Clinical melperone treatment blocks D2-dopamine receptors in the human brain as determined by PET

Beyond monoamines: II. Novel applications for PET imaging in psychiatric disorders

Early applications of positron emission tomography (PET) in psychiatry sought to identify derangements of cerebral blood flow and metabolism. The need for more specific neurochemical imaging probes was soon evident, and these probes initially targeted the sites of action of neuroleptic (dopamine D₂ receptors) and psychoactive (serotonin receptors) drugs. For nearly 30 years, the centrality of monoamine dysfunction in psychiatric disorders drove the development of an armamentarium of monoaminergic PET radiopharmaceuticals and imaging methodologies. However, continued investments in monoamine-enhancing drug development realized only modest gains in efficacy and tolerability. As patent protection for many widely prescribed and profitable psychiatric drugs lapsed, drug development pipelines shifted away from monoamines in search of novel targets with the promises of improved efficacy, or abandoned altogether. Over this period, PET radiopharmaceutical development activities closely parallelled drug development priorities, resulting in the development of new PET imaging agents for non-monoamine targets. In part two of this review, we survey clinical research studies using the novel targets and radiotracers described in part one across major psychiatric application areas such as substance use disorders, anxiety disorders, eating disorders, personality disorders, mood disorders, and schizophrenia. Important limitations of the studies described are discussed, as well as key methodologic issues, challenges to the field, and the status of clinical trials seeking to exploit these targets for novel therapeutics.

Auditing clinical outcomes after introducing off-licence prescribing of atypical antipsychotic melperone for patients with treatment refractory schizophrenia

Aims and Method. To evaluate the practical utility of off-licence prescribing and clinical outcomes of treatment with atypical antipsychotic Melperone. Method: Prospective data collection on patient's clinical characteristics and outcomes. Results. 17 patients with a diagnosis of refractory schizophrenia were identified as suitable for off-license prescribing of Melperone and commenced treatment (13 were previously treated with Clozapine). Seven of those currently remain on Melperone (41%), and for six patents, the BPRS symptom scores reduced significantly over time (24–61%) additionally patients displayed improvements of their quality of life. Six patients were discontinued due to noncompliance and/or side effects. Melperone was ineffective in the other four patients. Clinical Implications. The example of a small group of patients responding well to a comparably safe and inexpensive atypical antipsychotic with favourable side effect profile should encourage clinicians to use this tool as third-line treatment and to conduct more systematic clinical research.

Melperone, an aytpical antipsychotic drug with clozapine-like effect on plasma prolactin: contrast with typical neuroleptics

OBJECTIVE

To evaluate the effect of melperone, a butyrophenone with atypical antipsychotic properties, on plasma prolactin (PRL) concentrations compared with clozapine and typical neuroleptics.

METHODS

Analysis of pre- and post-treatment PRL levels collected prospectively per protocol in a non-randomized study of 26 melperone-, 76 clozapine-, and 66 neuroleptic-treated patients with schizophrenia or schizoaffective disorder. Cross-sectional analysis of a larger sample of patients with PRL data was also performed.

RESULTS

For males, post-treatment PRL levels were significantly higher in the typical neuroleptic group compared with the melperone (p = 0.0001) and clozapine (p = 0.0001) groups, with no significant difference between clozapine and melperone. For females, post-treatment PRL levels were significantly higher in the melperone group as compared to the clozapine group (p = 0.004). There were too few typical neuroleptic-treated females to permit analysis of this sample. However, the cross-sectional analysis of PRL data confirmed the results for melperone- and clozapine-treated females, and showed higher PRL levels in typical neuroleptic-treated females as compared with those who received melperone and clozapine.

CONCLUSION

Melperone did not significantly increase PRL levels in male patients. However, melperone and typical neuroleptics caused increase in PRL levels in females. Further study of melperone's effects on PRL concentration is warranted.

A comparison of two doses of melperone, an atypical antipsychotic drug, in the treatment of schizophrenia

Melperone at a dose of 300 mg/day has been reported to be as effective as thiothixene and superior to placebo in the treatment of schizophrenia. Limited ability to cause extrapyramidal side effects (EPS) and absence of an effect on plasma prolactin (pPRL) levels suggests that it is an atypical antipsychotic drug. The goal of this pilot study was to determine: (1). the ability of melperone 400 mg/day to produce greater improvement in psychopathology than melperone 100 mg/day; and (2). to compare side effects of these two doses of melperone. Melperone, 100 or 400 mg/day, was administered to 34 acutely hospitalized patients with schizophrenia for 6 weeks in a randomized, double-blind manner. Psychopathology, EPS, pPRL levels, and body mass index (BMI) were evaluated at baseline and 6 weeks. Twenty-seven completed the 6-week treatment. A last carried forward analysis revealed no significant difference in the ability of the two doses of melperone to improve psychopathology as measured by the Brief Psychiatric Rating Scale (BPRS)-Total and Positive subscale, the Scale for the Assessment of Negative Symptoms (SANS), the Schedule for Affective Disorders and Schizophrenia-Disorganization subscale, and the Global Assessment Scale (GAS). Treatment with melperone was not associated with exacerbation of EPS, or an increase in pPRL levels or BMI. The Abnormal Involuntary Movement Scale (AIMS) was not significantly changed by treatment with melperone. These results suggest that melperone was equally effective at doses 100 and 400 mg/day, for ameliorating psychopathology and improving overall psychiatric status in patients with schizophrenia. However, the lack of difference and a placebo control group, as well as modest degrees of change in psychopathology, require caution about assuming efficacy of either dose. The lack of significant side effects such as exacerbation of EPS, pPRL elevation, and weight gain indicates melperone is well tolerated.