Problems in evaluating new antipsychotic drugs

A number of novel antipsychotics were registered and introduced into clinical practice in the last decade. These include olanzapine, quetiapine, risperidone, sertindole and zotepine as well as ziprasidone, which is still in the registration process. It quickly became apparent, that it is not always easy to translate results from phase II and III clinical trials into everyday clinical practice. In this context, we discuss methodological aspects that mainly deal with selection of patients for clinical trials and clinical trial methodology. Next to that, an overview of the current knowledge concerning novel antipsychotics is given. There is no doubt that these drugs broaden the therapeutic spectrum made available to patients suffering from schizophrenia. On the other hand, it is evident that there is still a need for a critical evaluation of the risk-benefit-ratio of novel antipsychotics. Clinical psychiatrists also face the challenge to modify some of the traditional treatment approaches. These prerequisites will allow the embedding of novel antipsychotics into modern integrative treatment concepts of schizophrenia.     

Plasma concentrations of antipsychotic drugs in psychiatric inpatients

We surveyed a random sample (n = 75) of doctors and dentists at University College Hospital, Ibadan, Nigeria. They were offered anonymous testing for hepatitis B surface antigen (HBsAg), hepatitis Be antigen (HBeAG), antibodies to hepatitis B core antigen (anti-HBc) and to hepatitis C virus (anti-HCV), by enzyme immunoassay. The results suggest a high prevalence of hepatitis B virus (HBV) with a high potential of transmissibility, as well as a high prevalence of HCV infection. The majority of the doctors and dentists use universal precaution for protection against viral hepatitis on < 50% of the occasions when they carry out procedures on their patients. Infection with HBV was associated with type of specialty (surgeons, dentists) and lack of HBV vaccination (p < 0.05). After logistic regression, these factors were independently associated with HBV infection (p < 0.05). Sixty (80%) had not received prior HBV vaccination. Unvaccinated personnel were more likely to be surgeons, dentists, < 37 years of age, and have fewer years of professional activity (p < 0.05). After logistic regression, only fewer years of professional activity remained independently associated with lack of vaccination (p < 0.05). To reduce the occupational exposure of HBV, universal precautions must be rigorously adhered to when the doctors and dentists carry out procedures on their patients, and all health-care workers should be vaccinated with HBV vaccine and the HCV vaccine, when it becomes available.     

Inhibition of neuronal nitric oxide synthase by antipsychotic drugs

Hydralazine was administered at cardiac catheterization to eight children with a ventricular septal defect (age: 2.2-8.8 years), and the extent of afterload reduction was determined using aortic input impedance and wall stress. The pulmonary to systemic blood flow ratio decreased from 2.2 +/- 0.8 to 1.8 +/- 0.4 (p < 0.05) and the pulmonary systemic resistance ratio increased from 0.11 +/- 0.08 to 0.13 +/- 0.10 (p < 0.05) after hydralazine administration. Hydralazine reduced mean aortic pressure and the amplitude of the late systolic peak of the aortic pressure wave. Peak flow velocity in the descending aorta increased from 62 +/- 14 to 81 +/- 24 cm/sec (p < 0.05). Peripheral resistance decreased significantly from 13.3 +/- 5.9 to 6.6 +/- 3.7 10(3) dyn sec/cm3 (p < 0.05). The modulus of the first harmonic, indicating pulse wave reflection, decreased from 1196 +/- 575 to 815 +/- 382 dyn sec/cm3 (p < 0.05). The characteristic impedance, indicating aortic stiffness, did not change. End-systolic wall stress decreased significantly from 54.4 +/- 16.7 to 34.8 +/- 10.2 g/cm2 (p < 0.01). Hydralazine acutely achieved afterload reduction by reducing both peripheral resistance and pulse wave reflection, and increased stroke volume.     

Management of acute extrapyramidal effects induced by antipsychotic drugs

The management of acute extrapyramidal effects (EPEs) induced by antipsychotic drugs is reviewed. EPEs associated with antipsychotics include acute dystonias, pseudoparkinsonism, and akathisia. Acute dystonias consist of abnormal muscle spasms and postures and usually occur three to five days after antipsychotic therapy begins or the dosage is increased. Acute dystonias should be treated with anticholinergic medications or benzodiazepines. Antipsychotic-induced pseudoparkinsonism has the same clinical appearance as idiopathic parkinsonism. Symptoms generally appear within the first three months. Pseudoparkinsonism is managed by lowering the anti-psychotic dosage or by adding an anticholinergic agent or a mantadine; switching to a low-potency agent or an atypical antipsychotic may also help. Akathisia is characterized by subjective feelings of restlessness and anxiety and objective signs of motor activity, such as inability to sit still. This EPE appears days to weeks after antipsychotic exposure begins and can be difficult to manage. If reduction of the antipsychotic dosage or a switch to a less potent antipsychotic is not practical or effective, an anticholinergic, beta-blocker, or benzodiazepine may be added. Lipophilic beta-blockers, especially propranolol and metoprolol, appear to be the most effective treatments. Anticholinergic agents are commonly given to prevent acute dystonias, especially in high-risk patients, but long-term prophylaxis is controversial. Atypical antipsychotics may have less potential to induce EPEs. Options in the management of antipsychotic-associated EPEs include using the lowest effective dosage of antipsychotic, treating the reactions with medications, and changing the antipsychotic to one with less potential for inducing EPEs.     

Atypical antipsychotic drugs selectively increase neurotensin efflux in dopamine terminal regions

Typical antipsychotic drugs, such as haloperidol and chlorpromazine, increase synthesis of the neuropeptide neurotensin (NT) in both the striatum and the nucleus accumbens, whereas atypical antipsychotic drugs, such as clozapine and olanzapine, do so only in the nucleus accumbens. By using in vivo microdialysis, we now report that acute administration of haloperidol, clozapine, or olanzapine failed to alter the release of NT in either the striatum or nucleus accumbens. In contrast, chronic administration of haloperidol for 21 days increased NT release in both the striatum and nucleus accumbens, whereas treatment for 21 days with the atypical antipsychotic drugs, clozapine or olanzapine, increased NT release selectively in the nucleus accumbens. These findings suggest that (i) increased NT mRNA expression and NT tissue concentrations are associated with increases in the extracellular fluid concentrations of the peptide and (ii) atypical antipsychotic drugs may exert their therapeutic effects and produce fewer side effects by virtue of their selectivity in limbic compared with striatal, target neurons.     

Emergency treatment of psychotic symptoms. Pharmacokinetic considerations for antipsychotic drugs

Psychotic symptoms related to mental and medical disorders can pose a medical emergency. Selecting an appropriate antipsychotic medication to treat this emergency is based on the clinical situation, preferred route of administration, pharmacokinetic profile of the antipsychotic and the medications currently being taken by the patient. Intramuscular preparations are usually preferred over oral medication when the patients are not co-operative and require drugs with a faster onset of action and good bioavailability. High potency antipsychotics such as haloperidol and fluphenazine are effective in stabilising patients with psychotic symptoms quickly. Loxapine is an alternative when sedation is necessary and molindone is useful if a short-acting antipsychotic is required. Rapid neuroleptisation with intramuscular preparations of antipsychotic achieves therapeutic drug concentrations more rapidly, and also provides optimal control of psychotic symptoms. If the patient is cooperative, liquid oral preparations can be used; they are as effective as intramuscular formulations. If long term treatment with an antipsychotic in necessary and patients are stabilised, they can be switched from intramuscular to oral preparations. The oral dose is usually 1.5 to 5 times the total intramuscular dose per day, based on the bioavailability of the antipsychotic medication. If the patient is currently taking antipsychotic medication when the emergency situation occurs, it is usually adequate to increase the dose of antipsychotic drug. Appropriate dose adjustment or antipsychotic selection is necessary when drug interactions are expected. An in-depth knowledge of the pharmacokinetic profile and drug interaction profile of antipsychotic in necessary for the selection of the appropriate antipsychotic for any given emergency situation.     

Use of antipsychotic drugs in a long-term care institution. Experiences with implementing clinical guidelines]

Anti-psychotic drugs (neuroleptics) are useful for treating psychoses. However, non-psychotic patients, particularly patients with a deviant behaviour pattern, are often also treated with anti-psychotic drugs. The drugs may induce serious side-effects and should only be used on strict indications and at the lowest possible dosage. In a nursing home for deaf people with additional handicaps we introduced clinical guidelines for the use of anti-psychotic drugs and recorded their use during a two-year period. We found there was a reduction in the number of patients taking anti-psychotic drugs (from 32/54 to 26/54, p = 0.03), as well as a decrease in dosage per user (from median 2.4 mg to 1.7 mg equivalents of haloperidol, p = 0.05). Both the number of patients who were given depot injections and the number of different anti-psychotic drugs per patient were reduced. We conclude that it is possible to reduce the use of anti-psychotic drugs in institutions where long-term care is provided for disabled people.     

Risperidone compared with new and reference antipsychotic drugs: in vitro and in vivo receptor binding

Risperidone and its active metabolite 9-OH-risperidone were compared to reference antipsychotic drugs (haloperidol, pipamperone, fluspirilene, clozapine, zotepine) and compounds under development (olanzapine, seroquel, sertindole, ORG-5222, ziprasidone) for in vitro binding to neurotransmitter receptors in brain tissue and on membranes of recombinant cells expressing cloned human receptors and for in vivo occupancy of neurotransmitter receptors in rat and guinea-pig brain following acute treatment (2 h., s.c.). An ex vivo autoradiography technique was applied to determine the receptor occupancy by the drugs administered in vivo. Of particular interest are the central 5HT2A receptors and D2-type receptors. Predominant 5HT2A receptor antagonism is supposed to add to an atypical profile of the antipsychotics (treatment of the negative symptoms, low incidence of extrapyramidal side effects). D2 antagonism is required the treatment of positive symptoms. A contribution of the new dopamine receptor subtypes D3 and in particular D4 receptors has been proposed. In vitro, all compounds, except the 'typical' antipsychotics haloperidol and fluspirilene, showed higher affinity for 5HT2A than for D2 receptors. Subnanomolar affinity for human 5HT2A receptors was observed for ORG-5222, sertindole, risperidone, 9-OH-risperidone and ziprasidone. Fluspirilene, ORG-5222, haloperidol, ziprasidone, risperidone, 9-OH-risperidone and zotepine displayed nanomolar affinity for human D2 receptors. Sertindole and olanzapine were slightly less potent. Pipamperone, clozapine and seroquel showed 2 orders of magnitude lower D2 affinity in vitro. Clozapine, but even more so pipamperone, displayed higher affinity for D4 than for D2 receptors. For most other compounds, D4 affinity was only slightly lower than their D2 affinity. Seroquel was totally devoid of D4 affinity. None of the compounds had nanomolar affinity for D1 receptors; their affinity for D3 receptors was usually slightly lower than for D2 receptors. In vivo, ORG-5222, risperidone, pipamperone, 9-OH-risperidone, sertindole, olanzapine, zotepine and clozapine maintained a higher potency for occupying 5HT2A than D2 receptors. Risperidone and ORG-5222 had 5HT2A versus D2 potency ratio of about 20. Highest potency for 5HT2A receptor occupancy was observed for ORG-5222 followed by risperidone and olanzapine. Ziprasidone exclusively occupied 5HT2A receptors. ORG-5222, haloperidol, fluspirilene and olanzapine showed the highest potency for occupying D2 receptors. No regional selectivity for D2 receptor occupancy in mesolimbic versus nigrostriatal areas was detected for any of the test compounds. Risperidone was conspicuous because of its more gradual occupancy of D2 receptors; none of the other compounds showed this property. The various compounds also displayed high to moderate occupancy of adrenergic alpha 1 receptors, except fluspirilene and ziprasidone. Clozapine, zotepine, ORG-5222 and sertindole occupied even more alpha 1 than D2 receptors. Clozapine showed predominant occupancy of H1 receptors and occupied cholinergic receptors with equivalent potency to D2 receptors. A stronger predominance of 5HT2A versus D2 receptor occupancy combined with a more gradual occupancy of D2 receptors differentiates risperidone and its 9-OH-metabolite from the other antipsychotic compounds in this study. The predominant 5HT2A receptor occupancy probably plays a role in the beneficial action of risperidone on the negative symptoms of schizophrenia, whereas maintenance of a moderate occupancy of D2 receptors seems adequate for treating the positive symptoms of schizophrenia. A combined 5HT2A and D2 occupancy and the avoidance of D2 receptor overblockade are believed to reduce the risk for extrapyra     

Maintenance antipsychotic drugs do prevent relapse: A reply to Tobias and MacDonald.

Responds to L. L. Tobias and M. L. MacDonald's (see record 1994-03715-001) questioning of the assumption that long-term administration of antipsychotic drugs prevents relapse in chronic psychotics. Tobias and MacDonald asserted that the conclusions of studies maintaining this assumption were not warranted because of methodological flaws in the research. The present authors argue that some of these criticisms are incorrect, while others are valid. The effects of these methodological sources of error, however, would have operated in the direction of increasing variability and thus decreasing the chances of finding a significant difference between the drug and placebo group. In fact there are 25 controlled studies, essentially all of which find that any antipsychotic drug prevents relapse. A total of 377 out of 1,884 patients on drugs relapsed (20%) in comparison to 705 out of 1,346 patients on placebo (52%). It is concluded that Tobias and MacDonald's evidence for the value of maintenance medicine was misstated and misleading. The present authors emphasize this conclusion in light of the widespread use of maintenance medicine with chronic schizophrenics. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

抗精神分裂症药物诱发迟发性运动障碍与COMT基因多态性的关联性分析

目的:通过分析中国北方汉族人群中精神分裂症患者COMT基因多态性Val158Met 分布,研究COMT基因多态性与精神分裂症及迟发性运动障碍(TD)发生的关系.方法:采集356例并发TD的精神分裂症患者( TD组)、419例不发生TD的精神分裂症患者(非TD组)及471例正常健康人 (正常对照组)的全血样本,提取基因组DNA,应用TaqMan探针检测COMT基因多态性Val158Met基因型和等位基因的分布.结果:正常对照组与精神分裂症组比较,基因型与等位基因频数分布差异均无统计学意义(χ2=3.08,df=3,P=0.21;χ2=2.067,df=2,P=0.15).TD组与正常对照组比较,基因型与等位基因频数分布差异均无统计学意义(χ2=1.857,df=3,P=0.40;χ2 =1.281,df=2,P=0.26).非TD组与正常对照组比较,基因型与等位基因频数分布差异均无统计学意义(χ2=2.505,df=3,P=0.29;χ2=1.709,df=2,P=0.19).TD组与非TD组比较,基因型与等位基因频数分布差异均无统计学意义(χ2=0.021,df=3,P=0.99;χ2=0.013,df=2,P=0.91).结论:精神分裂症的发生与COMT基因多态性Val158Met无关联性,精神分裂症患者并发TD与COMT基因多态性Val158Met无关联性.     

Effect of novel antipsychotic drugs on phencyclidine-induced stereotyped behaviour and social isolation in the rat social interaction test

Phencyclidine (PCP) induces stereotyped behaviour and social isolation in rats; comparisons with clinical observations have suggested that these behaviours may mimic certain aspects of the positive and the negative symptoms, respectively, of an acute schizophrenic episode. Novel antipsychotics are effective in treating the positive symptoms in schizophrenic patients and have also shown some promise in treating the negative symptoms. In the present study the effects of the novel antipsychotics remoxipride (2.5-20 mg/kg), risperidone (0.02-0.63 mg/kg), sertindole (0.01-2.5 mg/kg), olanzapine (0.16-2.5 mg/kg) and quetiapine (0.16-10 mg/kg) on PCP-induced behaviours were determined. The drugs were administered daily for 3 or 21 days in combination with vehicle or 2.0 mg/kg of PCP for the last 3 days of the administration regime, and the rats were tested using the social interaction test. The antipsychotic drugs all reliably reduced the level of PCP-induced stereotyped behaviour and had distinct effects on PCP-induced social isolation. Comparison with clinical findings suggests that the PCP-induced behaviours respond to treatment with antipsychotic drugs in a manner that correlates well with clinical observations, and that this animal model of schizophrenia may be useful for evaluating novel drug candidates. However, the study also showed that additional experiments are required to determine the specificity by which antipsychotic drugs alleviate PCP-induced behaviours because most of the drugs also affected considerably the behaviour of the control animals.     

Placebo cigarettes in smoking research.

This review outlines the development and use of placebo cigarettes in smoking research. Research on effects of smoking has been disadvantaged by the lack of an adequate placebo condition. Recently, tobacco-based denicotinized cigarettes have been used in smoking research to distinguish effects of smoking due to the delivery of nicotine, other components of tobacco smoke, and the sensory process of smoking. Placebo cigarettes do not increase heart rate and blood pressure or produce electroencephalogram changes ordinarily associated with nicotine. However, placebo cigarettes reduce subjective measures of tobacco craving, desire to smoke, and tobacco withdrawal. These findings indicate that the effects of cigarette smoking are dependent on the delivery of nicotine, tar, other compounds of tobacco smoke, and the sensory stimuli. The next generation of research may begin to investigate the mechanisms that modulate these placebo effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chemotherapeutic trials with four drugs in crossbred calves experimentally infected with Theileria annulata

Between October 1987 and July 1990, of 763 patients undergoing open heart surgery, 43 (5.6%) were 80 (mean and median 82) years of age or older. There were 20 men and 23 women. Eighteen patients (42%) were initially assessed using the angina score of the New York Heart Association or Canadian Cardiovascular Association as class IV. Nine procedures (21%) were performed electively and 34 (79%) urgently. A total of 26 patients (60%) underwent coronary bypass surgery, while 11 (26%) had valve replacements and six (14%) had both coronary bypass surgery and valve replacement; 74% of the patients received two or more grafts. The hospital mortality rate of the octogenarian patients was 9% (four of 43), significantly higher (P < 0.05) than the overall hospital mortality rate of 3.6% for patients < or = 79 years of age. A history of myocardial infarction within 2 weeks before the procedure was obtained in nine of 43 patients (21%); 22 (51%) had experienced at least one myocardial infarction before surgery. Ejection fractions were 'normal' in 28 patients (65%), 'fair' in nine (21%) and 'poor' in six (14%). The mean length of hospital stay for the octogenarian patients was 19 (range 8-64) days. Thirty-five of the 39 operative survivors were followed for a mean of 14 (range 3-35) months. The actuarial probability of survival was 86% at the end of this time. A total of 31 patients (79%) assessed using the angina score of the New York Heart Association or Canadian Cardiovascular Association were class I or II. During the follow-up period.(ABSTRACT TRUNCATED AT 250 WORDS)     

Placebo Psychotherapies and Nonconscious Learning in the Placebo Effect: Reply to Kirsch (2004).

In this reply, the authors explore several issues raised by I. Kirsch (2004; see record 2004-11156-008) concerning their original article (S. Stewart-Williams & J. Podd, 2004; see record 2004-11156-007), which dealt with the roles of expectancy and classical conditioning in the placebo effect. The only notable disagreement concerns a definitional issue, namely, Stewart-Williams and Podd's claim that the placebo concept can be extended to inert psychotherapies. The authors defend this claim against the criticisms Kirsch raised. In addition, they comment on the suggestion that nonconscious learning processes play only a small role in human placebo effects, arguing that there are theoretical reasons to expect these processes to be more important than has previously been recognized. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of unique profile antipsychotic drugs on extracellular amino acids in the ventral pallidum and globus pallidus of rats

The effects of antipsychotic drugs (APDs) on brain dopamine receptors in the striatum are ultimately expressed through efferent projections which primarily use amino acid transmitters, including gamma-aminobutyric acid and glutamate. The present study examined the effects of APDs on extracellular amino acid levels in the rat ventral pallidum (VP) and globus pallidus (GP), areas that receive projections from distinct striatal subregions. Clozapine, an APD with low motor side effect liability, and metoclopramide, a low-potency APD with high motor side effect liability, were compared with haloperidol, a widely used APD with high motor side effect liability. Drugs were administered subcutaneously and amino acid levels were monitored concurrently in the VP and GP by intracranial microdialysis. High doses of haloperidol and metoclopramide increased and clozapine decreased extracellular gamma-aminobutyric acid levels in the GP but not the VP. Low, but not high, doses of the three drugs tended to increase extracellular glutamate levels in both pallidal regions. Clozapine, but not the other two drugs, decreased extracellular threonine in the GP and glycine and threonine in the VP. Results indicate a correlation between increased gamma-aminobutyric acid levels in the GP and the propensity of the APDs tested to induce motor side effects. The novel effects of clozapine on extracellular glycine and threonine further distinguish this drug as a unique antipsychotic compound.