Amoxapine shows atypical antipsychotic effects in patients with schizophrenia: results from a prospective open-label study

Molecular dynamics and free energy calculations of clozapine bound to D2 and H1 receptors reveal a cardiometabolic mitigated derivative

Most atypical antipsychotics derive from a high dropout of drug treatments due to adverse cardiometabolic side effects. These side effects are caused, in part, by the H1 receptor blockade. The current work sought a clozapine derivative with a reduced affinity for the H1 receptor while maintaining its therapeutic effect linked to D2 receptor binding. Explicit molecular dynamics simulations and end-point free energy calculations of clozapine in complex with the D2 and H1 receptors embedded in cholesterol-rich lipid bilayers were performed to analyze the intermolecular interactions and address the relevance of clozapine-functional groups. Based on that, free energy perturbation calculations were performed to measure the change in free energy of clozapine structural modifications. Our results indicate the best clozapine derivative is the iodine atom substitution for chlorine. The latter is mainly due to electrostatic interaction loss for the H1 receptor, while the halogen orientation out of the D2 active site reduces the impact on the affinity.Communicated by Ramaswamy H. Sarma.

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.

Validated Stability Indicating HPTLC Method for the Estimation of Amoxapine in Different Stress Conditions

Background:

The unstable and/or toxic degradation products may form due to degradation of drug which results into loss of therapeutic activity and lead to life threatening condition. Hence, it is important to establish the stability characteristics of drug in various conditions such as in temperature, light, oxidising agent and susceptibility across a wide range of pH values.

Introduction:

The aim of the proposed study was to develop simple, sensitive and economic stability indicating high performance thin layer chromatography (HPTLC) method for the quantification of Amoxapine in the presence of degradation products.

Methods:

Amoxapine and its degraded products were separated on precoated silica gel 60F254 TLC plates by using mobile phase comprising of methanol: toluene: ammonium acetate (6:3:1, v/v/v). The densitometric evaluation was carried out at 320 nm in reflectance/absorbance mode. The degradation products obtained as per ICH guidelines under acidic, basic and oxidative conditions have different Rf values 0.12, 0.26 and 0.6 indicating good resolution from each other and pure drug with Rf: 0.47. Amoxapine was found to be stable under neutral, thermal and photo conditions.

Results:

The method was validated as per ICH Q2 (R1) guidelines in terms of accuracy, precision, ruggedness, robustness and linearity. A good linear relationship between concentration and response (peak area and peak height) over the range of 80 ng/spot to 720 ng/spot was observed from regression analysis data showing correlation coefficient 0.991 and 0.994 for area and height, respectively. The limit of detection (LOD) and limit of quantitation (LOQ) for area were found to be 1.176 ng/mL and 3.565 ng/mL, whereas for height, 50.063 ng/mL and 151.707 ng/mL respectively.

Conclusion:

The statistical analysis confirmed the accuracy, precision and selectivity of the proposed method which can be effectively used for the analysis of amoxapine in the presence of degradation products.

Depression treatment by withdrawal of short-term low-dose antipsychotic, a proof-of-concept randomized double-blind study

BACKGROUND AND OBJECTIVE

Because increased dopamine neurotransmission occurs with most antidepressants, and because antipsychotics cause behavioural supersensitivity to dopamine, short-term low-dose antipsychotic treatment was tested on depressed patients with an expectation of clinical improvement in the supersensitive phase following drug withdrawal.

METHOD

This was a randomized, double-blind, placebo-controlled study of 48 patients who met criteria for DSM-IV(®) Major Depressive Disorder, were in a Major Depressive Episode, and had a Hamilton Depression Rating Scale (HAMD) rating of ≥14. Half the participants received 0.25mg oral haloperidol each day for 7 days, after which they received placebo daily for 4 weeks. The other half received placebo throughout the trial.

RESULTS

One week after stopping the medication, the HAMD ratings of the drug-treated patients fell by 9.96 points, as compared to a reduction of 8.73 points in the placebo-treated patients, when comparing visits 1 and 4. There was no such difference when comparing visits 2 and 4. The differences were not significant, but indicated a trend. One week after the medication was stopped, the Clinical Global Index fell 1.64±0.18 units for the medication-treated patients, compared to 1.12±0.26 units for the placebo group (P=0.05). The regimen was well tolerated.

CONCLUSIONS

Seven days of an ultra-low dose of 0.25mg haloperidol, followed by withdrawal of haloperidol, resulted in clinical depression improvement greater than placebo and significantly decreased psychomotor retardation, consistent with haloperidol-induced behavioural supersensitivity to dopamine.

LIMITATIONS

The sample was small. More patients are needed in a future study.

Almost all antipsychotics result in weight gain: a meta-analysis

Introduction

Antipsychotics (AP) induce weight gain. However, reviews and meta-analyses generally are restricted to second generation antipsychotics (SGA) and do not stratify for duration of AP use. It is hypothesised that patients gain more weight if duration of AP use is longer.

Method

A meta-analysis was conducted of clinical trials of AP that reported weight change. Outcome measures were body weight change, change in BMI and clinically relevant weight change (7% weight gain or loss). Duration of AP-use was stratified as follows: ≤6 weeks, 6–16 weeks, 16–38 weeks and >38 weeks. Forest plots stratified by AP as well as by duration of use were generated and results were summarised in figures.

Results

307 articles met inclusion criteria. The majority were AP switch studies. Almost all AP showed a degree of weight gain after prolonged use, except for amisulpride, aripiprazole and ziprasidone, for which prolonged exposure resulted in negligible weight change. The level of weight gain per AP varied from discrete to severe. Contrary to expectations, switch of AP did not result in weight loss for amisulpride, aripiprazole or ziprasidone. In AP-naive patients, weight gain was much more pronounced for all AP.

Conclusion

Given prolonged exposure, virtually all AP are associated with weight gain. The rational of switching AP to achieve weight reduction may be overrated. In AP-naive patients, weight gain is more pronounced.

Structural contributions of antipsychotic drugs to their therapeutic profiles and metabolic side effects

Antipsychotic drugs have various neuropharmacological properties as a result of their structural diversity. Despite their therapeutic benefits, most of the prescribed atypical antipsychotics can induce severe side effects, including weight gain, type II diabetes mellitus, and cardiovascular diseases. Among the developed atypical antipsychotic agents, tetracyclic dibenzodiazepine and thienobenzodiazepine compounds, particularly clozapine and olanzapine, are associated with the greatest weight gain and metabolic disturbances. However, the unique chemical structure of these compounds causes the low risk of side effects reported for typical antipsychotics (e.g. extrapyramidal symptoms and tardive dyskinesia). This report reviews the recent discovery of the potential role of the chemical structure of antipsychotics in their therapeutic properties and metabolic disturbances. By developing structure-activity relationship studies for atypical antipsychotics, we will improve our understanding of the structural modifications of these chemical classes that lead to reduced weight gain, which will be an invaluable step toward the discovery of the next generation of atypical antipsychotics. In this review, we suggest that a novel dibenzodiazepine or thienobenzodiazepine antipsychotic drug with lower affinity for H(1) receptors may significantly advance schizophrenia therapy.

Amoxapine as an antipsychotic: comparative study versus haloperidol

It has been proposed that the lack of extrapyramidal side effects of atypical antipsychotic drugs is caused by their fast dissociation or low affinity for the D2 receptor or their concomitant high affinity for other receptors, for example, 5HT2 and D4. We noted that amoxapine, an established antidepressant, has affinity for 5HT2 and D2 receptors, and its effects in preclinical model are very similar to atypical antipsychotics. The objective of this study was to examine the antipsychotic effect and side effect profile of amoxapine versus haloperidol in a double-blind study for 6 weeks in patients with schizophrenia. A total of 54 patients with schizophrenia were titrated to the starting dose of 150 mg/d of amoxapine or 5 mg/d of haloperidol within 3 days. Clinical efficacy and side effects were monitored at baseline, and Weeks 2, 4, and 6.Forty-one patients completed 5 weeks, and 36 patients completed the 6 weeks of follow-up. Both treatment groups showed significant improvement in Positive and Negative Syndrome Scale positive (30%) and total scores (20%), without significant differences between the groups. In addition, in the amoxapine group, significant improvement was seen in the negative symptoms and the Clinical Global Impression. No significant changes were seen on Calgary Depression Scale for Schizophrenia, side effect checklists, and prolactin levels in both groups. The results suggest that amoxapine may be as effective an antipsychotic as haloperidol as predicted by its affinity for D2 and 5HT2 receptors, supporting earlier studies. However, it did not prove to have fewer extrapyramidal side effects than haloperidol, possibly because the baseline scores were very low.

Amoxapine as an atypical antipsychotic: a comparative study vs risperidone

Amoxapine is marketed as an antidepressant. However, its in-vitro profile, receptor occupancy and preclinical effects are very similar to atypical antipsychotics. Amoxapine has also shown efficacy as an atypical antipsychotic in open trials. The objective of this study was to compare the antipsychotic and side effect profile of amoxapine and risperidone in a randomised assignment, standardized dosing, double-blind trial of acutely psychotic patients with schizophrenia. A total of 48 schizophrenic patients were enrolled and randomized in a double-blind 6-week trial to receive either risperidone (up to 5 mg/day) or amoxapine (up to 250 mg/day). Positive, negative, affective symptoms and motor side effects were measured using standardized weekly assessments. Prolactin levels were also determined at baseline and at the end of the study. A total of 39 patients (amoxapine, n=22; risperidone, n=21) completed the trial. Both pharmacological treatments, amoxapine 228.0 mg/day (SD=34.6) and risperidone 4.5 mg/day (SD=0.7), showed equivalent improvement in positive, negative, and depressive symptoms. Amoxapine was associated with less EPS and less prolactin elevation than risperidone. These data support previous reports about the efficacy of amoxapine as an atypical antipsychotic. Since amoxapine is off-patent, it may be a valuable low-cost alternative to new atypical antipsychotics, particularly in low-income countries where the majority of the patients are still treated with typical antipsychotics.

Survey on schizophrenia treatment in Mexico: perception and antipsychotic prescription patterns

BACKGROUND

Since the introduction of antipsychotics, especially the so called atypicals, the treatment of schizophrenia has shown important improvements. At the present time, it is preferred to label clozapine and other antipsychotics sharing similar profiles as second-generation antipsychotics (SGAs). These medications have been proposed by some experts as a first line treatment for schizophrenia. It is critical to have reliable data about antipsychotic prescription in Mexico and to create management guidelines based on expert meetings and not only on studies carried out by the pharmaceutical industry. Only this approach will help to make the right decisions for the treatment of schizophrenia.

METHODS

A translated version of Rabinowitz's survey was used to evaluate antipsychotic prescription preferences and patterns in Mexican psychiatrists. The survey questionnaire was sent by mail to 200 psychiatrists from public institutions and private practice in Mexico City and Guadalajara, Mexico.

RESULTS

Recommendations for antipsychotics daily doses at different stages of the treatment of schizophrenia varied widely. Haloperidol was considered as the first choice for the treatment of positive symptoms. On the contrary, risperidone was the first option for negative symptoms. For a patient with a high susceptibility for developing extrapyramidal symptoms (EPS), risperidone was the first choice. It was also considered that SGAs had advantages over typical antipsychotics in the management of negative symptoms, cognitive impairment and fewer EPS.Besides, there was a clear tendency for prescribing typical antipsychotics at higher doses than recommended and inadequate doses for the atypical ones.

CONCLUSIONS

Some of the obstacles for the prescription of SGAs include their high cost, deficient knowledge about their indications and dosage, the perception of their being less efficient for the treatment of positive symptoms and the resistance of some Mexican physicians to change their prescription pattern. It is necessary to reach a consensus, in order to establish and standardize the treatment of schizophrenia, based on the information reported in clinical trials and prevailing economic conditions in Mexico.