Effects of various tricyclic antidepressants on amine uptake

Tools for optimising pharmacotherapy in psychiatry (therapeutic drug monitoring, molecular brain imaging and pharmacogenetic tests): focus on antidepressants

Objectives: More than 40 drugs are available to treat affective disorders. Individual selection of the optimal drug and dose is required to attain the highest possible efficacy and acceptable tolerability for every patient.Methods: This review, which includes more than 500 articles selected by 30 experts, combines relevant knowledge on studies investigating the pharmacokinetics, pharmacodynamics and pharmacogenetics of 33 antidepressant drugs and of 4 drugs approved for augmentation in cases of insufficient response to antidepressant monotherapy. Such studies typically measure drug concentrations in blood (i.e. therapeutic drug monitoring) and genotype relevant genetic polymorphisms of enzymes, transporters or receptors involved in drug metabolism or mechanism of action. Imaging studies, primarily positron emission tomography that relates drug concentrations in blood and radioligand binding, are considered to quantify target structure occupancy by the antidepressant drugs in vivo. Results: Evidence is given that in vivo imaging, therapeutic drug monitoring and genotyping and/or phenotyping of drug metabolising enzymes should be an integral part in the development of any new antidepressant drug.Conclusions: To guide antidepressant drug therapy in everyday practice, there are multiple indications such as uncertain adherence, polypharmacy, nonresponse and/or adverse reactions under therapeutically recommended doses, where therapeutic drug monitoring and cytochrome P450 genotyping and/or phenotyping should be applied as valid tools of precision medicine.

Antidepressants and risk of upper gastrointestinal bleeding

Selective serotonin reuptake inhibitors (SSRIs) are nowadays the most widely used antidepressants in the world, mainly because they have a better adverse reaction profile and a higher safety margin in overdoses, when compared to other antidepressants. These drugs recently have been the target of important debates concerning safety issues, among them the possibility that they may increase the risk of bleeding. Over the 1990s, an increasing number of individual cases of bleeding disorders were reported in the literature and to the pharmacovigilance programmes which prompted several epidemiological and pharmacological studies. In this review we have examined all available data. The whole evidence supports the hypothesis that antidepressants with a relevant blockade action on serotonin reuptake mechanism increase the risk of bleeding. Such disorders may have different degrees of severity and may be located anywhere in the body. The epidemiological evidence is, however, more robust for upper gastrointestinal bleeding. It has been estimated that upper gastrointestinal bleeding may occur at a frequency ranging from 1 in 100 to 1 in 1,000 patient-years of exposure to high-affinity drugs (the SSRIs), with the very old patients being in the highest part of the range. The increased risk may be of particular relevance when the SSRIs are associated with NSAIDs as well as low-dose aspirin.

Association between selective serotonin reuptake inhibitors and upper gastrointestinal bleeding: population based case-control study

OBJECTIVE

To examine the association between selective serotonin reuptake inhibitors and risk of upper gastrointestinal bleeding.

DESIGN

Population based case-control study.

SETTING

General practices included in the UK general practice research database.

SUBJECTS

1651 incident cases of upper gastrointestinal bleeding and 248 cases of ulcer perforation among patients aged 40 to 79 years between April 1993 and September 1997, and 10 000 controls matched for age, sex, and year that the case was identified.

INTERVENTIONS

Review of computer profiles for all potential cases, and an internal validation study to confirm the accuracy of the diagnosis on the basis of the computerised information.

MAIN OUTCOME MEASURES

Current use of selective serotonin reuptake inhibitors or other antidepressants within 30 days before the index date.

RESULTS

Current exposure to selective serotonin reuptake inhibitors was identified in 3.1% (52 of 1651) of patients with upper gastrointestinal bleeding but only 1.0% (95 of 10 000) of controls, giving an adjusted rate ratio of 3.0 (95% confidence interval 2.1 to 4.4). This effect measure was not modified by sex, age, dose, or treatment duration. A crude incidence of 1 case per 8000 prescriptions was estimated. A small association was found with non-selective serotonin reuptake inhibitors (relative risk 1.4, 1.1 to 1.9) but not with antidepressants lacking this inhibitory effect. None of the groups of antidepressants was associated with ulcer perforation. The concurrent use of selective serotonin reuptake inhibitors with non-steroidal anti-inflammatory drugs increased the risk of upper gastrointestinal bleeding beyond the sum of their independent effects (15.6, 6.6 to 36.6). A smaller interaction was also found between selective serotonin reuptake inhibitors and low dose aspirin (7.2, 3.1 to 17.1).

CONCLUSIONS

Selective serotonin reuptake inhibitors increase the risk of upper gastrointestinal bleeding. The absolute effect is, however, moderate and about equivalent to low dose ibuprofen. The concurrent use of non-steroidal anti-inflammatory drugs or aspirin with selective serotonin reuptake inhibitors greatly increases the risk of upper gastrointestinal bleeding.

Acceleration of rat brain beta-adrenoceptor subsensitivity following the coadministration of histamine receptor antagonists with imipramine

Systemic administration of isoprenaline to rats produced a dose-dependent increase in water drinking which was effectively blocked by propranolol. This dipsogenic effect was significantly inhibited by the subacute (4 days) administration of imipramine (18.1 mg/kg/day) together with either the H1-histamine receptor antagonist, chlorpheniramine (0.1 or 1.32 mg/kg/day), or the H2-histamine antagonist, cimetidine (1.91 mg/kg/day) or ranitidine (0.60 or 1.51 mg/kg/day). The oral subacute administration of imipramine alone had no significant effect on this behavior. However, chronic ingestion of imipramine alone (21 days) caused a significant reduction in the isoprenaline-induced behavior. It is concluded that the desensitization of central beta-adrenoceptors, as evidenced by inhibition of isoprenaline-induced drinking, can be accelerated following the oral subacute co-administration of imipramine with either H1- or H2-histamine receptor antagonists. It is also seems the central histamine receptors may partially contribute towards the mechanism of antidepressant effect of imipramine.

Dothiepin. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in depressive illness

Dothiepin is a tricyclic antidepressant that is structurally related to amitriptyline. It appears that the antidepressant activity of dothiepin is mediated through facilitation of noradrenergic neurotransmission by uptake inhibition and possibly also by enhancement of serotoninergic neurotransmission. The overall therapeutic efficacy of dothiepin is very similar to that of amitriptyline. In addition, dothiepin appears to be comparable to imipramine, doxepin, maprotiline, mianserin, fluoxetine, fluvoxamine and trazodone. Dry mouth is the most commonly reported side effect of therapeutic doses but the incidence of this and other anticholinergic side effects is less among patients treated with dothiepin than with amitriptyline. However, the sedative/anxiolytic activity of dothiepin is similar to that of amitriptyline. Dothiepin has not been associated with cardiotoxicity at therapeutic doses. Thus, many years of extensive clinical use have shown that dothiepin is now an established and effective antidepressant in both inpatients and outpatients with depressive symptoms of varying severity and coexisting anxiety. Its therapeutic equivalence to other tricyclics ensures its place as a treatment alternative in these disorders.

Determination of dosulepin and its metabolite: application of high-performance liquid chromatography with electrochemical detection

Dosulepin, 11-(3-dimethylaminopropylidene)-6,11-dihydrodibenzo [b,e]thiepin hydrochloride, is a thio analogue of amitriptyline and is used for the treatment of anxiety and affective disorders. The present study developed a simple and sensitive procedure for the determination of this compound and its metabolite, northiaden, by a combination of high-performance liquid chromatography with electrochemical detection. Hydrodynamic voltammograms demonstrated an optimal applied potential at 1300 mV for both dosulepin and northiaden. A mobile phase consisting of 0.1 M acetate buffer-acetonitrile-perchloric acid-trichloroacetic acid (50:50:2:1.5) provided the best separation of the drugs. The extraction procedure, which used a heptane-isoamyl alcohol (99:1) mixture, was successfully applied with a recovery of over 90%. A preliminary pharmacokinetic study was performed by the proposed method.