Clozapine versus typical antipsychotics a retro- and prospective study of extrapyramidal side effects

Schizophrenic patients in long-term neuroleptic monotherapy with clozapine (n=100) and perphenazine, flupenthixol or zuclopentixol (controls,n=100) were evaluated for extrapyramidal side effects (EPS) (blind) as well as other side effects and mental condition (non-blind). In both groups the patients had received neuroleptic treatment for a total of 14 years (median) and the present antipsychotic (clozapine or control drug) for 5 years. Thus the clozapine-treated patients had previously received traditional neuroleptics for 9 years (median). The study was both retrospective (0.3–19 years for clozapine, 0.3–24 years for control drug, by means of chart information) and prospective (1 year, with video-controlled evaluation of EPS). There was a significantly lower prevalence of tardive dyskinesia (TD) in clozapine treated patients than control patients, although prior to this treatment there were more TD patients in the clozapine group (P<0.05). This lower level of TD in the clozapine group was related to a lower induction of new cases (P<0.001) and a tendency towards greater disappearance of TD in the clozapine than in the control group (P=0.07). Clozapine treated patients without TD had started clozapine and ceased traditional neuroleptics at an earlier age than those with TD. Parkinsonian signs were seen in 33% of the clozapine patients versus 61% of the control patients, mainly as hypokinesia; tremor in 3% versus 11% and rigidity in 0 versus 19%. Psychic akathisia was found in 14% versus 40% and motor akathisia in 7% versus 29% of the patients, all differences significantly in favor of clozapine. Clozapine treated patients also had less neuroleptic-induced emotional indifference and depression, but more autonomic side effects than controls.     

Drug extrapyramidal side effects. CYP2D6 genotypes and phenotypes

Objective: Among Caucasians, a lack of cytochrome P ₄₅₀ enzyme CYP2D6 is observed in 5–10% of individuals, named poor metabolizers (PMs). A consequence may be an impaired metabolism of many drugs such as most of the psychotropic drugs with an increased risk of drug side effects. This enzyme is also involved in the metabolism of endogenous compounds, including neurotransmitters such as dopamine and dopamine-related neurotransmitters which play a role in the mechanism of action of extrapyramidal drug side effects. The present study investigates whether patients who have developed and those who have not developed extrapyramidal drug side effects differ in their CYP2D6 genotypes and phenotypes. Methods: The CP2D6 genotype (method involving restriction length fragment polymorphism and polymerase chain reaction-single strand conformation polymorphism) was determined in 65 drug-treated in-patients, and the CYP2D6 phenotype (with dextromethorphan probe) in 62 of them. Two groups were constituted, one with 22 patients who had developed extrapyramidal drug side effects, and the second with 43 patients without such side effects. Results: In the whole population, there was an over-representation of PM phenotypes – more marked in the first group than the second (45% vs 14%). Concerning the genotypes, we observed that the percentage of functional alleles (with extensive metabolic capacity) was higher in group 2, whereas the percentage of non-functional alleles (without metabolic activity) was higher in group 1; this frequency difference was only marginally significant (χ² 5.95; P < 0.0509; degrees of freedom=2). Consequently, there was a higher percentage of genotypes with no (extensive) functional alleles in the group of patients suffering from extrapyramidal side effects than in the other group (P < 0.00001). Conclusion: CYP2D6-impaired metabolic capacity may be a contributory factor in extrapyramidal drug side effects. Received: 25 May 1999 / Accepted in revised form: 18 August 1999     

The effect of vitamin E addition to acute neuroleptic treatment on the emergence of extrapyramidal side effects in schizophrenic patients: An open label study

The anti-oxidant vitamin E has been reported to be effective in the treatment of tardive dyskinesia. The present open label study examined the effect of supplemental therapy with vitamin E on acute extrapyramidal symptoms and cell enzymes in patients receiving neuroleptic drugs. Thirty-nine hospitalized schizophrenic patients were randomly assigned to two groups: group 1 (n=20) was treated with neuroleptics, and group 2 (n=19) with neuroleptics combined with a fixed dose of vitamin E (600 IU/day), administered for two weeks. All patients were assessed with the Simpson-Angus Rating Scale (Simpson and Angus, 1970) for neuroleptic induced Parkinsonism (NIP), Barnes’ Akathisia Scale ( Barnes, 1989), and Brief Psychiatric Rating Scale: laboratory parameters included serum creatine kinase (CK) activity, serum glutamate oxaloacetic transaminase (SGOT) and white blood cell count (WBC). The addition of vitamin E to neuroleptic agents was associated with a trend (p=0.08) towards prevention of the emergence of NIP compared to neuroleptic treatment alone. Addition of vitamin E to neuroleptics may reduce the severity of acute NIP in schizophrenic patients.     

Serotonin and dopamine receptor gene polymorphisms and the risk of extrapyramidal side effects in perphenazine-treated schizophrenic patients

RATIONALE: Perphenazine, a classical antipsychotic drug, has the potential to induce extrapyramidal side effects (EPS). Dopaminergic and serotonergic pathways are involved in the therapeutic and adverse effects of the drug. OBJECTIVES: To evaluate the impact of polymorphisms in the dopamine D(2) and D(3) and serotonin 2A and 2C receptor genes (DRD2, DRD3, HTR2A, and HTR2C) on short-term effects of perphenazine monotherapy in schizophrenic patients. MATERIALS AND METHODS: Forty-seven Estonian inpatients were evaluated before and after 4-6 weeks of treatment by Simpson-Angus rating scale, Barnes scale, and Positive and Negative Symptom Scale. Genotyping was performed for common DRD2, DRD3, HTR2A, and HTR2C gene polymorphisms, previously reported to influence receptor expression and/or function. RESULTS: Most of the patients (n = 37) responded to the treatment and no significant association was observed between the polymorphisms and antipsychotic response. The 102C allele of HTR2A and the -697C and 23Ser alleles of HTR2C were more frequent among patients with EPS (n = 25) compared to patients without EPS (n = 22) (p = 0.02, 0.01, and 0.02, respectively). The difference between patients with and without EPS in variant allele frequencies remained significant after multiple model analyses including age, gender, and duration of antipsychotic treatment as covariants. There was no significant association between EPS occurrence and polymorphisms in the DRD2 and DRD3 genes. CONCLUSIONS: An association was observed between polymorphisms in HTR2A and HTR2C genes and occurrence of acute EPS in schizophrenic patients treated with perphenazine monotherapy. Larger study populations are needed to confirm our findings.     

Catalepsy as a rodent model for detecting antipsychotic drugs with extrapyramidal side effect liability

The predictive validity of catalepsy as a rodent model for detecting the extrapyramidal side effects (EPS) of antipsychotic drugs was recently questioned when the novel antipsychotic savoxepine produced little catalepsy in rodents while producing significant EPS in schizophrenic patients. Because catalepsy is viewed as an important model for predicting EPS, we decided to re-evaluate the effects of savoxepine. Savoxepine, clozapine, haloperidol, olanzapine, ORG 5222, raclopride, and risperidone were examined in two tests for catalepsy (grid and bar tests) in male Sprague-Dawley rats. The ability to antagonize amphetamine-induced hypermotility was also examined, since this measure is believed to predict clinical efficacy. With the exception of clozapine, all drugs produced dose-dependent catalepsy in both tests. For each drug, the minimum effective dose for producing catalepsy was greater than or equal to the ED₅₀ for antagonizing amphetamine-induced hyperactivity (defined as the dose producing a 50% reduction in hyperactivity). Clozapine resulted in the widest separation of effective doses in the catalepsy and activity models. Raclopride produced the next largest separation while the remaining drugs resulted in only a one-or two-fold dose separation between the two behavioral tests. The results with haloperidol and clozapine are consistent with the clinical effects of these drugs (severe versus mild EPS). The ratios of effective doses in catalepsy and activity for the remaining novel drugs are also consistent with preliminary clinical findings indicating some EPS with each of these compounds. Thus, catalepsy remains a suitable rodent model for detecting compounds with EPS liability in humans.     

Differential reversal of various dopamine antagonists by anticholinergics in sidman avoidance: possible relationship to adrenergic blockade

Various dopamine receptor antagonists have divergent clinical and neurochemical properties. The relative ability of anticholinergics (benztropine and scopolamine) to reverse these drugs was assessed in squirrel monkeys and rats performing a Sidman avoidance task. In monkeys, benztropine markedly attenuated the effects of oxiperomide, metoclopramide, halopemide, tiapride and mezilamine as well as haloperidol. Chlorpromazine and fluphenazine were antagonized to a moderate extent; thioridazine and perlapine were not antagonized; and clozapine was actually potentiated by benztropine. In the rat, benztropine antagonized haloperidol strongly but reversed fluphenazine, thioridazine or clozapine only weakly or not at al. The overall effects of scopolamine in both species were similar to those of benztropine. The dopamine receptor antagonists that were most completely reversed by benztropine were found to inhibit ³H-spiroperidol more strongly than ³H-WB-4101 binding in calf caudate, while the reverse was true for drugs that were antagonized only moderately or not at all by benztropine. These results support a previous suggestion that anticholinergic reversal is less marked aginst dopamine antagonists with alpha-adrenergic blocking properties. Benztropine reversal of experimental dopamine receptor antagonists in the squirrel monkey Sidman avoidance test may contribute to their preclinical characterization.     

Correlation of thiothixene serum levels and age

Two experiments are reported in which acute single test dose levels of thiothixene (Navane) were correlated with age. In the first study 20 mg oral doses were given to 28 male subjects and serum levels were drawn 2 h later. Mean age was 30 and correlation of serum level with age was 0.43, P<0.02. In a second older group with a mean age of 41, 10 mg oral doses were given to 25 subjects. A correlation with age of 0.41, P<0.05 was obtained with age. In prior work such acute levels have been found to correlate with steady-state serum levels and with clinical response to the medication. Few side-effects were seen in these populations and no correlations were obtained between serum levels and any side-effects.     

Peripheral and central muscarinic receptor affinity of psychotropic drugs

Summary The muscarinic receptor affinity of 27 psychotropic and 5 anticholinergic substances was examined in 2 in-vivo and 2 in-vitro models. A highly significant correlation was obtained between the effect of all compounds examined on the atropine sensitive binding of ³H-PrBCM and the effect in the conventional guinea-pig ileum preparation. Antagonism of oxotremorine induced tremors in mice by anticholinergics and neuroleptics was also significantly correlated to the corresponding data obtained in the in-vitro tests. Due to very low potency in the physostigmine induced mortality test in mice too few ED50 values were obtained to perform statistical comparisons.It is concluded, that the conventional guinea-pig ileum model and the ³H-PrBCM binding model are equally predictive as tests for antimuscarinic properties. When in-vivo anticholinergic data for neuroleptics are used it must be considered that a possible dopamine receptor blockade may diminish the antimuscarinic effect of the substance.     

Cerebrospinal fluid homovanillic acid and hypokinetic side effects of neuroleptics

Eleven psychotic patients treated with neuroleptics for 1 month showed a relatively poor response, more side effects, and a no-tolerance pattern with respect to cerebrospinal fluid (CSF) homovanillic acid (HVA). Within this group the severity of neuroleptic catatonia and Parkinsonian side effects was positively associated with an increase in CSF HVA turnover during the treatment period.     

Further evidence for the association between 5-HT2C receptor gene polymorphisms and extrapyramidal side effects in male schizophrenic patients

Rationale Antipsychotic-induced extrapyramidal side effects (EPS) are still a major problem in the treatment of schizophrenia. Serotonin 2C receptors (5-HT_2C) have regulatory effects on dopaminergic pathways in brain regions involved with EPS. Polymorphisms in the 5-HT_2C gene (HTR2C) have been suggested to be associated with the risk of developing EPS. Objective Our purpose was to evaluate the impact of polymorphisms in the HTR2C gene on the occurrence of EPS in male schizophrenic patients. Methods Ninety-nine male Caucasian chronic schizophrenic patients on long-term treatment with classical antipsychotics were genotyped for the −997 G/A, −759 C/T, −697 G/C and Cys23Ser polymorphisms of HTR2C. EPS (dystonia, parkinsonism, tardive dyskinesia) were assessed by the Simpson-Angus Scale and the Abnormal Involuntary Movement Scale. Fifty-one patients had current or previous history of EPS, whereas 48 patients had no symptoms or history of EPS. To rule out a possible association between HTR2C polymorphisms and schizophrenia, 112 healthy male volunteers were also genotyped. Results Allele frequencies of −997A, −759T and −697C did not differ between the groups, whereas patients with EPS had a significantly (p = 0.025) higher frequency of the 23Ser allele (0.29) than did patients without EPS (0.15) or healthy volunteers (0.13). A similar trend was observed for a haplotype including the −997G, −759C, −697C and 23Ser alleles (p = 0.04). Conclusions Results confirm previously reported associations between the HTR2C 23Ser allele and EPS occurrence and suggest the novel finding of an HTR2C haplotype association with EPS in male chronic schizophrenic patients.     

Serum neuroleptic concentrations and clinical response: A radioreceptor assay investigation of acutely psychotic patients

Twenty-two acutely psychotic patients were rigorously assessed for psychopathology at baseline and after 14 days of neuroleptic treatment. The neuroleptic radioreceptor assay (NRRA) was used to determine serum neuroleptic concentrations. Serum neuroleptic concentration was significantly, nonlinearly related to changes in BPRS Total Score, and BPRS Factor Scores for Thought Disturbance and Anxiety-Depression. Clinical improvement was associated with intermediate (11–50, 51–126 ng/ml haloperidol equivalents) while poor clinical outcome was related to both low (less than or equal to 10 ng/ml) or high (greater than 125 ng/ml) serum levels. The results are discussed in terms of a possible therapeutic window for the neuroleptics and the implications this might have for clinical practice.     

The attenuating effect of carteolol hydrochloride, a β-adrenoceptor antagonist, on neuroleptic-induced catalepsy in rats

It is known that β-adrenoceptor antagonists are effective in the treatment of akathisia, one of the extrapyramidal side effects that occur during neuroleptic treatment. Neuroleptic-induced catalepsy, a model of neuroleptic-induced extrapyramidal side effects, was considered suitable as a model for predicting neuroleptic-induced akathisia in humans, although neuroleptic-induced catalepsy was not considered a specific test for neuroleptic-induced akathisia. Therefore, the effects of carteolol, a β-adrenoceptor antagonist, on haloperidol-induced catalepsy in rats were behaviorally studied and compared with those of propranolol and biperiden, a muscarinic receptor antagonist. Carteolol, as well as propranolol and biperiden, inhibited the haloperidol-induced catalepsy. The inhibitory effect of carteolol was almost comparable to that of propranolol, but was weaker than that of biperiden. Carteolol did not evoke postsynaptic dopamine receptor-stimulating behavioral signs such as stereotypy and hyperlocomotion in rats. Carteolol did not antagonize the inhibitory effects of haloperidol on apomorphine-induced stereotypy and locomotor activity in rats. In addition, carteolol did not evoke 5-HT_1A receptor-stimulating behavioral signs such as flat body posture and forepaw treading and did not inhibit 5-hydroxytryptophan-induced head twitch in rats. Finally, carteolol did not inhibit physostigmine-induced lethality in rats. These results strongly suggest that carteolol improves haloperidol-induced catalepsy via its β-adrenoceptor antagonistic activity and is expected to be effective in the treatment of akathisia without attenuating neuroleptic-induced antipsychotic effects due to its postsynaptic dopamine receptor antagonistic activity. Received: 7 March 1996/ Final version: 27 November 1996     

Fluphenazine levels during maintenance treatment of recent-onset schizophrenia: relation to side effects, psychosocial function and depression

Rationale: The utility of fluphenazine levels during maintenance treatment of schizophrenia is still unclear. Objectives: This study investigated the relationship between fluphenazine levels and a variety of clinical measures during maintenance treatment of schizophrenia. Methods: Fluphenazine levels, side effects, depression and psychosocial outcome were measured at five time points over approximately 1 year in 59 recent onset schizophrenic patients treated with a maintenance dose of injectable fluphenazine decanoate. Negative symptoms were evaluated at the 1-year endpoint. Results: Fluphenazine levels showed marked intraindividual variability even when measurements were restricted to the second 6 months of treatment, by which time steady state levels should have been achieved. No consistent relationship was found between fluphenazine levels and any of the outcome measures. Conclusions: The results of this study suggest that fluphenazine plasma levels do not routinely add relevant clinical information beyond that of dose in evaluating potential side effects or negative consequences during maintenance treatment with the decanoate form of the medication. Received: 28 January 1999 / Final version: 20 September 1999     

Interactions between neuroleptics and 5-HT1A ligands in preclinical behavioral models for antipsychotic and extrapyramidal effects

Rationale: Combining neuroleptics with 5-HT_1A ligands is thought to improve the preclinical profile of neuroleptics and may be of interest in the development of new compounds that have greater therapeutic potential and/or are better tolerated. Objective: To examine 1) the ability of 5-HT_1A ligands to alter the effects of neuroleptics in preclinical models for antipsychotic potential (hindlimb retraction time in the paw test) and extrapyramidal side-effects (forelimb retraction time in the paw test; catalepsy tests), 2) the role of intrinsic activity at 5-HT_1A receptors in the modulatory effects of 5-HT_1A ligands, and 3) the generality of the interactions across neuroleptics. Methods: The effects of different doses of 5-HT_1A ligands with intrinsic activity ranging from high (e.g., 8-OH-DPAT) to low (e.g., WAY 100135) administered together with a fixed, high dose of the neuroleptics haloperidol, risperidone, and tropapride were examined in the paw test and on catalepsy. Results: Firstly, the 5-HT_1A agonists 8-OH-DPAT and ipsapirone attenuated the extrapyramidal-like effects of haloperidol and risperidone more than their therapeutic-like effects; this was not observed for tropapride, where all of its effects were markedly attenuated. Secondly, neither the weak 5-HT_1A agonist WAY 100135 nor the silent antagonist WAY 100635 attenuated the effects of neuroleptics. Thirdly, neuroleptics apparently differed in their sensitivity to interactions with 5-HT_1A agonists inasmuch as 8-OH-DPAT and ipsapirone attenuated the effects of tropapride on hindlimb retraction times more than those of haloperidol or risperidone. Conclusions: The present data suggest that 5-HT_1A agonists with intermediate or high, but not low, intrinsic activity may abolish the extrapyramidal effects of neuroleptics. Together with results of previous studies, it appears that 5-HT_1A agonists alter the antipsychotic-like effects of neuroleptics, although this may depend on the neuroleptic studied. Received: 29 June 1998/Final version: 6 November 1998     

Efficacy of nefazodone in the treatment of neuroleptic induced extrapyramidal side effects: a double-blind randomised parallel group placebo-controlled trial

Many atypical antipsychotics show antagonism at both serotonergic and dopaminergic neurones and show fewer extrapyramidal side effects (EPS). Nefazodone blocks postsynaptic 5HT2A receptors and weakly inhibits serotonin reuptake. This study aimed to elucidate the role of nefazodone in the treatment of antipsychotic-induced EPS. The trial was a double-blind, randomised, placebo-controlled trial of patients requiring antipsychotic treatment with haloperidol 10mg daily; from which a subgroup of patients who developed EPS were selected for the study. Patients were randomised to add-on therapy with either placebo (n=24) or nefazodone (n=25) 100mg bd. EPS were measured on days 0, 3 and 7 using the Simpson Angus, Barnes akathisia, abnormal involuntary movement and Chouinard scales. Nefazodone significantly reduced EPS as measured by both the Simpson Angus scale and CGI (p=0.007 and 0.0247, respectively). Akathisia and tardive dyskinesia did not differ between the two groups (p=0.601; p=0.507, respectively). These results suggest the role of 5HT2 antagonism in the mechanism of action of atypical antipsychotics with respect to lowering rates of drug-induced EPS. In addition, a therapeutic role for nefazodone is suggested in the treatment of antipsychotic-induced EPS.     

Rapid induction of extrapyramidal side effects with combined use of lithium and neuroleptics

Various forms of toxicity have been described when lithium and neuroleptics are used in combination. Two cases are presented in which extrapyramidal symptoms appeared soon after lithium was added to a regimen of neuroleptics. Clinical variables and pathophysiologic mechanisms are discussed. This reaction warrants further investigation.     

Effect of switching carbamazepine to oxcarbazepine on the plasma levels of neuroleptics. A case report

Carbamazepine was switched to its 10-keto analogue oxcarbazepine among six difficult-to-treat schizophrenic or organic psychotic patients using concomitantly haloperidol, chlorpromazine or clozapine. This change resulted within 2–4 weeks in the 50–200% increase in the plasma levels of these neuroleptics and the appearance of extrapyramidal symptoms. None of the patients showed any clinical deteriotation during the following 3–6 months. The results of this case report support the idea that in contrast with carbamazepine oxcarbazepine does not induce the hepatic microsomal enzyme systems regulating the inactivation of antipsychotic drugs.     

Potential side effects to GLP-1 agonists: understanding their safety and tolerability

Introduction: Glucagon-like peptide 1 receptor (GLP-1Rx) agonists might elicit unwelcome side effects and concerns have recently been raised about their safety.

Areas covered: Available evidence about safety, tolerability and potential adverse events relative to GLP-1Rx agonists presently used. We searched the MEDLINE database using the terms: ‘GLP-1 receptor agonists’, ‘Incretin therapy side effects’, ‘exenatide’, ‘ liraglutide’, ‘exenatide long-acting release’, ‘lixisenatide’. Articles were selected on the basis of the study design and importance, in the light of authors’ clinical experience and personal judgment. The main safety concern about GLP-1Rx agonists use is the possible association with increased risk of pancreatitis and/or tumors. This concern stems mainly from limited observations in animal models not confirmed in similar studies. Furthermore, clinical studies reporting association between GLP-1Rx agonist use and pancreatitis/cancer are marred by several biases and both clinical trials and post-marketing analyses failed to demonstrate a significant association.

Expert opinion: As stated by both FDA and EMA, the safety concerns emerged so far about GLP-1RX agonists should not affect present prescribing habits. Thus, although a strict data monitoring must be encouraged, they should not prevent access to the benefits of an innovative treatment, such as GLP-1Rx agonists use, to a large diabetic population still confronted with unmet needs.     

The risk of cardiovascular side effects with anti-anginal drugs

ABSTRACT

Introduction: Angina pectoris is a common presenting symptom of underlying coronary artery disease or reduced coronary flow reserve. Patients with angina have impaired quality of life; and need to be treated optimally with antianginal drugs to control symptoms and improve exercise performance. A wide range of antianginal medications are approved for the treatment of angina, and often more than one class of antianginal drugs are used to adequately control the symptoms. This expert opinion highlights the likely cardiac adverse effects of available antianginal drugs, and how to minimize these in individual patients and especially during combination treatment.

Areas covered: All approved antianginal drugs, including the older and newly approved medications with different mechanism of action to the older drugs as well as some of the unapproved herbal medications. The safety profiles and potential cardiac side effects of these medications when used as monotherapy or as combination therapy are discussed and highlighted.

Expert opinion: Because of the different cardiac safety profiles and possible side effects, we recommend selection of initial drug or adjustment of therapy based on the resting heart rate; blood pressure, hemodynamic status; and resting left ventricular function, concomitant medications and any associated comorbidities.