Clozapine fails to prevent the development of haloperidol-induced behavioral hypersensitivity in a cotreatment paradigm

Switching a combination of first- and second-generation antipsychotic polypharmacy to antipsychotic monotherapy in long-term inpatients with schizophrenia and related disorders. The SwAP trial II: Results on side effects

OBJECTIVE

This study examined the effects of switching antipsychotic polypharmacy (APP) to antipsychotic monotherapy (APM) on various side effects in inpatients with schizophrenia. Side effects of interest included psychic, autonomic, and sexual symptoms, as well as metabolic side effects and movement disorders.

METHOD

A 9-month parallel randomized open-label clinical trial was conducted involving 136 chronic inpatients from two psychiatric hospitals in the Netherlands. Participants were randomly assigned to either a STAY or a SWITCH group. The SWITCH group underwent a 3-month tapering-off period in which either first-generation or second-generation antipsychotic medication was discontinued, followed by APM. Patients were assessed at baseline and at follow-up assessments at 3, 6, and 9 months. Psychic, neurological, autonomic, and sexual side effects were evaluated using the UKU Rating Scale, while movement disorders were measured with the St. Hans Rating Scale. Various metabolic parameters were also recorded.

RESULTS

In the STAY group, side effects remained generally stable over time, except for a slight reduction in sexual desire. In contrast, the SWITCH group experienced significant reductions in psychic and autonomic symptoms, as well as improvements in akathisia, parkinsonism, and dyskinesia. There were no changes in dystonia, paresthesia, epilepsy, or sexual symptoms for this group. Notably, the SWITCH group also showed significant reductions in BMI and body weight.

CONCLUSION

Switching APP to APM in long-term inpatients reduces the severity of various side effects, including movement disorders and metabolic side effects.

Mechanism of action of clozapine-induced modification of motor behavior in an animal model of the "super-off" phenomenon

We tested the effects of clozapine, and "atypical" neuroleptic with high affinity for the D4 (dopaminergic), and the 5-HT1c and 5-HT2 (serotonergic) receptor subtypes on locomotor activity in an animal model of Parkinson's disease showing a bimodal response curve to increasing doses of a D2 agonist. Sulpiride (D2 antagonist) and ritanserin (5-HT1c and 5-HT2 antagonist) were used for comparison. The D1 agonist SKF 38393 at a dose of 8 mg/kg significantly reversed the akinesia induced by chronic reserpine treatment (1 mg/kg for 5 days) and alpha-methyl-p-tyrosine pretreatment (300 mg/kg). In this model, the addition of a low dose of a D2 agonist, LY 171555 (quinpirole, 1 microgram/kg), inhibited the effects of SKF 38393, whereas the same drug at higher doses (5-50 microgram/kg) restored and potentiated the stimulatory response to D1 stimulation. Clozapine inhibited the inhibitory phase and potentiated the stimulatory phase of the curve. Sulpiride inhibited both phases of the dose-response curve (inhibitory/stimulatory), whereas ritanserin had no effect. We believe these results may reflect a disinhibition phenomenon possible mediated by the blockade by clozapine of a subpopulation of inhibitory, dopamine (DA) receptors belonging to the D2 "family."

Alterations in striatal neurotrophic activity induced by dopaminergic drugs

The administration of dopaminergic drugs induces a variety of compensatory responses ostensibly designed to reinstate normal dopamine (DA) tone. We have hypothesized that drug-induced alterations in striatal-derived neurotrophic activity contributes to these compensatory processes. This phenomenon has been studied by examining the growth of mesencephalic cultures incubated with cell-free extracts of striatal tissue taken from patients or rats treated with various drugs. Our results reveal that reducing striatal DA tone by administering the DA antagonist haloperidol, the DA neurotoxin 6-hydroxydopamine, or as occurs naturally in Parkinson's disease, increases striatal trophic activity. Conversely, increasing striatal DA tone by administering the indirect DA agonists amphetamine or levodopa reduces trophic activity in the striatum. Kainic acid lesions of the striatum similarly reduce this trophic activity. The implications of these drug-induced alterations in trophic activity are discussed and reviewed.