TCAs), the tolerability of moclobemide was constantly found to be superior to that of the TCAs; in particular the incidence of anticholinergic side effects was low with moclobemide and was significantly higher with the TCAs. The cardiovascular tolerability of moclobemide tended to be superior to that of the TCAs. Physical examination, hematology and clinical chemistry did not seem to be affected by treatment in any of the studies summarized in this review.

Antidepressive Agents, Tricyclic↗
PubMed1998

Comparison of the effects of moclobemide and selegiline on tyramine-evoked mydriasis in man.

AIMS: To examine the feasibility of using the human iris in vivo for the assessment of the interaction between tyramine and monoamine oxidase (MAO) inhibitors. To examine the relative roles of the two forms of MAO in terminating the response to sympathomimetic amines in the iris, by comparing the effects of single oral doses of moclobemide, a selective MAO-A inhibitor, and selegiline, a selective MAO-B inhibitor, on mydriatic responses to tyramine. METHODS: Twelve healthy male volunteers participated in three monthly sessions, each associated with ingestion of one capsule (moclobemide 450 mg, selegiline 10 mg, or placebo), according to a double-blind, balanced, cross-over design. Tyramine hydrochloride eye-drops (75 mM, 2 x 10 microl) were instilled three times in the left conjuctival sac at 40 min intervals. Pupil diameter was monitored with a binocular infrared television pupillometer before and for 4.5 h after ingestion of the capsule. The pupillary response to tyramine was expressed as the area under the pupil diameter x time curve (arbitrary units). A blood sample was taken before and 2 h after ingestion of the capsule, for the assay of platelet MAO-B activity, and plasma 3,4-dihydroxyphenylglycol (DHPG) concentration, an index of MAO-A activity. Platelet MAO activity was assayed radiochemically, using [14C]-phenylethylamine as substrate, and plasma DHPG by high performance liquid chromatography (h.p.l.c.). The results were analysed using analysis of variance with repeated measures, followed by Bonferroni's corrected t-test, using a significance criterion of P < 0.05. RESULTS: Both moclobemide and selegiline, compared with placebo, caused significant miosis in the right (untreated) eye. The changes in pupil diameter (mm +/- s.e. mean) from the pretreatment measurement were: placebo -0.09 +/- 0.07, moclobemide -0.52 +/- 0.09, selegiline -0.26 +/- 0.1. The mydriatic response to tyramine was potentiated by moclobemide, compared with the response recorded in the presence of placebo. The responses to tyramine (arbitrary units +/- s.e. mean) were: placebo 77.08 +/- 11.65, moclobemide 140.25 +/- 18.9, selegiline 72.75 +/- 12.35. Both moclobemide and selegiline significantly reduced platelet MAO activity, compared with placebo. The changes in platelet MAO activity (nmol h(-1) mg(-1) protein +/- s.e. mean) from the pretreatment level were: placebo 0.5 +/- 0.62, moclobemide -6.7 +/- 0.66, selegiline -17.7 +/- 0.87. Moclobemide significantly reduced plasma DHPG concentration, compared with placebo. The changes in plasma DHPG concentration (nmol l(-1) +/- s.e. mean) from the pretreatment level were: placebo -0.01 +/- 0.24, moclobemide -4.98 +/- 0.32, selegiline -0.51 +/- 0.26. CONCLUSIONS: The potentiation of tyramine-evoked mydriasis by moclobemide is likely to reflect the inhibition of MAO-A activity in the iris, consistent with the activity of this enzyme in sympathetic nerve terminals. The lack of effect of selegiline on tyramine-evoked mydriasis argues against a role of MAO-B in terminating the effects of sympathomimetic amines in the iris. The effects of the two drugs on platelet MAO activity and plasma DHPG concentration are in agreement with previous reports and consistent with the relative selectivity of moclobemide for MAO-A and of selegiline for MAO-B. The miosis caused by the two MAO inhibitors is likely to be due to a central sympatholytic action of the drugs.

Adult↗
PubMed1997

Efficacy and tolerability of moclobemide in comparison with placebo, tricyclic antidepressants, and selective serotonin reuptake inhibitors in elderly depressed patients: a clinical overview.

OBJECTIVE: To review the efficacy and safety of moclobemide in comparison with TCAs (for our purposes, "TCAs" will represent tricyclic and tetracyclic antidepressants, including maprotilin and mianserin) and selective serotonin reuptake inhibitors (SSRIs) in elderly depressed patients. METHODS: The efficacy data reviewed were obtained from the following sources: 1) results of published studies in the elderly; 2) data on patients aged > or = 60 years extracted from all available controlled trials in adults (> or = 18 years) in which moclobemide was compared with TCAs or SSRIs; and 3) the adverse events were extracted for patients aged > or = 60 years from the safety data base of all available comparative short-term studies with moclobemide versus TCAs, SSRIs, or placebo and of long-term studies with moclobemide. RESULTS: The data show that moclobemide is an effective antidepressant in depressed patients aged > or = 60 years. The response rate to moclobemide was 50% to 55% in this population. Moclobemide was more effective than placebo and was of similar efficacy to the TCAs and the more recently introduced SSRIs. The tolerability of moclobemide was rated as "very good" or "good" in almost 90% of these patients, which was better than the tolerability of TCAs and similar to that of SSRIs. Patients without any adverse events were more frequently found in the moclobemide group than in those treated with TCAs (P < 0.01) or SSRIs (P < 0.01). Adverse events of the anticholinergic type were more frequent with TCAs than with moclobemide (P < 0.001), and nausea was found 3 times more frequently with SSRIs than with moclobemide (P < 0.01). CONCLUSIONS: Moclobemide is an effective and well-tolerated antidepressant for the treatment of elderly depressed patients.

Aged↗
PubMed2001

Characterization of moclobemide N-oxidation in human liver microsomes.

1. Moclobemide underdergoes morpholine ring N-oxidation to form a major metabolite in plasma Rol2-5637. 2. The kinetics of moclobemide N-oxidation in human liver microsomes (HLM) (n = 6) have been investigated and the mixed-function oxidase enzymes catalysing this reaction have been identified using inhibition, enzyme correlation, altered pH and heat pretreatment experiments. 3. N-oxidation followed single enzyme Michealis-Menten kinetics (0.02-4.0 mm). Km app and Vmax ranged from 0.48 to 1.35 mM (mean +/- SD) 0.77 +/- 0.34 mM) and 0.22 to 2.15 nmol mg(-1) min(-1) (1.39 +/- 0.80 nmol mg(-1) respectively. 4. The N-oxidation of moclobemide strongly correlated with benzydamine N-oxidation a probe reaction for flavin-containing monoxygenase (FMO) activity (0.1 mM moclobemide, rs = 0.81, p < 0.005; 4 mM moclobemide, rs = 0.94, p = 0.0001). Correlations were observed between moclobemide N-oxidation and specific cytochromre P450 (CYP) activities at both moclobemide concentrations (0.1 mM moclobemide, CYP2C19 0.66, p < 0.05; 4 mM moclobemide, CYP2E1 rs = 0.56, p < 0.05). 5. The general P450 inhibitor, N-benzylimidazole, did not affect the rate of Rol2-5637 formation (0% inhibition versus control) (at 1.3 mM moclobemide. Furthermore, the rate of Ro12-5637 formation in HLM was unaffected by inhibitors Or substrates of specific P450s (< 10% inhibition versus control). 6. Heat pretreatment of HLM in the absence of NADPH (inactivating FMOs) resulted in 97% inhibition of Ro12-5637 formation. N-oxidation activity was greatest when incubated at pH 8.5. These results ilre consistent with the reaction being FMO medialtetd . 7. In conclusion, moclobemide N-oxidation activity has been observed in HLM in vitro and the reaction is predominantly catalysed by FMOs with a potentially small contribution from cytochrome P450 isoforms.

Benzamides↗
PubMed1989

Preclinical profiles of the novel reversible MAO-A inhibitors, moclobemide and brofaromine, in comparison with irreversible MAO inhibitors.

Acceptance into clinical practice of monoamine oxidase (MAO) antidepressants requires unequivocal evidence that novel, non-hepatotoxic and reversible MAO-A inhibitors carry little or no risk of inducing severe hypertensive crises (cheese effect). This study summarizes the most relevant preclinical aspects which differentiate the novel reversible MAO-A inhibitors moclobemide and brofaromine, from previous irreversible MAO inhibitors of the old generation, particularly phenelzine and tranylcypromine. Moclobemide and brofaromine bear no chemical relation to irreversible inhibitors such as hydrazine derivatives (phenelzine) or aminocyclopropyl derivatives (tranylcypromine). Experiments in rats show that moclobemide and brofaromine increase the level of serotonin (5-hydroxytryptamine) and decrease that of 3,4-dihydroxyphenylacetic acid for only 16-24 hours. In vitro, moclobemide and brofaromine behave as mechanism-based, enzyme-activated inhibitors since their intrinsic inhibitory activity increases with the duration of their interaction with the enzyme in tissue homogenates. In contrast to irreversible monoamine oxidase inhibitors, which are much more potent in vitro than in vivo, moclobemide has the characteristic to be virtually equipotent in vitro and in vivo. MAO-A inhibition induced by moclobemide in the rat in vivo was rapidly reversed by simply incubating liver homogenates at 37 degrees C in the absence of the inhibitor, indicating a rapid metabolic inactivation of moclobemide in vitro. This reversibility is a distinctive feature of moclobemide, when compared with brofaromine or irreversible MAO inhibitors. Hepatotoxicity is not an inherent property of MAO inhibitors indeed, moclobemide or brofaromine, due to their chemical structures, cannot be converted into isopropyl hydrazine, the hepatotoxic metabolite of iproniazid suspected to induce liver necrosis. Results from preclinical and clinical investigations demonstrate that moclobemide and brofaromine, in contrast to tranylcypromine and phenelzine, very weakly potentiate the pressor effects of orally administered tyramine. In conclusion, the reversible MAO-A inhibitors moclobemide and brofaromine, due to their well-documented safety characteristics, to their lack of anticholinergic-effects and to their good tolerability, will provide innovative tools for clarifying the role of MAO-A inhibitors in the treatment of endogenous and atypical depressive states.

Animals↗
PubMed1997

Moclobemide and imipramine in chronic depression (dysthymia): an international double-blind, placebo-controlled trial. International Collaborative Study Group.

An international, multicenter, placebo-controlled study was undertaken to determine the safety and antidepressant efficacy of moclobemide, a new reversible inhibitor of monoamine oxidase A, and imipramine in the treatment of dysthymia (DSM-III-R). A total of 315 patients were enrolled and randomly assigned to an 8-week treatment in one of three groups (moclobemide, imipramine and placebo). Patients were male or female outpatients aged between 18 and 65 years meeting DSM-III-R criteria for dysthymia, primary type, with late or early onset. Of the patients in each group 85% completed the 8-week treatment period. The percentage of patients who no longer fulfilled DSM-III-R symptom criteria at treatment endpoint was significantly higher in the moclobemide (60%) and imipramine (49%) treatment groups than in the placebo group (22%). Differences to placebo were also statistically significant both for moclobemide and for imipramine on the other efficacy variables (i.e. Hamilton Rating Scale for Depression, final overall efficacy assessment, Clinical Global Impression and symptom check list self-rating). A significant superiority of moclobemide and imipramine over placebo was found in pure dysthymia and in double-depression, as well as in early and late onset subgroups. In early onset cases, moclobemide was significantly more effective than was imipramine on the Hamilton Rating Scale for Depression. Anticholinergic symptoms and sleepiness were significantly more frequent side effects on imipramine than on moclobemide or on placebo, and the investigators' final overall assessment of tolerability significantly favoured moclobemide over imipramine. This study demonstrates the efficacy of high dose moclobemide (mean dose 675 mg/day) and high dose imipramine (220 mg/day) against placebo in the treatment of dysthymia. Moclobemide was better tolerated than was imipramine.

Adolescent↗