No relationship between--141C Ins/Del polymorphism in the promoter region of dopamine D2 receptor and extrapyramidal adverse effects of selective dopamine D2 antagonists in schizophrenic patients: a preliminary study

Genetic Testing for Antipsychotic Pharmacotherapy: Bench to Bedside

There is growing research interest in learning the genetic basis of response and adverse effects with psychotropic medications, including antipsychotic drugs. However, the clinical utility of information from genetic studies is compromised by their controversial results, primarily due to relatively small effect and sample sizes. Clinical, demographic, and environmental differences in patient cohorts further explain the lack of consistent results from these genetic studies. Furthermore, the availability of psychopharmacological expertise in interpreting clinically meaningful results from genetic assays has been a challenge, one that often results in suboptimal use of genetic testing in clinical practice. These limitations explain the difficulties in the translation of psychopharmacological research in pharmacogenetics and pharmacogenomics from bench to bedside to manage increasingly treatment-refractory psychiatric disorders, especially schizophrenia. Although these shortcomings question the utility of genetic testing in the general population, the commercially available genetic assays are being increasingly utilized to optimize the effectiveness of psychotropic medications in the treatment-refractory patient population, including schizophrenia. In this context, patients with treatment-refractory schizophrenia are among of the most vulnerable patients to be exposed to the debilitating adverse effects from often irrational and high-dose antipsychotic polypharmacy without clinically meaningful benefits. The primary objective of this comprehensive review is to analyze and interpret replicated findings from the genetic studies to identify specific genetic biomarkers that could be utilized to enhance antipsychotic efficacy and tolerability in the treatment-refractory schizophrenia population.

Genetic variation and the risk of haloperidol-related parkinsonism in elderly patients: a candidate gene approach

Factors that influence the variation in occurrence of antipsychotic-related parkinsonism in elderly have not been well elucidated. The aim of this study was to investigate whether previous identified and studied genetic polymorphisms at DRD2, ANKK1, DRD3, HTR2A, HTR2C, RGS2, COMT, and BDNF genes are associated with antipsychotic-related parkinsonism in elderly patients.This cross-sectional study included 150 inpatients aged 65 years and older who were treated with haloperidol. Parkinsonism assessed by the Simpson Angus Scale was present in 46% of the included patients. The investigated predictors were polymorphisms in DRD2 (141CIns/Del and C957T), ANNK1 (TaqIA), DRD3 (Ser9Gly), HTR2A (-1438G>A and His452Tyr), HTR2C (Cys23Ser and -759C/T), RGS2 (+2971C>G), COMT (G158A), and BDNF (Val66Met). Frequencies of the -759 T allele of the HTR2C gene and the 158A allele of the COMT gene were significantly higher in patients without antipsychotic-induced parkinsonism (AIP) (nominal P = 0.03 and P = 0.02, respectively). -759 T allele carriership in females was associated with a lower risk of AIP (adjusted odds ratio, 0.31; 95% confidence interval, 0.11-0.85). The decrease in risk of AIP in carriers of the COMT 158A allele did not reach statistical significance. No significant associations were found between AIP and the remaining selected polymorphisms.Although validation is needed, this study suggests that carriership of the -759 T allele of the HTR2C gene in females may be protective against development of parkinsonism in elderly patients during treatment with haloperidol.

Bromperidol decanoate (depot) for schizophrenia

BACKGROUND

Antipsychotic drugs are the mainstay treatment for schizophrenia. Long-acting depot injections of drugs such as bromperidol decanoate are extensively used as a means of long-term maintenance treatment.

OBJECTIVES

To assess the effects of depot bromperidol versus placebo, oral antipsychotics and other depot antipsychotic preparations for people with schizophrenia in terms of clinical, social and economic outcomes.

SEARCH METHODS

For this 2012 update we searched the Cochrane Schizophrenia Group's Register (February 2012).

SELECTION CRITERIA

We sought all randomised trials focusing on people with schizophrenia where depot bromperidol, oral antipsychotics or other depot preparations. Primary outcomes were clinically significant change in global function, service utilisation outcomes (hospital admission, days in hospital), relapse.

DATA COLLECTION AND ANALYSIS

For the 2011 update MP independently extracted data, CEA carried out the reliability check. We calculated fixed-effect risk ratios (RR) and 95% confidence intervals (CI) for dichotomous data, and calculated weighted or standardised means for continuous data. Where possible, we calculated the number needed to treat statistic (NNT). Analysis was by intention-to-treat.For the 2012 update, data collection and analysis was not carried out as no new studies were found.

MAIN RESULTS

The 2012 search found no new studies, we have therefore included no new trials in this 2012 update. The number of included trials remain 4 RCTs, total n = 117. A single, small study of six months' duration compared bromperidol decanoate with placebo injection. Similar numbers left the study before completion (n = 20, 1 RCT, RR 0.4 CI 0.1 to 1.6) and there were no clear differences between bromperidol decanoate and placebo for a list of adverse effects (n = 20, 1 RCT, RR akathisia 2.0 CI 0.21 to 18.69, RR increased weight 3.0 CI 0.14 to 65.9, RR tremor 0.33 CI 0.04 to 2.69). When bromperidol decanoate was compared with fluphenazine depot, we found no important change on global outcome (n = 30, RR no clinical important improvement 1.50 CI 0.29 to 7.73). People allocated to fluphenazine decanoate and haloperidol decanoate had fewer relapses than those given bromperidol decanoate (n = 77, RR 3.92 Cl 1.05 to 14.60, NNH 6 CI 2 to 341). People allocated bromperidol decanoate required additional antipsychotic medication somewhat more frequently than those taking fluphenazine decanoate and haloperidol decanoate, but the results did not reach conventional levels of statistical significance (n = 77, 2 RCTs, RR 1.72 CI 0.7 to 4.2). The use of benzodiazepine drugs was very similar in both groups (n = 77, 2 RCTs, RR 1.08 CI 0.68 to 1.70). People left the bromperidol decanoate group more frequent than those taking other depot preparation due to any cause (n = 97, 3 RCTs, RR 2.17 CI 1.00 to 4.73). Anticholinergic adverse effects were equally common between bromperidol and other depots (n = 47, RR 3.13 CI 0.7 to 14.0) and additional anticholinergic medication was needed with equal frequency in both depot groups, although results did tend to favour the bromperidol decanoate group (n = 97, 3 RCTs, RR 0.80 CI 0.64 to 1.01). The incidence of movement disorders was similar in both depot groups (n = 77, 2 RCTs, RR 0.74 CI 0.47 to 1.17).

AUTHORS' CONCLUSIONS

Minimal poorly reported trial data suggests that bromperidol decanoate may be better than placebo injection but less valuable than fluphenazine or haloperidol decanoate. If bromperidol decanoate is available it may be a viable choice, especially when there are reasons not to use fluphenazine or haloperidol decanoate. Well-conducted and reported randomised trials are needed to inform practice.

Pharmacogenetics of response to antipsychotics in patients with schizophrenia

This review presents the findings of pharmacogenetic studies exploring the influence of gene variants on antipsychotic treatment response, in terms of both symptom improvement and adverse effects, in patients with schizophrenia. Despite numerous studies in the field, replicating findings across different cohorts that include subjects of different ethnic groups has been challenging. It is clear that non-genetic factors have an important contribution to antipsychotic treatment response. Differing clinical, demographic and environmental characteristics of the cohorts studied have added substantial complexity to the interpretation of the positive and negative findings of many studies. Pharmacogenomic genome-wide investigations are beginning to yield interesting data although they have failed to replicate the most robust findings of candidate gene studies, and are limited by the sample size, especially given the need for studying homogeneous cohorts. Most of the studies conducted on cohorts treated with single antipsychotics have investigated clozapine, olanzapine or risperidone response. These studies have provided some of the most replicated associations with treatment efficacy. Serotonergic system gene variants are significantly associated with the efficacy of clozapine and risperidone, but may have less influence on the efficacy of olanzapine. Dopamine D3 receptor polymorphisms have been more strongly associated with the efficacy of clozapine and olanzapine, and D2 genetic variants with the efficacy of risperidone. Serotonin influences the control of feeding behaviour and has been hypothesized to have a role in the development of antipsychotic-induced weight gain. Numerous studies have linked the serotonin receptor 2C (5-HT2C) -759-C/T polymorphism with weight gain. The leptin gene variant, -2548-G/A, has also been associated with weight gain in several studies. Pharmacogenetic studies support the role of cytochrome P450 enzymes and dopamine receptor variants in the development of antipsychotic-induced movement disorders, with a contribution of serotonergic receptors and other gene variants implicated in the mechanism of action of antipsychotics. Clozapine-induced agranulocytosis has been associated with polymorphisms in the major histocompatibility complex gene (HLA).

Bromperidol decanoate (depot) for schizophrenia

BACKGROUND

Antipsychotic drugs are the mainstay treatment for schizophrenia. Long-acting depot injections of drugs such as bromperidol decanoate are extensively used as a means of long-term maintenance treatment.

OBJECTIVES

To assess the effects of depot bromperidol versus placebo, oral antipsychotics and other depot antipsychotic preparations for people with schizophrenia in terms of clinical, social and economic outcomes.

SEARCH STRATEGY

For this 2011 update we searched the Cochrane Schizophrenia Group's Register (February 2011).

SELECTION CRITERIA

We sought all randomised trials focusing on people with schizophrenia where depot bromperidol, oral antipsychotics or other depot preparations. Primary outcomes were clinically significant change in global function, service utilisation outcomes (hospital admission, days in hospital), relapse.

DATA COLLECTION AND ANALYSIS

For this 2011 update MP independently extracted data, CEA carried out the reliability check. We calculated fixed-effect risk ratios (RR) and 95% confidence intervals (CI) for dichotomous data, and calculated weighted or standardised means for continuous data. Where possible, we calculated the number needed to treat statistic (NNT). Analysis was by intention-to-treat.

MAIN RESULTS

We have included no new trials in this 2011 update (4 RCTs, total n = 117). A single, small study of six months' duration compared bromperidol decanoate with placebo injection. Similar numbers left the study before completion (n = 20, 1 RCT, RR 0.4 CI 0.1 to 1.6) and there were no clear differences between bromperidol decanoate and placebo for a list of adverse effects (n = 20, 1 RCT, RR akathisia 2.0 CI 0.21 to 18.69, RR increased weight 3.0 CI 0.14 to 65.9, RR tremor 0.33 CI 0.04 to 2.69). When bromperidol decanoate was compared with fluphenazine depot, we found no important change on global outcome (n = 30, RR no clinical important improvement 1.50 CI 0.29 to 7.73). People allocated to fluphenazine decanoate and haloperidol decanoate had fewer relapses than those given bromperidol decanoate (n = 77, RR 3.92 Cl 1.05 to 14.60, NNH 6 CI 2 to 341). People allocated bromperidol decanoate required additional antipsychotic medication somewhat more frequently than those taking fluphenazine decanoate and haloperidol decanoate, but the results did not reach conventional levels of statistical significance (n = 77, 2 RCTs, RR 1.72 CI 0.7 to 4.2). The use of benzodiazepine drugs was very similar in both groups (n = 77, 2 RCTs, RR 1.08 CI 0.68 to 1.70). People left the bromperidol decanoate group more frequent than those taking other depot preparation due to any cause (n = 97, 3 RCTs, RR 2.17 CI 1.00 to 4.73). Anticholinergic adverse effects were equally common between bromperidol and other depots (n = 47, RR 3.13 CI 0.7 to 14.0) and additional anticholinergic medication was needed with equal frequency in both depot groups, although results did tend to favour the bromperidol decanoate group (n = 97, 3 RCTs, RR 0.80 CI 0.64 to 1.01). The incidence of movement disorders was similar in both depot groups (n = 77, 2 RCTs, RR 0.74 CI 0.47 to 1.17).

AUTHORS' CONCLUSIONS

Minimal poorly reported trial data suggests that bromperidol decanoate may be better than placebo injection but less valuable than fluphenazine or haloperidol decanoate. If bromperidol decanoate is available it may be a viable choice, especially when there are reasons not to use fluphenazine or haloperidol decanoate. Well-conducted and reported randomised trials are needed to inform practice.

The promise and reality of pharmacogenetics in psychiatry

Existing psychotropic medications for the treatment of mental illnesses, including antidepressants, mood stabilizers, and antipsychotics, are clinically suboptimal. They are effective in only a subset of patients or produce partial responses, and they are often associated with debilitating side effects that discourage adherence. There is growing enthusiasm in the promise of pharmacogenetics to personalize the use of these treatments to maximize their efficacy and tolerability; however, there is still a long way to go before this promise becomes a reality. This article reviews the progress that has been made in research toward understanding how genetic factors influence psychotropic drug responses and the challenges that lie ahead in translating the research findings into clinical practices that yield tangible benefits for patients with mental illnesses.

The promise and reality of pharmacogenetics in psychiatry

Existing psychotropic medications for the treatment of mental illnesses, including antidepressants, mood stabilizers, and antipsychotics, are clinically suboptimal. They are effective in only a subset of patients or produce partial responses, and they are often associated with debilitating side effects that discourage adherence. There is growing enthusiasm in the promise of pharmacogenetics to personalize the use of these treatments to maximize their efficacy and tolerability; however, there is still a long way to go before this promise becomes a reality. This article reviews the progress that has been made in research toward understanding how genetic factors influence psychotropic drug responses and the challenges that lie ahead in translating the research findings into clinical practices that yield tangible benefits for patients with mental illnesses.

Pharmacogenetic testing in schizophrenia and posttraumatic stress disorder

Genotyping patients prior to beginning psychiatric pharmacological therapy can serve to inform practitioners as to each patient's likelihood of therapeutic response and their relative risk of experiencing toxicity and other adverse side effects from certain drugs. Such information could arm physicians with the knowledge they need to make appropriate drug and dosing decisions and avoid the lengthy trial-and-error process with which they are faced today. This article describes the current state of pharmacogenetic testing in schizophrenia and posttraumatic stress disorder.

Polymorphism of dopamine D2 receptor (TaqIA, TaqIB, and-141C Ins/Del) and dopamine degradation enzyme (COMT G158A, A-278G) genes and extrapyramidal symptoms in patients with schizophrenia and bipolar disorders

The relationship is examined of the dopamine D2 receptor (DRD2) polymorphism (TaqIA, TaqIB, -141 C Ins/Del) and the catechol-O-methyltransferase (COMT) polymorphism (A-278G, G158A) to the risk of antipsychotic-induced extrapyramidal symptoms (EPS) in schizophrenia and bipolar disorders. Participants comprised 80 cases presenting with EPS (Simpson-Angus Scale score >3) and 188 controls presenting without EPS (Simpson-Angus Scale score <or=3) participated in this study. The COMT(L) allele conferred a reduction of EPS risk of 60% to heterozygotes, but the finding did not survive correction for multiple comparisons. In the bipolar subgroup, with a COMT(L) allele protection of 70%, the reduction remained significant after Bonferroni correction. The analysis of the COMT haplotypes revealed an association of the A-G haplotype with EPS risk in the overall group and the bipolar disorder subgroup, and an association of the A-A haplotype with EPS protection in the bipolar subgroup. No significant associations were found for DRD2 or COMT A-278G polymorphisms. This is the first report of an association between the COMT polymorphism and EPS susceptibility. These results are of interest in view of the increased use of antipsychotic drugs in bipolar patients in both the acute manic and the depressive phase.

Pharmacogenetics of parkinsonism, rigidity, rest tremor, and bradykinesia in African-Caribbean inpatients: differences in association with dopamine and serotonin receptors

We studied the association between polymorphisms of genes coding for dopamine D(2) (DRD2), dopamine D(3) (DRD3), serotonin 2(a) (HTR2A), and serotonin 2(c) (HTR2C) receptors and Antipsychotic-Induced Parkinsonism (AIP), rigidity, bradykinesia, and rest-tremor in African-Caribbeans treated with antipsychotics. Polymorphisms of DRD2 (-141CIns/Del, TaqIA, 957C > T), DRD3 (Ser9Gly), HTR2A (-1438A > G, 102T > C, His452Tyr), and HTR2C (-759C > T, Cys23Ser) genes were determined according to standard protocols. The Unified Parkinson Disease Rating Scale was used for the measurement of AIP, rigidity, bradykinesia, and rest-tremor. Chi-squared or Fisher's exact tests were applied for the association analyses. The t-test was applied for continuous data. Ninety nine males and 27 females met the inclusion criteria (Schizophr Res 1996, 19:195). In males, but not in females, there were significant associations between -141CDel-allele carriership (DRD2) and rigidity (Fisher's Exact Test: P = 0.021) and between 23Ser-allele carriership (HTR2C) and bradykinesia (P = 0.026, chi(2) = 5.0) or AIP (P = 0.008, chi(2) = 7.1). Rest-tremor was not associated with any of the polymorphisms studied. Analyses of the age, chlorpromazine equivalents, benztropine equivalents, the number of patients using anticholinergic medication, and the utilization patterns of the antipsychotic medication did not show statistically significant differences between patients with and without AIP, rigidity, bradykinesia, rest-tremor. Conducting the analysis without gender stratification did not affect our findings considerably, except for the association between bradykinesia and 23Ser-allele which failed to reach statistical significance in the total sample (P = 0.0646, chi(2) = 3.41). Since AIPs subsymptoms (rigidity, bradykinesia, and rest-tremor) may differ pharmacogenetically, our data strongly support symptom-specific analysis of AIP. However, further research is warranted to confirm our findings.

Pharmacogenetics of antipsychotic adverse effects: Case studies and a literature review for clinicians

There is a growing body of literature supporting the contribution of genetic variability to the mechanisms responsible for the adverse effects of antipsychotic medications particularly movement disorders and weight gain. Despite the current gap between research studies and the practical tools available to the clinician to identify such risks, it is hoped that in the foreseeable future, pharmacogenetics will become a critical aid to guide the development of personalized therapeutic regimes with fewer adverse effects. We provide a summary of two cases that are examples of using cytochrome P450 pharmacogenetics in an attempt to guide treatment in the context of recent literature concerning the role of pharmacogenetics in the manifestation of adverse effects of antipsychotic therapies. These examples and the review of recent literature on pharmacogenetics of antipsychotic adverse effects illustrate the potential for applying the principles of predictive, preventive, and personalized medicine to the therapy of psychotic disorders.

Polymorphisms in dopamine receptor DRD1 and DRD2 genes and psychopathological and extrapyramidal symptoms in patients on long-term antipsychotic treatment

DRD(1) and DRD(2) receptor gene variants have been associated with clinical aspects of schizophrenia; however only specific features were analyzed in different samples. To assess the complex interaction between genetic and clinical factors, we studied the possible cross-interactions between DRD1 and DRD2 dopamine receptor gene polymorphisms, symptomatology of schizophrenia and schizoaffective disorders, and the occurrence of treatment induced side effects taking into consideration possible clinical confounding variables. One hundred thirty one outpatients in stable remission meeting the DSMIV criteria for schizophrenia spectrum disorders and receiving long-term maintenance therapy with haloperidol, fluphenazine, zuclopenthixole, or risperidone were genotyped for DRD1 A-48G, DRD2 Ins-141CDel, and DRD2 Ser311Cys polymorphisms. Psychopathological symptoms were assessed with the positive and negative syndrome scale for schizophrenia (PANSS). Extrapyramidal side effects were assessed with the Simpson-Angus extrapyramidal side effects scale (EPS), the Barnes Akathisia scale (BARS), and the abnormal involuntary movement scale (AIMS). Drug dosage was included as covariant because it was associated with the severity of symptomatology, akathisia, and parkinsonism. No association was observed for DRD1 and DRD2 polymorphisms and extrapyramidal side effects, or with the other clinical variables considered. Our study suggests that DRD1 and DRD2 variants are not liability factors for tardive dyskinesia.

Pharmacogenetics and pharmacogenomics of schizophrenia: a review of last decade of research

The last decade of research into the pharmacogenetics of antipsychotics has seen the development of genetic tests to determine the patients' metabolic status and the first attempts at personalization of antipsychotic treatment. The most significant results are the association between drug metabolic polymorphisms, mainly in cytochrome P450 genes, with variations in drug metabolic rates and side effects. Patients with genetically determined CYP2D6 poor metabolizer (PMs) status may require lower doses of antipsychotic. Alternatively, CYP2D6 ultrarapid matabolizers (UMs) will need increased drug dosage to obtain therapeutic response. Additionally, polymorphisms in dopamine and serotonin receptor genes are repeatedly found associated with response phenotypes, probably reflecting the strong affinities that most antipsychotics display for these receptors. In particular, there is important evidence suggesting association between dopamine 2 receptor (D2) polymorphisms (Taq I and -141-C Ins/Del) and a dopamine 3 receptor (D3) polymorphism (Ser9Gly) with antipsychotic response and drug-induced tardive dyskinesia. Additionally, there is accumulating evidence indicating the influence of a 5-HT2C polymorphism (-759-T/C) in antipsychotic-induced weight gain. Application of this knowledge to clinical practice is slowly gathering pace, with pretreatment determination of individual's drug metabolic rates, via CYP genotyping, leading the field. Genetic determination of patients' metabolic status is expected to bring clinical benefits by helping to adjust therapeutic doses and reduce adverse reactions. Genetic tests for the pretreatment prediction of antipsychotic response, although still in its infancy, have obvious implications for the selection and improvement of antipsychotic treatment. These developments can be considered as successes, but the objectives of bringing pharmacogenetic and pharmacogenomic research in psychiatric clinical practice are far from being realized. Further development of genetic tests is required before the concept of tailored treatment can be applied to psychopharmatherapy. This review aims to summarize the key findings from the last decade of research in the field. Current knowledge on genetic prediction of drug metabolic status, general response and drug-induced side effects will be reviewed and future pharmacogenomic and epigenetic research will be discussed.

Association of DRD2 polymorphisms and chlorpromazine-induced extrapyramidal syndrome in Chinese schizophrenic patients

AIM

Extrapyramidal syndrome (EPS) is most commonly affected by typical antipsychotic drugs that have a high affinity with the D2 receptor. Recently, many research groups have reported on the positive relationship between the genetic variations in the DRD2 gene and the therapeutic response in schizophrenia patients as a result of the role of variations in the receptor in modulating receptor expression. In this study, we evaluate the role DRD2 plays in chlorpromazine-induced EPS in schizophrenic patients.

METHODS

We identified seven SNP(single nucleotide polymorphism) (-141Cins>del, TaqIB, TaqID, Ser311Cys, rs6275, rs6277 and TaqIA) in the DRD2 gene in 146 schizophrenic inpatients (59 with EPS and 87 without EPS according to the Simpson-Angus Scale) treated with chlorpromazine after 8 weeks. The alleles of all loci were determined by PCR (polymerase chain reaction).

RESULTS

Polymorphisms TaqID, Ser311Cys and rs6277 were not polymorphic in the population recruited in the present study. No statistical significance was found in the allele distribution of -141Cins>del, TaqIB, rs6275 and TaqIA or in the estimated haplotypes (constituted by TaqIB, rs6275 and TaqIA) in linkage disequilibrium between the two groups.

CONCLUSION

Our results did not lend strong support to the view that the genetic variation of the DRD2 gene plays a major role in the individually variable adverse effect induced by chlorpromazine, at least in Chinese patients with schizophrenia. Our results confirmed a previous study on the relationship between DRD2 and EPS in Caucasians.

Pharmacogenetics of schizophrenia

There is substantial unexplained interindividual variability in the drug treatment of schizophrenia. A substantial proportion of patients respond inadequately to antipsychotic drugs, and many experience limiting side effects. As genetic factors are likely to contribute to this variability, the pharmacogenetics of schizophrenia has attracted substantial effort. The approaches have mainly been limited to association studies of polymorphisms in candidate genes, which have been indicated by the pharmacology of antipsychotic drugs. Although some advances have been made, particularly in understanding the pharmacogenetics of some limiting side effects, genetic prediction of symptom response remains elusive. Nevertheless, with improvements in defining the response phenotype in carefully assessed and homogeneous subject groups, the near future is likely to see the identification of genetic predictors of outcome that may inform the choice of pharmacotherapy.

Pharmacogenetics as a tool in the therapy of schizophrenia

AIM

This review summarises the present knowledge of associations between pharmacogenetics and therapeutic efficacy and side effects of antipsychotics to enable pharmacists to judge the applicability for a more tailor made therapy in patients with schizophrenia. Polymorphisms of Cytochrome P450 isoenzymes and neurotransmitter receptors involved in the efficacy and side effects of antipsychotics are highlighted in this review.

METHOD

A search was performed in Medline and EMBASE for the period 1995-August 2002. Also relevant references from the selected papers were incorporated.

RESULTS

Poor metabolism with respect to CYP2D6 seems to be related with more pronounced extrapyramidal symptoms and more specifically with a higher incidence of tardive dyskinesia. The C/C-genotype for CYP1A2 results in smokers in a reduction of enzyme activity, but an effect on the incidence of tardive dyskinesia is controversial. For dopamine D2 receptors the effect of the -141C Ins/Del polymorphism on efficacy is not clear yet, although the Taq I polymorphism is associated with greater improvement of positive, but not negative symptoms in acute psychosis. The Gly9-allele of the dopamine D3 receptor is associated with the response to clozapine, but in studies in which the choice of antipsychotics is not restricted, the role of this polymorphism is unclear. The reverse is applicable to the dopamine D(4.2/4.7) polymorphism. For the 5-HT2A receptor the His452Tyr polymorphism is associated with response to clozapine, the 102 T/C polymorphism leads to equivocal results. The polymorphism studied for 5-HT5A, 5-HT6, alpha1A- and alpha2A-receptors give no clear associations with the response to clozapine. The polymorphism studied of the dopamine D2 and D4 receptor are not related to extrapyramidal adverse effects and side effects, respectively. The 9Gly-variant of the dopamine D3 receptor, the 102C-variant, but not the His452Tyr polymorphism of the 5-HT2A-receptor and the 23Ser-variant (for females only) of the 5-HT2C receptor seem to increase the susceptibility to tardive dyskinesia. Weight gain induced by antipsychotics seems to be associated with the -759C-allele of the 5-HT2C receptor.

CONCLUSION

The results show the first careful steps toward application of pharmacogenetics in a more individualised, tailor-made, pharmacotherapy. A pre-condition seems to be a multifactorial approach, as can be expected for multifactorial processes.

Response to chlorpromazine treatment may be associated with polymorphisms of the DRD2 gene in Chinese schizophrenic patients

Previous studies have demonstrated that the -141C Ins/Del and TaqI A polymorphisms in the DRD2 gene affect the density of the dopamine D2 receptor. The present study examines the correlation between these two polymorphisms and the therapeutic response to chlorpromazine, a typical antipsychotic drug, in 135 inpatients with schizophrenia. Clinical symptoms were evaluated using the Brief Psychiatry Rating Scale (BPRS) before and after 8 weeks of treatment with 300-600 mg/day of chlorpromazine. Our results show that genotyping -141C Ins/Del may help to predict the efficacy of chlorpromazine treatment (P=0.01) due to the fact that patients with no Del allele showed greater improvement than those with Del allele on the overall BPRS (P=0.03), and that, therefore, the potential for therapy in patients with schizophrenia is related to the -141C Ins/Del polymorphism in the DRD2 gene. However, no such relationship was found for the TaqI A polymorphism.

The characteristics of side-effects of bromperidol in schizophrenic patients

The characteristics of the side-effects of bromperidol was investigated in 33 acutely exacerbated schizophrenic patients. The most frequently observed side-effects were extrapyramidal symptoms. Acute dystonia developed in 10 of 33 patients, and the mean age was significantly lower (P < 0.05) in patients with dystonia (27.3 +/- 6.2 years) than that in patients without dystonia (41.5 +/- 12.9 years). Plasma drug concentrations were not associated with side-effects. These findings suggest that acute dystonia is affected by age factor, and that daily dosage or monitoring of drug concentration is unlikely to be a useful marker for the prediction of side-effects during bromperidol treatment.