Discovery of aryl sulfonamide-selective Nav1.7 inhibitors with a highly hydrophobic ethanoanthracene core.

Nav1.7 channels are mainly distributed in the peripheral nervous system. Blockade of Nav1.7 channels with small-molecule inhibitors in humans might provide pain relief without affecting the central nervous system. Based on the facts that many reported Nav1.7-selective inhibitors contain aryl sulfonamide fragments, as well as a tricyclic antidepressant, maprotiline, has been found to inhibit Nav1.7 channels, we designed and synthesized a series of compounds with ethanoanthracene and aryl sulfonamide moieties. Their inhibitory activity on sodium channels were detected with electrophysiological techniques. We found that compound 10o potently inhibited Nav1.7 channels stably expressed in HEK293 cells (IC50 = 0.64 ± 0.30 nmol/L) and displayed a high Nav1.7/Nav1.5 selectivity. In mouse small-sized dorsal root ganglion neurons, compound 10o (10, 100 nmol/L) dose-dependently decreased the sodium currents and dramatically suppressed depolarizing current-elicited neuronal discharge. Preliminary in vivo experiments showed that compound 10o possessed good analgesic activity: in a mouse visceral pain model, administration of compound 10o (30-100 mg/kg, i.p.) effectively and dose-dependently suppressed acetic acid-induced writhing.

Antidepressant stimulation of CDP-diacylglycerol synthesis does not require monoamine reuptake inhibition.

BACKGROUND: Recent studies demonstrate that diverse antidepressant agents increase the cellular production of the nucleolipid CDP-diacylglycerol and its synthetic derivative, phosphatidylinositol, in depression-relevant brain regions. Pharmacological blockade of downstream phosphatidylinositide signaling disrupted the behavioral antidepressant effects in rats. However, the nucleolipid responses were resistant to inhibition by serotonin receptor antagonists, even though antidepressant-facilitated inositol phosphate accumulation was blocked. Could the neurochemical effects be additional to the known effects of the drugs on monoamine transmitter transporters? To examine this question, we tested selected agents in serotonin-depleted brain tissues, in PC12 cells devoid of serotonin transporters, and on the enzymatic activity of brain CDP-diacylglycerol synthase - the enzyme that catalyzes the physiological synthesis of CDP-diacylglycerol. RESULTS: Imipramine, paroxetine, and maprotiline concentration-dependently increased the levels of CDP-diacylglycerol and phosphatidylinositides in PC12 cells. Rat forebrain tissues depleted of serotonin by pretreatment with p-chlorophenylalanine showed responses to imipramine or maprotiline that were comparable to respective responses from saline-injected controls. With fluoxetine, nucleolipid responses in the serotonin-depleted cortex or hippocampus were significantly reduced, but not abolished. Each drug significantly increased the enzymatic activity of CDP-diacylglycerol synthase following incubations with cortical or hippocampal brain tissues. CONCLUSION: Antidepressants probably induce the activity of CDP-diacylglycerol synthase leading to increased production of CDP-diacylglycerol and facilitation of downstream phosphatidylinositol synthesis. Phosphatidylinositol-dependent signaling cascades exert diverse salutary effects in neural cells, including facilitation of BDNF signaling and neurogenesis. Hence, the present findings should strengthen the notion that modulation of brain phosphatidylinositide signaling probably contributes to the molecular mechanism of diverse antidepressant medications.

Lipidomic analyses of the mouse brain after antidepressant treatment: evidence for endogenous release of long-chain fatty acids?

Recently, there has been considerable interest in a possible link between changes in brain polyunsaturated fatty acids, neural membrane phospholipid degradation, serotonergic neurotransmission, and depression. The present study aims to examine effects of antidepressants on lipids in different regions of the brain at individual molecular species level, using the novel technique of lipidomics. Balb/C mice received daily intraperitoneal (i.p.) injections of 10 mg/kg of the antidepressants maprotiline, fluoxetine and paroxetine for 4 wk. The prefrontal cortex, hippocampus, striatum and cerebellum were harvested, and lipid profiles compared to those of saline-injected mice. Treatment with maprotiline and paroxetine, but not fluoxetine, resulted in significant decreases in phosphatidylcholine (PC) species, PC36:1, PC38:3, PC40:2p, PC40:6, PC40:5, PC42:7p, PC42:6p and PC42:5p in the prefrontal neocortex. The decreases in phospholipids were accompanied by increases in lysophospholipid species, lysoPC16:0, lysoPC18:2 and lysoPC18:0 in the prefrontal cortex, indicating increase in phospholipase A2 activity and possible release of long-chain fatty acids. Maprotiline and paroxetine treatment also resulted in decreases in sphingomyelin and increases in several ceramide species in the prefrontal cortex. It is postulated that endogenous release of long-chain fatty acids may be related to the mechanism of action of maprotiline and paroxetine.

The synergistic interaction between morphine and maprotiline after intrathecal injection in rats.

BACKGROUND: Antidepressant drugs act as potent inhibitors of norepinephrine and/or serotonin reuptake and are widely used with opioids for the treatment of chronic pain. The mechanism of this increased analgesic action is unclear. We compared the antinociceptive effects of the intrathecal administration of morphine with that of a nonselective (amitriptyline) or selective (maprotiline or citalopram) antidepressant drug using the thermal withdrawal test in rats. We also investigated the possible mechanisms involved in the interactions of these drugs. METHODS: Male Wistar rats were anesthetized with sevoflurane and administered morphine and antidepressant drugs, or saline, through intrathecal injection. The antinociceptive effect was evaluated using the thermal withdrawal test before and after drug administration. The time for the withdrawal reaction was expressed as percentage of maximum possible effect (MPE). Animals were also pretreated with yohimbine (a nonselective alpha2-adrenergic antagonist) and naloxone (a nonselective opioid antagonist) for mechanism of action studies. Pharmacologic interaction was evaluated using isobolographic analysis of simultaneous administration of fixed proportions of maprotiline and morphine. RESULTS: Single intrathecal administration of morphine (2 microg), amitriptiline (125 microg), citalopram (144 microg), and maprotiline (1.25 microg) produced 51.6% +/- 8.9%, 10.3% +/- 3.2%, 33.8% +/- 5.2%, and 48.5% +/- 9.2% MPE, respectively. The antinociceptive effect of morphine was increased when combined with amitriptyline (91.3% +/- 4.6% MPE) and maprotiline (86.9% +/- 9.2% MPE) but not with citalopram (40.6% +/- 4.6% MPE). Coadministration of maprotiline increased the antinociceptive duration of morphine by 4-fold (from 120 to 480 min), which was reversed by pretreatment with the alpha-2 adrenoceptor inhibitor, yohimbine, and the mu-type opioid receptor antagonist, naloxone. Isobolographic analysis demonstrated a synergistic interaction between morphine and maprotiline. CONCLUSIONS: Selective norepinephrine reuptake inhibitors can significantly increase the intensity and duration of morphine antinociceptive activity via both alpha(2)-adrenergic and opioid receptors. This interaction was not observed with the selective serotonin inhibitor, citalopram.

Mouse strain differences in the unpredictable chronic mild stress: a four-antidepressant survey.

There have been few comparisons of strains and antidepressants in the unpredictable chronic mild stress (UCMS) paradigm in mice. This study was undertaken to determine the influence of such factors using four antidepressants drugs including the tricyclics imipramine (20 mg/(kgday)) and desipramine (10 mg/(kgday)), the tetracyclic maprotiline (20 mg/(kgday)) and the selective serotonin reuptake inhibitor (SSRI) fluoxetine (10mg/(kgday)) in both Swiss and BALB/c mice. A 6-week UCMS regimen induced deterioration of the coat state and decreased grooming behaviours in the splash test in BALB/c mice but not Swiss mice. The four antidepressants reversed the UCMS-induced effects in BALB/c mice in both measures. However, imipramine and fluoxetine reached significance in the splash test while desipramine and maprotiline displayed only a trend. In conclusion, these results emphasize that BALB/c mice are more sensitive than Swiss mice for studying the effects of the UCMS model as well as for testing antidepressant-like properties.

Acute effects of maprotiline on learning, anxiety, activity and analgesia in male and female mice.

The acute effects of maprotiline (2.5, 5, 10, 15, 20 or 25 mg/kg) on learning, anxiety, activity and analgesia in male and female mice were evaluated. In addition to inhibitory avoidance learning, anxiety and locomotor activity were measured in the same animals using an elevated plus-maze. A study of the acute effects of maprotiline (15, 20 or 25 mg/kg) on analgesia was carried out in naive animals of both sexes. Maprotiline impaired inhibitory avoidance at doses of 15, 20 or 25 mg/kg. The highest dose produced an anxiolytic effect in females, and the doses of 20 and 25 mg/kg reduced locomotor activity. Analgesia was observed with the highest dose. The impairment of inhibitory avoidance by maprotiline would seem to be independent of the drug's influence on anxiety, is not shadowed by an instrumental performance deficit and, at least in the case of the highest dose, could be influenced by the drug's effects on analgesia. It is hypothesized that acquisition is the memory process principally affected by maprotiline, and in particular stimuli processing. The lack of sex differences in the effects of maprotiline on inhibitory avoidance supports the generalization of findings previously obtained only in males.

Maprotiline treatment in depression. A perspective on seizures.

Eleven McLean Hospital (Belmont, Mass) depressed patients who experienced seizures while receiving maprotiline hydrochloride are presented, as are data on 87 cases reported to the manufacturer (Ciba-Geigy). Most seizures occurred at high dosages, sometimes after many weeks at a stable dose, but neither rapid dosage escalation nor high drug plasma levels seemed related to seizure occurrence. Our experience suggests that a long-acting metabolite might be responsible for seizures. Ten of the 11 McLean Hospital seizures occurred in patients receiving dosages outside of the since-revised current dosage guidelines, as did 60% of the seizures reported to the company. Data in this study suggest that reductions in maximum dosage of maprotiline prescribed after the initial six weeks of treatment could result in a further decrease in risk of seizures beyond that obtained from previous alterations in regimens.

Bioavailability and kinetics of maprotiline.

Six male subjects received simultaneously single 50-mg oral doses of a maprotiline hydrochloride tablet and a trideuterated maprotiline hydrochloride aqueous solution. No side effects or other problems were encountered. The blood levels of unlabeled and isotope-labeled maprotiline for each subject were essentially superimposable. Peak levels, averaging about 50 ng/ml, were attained between 8 and 24 hr after drug. The biologic t1/2 (beta-phase) averaged 58 hr for the unlabeled and 60.5 hr for the labeled drug. The total areas under the curves (extended to time infinity) averaged 3,862 and 3,944 ng . hr/ml for maprotiline and trideuterated maprotiline, respectively (differences between the two are not significant). At the 95% degree of confidence the Westlake confidence limits show less than 10% differences between the formulations with respect to area under the curve data (calculated both to 168 hr and extended to time infinity), peak blood levels, and biologic t1/2s. There were no differences between formulations with respect to times of peak concentrations. Estimates were made for apparent volumes of distribution (about 1,000 l), apparent blood clearance (about 14 l/hr), lag times (about 1.42 hr for tablets and 1.31 hr for solution), and absorption rate constants (about 0.34 hr-1 for the tablets and 0.42 hr-1 for the solution).

Prophylactic efficacy of maprotiline on unipolar depression relapse.

BACKGROUND: Although antidepressant medications have been in use for about 30 years, the question remains about their utility in the prophylaxis of recurrent depression. The purpose of this study was to evaluate the efficacy of maprotiline, a tetracyclic antidepressant, for depression prophylaxis. METHOD: We conducted a vast, prospective, multicenter, double-blind, placebo-controlled study of 1141 outpatients suffering from depression and treated with maprotiline or placebo for 1 year. The very large size of the study population allowed for the testing of two drug doses. The study design included a pre-inclusion treatment phase that assured that all study patients had recently suffered from a depressive episode and were in remission at the time they were randomized into two treatment groups (1 and 1/2 tablet of maprotiline 75 mg) and two control groups (1/2 and 1 tablet of placebo). RESULTS: The actuarial relapse rate at 1 year was 16% for maprotiline 75 mg, 1 tablet; 23.8% for maprotiline 75 mg, 1/2 tablet; 31.5% for 1 tablet placebo, and 37.5% for 1/2 tablet placebo. The difference between each group is statistically significant, except for the difference between the two placebo groups. The actuarial incidence of adverse drug reactions during the year was not statistically significant between the treatment and control groups. CONCLUSIONS: This study demonstrates maprotiline's prophylactic effectiveness for depressive relapses, the 75-mg dose being more effective than the 37.5-mg dose. The patients' tolerance of maprotiline therapy was satisfactory at both doses with prolonged prescription.

Acute therapy of depression.

The acute therapy (the initial 8 weeks of treatment) of depression (including the whole spectrum of "less than major," "major," and "more than major") has been reviewed comparing the old tricyclics with the new generations (especially mianserin, moclobemide, and the serotonin selective reuptake inhibitors (SSRIs), i.e., citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline). The Hamilton Rating Scale for Depression has been used to measure clinical efficacy. Statistically, the method of meta-analysis has been applied. The results showed that the SSRIs and moclobemide are equal to the tricyclics. Mianserin is inferior to tricyclics as well as to SSRIs. The antidepressive profile of the SSRIs is nonsedation but still with anxiolytic effects. The safety profile of the SSRIs is much more benign than that of the tricyclics.

Depression in the elderly: pharmacologic considerations in treatment.

The pharmacologic treatment of depression in the aged is complicated by an increased frequency of concurrent medical disease and multiple drug use. In addition, age-related physiologic changes may alter the pharmacokinetics and pharmacodynamics of the antidepressant medications. As a consequence, the variability of response and the incidence of adverse effects are increased in the elderly. The clinical implications of these factors and guidelines for the use of antidepressants in the elderly are discussed.

Toward a biochemical classification of depressive disorders. III: Pretreatment urinary MHPG levels as predictors of response to treatment with maprotiline.

Pretreatment urinary MHPG levels were examined in 28 depressed patients as a possible predictor of response to treatment with maprotiline, a tetracyclic antidepressant that exerts potent effects on norepinephrine uptake, but has little effect on serotonin uptake. Maprotiline was administered in doses up to 150 mg/day during the first 2 weeks after which time the dose could be increased incrementally up to 300 mg/day if indicated clinically. At 2 weeks, patients with low pretreatment urinary MHPG levels responded more favorably to treatment than did patients with high MHPG levels. At 4 weeks, patients with low MHPG levels continued to show more favorable responses; however, differences between the two groups were less clear-cut than at 2 weeks. The findings suggest the patients with low pretreatment urinary MHPG levels are more sensitive to, and respond more rapidly to, treatment with maprotiline than patients with high pretreatment urinary MHPG levels.

Interaction of opioids with antidepressant-induced antinociception.

The antinociceptive activity of antidepressant drugs is poorly understood. In this study, using the acetic acid writhing test in mice, the antinociception produced by clomipramine (CLO), maprotiline (MAP), imipramine (IMI), and zimelidine (ZIM) was tested and correlated with opioid drugs. All the compounds displayed a significant dose-dependent antinociception, which was not antagonized by naloxone (NX) or naltrexone (NTX). The administration of morphine (M) plus CLO, MAP, IMI or ZIM resulted in a significant additive effect that was antagonized by 1 or 10 mg/kg NX or NTX, except in the case of IMI. This finding suggests that the additive effect seems to be partially due to activation of opioid receptors, except for the case of imipramine. However, aminophylline, a non-selective blocker of A1/A2 adenosine receptors, significantly antagonized the antinociceptive activity of CLO, IMI, MAP and ZIM, demonstrating an interaction at the level of adenosine receptors. This work suggests that the antinociceptive activity of antidepressants could be dependent on critical levels of free 5-HT and NE at receptor(s) site(s) in CNS and on their interaction with opioid and adenosine receptors.

The dexamethasone suppression test and antidepressant response in major depression.

UNLABELLED: We conducted a prospective open pilot study of 34 consecutively admitted patients with the DSM-III diagnosis of MD who were admitted to a general psychiatric unit. Patients underwent a 1 mg DST and were randomly assigned to treatment with either maprotiline or trazodone. Antidepressant dosages were increased as tolerated clinically and according to treatment response. RESULTS: mean final oral doses were 193 mg for maprotiline and 328 mg for trazodone. The mean treatment duration was 4.5 weeks for maprotiline and 5.9 weeks for the trazodone group. Of these 34 patients 44% showed DST nonsuppression (41% maprotiline, 45% trazodone). Seventy-six per cent of the patients responded to treatment (76% for both drugs) as defined by GAS. Eighty-seven per cent of the nonsuppressors responded to treatment (86% maprotiline, 88% trazodone) and 68% of the suppressors responded (70% maprotiline, 67% trazodone). Of the eight treatment nonresponders six showed DST suppression. The implications of these findings are discussed.

Multicenter evaluation of maprotiline hydrochloride for treatment of depression.

Maprotiline hydrochloride tablets were given to 266 patients with either a dysthymic disorder or a major depressive disorder. The mean starting dosage was 70.2 mg/day in patients younger than 60 years of age and 68.6 mg/day in those aged 60 years and over. For patients completing at least four weeks of treatment, the mean final dosage was 127.6 mg/day in younger patients and 100.0 mg/day in geriatric patients. Follow-up evaluations of response and adverse effects were made at each of the following intervals after the start of therapy: one week, two to three weeks, four to five weeks, and six weeks or more. Assessment of response was based on the physicians' evaluations of overall improvement and improvement in sleep pattern, anxiety level, mood, and drive. Eighteen patients never returned and were excluded from all assessments. The remaining patients were evaluated for observations recorded within the foregoing time intervals. A rapid onset of action was evident in the fact that 73% of evaluated patients had at least a minimal response after one week of treatment, and after six weeks 76% had achieved moderate or marked improvement in their overall condition. Patients' sleeping patterns showed the most rapid and dramatic response, with 59% of evaluated patients improved after one week and 90% after six weeks of maprotiline. Anxiety decreased in 57% of patients after one week and in 81% after six weeks. Depression was reduced in 46% of evaluated patients after one week and in 86% after six weeks. Forty-one percent of patients exhibited more drive after one week of maprotiline and 78% did so after six weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of oxaprotiline enantiomers given repeatedly on the behavioural effects of d-amphetamine and dopamine injected into the nucleus accumbens.

The effects of (+)- and (-)-oxaprotiline, given repeatedly (10 mg/kg p.o., twice daily, 14 days), on the behavioural action of d-amphetamine and dopamine injected bilaterally into the nucleus accumbens were studied in rats. Repeated but not acute treatment with (+)- or (-)-oxaprotiline enhanced the d-amphetamine-induced locomotor hyperactivity. Both enantiomers, given repeatedly but not acutely, attenuated the inhibition of exploration activity induced by dopamine and potentiated the stimulating effect of dopamine as assessed in the open field test. The results indicate that, like other antidepressants studied previously, both oxaprotilines increase the responsiveness of the dopamine mesolimbic system (nucleus accumbens) of the rat.

Differential effects of K(ATP) channel blockers on [(3)H]-noradrenaline overflow after short- and long-term exposure to (+)-oxaprotiline or desipramine.

To test whether prolonged uptake blockade can lead to changes in the function of ATP-dependent potassium (K(ATP)) channels we investigated in rat neocortex slices the effects of K(ATP) channel blockers on electrically evoked [(3)H]-noradrenaline ([(3)H]-NA) overflow after short- (45 min) and long-term (210 min) exposure to the NA uptake blockers (+)-oxaprotiline or desipramine (1 microM each). The K(ATP) channel blocker glibenclamide (1 micro M) increased the evoked [(3)H]-NA overflow by 42% after short-term uptake inhibition. This effect was confirmed by tolbutamide and glipizide, two other K(ATP) channel antagonists. The evoked [(3)H]-NA overflow was enhanced by 73% following short-term uptake blockade (15 min) and by 110% following long-term blockade (180 min). After long-term blockade (210 min), however, glibenclamide failed to further enhance the overflow of [(3)H]-NA. The alpha(2)-autoreceptor-mediated feedback control was not involved in the glibenclamide-induced increase in [(3)H]-NA overflow after short-term uptake blockade or in the increase in [(3)H]-NA overflow due to long-term uptake blockade per se. The Na(+)/K(+)-ATPase inhibitor ouabain diminished the glibenclamide-induced enhancement of [(3)H]-NA overflow after short-term uptake blockade, suggesting that an operative Na(+)/K(+)-ATPase is the prerequisite of activation of K(ATP) channels. These results suggest that short-term uptake blockade activates the Na(+)/K(+)-ATPase, thereby reducing intracellular ATP which allows transient opening of K(ATP) channels. Activation of the Na(+)/K(+)-ATPase may increase the Na(+) gradient, probably over the membrane of noradrenergic nerve terminals. The resulting hyperpolarisation leads to inhibition of the evoked overflow which can be reversed, i.e. enhanced, by K(ATP) channel blockers. In contrast, longer lasting uptake blockade seems to reduce the activity of the Na(+)/K(+)-ATPase and hence the consumption of ATP. As a consequence, reduced Na(+) and K(+) gradients may facilitate transmitter release. Closure of K(ATP) channels by accumulating ATP may further promote membrane depolarisation and transmitter release. The unexpected effect of longer exposure to uptake blockers could be somehow related to the clinical time latency of the antidepressant efficacy of monoamine uptake blockers.

Chemistry, pharmacology, pharmacokinetics, adverse effects, and efficacy of the antidepressant maprotiline hydrochloride.

Maprotiline, a tetracyclic antidepressant with sedative properties, exhibits strong inhibitory effects on norepinephrine uptake across nerve cell membranes but interferes relatively little with serotoninergic mechanisms. The biological half-life of unchanged maprotiline in blood averages 43 hours. Though several studies suggest a more rapid onset of antidepressant effects with maprotiline than with amitriptyline or imipramine, this issue remains unresolved. The adverse effect profile of maprotiline is similar to that of the tricyclic antidepressants, except that rashes are about twice as frequent with maprotiline as with amitriptyline or imipramine. The most frequent adverse reactions are anticholinergic effects and sedation. Data suggest less frequent and severe anticholinergic side effects with maprotiline than with amitriptyline. Maprotiline may be less likely to induce orthostatic hypotension and tachycardia than standard tricyclic antidepressants, but clinically important differences in cardiovascular effects remain to be conclusively demonstrated. Many patients benefit from the convenience of once daily dosing. Maprotiline is comparable in antidepressant efficacy to the tricyclic antidepressants.

Brofaromine versus lithium addition to maprotiline. A double-blind study in maprotiline refractory depressed outpatients.

Depressed outpatients (n = 51) resistant to treatment with maprotiline were treated in a blind, randomized, single-centre study, for 6 weeks with either the reversible and selective monoamine oxidase A-inhibitor (MAO-A-I), brofaromine or lithium addition to maprotiline. The Hamilton Rating Scale for Depression was scored by an independent rater before and after the 6 week treatment period. No significant differences in efficacy were found between the two treatment regimes. In the patients who completed the trial, brofaromine was well tolerated with the exception of insomnia. Anticholinergic effects as well as thyroid dysfunctions (17 out of 20) were more frequent in the maprotiline/lithium group.

Predictors of (non-) response in depressed outpatients treated with a three-phase sequential medication strategy.

The predictive value of eight domains or sets of variables including sociodemographic aspects, premorbid history, symptomatology, personality, social and diagnostic data are evaluated in depressed outpatients with a Hamilton Rating Scale for Depression (HRSD) score of at least 14. Patients were treated using a three-phase sequential treatment strategy. Of the 119 patients, 88 completed the trial. The HRSD-score at the end of phases I, II or III was used as an outcome measure. Patients with an initially high HRSD-score and an obsessive-compulsive personality had a greater chance of recovery, while patients with somatization and a passive-aggressive personality had less of a chance of recovery. Variables involving psychiatric history, premorbid history or symptomatology of the depression, were not significantly related to outcome. The endogenous/non-endogenous distinction was not a predictor of response.