Pharmacokinetic and pharmacodynamic characteristics of trazodone in the elderly

Analysis of Factors Affecting Concentrations and Concentration-To-Dose Ratios of Trazodone

BACKGROUND

Trazodone is prescribed for several clinical conditions. Multiple factors may affect trazodone to reach its therapeutic reference range. The concentration-to-dose (C/D) ratio can be used to facilitate the therapeutic drug monitoring of trazodone. The study aimed to investigate factors on the concentrations and C/D ratio of trazodone.

METHODS

This study analyzed the therapeutic drug monitoring electronic case information of inpatients in the First Hospital of Hebei Medical University from October 2021 to July 2023. Factors that could affect the concentrations and C/D ratio of trazodone were analyzed, including body mass index, sex, age, smoking, drinking, drug manufacturers, and concomitant drugs.

RESULTS

A total of 255 patients were analyzed. The mean age was 52.44 years, and 142 (55.69%) were women. The mean dose of trazodone was 115.29 mg. The mean concentration of trazodone was 748.28 ng/mL, which was in the therapeutic reference range (700-1000 ng/mL). 50.20% of patients reached the reference range, and some patients (36.86%) had concentrations below the reference range. The mean C/D ratio of trazodone was 6.76 (ng/mL)/(mg/d). A significant positive correlation was found between daily dose and trazodone concentrations (r 2 = 0.2885, P < 0.001). Trazodone concentrations were significantly affected by dosage, sex, smoking, drinking, and concomitant drugs of duloxetine or fluoxetine. After dosage emendation, besides the above factors, it was influenced by age ( P < 0.05, P < 0.01, or P < 0.001).

CONCLUSIONS

This study identified factors affecting trazodone concentrations and C/D ratio. The results can help clinicians closely monitor patients on trazodone therapy and maintain concentrations within the reference range.

Falls, healthcare resources and costs in older adults with insomnia treated with zolpidem, trazodone, or benzodiazepines

Background

Falls are the leading cause of injury-related death among older Americans. While some research has found that insomnia heightens falls, health care resource utilization (HCRU) and costs, the impact of insomnia treatments on fall risk, mortality, HCRU and costs in the elderly population, which could be of substantial interest to payers, has not been fully elucidated. This study evaluated the risk of falls and related consequences among adults ≥ 65 years of age treated with common prescription medications for insomnia compared with non-sleep disordered controls.

Methods

This was a retrospective cohort analysis of deidentified Medicare claims from January 2011 through December 2017. Medicare beneficiaries treated for insomnia receiving zolpidem extended-release, zolpidem immediate-release, trazodone, or benzodiazepines were matched with non-sleep disordered controls. The main outcomes were falls, mortality, healthcare resource utilization (HCRU), and medical costs during the 12 months following the earliest fill date for the insomnia medication of interest. Generalized linear models controlled for several key covariates, including age, race, sex, geographic region and Charlson Comorbidity Index score.

Results

The study included 1,699,913 Medicare beneficiaries (59.9% female, mean age 75 years). Relative to controls, adjusted analyses showed that beneficiaries receiving insomnia medication experienced over twice as many falls (odds ratio [OR] = 2.34, 95% CI: 2.31–2.36). In adjusted analyses, patients receiving benzodiazepines or trazodone had the greatest risk. Crude all-cause mortality rates were 15-times as high for the insomnia-treated as controls. Compared with controls, beneficiaries receiving insomnia treatment demonstrated higher estimated adjusted mean number of inpatient, outpatient, and emergency department visits and longer length of inpatient stay. All-cause total adjusted mean costs were higher among insomnia treated patients ($967 vs $454).

Conclusions

Individuals receiving insomnia treatment had an increased risk of falls and mortality and higher HCRU and costs compared with matched beneficiaries without sleep disorders. Trazodone and benzodiazepines were associated with the greatest risk of falls. This analysis suggests that significant risks are associated with common, older generation insomnia medication treatments in the elderly. Nonetheless, these results should be interpreted with caution as the use of these medications may be indicative of underlying morbidity with potential for residual confounding.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-03165-6.

Incremental health care resource use and costs among adult patients with depression and treated for insomnia with zolpidem, trazodone, or benzodiazepines

OBJECTIVE

To quantify health care resource utilization (HCRU) and costs associated with insomnia treated with commonly prescribed insomnia medications among patients with depression.

METHODS

A retrospective cohort study was conducted using IBM MarketScan Commercial and Medicare Supplemental Databases to identify adults with: (1) ≥1 ICD-9/ICD-10 code for depression; (2) ≥1 commonly prescribed medication for insomnia (zolpidem immediate release [IR], zolpidem extended release [ER], trazodone, or benzodiazepines); and (3) ≥12 months of eligibility before and after initiating insomnia medication. A 1:1 age- and sex-matched control cohort with depression but without sleep-related disorders was identified. Adjusted HCRU and costs were compared using generalized linear models.

RESULTS

A total of 21,027 patients (mean age = 48.3 years, 69.5% female) with depression and treated insomnia (D + TI; 1.9% zolpidem ER, 32.0% zolpidem IR, 50.0% trazodone, 16.1% benzodiazepines) were matched to controls. Although mean number of inpatient visits were similar (0.1 for both), relative to controls, D + TI had a higher mean number of ED (0.2 vs 0.1, p < .001) and outpatient visits (2.2 vs 1.3, p < .001). Adjusted total costs per patient per month were higher among D + TI patients ($2450 vs $1095, p < .001). Inpatient and ED costs were higher among patients prescribed zolpidem IR, trazodone, or benzodiazepines, but not zolpidem ER.

CONCLUSIONS

Relative to controls with depression but without sleep disorders, overall, health care costs for adults with D + TI were 2.2-fold higher; costs and HCRU varied by insomnia medication. Further study of the impact of newer insomnia treatments on patient outcomes in depression and comorbid insomnia is warranted.

Fall Risk, Healthcare Resource Use, and Costs Among Adult Patients in the United States Treated for Insomnia with Zolpidem, Trazodone, or Benzodiazepines: A Retrospective Cohort Study

INTRODUCTION

Falls are a common cause for morbidity and mortality among patients taking prescription insomnia medication. The objective of this study is to compare the risk of falls, all-cause healthcare resource utilization (HCRU), and costs among patients treated with commonly used, older generation insomnia medications and non-sleep-disordered controls.

METHODS

This retrospective cohort study used the IBM^® MarketScan^® Commercial and Medicare Supplemental Databases to identify patients aged at least 18 years treated with commonly prescribed medications for insomnia (zolpidem, trazodone, benzodiazepines) between 1 January 2012 and 30 September 2017. The insomnia-treated cohort were age- and sex-matched (1:1) to non-sleep-disordered controls. Odds ratios (ORs) compared risk of falls in each cohort, adjusting for covariates. Costs were adjusted to 2018 dollars, the most recent year for the study data.

RESULTS

Relative to matched controls (n = 313,086), the insomnia-treated cohort had a higher rate of falls (3.34% vs. 1.33%), and higher risk of falls [OR = 2.36 (95% confidence interval 2.27-2.44)]. Relative to other index treatments, patients treated with trazodone had the greatest risk of falls. Compared with matched controls, the estimated mean number of inpatient visits, emergency department visits, outpatient visits, and mean length of inpatient stay were all significantly higher among patients treated for insomnia. Such patients incurred greater total costs per patient per month than matched controls ($2100 versus $888; estimated mean ratio, 2.36; 95% CI 2.35-2.38; p < 0.0001).

CONCLUSIONS

Relative to matched controls, the insomnia-treated cohort showed higher risk of falls with greater HCRU and costs. Each outcome measured was highest among patients treated with trazodone, relative to other index treatments. Findings suggest the need for new treatment options to optimize quality of care for patients with insomnia.

Estimation of an Appropriate Dose of Trazodone for Pediatric Insomnia and the Potential for a Trazodone-Atomoxetine Interaction

There is a paucity of clinical trials for the treatment of pediatric insomnia. This study was designed to predict the doses of trazodone to guide dosing in a clinical trial for pediatric insomnia using physiologically‐based pharmacokinetic (PBPK) modeling. Data on the pharmacokinetics of trazodone in children are currently lacking. The interaction potential between trazodone and atomoxetine was also predicted. Doses predicted in the following age groups, with exposures corresponding to adult dosages of 30, 75, and 150 mg once a day (q.d.), respectively, were: (i) 2‐ to 6‐year‐old group, doses of 0.35, 0.8, and 1.6 mg/kg q.d.; (ii) >6‐ to 12‐year‐old group, doses of 0.4, 1.0, and 1.9 mg/kg q.d.; (iii) >12‐ to 17‐year‐old group, doses of 0.4, 1.1, and 2.1 mg/kg q.d. An interaction between trazodone and atomoxetine was predicted to be unlikely. Clinical trials based on the aforementioned predicted dosing are currently in progress, and pharmacokinetic data obtained will enable further refinement of the PBPK models.

Tai Chi exercise for sleep problems in older adults: A protocol of systematic review and meta-analysis

BACKGROUND

Sleep plays a crucial role in the general health of the human body. However, sleep problems become increasingly severe with age, and its incidence is on the rise. Notably, Tai Chi exercise may be an efficacious means to ameliorate sleep problems among older adults. This is especially since Tai Chi has been widely used to manage sleep problems in China for many years, but there is limited evidence regarding its effectiveness. We will conduct this study aiming to investigate the efficacy of Tai Chi as a complementary and alternative therapy for sleep problems in older adults.

METHODS

We will systematically search Scopus, Embase, PubMed, Cochrane Library, China National Knowledge Infrastructure, and Wanfang database from their inceptions to August 2019. Only randomized controlled trials of Tai Chi for sleep problems among older adults will be considered for inclusion and the Pittsburgh sleep quality index will be the primary outcome measurement. Moreover, study selection, data extraction, and the evaluation of the methodological quality of trials will each be independently completed by at least 2 researchers. We will employ the software Stata version 12.0 to implement the statistical analysis.

RESULTS

The current systematic review and meta-analysis will provide synthesized results of the effectiveness and safety of Tai Chi exercise for sleep problems among older adults.

CONCLUSION

This systematic review and meta-analysis will provide high-quality evidence on the effectiveness and safety of Tai Chi exercise for sleep problems in older adults.

REGISTRATION

PEROSPERO CRD42019129782.

Challenges and innovations of drug delivery in older age

Both drug delivery performance and various age-related physical, mental and physiological changes can affect drug effectiveness and safety in elderly patients. The many drug delivery systems developed over the years include recent novel transdermal, nasal, pulmonary and orally disintegrating tablets that provide consistent, precise, timely and more targeted drug delivery. Certain drug delivery systems may be associated with suboptimal outcomes in the elderly because of the nature of drug present, a lack of appreciation of the impact of age-related changes in drug absorption, distribution and clearance, the limited availability of pharmacokinetic, safety and clinical data. Polypharmacy, patient morbidity and poor adherence can also contribute to sub-optimal drug delivery systems outcomes in the elderly. The development of drug delivery systems for the elderly is a poorly realised opportunity, with each system having specific advantages and limitations. A key challenge is to provide the innovation that best meets the specific physiological, psychological and multiple drug requirements of individual elderly patients.

Low-Dose Trazodone, Benzodiazepines, and Fall-Related Injuries in Nursing Homes: A Matched-Cohort Study

OBJECTIVES

To evaluate whether risk of fall-related injuries differs between nursing home (NH) residents newly dispensed low-dose trazodone and those newly dispensed benzodiazepines.

DESIGN

Retrospective, matched cohort study in linked, population-based administrative data. Matching was based on propensity score ( ± 0.2 standard deviations of the score as a caliper), age ( ± 1 year), sex, frailty status, and history of dementia. The derived propensity score included demographic characteristics, clinical comorbidities, cognitive and functional status, and risk factors for falls.

SETTING

All NHs in Ontario, Canada.

PARTICIPANTS

Propensity score-matched pairs of residents aged 66 and older who received a full clinical assessment between April 1, 2010, and March 31, 2015 (N=7,791).

MEASUREMENTS

Hospitalization (emergency department visit or acute care admission) for a fall-related injury within 90 days of exposure. Subdistribution hazard functions accounted for competing risk of death. Sensitivity analyses were used to examine falls resulting in hip or wrist fracture only, as well as different lengths of follow-up at 30, 60, and 180 days.

RESULTS

Cumulative incidence of a fall-related injury in the 90 days after index was 5.7% for low-dose trazodone users and 6.0% for benzodiazepine users (between-group change=-0.29, 95% confidence interval (CI)=-1.02-0.44]; hazard ratio=0.94, 95% CI=0.83-1.08). Findings were consistent across sensitivity analyses.

CONCLUSION

New use of low-dose trazodone was no safer with respect to a risk of a fall-related injury than new use of benzodiazepines. Additional studies to compare the effectiveness and risks of low-dose trazodone with those of a variety of psychotropic drug therapies are required in light of increasing trends in the use of trazodone in NHs.

Prescribing Non-Opioid Drugs in End-Stage Kidney Disease

Therapeutic Reviews aim to provide essential independent information for health professionals about drugs used in palliative and hospice care. Additional content is available on www.palliativedrugs.com. Country-specific books (Hospice and Palliative Care Formulary USA, and Palliative Care Formulary, British and Canadian editions) are also available and can be ordered from www.palliativedrugs.com. The series editors welcome feedback on the articles (hq@palliativedrugs.com).

Age-related changes in antidepressant pharmacokinetics and potential drug-drug interactions: a comparison of evidence-based literature and package insert information

BACKGROUND

Antidepressants are among the most commonly prescribed psychotropic agents for older patients. Little is known about the best source of pharmacotherapy information to consult about key factors necessary to safely prescribe these medications to older patients.

OBJECTIVE

The objective of this study was to synthesize and contrast information in the package insert (PI) with information found in the scientific literature about age-related changes of antidepressants in systemic clearance and potential pharmacokinetic drug-drug interactions (DDIs).

METHODS

A comprehensive search of two databases (MEDLINE and EMBASE from January 1, 1975 to September 30, 2011) with the use of a combination of search terms (antidepressants, pharmacokinetics, and drug interactions) was conducted to identify relevant English language articles. This information was independently reviewed by two researchers and synthesized into tables. These same two researchers examined the most up-to-date PIs for the 26 agents available at the time of the study to abstract quantitative information about age-related decline in systemic clearance and potential DDIs. The agreement between the two information sources was tested with κ statistics.

RESULTS

The literature reported age-related clearance changes for 13 antidepressants, whereas the PIs only had evidence about 4 antidepressants (κ < 0.4). Similarly, the literature identified 45 medications that could potentially interact with a specific antidepressant, whereas the PIs only provided evidence about 12 potential medication-antidepressant DDIs (κ < 0.4).

CONCLUSION

The evidence-based literature compared with PIs is the most complete pharmacotherapy information source about both age-related clearance changes and pharmacokinetic DDIs with antidepressants. Future rigorously designed observational studies are needed to examine the combined risk of antidepressants with age-related decline in clearance and potential DDIs on important health outcomes such as falls and fractures in older patients.

Therapeutic Options for Sleep-Maintenance and Sleep-Onset Insomnia

Insomnia, defined as difficulty falling asleep, staying asleep, and/or experiencing restorative sleep with associated impairment or significant distress, is a common condition resulting in significant clinical and economic consequences. Many options are available to treat insomnia, to assist with either falling asleep (sleep onset) or maintaining sleep. We searched MEDLINE for articles published between January 1996 and January 2006, evaluated abstracts from recent professional meetings, and contacted the manufacturer of the most recent addition to the pharmacologic armamentarium for insomnia treatment (ramelteon) to gather information. Nonpharmacologic options include stimulus control, sleep hygiene education, sleep restriction, paradoxical intention, relaxation therapy, biofeedback, and cognitive behavioral therapy. Prescription and over-the-counter drug therapies include benzodiazepine and nonbenzodiazepine sedative-hypnotic agents; ramelteon, a melatonin receptor agonist; trazodone; and sedating antihistamines. Herbal and alternative preparations include melatonin and valerian. Before recommending any treatment, clinicians should consider patient-specific criteria such as age, medical history, and other drug use, as well as the underlying cause of the sleep disturbance. All pharmacotherapy should be used with appropriate caution, at minimum effective doses, and for minimum duration of time.

Sleep in the Elderly: Burden, Diagnosis, and Treatment

Insomnia is commonly seen in elderly populations and is associated with numerous individual and socioeconomic consequences. Elderly patients are more likely to suffer from chronic insomnia characterized by difficulty maintaining sleep than difficulty initiating sleep. Management of insomnia in these patients requires very careful evaluation and exclusion of an underlying medical or psychiatric condition. Nonpharmacologic interventions in elderly patients, especially use of behavioral therapy, have demonstrated some success. Commonly prescribed medications have also been effective, though they have limitations. Newer agents currently under investigation for insomnia hold promise for good efficacy and safety in the elderly population. The following review presents clinical studies, survey results, and guidelines retrieved from peer-reviewed journals in the PubMed database using the search terms elderly, temazepam, trazodone, zolpidem, zaleplon, insomnia, and prevalence and the dates 1980 to 2003. In addition, newer research with emerging agents has been included for completeness.

Treatment of Anxiety and Depression in Transplant Patients

Depressive and anxiety disorders appear during the transplant process due to psychological stressors, medications and physiological disturbances. Treatment is necessary to prevent impact on patient compliance, morbidity and mortality. Psychotropic medications provide an effective option, although most are only available as oral formulations. Because of this, they are more susceptible to alterations in pharmacokinetic behaviour arising from organ dysfunction in the pretransplant period. Kinetics are also an issue when considering potential drug-drug interactions before and after transplantation. Prior to transplant, organ dysfunction can change the pharmacokinetic behaviour of some psychotropic agents, requiring adjustment of dosage and schedules. Thoracic or abdominal organ failure may reduce drug absorption through disturbances in intestinal motility, perfusion and function. Cirrhotic patients experience increased drug bioavailability due to portosystemic shunting, and thus dosage is adjusted downward. In contrast, dosage needs to be raised when peripheral oedema expands the drug distribution volume for hydrophilic and protein-bound agents. Drug clearance for most psychotropic medications is dependent upon hepatic metabolism, which is often disrupted by endstage organ disease. Selection of drugs or their dosage may need to be adjusted to lower the risk of drug accumulation. Further adjustments in dosage may be called for when renal failure accompanies thoracic or abdominal organ failure, resulting in further impairment of clearance. Studies regarding the treatment of anxiety and depressive disorders in the medically ill are limited in number, but recommendations are possible by review of clinical and pharmacokinetic data. Selective serotonin reuptake inhibitors are well tolerated and efficacious for depression, panic disorder and post-traumatic stress disorder. Adjustments in dosage are required when renal or hepatic impairment is present. Among them, citalopram and escitalopram appear to have the least risk of drug-drug interactions. Paroxetine has demonstrated evidence supporting its use with generalised anxiety disorder. Venlafaxine is an alternative option, beneficial in depression, post-traumatic stress and generalised anxiety disorders. Nefazodone may also be considered, but there is some risk of hepatotoxicity and interactions with immunosuppressant drugs. Mirtazapine still needs to be studied further in anxiety disorders, but can be helpful for depression accompanied by anorexia and insomnia. Bupropion is effective in the treatment of depression, but data are sparse about its use in anxiety disorders. Psychostimulants are a unique approach if rapid onset of antidepressant action is desired. Acute or short-term anxiolysis is obtained with benzodiazepines, and selection of particular agents entails consideration of distribution rate, half-life and metabolic route.

Unusually low clearance of two CYP3A substrates, alprazolam and trazodone, in a volunteer subject with wild-type CYP3A4 promoter region

A healthy 40-year-old Caucasian male volunteer displayed unusually low clearance and long elimination half-life of alprazolam and trazodone, two CYP3A substrate drugs, following single-dose oral administration in clinical pharmacokinetic studies. Genomic DNA isolated from the individual's peripheral blood was subjected to polymerase chain reaction amplification and subsequent sequence analysis of a 592 base-pair segment upstream from the CYP3A coding region. The analysis revealed no variation from wild-type in the nucleotide present at position -290, previously suggested to influence expression and/or activity of CYP3A. The functional significance of this promoter region mutation is unclear and requires further evaluation.

Antidepressants in the elderly: a review

The elderly constitute a growing proportion of our population for whom depression represents a significant problem. The choice of antidepressants available to the clinician is huge, and this article reviews the available literature on this important subject to facilitate evidence-based treatment decisions.

The efficacy, safety and tolerability of antidepressants in late life depression: a meta-analysis

BACKGROUND

To determine the efficacy, safety and tolerability of antidepressants in depressed elderly patients.

METHODS

Search for randomized controlled double-blind studies evaluating atypical antidepressants (ATYPs), reversible inhibitors of monoamine oxidase-A, selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants in moderate/severe depressed patients > or = 60 years for > or = four weeks. The random effects model (single-arm; comparative) was used to aggregate efficacy, safety and dropout.

RESULTS

No difference in single-arm aggregation of outcomes for four antidepressant classes. Comparative analyses showed no statistical difference between outcomes, except SSRIs had a higher response rate than ATYPs.

CONCLUSION

Elderly show no differences in antidepressant class outcomes.

LIMITATIONS

Heterogeneity and lack of power.

CLINICAL RELEVANCE

There is little advantage for antidepressant classes over another in the aged.

Critical flicker fusion threshold and anticholinergic effects of chronic antidepressant treatment in remitted depressives

The persistence of deficits in cognitive performance in major depressive patients taking maintenance antidepressant medication was assessed by examining groups of patients in clinical remission, stable on one of a range of tricyclics or selective serotonin re-uptake inhibitors (SSRIs) for at least 3 months, compared with controls. Measures of critical flicker fusion (CFF), choice reaction time (CRT), subjective sedation, and anticholinergic side-effect score were made. Tricyclic antidepressants (TCAs) produce a significant deficit in critical flicker fusion threshold compared both to controls and SSRIs. Similar effects were seen with choice reaction times which were significantly affected by age. Sedation scores were significantly higher with TCAs than SSRIs. Anticholinergic side effects were strongly related to CFF, less so to visual analogue sedating scales and not significantly to CRT. The effect measured by CFF is different from sedation, and may be related to the anticholinergic potency of the drug; it may be considered a drug-induced pseudodementia. This effect represents a risk factor for accidents during maintenance therapy and may impair work and leisure performance. The relative risk of weight gain with TCAs compared to SSRIs in women was 5.92 (95% CI 1.79-19.50).

Clinical and polysomnographic effects of trazodone CR in chronic insomnia associated with dysthymia

Six middle aged subjects complaining of chronic insomnia associated with dysthymia were investigated in a 2-month single blind study: a 7-day placebo treatment period, followed by a 6-week phase with increasing doses of trazodone controlled release (CR) formulation (50 mg through days 8-10; 75 mg through days 11-13; 150 mg through days 14-49) and then a final 7-day withdrawal period under placebo. Medication was always administered at bedtime. Five polysomnographic recordings were accomplished by each subject (sleep 1: under baseline placebo; sleep 2-3-4; under active treatment; sleep 5: after drug discontinuation). A "blind" EEG reader analysed the traditional polysomnographic variables (macrostructure of sleep) and the amount and percentage ratio (CAP rate) of cyclic alternating pattern (CAP), the microstructural parameter that measures the instability of arousal during sleep. Visual analogue scales (VAS) for the evaluation of subjective sleep quality and the Hamilton rating scale for depression (HAM-D) were regularly assessed across the study. Statistical analysis was based on an ANOVA test with repeated measures completed by means of Bonferroni adjusted probabilities. No significant differences emerged from the macrostructural parameters referred to sleep initiation and maintenance, while significant overall modifications emerged from stage 2 (P < 0.0005), slow wave sleep (P < 0.0001), total CAP time (P < 0.0001) and CAP rate (P < 0.0001). Compared to the placebo baseline night, a significant increase of slow wave sleep (+40 min) and significant reductions of stage 2 (-67 min), CAP time (-90 min) and CAP rate (-23%) were already found on day 4 of treatment (sleep 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacology of antidepressants--characteristics of the ideal drug

OBJECTIVE

To describe the clinical and basic pharmacologic properties of antidepressants and thus define the pharmacologic criteria for the ideal antidepressant.

DESIGN

A review of the pharmacologic characteristics of the newer second-generation antidepressants is presented in relationship to those of the older compounds.

MATERIAL AND METHODS

Clinical pharmacologic and in vitro data on the synaptic effects of antidepressants (inhibition of synaptosomal uptake and blockade of neurotransmitter receptors) were obtained for the older antidepressants and for the more recently marketed and approved drugs. The group of antidepressants includes six new antidepressants approved for marketing since 1988 and two additional drugs marketed outside the United States as antidepressants but approved for use in the United States for obsessive-compulsive disorder. Thus, 18 antidepressant drugs are discussed.

RESULTS

All antidepressants seem to be equally efficacious in treating depression, and no drug seems to work more rapidly than another. Nonetheless, antidepressant drugs differ substantially in pharmacokinetic variables (elimination half-lives); in their effects on the metabolism of other drugs (by inhibiting the cytochrome P450 system); in their potencies for blocking the reuptake of norepinephrine, serotonin, and dopamine; and in their affinities for blocking histamine H1, muscarinic acetylcholine, alpha 1-adrenergic, and dopamine D2 receptors. Most side effects of antidepressants can be explained by their effects on blocking uptake and on blocking neurotransmitter receptors.

CONCLUSION

The newer second-generation antidepressants have distinct pharmacologic advantages in comparison with the tricyclic antidepressants and the older second-generation compounds. These advantages are clearly seen from their synaptic effects, in which most newer second-generation antidepressants are practically devoid of blocking effects at neurotransmitter receptors. Although the newer second-generation antidepressants are much closer to being the ideal antidepressant than are the older compounds, none completely fulfills the criteria for being the ideal drug.

Pharmacokinetic optimisation of therapy with newer antidepressants

Since the early 1950s, when imipramine was first introduced, a whole series of antidepressants with differences in structures, neurochemical effects and pharmacokinetics have been developed. Structurally or functionally, they have been classified as tricyclic antidepressants (TCAs), tetracyclic antidepressants, monoamine oxidase inhibitors (MAOIs), or selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors (SSRIs). In addition, there is a series of antidepressants with unique structures. Many of the newer TCAs appear to have shorter half-lives than the standard TCAs (e.g. imipramine), allowing for the possibility of a more rapid response, but requiring the drugs to be given in multiple daily doses, which may reduce patient compliance. The short time to peak plasma concentration (tmax) can also lead to rapid onset of adverse effects. The tetracyclic antidepressants have longer elimination half-lives (t1/2) than the TCAs, but there is only very minimal evidence for a relationship between drug concentrations in the blood and clinical response. The triazolopyridines, like the newer TCAs, show pharmacokinetic evidence for rapid onset of adverse effects and the need for multiple daily doses due to short tmax and t1/2. The newer MAOIs are a significant addition to therapy, as the rapid binding action of these medications increases their safety margin with regard to tyramine interactions. Further information in this area is required. In addition, moclobemide has pharmacokinetic features that are clinically beneficial (e.g. aging and renal dysfunction have little effect on the elimination of the drug), but also features that are not beneficial (e.g. nonlinear pharmacokinetics). Among the SSRIs, there are a range of t1/2 values for the parent drugs, from relatively short t1/2 values of less than 24 hours (paroxetine, fluvoxamine) to among the longest found (e.g. 2 days for fluoxetine). Only 2 of the agents (sertraline and citalopram) have linear pharmacokinetics, and 1 drug has nonlinear pharmacokinetics within the usual therapeutic range (fluvoxamine). Once a therapeutic blood concentration is established, linearity is helpful in avoiding the small dose changes and repeated rechecking of concentrations of medications that would be required for those agents with nonlinear pharmacokinetics. Sertraline stands out as having the best effects on behaviour among all antidepressants. However, fluoxetine and fluvoxamine are least likely to penetrate into breast milk. All 3 of the structurally unique newer antidepressants [amfebutamone (bupropion), viloxazine venlafaxine] have relatively short tmax values (1 to 2 hours), which may relate to the early onset of adverse effects. Amfebutamone has the benefits of linear pharmacokinetics with potential for defined therapeutic blood concentrations, lack of effect of liver enzymes on metabolism of the drug, and lack of significant effects of either aging or hepatic dysfunction on elimination of the drug. Thus, the antidepressants best suited for pharmacokinetic optimisation of therapy are the following: desipramine, sertraline, fluvoxamine, citalopram and amfebutamone.

Trazodone. A review of its pharmacology, therapeutic use in depression and therapeutic potential in other disorders

Trazodone is a triazolopyridine derivative, chemically and pharmacologically unrelated to other currently available antidepressants. It possesses antidepressant, and also some anxiolytic and hypnotic activity. Results from a small number of short term (4 to 6 weeks) comparative studies in a total of 320 evaluable elderly patients with major depression, suggest that trazodone at therapeutic doses is superior to placebo and as effective as amitriptyline, imipramine, fluoxetine and mianserin in relieving depressive symptoms. Trazodone has also been successfully used in a small number of patients with depression and pre-existing cardiovascular disease. More recently, trazodone has been used as a hypnotic for psychotropic-induced or other insomnias with some success. However, further clinical experience is needed to confirm these preliminary results. In the elderly, maximum tolerated doses of trazodone are 300 to 400 mg/day, although higher doses of up to 600 mg/day are tolerated by younger patients. Drowsiness is commonly reported, but the incidences of both anticholinergic and cardiovascular effects were notably lower in elderly patients treated with trazodone compared with older tricyclic antidepressants. However, undesirable effects such as orthostatic hypotension, arrhythmias and priapism need to be closely monitored. In comparison with other currently available agents, particularly the tricyclic antidepressants, trazodone is relatively safe in overdose. In terms of therapeutic efficacy, trazodone appears to confer little advantage over other available antidepressants. While limited data suggest that trazodone may be better tolerated than older tricyclic antidepressants, especially in the elderly, there is a paucity of data at present comparing trazodone with the secondary amine tricyclic agents, serotonin reuptake inhibitors or moclobemide. Bearing this in mind, trazodone may be of use in elderly patients in whom anxiety and insomnia are problematic, and in those patients who are unresponsive to or cannot tolerate therapy with other agents. Studies are also required to define the place of trazodone in long term prophylactic therapy for recurrent depression. Future trials comparing both its efficacy and tolerability with those of newer agents will ascertain whether trazodone becomes a first line agent within these subsets of elderly patients.

Pharmacokinetic and pharmacodynamic characteristics of a controlled-release formulation of trazodone versus the conventional formulation in healthy volunteers

The pharmacokinetic and pharmacodynamic characteristics of a controlled-release (CR) formulation of trazodone were evaluated in healthy subjects who received acutely 150 mg and 75 mg of the CR trazodone and equal amounts of the conventional formulation on separate occasions. Plasma trazodone concentrations were measured by HPLC. The pharmacokinetic profile of CR trazodone was characterized by a slower increase in drug plasma levels and a lower and retarded peak plasma concentration without any modification in the total amount of trazodone absorbed over 24 hrs. The side effects were less severe and less frequent than with the conventional formulation.

Pharmacokinetic aspects of antidepressant treatment in the elderly

1. Physiological and metabolic changes with ageing may affect the pharmacokinetics of antidepressant drugs. 2. Pharmacokinetic parameters following single doses of antidepressants in the elderly tend to be altered compared with younger subjects. 3. Elimination half-life tends to be prolonged for most antidepressant drugs in the elderly due to decreased clearance and increased volume of distribution. 4. Steady-state plasma concentrations tend to be increased in elderly patients. 5. Inter-individual differences usually account for the majority of the variance in kinetic parameters rather than an effect of ageing per se. 6. The increased propensity for side effects in the elderly is probably due to pharmacodynamic rather than pharmacokinetic alterations with age.

Pharmacokinetics of trazodone during multiple dosing to psychiatric patients

Steady-state pharmacokinetics of trazodone were investigated over a period of 4 weeks in seven psychiatric patients after repeated oral administrations of 50, 100, and 150 mg twice daily for one, one, and two consecutive weeks, respectively. Unchanged trazodone was determined by high performance liquid chromatography after a basic extraction. A steady-state level of serum trazodone was achieved for the 50 mg dose within 36 hr, while a new steady state level after increasing the dose to 100 mg and then 150 mg twice daily apparently was achieved at 12 hr. Trazodone showed linear pharmacokinetics within the dosage range investigated. The following main parameters were calculated at steady state for psychiatric patients (mean +/- S.D.): t 1/2 = 7.0 +/- 1.2, V beta/F = 0.50 +/- 0.13 l/kg and Clt/F = 3.2 +/- 0.5 l/hr. These pharmacokinetic parameters did not differ significantly from those earlier reported in healthy subjects after a single dose administration of 100 mg when based on an oral availability of trazodone of 65%.

Clinical pharmacokinetics of antidepressants in the elderly. Therapeutic implications

The prevalence of depression in the elderly suggests that a substantial number of older patients will be treated with an antidepressant medication such as one of the tricyclics, trazodone, fluoxetine or lithium. The physiological changes that accompany aging raise the possibilities of altered pharmacokinetics, patterns of efficacy and adverse effect profiles. The literature addressing the subject of antidepressant use in the elderly has not provided a clear, consistent picture of how these drugs behave in this population in comparison with younger patients. Particularly in the case of the tricyclic antidepressants (TCAs), a large degree of interindividual variation in drug clearance (CL) confounds attempts to find differences attributable to age per se. Study design, however, is also a problem in that very few investigators include a young control group, choosing instead to compare their data with previously reported outcomes. Designations of statistical significance and positive correlation also differ among investigators, and the clinical significance of any finding is not always addressed. The available data suggest that imipramine CL is reduced in the elderly and that amitriptyline CL may be reduced. Desipramine CL does not appear to be affected by age, although decreased renal function in the elderly may lead to accumulation of the hydroxylated metabolite, the clinical importance of which is not known. Nortriptyline is the most thoroughly studied TCA in the elderly. CL seems decisively lower only in elderly patients with concurrent medical illness. The hydroxylated metabolite probably accumulates with diminishing renal function. Not enough data are available on doxepin to make a conclusion. Trazodone CL is diminished somewhat in elderly men. Lithium CL appears to diminish with the declining renal function associated with aging. Fluoxetine data are sparse. Available data do not show any decrease in CL of the parent drug; more information is needed on the metabolite norfluoxetine. Although knowledge of CL changes with aging can help the clinician more accurately achieve the desired steady-state concentration of a drug during long term therapy, much work is still needed to evaluate the relationships among drug concentrations at steady-state, efficacy and adverse effects in the elderly.

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.

Single dose pharmacokinetics of trazodone in healthy subjects

Eight healthy subjects were administered trazodone-HCl orally (100 mg) with and without food and by infusion in a three way cross-over study. Unchanged trazodone was determined in serum and urine by high performance liquid chromatography after an alkaline extraction. Absorption of trazodone was irregular in fasting subjects and improved after food intake. Food intake significantly decreased the maximum serum concentrations of trazodone from 1.88 +/- 0.42 to 1.47 +/- 0.16 micrograms/ml, and increased the time for reaching maximum concentration from 1.3 +/- 0.8 hr to 2.0 +/- 1.5 hr. No differences were observed in the total amount of trazodone absorbed with or without food with bioavailability values of 65 +/- 6 and 63 +/- 4 per cent, respectively. The apparent volume of distribution and total body clearance for trazodone were estimated to 0.84 +/- 0.16 l/kg and 5.3 +/- 0.9 l/hr, respectively. The terminal elimination half-life of 7.3 +/- 0.8 hr showed no significant differences between the different ways of administration. Urinary excretion of unchanged trazodone during 26 hr was less than 0.13 per cent of the administered dose, suggesting a high degree of trazodone metabolism. Earlier statements of enterohepatic circulation of trazodone and pharmacokinetic differences between males and females were not confirmed by the present study. Due to the irregular absorption in fasting subjects, trazodone should preferably be administered after food.

Hepatic drug metabolism and aging

Although there is considerable variation in the effect of age on drug biotransformation, the metabolism of many drugs is impaired in the elderly. Age-related physiological changes, such as a reduction in liver mass, hepatic metabolising enzyme activity, liver blood flow and alterations in plasma drug binding may account for the decreased elimination of some metabolised drugs in the elderly. It is difficult, however, to separate an effect of aging from a background of marked variation in the rate of metabolism due to factors such as individual metabolic phenotype, environmental influences, concomitant disease states and drug intake. The prevailing data suggest that initial doses of metabolised drugs should be reduced in older patients and then modified according to the clinical response. In most studies the elderly appear as responsive as young individuals to the effects of compounds which induce or inhibit the activity of cytochrome P450 isozymes. Concurrent use of other agents, which induce or inhibit drug metabolism, mandates dose adjustment as in younger patients. Many questions remain unanswered. For instance, limitations of in vitro studies prevent any firm conclusion about changes in hepatic drug metabolising enzyme activity in the elderly. With aging, some pathways of drug metabolism may be selectively affected, but this has not been adequately scrutinised. The possibility that metabolism of stereoisomers may be altered in the elderly has not been adequately tested. The effect of aging on the distribution of polymorphic drug metabolism phenotypes is still not established, despite potential implications for disease susceptibility and survival advantage.

Effects of a controlled-release formulation of trazodone on psychomotor and autonomic functions in healthy volunteers: comparison with trazodone (conventional formulation), amitriptyline and placebo

Eight healthy male volunteers participated in four experimental sessions. In each session the subjects ingested a single dose of one of the following drugs: trazodone (controlled-release formulation), trazodone (conventional formulation), amitriptyline and placebo. Both trazodone and amitriptyline reduced subjectively rated alertness and increased digit cancellation time, and amitriptyline also reduced critical flicker fusion frequency. Both antidepressants reduced salivation, trazodone also caused miosis. There were no consistent differences between the effects of the two formulations of trazodone. The results of the psychological tests are indicative of the sedative properties of the antidepressants. It is likely that the reduction in salivation and pupil diameter by trazodone reflect alpha-adrenoceptor blockade, whereas the reduction in salivation by amitriptyline may be due to both cholinoceptor and alpha-adrenoceptor blockade.

Trazodone in late life depressive states: a double-blind multicenter study versus amitriptyline and mianserin

Seventy five elderly depressed in-patients, ages ranging from 60 to 83 years, diagnosed as Major Depression according to DSM III were treated, under double-blind conditions, with 75 mg Amitriptyline (AMI) (26 patients), 60 mg Mianserin (MIA) (24 patients) or 150 mg Trazodone (TRZ) (25 patients) p.o. for 5 weeks. There were no differences in the clinical outcome between the three groups of patients at the end of the trial, with a significant amelioration (P less than 0.01) at the Hamilton Rating Scale for Depression and Geriatric Depression Scale. TRZ showed a significantly lower incidence of side effects compared to MIA and AMI. Atypical antidepressants, including TRZ, seem more suitable for treating elderly depression than the first generation antidepressants on the basis of risk/benefit ratio considerations.

Excretion of trazodone in breast milk

The excretion of breast milk was studied in six lactating women following the oral administration of a single trazodone tablet (50 mg). The milk/plasma ratio of trazodone based on area under the plasma and milk curves was small: 0.142 +/- 0.045 (mean +/- s.d.). Assuming that the babies would drink 500 ml 12 h-1, they would be exposed to less than 0.005 mg kg-1 as compared to 0.77 mg kg-1 for the mothers. It is concluded that exposure of babies to trazodone via breast milk is very small.

An evaluation of possible interactions between ethanol and trazodone or amitriptyline

The pharmacodynamic effects of single doses of trazodone (100 mg), amitriptyline (50 mg) or placebo either alone or with ethanol (0.5 ml/kg) were investigated in six healthy volunteers in a double-blind crossover study. Plasma concentrations of the drugs and ethanol were also measured. Pharmacodynamic tests were critical flicker fusion frequency threshold (CFF), choice reaction time (CRT), manual dexterity, a digit span test and visual analogue scales. Blood ethanol concentrations were not influenced by the co-administration of either antidepressant. tmax for trazodone was prolonged by ethanol but the other pharmacokinetic parameters for trazodone and amitriptyline were not influenced by ethanol. Trazodone and amitriptyline caused the expected profound depressant effects on CFF, CRT, manual dexterity and on the rating scales for drowsiness, 'clear-headedness', aggression and disinhibition. Ethanol alone impaired manual dexterity, increased drowsiness, reduced 'clear headedness' and also tended to reduce feelings of aggression. In combination with either trazodone or amitriptyline, ethanol caused little additional effect except in the case of manual dexterity which was further impaired. This result may reflect the profound effects of the antidepressants alone and does not suggest that it is safe for patients receiving antidepressant medication to take ethanolic drinks.