Relationships between clinical and biochemical effects of melperone and thiothixene in psychotic women

Optimisation of pharmacotherapy in psychiatry through therapeutic drug monitoring, molecular brain imaging and pharmacogenetic tests: focus on antipsychotics

BACKGROUND

For psychotic disorders (i.e. schizophrenia), pharmacotherapy plays a key role in controlling acute and long-term symptoms. To find the optimal individual dose and dosage strategy, specialized tools are used. Three tools have been proven useful to personalize drug treatments: therapeutic drug monitoring (TDM) of drug levels, pharmacogenetic testing (PG), and molecular neuroimaging.

METHODS

In these Guidelines, we provide an in-depth review of pharmacokinetics, pharmacodynamics, and pharmacogenetics for 50 antipsychotics. Over 30 international experts in psychiatry selected studies that have measured drug concentrations in the blood (TDM), gene polymorphisms of enzymes involved in drug metabolism, or receptor/transporter occupancies in the brain (positron emission tomography (PET)).

RESULTS

Study results strongly support the use of TDM and the cytochrome P450 (CYP) genotyping and/or phenotyping to guide drug therapies. Evidence-based target ranges are available for titrating drug doses that are often supported by PET findings.

CONCLUSION

All three tools discussed in these Guidelines are essential for drug treatment. TDM goes well beyond typical indications such as unclear compliance and polypharmacy. Despite its enormous potential to optimize treatment effects, minimize side effects and ultimately reduce the global burden of diseases, personalized drug treatment has not yet become the standard of care in psychiatry.

Secondary parkinsonism due to drugs, vascular lesions, tumors, trauma, and other insults

In addition to neurodegenerative disorders, there are many secondary forms of parkinsonism. The most common cause for secondary parkinsonism is the intake of distinct drugs. Neuroleptics and calcium channel blockers have been mainly described to induce parkinsonism, but also other drugs were suspected to cause or worsen parkinsonism. Another common cause for secondary parkinsonism are vascular lesions (i.e. vascular parkinsonism). Furthermore, also brain tumors have been described as rare causes for parkinsonism. Moreover, parkinsonism can be caused by chronic traumatic encephalopathy, which is a special case, since secondary insults to the brain leads to the occurrence of a neuropathologically defined disease. Other rare causes for secondary parkinsonism are lesions caused by infectious or immunological diseases as well as toxins or street drugs.

Melperone in treatment-refractory schizophrenia: a case series

OBJECTIVE

Clozapine is the treatment of choice in refractory schizophrenia, but a substantial proportion of patients experience inadequate response or tolerate the drug poorly. Melperone has been suggested as a possible alternative in such patients. This case series examines the efficacy of melperone in refractory schizophrenia.

METHOD

All patients prescribed melperone at the South London and Maudsley NHS Foundation Trust were identified using a pharmacy database. The main outcome was to determine the proportion of patients discharged on melperone.

RESULTS

Three of 21 patients were discharged on melperone. The primary reason for discontinuation was lack of efficacy.

CONCLUSION

Melperone may be an option in a very few patients with refractory schizophrenia, but it should not be considered as an alternative to clozapine.

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.

Melperone in the treatment of neuroleptic-resistant schizophrenia

Melperone is an effective antipsychotic drug that has been reported to have atypical properties, i.e. low extrapyramidal side effect liability at clinically effective doses. It also does not increase serum prolactin levels. Its effectiveness for patients with neuroleptic (treatment)-resistant schizophrenia has not been evaluated. In this study, melperone was administered, in an open trial design of 6 weeks' duration, to 44 patients with chronic neuroleptic-resistant schizophrenia. The Global Assessment Scale (GAS), Brief Psychiatric Rating Scale (BPRS) and measures of extrapyramidal symptoms and other clinical variables were assessed at baseline and 6 weeks. Thirty-seven patients completed the 6-week trial. Melperone significantly improved overall psychiatric status as measured by GAS score for all evaluable subjects [last value carried forward (LVCF) and a completers analysis]. No significant effects on BPRS measures of psychopathology scores were found in the LVCF or completers analysis. Patients who showed > or = 20% decrease in the BPRS Total score (N=7) were more likely to have high baseline psychopathology, as measured by BPRS Total and Anxiety-Depression subscales, than those who showed > or = 20% increase in the BPRS Total score (N=8). Non-responders to melperone generally did not respond to subsequent treatment with clozapine, indicating that this group of patients was very treatment resistant. Melperone was not associated with worsening of extrapyramidal symptoms, elevation in plasma prolactin levels, or an increase in body mass index (BMI). The results suggest that a proportion of neuroleptic-resistant patients with schizophrenia respond to melperone, which requires further controlled study.

The effects of raclopride on vacuous jaw movements in rats following acute administration

Classic neuroleptics produce a syndrome of vacuous jaw movements in rats, whereas atypical neuroleptics like clozapine do not. The present study compared the effects of repeated administration of raclopride, clozapine, haloperidol, or vehicle on vacuous jaw movements in rats over a 4-week period. Rats received an IP injection of drug once a day. On days 1, 8, 15, and 29 the rats were observed for a 5-min period by two trained observers who recorded their vacuous jaw movements. The dose-response curves at which each drug produced vacuous jaw movements are presented and discussed in terms of their predictive capabilities of early onset extrapyramidal side effects.

Dopamine D4 versus D2 receptor selectivity of dopamine receptor antagonists: possible therapeutic implications

The dopamine D4 receptor, which is considered a close variant of the dopamine D2 receptor, has recently been cloned. Receptor binding studies demonstrated that clozapine, which is an effective antipsychotic agent but atypical in that it lacks the usual side effects of other antipsychotic agents, has high selectivity for the dopamine D4 receptor versus the dopamine D2 receptor. Comparative binding affinity studies have been carried out for a number of interesting dopaminergic agents using membranes prepared from cloned dopamine D2 and D4 receptor containing cells. It was found that clozapine is selective for the dopamine D4 vs. the D2 receptor by a factor of 2.8. Other compounds with dopamine D4 receptor selectivity were (+)-apomorphine (8.7), (+)-N-propyl-norapomorphine (NPA) (2.4) and melperone (1.3). Compounds with considerable selectivity for the dopamine D2 receptor were haloperidol (0.31), chlorpromazine (0.084), trifluoperazine (0.034) and raclopride (0.001). Overall, the results with the antipsychotic agents tested, support the concept that dopamine D4 receptor selectivity may confer clozapine-like antipsychotic efficacy and furthermore that dopamine D2 receptor selectivity may confer side effect liability (extrapyramidal side effects and tardive dyskinesia).

Chronic melperone administration does not enhance oral movements in rats

Melperone and haloperidol were compared in a rat model for tardive dyskinesia. Drugs were given chronically for 12 months with the drinking water and the frequency of oral movements was measured at monthly intervals. Haloperidol (0.2 and 0.4 mg/kg/d) produced an increase in vacuous chewing movements, whereas melperone (2.4, 5.1 and 11.0 mg/kg/d) did not differ from untreated controls.

Clozapine: new research on efficacy and mechanism of action

Clozapine can produce greater clinical improvement in both positive and negative symptoms than typical antipsychotic drugs in neuroleptic-resistant schizophrenic patients. The clinical response may occur rapidly in some patients but is delayed in others. Clozapine has also been reported to produce fewer parkinsonian symptoms, to involve a lower risk of producing tardive dyskinesia, and to produce no serum prolactin elevations in man. It seems likely that these effects are the result of a common biological mechanism or related mechanisms, rather than unrelated effects. Other atypical antipsychotic drugs, such as melperone and fluperlapine, share at least some of these properties. A relatively low affinity for the D-2 dopamine (DA) receptor and high affinity for the 5-HT2 receptor, producing a high 5-HT2/D-2 ratio, best distinguishes atypical antipsychotics like clozapine from typical antipsychotic drugs. Through its weak antagonist action on D-2DA receptors and a potent inhibitory effect on 5-HT2 receptors, as well as its ability to increase DA and 5-HT2 release, clozapine may be able to permit more normal dopaminergic function in the anterior pituitary, the mesostriatal, mesolimbic and mesocortical regions. The numerous advantages of clozapine over typical neuroleptics are consistent with the primary importance of DA to the pathophysiology of schizophrenia. The secondary but still significant role of 5-HT in the action of clozapine may either be direct or via the effect of 5-HT on dopaminergic mechanisms. Some aspects of schizophrenia could be due to a dysregulation of the interaction between serotonergic and dopaminergic neurotransmission.

Antagonism of serotonin receptor mediated neuroendocrine and temperature responses by atypical neuroleptics in the rat

The ability of atypical and typical antipsychotics to antagonize serotonin (5-HT) receptor-mediated temperature and neuroendocrine responses was tested in rats. Clozapine, melperone and setoperone, three atypical neuroleptics, blocked in a dose-dependent manner, the hyperthermic response to the 5-HT agonist, MK-212, whereas chlorpromazine and haloperidol were ineffective. The hypothermic response to the 5-HT1A agonist, 8-OH-DPAT, was unaltered by any of the atypical neuroleptics tested. Similarly, MK-212-induced corticosterone secretion was blocked in a dose-related manner by clozapine, melperone and setoperone but was relatively unaffected by either haloperidol or chlorpromazine. The increase in corticosterone secretion observed following 8-OH-DPAT administration was not attenuated by pretreatment with the atypical or typical antipsychotics tested. These data indicate that atypical neuroleptics are effective 5-HT2 but not 5-HT1A antagonists in vivo. Conversely, the typical neuroleptics, haloperidol and chlorpromazine do not block the 5-HT receptors involved in activation of the hypothalamic-pituitary-adrenal axis or thermoregulation.

Differential effects of haloperidol, clozapine, and fluperlapine on tuberoinfundibular dopamine neurons and prolactin secretion in the rat

Two atypical neuroleptic agents, clozapine and fluperlapine, produced rapid elevations in plasma PRL concentrations that were similar in magnitude to those produced by haloperidol. However, the PRL response to clozapine or fluperlapine was of much shorter duration than that elicited by haloperidol. Clozapine, but neither fluperlapine nor haloperidol, produced a rapid increase in the activity of tuberoinfundibular dopamine (TIDA) neurons, as evidenced by an enhanced accumulation of dihydroxyphenylalanine (DOPA) in the median eminence after the inhibition of DOPA decarboxylase. The clozapine-induced increase in DOPA accumulation was evident within 30 minutes after its administration and persisted for at least 4 hours. The clozapine-induced increase in the activity of TIDA neurons may account, in part, for the abbreviated PRL response to this neuroleptic. In addition, ability to produce a short-lived increase in PRL secretion in the rat appears to be common to the atypical neuroleptic drugs.

Monoamines and monoamine metabolites in brains from demented schizophrenics

The brains from 12 schizophrenic patients were investigated post-mortem for their content of noradrenaline (NA), dopamine (DA), 5-hydroxytryptamine (5-HT), homovanillic acid (HVA), and 5-hydroxyindolacetic acid (5-HIAA). Six of the schizophrenics had been lobotomized 25--30 years prior to death. A control group matched for age was collected in the autopsy room. The concentrations of NA, DA, and HVA in different parts of the brain from the schizophrenic group did not differ from those of the controls. 5-HT was determined in 11 nuclei or areas of the brain. The schizophrenic group had lower mean values compared with the controls, and in the hypothalamus, medulla oblongata, and hippocampus the difference was at a significant level. 5-HIAA was determined in six areas of the brain but only in a few cases. There was a trend towards lower means of 5-HIAA in the schizophrenics. Cause of death, medication, food intake, age, time between death and autopsy, time the corpses have lain in room temperature, and dissection technique are discussed in relation to these findings. These variables have to be kept under careful control before changes can be claimed as having pathogenetic importance for schizophrenia or for the progressing dementia in this disease.