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PubMed1989

[Effect of trazodone (KB-831) and its metabolites on brain monoamines in rat].

The effects of trazodone (KB-831) and its metabolites on the uptake, turnover and contents of monoamines in rats were studied in comparison with those of imipramine and mianserin. Trazodone exhibited a more potent inhibitory effect on the uptake of [3H] 5-hydroxytryptamine (5-HT) into brain synaptosomes than on the uptake of [3H]norepinephrine (NE). Trazodone at 10-30 mg/kg, p.o., also inhibited the p-chloramphetamine-induced depletion of 5-HT in rat brain, but not the 6-hydroxydopamine-induced NE depletion in rat heart. Trazodone was the most selective 5-HT uptake inhibitor among the drugs tested in vitro. Its metabolite, m-chlorophenyl-piperazine (m-CPP), inhibited 5-HT and NE uptake in vitro, but not in vivo. Trazodone (100 mg/kg) and imipramine (30-100 mg/kg) inhibited the depletion of NE induced by alpha-methyl-p-tyrosine, whereas mianserin (100 mg/kg) facilitated it. At 1 hr after a single administration of each drug, an increase in 5-HT content and a decrease in 5-hydroxyindole-3-acetic acid (5-HIAA) content were observed when 30 mg/kg trazodone was used. At 100 mg/kg, trazodone increased the levels of dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) and decreased the NE content. m-CPP (10-30 mg/kg) produced similar effects on monoamine contents to those of trazodone. Imipramine and mianserin had no effect on monoamine contents even at a dose of 100 mg/kg. After 3 weeks of successive administration, an increase in 5-HT and a decrease in 5-HIAA were induced by trazodone and m-CPP at 1 hr, but not at 17 hr, after the final administration. Imipramine decreased the contents of NE and 5-HIAA, and its effects lasted for 17 hr. These results suggest that trazodone is a selective 5-HT uptake inhibitor and that its neurochemical profile is different from those of imipramine and mianserin.

Animals↗
PubMed2000

Increased rate of trazodone prescribing with bupropion and selective serotonin-reuptake inhibitors versus tricyclic antidepressants.

OBJECTIVE: To determine whether trazodone is prescribed significantly more often with selective serotonin-reuptake inhibitors (SSRIs) and bupropion than with tricyclic antidepressants (TCAs). METHODS: A retrospective analysis of Iowa City Department of Veteran's Affairs prescription records from March 1, 1995, to March 1, 1998, was performed. Antidepressants prescribed only by psychiatrists were included. Concomitant use was defined as trazodone prescribed on the same date or up to 42 days after the fill date of the primary antidepressant. STATISTICS: All comparisons used 2 x 2 chi 2 contingency table. Significance level was set at p < 0.05. RESULTS: Significantly more patients were prescribed trazodone concurrently with bupropion and SSRI antidepressants than with TCAs. Trazodone was prescribed significantly more often for patients receiving an SSRI (p = 0.0001, chi 2 = 14.59) or bupropion (p = 0.0295, chi 2 = 4.74) than for patients receiving a TCA. There was no significant difference in trazodone use between the patients taking SSRIs or bupropion. The percent of patients that received an SSRI, bupropion, or a TCA in combination with trazodone was 27%, 23%, and 13%, respectively. Overall, 23.7% of patients received trazodone concomitantly with a primary antidepressant. DISCUSSION: The effects of antidepressants on sleep and on sleep scores of depression rating scales are reviewed. The clinical implications of these findings are discussed. The literature addressing the effects of antidepressants on sleep and on sleep scores of depression rating scales is summarized. Although sleep studies suggest that SSRIs may not improve sleep as well as a TCA, clinical studies do not often support these findings. Several studies report that bupropion may not improve sleep parameters as well as doxepin or trazodone. The clinical implications of these findings are discussed. CONCLUSIONS: We have demonstrated that our clinicians prescribe trazodone at a significantly higher rate with an SSRI or bupropion than with a TCA. The exact reason for this difference is not known. If trazodone is used during the first six weeks of an initial antidepressant treatment trial, it should be discontinued to determine whether the patient's sleep disturbance has responded to the primary antidepressant. More comparison studies among the newer antidepressants and between classes of antidepressants concerning their effects on sleep in the depressed patient need to be performed.

Antidepressive Agents, Tricyclic↗
PubMed1983

Effects of acute and chronic trazodone administration on serum prolactin levels in adult female rats.

Trazodone was tested for its ability to elevate serum prolactin levels in mature female rats. When the drug was administered acutely to female rats at doses up to 80 mg/kg ip, it induced a clear rise in serum prolactin levels, with a minimum effective dose of 20 mg/kg; blood trazodone levels at these doses were between 1.6-2.4 micrograms/ml. However, trazodone could not be considered to be a potent stimulator of prolactin secretion, since the injection of haloperidol at 2 mg/kg elevated serum prolactin to values twice those seen in animals receiving the 80 mg/kg dose of trazodone. When trazodone was administered chronically in the diet for two or four weeks, at an average daily dose of 80 mg/kg, serum trazodone levels were found to be 100-200 ng/ml when measured at each stage of the estrous cycle. Serum prolactin levels in trazodone-treated animals, however, did not differ from those in control rats. Moreover, drug-treated animals showed normal proestrus surges in serum prolactin. The results of these studies thus indicate that acutely, at very high doses, trazodone probably can stimulate prolactin secretion modestly in female rats. However, when consumed chronically at 80 mg/kg/day, the drug has no effects on serum prolactin levels. Therefore, if trazodone stimulates prolactin secretion by altering neurotransmission across dopamine and/or serotonin synapses in brain, it is probably not potent in these actions, at least as concerns those dopamine and serotonin neurons that influence the secretion of prolactin.

Animals↗
PubMed1984

Interactions of trazodone with serotonin neurons and receptors.

Trazodone, 2-[3-[4-(m-chlorophenyl)-1-piperazinyl]propyl]-s- triazolo[4,3-a]pyridin-3(2H)one, was evaluated as an inhibitor of uptake into serotonin neurons in vivo in the brains of mice and rats by determining its ability to antagonize the depletion of brain serotonin by p-chloroamphetamine. In mice, trazodone was inactive under conditions in which many antidepressant drugs and other inhibitors of uptake are potent antagonists of the depletion of serotonin in brain induced by p-chloroamphetamine. Weak inhibition of uptake into serotonin-containing neurons in brain in vivo was demonstrated early after the injection of trazodone in rats, especially when the dose of p-chloroamphetamine was reduced to facilitate competitive inhibition of its effects. However, the effects of trazodone were short-lasting. Trazodone did not potentiate the elevation of serum corticosterone by L-5-hydroxytryptophan, in contrast to the effect of fluoxetine, a potent and selective inhibitor of the uptake of serotonin. Instead, trazodone antagonized a response mediated by a serotonin receptor, i.e. elevation of serum corticosterone by a serotonin agonist, quipazine, in rats. Trazodone also antagonized the serotonin-induced contraction of the rat jugular vein in vitro (a response mediated by 5-HT2 receptors), the pA2 being 8.79. These findings agree with previous reports that trazodone is a potent antagonist of serotonergic function. These data, together with earlier evidence, suggest it is unlikely that the inhibition of uptake of serotonin contributes to the clinical antidepressant effects of trazodone.

5-Hydroxytryptophan↗
PubMed1985

The role of trazodone metabolism in its inhibitory action on avoidance response.

To assess the role of trazodone metabolism in its depressant action on conditioned avoidance response we investigated whether in the mouse brain 3-chlorophenylpiperazine (CPP) is formed from trazodone, whether trazodone metabolism is affected by a drug metabolism inhibitor, proadifen, and how trazodone, CPP and their combinations act on avoidance responses in proadifen-pretreated mice. It was found that CPP is formed from trazodone in mice, that proadifen inhibits trazodone metabolism, and that the moderate and transient inhibitory effect of trazodone on avoidance responses is dramatically potentiated and prolonged in proadifen-pretreated mice. This effect, and inhibition of unconditioned escape response observed in mice receiving lower doses of trazodone after proadifen pretreatment, were counteracted by CPP. The results indicate that the inhibitory action of trazodone on avoidance response is caused by the parent compound, and that it is brief and moderate because of the rapid metabolism of the drug with formation of CPP which counteracts the depressant effect of the parent compound.

Animals↗
PubMed2005

Metabolic activation of the nontricyclic antidepressant trazodone to electrophilic quinone-imine and epoxide intermediates in human liver microsomes and recombinant P4503A4.

Therapy with the antidepressant trazodone has been associated with several cases of idiosyncratic hepatotoxicity. While the mechanism of hepatotoxicity remains unknown, it is possible that reactive metabolites of trazodone play a causative role. Studies were initiated to determine whether trazodone undergoes bioactivation in human liver microsomes to electrophilic intermediates. LC/MS/MS analysis of incubations containing trazodone and NADPH-supplemented microsomes or recombinant P4503A4 in the presence of glutathione revealed the formation of conjugates derived from the addition of the sulfydryl nucleophile to mono-hydroxylated- and hydrated-trazodone metabolites. Product ion spectra suggested that mono-hydroxylation and sulfydryl conjugation occurred on the 3-chlorophenyl-ring, whereas hydration and subsequent sulfydryl conjugation had occurred on the triazolopyridinone ring system. These findings are consistent with bioactivation sequences involving: (1) aromatic hydroxylation of the 3-chlorophenyl-ring in trazodone followed by the two-electron oxidation of this metabolite to a reactive quinone-imine intermediate, which reacts with glutathione in a 1,4-Michael fashion and (2) oxidation of the pyridinone ring to an electrophilic epoxide, ring opening of which, by glutathione or water generates the corresponding hydrated-trazodone-thiol conjugate or the stable diol metabolite, respectively. The pathway involving trazodone bioactivation to the quinone-imine has also been observed with many para-hydroxyanilines including the structurally related antidepressant nefazodone. It is proposed that the quinone-imine and/or the epoxide intermediate(s) may represent a rate-limiting step in the initiation of trazodone-mediated hepatotoxicity.

Antidepressive Agents, Second-Generation↗
PubMed1995

Oral trazodone as empirical therapy for erectile dysfunction: a retrospective review.

OBJECTIVES: Anecdotal reports of increased libido and sexual function in patients taking trazodone have led to its empirical use in patients with erectile dysfunction. A retrospective review of patient-reported responses to trazodone was performed to outline the efficacy and side-effect profile of this agent. METHODS: Between 1989 and 1994, 182 patients were placed on oral trazodone as empirical therapy for erectile dysfunction. Patients ranged in age from 26 to 85 years, with a mean of 60 years. Patients were evaluated before receiving trazodone with a thorough medical history and physical examination. Known risk factors for erectile dysfunction were assigned based on historical information and the findings of the examination. Patients received trazodone for at least 2 consecutive months, with daily doses starting at 25 mg. RESULTS: One hundred twenty-seven patients were available for follow-up by a standardized questionnaire regarding perceived improvement in erectile function, sexual function, and side effects. In patients less than 60 years of age, with no known risk factors for erectile dysfunction, 21 of 27 (78%) showed significant improvement in erectile ability. Smokers and patients older than 60 years with a history of significant peripheral vascular disease responded poorly to trazodone therapy. The duration of erectile dysfunction was inversely related to a response to trazodone. Of patients with a duration of impotence less than 12 months, 48% reported a positive response. Only 16% of patients with duration of erectile dysfunction greater than 60 months reported improvement in erections and sexual function. Trazodone was well tolerated by this population, with 62% reporting no side effects. CONCLUSIONS: Despite the limitations of a nonrandomized, retrospective study, trazodone appears to benefit younger patients with erectile dysfunction with few known risk factors. A prospective, placebo-controlled trial is needed to confirm the observations of this pilot study.

Administration, Oral↗
PubMed1996

A possible clonidine-trazodone-dextroamphetamine interaction in a 12-year-old boy.

A 12-year-old boy on a dextroamphetamine-clonidine-trazodone treatment regimen had a recurrence of insomnia, and his bedtime trazodone dose was doubled from 50 mg to 100 mg. Within 45 mins after taking the first 100-mg trazodone dose on an empty stomach, the patient had a syncopal episode associated with hypotension, bradycardia, and sedation. The drug reaction could have resulted from either trazodone or clonidine, but it is more likely to have resulted from a pharmacodynamic clonidine-trazodone interaction, presumably aggravated by rapid absorption (on an empty stomach) of a recently increased dose of trazodone. It is conceivable but less likely that the psychostimulant was a clinically significant factor. However, a drug interaction between clonidine and D-amphetamine does not need to be postulated to explain this child's syncopal reaction. The authors advise that (1) if trazodone and clonidine are used concurrently, the doses of both agents should be changed slowly, (2) blood pressure and pulse should be carefully monitored at baseline and then periodically during treatment, and (3) administration of trazodone on an empty stomach, and especially dose increases on an empty stomach, should be avoided. Physicians should remain aware that trazodone has the potential to produce hypotension and sedation, especially when combined with other agents (such as clonidine) that might produce the same adverse effects.

Antihypertensive Agents↗
PubMed1997

Trazodone is only slightly faster than fluoxetine in relieving insomnia in adolescents with depressive disorders.

This retrospective chart review examined the relative effectiveness of fluoxetine and trazodone in relieving insomnia associated with depressive disorders in adolescents (aged 13-17 years). We reviewed the hospital charts of consecutively admitted adolescents with a depressive disorder and insomnia, who received one of three treatments: fluoxetine (20 +/- 2.2 mg), trazodone (71 +/- 32 mg), or a fluoxetine-trazodone combination (fluoxetine 29 +/- 2.2 mg, trazodone 68 +/- 29 mg). Each treatment was examined in 20 patients. Insomnia was defined as a change in sleep patterns characterized by decreased total sleep time that was sufficient to cause clinical concern, and insomnia resolution was defined as sleep starting by midnight and lasting 6 hours. Mean time to resolution of insomnia was significantly faster in adolescents treated with trazodone rather than fluoxetine (2.5 vs. 5.1 days, p < 0.05). Trazodone seemed to save only about 3 days and insomnia resolved in all subjects by the 11th day of antidepressant treatment. Median time to insomnia resolution was 2 days (range 1-5 days) in the trazodone group and 4 days (range 1-11 days) in the fluoxetine group. This difference between trazodone and fluoxetine, although statistically significant, was generally not clinically significant in the management of insomnia associated with depressive disorders in adolescents. The resolution of insomnia was not faster for treatment with a combination of fluoxetine and trazodone in comparison to fluoxetine monotherapy. Insomnia resolution was slightly later in older children. These clinical findings await confirmation by a controlled study. Both drugs seemed effective in ameliorating sleep symptoms in this sample, although it is likely that they produced these changes by different mechanisms.

Adolescent↗
PubMed1997

Effects of trazodone and fluoxetine in the treatment of major depression: therapeutic pharmacokinetic and pharmacodynamic interactions through formation of meta-chlorophenylpiperazine.

It has been suggested that (1) the clinical efficacy of the heterocyclic antidepressant trazodone in depression may, in part, be attributed to its metabolite meta-chlorophenylpiperazine (mCPP); and (2) the enhancement of the efficacy of trazodone by the addition of fluoxetine, a selective serotonin reuptake inhibitor, may, in part, be ascribed to fluoxetine-induced plasma concentrations of trazodone. After a washout period of 10 days, 27 inpatients with major depression were treated with trazodone 100 mg/day (orally). One week later (T0), fluoxetine 20 mg/day, placebo, or pindolol 7.5 mg/day was added. Plasma concentrations of mCPP and trazodone were determined at T0 and 2 and 4 weeks later. Although placebo pindolol had no significant effect on the plasma concentrations of mCPP and trazodone, there was a significant increase of the concentrations of these compounds associated with the combination of trazodone + fluoxetine. The results suggest that fluoxetine-induced increases in plasma mCPP and trazodone concentrations contribute to the clinical efficacy of the combination of fluoxetine + trazodone. It is suggested that desensitization of 5-HT2C receptor function by mCPP as well as fluoxetine may contribute to the antidepressant effects of this combination.

Adult↗
PubMed1982

Trazodone (Desyrel, Mead-Johnson Pharmaceutical Division).

Trazodone is the first triazolopyridine derivative to be used clinically for the treatment of depression. It has been shown to be equal in efficacy to the tricyclic antidepressants imipramine, desipramine, and amitriptyline in the treatment of major depressive episodes. Researchers have indicated that trazodone exceeds other antidepressants in relieving anxiety, but further study is needed to confirm this effect. Trazodone has been used successfully to relieve depression in schizophrenic patients without worsening their psychotic symptoms. Trazodone blocks serotonin reuptake into presynaptic neurons with little effect on norepinephrine or dopamine. It is rapidly absorbed orally and reaches peak serum levels within two hours. Trazodone is excreted primarily as metabolites by the kidneys and possesses a biphasic elimination half-life of 4.4 hours for the first 10 hours and 7.5 hours for the next 24 hours. Trazodone 200 mg is equal to imipramine 100 mg, and the therapeutic dosage range is 200-600 mg/d. Side effects are infrequent with trazodone; its anticholinergic activity is minimal. Trazodone appears to produce less cardiovascular toxicity than tricyclic antidepressants. To date, reports of fatal overdoses are rare. Trazodone equals available antidepressant drugs in clinical efficacy, and, because it has fewer cardiovascular and anticholinergic side effects, it should prove beneficial in the treatment of depression.

Animals↗
PubMed2006

A comparative, randomized, double-blind study of trazodone prolonged-release and sertraline in the treatment of major depressive disorder.

OBJECTIVES: To evaluate the efficacy and safety of trazodone prolonged-release compared with sertraline in the treatment of patients with major depression. RESEARCH DESIGN AND METHODS: A total of 122 patients aged 19-64 years were enrolled in this multicenter, double-blind, double-dummy, randomized, comparator-controlled study. Patients received 7 days of single-blind placebo treatment followed by 6 weeks of double-blind treatment with trazodone prolonged-release 150-450 mg/day (n = 62) or sertraline 50-100 mg/day (n = 60). OUTCOME MEASURES: Efficacy was evaluated by mean changes from baseline in the Hamilton Depression Rating scale (HAM-D), Montgomery Asberg Depression Rating Scale, Hamilton Anxiety Rating scale, and the Clinical Global Impression-Global Improvement/Severity scores; and by the rates of patients responding to treatment and considered to be in remission. Time to onset of efficacy and safety were assessed. RESULTS: Trazodone and sertraline were equally effective in reducing depressive symptoms and promoting remission, and had similar onset times. In the Intent-to-Treat population, there were no significant differences in favor of trazodone at study endpoint in all efficacy measures, while a statistically significant difference was detected in the Per-Protocol population on HAM-D and in the percentage of responders. Analysis of HAM-D factors (anxiety/somatization, cognitive disturbance, retardation, and sleep disturbance) indicated that sleep disturbances were significantly less evident for patients taking trazodone at study endpoint. Adverse drug reactions, mostly of mild intensity, were reported in 42% of trazodone-treated patients (mainly of the nervous system) and 43% of sertraline-treated patients (mainly gastrointestinal). One event was considered to be serious: a patient treated with trazodone 450 mg/day showed moderate anxiety/tremor/insomnia and was hospitalized. Treatment was discontinued; the patient made a full recovery. CONCLUSIONS: This study showed that after 6 weeks, trazodone and sertraline were not different in reducing symptoms of depression and in producing disease remission. Tolerability profiles reflected the differing pharmacological properties of these antidepressants. Trazodone may be a therapeutic option in the treatment of patients with major depression showing prevalent sleep disturbances.

Adult↗
PubMed2000

Interaction between warfarin and trazodone.

BACKGROUND: It is well known that there are many drug interactions involving warfarin. However, few data have been supplied to guide clinicians concerning the interaction between trazodone and warfarin. CASE SUMMARY: Three clinically significant cases of suspected trazodone and warfarin interactions were identified in a retrospective chart review based on changes in the prothrombin time (PT) and international normalized ratio (INR) that were not explained by other factors. In each of the cases, the INR changed by > or = 1.0 after the initiation or discontinuation of trazodone. In the patients who started trazodone, a subsequent decrease in the PT and INR resulted; conversely, the PT and INR increased in the patient who stopped trazodone therapy. Although none of the patients experienced adverse effects due to the marked changes in PT and INR, the warfarin dosages had to be adjusted accordingly on initiation and discontinuation of trazodone. DISCUSSION: These cases show that there is a potentially clinically significant interaction between trazodone and warfarin. The time to onset of the interaction is variable; the mechanism behind it is not known, but it may involve substrate or protein-binding competition. CONCLUSIONS: The use of trazodone on an as-needed basis for sleep is strongly discouraged in patients who are receiving warfarin, due to the difficulty of achieving a therapeutic PT and INR. Until more is known, patients and clinicians should be educated about this potential interaction and monitor for changes in the anticoagulant effects when trazodone is initiated or stopped.

Aged↗
PubMed2000

Postmortem forensic toxicology of trazodone.

Trazodone is a popular antidepressant medication that has been available for approximately 30 years. It has a reputation as a safe drug with relatively few reported fatalities attributed solely to it. We review the pharmacology and forensic toxicology of trazodone and report toxicology and cause and manner of death in a series of 37 deaths in which trazodone was detected. Although the normal upper therapeutic blood concentration for trazodone is about 2 mg/L, fatalities are rarely attributed solely to it at blood concentrations below 9 mg/L. Considering the pharmacology of the drug, potential interactions between other drugs with serotonin reuptake properties need to be considered, as does the increased susceptibility to the toxic effects in patients with pre-existing heart disease. In the cases reviewed, none were attributed solely to trazodone, although trazodone was frequently present together with other serotonergic drugs, such as the selective serotonin reuptake inhibitors like fluoxetine and sertraline. Ten cases had blood trazodone concentrations above 2 mg/L. Of these cases, trazodone played a primary role in the death of three subjects, with blood concentrations all greater than 9 mg/L. We confirm the conclusions of others that trazodone is a relatively safe drug except in massive overdose, although its toxicity may be influenced by the presence of other drugs and underlying pathophysiology.

Adult↗
PubMed1990

A drug utilization review of prescribing patterns for trazodone versus amitriptyline.

The second-generation antidepressant trazodone has been thought by some clinicians to exert a less robust antidepressant effect than do tricyclic agents. This impression differs from the findings of numerous published clinical trials. In an effort to determine whether this discrepancy may be due to possible inappropriate dosing or use of trazodone for different patient subtypes, a retrospective chart review of 138 depressed inpatients treated with amitriptyline and of 42 depressed inpatients treated with trazodone was performed to compare their respective prescribing patterns. While these two groups did not differ with regard to most demographic variables, results revealed that patient prescribed trazodone were older (trazodone, mean +/- SD age = 54.5 +/- 8.8 years versus amitriptyline, 43.2 +/- 12.9 years; p less than .001), more often had a recurrent depressive disorder (trazodone = 57.1%, amitriptyline = 39.1%, p less than .06), and more frequently had a history of unresponsiveness to other antidepressants (trazodone = 47.6%, amitriptyline = 11.6%; p less than .001). In addition, initially prescribed daily doses of trazodone were below the recommended starting dose of 150 mg/day (mean +/- SD starting dose = 113.7 +/- 42.1 mg/day), while starting daily doses for amitriptyline (mean +/- SD = 69.8 +/- 20.1 mg/day) were judged to be more adequate relative to the recommended daily dose of 75 mg/day. Final trazodone dosage (mean +/- SD final dose = 217.9 +/- 87.5 mg/day) could be judged to have been far short of optimal levels of 250 to 350 mg/day and of up to 600 mg/day for inpatients and 400 mg/day for outpatient.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2004

Inhibition of cardiac HERG potassium channels by the atypical antidepressant trazodone.

Trazodone is an atypical antidepressant that is commonly used in the treatment of affective disorders. There have repeatedly been reports of cardiac arrhythmia associated with this drug and concerns have been raised regarding the cardiac safety of trazodone. However, interaction with HERG channels as a main factor of cardiac side effects has not been studied to date. Therefore, we investigated the effect of trazodone on HERG potassium channels expressed in human embryonic kidney (HEK) cells and in Xenopus oocytes. Trazodone inhibited HERG currents in a dose-dependent manner with an IC50 of 2.9 microM in HEK cells and 13.2 microM in Xenopus oocytes. The electrophysiological properties of HERG blockade were analysed in detail. In HERG channel mutants Y652A and F656A lacking aromatic residues in the S6 domain, the affinity of trazodone was reduced profoundly. Trazodone accelerated inactivation of HERG currents without markedly affecting activation. Blockade was voltage dependent with a small reduction of block at positive membrane potentials. Frequency dependence of block was not observed. Trazodone block of HERG channels was state dependent. Channels were affected in the activated and inactivated states, but not in the closed states. In summary, the atypical antidepressant trazodone blocks cardiac HERG channels at concentrations that are probably relevant in vivo, particularly in overdosage.

Animals↗
PubMed1992

Post-mortem toxico-kinetics of trazodone.

Trazodone is a structurally unique bicyclic anti-depressant, said to be significantly less toxic than other anti-depressants following an acute overdose. We studied the tissue distribution and post-mortem redistribution of trazodone in two fatalities, one of which allowed comparison with trimipramine, a typical tricyclic anti-depressant. Case 1, a 53-year-old female weighing 72 kg, had femoral vein concentrations of trimipramine 5.5 micrograms/ml, trazodone 14.4 micrograms/ml and alcohol 107 mg%. Case 2, a 48-year-old female of 70 kg, had a femoral vein trazodone of 15.5 micrograms/ml and alcohol 34 mg%, with no other drugs detected. For case 1 and case 2 respectively, trazodone tissue concentrations were: skeletal muscle 7.3 and 9.0 micrograms/g; left and right lungs 13.3, 12.9 and 35.3, 40.1; myocardium, 30.9 and 28.9; kidneys 34.7 and 39.6; liver 73.7 and 82.4; fat 18.5 and 16.5; brain 48.6 and 20.9. For case 1 and 2, respectively, blood trazodone concentrations in 10 initial autopsy samples ranged from 13.7-17.3 and 14.4-16.9 micrograms/ml. Twenty-four and forty-eight hours later the respective ranges were 12.8-18.0 and 12.4-19.9 for case 1, 12.5-20.1 and 12.7-27.0 for case 2. By contrast, for trimipramine, blood concentrations at 0 time, 24 h and 48 hours ranged from 5.5-11.4, 5.2-14.3, and 4.2-18.2, respectively. We conclude that trazodone shows little preferential concentration in solid organs and consequently has relatively stable post-mortem blood concentrations with little drug redistribution artefact. Both the clinical pharmacokinetics and post-mortem toxicokinetics of trazodone differ significantly from the tricyclic anti-depressants.

Female↗
PubMed2004

Intracerebroventricular injection of trazodone produces 5-HT receptor subtype mediated anti-nociception at the supraspinal and spinal levels.

Serotonin (5-HT) mediated anti-nociceptive effects induced by an anti-depressant, trazodone, are related to 5-HT(1A) receptor activities at the supraspinal level. 5-HT(3) receptor activation via the descending anti-nociceptive pathways may contribute to the trazodone mediated anti-nociception at the spinal level. Intracerebroventricular (i.c.v.) injection of trazodone dose-dependently impaired nociceptive responses in the formalin test in mice. Six and 15 microg of trazodone inhibited the early (P<0.05 or 0.01) and the late phases of the formalin test (P<0.05 or 0.01), while 3 microg had no effect. We examined the effects of a selective 5-HT(1A) receptor antagonist, WAY-100635, a single injection of which induced hyperalgesia (P<0.05), and blocked the anti-nociceptive effects of trazodone (P<0.01) when the two were simultaneously injected i.c.v. Intrathecal (i.t.) injection of a selective 5-HT(3) receptor antagonist, 3-tropanylindole-3-carboxylate hydrochloride, blocked the anti-nociceptive effects of i.c.v. trazodone (P<0.01), while WAY-100635 (i.t.) did not impair trazodone mediated anti-nociception. Trazodone mediated anti-nocicepton is related to serotonergic activity at both the supraspinal and the spinal level.

Animals↗