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At least 19 recordsLinked to original sources

PubMed1994

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.

Adolescent↗

PubMed1991

Pharmacokinetics of maprotiline and its demethylated metabolite in serum and specific brain regions of rats after acute and chronic administration of maprotiline.

The concentrations of maprotiline (MAP) and its demethylated metabolite desmethylmaprotiline (DMAP) in the serum and specific brain regions were determined periodically after acute or chronic administration of 20 mg/kg of MAP in rats. MAP was eliminated in a biexponential manner from the serum and monoexponentially from the brain. The DMAP declined monoexponentially from the serum and brain regions. No significant difference was observed in elimination among the eight brain regions examined. In the brain, MAP distributed unevenly after chronic administration, whereas DMAP showed an even distribution. In the acute administration, the AUCbrain: AUCserum ratio of MAP was similar to that of DMAP, and the AUCDMAP: AUCMAP ratio in the serum was almost equal to that in the brain, indicating equivalent ability of MAP and DMAP to penetrate into the brain. After chronic administration, the AUCDMAP value in the serum increased 4.1 times, whereas no marked change was observed for MAP. There was no evidence of enhanced N-demethylation activity from in vitro metabolism study, suggesting that the enhanced AUCDMAP value was not attributable to the enhancement of drug metabolizing activity. Although the AUCMAP value in the brain, as well as in the serum, increased slightly, the AUCDMAP in the brain increased 2.3 times, showing less increase than that in the serum. These findings suggest inhibited distribution of DMAP into tissue, including brain regions, after chronic administration. The pharmacokinetics of the demethylated metabolite DMAP is affected more than that of MAP by chronic administration of MAP.

Animals↗

PubMed1992

Pharmacokinetic analysis of maprotiline and its demethylated metabolite in serum and brain of rats after acute and chronic oral administration of maprotiline.

Compartmental model analysis by simultaneous curve fitting was used to ascertain the pharmacokinetic relationship between maprotiline (MAP) and its demethylated metabolite desmethylmaprotiline (DMAP) in the serum and brain of rats after single or multiple oral administrations of MAP. The extent of bioavailability and the fraction metabolized to DMAP after acute oral administration were 0.202 and 0.065, respectively, indicating first-pass metabolism of MAP. Although the estimated transfer rate constants to and from the brain (k(in) and k(out)) of MAP were higher than those of DMAP, the k(in):k(out) ratio for MAP was similar to that for DMAP. These findings indicate the equivalent ability of MAP and DMAP to penetrate into the brain after acute oral administration. The estimated values of bioavailability and fraction metabolized to DMAP increased 2.6 and 1.7 times, respectively, after chronic administration of MAP. These findings are attributable to inhibited distribution in tissue. The k(in) and k(out) values of MAP decreased, whereas those of DMAP showed no marked change. Therefore, the k(in):k(out) ratio for MAP decreased, whereas that for DMAP did not change. These results suggest that the permeability of MAP into the brain might be affected and that of DMAP is not modified by chronic administration of MAP.

Administration, Oral↗

PubMed2004

Effect of the antidepressant maprotiline on Ca2+ movement and proliferation in human prostate cancer cells.

1. The effect of maprotiline, an antidepressant, on human prostate cells is unclear. In the present study, the effect of maprotiline on [Ca2+]i and growth in PC3 human prostate cancer cells was measured using the fluorescent dyes fura-2 and tetrazolium, respectively. 2. Maprotiline caused a rapid, concentration-dependent increase in [Ca2+]i (EC50 = 200 micromol/L). The maprotiline-induced [Ca2+]i increase was reduced by removal of extracellular Ca2+ or pretreatment with nicardipine. 3. The maprotiline-induced Mn2+ influx-associated fura-2 fluorescence quench directly suggests that maprotiline caused Ca2+ influx. 4. In Ca(2+)-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca(2+)-ATPase, caused a monophasic [Ca2+]i increase, after which the effects of maprotiline of increasing [Ca2+]i were abolished. In addition, pretreatment with maprotiline reduced a major portion of the thapsigargin-induced increase in [Ca2+]i. 5. U73122, an inhibitor of phospholipase C, abolished the ATP (but not maprotiline)-induced increase in [Ca2+]i. 6. Overnight incubation with 1-10 micromol/L maprotiline did not alter cell proliferation, although incubation with 30-50 micromol/L maprotiline decreased cell proliferation. 7, These findings suggest that maprotiline rapidly increases [Ca2+]i in human prostate cancer cells by stimulating both extracellular Ca2+ influx and intracellular Ca2+ release and that it may modulate cell proliferation in a concentration-dependent manner.

Antidepressive Agents, Second-Generation↗

PubMed2004

Effect of the antidepressant maprotiline on calcium movement and the viability of renal tubular cells.

In Madin-Darby canine kidney (MDCK) cells, the effect of maprotiline, an antidepressant, on intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured using fura-2. Maprotiline (> 2.5 microM) caused a rapid rise of [Ca(2+)](i) in a concentration-dependent manner (EC(50) 200 microM). Maprotiline-induced [Ca(2+)](i) rise was reduced by removal of extracellular Ca(2+) or by addition of La(3+), but was not altered by voltage-gated Ca(2+)-channel blockers. Maprotiline-induced Mn(2+) influx-associated fura-2 fluorescence quench directly suggests that maprotiline caused Ca(2+) influx. In Ca(2+)-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca(2+)-ATPase, caused a monophasic [Ca(2+)](i) rise, after which the increasing effect of maprotiline on [Ca(2+)](i) was nearly abolished; also, pretreatment with maprotiline reduced a portion of thapsigargin-induced [Ca(2+)](i) rise. U73122, an inhibitor of phospholipase C, abolished [Ca(2+)](i) rise induced by ATP (but not by maprotiline). Overnight incubation with 1-10 microM maprotiline enhanced cell viability, but 20-50 microM maprotiline decreased it. These findings suggest that maprotiline rapidly increases [Ca(2+)](i) in renal tubular cells by stimulating both extracellular Ca(2+) influx and intracellular Ca(2+) release, and may modulate cell proliferation in a concentration-dependent manner.

Animals↗

PubMed2006

Atypical tetracyclic antidepressant maprotiline is an antagonist at cardiac hERG potassium channels.

Maprotiline is an antidepressant compound with an atypical tetracyclic structure that is widely used in elderly patients due to its favourable side-effect profile. However, there have been reports of proarrhythmia associated with maprotiline and in vitro studies of its electrophysiological properties have been lacking. Therefore, we characterised the effects of maprotiline on cardiac hERG channels. hERG channels were expressed in HEK cells and in the Xenopus oocyte expression system. Currents were measured using a whole-cell patch clamp and a two-microelectrode voltage-clamp. Maprotiline inhibited hERG currents with an IC(50) of 8.2 micromol/l in HEK cells and 29.2 micromol/l in Xenopus oocytes. Onset of the effect was rather slow and took several minutes. No wash-out of effect was observed. Maprotiline blocked hERG channels in the open and inactivated states, but not in the closed states. In mutant hERG channels Y652A and F656A, the effect was markedly attenuated (hERG-F656A) or completely abolished (hERG-Y652A). Voltage dependence of hERG current activation and inactivation was not affected by maprotiline. hERG inactivation was accelerated at positive potentials. The effect of maprotiline on hERG currents was voltage-dependent with a marked reduction at a more positive potential. hERG blockade by maprotiline was not frequency-dependent. Maprotiline is an antagonist of cardiac hERG potassium channels that preferably accesses the putative pore binding site Y652/F656. Although the affinity of maprotiline to hERG channels is low, its use in patients with risk factors for acquired long QT syndrome should be monitored appropriately.

Animals↗

PubMed1997

A comparison a amitriptyline and maprotiline in the treatment of painful polyneuropathy in diabetics and nondiabetics.

OBJECTIVE: To compare amitriptyline and maprotiline in the treatment of painful polyneuropathy in diabetics and nondiabetics. DESIGN: A double-blind, crossover trial of treatment with amitriptyline, maprotiline, and placebo. Treatment was given in randomized order for periods of 4 weeks. Each period was separated by a 1-week washout. The final dose was 75 mg/day for both amitriptyline and maprotiline. PATIENTS: Thirty-seven patients with diabetic and nondiabetic painful polyneuropathy. OUTCOME MEASURES: The treatment effects were assessed by daily ratings of pain intensity on a 10-step verbal scale (0 = no pain and 10 = worst thinkable pain) and at the end of each treatment period by a global rating of the analgesic effect on a 5-step verbal scale (pain relief scale). For the assessment of depression, the Comprehensive Psychopathological Rating Scale (CPRS) was used. RESULTS: Using the global assessment of pain relief at the end of each treatment period, 22 of 33 patients reported reduced pain on amitriptyline treatment compared with 14 of 33 patients on maprotiline treatment and 8 patients on placebo treatment (p < .0001 and p < .05 for amitriptyline and maprotiline, respectively, against placebo). Amitriptyline was slightly better than maprotiline (p < .05) [tested by repeated measures analysis of variance (ANOVA)]. The order in which treatments occurred and the diagnosis of diabetes or nondiabetes did not have any significant effect on the global rating of pain relief. The mean values of the daily ratings of pain intensity showed that pain was more severe in the evenings than in the mornings and that diabetic patients reported worse pain than nondiabetics at baseline. The mean values of pain reduction as assessed with the 10-step verbal scale during the 4th week of treatment showed that amitriptyline and maprotiline were significantly better than placebo in relieving the pain (p < .0001 and p < .01, respectively, post hoc test according to Scheffé). However, there was no significant difference between the pain reduction of amitriptyline compared with maprotiline when assessing pain reduction with the 10-step verbal scale during the 4th treatment week. Nor was there a significant difference between diabetics and nondiabetics with regard to the effect of the drugs. The clinical effect was not significantly correlated to plasma concentration of either amitriptyline and its active metabolite nortriptyline or maprotiline in the global or daily assessments. The effect of treatment was not correlated to any particular pain quality nor to the intensity of pain. Depression was noted in three patients who completed the medication trial, but the effect of treatment of pain and depression did not clearly correlate. The adverse side effects of amitriptyline and maprotiline were common, and in 5 patients the medication had to be discontinued because of severe side effects. CONCLUSION: From the present results and the literature, it is concluded that tricyclic antidepressants with a pharmacologic profile similar to amitriptyline are the most effective drugs in the treatment of polyneuropathy pain in both diabetic and nondiabetic patients.

Adult↗

PubMed1990

Response to total sleep deprivation before and during treatment with fluvoxamine or maprotiline in patients with major depression--results of a double-blind study.

To test the hypothesis that the antidepressant effects of total sleep deprivation (TSD) are linked to the serotonergic and/or noradrenergic system the authors carried out a double-blind study (fluvoxamine versus maprotiline) in 42 inpatients with endogenous depression (ICD). Patients were randomized to a four-week treatment with either fluvoxamine (100-300 mg/day) or maprotiline (100-300 mg/day). In addition, patients underwent a TSD procedure before and after one week of antidepressant medication. There was a statistically significant reduction of depression ratings (HDRS) in both the fluvoxamine and maprotiline group. The day-1 response to TSD before antidepressive medication was not associated with a clear relationship to the outcome after four weeks of treatment with either fluvoxamine or maprotiline. On the other hand, the day-2 response to TSD was significantly correlated with a good outcome to subchronic treatment with maprotiline. Furthermore, the results of the authors' data suggest that a favorable short-term outcome of TSD may be connected to antidepressants enhancing the serotonergic neurotransmission. The global comparison between fluvoxamine and maprotiline revealed that the group of patients treated with fluvoxamine had a significantly higher efficiency index (CGI) than the maprotiline group; fluvoxamine was rated to be tolerated excellently in 70% of the patients whereas this percentage was only 43% in the maprotiline group. There was also significantly more vertigo and dry mouth in the maprotiline group whereas the fluvoxamine group was rated to have significantly more sleep disturbances during the trial.

Adult↗

PubMed1975

[Behavior pharmacology of maprotiline, a new antidepressant].

The effect of maprotiline (N-methyl-9, 10-ethanoanthracene-9 (10H)-propylamine) on animal behavior was investigated in mice and rats and compared with those of amitriptyline and imipramine. Maprotiline inhibited reserpine hypothermia in mice and tetrabenazine ptosis in rats, while it potentiated the effects of methamphetamine, L-DOPA and apomorphine in mice, in a similar manner to that of amitriptyline and imipramine. Maprotiline was more potent than anitriptyline and imipramine in antagonizing haloperidol-induced catalepsy as well as in suppressing muricide induced by either olfactory bulbectomy or delta-9-tetrahydrocannabinol in rats. Maprotiline potentiated anesthesia induced by thiopental or ether in mice to a lesser degree than did amitriptyline, and failed to counteract the lethal effect of physostigmine or oxotremorine tremor in mice, indicating that this drug has no central anti-cholinergic effect. Maprotiline markedly inhibited hyperemotionality of the rat with either septal lesions or olfactory bulb ablations, suggesting that it does have a tranquilizing effect. Inhibition of conditioned avoidance response of the rat in the shuttle box and reduction of methamphetamine group toxicity with maprotiline were similar to those with amitriptyline. Maprotiline exaggerated pentetrazol convulsion, decreased muscle tone and impaired coordinated motor activity in mice to a much lesser degree than amitriptyline and imipramine. LD50 of maprotiline was approximately twice that of imipramine and three times that of amitriptyline. These results indicate that maprotiline is a new type of antidepressant, has a low toxicity and shares both potent antidepressant and some tranquilizing effect, without possessing central anticholinergic action.

Aggression↗

PubMedDate not supplied

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.

Anthracenes↗

PubMed1980

GLC-mass spectrometric determination of maprotiline and its major metabolite using stable isotope-labeled analog as internal standard.

A quantitative GLC-mass spectrometric assay was developed for the determination of maprotiline and its major metabolite, desmethylmaprotiline, in animal and human plasma. The assay utilizes selective-ion focusing to monitor, in a GLC effluent, the fragment ions and the base peaks of maprotiline and desmethylmaprotiline trifluoroacetamides generated by electron-impact ionization. Maprotiline-d3 was the internal standard. The assay can measure 2 ng of maprotiline (and the metabolite)/ml of plasma with approximately 5% precision. The curves relating the amounts of maprotiline and the metabolite added versus the amounts experimentally found over a large concentration range were linear with nearly zero intercepts and slopes of 0.99 +/- 0.01 and 0.98 +/- 0.02, respectively. The method was used to study the pharmacokinetic pattern of the drug in rabbits as well as to analyze intact maprotiline and the metabolite in patients maintained on therapeutic doses of maprotiline. Assay specificity was confirmed by complete consistency of the mass spectra of maprotiline and desmethylmaprotiline with those of the authentic materials.

Animals↗

PubMed1983

Relative acute cardiovascular toxicity induced by maprotiline, mianserin and nomifensine in conscious rabbits.

The relative acute cardiovascular toxicity among three novel antidepressants: maprotiline, mianserin and nomifensine, has been assessed in conscious rabbits ip injected at 50 mg/kg, throughout a 150 min observation period. No death was observed in mianserin rabbits (n = 6), but 3 in the maprotiline rabbits (n = 8) and 1 death in the nomifensine group (n = 8), within the 2 hours. Cardiac output and renal blood flow were determined by the radioactive Sephadex microspheres method. Cardiac output values were significantly lowered (-29%) at 120 min only in mianserin rabbits, whereas renal blood flow values were reduced by 46.8% (mianserin, 35.8% (maprotiline) and 28% (nomifensine) at 120 min. In mianserin and maprotiline rabbits left ventricular pressure and mean arterial pressure fell significantly, but remained unchanged in nomifensine group. ECG disturbances consisting of ventricular and supraventricular extrasystoles were seen in all the injected rabbits, but QRS widening and right bundle branch block were solely observed after maprotiline and mianserin. Nomifensine rabbits experienced severe seizures with hypocapnia and metabolic acidosis. The drug myocardial/plasma ratio ranged between 59.3 (maprotiline) 13.25 (mianserin) and 0.92 (nomifensine). A rise in plasma catecholamines (epinephrine) was documented after mianserin but not after nomifensin and maprotiline. Nomifensine exhibited much lesser cardiotoxicity than mianserin and maprotiline at this dose (50 mg/kg), but induced more convulsions.

Animals↗

PubMed1983

Lack of interaction between the tetracyclic antidepressant maprotiline and the centrally acting antihypertensive drug clonidine.

The well known interaction between tricyclic antidepressants and the centrally acting antihypertensive drug clonidine, namely impairment of the antihypertensive effect of clonidine, is thought to be related to blockade of noradrenaline uptake or competition at central alpha-receptors. The tetracyclic antidepressant maprotiline has been shown to be a potent inhibitor of noradrenaline uptake and it might, therefore, interfere with the antihypertensive action of clonidine. The possible interaction of clonidine and maprotiline was studied in 8 healthy subjects using doses in the therapeutic range. The study followed a double-blind, cross over design, in which clonidine alone (0.3 mg p.o.), clonidine (0.3 mg p.o.) plus maprotiline (100 mg in 4 divided doses over 22 h), maprotiline alone (100 mg in 4 divided doses over 22 h) and placebo were given by the double-dummy technique. Several pharmacodynamic parameters were measured for 12 h after administration of the drugs (supine and erect blood pressure, heart rate, saliva production and sedation). Concurrent administration of maprotiline did not alter the effect of clonidine and neither the size nor the time of the maximal response after clonidine were influenced by maprotiline. It is concluded that [1] blockade of noradrenaline uptake is not associated with the interaction of tricyclic antidepressants and clonidine, and [2] maprotiline should be preferred to tricyclic antidepressants in hypertensive patients on clonidine therapy if a concomitant depressive illness has to be treated.

Adult↗

PubMed1997

Non-response to maprotiline caused by ultra-rapid metabolism that is different from CYP2D6?

CASE: We are reporting about a patient with major depression who failed to respond to pharmacotherapy due to ultra-rapid metabolism of maprotiline. Under daily oral doses of 175 mg maprotiline, the patient's metabolic ratio (MR) for maprotiline in plasma was 9.2 (expected MRp: 2.4) and the clearance of maprotiline (CLM) was 4190 ml.min-1 (expected CLM = 1220 in extensive metabolisers of CYP2D6). RESULTS: The patient's MRurine for sparteine was 0.5, which is within the range for extensive metabolisers of CYP2D6. Genotyping did not show a duplication of the CYP2D6L allele. The patient's caffeine half-life was 10 h, thus, precluding ultra-rapid metabolism for CYP1A2. The therapeutic regiment was changed to co-administration of 200 mg maprotiline and 20 mg fluoxetine once per day in order to inhibit metabolism via CYP2D6. Subsequently, MRP of maprotiline (4.9) and CLM were reduced (1900 ml.min-1; expected CLM in poor metabolisers: of CYP2D6 364). This regimen improved the clinical outcome of the underlying disease. CONCLUSION: We conclude that for the non-response seen with maprotiline, P450 isozymes other than CYP2D6 or CYP1A2 are responsible. As CYP2C19 is involved in the metabolism of a number of tricyclic antidepressants it may be a candidate for ultra-rapid metabolism in this patient.

Alleles↗

PubMed2004

Effect of maprotiline on Ca(2+) movement in human neuroblastoma cells.

In human neuroblastoma IMR32 cells, the effect of the anti-depressant maprotiline on baseline intracellular Ca2+ concentrations ([Ca2+]i) was explored by using the Ca2+-sensitive probe fura-2. Maprotiline at concentrations greater than 100 microM caused a rapid rise in [Ca2+]i in a concentration-dependent manner (EC50 = 200 microM). Maprotiline-induced [Ca2+]i rise was reduced by 50% by removal of extracellular Ca2+. Maprotiline-induced [Ca2+]i rises were inhibited by half by nifedipine, but was unaffected by verapamil or diiltiazem. In Ca2+-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca2+-ATPase, caused a monophasic [Ca2+]i rise, after which the increasing effect of maprotiline on [Ca2+]i was abolished. U73122, an inhibitor of phospholipase C, did not affect maprotiline-induced [Ca2+]i rises. These findings suggest that in human neuroblastoma cells, maprotiline increases [Ca2+]i by stimulating extracellular Ca2+ influx and also by causing intracellular Ca2+ release from the endoplasmic reticulum via a phospholiase C-independent manner.

Biological Transport, Active↗

PubMedDate not supplied

Current perception thresholds of patients with long-term administration of maprotiline.

The purpose of this study was to evaluate sensory nerve function using current perception thresholds (CPTs) in patients who were administrated maprotiline. Twelve patients with post-herpetic neuralgia and 20 control subjects were studied. The patients with post-herpetic neuralgia were given a daily dose of 60 mg of maprotiline and were maintained at the same dose for 6 months. Twenty control subjects were randomly selected from healthy volunteers. ACPT test was used for quantitative assessment of A beta, A sigma, and C fiber transmission, which are associated with pain, by three (2000, 250, and 5 Hz) different frequencies of electric stimulation. CPTs of 5, 250, and 2000 Hz in patients with post-herpetic neuralgia 2 months after administration of maprotiline were 141.7 +/- 17.3 for 5 Hz, 120.8 +/- 12.9 for 250 Hz, and 256.4 +/- 18.0 for 2000 Hz, which were significantly (P < 0.01) higher than those (67.0 +/- 9.1 for 5 Hz, 73.4 +/- 7.0 for 250 Hz, and 191.3 +/- 20.2 for 2000 Hz) before treatment and than those (35.3 +/- 15.8, 62.0 +/- 18.9, and 198.9 +/- 15.8) of control subjects. An increase in CPT for 5 Hz at 2 months after administration of maprotiline correlated (r = 0.71, p = 0.01) with a decrease in pain score. There were no correlations between an increase in CPT and changes in Hamilton Depression Scale (HAMD) values until 3 months after maprotiline treatment. However, we found that an increase in CPT for 5 Hz at 6 months after maprotiline treatment correlated (r = 0.68, p = 0.015) with a decrease in HAMD values. In conclusion, administration of 60 mg maprotiline significantly increased current perception thresholds at 2 months after the administration.

Adrenergic Uptake Inhibitors↗

PubMed1979

The relative toxicity of amitriptyline, imipramine, maprotiline and mianserin in rabbits in vivo.

1. Conscious or barbiturate-anaesthetized rabbits were slowly infused intravenously with solutions of amitriptyline, imipramine, maprotiline or mianserin, usually until death occurred. 2. Amitriptyline produced death at the lowest dose, imipramine and maprotiline were intermediate while much higher doses of mianserin were required. 3. Convulsions were induced by the antidepressants in all conscious rabbits and the order of potency of the drugs in producing this effect was amitriptyline greater than or equal to imipramine greater than maprotiline greater than mianserin. 4. All four drugs produced a reduction in heart rate and blood pressure in the anaesthetized rabbits and the order of potency in this respect was amitriptyline greater than imipramine greater than maprotiline greater than mianserin. 5. All four drugs produced significant changes in the ECG compared with control rabbits. The P-R interval was lengthened (potency order amitriptyline greater than imipramine greater than or equal to maprotiline greater than mianserin) and the QRS complex was widened (potency order amitriptyline greater than imipramine greater than or equal to maprotiline greater than mianserin). 7. It is concluded that all four drugs show the toxic effects classically associated with tricyclic antidepressants but the relative toxicity amongst these agents varies considerably and is in the order amitriptyline greater than imipramine greater than maprotiline greater than mianserin.

Amitriptyline↗

PubMed1975

Pharmacological studies of drug action on CNS, with special reference to effects of maprotiline.

The effects of maprotiline, mainly on the CNS, were examined and compared with those of imipramine, methamphetamine and chlorpromazine. In the repeated administration and the stroboscope studies, maprotiline exhibited actions to increase behavioral activities of animals, just like amphetamine and imipramine. This appears to attest to pharmacological effects of maprotiline as an anti-depressant. It is noted, however, that whereas maprotiline shows a slight anti-apomorphine action in dogs and an inhibition of the spinal reflex action potential in cats, such actions are not recognized in other anti-depressants of the tricyclic groups including imipramine, amitriptyline, etc. These differences suggest the tranquilizing action of maprotiline at work, probably forming a specific pharmacological feature of maprotiline. Also, maprotiline increases body weight of rats strikingly, which seems to offer a wide range of clinical applications of this drug.

Action Potentials↗