Discovery of a Small Molecule Activator of Slack (Kcnt1) Potassium Channels That Significantly Reduces Scratching in Mouse Models of Histamine-Independent and Chronic Itch

Various disorders are accompanied by histamine-independent itching, which is often resistant to the currently available therapies. Here, it is reported that the pharmacological activation of Slack (Kcnt1, KNa1.1), a potassium channel highly expressed in itch-sensitive sensory neurons, has therapeutic potential for the treatment of itching. Based on the Slack-activating antipsychotic drug, loxapine, a series of new derivatives with improved pharmacodynamic and pharmacokinetic profiles is designed that enables to validate Slack as a pharmacological target in vivo. One of these new Slack activators, compound 6, exhibits negligible dopamine D2 and D3 receptor binding, unlike loxapine. Notably, compound 6 displays potent on-target antipruritic activity in multiple mouse models of acute histamine-independent and chronic itch without motor side effects. These properties make compound 6 a lead molecule for the development of new antipruritic therapies targeting Slack.

Improving the pharmacotherapeutic treatment of agitation associated with bipolar disorder

INTRODUCTION

Agitation is commonly encountered in people with bipolar disorder, particularly when experiencing a manic episode. The number of approved pharmacological agents to manage acute episodes of agitation in this population is limited.

AREAS COVERED

A search was conducted using the US National Library of Medicine PubMed.gov resource for English-language papers of clinical trials and reviews/meta-analyses, using the text words 'bipolar disorder' AND 'agitation,' as well as any papers with both two text words in the title, without any date restrictions.

EXPERT OPINION

Existing pharmacologic options approved by regulatory authorities for the treatment of acute episodes of agitation associated with bipolar disorder have similar degrees of efficacy but differ in their tolerability profiles and ease of use, giving clinicians an opportunity to individualize treatment. The goal is to treat mild-moderate agitation before it evolves into severe agitation, encouraging noninvasive pharmacologic treatment options. Inhaled loxapine and sublingual dexmedetomidine are newer options with rapid onset of action and may be preferable for patients willing to cooperate with treatment.

Haematologic malignancies associated with clozapine v. all other antipsychotic agents: a pharmacovigilance study in VigiBase®

BACKGROUND

Clozapine is mainly used in patients with treatment-resistant schizophrenia and may lead to potentially severe haematologic adverse events, such as agranulocytosis. Whether clozapine might be associated with haematologic malignancies is unknown. We aimed to assess the association between haematologic malignancies and clozapine using Vigibase®, the WHO pharmacovigilance database.

METHODS

We performed a disproportionality analysis to compute reporting odds-ratio adjusted for age, sex and concurrent reporting of antineoplastic/immunomodulating agents (aROR) for clozapine and structurally related drugs (loxapine, olanzapine and quetiapine) compared with other antipsychotic drugs. Cases were malignant lymphoma and leukaemia reports. Non-cases were all other reports including at least one antipsychotic report.

RESULTS

Of the 140 226 clozapine-associated reports, 493 were malignant lymphoma cases, and 275 were leukaemia cases. Clozapine was significantly associated with malignant lymphoma (aROR 9.14, 95% CI 7.75-10.77) and leukaemia (aROR 3.54, 95% CI 2.97-4.22). Patients suffering from those haematologic malignancies were significantly younger in the clozapine treatment group than patients treated with other medicines (p < 0.001). The median time to onset (available for 212 cases) was 5.1 years (IQR 2.2-9.9) for malignant lymphoma and 2.5 years (IQR 0.6-7.4) for leukaemia. The aROR by quartile of dose of clozapine in patients with haematologic malignancies suggested a dose-dependent association.

CONCLUSIONS

Clozapine was significantly associated with a pharmacovigilance signal of haematologic malignancies. The risk-benefit balance of clozapine should be carefully assessed in patients with risk factors of haematologic malignancies. Clozapine should be used at the lowest effective posology.

The Management of Psychomotor Agitation Associated with Schizophrenia or Bipolar Disorder: A Brief Review

The early and correct assessment of psychomotor agitation (PMA) is essential to ensure prompt intervention by healthcare professionals to improve the patient’s condition, protect healthcare staff, and facilitate future management. Proper training for recognizing and managing agitation in all care settings is desirable to improve patient outcomes. The best approach is one that is ethical, non-invasive, and respectful of the patient’s dignity. When deemed necessary, pharmacological interventions must be administered rapidly and avoid producing an excessive state of sedation, except in cases of severe and imminent danger to the patient or others. The purpose of this brief review is to raise awareness about best practices for the management of PMA in emergency care situations and consider the role of new pharmacological interventions in patients with agitation associated with bipolar disorder or schizophrenia.

[New medical approach to out-of-hospital treatment of psychomotor agitation in psychiatric patients: a report of 14 cases]

This case series explored the usefulness of an inhaled dose of 9.1 mg of loxapine administered outside the hospital to treat psychomotor agitation related to schizophrenia, bipolar disorder, or schizoaffective disorder. The Clinical Global Impression Scale and the Positive and Negative Syndrome Scale (excitement component) were used to assess the effects of treatment in 14 patients. The treatment was useful in 12 patients, who showed significant improvement (P<.001) after inhalation. We conclude that inhaled loxapine is useful for treating out-of-hospital psychomotor agitation related to a psychiatric disorder. Mechanical restraint and parenteral medication can be avoided after use of this drug. Loxapine treatment shortens the agitation episode and attenuates the impact on the patient, facilitating ambulance transfer.

Inhaled loxapine for the urgent treatment of acute agitation associated with schizophrenia or bipolar disorder

BACKGROUND

Acute agitation is a serious complication of schizophrenia and bipolar disorder, which may escalate quickly to aggressive behavior. Rapid treatment is therefore important to calm and stabilize the patient, reducing the potential for harm to the patient and others, and allowing further assessment. Current guidelines suggest that where pharmacologic intervention is indicated, medication should preferably be non-invasive, should have a rapid onset and should control aggressive behavior in the short term without compromising the physician-patient relationship in the long term.

OBJECTIVES

This article presents an overview of a new inhaled formulation of the established antipsychotic loxapine, which aims to provide a more rapidly acting agent for the treatment of acute agitation without the disadvantages of intramuscular or intravenous injection.

DISCUSSION

Inhaled loxapine is rapidly absorbed with intravenous-like pharmacokinetics, with a time to maximum plasma concentration of 2 minutes and a plasma half-life of approximately 6 hours. In phase III studies, loxapine reduced agitation within 10 minutes of inhalation; agitation was decreased at all subsequent assessments during a 24-hour evaluation period. Inhaled loxapine was generally well tolerated with no undue sedation. The most common adverse events were dysgeusia, mild sedation, and dizziness. Inhaled loxapine is contraindicated in patients with asthma, COPD or other pulmonary disease associated with bronchospasm.

CONCLUSIONS

Inhaled loxapine rapidly reduces acute agitation in patients with schizophrenia or bipolar disorder and is generally well tolerated. The non-invasive route of delivery respects the patient's autonomy, reducing the perception of coercion or forced medication. Inhaled loxapine is therefore an effective and appropriate option for use in the emergency setting in patients with acute agitation.

Haloperidol versus first-generation antipsychotics for the treatment of schizophrenia and other psychotic disorders

BACKGROUND

Haloperidol is worldwide one of the most frequently used antipsychotic drugs with a very high market share. Previous narrative, unsystematic reviews found no differences in terms of efficacy between the various first-generation ("conventional", "typical") antipsychotic agents. This established the unproven psychopharmacological assumption of a comparable efficacy between the first-generation antipsychotic compounds codified in textbooks and treatment guidelines. Because this assumption contrasts with the clinical impression, a high-quality systematic review appeared highly necessary.

OBJECTIVES

To compare the efficacy, acceptability, and tolerability of haloperidol with other first-generation antipsychotics in schizophrenia and schizophrenia-like psychosis.

SEARCH METHODS

In October 2011 and July 2012, we searched the Cochrane Schizophrenia Group's Trials Register, which is based on regular searches of CINAHL, BIOSIS, AMED, EMBASE, PubMed, MEDLINE, PsycINFO, and registries of clinical trials. To identify further relevant publications, we screened the references of all included studies and contacted the manufacturers of haloperidol for further relevant trials and missing information on identified studies. Furthermore, we contacted the corresponding authors of all included trials for missing data.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) that compared oral haloperidol with another oral first-generation antipsychotic drug (with the exception of the low-potency antipsychotics chlorpromazine, chlorprothixene, levopromazine, mesoridazine, perazine, prochlorpromazine, and thioridazine) in schizophrenia and schizophrenia-like psychosis. Clinically important response to treatment was defined as the primary outcome. Secondary outcomes were global state, mental state, behaviour, overall acceptability (measured by the number of participants leaving the study early due to any reason), overall efficacy (attrition due to inefficacy of treatment), overall tolerability (attrition due to adverse events), and specific adverse effects.

DATA COLLECTION AND ANALYSIS

At least two review authors independently extracted data from the included trials. The methodological quality of the included studies was assessed using The Cochrane Collaboration`s 'Risk of bias' tool.We analysed dichotomous outcomes with risk ratios (RR) and continuous outcomes with mean differences (MD), both with the associated 95% confidence intervals (CI). All analyses were based on a random-effects model and we preferably used data on an intention-to-treat basis where possible.

MAIN RESULTS

The systematic review currently includes 63 randomised trials with 3675 participants. Bromperidol (n = 9), loxapine (n = 7), and trifluoperazine (n = 6) were the most frequently administered antipsychotics comparator to haloperidol. The included studies were published between 1962 and 1993, were characterised by small sample sizes (mean: 58 participants, range from 18 to 206) and the predefined outcomes were often incompletely reported. All results for the main outcomes were based on very low or low quality data. In many trials the mechanism of randomisation, allocation, and blinding was frequently not reported. In short-term studies (up to 12 weeks), there was no clear evidence of a difference between haloperidol and the pooled group of the other first-generation antipsychotic agents in terms of the primary outcome "clinically important response to treatment" (40 RCTs, n = 2132, RR 0.93 CI 0.87 to 1.00). In the medium-term trials, haloperidol may be less effective than the other first-generation antipsychotic group but this evidence is based on only one trial (1 RCT, n = 80, RR 0.51 CI 0.37 to 0.69).Based on limited evidence, haloperidol alleviated more positive symptoms of schizophrenia than the other antipsychotic drugs. There were no statistically significant between-group differences in global state, other mental state outcomes, behaviour, leaving the study early due to any reason, due to inefficacy, as well as due to adverse effects. The only statistically significant difference in specific side effects was that haloperidol produced less akathisia in the medium term.

AUTHORS' CONCLUSIONS

The findings of the meta-analytic calculations support the statements of previous narrative, unsystematic reviews suggesting comparable efficacy of first-generation antipsychotics. In efficacy-related outcomes, there was no clear evidence of a difference between the prototypal drug haloperidol and other, mainly high-potency first-generation antipsychotics. Additionally, we demonstrated that haloperidol is characterised by a similar risk profile compared to the other first-generation antipsychotic compounds. The only statistically significant difference in specific side effects was that haloperidol produced less akathisia in the medium term. The results were limited by the low methodological quality in many of the included original studies. Data for the main results were low or very low quality. Therefore, future clinical trials with high methodological quality are required.

Loxapine for schizophrenia

BACKGROUND

Some authors have suggested that loxapine is more effective than typical antipsychotics in reducing the negative symptoms of schizophrenia, that extrapyramidal adverse effects are not usually seen at clinically effective antipsychotic doses and that it should therefore be classed as atypical.

OBJECTIVES

To determine the effects of loxapine compared with placebo, typical and other atypical antipsychotic drugs for schizophrenia and related psychoses.

SEARCH STRATEGY

For this 2007 update, we searched the Cochrane Schizophrenia Group's Register (January 2007).

SELECTION CRITERIA

We included all randomised controlled clinical trials relevant to the care of schizophrenia that compared loxapine to other treatments.

DATA COLLECTION AND ANALYSIS

We independently inspected abstracts ordered papers, re-inspected and quality assessed these. For dichotomous data we calculated relative risks (RR) and their 95% confidence intervals (CI) on an intention-to-treat basis based on a fixed effects model. We calculated numbers needed to treat/harm (NNT/NNH) where appropriate. For continuous data, we calculated weighted mean differences (WMD) again based on a fixed effects model.

MAIN RESULTS

We were able to include 41 studies in this review. Compared with placebo, loxapine has an antipsychotic effect (Global effect - not improved at six weeks: n=78, 2 RCTs, RR 0.30 CI 0.1 to 0.6 NNT 3 CI 3 to 5). It is as effective as typical drugs in the short term (4 -12 weeks) (Global effect: n=580, 13 RCTs, RR 0.86 CI 0.7 to 1.1; mental state: n=915, 6 RCTs, RR 0.89 CI 0.8 to 1.1). Very limited heterogeneous data suggest that, given intramuscularly (IM), loxapine may be at least as sedating as IM haloperidol and thiothixene. Loxapine is also as effective as atypicals (risperidone, quetiapine) (n=468, 6 RCTs, RR mental state not improved 1.07 CI 0.8 to 1.5). Adverse effect profile is similar to typicals but loxapine may cause more extrapyramidal adverse effects when compared with atypicals (n=340, 4 RCTs, RR 2.18 CI 1.6 to 3.1).

AUTHORS' CONCLUSIONS

Loxapine is an antipsychotic which is not clearly distinct from typical or atypical drugs in terms of its effects on global or mental state. Loxapines profile of adverse effects is similar to that of the older generation of antipsychotic drugs.

Approche thérapeutique d’une population de patients présentant des troubles psychotiques aigus ou chroniques : enquête RÉALITÉ (Recherche Épidémiologique sur l’Activité de la Loxapine et ses Indications en Thérapeutique quotidiennE)

A retrospective observational pharmaco-epidemiological survey was conducted during 24 weeks between October 2004 and March 2005 in metropolitan France (384 investigators) to more clearly define the use of loxapine in acute and chronic psychotic states. The objective of this national survey was to specify the clinical and therapeutic profile of patients managed by this antipsychotic in two cohorts of adult patients: one in "acute phase" (prescription of loxapine during the previous 4 weeks), the other in "maintenance phase" (prescription of loxapine for more than 8 weeks). The two groups of the recruited population (1,511 patients) presented identical sociodemographic data. Selection criteria were adapted to the data collected to ensure statistically relevant analysis: 696 patients in acute phase and 633 patients in maintenance phase. The acute phase group was predominantly composed of known patients (82% of patients had a psychotic history) with schizophrenia (47%) or mood disorders (57%) who had already presented acute episodes (an average of 5.4). The current episode consisted of a state of agitation (88%) lasting an average of two weeks, requiring hospitalization (87%), scheduled admission [HDT (admission at the request of another person) in 47.5% of cases and HO (statutory admission) in 40.8% of cases] and prescription of loxapine monotherapy (56%) at a mean daily dose of 177,3 mg. The maintenance phase group comprised a population of known patients (87.5%), schizophrenics (63%), presenting psychotic symptoms (dissociation 82%, delusions 74%) or mood disorders (71%) requiring voluntary hospitalization (78%) for a mean duration of 180 days and a prescription of loxapine monotherapy in 28% of cases at a mean daily dose of 131.6 mg. The loxapine-haloperidol combination (21%) was prescribed more frequently in the second group in the case of chronic disorders; in the other cases, loxapine was coprescribed with the main second generation antipsychotics: risperidone (16%), olanzapine (16%), amisulpride (11%). CGI assessment of the overall study population revealed a marked or very marked clinical improvement with no significant adverse effects in more than 80% of cases.

[Survey of management methods for patients in a state of agitation at admission and emergency departments in France]

The increasing prevalence of the agitation states in the emergency department (ED) is a problem little studied on the epidemiological plan.

OBJECTIVE

To define the prevalence of the agitation states in the ED in France, to determine predicative criteria of the agitation states to prevent a potentially dangerous situation and take care as fast as possible of it, to know current practices in front of these situations, and to collect the recommendations of the departmental managers of the ED to improve this management.

METHOD

A questionnaire of appraisal was sent to the 464 managers of the ED of hospitals and clinics in metropolitan France, containing 21 questions.

RESULTS

137 (29.5%) departmental managers answered. The average of admittances by ED is 24,000 a year. The estimated prevalence of the number of situations of agitation represents 1.22% of the total of admittances. The average prevalence a month and by service of verbal attacks is 36.3, that of the physical attacks is 1.14. The number of attacks (and their consequences) correlate with admittances by ED. The intervention of the police is required on average 17 times a year and by ED. Only 29.5% of the ED consider to have premises adapted for the management of the agitated patients; 32.3% of the ED have a protocol established for the agitation states; 16.3% of services accumulate a protocol and a training of the professionals; 10.5% of establishments have at the same moment adapted premises, a protocol and a forming of the staff for the management of the agitated patients. Among the agitated patients, those that profit by a sedation represent on average 67.7% and it varies according to ED. The sedative treatment used in first intention is loxapine in intramuscular injection for 84% of them. The predicative factors identified of agitation states are intoxications, mainly the alcohol (88%) and the poly drug addiction (46.3%). More than half of the ED recommend in a systematic way and for lack of diagnostic orientation the dosages of alcohol, drugs, glycaemia and bloody electrolytes; 85% of the departmental managers consider that a better management of the agitation states rests on the presence of adapted premises and on a specific forming of the nursing staff.

CONCLUSION

The management of the agitated patients in the ED requires the placing of protocols and of specific trainings as well as of adapted premises. The major prevalence of attacks imposes realization of epidemiological studies and the priority placing of a coherent politics, considering the potential and often real gravity of these behavioural problems.

Human genetic variations in the 5HT2A receptor: a single nucleotide polymorphism identified with altered response to clozapine

OBJECTIVE

to determine if the agonist serotonin and antagonists loxapine and clozapine have an altered potency for four allelic variants (T25N, I197V, A447V, and H452Y) of the human 5HT2A receptor when compared to the wild-type allele.

METHODS

The receptor or its variants are studied in an in-vitro functional assay system consisting of a Sf9 insect cell line that is stably transformed with the human wild-type and mutant alleles. This assay system measures release of calcium stores due to receptor activation by agonists and inhibition of this agonist stimulated response by antagonists.

RESULTS

Both loxapine and clozapine exhibit non-competitive antagonism of serotonin stimulation of the human 5HT2A receptor signal transduction system and loxapine is the more potent inhibitor. This study shows that the I197V allele requires a two-fold higher concentration of the atypical neuroleptic clozapine to inhibit serotonin stimulation compared to the wild-type receptor (P = 0.036). The I197V mutation does not affect the inhibition of serotonin stimulation by the typical neuroleptic loxapine nor does it alter the activation of the receptor by serotonin. It is also significant that the results of this study indicate that the T25N, A447V, and H452Y mutations in the human 5HT2A receptor do not significantly alter the response of the receptor to the agonist serotonin or the antagonists loxapine and clozapine.

Effect of loxapine on peripheral dopamine-like and serotonin receptors in patients with schizophrenia

OBJECTIVE

To investigate the effect of loxapine on peripheral dopamine D2-like and serotonin receptor binding and on psychotic symptoms.

PATIENTS

Patients (n = 24) meeting the diagnostic criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, for schizophrenia were selected from an outpatient clinic (age range 18-70 yr).

METHODS

Patients were given loxapine (dose determined by a physician) for a period of 12 weeks. There were clinic visits at before treatment began and at 6 weeks and 12 weeks of treatment. Scores on a variety of efficacy and safety scales were recorded at each visit, and blood was drawn for receptor assays.

RESULTS

Patients showed significant improvement on most psychiatric assessment scales after 6 and 12 weeks of treatment with loxapine, and both lymphocyte D2-like and 5-HTL2A platelet receptor binding were down-regulated after 6 and 12 weeks. The degree of receptor down-regulation was not significantly correlated with improvements in psychotic symptoms, however.

CONCLUSION

Loxapine down-regulated both lymphocyte D2-like and platelet 5-HT2A receptors to the same extent, suggesting that both receptors are involved in the mechanism of action of loxapine in patients with schizophrenia.

Loxapine versus olanzapine in the treatment of delirium following traumatic brain injury

The use of typical neuroleptics has always been the mainstay of treatment for delirium following traumatic brain injury (TBI). Given the recent application of atypical neuroleptics to various psychiatric conditions formerly treated with typical neuroleptics, one questions whether this new class of drugs is superior to its predecessor in treating delirium post-TBI. We present a case of one patient with TBI-induced delirium where in fact the use of the typical mid-potency neuroleptic, loxapine, appeared to have a better clinical effect over the atypical neuroleptic, olanzapine.

[Self-poisoning with Datura stramonium. 3 case reports]

BACKGROUND

Datura stramonium is a hallucinogenic plant that causes serious poisoning. Due to its easy availability and strong anticholinergic properties, substance users and teens may use Datura stramonium as a drug. Consumption of any part of the plant can result in severe toxicity.

CASE REPORTS

3 cases of acute self-poisoning by ingestion of Datura stramonium are reported. The patients presented with a typical anticholinergic syndrome: agitation, confusion, hallucinations and combative behaviour; all of them had mydriasis, but dry mouth and tachycardia were less common. All these 3 subjects had a good prognosis but have required hospitalisation because of severe psychiatric derangement with agitated behaviour. The patients were favourably managed with only symptomatic treatment.

DISCUSSION

This article reviews the clinical syndrome associated with the toxicity. The severity of hallucinations and confusion, associated with pupillary dilation, flushing, dry mouth, and tachycardia, are related with Datura intoxication. Symptomatic treatment is efficient.

CONCLUSION

Primary care physicians might be informed about the abuse of Datura stramonium, often associated with substance misuse, and the need to educate risk-patients.

Loxapine for schizophrenia

BACKGROUND

Loxapine is a drug with D2/D3 receptor antagonist activity and a higher affinity for D3 than D2. Some authors have suggested that loxapine is more effective than typical antipsychotics in reducing the negative symptoms of schizophrenia, that extrapyramidal side-effects are not usually seen at clinically effective antipsychotic doses and that it should therefore be classed as atypical.

OBJECTIVES

To determine the effects of loxapine compared with placebo, typical and other atypical antipsychotic drugs for schizophrenia and related psychoses.

SEARCH STRATEGY

Electronic searches of Biological Abstracts (1980-1999), The Cochrane Library (Issue 1, 1999), The Cochrane Schizophrenia Group's Register (January 1999), EMBASE (1980-1999), MEDLINE (1966-1999), LILACS (1982-1996), PSYNDEX (1977-1995) and PsycLIT (1974-1999) were undertaken. In addition, pharmaceutical databases on the Dialog Corporation Datastar and Dialog services were searched. References of all identified studies were searched for further trials. Pharmaceutical companies and authors of trials were contacted.

SELECTION CRITERIA

All randomised controlled clinical trials relevant to the care of schizophrenia that compared loxapine to other treatments.

DATA COLLECTION AND ANALYSIS

Citations and, where possible, abstracts were independently inspected by reviewers, papers ordered, re-inspected and quality assessed. Data were independently extracted but excluded if loss to follow up was greater than 50%. For homogeneous dichotomous data the risk ratio (RR), 95% confidence interval (CI) and, where appropriate, the number needed to treat (NNT) were calculated on an intention-to-treat basis. For continuous data, weighted mean differences were calculated (WMD). All data were inspected for heterogeneity.

MAIN RESULTS

Compared to placebo, loxapine is antipsychotic (Global effect - not improved at 6 weeks, n=66, RR 0.6 CI 0.4-0.9 NNT 4 CI 2-62) with similar adverse effect profile to typical drugs. Is as effective as typical drugs in the short term (4-12 weeks) (Global effect - not improved, n=411, RR 0.89 CI 0.7-1.2). Very limited heterogeneous data suggest that, given intramuscularly (IM), loxapine may be at least as sedating as IM haloperidol and thiothixene.

REVIEWER'S CONCLUSIONS

Loxapine is antipsychotic but its effects are under researched. It is not clearly different from typical drugs in either its positive or adverse effects.

Pharmacologic and pharmacokinetic considerations in choosing an antipsychotic

Recent advances in our understanding of schizophrenia along with neuroscience insights into antipsychotic medication mechanisms of action have led to a renaissance in new drug development, including an expanded therapeutic spectrum encompassing more of the symptoms encountered in schizophrenia. Atypical antipsychotics, or new generation therapies, also demonstrate greater selectivity for therapeutic actions than for extrapyramidal symptoms (EPS). Our modern armamentarium of drugs spans a wide range of pharmacologies, and it is more accurate to envision shades of gray rather than a black-and-white description for typical versus atypical properties of medications. As our paradigms for antipsychotic efficacy have shifted, a reexploration of the "older" neuroleptics is warranted to determine if they possess pharmacologic attributes that might have been overlooked during the era of high-dose neuroleptic therapy. Loxapine appears to be in the center of this spectrum, somewhere between haloperidol and risperidone. Dosing implications for drugs with a more even serotonin-2A (5-HT2A) receptor and dopamine-2 (D2) receptor blocking effect are discussed. Loxapine might have a window of partial atypicality at doses < or = 50 mg/day. These lower doses might have potential as both monotherapy in responsive patients with persistent psychotic disorders and as an adjunctive treatment in partially responding patients on concurrent atypical antipsychotic treatments. The pharmacologic properties of loxapine within its usable dosage range are quite complex and are the net sum of the parent's plus metabolites' contributions (demethylation and hydroxylation by cytochrome P450 enzymes). These pharmacologic effects include alpha-adrenergic blockade, inhibition of the noradrenergic transporter protein (reuptake inhibition), and antimuscarinic effects. Drug interactions and cigarette smoking might alter the parent-to-metabolite concentration ratios, affecting the relative atypicality of this antipsychotic therapy. Moreover, with the intramuscular formulation, which does not undergo first-pass metabolism, the parent compound of loxapine, i.e., not its metabolites, is predominantly detected in the plasma of patients, reducing the likelihood for EPS during emergency interventions in patients with positive symptoms. Further study is warranted to determine loxapine's place in our treatment of schizophrenia.

The role of typical and atypical antipsychotic medications in the management of agitation and aggression

The management of agitation and aggression in psychiatric inpatients is a significant clinical dilemma. Establishing a clear diagnosis and distinguishing whether aggression is an acute manifestation or a long-standing or repetitive problem are fundamental antecedents of medication treatment. For acute aggression, either benzodiazepines or antipsychotic medications (typical and atypical) are recommended choices. Currently, on the basis of efficacy, ease of use, and availability in multiple (tablet, liquid, intramuscular) preparations, typical antipsychotics such as loxapine should be considered as first choice for acute aggression (in psychosis). On the other hand, atypical antipsychotics, particularly clozapine, should be considered when aggression in psychosis persists and/or is repetitive. Typical antipsychotics are indicated for persistent aggression in psychosis when medication noncompliance is the obstacle to effective treatment.

Does loxapine have "atypical" properties? Clinical evidence

Given findings at a pharmacologic level that loxapine has a ratio of serotonin (5-HT2) and dopamine (D2) binding affinity similar to that of the atypical antipsychotics, 1 review data at a clinical level to see if this agent has correlating effects on symptoms and behaviors. I conclude that there is reason to infer that loxapine may be more beneficial for negative symptoms and refractory states than other typical antipsychotic agents. However, because of the limitations within these older studies, controlled fixed-dose designs employing current outcome methodologies are needed before concluding that loxapine is an atypical antipsychotic agent.

Low-dose loxapine in the treatment of schizophrenia: is it more effective and more "atypical" than standard-dose loxapine?

Loxapine is chemically related to clozapine and shares with it and other atypical antipsychotic drugs relatively greater affinity for serotonin (5-HT)2A than for dopamine D2 receptors. However, as is the case for risperidone, the occupancy of 5-HT2A and D2 receptors can range from partial to full, depending upon the dose. It was, therefore, of interest to determine whether loxapine at low doses (< 50 mg/day) might be at least as or more effective and more tolerable than usual clinical doses (> or = 60 mg/day). We retrospectively examined data from 75 patients treated with loxapine and found psychopathology data from 10 and 12 patients treated with low-dose or standard-dose loxapine, respectively. No data were available on the other 53 patients, 28 of whom were initially treated with low-dose and 25 with standard-dose loxapine. For those treated for at least 6 weeks, there was evidence of equivalent efficacy for both low- and standard-dose loxapine with regard to improvement in Brief Psychiatric Rating Scale (BPRS) and Global Assessment Scale scores. There were 6 patients with a history of neuroleptic resistance among the 22 completers. Four of the low-dose group (40%) and 8 of the standard-dose group (67%) had at least a 20% decrease in BPRS total scores. Further study of the dose-response curve for loxapine and its usefulness in treating neuroleptic-resistant schizophrenia is indicated.

The role of alpha2-adrenoceptor antagonism in the anti-cataleptic properties of the atypical neuroleptic agent, clozapine, in the rat

1. The mechanism underlying the anticataleptic properties of the atypical neuroleptic agent, clozapine, has been investigated in the rat. 2.The close structural analogues of clozapine, loxapine (0.1 mg kg(-1) s.c.) and iso-clozapine (1 and 3 mg kg(-1) s.c.) induced catalepsy in rats. In contrast, clozapine and the regio-isomer of loxapine, iso-loxapine (up to 10 mg kg(-1) s.c.) did not produce catalepsy, but at a dose of 1 mg kg(-1) significantly inhibited catalepsy induced by loxapine (0.3 mg kg(-1) s.c.). 3. Radioligand binding assays showed that cataleptogenic potential was most clearly predicted by the D2/5-HT1A, D2/5-HT1B/1D and D2/alpha2-receptor affinity (KD) ratios: i.e. 30-100-fold higher ratios were calculated for loxapine and iso-clozapine, whereas the ratios were less than 1 for clozapine and iso-loxapine. The ratios of affinities for D2 to 5-HT2A, 5-HT2C or D1 did not reflect the grouping of cataleptic and non-cataleptic compounds. 4. Co-treatment with the alpha2-adrenoceptor antagonists, yohimbine (1-10 mg kg(-1) s.c.), RX 821002 (1-10 mg kg(-1) s.c.) and MK-912 (0.3 and 1 mg kg(-1) s.c.) dose-dependently inhibited the cataleptic response to loxapine (0.3 mg kg(-1)). Yohimbine (1-10 mg kg(-1) s.c.) also dose-dependently inhibited the cateleptic response to haloperidol (0.3 mg kg(-1) s.c.). The alpha2-adrenoceptor antagonists had no effect per se. 5. Neither yohimbine (10 mg kg(-1)) nor RX821002 (3 mg kg(-1)) altered the cataleptic response to the D1 receptor antagonist, SCH 23390 (1 mg kg(-1) s.c.), while, like clozapine, both compounds abolished the response to the 5-HT2A receptor antagonist, MDL 100,151 (3 mg kg(-1) s.c.). 6. The present data strongly implicate alpha2-adrenoceptor blockade in the anticataleptic properties of clozapine and suggest that its lack of extrapyramidal side effects in the clinic may also be a consequence of this property.

PET evidence that loxapine is an equipotent blocker of 5-HT2 and D2 receptors: implications for the therapeutics of schizophrenia

OBJECTIVE

Loxapine, a dibenzoxazepine antipsychotic, is closely related to clozapine and shares clozapine's high affinity for binding to serotonin 5-HT2 and dopamine D4 receptors. The purpose of this study was to document loxapine's 5-HT2 and D2 receptor occupancy in vivo in patients with psychoses.

METHOD

Ten patients who were taking loxapine (10-100 mg/day) had their D2 and 5-HT2 receptors assessed by means of positron emission tomography with [11C]raclopride and [18F]setoperone, respectively.

RESULTS

The D2 receptor occupancy ranged from 43% to 90%; 5-HT2 occupancy varied from 27% to near saturation. Statistical comparison of the results showed that loxapine was equipotent in blocking 5-HT2 and D2 receptors.

CONCLUSIONS

Loxapine differs from typical neuroleptics in demonstrating a high degree of 5-HT2 receptor occupancy. However, it is not "atypical" like clozapine and risperidone, since its 5-HT2 occupancy is not higher than its D2 occupancy. The results demonstrate that a high level of 5-HT2 occupancy is not a sufficient condition for atypicality. If atypical antipsychotic action is predicated on a combination of 5-HT2 and D2 effects, then it requires > 80% 5-HT2 occupancy in conjunction with < 80% D2 occupancy.

Lower plasma CC16, a natural anti-inflammatory protein, and increased plasma interleukin-1 receptor antagonist in schizophrenia: effects of antipsychotic drugs

Recently, it was suggested that in vivo activation of the monocytic and T-lymphocytic arms of cell-mediated immunity (CMI) may occur in schizophrenia and that antipsychotic drugs may modify CMI. The aim of the present study was to examine plasma soluble interleukin-2 receptor (sIL-2R), soluble suppressor/cytotoxic antigen (sCD8), interleukin-1 receptor antagonist (IL-1RA), and Clara cell protein (CC16) concentrations in normal controls, nonmedicated schizophrenic patients, and schizophrenic patients treated with risperidone or loxapine. Plasma concentrations of IL-1RA were significantly higher in nonmedicated schizophrenic patients than in normal controls. Plasma CC16 was significantly lower in nonmedicated and loxapine-treated schizophrenic patients than in normal controls, whereas risperidone-treated patients had plasma CC16 levels which were not significantly different from normal controls. Plasma CC16 levels were significantly and positively related to age at onset of schizophrenia. Plasma sIL-2R was significantly higher in schizophrenic patients who were treated with risperidone than in normal controls and nonmedicated schizophrenic patients. The results show that (i) schizophrenia is accompanied by an activation of the monocytic arm of CMI (i.e., increased plasma IL-1RA) and lower plasma levels of a natural anti-inflammatory and immunosuppressive agent, i.e. CC16, and that the latter may constitute a trait market of schizophrenia; and that (ii) chronic treatment with atypical antipsychotic agents, i.e., risperidone, may normalize lower plasma CC16 and increase plasma sIL-2R.

Treatment of the elderly suffering from psychosis and dementia

Studies with elderly demented subjects have suggested that overt hostility, agitation, hallucinosis, and hyperactivity are the most likely symptom profiles to respond to neuroleptics, but the available research data do not point to any one clear choice of medications. Meanwhile, recent government regulations require specific diagnosis-related indications for the use of neuroleptics. Unfortunately, there is still a general shortage of double-blind, placebo-controlled studies with either typical or atypical neuroleptics. Clinical treatment with neuroleptics requires careful evaluation of all extrapyramidal and possible cognitive side effects, especially with drugs having high anticholinergic potency. The long-term risk-benefit ratio for the use of typical or atypical neuroleptics in elderly demented patients is also uncertain, so adequate consideration should be given to non-neuroleptic medications before initiating a long-term trial of neuroleptics.

Emergence of symptoms of Tourette's syndrome during fluvoxamine treatment of obsessive-compulsive disorder

A 14-year-old boy with obsessive-compulsive disorder (OCD) developed, under fluvoxamine treatment, acute symptoms of Tourette's syndrome (TS) with aggravation of the OCD. The TS symptoms did not respond to dopamine blockers and disappeared only after withdrawal of fluvoxamine. Readministration of fluvoxamine caused a re-emergence of the same symptoms.

Aggression in the demented patient: a double-blind study of loxapine versus haloperidol

Aggression is common in dementia, with devastating social consequences. While high or low potency neuroleptics are the usual treatment of choice, they have been shown to yield inconsistent behavioral improvement and significant iatrogenic disability. This double-blind study was undertaken with aggressive demented patients to assess the efficacy and safety of a mid-potency neuroleptic, loxapine, in comparison to the more commonly prescribed high potency drug, haloperidol. Using an optimizing dosage regime, the outcome variables studied were aggression frequency and the number and nature of emergent side effects. Results demonstrated no significant difference regarding efficacy, but significantly fewer side effects with loxapine administration. The clinical and theoretical implications of these findings are discussed.

Neuroleptic malignant syndrome secondary to loxapine

Loxapine was introduced to the British market two years ago although it has been used in North America for eight years. We report the first probable case of neuroleptic malignant syndrome (NMS) secondary to loxapine in Britain. Two previous cases have been reported in North America (manufacturer's data).

Glycine adjuvant therapy to conventional neuroleptic treatment in schizophrenia: an open-label, pilot study

In an open-label study, glycine was administered orally (10.8 g/day in three divided doses) to six chronically psychotic patients, as an adjunct to conventional neuroleptic therapy, for periods extending from 4 days to 8 weeks. Glycine was administered in an effort to facilitate endogenous glutamatergic transmission at the level of the N-methyl-D-aspartate (NMDA) receptor complex, since a glutamatergic deficiency in the pathophysiology of schizophrenia has been postulated. Therapeutic efficacy was assessed with standardized psychiatric rating scales. Beneficial effects on behavioral symptomatology were observed in two patients, whereas two others worsened. In one of the two responders, clinical deterioration occurred after glycine withdrawal consistent with a positive adjuvant effect in this patient. However, glycine rechallenge in this patient was not associated with the clinical improvement seen during the initial glycine period. Clinical worsening was not observed after glycine discontinuation in the second responder. Glycine administration reduced neuroleptic-induced muscle stiffness and extrapyramidal dysfunction in three of the six patients. All patients tolerated the clinical trial. The limited penetrability of glycine across the blood-brain barrier is a major limitation of this approach to facilitating glutamatergic transmission at the level of the NMDA receptor complex.

Tardive myoclonus

We describe a 46-year-old, schizophrenic woman with late-onset myoclonus after treatment with antipsychotic drugs. The myoclonic jerking of the neck with synchronous contractions of the face persisted after all the antipsychotic drugs had been discontinued. Tardive myoclonus has not been documented previously.

A comparison of parenteral loxapine and haloperidol in hostile and aggressive acutely schizophrenic patients

In a parallel groups, double-blind study, 54 acutely psychotic schizophrenics were given loxapine or haloperidol parenterally for 24 to 72 hours, then orally for a total study period of up to 10 days. Dosage ratios of loxapine to haloperidol ranged from a minimum of 2.7:1 to a maximum of 4.4:1. Both groups showed significant and rapid improvement from baseline. Forty-eight percent of the loxapine patients and 33% of the haloperidol patients achieved and maintained a global severity of illness rating of mild or better. By the end of the study, 84% of the loxapine patients and 63% of the haloperidol patients had achieved an improvement rating of moderate or marked. This difference approached significance (p less than .10). The most frequently reported adverse experiences were dystonic reactions and akathisia. The number and severity of adverse experiences did not differ significantly between drug groups. Intramuscular loxapine was at least as effective as haloperidol in the initial management of hostile and aggressive schizophrenic patients. The maintenance of therapeutic response after conversion to oral concentrate was comparable with the two drugs.