Differential effects of AMPA receptor potentiators and glycine reuptake inhibitors on antipsychotic efficacy and prefrontal glutamatergic transmission.

RATIONALE: The α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor positive allosteric modulators (AMPA-PAMs), Org 24448 and Org 26576, and the glycine transporter-1 (GlyT-1) inhibitor Org 25935 are developed for treatment of schizophrenia. OBJECTIVES: Here we examined experimentally the ability of co-administration of these AMPA-PAMs or the GlyT-1 inhibitor to augment the antipsychotic activity and effect on cortical N-methyl-D: -aspartate (NMDA) receptor-mediated transmission of risperidone, olanzapine, or haloperidol. METHODS: We examined antipsychotic efficacy using the conditioned avoidance response (CAR) test, extrapyramidal side effect liability using a catalepsy test, and cortical NMDA receptor-mediated glutamatergic transmission using intracellular electrophysiological recording technique in vitro. RESULTS: Both AMPA-PAMs enhanced the suppression of CAR induced by risperidone or olanzapine, and Org 24448 also enhanced the effect of haloperidol. In contrast, the GlyT-1 inhibitor did not cause any behaviorally significant effect in the CAR test. However, the GlyT-1 inhibitor, but not the AMPA-PAMs, produced a large facilitation of NMDA-induced currents. All three drugs potentiated the effect of risperidone but not haloperidol on these currents. The GlyT-1 inhibitor also facilitated the effect of olanzapine. All drugs potentiated the effect of risperidone on electrically stimulated excitatory postsynaptic potentials (EPSP) in cortical pyramidal cells, whereas only the GlyT inhibitor facilitated the effect of olanzapine. CONCLUSIONS: Our results suggest that the AMPA-PAMs, when compared to the GlyT-1 inhibitor, show differential effects in terms of augmentation of antipsychotic efficacy, particularly when combined with risperidone or olanzapine. Both AMPA-PAMs and the GlyT-1 inhibitor may also improve negative symptoms and cognitive impairments in schizophrenia, in particular when combined with risperidone.

Blood lactate levels in patients receiving first- or second- generation antipsychotics.

AIM: To compare the blood lactate levels between patients with psychotic disorder receiving first- and those receiving second-generation antipsychotics. METHODS: The study was conducted at the psychiatric inpatient and outpatient clinics of the Split Clinical Hospital from June 6, 2008 to October 10, 2009. Sixty patients with psychotic disorder who were assigned to 6-month treatment were divided in two groups: 30 received haloperidol (first generation antipsychotic) and 30 received olanzapine (second generation antipsychotic). Blood lactate levels, other metabolic parameters, and scores on the extrapyramidal symptom rating scale were assessed. RESULTS: Patients receiving haloperidol had significantly higher blood lactate levels than patients receiving olanzapine (P < 0.001). They also more frequently had parkinsonism, which was significantly correlated with both haloperidol treatment at 1 month (P < 0.001) and 6 months (P = 0.016) and olanzapine treatment at baseline (P = 0.016), 3 months (P = 0.019), and 6 months (P = 0.021). Also, patients receiving haloperidol had significant correlation between blood lactate and dystonia at 1 month (P < 0.001) and 6 months (P = 0.012) and tardive dyskinesia at 1 month (P = 0.032). There was a significant difference between the treatment groups in lactate levels at all points from baseline to month 6 (P < 0.001). CONCLUSION: It is important to be aware of the potential effect of haloperidol treatment on increase in blood lactate levels and occurrence of extrapyramidal side effects. Therefore, alternative antipsychotics should be prescribed with lower risk of adverse side effects.

Pimozide augmentation of clozapine inpatients with schizophrenia and schizoaffective disorder unresponsive to clozapine monotherapy.

Despite its superior efficacy, clozapine is helpful in only a subset of patients with schizophrenia unresponsive to other antipsychotics. This lack of complete success has prompted the frequent use of various clozapine combination strategies despite a paucity of evidence from randomized controlled trials supporting their efficacy. Pimozide, a diphenylbutylpiperidine, possesses pharmacological and clinical properties distinct from other typical antipsychotics. An open-label trial of pimozide adjunctive treatment to clozapine provided promising pilot data in support of a larger controlled trial. Therefore, we conducted a double-blind, placebo-controlled, parallel-designed 12-week trial of pimozide adjunctive treatment added to ongoing optimal clozapine treatment in 53 patients with schizophrenia and schizoaffective disorder partially or completely unresponsive to clozapine monotherapy. An average dose of 6.48 mg/day of pimozide was found to be no better than placebo in combination with clozapine at reducing Positive and Negative Syndrome Scale total, positive, negative, and general psychopathology scores. There is no suggestion from this rigorously conducted trial to suggest that pimozide is an effective augmenting agent if an optimal clozapine trial is ineffective. However, given the lack of evidence to guide clinicians and patients when clozapine does not work well, more controlled trials of innovative strategies are warranted.

Molecular mechanisms underlying synergistic effects of SSRI-antipsychotic augmentation in treatment of negative symptoms in schizophrenia.

Negative symptoms in schizophrenia respond poorly to antipsychotics, but may improve when these are augmented with selective serotonin reuptake inhibitors (SSRIs). The molecular mechanisms underlying the augmentation are unclear. Nevertheless, significant progress has been made, pointing to some candidate systems which may be involved in SSRI-antipsychotic synergism. Thus, the enhanced dopamine release by SSRI-antipsychotic treatment is modulated by specific serotonergic receptors and by tyrosine hydroxylase. There are modifications in gamma-aminobutyric acid system via glutamate decarboxylase 67, protein kinase C beta and the receptor for activated C-kinase 1 (Rack1). Some studies indicate the input of transcription and neurotrophic factors as phospho-cyclic adenosine monophosphate response element-binding protein, Fos and fibroblast growth factor-2. Alterations in calcium signaling (neurogranin, regulator of G-protein signaling and Rack1) and in cytokine receptors for interleukin-8 and chemokine have also been reported. While as yet limited in scope, the evidence suggests definable molecular targets which may be implicated in drug development based on SSRI-antipsychotic synergistic actions.

Agitation and/or aggression after traumatic brain injury in the pediatric population treated with ziprasidone. Clinical article.

OBJECT: Agitation and aggression are common after traumatic brain injury (TBI) and can hamper recovery and rehabilitative efforts. To date, there is no consensus on pharmaceutical intervention for these conditions after TBI. Ziprasidone has been reported efficacious in this population but the evidence is limited. The authors report their experience of using ziprasidone to treat posttraumatic brain injury agitation in 20 consecutive pediatric patients. A secondary objective of this case series was to attempt to establish an age-specific dosage and identify possible side effects of this medication. METHODS: This case series study was performed at a university hospital and pediatric trauma center. Over an 18-month period, all patients who presented to the pediatric intensive care unit with TBI and later developed agitation and/or aggression were treated with ziprasidone as the sole intervention. Pre- and posttreatment scores on the Riker Sedation-Agitation Scale (SAS) were recorded along with demographic data. RESULTS: Twenty children received ziprasidone for agitation and/or aggression during the immediate recovery period from TBI. The median patient age was 8 years (range 9 months-17 years). Children were stratified into 4 age groups: <2 years old (Group 1), 2-6 years old (Group 2), 7-12 years old (Group 3), and >or=13 years old (Group 4). The SAS score, before and 24 hours after the initiation of ziprasidone, demonstrated a significant reduction after initiation of the medication (p<0.001). The initial dose for Groups 1-4 was 1.7, 0.9, 0.7, and 0.6 mg/kg, respectively, with final doses of 1.8, 1.5, 1.7, and 0.07 mg/kg, respectively. The duration of therapy for Groups 1-4 was 5, 8, 6, and 3 days, respectively. All patients received continuous cardiac and blood-pressure monitoring. No adverse events were reported in any of the age groups. CONCLUSIONS: Based on this limited patient series, ziprasidone appears to be safe and effective in pediatric patients with closed head injuries who develop agitation and/or aggression in the immediate postinjury period. Ziprasidone consistently lowered SAS scores and did so in all age groups. There were minimal dose adjustments and the duration of therapy was relatively brief. No adverse events were reported. A prospective trial of ziprasidone in this population appears warranted.

The impact of calories and fat content of meals on oral ziprasidone absorption: a randomized, open-label, crossover trial.

BACKGROUND: Food is known to increase the bioavailability of ziprasidone. Therefore, we evaluated the effects of meals of differing caloric and fat content on steady-state ziprasidone exposure in a stable, treated group of subjects with DSM-IV diagnoses of schizophrenia, schizoaffective disorder, bipolar disorder, or psychotic disorder (not otherwise specified) who were already receiving oral ziprasidone as their standard therapy. METHOD: Patients took ziprasidone under 6 meal conditions in randomized sequences (fasted, low calorie/low fat, low calorie/high fat, medium calorie/high fat, high calorie/low fat, and high calorie/high fat); each crossover period was separated by at least 3 days for washout of the previous meal condition. Serial blood samples were obtained over the 12 hours postdose. The study was conducted from July 27 to September 28 of 2006. RESULTS: Maximum ziprasidone exposures in this study were observed with high-calorie meals (1000 kcal), which were nearly twice those observed under fasting conditions. The medium-calorie meal (500 kcal) was associated with exposures similar to the high-calorie meals. Low-calorie meals (250 kcal) were associated with exposures that were approximately 60% to 90% lower than those of medium- and high-calorie meals, and approached exposures seen under fasting conditions. Fat content of the meal had no significant effect on ziprasidone absorption. The ziprasidone exposures observed with medium- and high-calorie meals had less variability than those with low-calorie meals and under fasting conditions. CONCLUSIONS: These results confirm that ziprasidone should be taken with food and that a meal equal to or greater than 500 kcal, irrespective of fat content, is required for optimal and reproducible bioavailability of the administered dose.

Effects of topiramate on the prepulse inhibition of the acoustic startle in rats.

The anticonvulsant topiramate (TPM) has been recently proposed as a novel adjuvant therapy for bipolar disorder and schizophrenia, yet its efficacy remains controversial. As both disorders are characterized by gating deficits, we tested the effects of TPM on the behavioral paradigm of prepulse inhibition (PPI) of the acoustic startle response, a validated animal model of sensorimotor gating. TPM (10, 18, 32, 58, 100 mg/kg, intraperitoneal, i.p.) enhanced PPI in rats in a dose-dependent fashion, prevented the PPI reduction mediated by the dopaminergic agonist apomorphine (0.25 mg/kg, subcutaneous, s.c.) and potentiated the effects of the antipsychotic drugs haloperidol (0.05, 0.1 mg/kg, i.p.) and clozapine (2.5, 5 mg/kg, i.p.). Conversely, TPM elicited no significant effect on the PPI disruption mediated by the NMDA receptor antagonist dizocilpine (0.05, 0.1 mg/kg, s.c.) and surprisingly antagonized the attenuation of dizocilpine-induced PPI disruption mediated by clozapine (5 mg/kg, i.p.). Our results suggest that TPM may exert diverse actions on the neural substrates of sensorimotor gating. While the pharmacological mechanisms of such effects are still elusive, our findings might contribute to shed light on some controversies on the therapeutic action of TPM, and point to this drug as a putative novel adjuvant therapy for some clusters of gating disturbances.