Clinical relevance of serum nortriptyline and 10-hydroxy-nortriptyline measurements in the depressed elderly: a multicenter pharmacokinetic and pharmacodynamic study

A Study on CYP2C19 and CYP2D6 Polymorphic Effects on Pharmacokinetics and Pharmacodynamics of Amitriptyline in Healthy Koreans

We performed a double-blinded, genotype-based stratification study to explore the pharmacokinetics and pharmacodynamics of amitriptyline according to CYP2C19 and CYP2D6 genotype in Korean subjects. Twenty-four healthy adults were grouped by genotype of CYP2C19 and CYP2D6. After a single dose of 25 mg of amitriptyline, blood samples were collected and anticholinergic effects were measured. The extent of N-demethylation of amitriptyline significantly decreased in subjects carrying two nonfunctional alleles of CYP2C19. The extent of hydroxylation of amitriptyline or nortriptyline was significantly reduced in subjects carrying two CYP2D6 decreased functional alleles compared with those with no or one decreased functional allele. The overall metabolic pathway of amitriptyline was more likely to be dominated by CYP2C19 than CYP2D6. The gene variations of CYP2C19 and CYP2D6 did not change the pharmacodynamic effect. The findings of this study will provide useful information on individualized drug treatment with amitriptyline considering both CYP2D6 and CYP2C19 gene variations.

A Model Based Cost-Effectiveness Analysis of Routine Genotyping for CYP2D6 among Older, Depressed Inpatients Starting Nortriptyline Pharmacotherapy

OBJECTIVE

Genotyping for CYP2D6 has the potential to predict differences in metabolism of nortriptyline. This information could optimize pharmacotherapy. We determined the costs and effects of routine genotyping for old aged Dutch depressed inpatients.

METHODS

With a decision-tree, we modelled the first 12 weeks of nortriptyline therapy. Direct costs of genotyping, hospitalization, therapeutic drug monitoring and drugs were included. Based on genotype, patients could be correctly, sub-, or supratherapeutically dosed. Improvement from sub- or supratherapeutically dosed patients to correctly dosed patients was simulated, assuming that genotyping would prevent under- or overdosing of patients. In the base case, this improvement was assumed to be 35%. A probabilistic sensitivity analysis (PSA) was performed to determine uncertainty around the incremental cost-effectiveness ratio (ICER).

RESULTS

In the base case analysis, costs for genotyping were assumed €200 per test with a corresponding ICER at €1 333 000 per QALY. To reach a €50 000 per QALY cut-off, genotyping costs should be decreased towards €40 per test. At genotyping test costs < €35 per test, genotyping was dominant. At test costs of €17 per test there was a 95% probability that genotyping was cost-effective at €50 000 per QALY.

CONCLUSIONS

CYP2D6 genotyping was not cost-effective at current genotyping costs at a €50 000 per QALY threshold, however at test costs below €40, genotyping could be costs-effective.

Antidepressant-induced akathisia-related homicides associated with diminishing mutations in metabolizing genes of the CYP450 family

PURPOSE

To examine the relation between variant alleles in 3 CYP450 genes (CYP2D6, CYP2C9 and CYP2C19), interacting drugs and akathisia in subjects referred to a forensic psychiatry practice in Sydney, Australia.

PATIENTS AND METHODS

This paper concerns 10/129 subjects who had been referred to the first author's practice for expert opinion or treatment. More than 120 subjects were diagnosed with akathisia/serotonin toxicity after taking psychiatric medication that had been prescribed for psychosocial distress. They were tested for variant alleles in CYP450 genes, which play a major role in Phase I metabolism of all antidepressant and many other medications. Eight had committed homicide and many more became extremely violent while on antidepressants. Ten representative case histories involving serious violence are presented in detail.

RESULTS

Variant CYP450 allele frequencies were higher in akathisia subjects compared with random primary care patients tested at the same facility. Ten subjects described in detail had variant alleles for one or more of their tested CYP450 genes. All but two were also on interacting drugs, herbals or illicit substances, impairing metabolism further. All those described were able to stop taking antidepressants and return to their previously normal personalities.

CONCLUSION

THE PERSONAL, MEDICAL, AND LEGAL PROBLEMS ARISING FROM OVERUSE OF ANTIDEPRESSANT MEDICATIONS AND RESULTING TOXICITY RAISE THE QUESTION: how can such toxicity events be understood and prevented? The authors suggest that the key lies in understanding the interplay between the subject's CYP450 genotype, substrate drugs and doses, co-prescribed inhibitors and inducers and the age of the subject. The results presented here concerning a sample of persons given antidepressants for psychosocial distress demonstrate the extent to which the psychopharmacology industry has expanded its influence beyond its ability to cure. The roles of both regulatory agencies and drug safety "pharmacovigilantes" in ensuring quality and transparency of industry information is highlighted.

Antidepressants for depressed elderly

BACKGROUND

Depression is a relatively common experience in older adults. The syndrome is associated with considerable distress, morbidity and service commitment. Approximately two thirds of patients presenting with severe forms will respond to antidepressant treatment and the last twenty years has witnessed a great increase in the number of these drugs. Older, frail people are particularly vulnerable to side effects.

OBJECTIVES

The aims of this review were to examine the efficacy of antidepressant classes, to compare the withdrawal rates associated with each class and describe the side effect profile of antidepressant drugs for treating depression in patients described as elderly, geriatric, senile or older adults, aged 55 or over.

SEARCH STRATEGY

The Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Register (CCDANCTR-Studies) was searched (2003-08-13). Reference lists of relevant papers and previous systematic reviews were hand searched for published reports and citations of unpublished studies.

SELECTION CRITERIA

Only randomised controlled trials were included. Trials had to compare at least two active antidepressant drugs in the treatment of depression.

DATA COLLECTION AND ANALYSIS

Reviewers extracted data independently. In examining efficacy, the reviewers assumed that people who died or dropped out had no improvement. Withdrawal rates irrespective of cause and specifically due to side effects were compared between drug classes. Relative risk (RR) for dichotomous data and weighted mean difference for continuous data were calculated with 95% confidence intervals (CI). Qualitative side effect data were reported in terms of ratios of side effects and percentage of patients experiencing specific side effects.

MAIN RESULTS

A total of 29 trials provided data for inclusion in the review. We were unable to find any differences in efficacy when comparing classes of antidepressants. However, as the trials contained relatively small numbers of patients, these findings may be explained by a type two error. Tricyclic antidepressants (TCAs) compared less favourably with selective serotonin reuptake inhibitors (SSRIs) in terms of numbers of patients withdrawn irrespective of reason (RR: 1.24, CI 1.04, 1.47) and number withdrawn due to side effects (RR: 1.30, CI 1.02, 1.64). Subgroup analyses demonstrated that TCA related antidepressants had similar withdrawal rates to SSRIs irrespective of reason of withdrawal (RR: 1.49, CI 0.74, 2.98) or withdrawal due to side effects (RR: 1.07, CI 0.43, 2.70). The qualitative analysis of side effects showed a small increased profile of gastro-intestinal and neuropsychiatric side effects associated with classical TCAs.

AUTHORS' CONCLUSIONS

Our findings suggest that SSRIs and TCAs are of the same efficacy. However, we have found some evidence suggesting that TCA related antidepressants and classical TCAs may have different side effect profiles and are associated with differing withdrawal rates when compared with SSRIs. The review suggests that classical TCAs are associated with a higher withdrawal rate due to side effect experience, although these results must be interpreted with caution due to the relatively small size of the review and the heterogeneity of the drugs and patient populations.

Association study of -1727 A/T, -50 C/T and (CAA)n repeat GSK-3beta gene polymorphisms with schizophrenia

Glycogen synthase kinase-3 (GSK-3) is a downstream component of the Wnt pathway and recent studies have reported abnormal levels of GSK-3beta in schizophrenia. In a sample of 147 schizophrenic patients and 212 healthy individuals, we analyzed two common SNPs at position -1727 A/T and -50 C/T and a (CAA)(n) repeat polymorphism localized in intron 1 of the gene. The results showed that the allele, genotype and haplotype distributions for the three polymorphisms investigated do not differ between schizophrenic patients in general and control subjects. However, in the subtype of paranoid schizophrenic patients, we found that the (CAA)(3)/(CAA)(5) heterozygotes were more often represented. Although taken from a small sample, our results support the reports that GSK-3beta appears to be involved in a subtype of schizophrenic patients, but not in schizophrenia in general. In conclusion, we would speculate that this gene may be linked to some features of psychotic disorders rather than to schizophrenia itself.

Neurodevelopmental schizophrenia: obstetric complications, birth weight, premorbid social withdrawal and learning disabilities

Neurodevelopmental schizophrenia seems to be caused by impaired cerebral development and is supposed to be associated with obstetric complications (OCs), poor premorbid adjustment, schizotypal or schizoid personality traits and negative symptoms. In the present study, 36 schizophrenic and schizoaffective patients and their same-sex, healthy siblings were recruited. They were diagnosed according to DSM-III-R, using structured psychiatric interviews and a consensus of 2 psychiatrists. Information on OCs, birth weight, premorbid social and learning functioning was obtained from their mothers. The main results show significant differences in OCs, birth weight, premorbid social and learning functioning between patients and their same-sex, healthy siblings. Using multivariate analyses, both premorbid variables were again identified to discriminate well between affected and unaffected siblings. Our findings seem to confirm the concept of schizophrenia as a neurodevelopmental process.

Antidepressant versus placebo for depressed elderly

BACKGROUND

Depression warranting intervention is found in ten percent of people over the age of 60. Older depressed people are more likely to die than non-depressed. Relatively few receive therapeutic interventions, and those that do, tend to receive low dose antidepressant therapy. Depression in older people is thought to differ in terms of aetiology, presentation, treatment and outcome than in younger people. Concomitant physical illness and increasing social, physical and neurophysiological diversity are associated with the ageing process. Consequently drug treatment of older patients is often carried out in institutions and on patients suffering from multiple physical problems.

OBJECTIVES

To determine the efficacy of antidepressant medication compared with placebo in the treatment of depression in older patients.

SEARCH STRATEGY

The search strategy incorporated: electronic literature searches of databases held by the Cochrane Collaboration Depression, Anxiety and Neurosis Review Group (CCDAN) (see Collaborative Review Group Search Strategy). Reference lists of related reviews and references of located studies. Contact was made with authors working in the field.

SELECTION CRITERIA

All randomised, placebo controlled trials using antidepressants in the treatment of the presenting episode of depression in patients described as elderly, geriatric senile or older adult.

DATA COLLECTION AND ANALYSIS

Two types of data were extracted (if available) from each study. The first type of data was dichotomous data, this consisted of recovered/not recovered. The second, continuous data,included: Hamilton Depression Rating Scale (HAM-D), Montgomery-Asberg Rating Scale (MADRS) and other depression rating scale scores. An analysis using Peto Odds ratios for the dichotomous data and weighted mean difference for continuous data was performed using RevMan 3.1. The presence of heterogeneity of treatment effect was assessed.

MAIN RESULTS

Seventeen trials contributed data to the analyses comparing the efficacy of antidepressant treatment and placebo. Analyses of efficacy was based on 245 patients treated with TCAs (223 with placebo), 365 patients treated with SSRIs (372 with placebo) and 58 patients treated with MAOIs (63 with placebo). The standardised effect size for the three groups respectively were: TCAs; OR: 0.32 (0.21,0.47), SSRIs; OR; 0.51 (0.36,0.72), MAOIs: 0.17 (0.07,0.39).

REVIEWER'S CONCLUSIONS

TCAs, SSRIs and MAOIs are effective in the treatment of older community patients and inpatients likely to have severe physical illness. At least six weeks of antidepressant treatment is recommended to achieve optimal therapeutic effect. There is little evidence concerning the efficacy of low dose TCA treatment. Further trials are required before low dose TCA treatment is routinely recommended.

Metabolism of tricyclic antidepressants

1. Despite the considerable advances in the treatments available for mood disorders over the past generation, tricyclic antidepressants (TCAs) remain an important option for the pharmacotherapy of depression. 2. The pharmacokinetics of TCAs are characterized by substantial presystemic first-pass metabolism, a large volume of distribution, extensive protein binding, and an elimination half-life averaging about 1 day (up to 3 days for protriptyline). 3. Clearance of tricyclics is dependent primarily on hepatic cytochrome P450 (CYP) oxidative enzymes. Although the activities of some P450 isoenzymes are largely under genetic control, they may be influenced by external factors, such as the concomitant use of other medications or substances. Patient variables, such as ethnicity and age, also affect TCA metabolism. The impact of gender and related reproductive issues is coming under increased scrutiny. 4. Metabolism of TCAs, especially their hydroxylation, results in the formation of active metabolites, which contribute to both the therapeutic and the adverse effects of these compounds. 5. Renal clearance of the polar metabolites of TCAs is reduced by normal aging, accounting for much of the increased risk of toxicity in older patients. 6. Knowledge of factors affecting the metabolism of TCAs can further the development and understanding of newer antidepressant medications.

Optimal sampling times for Bayesian estimation of the pharmacokinetic parameters of nortriptyline during therapeutic drug monitoring

Sampling times for Bayesian estimation of the pharmacokinetic parameters of an antidepressant drug, nortriptyline, during its therapeutic drug monitoring were optimized. Our attention was focused on designs including a limited number of measurements: one, two, and three sample designs in which sampling times had to be chosen between 0 and 24 hr after the last intake of a test-dose study. The optimization was conducted in four groups of patients defined by their gender and the administration or not of concomitant drugs inhibiting the metabolism of nortriptyline. The Bayesian design criterion was defined as the expected information provided by an experiment. A stochastic approximation algorithm, the Kiefer-Wolfowitz algorithm, was used for the criterion maximization under experimental constraints. Results showed that optimal Bayesian sampling times differ between patients in monotherapy and polytherapy. For one-sample designs the measurements have to be performed either at the lower (0 hr) or at the upper (24 hr) bound of the admissible interval. Replications were often found for 2- and 3-point designs. Other sampling designs can lead to criterion close to the optimum and can therefore be performed without great loss of information. In contrast, we found that several designs lead to low values of the information criterion, which justifies the approach.