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Biomedical subjects

P Czobor

Publications and source records attributed to P Czobor.

At least 19 recordsLinked to original sources
PubMed2005

Selective anxiolysis produced by ocinaplon, a GABA(A) receptor modulator.

Benzodiazepines remain widely used for the treatment of anxiety disorders despite prominent, often limiting side effects including sedation, muscle relaxation, and ataxia. A compound producing a robust anxiolytic action comparable to benzodiazepines, but lacking these limiting side effects at therapeutic doses (an anxioselective agent), would represent an important advance in the treatment of generalized anxiety disorder, and perhaps other anxiety disorders. Here we report that the pyrazolo[1,5-a]-pyrimidine, ocinaplon, exhibits an anxioselective profile in both preclinical procedures and in patients with generalized anxiety disorder, the most common of the anxiety disorders. In rats, ocinaplon produces significant muscle relaxation, ataxia, and sedation only at doses >25-fold higher than the minimum effective dose (3.1 mg/kg) in the Vogel "conflict" test. This anticonflict effect is blocked by flumazenil (Ro 15-1788), indicating that like benzodiazepines, ocinaplon produces an anxiolytic action through allosteric modulation of GABA(A) receptors. Nonetheless, in eight recombinant GABA(A) receptor isoforms expressed in Xenopus oocytes, the potency and efficacy of ocinaplon to potentiate GABA responses varied with subunit composition not only in an absolute sense, but also relative to the prototypical benzodiazepine, diazepam. In a double blind, placebo controlled clinical trial, a 2-week regimen of ocinaplon (total daily dose of 180-240 mg) produced statistically significant reductions in the Hamilton rating scale for anxiety scores. In this study, the incidence of benzodiazepine-like side effects (e.g., sedation, dizziness) in ocinaplon-treated patients did not differ from placebo. These findings indicate that ocinaplon represents a unique approach both for the treatment and understanding of anxiety disorders.

Adult↗
PubMed2001

Differences in nicotine-induced dopamine release and nicotine pharmacokinetics between Lewis and Fischer 344 rats.

Studies have shown a greater preference for the self-administration of drugs such as nicotine and cocaine in the Lewis rat strain than in the Fischer 344 strain. We examined some factors that could contribute to such a difference. The baseline level of extracellular dopamine in nucleus accumbens shell was about 3-times higher in Fischer rats than in Lewis rats (3.18 +/- 0.26 vs. 1.09 +/- 0.14 pg/ sample). Nicotine (50-100 microg/kg)-induced release of dopamine, expressed in absolute terms, was similar in the two strains. Dopamine release expressed in relative terms (as percent of baseline), however, was significantly greater in Lewis rats than in Fischer rats at 30 min after the first nicotine injection. We suggest that the relative increase is of more influence than the absolute level for determining preference; a lower physiological extracellular dopamine level thus represent a risk factor for increased preference. Amphetamine-induced dopamine release expressed in relative terms was not greater in the Lewis strain. In the initial time period of the microdialysis experiments, a sharper peak in nicotine-induced accumbal dopamine release in Lewis and a less but more sustained release in Fischer rats was observed. This release pattern paralleled the faster clearance of nicotine from blood of Lewis compared to Fischer rats. In tissue slices the electrically induced dopamine release was highest in the nucleus accumbens and lowest in the ventral tegmentum. A significant effect of nicotine was lowering the electrically induced release of dopamine in frontal cortex slices from Fischer brain and increasing this dopamine release in the ventral tegmentum of Lewis brain slices indicating that the ventral tegmentum, an area controlling dopamine release in the accumbens, is more responsive to nicotine in the Lewis rat. Nicotine levels tended to be more sustained in Fischer rats in different brain regions, although the difference in nicotine levels between the strains was not significant at any time period. Several factors contribute to nicotine preference, including the endogenous dopamine level, and the sensitivity of ventral tegmentum neurons to nicotine-induced dopamine release. Strain differences in pharmacokinetics of nicotine may also play a role.

Animals↗
PubMed2001

Haloperidol blood levels in acute mania with psychosis.

In this study, the authors examined the relationship between steady-state haloperidol blood levels and clinical response in patients with acute psychotic mania. Fifty-four inpatients with acute mania were randomly assigned to receive either haloperidol 25 mg/day or haloperidol 5 mg/day. Each subject also received a concomitant medication: lorazepam 4 mg/day, lithium, or placebo. The relationship between steady-state haloperidol blood levels and clinical improvement was studied using analysis of covariance. There was wide interindividual variation in the haloperidol blood level-dose ratio. Haloperidol blood levels (log-transformed) were found to significantly correlate with clinical response in acute mania. Low-dose haloperidol with concomitant lithium may produce an optimal response in acute mania. Haloperidol blood levels may be clinically useful in identifying patients who are nonresponsive because of low drug levels and, hence, in enhancing optimal haloperidol dosing for acute mania with psychosis.

Adult↗
PubMed2001

Olanzapine for schizophrenia refractory to typical and atypical antipsychotics: an open-label, prospective trial.

The role of olanzapine in treatment-resistant schizophrenia is still unresolved. This article presents an open-label, prospective, 14-week trial with olanzapine in patients with schizophrenia and schizoaffective disorder selected for unambiguous resistance to either clozapine or risperidone and to typical antipsychotics. Forty-three inpatients (mean age, 41.6 years; mean duration of illness, 21.7 years) were enrolled and treated after cross-titration from their previous antipsychotic treatment with olanzapine 10 to 40 mg daily without any concomitant antipsychotic medication. Patients were evaluated with the Positive and Negative Syndrome Scale (PANSS), the Clinical Global Impressions Scale, and the Extrapyramidal Symptom Rating Scale. The change with olanzapine treatment was associated with a PANSS total score improvement of 3.7 (SD = 15.6; not significant). There was a significant improvement for the PANSS cognitive and depression/anxiety factors, whereas the PANSS excitement factor worsened. The improvement rate was superior in patients receiving olanzapine doses higher than 20 mg. A total of 16.7% of patients reached response criteria set forth by a previous study. There was a significant decrease in extrapyramidal side effects (t = 2.04; p < 0.05) and statistically significant, yet modest, weight gain. These results indicate that olanzapine is only modestly effective in these severely treatment-resistant patients with schizophrenia. However, a trial with olanzapine can be recommended in these patients before moving to augmentation strategies, given the lack of proven alternatives and the observation that 16.7% of patients reached the response criteria.

Adult↗
PubMed2001

Effects of clozapine, olanzapine, risperidone, and haloperidol on hostility among patients with schizophrenia.

OBJECTIVE: This study compared the specific antiaggressive effects of clozapine with those of olanzapine, risperidone, and haloperidol. METHODS: A total of 157 inpatients with schizophrenia or schizoaffective disorder and a history of suboptimal treatment response were randomly assigned to receive clozapine, olanzapine, risperidone, or haloperidol in a double-blind 14-week trial. The trial was divided into two periods: eight weeks during which the dosage was escalated and then fixed, and six weeks during which variable dosages were used. The hostility item of the Positive and Negative Syndrome Scale (PANSS) was the principal outcome measure. Covariates included the items that reflect positive symptoms of schizophrenia (delusions, suspiciousness or feelings of persecution, grandiosity, unusual thought content, conceptual disorganization, and hallucinations) and the sedation item of the Nurses Observation Scale for Inpatient Evaluation (NOSIE). RESULTS: Patients differed in their treatment response as measured by the hostility item of the PANSS. The scores of patients taking clozapine indicated significantly greater improvement than those of patients taking haloperidol or risperidone. The effect on hostility appeared to be independent of the antipsychotic effect of clozapine on other PANSS items that reflect delusional thinking, a formal thought disorder, or hallucinations and independent of sedation as measured by the NOSIE. Neither risperidone nor olanzapine showed superiority to haloperidol. CONCLUSION: Clozapine has a relative advantage over other antipsychotics as a specific antihostility agent.

Adult↗
PubMed2000

Pretreatment plasma HVA and haloperidol response in acute mania.

INTRODUCTION: Pretreatment plasma homovanillic acid (HVA) levels have been reported to be a correlate of clinical response to typical antipsychotics for schizophrenic, bipolar manic, and mixed groups of psychotic patients. Biological markers of clinical response to antipsychotics could be useful for optimizing drug treatment. METHOD: Thirty-one consenting acute inpatient subjects between ages 19 and 66 years with a DSM-III-R clinical diagnosis of bipolar disorder, manic with psychotic features were entered into this double-blind study and were randomly assigned to receive either haloperidol 25 mg/day or haloperidol 5 mg for the 3-week study. Subjects also received one of the following concomitant medications: standard lithium, lorazepam 4 mg/day, or placebo. RESULTS: The primary multiple regression analysis, including all subjects on both haloperidol doses, yielded a significant main effect for pretreatment plasma HVA (n=31, F=5.7, P=0.025), indicating that higher pretreatment plasma HVA was predictive of better clinical response. In addition, the interaction between haloperidol dose and pretreatment plasma HVA was also significantly associated with clinical response (F=12.59, P=0.0015). When the two haloperidol doses were analyzed separately, we found that pretreatment plasma HVA was only correlated with clinical response in the low haloperidol 5 mg/day group (n=18, F=11.73, P=0.0038) and was unrelated to clinical response to the high haloperidol 25 mg/day group. LIMITATIONS: The sample size was small. Results may have been confounded by prior antipsychotic treatment and concomitant use of lithium or lorazepam. DISCUSSION: These results suggest that pretreatment plasma HVA could be useful for dosing antipsychotics. Patients with high plasma HVA levels would be good candidates for low-dose treatment because they are more likely to improve on such a dose, while patients with low plasma HVA levels might warrant more rapid dosage escalation.

Acute Disease↗
PubMed2000

Subject selection for the placebo- and comparator-controlled trials of neuroleptics in schizophrenia.

It has been suggested that inclusion of a placebo treatment arm in controlled clinical trials might bias the selection of study subjects. Presumably, patients in the placebo-controlled studies are more stable, but there are no data available to support such an assumption. The authors tested the hypothesis in a set of randomized trials of neuroleptics in treating schizophrenia by comparing placebo-controlled (PCTs) and comparator-controlled trials (CCTs) in terms of basic patient characteristics. The results, based on a total of 296 studies, showed that the patients in PCTs, compared with those in CCTs, were older (p < 0.002), had a longer duration of illness (p < 0.001), and a lower initial symptom severity (p < 0.02). No difference was found in the number of subjects per treatment arm or in the proportion of female subjects. However, investigation of studies which used same-gender study subjects revealed that female-only populations were more likely to be tested in PCTs (p < 0.03) than in CCTs. To investigate current trends in psychopharmacologic research, the authors tested separately a subset of trials of new atypical antipsychotics. The results indicated a significantly smaller number of females participating in the latest PCTs (p < 0.0003). Moreover, our findings suggest that the characteristics of patients in the current controlled trials are rather uniform; thus, the generalizability of new study findings for certain groups of patients with schizophrenia (e.g., with early or late onset or brief duration of illness) may be compromised.

Antipsychotic Agents↗
PubMed2000

High-dose treatment with haloperidol: the effect of dose reduction.

High doses of antipsychotic medications are sometimes prescribed in clinical practice, although the efficacy and safety of such treatment have not been established. The purpose of this study was to determine whether high-dose, long-term antipsychotic treatment prescribed on the basis of clinical judgment can be justified. Patients who were receiving high doses of haloperidol were screened, and those patients whose plasma levels were at least 15 ng/mL were randomly assigned to an experimental group (N = 11) or to a control group (N = 12). The experimental group underwent a dose reduction to achieve the target plasma level of 10 ng/mL. The reduction was gradual over a period of 12 weeks. The control group treatment was maintained at the original level. Both groups were then followed up for another 16 weeks, during which the plasma levels of haloperidol were kept constant. The study used double-blind procedures. Both groups showed an average slight symptom reduction. There was no significant difference in the severity of symptoms between the two groups at any time point. The dose reduction had no apparent adverse effects. Thus, the results of this study did not provide justification for high-dose, long-term antipsychotic treatment. However, these results must be interpreted with caution because the sample studied here was small and biased.

Adult↗
PubMed2000

Suicidal behavior in patients with schizophrenia is related to COMT polymorphism.

A common functional polymorphism that results in a three- to four-fold difference in catechol-O-methyltransferase (COMT) enzyme activity has been related to psychiatric disorders such as ultra-ultra rapid cycling bipolar disorder, drug abuse and alcoholism (Lachman et al., 1996a; Karayiorgou et al., 1997; Vandenbergh et al., 1997; Papolos et al., 1998; Tiihonen et al., 1999). Several studies have also reported associations between the allele encoding the low enzyme activity COMT variant (L allele) and other-directed aggression (Strous et al., 1997; Lachman et al., 1998; Kotler et al., 1999) in schizophrenic and schizoaffective patients. The current study investigated whether the COMT L allele is also associated with suicide attempts in schizophrenic and schizoaffective patients. COMT genotypes were determined and history of suicide attempts was retrospectively investigated in a Finnish sample (n = 94) and a US sample (n = 54). Significant associations were observed between COMT genotype and suicide; specifically, history of violent suicide attempts. The COMT L allele was more frequent in subjects who had attempted suicide by violent means. These associations were significant in males but not females. These findings support a common neurobiological substrate for self- and other-directed aggression, and suggest that catecholaminergic alterations may contribute to these behaviors in schizophrenic and schizoaffective patients.

Adult↗
PubMed1999

Effects of haloperidol treatment on prolactin response to D-fenfluramine challenge in acute schizophrenia.

We have previously described an association between higher serotonin (5-HT) responsivity, indexed by prolactin response to D-fenfluramine challenge, and poorer treatment response to haloperidol in non-medicated schizophrenics. The aim of the present study was to investigate the effects of antidopaminergic treatment on the prolactin response in the repeated challenge test. D-Fenfluramine was administered to 22 young, acutely ill schizophrenics (11 females and 11 males) after 4 weeks of haloperidol treatment. Whereas neuroleptic administration significantly raised basal prolactin levels (P < 0.0001), subsequent D-fenfluramine challenge produced an additional significant increase (P < 0.001). Moreover, the magnitude of this increase was not different from the pretreatment response. Our results demonstrate that prolactin response to the challenge is mediated through the 5-HT system. An observed negative association between posttreatment prolactin response and therapeutic response to haloperidol did not reach statistical significance.

Acute Disease↗
PubMed1999

Symptomatic overlap of cocaine intoxication and acute schizophrenia at emergency presentation.

Cocaine intoxication and acute abstinence alter brain dopaminergic functioning, resulting in behavioral changes closely mimicking the positive and negative symptoms of schizophrenia. In emergency room settings, recent cocaine abuse can be mistaken for schizophrenia and may cause inappropriate diagnosis and in some instances medical mismanagement. Schizophrenia patients presenting with recent cocaine abuse may also present with significant diagnostic and treatment dilemmas. This study attempts to distinguish between cocaine and schizophrenic psychosis by examining patients who present with both recent cocaine abuse and acute schizophrenia (CA+SZ), cocaine intoxication without schizophrenic illness (CA), and acute schizophrenia with no comorbid substance abuse (SZ) within the first 24 hours after arrival at the Bellevue psychiatric emergency service. Clinical assessment included the Brief Psychiatric Rating Scale, the Schedule for the Assessment of Positive Symptoms, and the Schedule for the Assessment of Negative Symptoms. Both cocaine abusing groups were required to have positive urine toxicology screens for inclusion in the study. Multivariate analysis of variance showed the CA+SZ patients present with a clinical profile that overlaps with CA patients on mood and negative symptom dimensions and overlaps with SZ patients on most positive symptoms. CA+SZ patients differed from both groups, however, by presenting with significantly more hallucinatory experiences than cocaine abusing or schizophrenia patient counterparts. Despite considerable overlap, each group of patients presented with a discernible cross-sectional symptom pattern.

Acute Disease↗
PubMed1999

Course of violence in patients with schizophrenia: relationship to clinical symptoms.

To understand the heterogeneity of violent behaviors in patients with schizophrenia, one must consider underlying clinical symptoms of the illness and their change over time. The purpose of this study was to examine persistence and resolution of violence in relation to psychotic symptoms, ward behaviors, and neurological impairment. Psychiatric symptoms and ward behaviors were assessed in violent inpatients with schizophrenia or schizoaffective disorder and in nonviolent controls on entry into the study. Patients were followed for 4 weeks; those who showed resolution of assaults over this time were classified as transiently violent, and those who remained assaultive were categorized as persistently violent. At the end of the 4 weeks, psychiatric symptoms, ward behaviors, and neurological impairment were assessed. Overall, the two violent groups presented with more severe psychiatric symptoms and were judged to be more irritable than the nonviolent control subjects, but the transiently violent patients showed improvement in symptoms over time. At the end of 4 weeks, the persistently violent patients had evidence of more severe neurological impairment, hostility, suspiciousness, and irritability than the other two groups. Canonical discriminant analyses identified two significant dimensions differentiated the groups. The first, characterized by positive psychotic symptoms, differentiated the violent patients from the control subjects; the second, characterized by neurological impairment and high endpoint score for negative symptoms, differentiated the transiently from the persistently violent patients. Identification of certain symptoms associated with different forms of violence has important implications for the prediction and differential treatment of violent behavior in patients with schizophrenia.

Adult↗
PubMed1999

Acute mania: haloperidol dose and augmentation with lithium or lorazepam.

Antipsychotic dosing for acute mania has not been well studied. Combined treatment with lithium and an antipsychotic is the most common treatment, but additional antimanic efficacy of a lithium-antipsychotic combination beyond that of an antipsychotic alone has not been well demonstrated. Furthermore, the possibility that lithium could affect antipsychotic dose requirement is believed to have never been studied. In this study, 63 acutely psychotic bipolar manic inpatients were randomly assigned to receive double-blind treatment with 1 of 2 haloperidol doses, 25 mg/day or 5 mg/day, for 21 days. In addition to haloperidol, subjects were randomly assigned to receive concomitant treatment with placebo, standard lithium, or lorazepam 4 mg/day. The high haloperidol dose produced greater improvement and more side effects than did the low dose. Lithium added to the low dose produced a markedly greater clinical response than did the low dose alone. Lorazepam did not improve the outcome for the patients receiving low-dose haloperidol. The clinical response produced by high-dose haloperidol was not enhanced by adding either lithium or lorazepam. All treatment effects emerged by the fourth day of treatment and persisted. Used alone, a haloperidol dose of 5 mg/day is too low for most manic patients, but concomitant lithium produces a dose-dependent enhancement of haloperidol response. Lorazepam 4 mg/day was insufficient to produce an advantage when added to low-dose haloperidol.

Adult↗
PubMed1999

Psychopathy and violent behavior among patients with schizophrenia or schizoaffective disorder.

OBJECTIVE: Although a strong association between violence and psychopathy has been demonstrated in nonpsychotic forensic populations, the relationship between psychopathy and violence among patients with schizophrenia has not been thoroughly explored. Patients with and without a history of persistent violent behavior were compared for comorbidity of psychopathy and schizophrenia or schizoaffective disorder. METHODS: Violent and nonviolent patients were identified through reviews of hospital charts and records of arrests and convictions. The Psychopathy Checklist: Screening Version was administered to 51 patients, 26 violent patients and 25 matched nonviolent patients. Analysis of variance was used as the principal statistical method for comparing violent and nonviolent groups. RESULTS: Mean psychopathy scores were higher for violent patients than nonviolent patients. Five of the violent patients (19 percent) had scores exceeding the cutoff for psychopathy, and 13 (50 percent) scored in the possible psychopathic range. All of the nonviolent patients scored below the cutoff for possible psychopathy. Higher psychopathy scores were associated with earlier age of onset of illness and more arrests for both violent and nonviolent offenses. CONCLUSIONS: The comorbidity of schizophrenia and psychopathy was found to be higher among violent patients than among nonviolent patients. Violent patients with schizophrenia who score high on measures of psychopathy may have a personality disorder that precedes the emergence of psychotic symptoms, or they may constitute a previously unclassified subtype of schizophrenia, characterized by early symptoms of conduct disorder symptoms and persistent violent behavior.

Antisocial Personality Disorder↗
PubMed1998

Change in plasma prolactin and clinical response to haloperidol in schizophrenia and schizoaffective disorder.

There has been a long-standing interest in plasma prolactin as a potential in vivo indicator of blockade of tuberoinfundibular D2 dopamine receptors. Potential relationships between prolactin response and neuroleptic treatment have been obscured by the use of high doses which have caused prolactin to plateau. With lower doses of neuroleptic now commonly in use, prolactin may be more valuable as a correlate of clinical response. In this study, 23 acutely exacerbated schizophrenic and schizoaffective patients were washed out for at least 6 days and were then treated with haloperidol to achieve fixed low to moderate plasma levels under double-blind conditions. Clinical response, plasma prolactin, and haloperidol plasma levels were measured weekly for 3 weeks. Clinical symptoms at endpoint were related to both prolactin change and final prolactin level during haloperidol treatment. Specifically, fewer symptoms at endpoint were associated with a greater increase in prolactin over time and a higher prolactin level at endpoint. Thus, prolactin increase caused by low to moderate doses of haloperidol may be a correlate of endpoint symptomatology. As lower doses of typical neuroleptics are now in use, prolactin response as a predictor of clinical response may have more clinical utility. Further study of prolactin and clinical response to typical neuroleptics should focus on low neuroleptic doses.

Adult↗
PubMed1998

Prolactin response to D-fenfluramine challenge test as a predictor of treatment response to haloperidol in acute schizophrenia.

D-fenfluramine has been identified as a highly selective serotonin (5-HT) releaser and re-uptake inhibitor. The objective of our study was to investigate prolactin response to D-fenfluramine challenge in non-medicated, first episode schizophrenics. We hypothesized that 5-HT reactivity can predict a response to the neuroleptic treatment. Twenty-three inpatients, 11 males and 12 females, at the Prague Psychiatric Center participated in the study. Inclusion criteria were: ICD-10 diagnosis of schizophrenia, first episode or duration of illness shorter than 36 months. D-fenfluramine challenge test was performed before 4 weeks of the haloperidol treatment. During the test, prolactin plasma levels were measured. The Brief Psychiatric Rating Scale (BPRS) was administered before and after the treatment. A statistically significant negative correlation was found between prolactin response to the D-fenfluramine challenge and improvement of psychopathology measured by the change in total BPRS score (p = 0.0004), in positive (p = 0.0403), negative (p = 0.0267), and anxiety-depression symptoms of BPRS (p = 0.0014). Our data support the original hypothesis that there is a relationship between 5-HT system activity and treatment response. The higher responsiveness of the 5-HT system in first episode, non-medicated schizophrenics, was associated with a poorer treatment response to haloperidol, an antidopaminergic neuroleptic.

Adult↗