Double-blind olanzapine vs. haloperidol D2 dopamine receptor blockade in schizophrenic patients: a baseline-endpoint

Novel drug treatments for pain in advanced cancer and serious illness: a focus on neuropathic pain and chemotherapy-induced peripheral neuropathy

Drugs that are commercially available but have novel mechanisms of action should be explored as analgesics. This review will discuss haloperidol, miragabalin, palmitoylethanolamide (PEA), and clonidine as adjuvant analgesics or analgesics. Haloperidol is a sigma-1 receptor antagonist. Under stress and neuropathic injury, sigma-1 receptors act as a chaperone protein, which downmodulates opioid receptor activities and opens several ion channels. Clinically, there is only low-grade evidence that haloperidol improves pain when combined with morphine, methadone, or tramadol in patients who have cancer, pain from fibrosis, radiation necrosis, or neuropathic pain. Miragabalin is a gabapentinoid approved for the treatment of neuropathic pain in Japan since 2019. In randomized trials, patients with diabetic neuropathy have responded to miragabalin. Its long binding half-life on the calcium channel subunit may provide an advantage over other gabapentinoids. PEA belongs to a group of endogenous bioactive lipids called ALIAmides (autocoid local injury antagonist amides), which have a sense role in modulating numerous biological processes in particular non-neuronal neuroinflammatory responses to neuropathic injury and systemic inflammation. Multiple randomized trials and meta-analyses have demonstrated PEA's effectiveness in reducing pain severity arising from diverse pain phenotypes. Clonidine is an alpha2 adrenoceptor agonist and an imidazoline2 receptor agonist, which is U.S. Federal Drug Administration approved for attention deficit hyperactivity disorder in children, Tourette's syndrome, adjunctive therapy for cancer-related pain, and hypertension. Clonidine activation at alpha2 adrenoceptors causes downstream activation of inhibitory G-proteins (Gi/Go), which inhibits cyclic Adenosine monophosphate (AMP) production and hyperpolarizes neuron membranes, thus reducing allodynia. Intravenous clonidine has been used in terminally ill patients with poorly controlled symptoms, in particular pain and agitation.

Haloperidol (oral) versus olanzapine (oral) for people with schizophrenia and schizophrenia-spectrum disorders

BACKGROUND

Schizophrenia is often a severe and disabling psychiatric disorder. Antipsychotics remain the mainstay of psychotropic treatment for people with psychosis. In limited resource and humanitarian contexts, it is key to have several options for beneficial, low-cost antipsychotics, which require minimal monitoring. We wanted to compare oral haloperidol, as one of the most available antipsychotics in these settings, with a second-generation antipsychotic, olanzapine.

OBJECTIVES

To assess the clinical benefits and harms of haloperidol compared to olanzapine for people with schizophrenia and schizophrenia-spectrum disorders.

SEARCH METHODS

We searched the Cochrane Schizophrenia study-based register of trials, which is based on monthly searches of CENTRAL, CINAHL, ClinicalTrials.gov, Embase, ISRCTN, MEDLINE, PsycINFO, PubMed and WHO ICTRP. We screened the references of all included studies. We contacted relevant authors of trials for additional information where clarification was required or where data were incomplete. The register was last searched on 14 January 2023.

SELECTION CRITERIA

Randomised clinical trials comparing haloperidol with olanzapine for people with schizophrenia and schizophrenia-spectrum disorders. Our main outcomes of interest were clinically important change in global state, relapse, clinically important change in mental state, extrapyramidal side effects, weight increase, clinically important change in quality of life and leaving the study early due to adverse effects.

DATA COLLECTION AND ANALYSIS

We independently evaluated and extracted data. For dichotomous outcomes, we calculated risk ratios (RR) and their 95% confidence intervals (CI) and the number needed to treat for an additional beneficial or harmful outcome (NNTB or NNTH) with 95% CI. For continuous data, we estimated mean differences (MD) or standardised mean differences (SMD) with 95% CIs. For all included studies, we assessed risk of bias (RoB 1) and we used the GRADE approach to create a summary of findings table.

MAIN RESULTS

We included 68 studies randomising 9132 participants. We are very uncertain whether there is a difference between haloperidol and olanzapine in clinically important change in global state (RR 0.84, 95% CI 0.69 to 1.02; 6 studies, 3078 participants; very low-certainty evidence). We are very uncertain whether there is a difference between haloperidol and olanzapine in relapse (RR 1.42, 95% CI 1.00 to 2.02; 7 studies, 1499 participants; very low-certainty evidence). Haloperidol may reduce the incidence of clinically important change in overall mental state compared to olanzapine (RR 0.70, 95% CI 0.60 to 0.81; 13 studies, 1210 participants; low-certainty evidence). For every eight people treated with haloperidol instead of olanzapine, one fewer person would experience this improvement. The evidence suggests that haloperidol may result in a large increase in extrapyramidal side effects compared to olanzapine (RR 3.38, 95% CI 2.28 to 5.02; 14 studies, 3290 participants; low-certainty evidence). For every three people treated with haloperidol instead of olanzapine, one additional person would experience extrapyramidal side effects. For weight gain, the evidence suggests that there may be a large reduction in the risk with haloperidol compared to olanzapine (RR 0.47, 95% CI 0.35 to 0.61; 18 studies, 4302 participants; low-certainty evidence). For every 10 people treated with haloperidol instead of olanzapine, one fewer person would experience weight increase. A single study suggests that haloperidol may reduce the incidence of clinically important change in quality of life compared to olanzapine (RR 0.72, 95% CI 0.57 to 0.91; 828 participants; low-certainty evidence). For every nine people treated with haloperidol instead of olanzapine, one fewer person would experience clinically important improvement in quality of life. Haloperidol may result in an increase in the incidence of leaving the study early due to adverse effects compared to olanzapine (RR 1.99, 95% CI 1.60 to 2.47; 21 studies, 5047 participants; low-certainty evidence). For every 22 people treated with haloperidol instead of olanzapine, one fewer person would experience this outcome. Thirty otherwise relevant studies and several endpoints from 14 included studies could not be evaluated due to inconsistencies and poor transparency of several parameters. Furthermore, even within studies that were included, it was often not possible to use data for the same reasons. Risk of bias differed substantially for different outcomes and the certainty of the evidence ranged from very low to low. The most common risks of bias leading to downgrading of the evidence were blinding (performance bias) and selective reporting (reporting bias).

AUTHORS' CONCLUSIONS

Overall, the certainty of the evidence was low to very low for the main outcomes in this review, making it difficult to draw reliable conclusions. We are very uncertain whether there is a difference between haloperidol and olanzapine in terms of clinically important global state and relapse. Olanzapine may result in a slightly greater overall clinically important change in mental state and in a clinically important change in quality of life. Different side effect profiles were noted: haloperidol may result in a large increase in extrapyramidal side effects and olanzapine in a large increase in weight gain. The drug of choice needs to take into account side effect profiles and the preferences of the individual. These findings and the recent inclusion of olanzapine alongside haloperidol in the WHO Model List of Essential Medicines should increase the likelihood of it becoming more easily available in low- and middle- income countries, thereby improving choice and providing a greater ability to respond to side effects for people with lived experience of schizophrenia. There is a need for additional research using appropriate and equivalent dosages of these drugs. Some of this research needs to be done in low- and middle-income settings and should actively seek to account for factors relevant to these. Research on antipsychotics needs to be person-centred and prioritise factors that are of interest to people with lived experience of schizophrenia.

Clinical outcome and olanzapine plasma levels in acute schizophrenia

Purpose

This open label study was performed to evaluate the relationship between the plasma concentration of olanzapine and the response in acute schizophrenic inpatients.

Material and methods

A total of 54 inpatients, 38 males and 16 females, age ranging from 18 to 75 years, affected by Schizophrenia (DSM IV criteria) during an exacerbation phase were included in the study. Olanzapine (OLZ) was started at a dose of 5–20 mg/day and was increased to a mean dose of 15.27 mg ±5.53 S.D. Patients were evaluated at baseline, and after 2 weeks, by using BPRS, PANNS, HRS-D, EPSE, and ACS.

Results

BPRS and total PANSS showed a statistically significant improvement at the end of the study. Olanzapine plasma levels (PL) ranged from 5 to 120 ng/ml (mean 33.15 ng/ml ± 28.28 S.D.) and showed a positive correlation with OLZ dosage. A significant curvilinear correlation between OLZ PL and clinical improvement (BPRS, PANSS and HRS-D percent of amelioration) was observed.

Conclusion

Olanzapine plasma level determination seems to be a useful tool in optimizing acute treatment particularly for more problematic cases.

Dopamine Receptor Gene Expression Changes in Peripheral Blood Mononuclear Cells from Schizophrenic Patients Treated with Haloperidol and Olanzapine

We investigated dopamine receptor gene expression in peripheral blood mononuclear cells of schizophrenic patients before and after treatment. Also dopamine receptor genes expression profile was compared in two treatment groups including haloperidol and olanzapine. The peripheral blood mononuclear cells were separated from whole blood by Ficoll-hypaque; the total cellular RNA was extracted and the cDNA was synthesized. This process was followed by real-time polymerase chain reaction using primer pairs specific for five dopamine receptor mRNAs and β-actin as internal control. The results show the presence of all types of dopamine receptor in lymphocytes. Dopamine receptor gene expression profile in dopamine receptor D2 gene and dopamine receptor D4 gene showed significant changes that were correlated with the type of treatment and Clinical Global Impressions score improvement. In conclusion, the present study shows that human lymphocytes express dopamine receptor D1–D5 genes. Moreover, investigated dopamine receptors gene expression in peripheral blood mononuclear cells of schizophrenic patients correlated with clinical symptom improvement.

Intramuscular Haloperidol or Lorazepam and QT Intervals in Schizophrenia

The objective of this study was to estimate the effects of intramuscular haloperidol and lorazepam on the QT interval in volunteers with schizophrenia. Intramuscular haloperidol and intramuscular lorazepam are standard treatments in the acute management of agitation and aggression. Although prolongation of the QT interval and sequelae, including torsade de pointes and death, have been reported for haloperidol (but not lorazepam), formal studies have been lacking. Volunteers with schizophrenia (n = 12) were administered a single intramuscular injection of 7.5 mg haloperidol or 4 mg lorazepam in a blinded, randomized, placebo-controlled crossover design. Serial EKGs and concurrent blood samples were obtained over 6 hours following each injection. Changes in the QT interval were evaluated, as were plasma drug and prolactin concentrations. Haloperidol injection increased the heart rate-corrected QT interval an average of 5.1 msec using Bazett's correction (QTb 90% confidence interval [CI]: 0.3, 9.8), 3.6 msec using Fridericia's correction (QTf 90% CI: 0.02, 7.2), and 4.2 msec using an empirically derived "baseline correction" (QT(ii) 90% CI: 0.3, 8.0). Effects of lorazepam on QT were nullified by correction for the heart rate elevation (QTb 3.8 msec, 90% CI: 0.6, 7.1; QTf 0.0 msec, 90% CI: -3.2, 3.4; QTii -2.3 msec, 90% CI: -6.6, 2.0). An association between QT prolongation and occurrence of extrapyramidal symptoms was observed. On average, intramuscular haloperidol led to minimal prolongation of the QT interval. This propensity is of theoretical concern in individuals with risk factors for torsade de pointes but seems unlikely to be a problem in the vast majority of patients.

Antipsychotics, dopamine D₂ receptor occupancy and clinical improvement in schizophrenia: a meta-analysis

OBJECTIVE

Treatment of schizophrenia (SCZ) was revolutionized with the development of the antipsychotic medications. Although imaging studies have linked antipsychotic D₂ receptor occupancy and clinical response in SCZ, heterogeneity between cohorts and methods has made it challenging to generalize findings across studies. The main objective of this meta-analysis was to analyze the relationship between in vivo estimation of typical and atypical antipsychotic D₂ receptor occupancy and treatment response in SCZ.

METHODS

Using the keywords "dopamine D₂ receptor occupancy," "schizophrenia," "PET/SPECT" and "antipsychotics," and further refining our search to journal articles with information on % striatal D₂ occupancy and % change in clinical symptoms as indexed by either the BPRS or the PANSS, our final analysis consisted of 16 imaging studies (20 cohorts; N=206).

RESULTS

The first step of the meta-analysis confirmed the positive relationship between antipsychotic medication and clinical improvement in SCZ (ES=1.36; 95% CI: 1.13-1.60). The second step of our analysis revealed that when D₂ occupancy was limited to less than 80% in order to control for the appearance of extrapyramidal symptoms, high D₂ occupancy was correlated with reduction in clinical scores (r=0.4, p<0.001) for medications other than clozapine or quetiapine.

CONCLUSIONS

Our results suggest that D₂ occupancy is a contributing factor for the mechanism of antipsychotic effect in SCZ for some but not all antipsychotic medications.

Receptor targets for antidepressant therapy in bipolar disorder: an overview

The treatment of bipolar depression is one of the most challenging issues in contemporary psychiatry. Currently only quetiapine and the olanzapine-fluoxetine combination are officially approved by the FDA against this condition. The neurobiology of bipolar depression and the possible targets of bipolar antidepressant therapy remain relatively elusive. We performed a complete and systematic review to identify agents with definite positive or negative results concerning efficacy followed by a second systematic review to identify the pharmacodynamic properties of these agents. The comparison of properties suggests that the stronger predictors for antidepressant efficacy in bipolar depression were norepinephrine alpha-1, dopamine D1 and histamine antagonism, followed by 5-HT2A, muscarinic and dopamine D2 and D3 antagonism and eventually by norepinephrine reuptake inhibition and 5HT-1A agonism. Serotonin reuptake which constitutes the cornerstone in unipolar depression treatment does not seem to play a significant role for bipolar depression. Our exhaustive review is compatible with a complex model with multiple levels of interaction between the major neurotransmitter systems without a single target being either necessary or sufficient to elicit the antidepressant effect in bipolar depression.

Mechanisms of action of antipsychotic drugs of different classes, refractoriness to therapeutic effects of classical neuroleptics, and individual variation in sensitivity to their actions: Part I

Many issues remain unresolved about antipsychotic drugs. Their therapeutic potency scales with affinity for dopamine D2 receptors, but there are indications that they act indirectly, with dopamine D1 receptors (and others) as possible ultimate targets. Classical neuroleptic drugs disinhibit striatal cholinergic interneurones and increase acetyl choline release. Their effects may then depend on stimulation of muscarinic receptors on principle striatal neurones (M4 receptors, with reduction of cAMP formation, for therapeutic effects; M1 receptors for motor side effects). Many psychotic patients do not benefit from neuroleptic drugs, or develop resistance to them during prolonged treatment, but respond well to clozapine. For patients who do respond, there is a wide (>ten-fold) range in optimal doses. Refractoriness or low sensitivity to antipsychotic effects (and other pathologies) could then arise from low density of cholinergic interneurones. Clozapine probably owes its special actions to direct stimulation of M4 receptors, a mechanism available when indirect action is lost.

Not all partial dopamine D(2) receptor agonists are the same in treating schizophrenia. Exploring the effects of bifeprunox and aripiprazole using a computer model of a primate striatal dopaminergic synapse

Species differences in physiology and unique active human metabolites contribute to the limited predictive value of preclinical rodent models for many central nervous system (CNS) drugs. In order to explore possible drivers for this translational disconnect, we developed a computer model of a dopaminergic synapse that simulates the competition among three agents and their binding to pre- and postsynaptic receptors, based on the affinities for their targets and their actual concentrations. The model includes presynaptic autoreceptor effects on neurotransmitter release and modulation by presynaptic firing frequency and is calibrated with actual experimental data on free dopamine levels in the striatum of the rodent and the primate. Using this model, we simulated the postsynaptic dopamine D(2) receptor activation levels of bifeprunox and aripiprazole, two relatively similar dopamine D(2) receptor agonists. The results indicate a substantial difference in dose-response for the two compounds when applying primate calibration parameters as opposed to rodent calibration parameters. In addition, when introducing the major human and rodent metabolites of aripiprazole with their specific pharmacological activities, the model predicts that while bifeprunox would result in a higher postsynaptic D(2) receptor antagonism in the rodent, aripiprazole would result in a higher D(2) receptor antagonism in the primate model. Furthermore, only the highest dose of aripiprazole, but not bifeprunox, reaches postsynaptic functional D(2) receptor antagonism similar to 4 mg haloperidol in the primate model. The model further identifies a limited optimal window of functionality for dopamine D(2) receptor partial agonists. These results suggest that computer modeling of key CNS processes, using well-validated calibration paradigms, can increase the predictive value in the clinical setting of preclinical animal model outcomes.

Within-subject comparison of striatal D2 receptor occupancy measurements using [123I]IBZM SPECT and [11C]Raclopride PET

Antipsychotic-induced D2 receptor occupancy values tend to be lower when measured with [(123)I]IBZM SPECT than with [(11)C]Raclopride PET. To clarify this issue, D2 receptor occupancy was measured in the same subjects using both techniques. Twenty patients with schizophrenia on monotherapy with risperidone (n=7; 3-9 mg/d), olanzapine (n=5; 5-20 mg/d) or clozapine (n=8; 150-450 mg/d) at stable doses, and ten healthy volunteers (HV) underwent both a [(123)I]IBZM SPECT and a [(11)C]Raclopride PET examinations in random order on different days within a week. Patients with schizophrenia were scanned at a fixed interval after last dose administration. Quantification of receptor availability was performed using the most conventional methods from the literature: the tissue ratio derived specific uptake ratios (SUR) were used for SPECT, and simplified reference tissue model (SRTM) derived binding potentials (BP(ND)) for PET. Analysis was performed using both occipital cortex and cerebellum as reference regions for both modalities. Striatal D2 receptor occupancy was measured as the percentage reduction of [(123)I]IBZM SUR or [(11)C]Raclopride BP(ND) compared to the population average measured in HV using the same modality. Occupancy values measured by SPECT were lower than those measured with PET, by 12.4% and 13.8% when occipital cortex and cerebellum were used as reference regions. This difference should be taken in consideration when interpreting reported antipsychotic striatal D2 receptor occupancy values from the literature.

Pharmacokinetics and time-course of D(2) receptor occupancy induced by atypical antipsychotics in stabilized schizophrenic patients

The (123)I-IBZM SPECT measured D(2) receptor occupancy (D(2)RO) in chronically dosed, stabilized schizophrenic patients and its relationship with antipsychotic (AP) pharmacokinetics (PK) over time is still unclear. The aims of this study were: 1) To define the relationship between striatal D(2) receptor occupancy (D( 2)RO) and plasma concentration (C(P)) in stabilized schizophrenic patients on clinically relevant doses using (123)I-IBZM SPECT; 2) To investigate the time course of AP-induced D(2)RO and corresponding C(P). Forty-six schizophrenic patients on their clinically required doses of risperidone, olanzapine, clozapine or quetiapine were included. D( 2)RO and C(P) were measured over time following a sparse-sampling experimental design, and individual PK and D(2)RO-time profiles were estimated using a population approach. Observed striatal D(2)RO and C(P) ranges were 28-75% and 9.4-60.5 ng/mL for risperidone, 22-84% and 8.6-89.5 ng/mL for olanzapine, 5-53% and 41.6-818.2 ng/mL for clozapine and 0-64% and 37.9-719.6 ng/mL for quetiapine. A PK-D(2)RO relationship was found for the four APs. D(2)RO pattern over time was stable for risperidone, olanzapine and clozapine but fluctuating for quetiapine. Stabilized schizophrenic patients show a wide range of both D(2)RO and C(P) at clinically effective doses of the four AP, suggesting that clinical response to these AP may be maintained with D(2)RO below 65%. D(2)RO patterns over time differ between AP. These results should be considered for accurate interpretation of D(2)RO measurements, proper design of studies and optimization of drug regimens for patients on AP treatment.

Olanzapine therapy in anorexia nervosa: psychobiological effects

Dopamine impairments occur in anorexia nervosa. The aim of this study was to see whether treatment with the atypical dopamine antagonist antipsychotic olanzapine improves the disorder. Thirty anorexics, 18 restricted and 12 bingeing-purging, underwent a 3-month course of cognitive behavioral therapy, plus at random and double-blinded oral olanzapine (2.5 mg for 1 month, 5 mg for 2 months) in half and oral placebo in the other half of them. BMI, psychopathological aspects (eating disorder inventory, Hamilton Rating Scale, Buss-Durkee Rating Scale, Yale Brown Cornell for Eating Disorders Rating Scale, temperament-character inventory), and homovanillic acid blood concentrations for dopamine secretion, were monitored at baseline and then monthly during the trial. At the end of the trial BMI, total eating disorder inventory, total Yale Brown Cornell for Eating Disorders Rating Scale, Buss-Durkee Rating Scale, Hamilton Rating Scale scores and in olanzapine-treated patients the subitems of eating disorder inventory ineffectiveness and maturity fear, of Buss-Durkee Rating Scale direct aggressiveness, of temperament-characteristic inventory persistence had improved significantly. When stratified for anorexia nervosa subtype, BMI changes were significant among anorexia nervosa bingeing-purging patient, 'depression' (Hamilton Rating Scale) and 'direct aggressiveness' (Buss-Durkee Rating Scale) among anorexia nervosa bingeing-purging patients, 'persistence' (temprerament-characteristic inventory), among anorexics restricted patients, with a trend toward significance for obsessivity-compulsivity (Yale Brown Cornell for Eating Disorders Rating Scale). homovanilic acid blood levels increased significantly in the cognitive behavioral therapy+olanzapine group. No correlations were observed between homovanilic acid concentrations and psychopathological parameters. The pharmacological treatment can significantly improve specific aspects of anorexia nervosa.

Lower striatal dopamine transporter binding in neuroleptic-naive schizophrenic patients is not related to antipsychotic treatment but it suggests an illness trait

INTRODUCTION

Drug induced parkinsonism (DIP) is directly related to dopamine D2 receptor blockade. However, there are many references describing parkinsonian signs (PS) in naive-patients. In our previous study, we observed lower DAT binding in a group of first-episode schizophrenic patients after short-term treatment with risperidone, compared with age-matched healthy controls.

AIM

To clarify if DAT decrease could be an illness trait, excluding the effect of antipsychotics on DAT availability, and to determine whether DAT availability before treatment with antipsychotics may predict subsequent development of PS.

MATERIALS AND METHODS

A new series of 20 neuroleptic-naive schizophrenic patients and 15 healthy subjects was recruited. SPECT with [(123)I] FP-CIT (DaTSCAN(R)) was performed before starting antipsychotics and after 4 weeks of treatment. PS and psychopathological status were assessed by the Simpson-Angus (SAS), CGI and PANSS scales. Quantitative analyses of SPECTs were performed using ROIs placed in the caudate, putamen and occipital cortex.

RESULTS

Schizophrenic patients showed lower DAT binding compared with the healthy subjects at baseline (p<0.001) and after a 4-week-treatment period (p=0.001). Six out of eight schizophrenic patients of the DIP group were symptomatic for PS at baseline, in comparison to two out of 12 in the NoDIP group. Nonetheless, no differences were observed on DAT between DIP and NoDIP, neither at baseline (p=0.360) nor at endpoint (p=0.984). Finally, no differences between baseline-endpoint DAT binding were observed, neither in the DIP group (p=0.767) nor in the NoDIP group (p=0.093).

CONCLUSION

Our new series of first-episode naive-schizophrenic patients (1) points out DAT dysfunction as an illness trait due to the significantly lower DAT binding in schizophrenic patients in comparison to healthy subjects; (2) supports the results of other authors who describe PS in never-treated patients; (3) confirms that [(123)I] FP-CIT does not allow us to predict which patients will develop parkinsonism due to the lack of differences between DIP and NoDIP patients; and (4) confirms a null effect of antipsychotics on DAT due to the lack of differences in [(123)I] FP-CIT before and after a 4-week-treatment period.

Dopamine D2 receptor occupancy by risperidone: implications for the timing and magnitude of clinical response

The objective of the study is to investigate whether dopamine D2 receptor occupancy by risperidone and plasma levels over time can account for therapeutic efficacy and the latency period to response. Thirty-eight examinations with (123)I-IBZM single photon emission computed tomography were performed on 22 patients with schizophrenia, at diagnosis, 48 h after starting risperidone treatment and at a stable dose. Risperidone plasma levels were determined and psychopathologic evaluations (Brief Psychiatric Rating Scale, Positive and Negative Syndrome Scale) were carried out. No differences in the striatal/occipital (S/O) ratio or plasma levels were found between examinations at the 48-h time point and when a stable dose level had been established, so these parameters could not account for the latency period required for clinical response. D2 receptor occupancy at 48 h correlated positively with clinical improvement after 2 weeks of treatment. Therefore, if these results are confirmed, D2 receptor occupancy at the beginning of treatment with risperidone may be a predictor of subsequent clinical response.

Brain histamine H receptor occupancy of orally administered antihistamines measured by positron emission tomography with (11)C-doxepin in a placebo-controlled crossover study design in healthy subjects: a comparison of olopatadine and ketotifen

AIMS

The strength of sedation due to antihistamines can be evaluated by using positron emission tomography (PET). The purpose of the present study is to measure histamine H(1) receptor (H(1)R) occupancy due to olopatadine, a new second-generation antihistamine and to compare it with that of ketotifen.

METHODS

Eight healthy males (mean age 23.5 years-old) were studied following single oral administration of olopatadine 5 mg or ketotifen 1 mg using PET with (11)C-doxepin in a placebo-controlled crossover study design. Binding potential ratio and H(1)R occupancy were calculated and were compared between olopatadine and ketotifen in the medial prefrontal (MPFC), dorsolateral prefrontal (DLPFC), anterior cingulate (ACC), insular (IC), temporal (TC), parietal (PC), occipital cortices (OC). Plasma drug concentration was measured, and correlation of AUC to H(1)R occupancy was examined.

RESULTS

H(1)R occupancy after olopatadine treatment was significantly lower than that after ketotifen treatment in the all cortical regions (P < 0.001). Mean H(1)R occupancies for olopatadine and ketotifen were, respectively: MPFC, 16.7 vs. 77.7; DLPFC, 14.1 vs. 85.9; ACC, 14.7 vs. 76.1; IC, 12.8 vs. 69.7; TC, 12.5 vs. 66.5; PC, 13.9 vs. 65.8; and OC, 19.5 vs. 60.6. Overall cortical mean H(1)R occupancy of olopatadine and ketotifen were 15% and 72%, respectively. H(1)R occupancy of both drugs correlated well with their respective drug plasma concentrations (P < 0.001).

CONCLUSION

It is suggested that 5 mg oral olopatadine, with its low H(1)R occupancy and thus minimal sedation, could safely be used an antiallergic treatment for various allergic disorders. Abbreviations histamine H(1) receptor (H(1)R), histamine H(1) receptor occupancy (H(1)RO), dopamine D(2) receptor (D(2)R), positron emission tomography (PET), blood-brain barrier (BBB), binding potential ratio (BPR), distribution volume (DV).

Disminución del transportador de dopamina estriatal en primeros episodios psicóticos de pacientes esquizofrénicos tratados con risperidona

Extrapyramidal symptoms and Parkinsonism (PS) are side effects commonly observed with antipsychotic treatment. However, about 24% of never-treated schizophrenic patients may suffer from PS, which contrast with that 1% observed from the general population. 123I-FP-CIT SPECT has probe useful to differentiate degenerative from non-degenerative PS, so it could be interesting using it for establishing the functional state of presynaptic dopamine neurons of these patients.

AIM

To determine the dopamine transporter binding (DAT) in a homogeneous group of first-episode schizophrenic patients.

METHODS

An open, transversal study. Thirty schizophrenic in-patients and 15 healthy subjects were recruited. Patients were treated with similar doses of risperidone and all subjects were scanned with 123I-FP-CIT. Extrapyramidal symptoms and psychopathological status was assessed by Simpson-Angus, CGI and PANSS. Semi-quantitative analyses of SPECT images were performed using ROIs placed in caudate nucleus, anterior, medium and posterior putamen and occipital cortex.

RESULTS

Whole striatum 123I-FP-CIT binding ratio was significantly lower in patients than healthy subjects (t = 2.56, p < 0.014). This was observed in whole putamen (t = 2.66, p < 0.011), anterior (t = 2.35, p < 0.023), medium (t = 2.38, p < 0.022) and posterior putamen (t = 2.09, p < 0.042). No differences were observed in caudate nucleus (t = 1.81, p = 0.076). Females obtained higher binding ratios than males (t = -3.13, p < 0.003). No correlation was observed between 123I-FP-CIT binding ratios and clinical scales.

CONCLUSION

In our series, first episode schizophrenic patients treated with risperidone have a decrease striatal DAT binding assessed with 123I-FP-CIT SPECT. This alteration could be related to their own schizophrenia disease or be secondary to the antipsychotic treatment.

Olanzapine for schizophrenia

BACKGROUND

Olanzapine is an atypical antipsychotic reported to be effective without producing disabling extrapyramidal adverse effects associated with older, typical antipsychotic drugs.

OBJECTIVES

To determine the clinical effects and safety of olanzapine compared with placebo, typical and other atypical antipsychotic drugs for schizophrenia and schizophreniform psychoses.

SEARCH STRATEGY

We updated the first search [Biological Abstracts (1980-1999), The Cochrane Library (Issue 2, 1999), EMBASE (1980-1999), MEDLINE (1966-1999), PsycLIT (1974-1999) and The Cochrane Schizophrenia Group's Register (October 2000)] in October 2004 using the Cochrane Schizophrenia's Group's register of trials. We also searched references of all included studies for further trials, and contacted relevant pharmaceutical companies and authors.

SELECTION CRITERIA

We included all randomised clinical trials comparing olanzapine with placebo or any antipsychotic treatment for people with schizophrenia or schizophreniform psychoses.

DATA COLLECTION AND ANALYSIS

We independently extracted data and, for homogeneous dichotomous data, calculated the random effects relative risk (RR), the 95% confidence intervals (CI) and the number needed to treat (NNT) on an intention-to-treat basis. For continuous data we calculated weighted mean differences.

MAIN RESULTS

Fifty five trials are included (total n>10000 people with schizophrenia). Attrition from olanzapine versus placebo studies was >50% by six weeks, leaving interpretation of results problematic. Olanzapine appeared superior to placebo at six weeks for the outcome of 'no important clinical response' (any dose, 2 RCTs n=418, RR 0.88 CI 0.8 to 0.1, NNT 8 CI 5 to 27). Although dizziness and dry mouth were reported more frequently in the olanzapine-treated group, this did not reach statistical significance. The olanzapine group gained more weight. When compared with typical antipsychotic drugs, data from several small trials are incomplete. With high attrition in both groups (14 RCTs, n=3344, 38% attrition by six weeks, RR 0.81 CI 0.65 to 1.02) the assumptions included in all data are considerable. For the short term outcome of 'no important clinical response', olanzapine seems as effective as typical antipsychotics (4 RCTs, n=2778, RR 0.90 CI 0.76 to 1.06). People allocated olanzapine experienced fewer extrapyramidal adverse effects than those given typical antipsychotics. Weight change data for the short term are not statistically significant but results between three to 12 months suggest a clinically important average gain of four kilograms for people given olanzapine (4 RCTs, n=186, WMD 4.62, CI 0.6 to 8.64). Twenty three percent of people in trials of olanzapine and other atypical drugs left by eight weeks; 48% by three to12 months (11 RCTs, n=1847, RR 0.91 CI 0.82 to 1.00). There is little to choose between the atypicals, although olanzapine may cause fewer extrapyramidal adverse effects than other drugs in this category. Olanzapine produces more weight gain than other atypicals with some differences reaching conventional levels of statistical significance (1 RCT, n=980, RR gain at 2 years 1.73 CI 1.49 to 2.00, NNH 5 CI 4 to 7). There are very few data for people with first episode illness (1 RCT, duration 6 weeks, n=42). For people with treatment-resistant illness there were no clear differences between olanzapine and clozapine (4 RCTs, n=457).

AUTHORS' CONCLUSIONS

The large proportion of participants leaving studies early in these trials makes it difficult to draw firm conclusions on olanzapine's clinical effects. For people with schizophrenia it may offer antipsychotic efficacy with fewer extrapyramidal adverse effects than typical drugs, but more weight gain. There is a need for further large, long-term randomised trials with more comprehensive data.

An analysis of the effect of funding source in randomized clinical trials of second generation antipsychotics for the treatment of schizophrenia

OBJECTIVE

The effect of funding source on the outcome of randomized controlled trials has been investigated in several medical disciplines; however, psychiatry has been largely excluded from such analyses. In this article, randomized controlled trials of second generation antipsychotics in schizophrenia are reviewed and analyzed with respect to funding source (industry vs. non-industry funding).

METHOD

A literature search was conducted for randomized, double-blind trials in which at least one of the tested treatments was a second generation antipsychotic. In each study, design quality and study outcome were assessed quantitatively according to rating scales. Mean quality and outcome scores were compared in the industry-funded studies and non-industry-funded studies. An analysis of the primary author's affiliation with industry was similarly performed.

RESULTS

Results of industry-funded studies significantly favored second generation over first generation antipsychotics when compared to non-industry-funded studies. Non-industry-funded studies showed a trend toward higher quality than industry-funded studies; however, the difference between the two was not significant. Also, within the industry-funded studies, outcomes of trials involving first authors employed by industry sponsors demonstrated a trend toward second generation over first generation antipsychotics to a greater degree than did trials involving first authors employed outside the industry (p=0.05).

CONCLUSIONS

While the retrospective design of the study limits the strength of the findings, the data suggest that industry bias may occur in randomized controlled trials in schizophrenia. There appears to be several sources by which bias may enter clinical research, including trial design, control of data analysis and multiplicity/redundancy of trials.

Occupancy of dopamine D2 receptors by the atypical antipsychotic drugs risperidone and olanzapine: theoretical implications

RATIONALE

To examine the D2 occupancy of two commonly used antipsychotic medications and relate this to the D2 occupancy by endogenous dopamine in schizophrenia.

OBJECTIVES

The aim of this study is to compare the occupancy of striatal D2 receptors by the atypical antipsychotic medications risperidone and olanzapine at fixed dosages and to estimate the effect on D2 occupancy by dopamine as a result of these treatments.

METHODS

Seven patients with schizophrenia taking risperidone 6 mg/day and nine patients with schizophrenia taking olanzapine 10 mg/day underwent an [123I]IBZM SPECT scan after 3 weeks of treatment. The specific to non-specific equilibrium partition coefficient (V3") after bolus plus constant infusion of the tracer was calculated as [(striatal activity)/(cerebellar activity)]-1. D2 receptor occupancy was calculated by comparing V3" measured in treated patients to an age-corrected V3" value derived from a group of untreated patients with schizophrenia, previously published, according to the following formula: OCC=1-(V3" treated/V3" drug free).

RESULTS

V3" was significantly lower in risperidone treated patients compared with olanzapine treated patients (0.23+/-0.06 versus 0.34+/-0.08, P=-0.01), which translated to a significantly larger occupancy in schizophrenic patients treated with risperidone compared to olanzapine (69+/-8% versus 55 +/-11%, P=0.01). Data from our previous study were used to calculate the occupancy of striatal D2 receptors by antipsychotic medications required to reduce the occupancy of these receptors by endogenous dopamine to control values. In medication-free patients with schizophrenia, the occupancy of striatal D2 receptors by endogenous dopamine is estimated at 15.8%. In healthy controls, the occupancy of striatal D2 receptors by dopamine is estimated at 8.8%. In order to reduce the dopamine occupancy of striatal D2 receptors in patients with schizophrenia to control values, 48% receptor occupancy by antipsychotic medications is required.

CONCLUSIONS

These data indicate that the dosage of these medications, found to be effective in the treatment of schizophrenia, reduces DA stimulation of D2 receptors to levels slightly lower than those found in unmedicated healthy subjects.

Striatal dopamine D2 receptor density in neuroleptic-naive and in neuroleptic-free schizophrenic patients: an 123I-IBZM-SPECT study

Most post-mortem autoradiographic studies have described striatal dopamine D(2) receptor up-regulation due to chronic neuroleptic exposure. The aim of our study was to compare in-vivo striatal D(2) receptor density in neuroleptic-naive and neuroleptic-free schizophrenic patients. We included 28 young (mean age: 28+/-8 years) acute psychotic patients meeting DSM-IV criteria for schizophrenia or schizophreniform disorder. Enrolled patients were either first-episode neuroleptic-naive (n=12) or neuroleptic-free (n=16) after a minimum washout period of 7 days. All neuroleptic-free subjects had previously received neuroleptic treatment for a median period of 3.5 years. Both groups were evaluated using standard clinical scales. In-vivo striatal D(2) receptor binding was assessed by basal ganglia/frontal cortex ratios using (123)I-IBZM SPECT. No statistically significant differences were found in age or clinical assessment between neuroleptic-naive and neuroleptic-free schizophrenic patients. No differences were found in the basal ganglia/frontal cortex ratios of neuroleptic-naive (1.78+/-0.11) and neuroleptic-free (1.81+/-0.15) patients. No striatal uptake laterality was observed in either group. No correlation was demonstrated between BG/FC ratios and duration of illness, period of neuroleptic exposure or time of drug washout. We conclude that our neuroleptic-naive and neuroleptic-free schizophrenic patients did not show differences in striatal D(2) receptor binding, suggesting that IBZM-SPECT fails to detect D(2) receptor up-regulation induced by chronic exposure to neuroleptic drugs.

Positron emission tomography and single photon emission CT molecular imaging in schizophrenia

We reviewed findings from PET and SPECT studies that have contributed to our understanding of the pathophysiology and treatment of schizophrenia. The most robust set of findings pertains to imaging of presynaptic dopaminergic function in the striatum. The results of these studies have been consistent in showing that schizophrenia, at least during episodes of illness exacerbation, is associated with increased activity of DA neurons; this increased presynaptic activity is associated with positive symptoms and good therapeutic response. Studies of cortical DA function are less numerous and less consistent. In the future, technical advances in PET instrumentation and radioligand development should contribute to a clarification of the role of prefrontal DA in the cognitive impairment that is presented by these patients. An important drawback of the literature in this field is the generally low number of subjects that are included in studies (typically less than 20 per group). Small samples are necessitated by the cost of these investigations, but also, in some instances, to the difficulty in recruiting appropriate clinical subjects (such as drug-free patients who have schizophrenia). In conditions that are characterized by marked heterogeneity, such as major depressive disorders, this factor is bound to yield divergent results across studies. Another source of discrepancy is the variety of technical approaches to data acquisition and analysis. For example, analytical methods range from "empirical" or "semiquantitative" (typically a region of interest to a region of reference ratio measured at one time point) to model-based methods that use an arterial input function. The limitations that are associated with empirical analytical methods might account for artifactual results, especially when the effect size of the between-group difference and the number of subjects are small [149]. In addressing these limitations it will be important to increase the availability of these techniques beyond a few academic centers, to promote multi-center studies in well-characterized populations, and to standardize analytical methods. Until recently, SPECT was the only widely available technique, and SPECT studies have provided a substantial contribution to this field. With the current increase in PET camera availability, the development of [18F]-based molecular imaging probes will provide unique opportunities for further dissemination of these techniques. The article reviewed seminal findings obtained with PET and SPECT molecular imaging of schizophrenia. These techniques do not play a major role in the diagnosis and treatment of this disorder, remain essentially research tools. The results that have been produced by this field to date suggest that PET will significantly contribute to unraveling the biologic bases of psychiatric disorders and may contribute to their clinical management. Moreover, it is foreseeable that PET will become increasingly involved in the development of new psychiatric medications. Expanding the availability of PET and the current radiopharmaceutical portfolio will be critical for these predictions to become reality.

Striatal dopamine D2 receptor binding of risperidone in schizophrenic patients as assessed by 123I-iodobenzamide SPECT: a comparative study with olanzapine

The aim of this investigation was to compare the degree of striatal dopamine-(D2) receptor blockade by two atypical antipsychotic drugs, risperidone and olanzapine. The percentage of D2 receptor occupancy during treatment was calculated by comparing the results of 123I-iodobenzamide SPECT with those from healthy control subjects. Twenty inpatients suffering from schizophrenia or schizoaffective psychosis according to DSM IV/ICD-10 criteria were treated with clinically recommended doses of risperidone and compared with 13 inpatients treated with up to 20 mg olanzapine. Neuroleptic dose and D2 receptor blockade correlated strongly for both risperidone (Pearson r = -0.86, p = 0.0001) and olanzapine (Pearson r = -0.77, p = 0.002). There was no significant difference between the D2 receptor occupancy of the two substances when given in the clinically recommended dose range (unpaired t-test, t = -0.112, p = 0.911).