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Nefazodone and imipramine in major depression: a placebo-controlled trial.

Nefazodone is a phenylpiperazine antidepressant with 5-HT2 antagonism and 5-HT reuptake inhibition. Two hundred and eighty-three out-patients with a diagnosis of DSM-III-R major depression of at least one-month duration (65% ill for over 6 months), and a mean score of 24 on the 17-item Hamilton Rating Scale for Depression (HRSD), were randomised to treatment with nefazodone, imipramine, or placebo. The double-blind treatment period was 8 weeks in duration. Nefazodone's antidepressant efficacy was comparable with imipramine's, with both drug treatments significantly better than placebo in a variety of outcome measures. For example, after 8 weeks of therapy, 78% of nefazodone and 83% of imipramine but only 55% of placebo patients (P < 0.01) were globally much or very much improved. Nefazodone was better tolerated than imipramine, with fewer drop-outs and a lower incidence of side-effects during treatment.

Adult↗

Different effects of amitriptyline and imipramine on the pharmacokinetics and metabolism of perazine in rats.

The aim of this study was to search for possible effects of imipramine and amitriptyline on the pharmacokinetics and metabolism of perazine at steady state in rats. Perazine (10 mg kg(-1), i.p.) was administered to rats twice daily for two weeks, alone or jointly with imipramine or amitriptyline (10 mg kg(-1) i.p.). Concentrations of perazine and its two main metabolites (5-sulphoxide and N-desmethylperazine) in the plasma and brain were measured at 30 min (Cmax), 6h and 12h (slow disposition phase) after the last dose of the drugs. Liver microsomes were prepared 24 h after withdrawal of the drugs. Amitriptyline increased the plasma and brain concentrations of perazine (up to 300% of the control) and N-desmethylperazine, while not affecting those of 5-sulphoxide. Imipramine only tended to increase the neuroleptic concentration in the plasma and brain. Studies with control liver microsomes showed that amitriptyline and imipramine added to the incubation mixture in-vitro, competitively inhibited N-demethylation (Ki (inhibition constant) = 16 microM and 164 microM, respectively) and 5-sulphoxidation (Ki = 57 microM and 86 microM, respectively) of perazine, amitriptyline being a more potent inhibitor of perazine metabolism, especially with respect to N-demethylation. Studies with microsomes of rats treated chronically with perazine or tricyclic antidepressants, or both, did not show significant differences in the rate of perazine metabolism between perazine- and perazine+antidepressant-treated rats. The data obtained were compared with the results of analogous experiments with promazine and thioridazine. It was concluded that elevations of perazine concentration were caused by direct inhibition of the neuroleptic metabolism by the antidepressants. Similar interactions, possibly leading to exacerbation of the pharmacological action of perazine, may be expected in man. Since the interactions between phenothiazines and tricyclic antidepressants may proceed in two directions, reduced doses of both the neuroleptic and the antidepressant are recommended when the drugs are administered jointly.

Amitriptyline↗

Imipramine-serotonin induced myopathy.

Imipramine and serotonin (5-HT) were used to produce a myopathy in rats. Imipramine was used to stimulate a defect in transport of 5-HT observed in the platelets of Duchenne's dystrophy patients. The most effective dosage schedule was imipramine, 10 mg per kilogram, for 7 days followed by 5-HT, 100 mg per kilogram, 6 hours after the final imipramine dose. A single series of injections produced focal groups of necrotic and regenerating muscle fibers. In some rats, multiple series of injections resulted in a chronic myopathy with a predilection for proximal muscles, particularly quadriceps. In addition to skeletal muscle lesions, focal areas of myocardial damage were seen. The affected rats had a marked elevation of plasma creatine phosphokinase (including MB isoenzyme), serum glutamic oxaloacetic transaminase, and lactic dehydrogenase. Femoral nerve section did not affect the development of muscle lesions.

Animals↗

Effects of chlorpromazine, imipramine and baclofen on the spinal polysynaptic reflex in acute, chronic and 6-hydroxydopamine-treated spinal rats.

Effects of the drugs affecting monoaminergic neurotransmission were examined on the spinal polysynaptic reflex (PSR) in anesthetized spinal rats. Chlorpromazine HCI (0.5-2.0 mg/kg, i.v.) and baclofen (0.63-2.5 mg/kg) depressed and imipramine HCI (1.25-5.0 mg/kg) increased the amplitude of PSR in acute spinal animals, recorded as evoked electromyogram in the gastrocnemius muscle by electrical stimulation of the common peroneal nerve. However, chlorpromazine and imipramine showed effects neither on PSR in chronic spinal rats, nor in acute spinal rats with the intracisternal administration of 6-hydroxydopamine, which caused depletion of the spinal noradrenaline, dopamine and serotonin, and selective depletion of the spinal noradrenaline, respectively. Baclofen depressed the amplitude of PSR in both preparations with almost the same potency as that in acute spinal ones. Imipramine HCI (2.5 mg/kg, i.v.), chlorpromazine HCI (1.0 mg/kg) and baclofen (1.25 mg/kg) depressed the mono- and polysynaptic heights of the ventral root potentials in acute spinal rats. However, their depression of polysynaptic height was not so strong. These observations strongly suggest that, at the receptor sites on spinal interneurons where the descending monoaminergic neurons terminate, spinal monoamines, especially noradrenaline, are involved in PSR modification by chlorpromazine and imipramine, but not in PSR depression by baclofen.

Animals↗

Chronic effects of imipramine and lithium on postsynaptic 5-HT1A and 5-HT1B sites and on presynaptic 5-HT3 sites in rat brain.

The effects of chronic treatment with imipramine, a tricyclic antidepressant, or lithium, an antimanic-depressive illness drug, on postsynaptic serotonin-1A (5-HT1A) and 5-HT1B sites and on presynaptic 5-HT3 sites in the frontal cortex and hippocampus from rat brains were studied. Chronic i.p. administration (21 days) of imipramine reduced the maximum number of binding sites (Bmax) for postsynaptic 5-HT1A as monitored by the radioligands 3H-5-HT or 3H-8-hydroxy-2-(di-n-propylamino)tetralin (3H-8-OH-DPAT), but did not change the Bmax for postsynaptic 5-HT1B and presynaptic 5-HT3 in either the frontal cortex or the hippocampus. Chronic i.p. administration (21 days) of lithium reduced the Bmax for postsynaptic 5-HT1A sites in the hippocampus, but not in the frontal cortex. There was a specific difference between imipramine and lithium regarding the inhibitory effect on postsynaptic 5-HT1A sites in the frontal cortex. In addition, lithium decreased the affinity of presynaptic 5-HT3 sites in the hippocampus. These findings may be also consistent with the inhibitory effect of lithium on presynaptic autoreceptors, which results in an increase of 5-HT release. It is concluded that enhanced 5-HT neurotransmission which develops during chronic treatment with imipramine or lithium seems tob e related to the down-regulation of postsynaptic 5-HT1A receptors in addition to postsynaptic 5-HT2 receptors, which may also have an important role in the antidepressant effects of these drugs.

Animals↗

Effects of imipramine, an uptake inhibitor, on double-peaked constrictor responses to periarterial nerve stimulation in isolated, perfused canine splenic arteries.

Using a cannula insertion method, periarterial nerve electrical stimulations were performed at 1 and 10 Hz in the isolated, perfused canine splenic artery. Electrical nerve stimulation readily caused double-peaked vasoconstrictions. The 1st-peak response at 1 Hz was not influenced by treatment with imipramine but the 2nd one was significantly enhanced by it. The 2nd-peak response was markedly blocked by prazosin. An additional treatment with alpha,beta-methylene ATP, a P2X-purinoceptor desensitizer, abolished electrical stimulation-induced vascular responses that remained. At 10 Hz, the responses to electrical stimulation were not significantly influenced by imipramine. On the other hand, the imipramine treatment inhibited the tyramine-induced vasoconstriction but potentiated the noradrenaline-induced one. ATP-induced responses were not modified by imipramine. From these results, it is concluded that 1) the 1st-peaked constriction is mainly due to a P2X-purinoceptor-dependent mechanism, 2) the 2nd one is mainly due to an alpha1-adrenoceptor-dependent mechanism, and 3) presynaptic uptake mechanisms may perform an important role in the regulation of vascular reactivity, especially at a low frequency.

Adenosine Triphosphate↗

Chronic treatment with imipramine inhibits cell growth and enhances serotonin 2C receptor mRNA expression in NG 108-15 cells.

We previously reported that NG108-15 cells contain intrinsic serotonin 2C receptor (5-HT2CR). The effects of imipramine, a 5-HT2CR antagonist, on cell growth, cell viability, and the 5-HT2CR mRNA level were investigated in this study. Repeated treatment with imipramine at concentrations of 1 - 10 microM for 5 days inhibited cell growth in a concentration-dependent manner without affecting cell viability. In addition, the level of 5-HT2CR mRNA was elevated. At 30 microM, imipramine significantly reduced cell viability. Our findings suggest that the effect of imipramine on neuronal growth may be related to its effects on 5-HT2CR.

Animals↗

In vivo and in vitro effect of imipramine and fluoxetine on Na+,K+-ATPase activity in synaptic plasma membranes from the cerebral cortex of rats.

The effects of in vivo chronic treatment and in vitro addition of imipramine, a tricyclic antidepressant, or fluoxetine, a selective serotonin reuptake inhibitor, on the cortical membrane-bound Na+,K+-ATPase activity were studied. Adult Wistar rats received daily intraperitoneal injections of 10 mg/kg of imipramine or fluoxetine for 14 days. Twelve hours after the last injection rats were decapitated and synaptic plasma membranes (SPM) from cerebral cortex were prepared to determine Na+,K+-ATPase activity. There was a significant decrease (10%) in enzyme activity after imipramine but fluoxetine treatment caused a significant increase (27%) in Na+,K+-ATPase activity compared to control (P<0.05, ANOVA; N = 7 for each group). When assayed in vitro, the addition of both drugs to SPM of naive rats caused a dose-dependent decrease in enzyme activity, with the maximal inhibition (60-80%) occurring at 0.5 mM. We suggest that a) imipramine might decrease Na+,K+-ATPase activity by altering membrane fluidity, as previously proposed, and b) stimulation of this enzyme might contribute to the therapeutic efficacy of fluoxetine, since brain Na+,K+-ATPase activity is decreased in bipolar patients.

Animals↗

Antidepressant efficacy of sertraline and imipramine for the treatment of major depression in elderly outpatients.

CONTEXT: Most double-blind studies of efficacy and tolerability of sertraline as compared to tricyclics in the treatment of late-life major depression have used amitriptyline as a standard, leading to the inevitable conclusion that the former drug is better tolerated than the latter, with both being equally efficacious. OBJECTIVE: To compare the antidepressant efficacy and tolerability of sertraline (50 mg/day) and imipramine (150 mg/day) in the first 6 weeks of the treatment of major depression in the elderly. DESIGN: A randomized double-blind parallel study with 6 weeks of follow-up. SETTING: The psychogeriatric clinic at the Institute of Psychiatry, Hospital das Clínicas, Faculty of Medicine of the University of São Paulo. PARTICIPANTS: 55 severe and moderately depressed non-demented outpatients aged 60 years or more. INTERVENTION: Patients were assigned to sertraline 50 mg/day or imipramine 150 mg/day. MAIN MEASUREMENTS: CAMDEX interview. Psychiatric diagnosis followed the guidelines for "Major Depressive Episode" according to DSM-IV criteria. Severity of symptoms was evaluated using the "CGI" and "MADRS" scales. Cognitive state was assessed using the Mini-Mental State Examination. Side effects were assessed using the "Safetee-Up" schedule. RESULTS: Both groups had a significant decrease in depressive symptoms according to the MADRS scores after 6 weeks of treatment (P = 0.01). No significant differences between groups were detected regarding treatment outcome (t = 0.4; P = 0.7). Although the dropout rate was greater in the imipramine group, the overall tolerability among patients who completed the 6-week trial was similar in both test groups. CONCLUSIONS: Both sertraline and imipramine exhibited good efficacy and an acceptable side-effect profile for elderly depressed patients after 6 weeks of antidepressant treatment.

Aged↗

Cost analysis of paroxetine versus imipramine in major depression.

A simulation decision analytical model was used to compare the annual direct medical costs of treating patients with major depression using the selective serotonin reuptake inhibitor (SSRI) paroxetine or the tricyclic antidepressant (TCA) imipramine. Medical treatment patterns were determined from focus groups of general and family practitioners and psychiatrists in Boston, Dallas and Chicago, US. Direct medical costs included the wholesale drug acquisition costs (based on a 6-month course of drug therapy), psychiatrist and/or general practitioner visits, hospital outpatient visits, hospitalisation and electroconvulsive therapy. Acute phase treatment failure rates were derived from an intention-to-treat analysis of a previously published trial of paroxetine, imipramine and placebo in patients with major depression. Maintenance phase relapse rates were obtained from a 12-month trial of paroxetine, supplemented from the medical literature. The relapse rates for the final 6 months of the year were obtained from medical literature and expert opinion. Direct medical costs were estimated from a health insurance claims database. The estimated total direct medical cost per patient was slightly lower using paroxetine ($US2348) than generic imipramine ($US2448) as first-line therapy. This result was sensitive to short term dropout rates but robust to changes in other major parameters, including hospitalisation costs and relapse rates. The financial benefit of paroxetine, despite its 15-fold higher acquisition cost compared with imipramine, is attributable to a higher rate of completion of the initial course of therapy and consequent reduced hospitalisation rates.

Antidepressive Agents, Second-Generation↗

Beneficial effects of imipramine on Tourette's syndrome.

Gilles de la Tourette's syndrome (GTS) is a chronic neuropsychiatric disorder characterized by multiple involuntary motor and phonic tics associated with behavioural disturbances including obsessive-compulsive and aggressive behavior, depression and, rarely, psychosis. The relationship of GTS, presumed to be predominantly a dopaminergic disorder, and depression, presumed to be a noradrenergic-serotoninergic deficiency state, is currently poorly understood. The reports published to date on the effects of tricyclic antidepressants in GTS have been contradictory; while Messiha et al. (1976) used imipramine successfully in one GTS patient, Abuzzahab and Anderson (1973) and Fras (1978) on the other hand, found imipramine to exacerbate GTS symptoms and cautioned its usage in this syndrome. A more recent report suggested that imipramine is useful in GTS patients who exhibit symptoms of attention deficit disorder (Dillon et al., 1985). We report a patient with GTS whose depression and behaviour improved considerably when low-dose imipramine (Tofranil) was added to the regimen of anti-GTS medication. This report suggest that tricyclic antidepressants may be useful adjuncts in the management of GTS, and hints at norepinephrinergic and serotoninergic deficiencies as being components of the pathogenesis of the syndrome.

Child↗

The influence of an experimental liver cirrhosis upon the metabolism of diazepam and imipramine hydrochloride in the rat.

When either diazepam or imipramine hydrochloride was administered orally to rats with thioacetamide-induced hepatic cirrhosis, the biliary and faecal elimination of metabolites was significantly decreased compared with that in normal animals. However, renal excretion of metabolites of diazepam or imipramine was increased in the liver-damaged rats. Experiments in vitro showed that liver homogenates from cirrhotic rats metabolized diazepam or imipramine hydrochloride in qualitatively and quantitatively similar ways to those from normal rats. Clearance of radioactivity from the blood following i.v. administration of either diazepam or imipramine hydrochloride was prolonged in animals with experimental cirrhosis.

Animals↗

Pre- and postsynaptic localization of 3H-imipramine binding sites in rat cerebral cortex.

The subcellular localization of 3H-imipramine binding sites in brain was investigated with the aim of learning about the possible mechanism of action of this antidepressant. The rat cerebral cortex was submitted to a systematic fractionation and both the nuclear and the synaptosomal fractions were purified by gradient centrifugation. Using a centrifugation assay for the binding, we found that the synaptosomal membranes had the highest specific activity and showed two binding sites, one of high affinity with a KD of 14 nM and a Bmax of 3.1 pmol per mg protein, and another of lower affinity with a KD of 99 nM and a Bmax of 14.2 pmol per mg protein. Purified nuclei have a lower specific activity than the synaptosomal membrane, specially when expressed per g tissue. On the other hand, myelin and capillaries have few binding sites. Synaptosomal membranes were treated with 0.1, 0.2 and 0.5% Triton X-100 to dissolve the pre- and post-synaptic membrane and submitted to 3H-imipramine binding in the presence of the detergent or after washing of the residue. The results obtained suggest that although most 3H-imipramine binding sites are localized pre-synaptically, a certain proportion are post-synaptic. These findings are discussed in relation to previous studies from this laboratory on the localization of central receptors with reference to the synaptic region and to the antidepressant action of imipramine.

Animals↗

The treatment of chronic depression, part 2: a double-blind, randomized trial of sertraline and imipramine.

BACKGROUND: Chronic depression appears to be a common, frequently disabling illness that is often inadequately treated. Unlike episodic depressions with shorter illness duration, neither acute nor long-term treatment approaches for chronic depression have been well studied. METHOD: 635 outpatients at 12 sites who met DSM-III-R criteria for chronic major depression or double depression were randomly assigned to 12 weeks of double-blind treatment with either sertraline (in daily doses of 50-200 mg) or imipramine (in daily doses of 50-300 mg). Efficacy and safety were assessed either weekly or every 2 weeks during the 12 weeks of acute treatment. RESULTS: Despite high rates of chronicity (mean duration of major depression = 8.9+/-9.1 years; mean duration of dysthymia = 23+/-13 years) and high rates of comorbidity, 52% of patients achieved a satisfactory therapeutic response to sertraline or imipramine (by a conservative, intent-to-treat analysis). Approximately 21% of the patients who had achieved a therapeutic response at week 12 had not done so at week 8, confirming the longer time to response in depressions with high chronicity. Patients treated with sertraline reported significantly fewer adverse events and were significantly less likely to discontinue treatment due to side effects than imipramine-treated patients (6.3% vs. 12.0%). CONCLUSION: These results indicate that patients suffering from depression with high chronicity can achieve a good therapeutic response to acute treatment with either sertraline or imipramine, although sertraline is better tolerated.

Adult↗

Suppressive effect of TRH and imipramine on human interferon-gamma and interleukin-10 production in vitro.

It has been established that thyrotropin-releasing hormone (TRH) affects several aspects of immunoreactivity, e.g. production of pro-inflammatory cytokines, and enhances therapeutic efficiency of classic tricyclic antidepressants. On the other hand, it has been suggested that pro-inflammatory cytokines play a role in the etiology of depression, whereas the therapeutic efficacy of antidepressants is related to their negative immunoregulatory effect. In order to verify the hypothesis that the TRH-induced increase in the therapeutic efficiency of classic tricyclic antidepressants results from synergistic inhibitory effects of those two agents on the secretion of pro-inflammatory cytokines, we studied the effect of imipramine appliedjointly with TRH on the production of IFN-gamma and IL-10 by human whole blood cells stimulated in vitro by mitogens. A significant decrease in the production of IFN-gamma and IL-10 cytokines, by 36% and 34%, respectively, was observed in cells stimulated with mitogens and co-incubated with imipramine and TRH (either given at a dose of 10(-5) M). Under the same conditions, TRH alone did not change the production of those cytokines. Furthermore, imipramine alone decreased, not statistically significantly, though, the production of IFN-gamma. Hence our data only partly support the above-mentioned hypothesis, since TRH and imipramine applied jointly suppress the production of both the pro-inflammatory IFN-gamma and the anti-inflammatory IL-10 cytokines.

Adult↗

Actions of the antidepressant drug imipramine on the voltage-clamped Myxicola giant axon.

The effects of the antidepressant drug imipramine were studied on the voltage-clamped Myxicola giant axon at concentrations from 10- minus 6 to 5 X 10- minus 5 M. Over this range, imipramine reversibly reduced both the sodium and potassium conductances without having any substantial effect on either the resting membrane potential or the leakage conductance. The observed dose-response relation is described by a Langmuir adsorption isotherm with an apparent dissociation constant of 9 X 10-minus 6 M. The sodium and potassium conductance-voltage curves are shifted in the hyperpolarizing direction along the voltage axis, the magnitude of the displacement increasing with increasing concentrations of imipramine. There was no significant effect of imipramine on either time to peak sodium current or time to half-maximum steady-state current.

Animals↗

Relative bioavailability of imipramine (Tofranil) coated tablets in healthy volunteers.

OBJECTIVES: Imipramine is a tricyclic antidepressant drug with a considerable hepatic first-pass metabolism resulting in highly variable pharmacokinetic characteristics and desipramine as active major metabolite. This study describes the bioavailability of 3 formulations of imipramine. METHODS: In a randomized, three-period crossover study, 18 healthy male Caucasian subjects received single oral doses of Tofranil 25, Tofranil mite (10 mg) and an aqueous solution containing 25 mg imipramine-HCl. Serum concentrations of imipramine-HCl and its main metabolite desipramine were measured. The pharmacokinetic characteristics, Cmax, AUC, t1/2 and tmax were determined and the relative bioavailability of the two coated tablet formulations was calculated with the aqueous solution as reference. Safety and tolerability were assessed using vital signs, ECG, clinical laboratory and adverse event recording. RESULTS: The relative bioavailabilities of Tofranil 25 and Tofranil mite were 97% and 81%, respectively. The study medication was well tolerated. CONCLUSIONS: A sufficiently high extent of absorption was found for the test formulations ensuring therapeutic efficacy.

Administration, Oral↗

Lack of a modulatory effect of imipramine on glucocorticoid-induced suppression of interferon-gamma and interleukin-10 production in vitro.

Antidepressant drugs have been shown to reverse some changes evoked by glucocorticoids or stress. In the present study we attempted to find out whether imipramine, one of the most frequently used antidepressant drugs, interfered with glucocorticoids, modulating the production of IFN-gamma and IL-10, pro-inflammatory and anti-inflammatory cytokines, respectively. We observed a significant inhibitory effect of hydrocortisone, dexamethasone and the glucocorticoid receptor agonist RU 28362, used at doses of 10(-6) and 10(-5) M, on the production of IFN-gamma and IL-10 by whole blood cells stimulated by mitogens. Imipramine at doses of 10(-6) and 10(-5) M did not modulate IFN-gamma or IL-10 production, whereas at a dose of 10(-5) M it increased the production of IL- 10 and decreased that of IFN-gamma, those results being statistically insignificant, though. A combination of imipramine and dexamethasone or hydrocortisone at doses of 10(-6) or 10(-5) M significantly suppressed the production of IFN-gamma and IL-10, the level of inhibition being similar to that observed for glucocorticoids alone. The classic antidepressant imipramine was not able to modulate the suppressive effect of "stress" doses of hydrocortisone on the production of cytokines.

Adult↗