Metabolic interaction between amitriptyline and perphenazine in psychiatric patients

Perphenazine for schizophrenia

BACKGROUND

Perphenazine is an old phenothiazine antipsychotic with a potency similar to haloperidol. It has been used for many years and is popular in the northern European countries and Japan.

OBJECTIVES

To examine the clinical effects and safety of perphenazine for those with schizophrenia and schizophrenia-like psychoses.

SEARCH METHODS

We updated our original search using the Cochrane Schizophrenia Group's register (September 2013), references of all included studies and contacted pharmaceutical companies and authors of included studies in order to identify further trials.

SELECTION CRITERIA

We included all randomised controlled trials that compared perphenazine with other treatments for people with schizophrenia and/or schizophrenia-like psychoses. We excluded trials of depot formulations of perphenazine.

DATA COLLECTION AND ANALYSIS

Two review authors independently inspected citations and, where possible, abstracts. We ordered papers, inspected and quality assessed them. We extracted data, again working independently. If loss to follow-up was greater than 50% we considered results as 'prone to bias'. For dichotomous data, we calculated risk ratios (RR) and for continuous data we calculated mean differences (MD), both with the 95% confidence intervals (CI). We assessed quality of data using the GRADE (Grading of Recommendations Assessment, Development and Evaluationtool) and assessed risk of bias for included studies.

MAIN RESULTS

Thirty-one studies fulfilled the inclusion criteria, with a total of 4662 participants (of which 4522 were receiving the drugs relevant to our comparison) and presented data that could be used for at least one comparison. The trial centres were located in Europe (especially Scandinavia), Japan and Northern America.When comparing perphenazine with placebo, for our primary outcome of clinical response, results favoured perphenazine with significantly more people receiving placebo rated as either 'no better or deterioration' for global state than people receiving perphenazine (1 RCT, n = 61 RR 0.32 CI 0.13 to 0.78, very low quality evidence). More people receiving placebo relapsed, although not a statistically significant number (1 RCT, n = 48, RR 0.14 CI 0.02 to 1.07, very low quality evidence). Death was not reported in the perphenazine versus placebo comparison. Experiences of dystonia were equivocal between groups (1 RCT, n = 48, RR 1.00 CI 0.07 to 15.08, very low quality evidence); other outcomes not reported in this comparison include serious adverse events, economic outcomes, and service use and hospitalisation.For the comparison of perphenazine versus any other antipsychotic drugs, no real differences in effect between the drugs were found. There was no significant difference between groups for those considered 'no better or deterioration' (17 RCTs, n = 1879, RR 1.04 CI 0.91 to 1.17, very low quality evidence). For mental state outcome of 'no effect' of the study drug, there was again no significant difference between groups (4 RCTs, n = 383, RR 1.24 CI 0.61 to 2.52, very low quality evidence). Death was not reported in any of the included studies. There was no significant difference in rates of dystonia with perphenazine versus any other antipsychotic drugs (4 RCTs, n = 416, RR 1.36 CI 0.23 to 8.16, very low quality evidence), nor was there a significant difference between groups for serious adverse events (2 RCTs, n = 1760, RR 0.98 CI 0.68 to 1.41, very low quality evidence).

AUTHORS' CONCLUSIONS

Although perphenazine has been used in randomised trials for more than 50 years, incomplete reporting and the variety of comparators used make it impossible to draw clear conclusions. All data for the main outcomes in this review were of very low quality evidence. At best we can say that perphenazine showed similar effects and adverse events as several of the other antipsychotic drugs. Since perphenazine is a relatively inexpensive and frequently used compound, further trials are justified to clarify the properties of this classical antipsychotic drug.

Antidepressants for the negative symptoms of schizophrenia

BACKGROUND

Negative symptoms are common in people with schizophrenia and are often difficult to treat with antipsychotic drugs. Treatment often involves the use of various add-on medications such as antidepressants.

OBJECTIVES

To review the effects of the combination of antipsychotic and antidepressant drug treatment for management of negative symptoms in schizophrenia and schizophrenia-like psychoses.

SEARCH STRATEGY

We searched the Cochrane Schizophrenia Group's register (January 2004). We also contacted authors of included studies in order to identify further trials.

SELECTION CRITERIA

We included all randomised controlled trials comparing antipsychotic and antidepressant combinations with antipsychotics alone for the treatment of prominent negative symptoms in schizophrenia and/or schizophrenia-like psychoses.

DATA COLLECTION AND ANALYSIS

Working independently, we selected and critically appraised studies, extracted data and analysed on an intention-to-treat basis. Where possible and appropriate we calculated the relative risk RR) and their 95% confidence intervals (CI), with the number needed to treat (NNT).

MAIN RESULTS

We included five studies (all short-term, total N=190). We found no significant difference for 'leaving the study early for any reason' between the antipsychotic plus antidepressant combination and the control group (n=90, 3 RCTs, RR 3.0 CI 0.35 to 26.04). Leaving early due to adverse events (n=64, 2 RCTs, RR 5.0 CI 0.26 to 97.0) and leaving the study early due to inefficacy (n=34, 1 RCT, RR 3.0 CI 0.13 to 68.84) also showed no significant difference between the two treatment groups. In terms of clinical response, participants treated with the antipsychotic plus antidepressant medications showed a statistically significant greater improvement (n=30, 1 RCT, WMD -1.0 CI -1.61 to -0.39) and showed a significantly lower severity at endpoint (n=30, 1 RCT, WMD -0.9 CI -1.55 to -0.25) on the Clinical Global Impression Scale than those treated with antipsychotics alone. More people allocated to combination therapy had a clinically significant improvement in negative symptoms compared with those given antipsychotics and placebo (n=60, 2 RCTs, RR 0.56 CI 0.32 to 0.97, NNT 3 CI 3 to 34). Significant differences in favour of the combination therapy were seen in different aspects of negative symptoms: 'affective flattening' (n=30, 1 RCT, WMD -7.0 CI -10.37 to -3.63), 'alogia' (n=26, 1 RCT, WMD -3.00 CI -5.14 to -0.86) and 'avolition' (n=30, 1 RCT, WMD -3.0 CI -5.04 to -0.96). No statistically significant difference was found between treatment groups in regards to the outcome 'at least one adverse event' (n=84, 2 RCTs, RR 1.80 CI 0.66 to 4.90). For movement disorders and other adverse effects, no statistically significant differences were found in any of the studies that provided usable data on these outcomes. There are no data at all on outcomes such as compliance, cost, social and cognitive functioning, relapse, recurrence of negative symptoms, rehospitalisation or quality of life. There are no medium or long term data.

AUTHORS' CONCLUSIONS

The combination of antipsychotics and antidepressants may be effective in treating negative symptoms of schizophrenia, but the amount of information is currently too limited to allow any firm conclusions. Large, pragmatic, well-designed and reported long term trials are justified.

Inhibitory effects of psychotropic drugs on mexiletine metabolism in human liver microsomes: prediction of in vivo drug interactions

Mexiletine, an anti-arrhythmic agent, is used for the control of ventricular arrhythmias and for neuropathic pain from cancer or diabetes mellitus. It is sometimes used together with psychotropic drugs in patients with depression, schizophrenia or sleep disorder. It is metabolized mainly by cytochrome P450 (CYP) 2 D 6 and, to a minor extent, by CYP1A2. To predict possible drug interactions between mexiletine and psychotropic drugs, the inhibitory effects of 14 psychotropic drugs (phenytoin, carbamazepine, fluvoxamine, paroxetine, fluoxetine, citalopram, sertraline, imipramine, desipramine, haloperidol, thioridazine, olanzapine, etizolam, and quazepam) on mexiletine metabolism in human liver microsomes were determined. Fluoxetine (Ki=0.6+/- 0.1 microM), sertraline (Ki=7.6+/- 0.8 microM) and desipramine (Ki=3.2+/- 0.5 microM) competitively inhibited the mexiletine p-hydroxylation in human liver microsomes. Thioridazine (Kis=0.5+/- 0.2 microM; Kii =3.6+/-1.6 microM) and paroxetine (Kis=1.7+/- 0.7 microM; Kii=3.6+/- 0.9 microM) exhibited a mixed-type inhibition (competitive and non-competitive) toward mexiletine p-hydroxylation in human liver microsomes. The changes of the in vivo clearance of mexiletine by the psychotropic drugs were predicted by 1+(I/Ki) using the in vitro Ki and unbound inhibitor concentrations in liver. The values were calculated as 2.4 for paroxetine, 5.5 for fluoxetine, 1.1 for sertraline, 2.8 for desipramine and 2.2 for thioridazine. In addition, paroxetine exhibited a mechanism-based inactivation with Ki=0.7 microM and Kinact=0.15 min(-1). The present study predicted the possibility of drug interactions between mexiletine and paroxetine, fluoxetine, desipramine, and thioridazine in clinical use.

Perphenazine for schizophrenia

BACKGROUND

Perphenazine is an old phenothiazine antipsychotic with a potency similar to haloperidol. It has been used for many years and is popular in the northern European countries and Japan.

OBJECTIVES

To examine the clinical effects and safety of perphenazine for those with schizophrenia and schizophrenia-like psychoses.

SEARCH STRATEGY

We searched the Cochrane Schizophrenia Group's register (June 2001), references of all included studies and contacted pharmaceutical companies and authors of included studies in order to identify further trials.

SELECTION CRITERIA

We included all randomised controlled trials that compared perphenazine with other treatments for people with schizophrenia and/or schizophrenia-like psychoses. We excluded trials of depot formulations of perphenazine.

DATA COLLECTION AND ANALYSIS

Two reviewers independently inspected citations and, where possible, abstracts. We ordered papers, inspected and quality assessed them. We extracted data, again working independently. If loss to follow up was greater than 50% we considered results as 'prone to bias'. For dichotomous data we calculated the relative risk (RR), the 95% confidence interval (CI) and, where appropriate, the number needed to treat/harm (NNT/H) on an intention-to-treat basis. For continuous data, we calculated weighted mean differences (WMD).

MAIN RESULTS

The review currently includes 25 studies with 2478 patients, 2285 of whom had been randomised to interventions that were relevant for the review such as perphenazine, other antipsychotic drugs or placebo. The trials were carried out between 1961 and 1993. All but one trial were short term with a duration of between ten days and 12 weeks. Descriptions of allocation and blinding were usually incomplete. Six studies (n=300) compared perphenazine with placebo. Perphenazine was associated with fewer participants leaving the trials early due to relapse or worsening of symptoms (n=84, RR 0.1 CI 0.03 - 0.4, NNT 2 CI 1 to 20). Twenty studies compared perphenazine (n=738) with other antipsychotics (n=1278). Perphenazine seemed as effective as other antipsychotics ('global state unimproved or worse' n=1327, RR 1.0 CI 0.9 to 1.2). We found no clear differences in terms of specific aspects of efficacy, behaviour or tolerability. However, interpretation of findings of the review was limited by poor reporting and the use of 24 different comparator antipsychotics in the 20 trials.

AUTHORS' CONCLUSIONS

Although perphenazine has been randomised for more than 40 years, incomplete reporting and the variety of comparators used make it impossible to draw clear conclusions. At best we can say that perphenazine showed similar effects and adverse events as several of the other pooled antipsychotic drugs. Since perphenazine is a relatively inexpensive and frequently used compound, further trials are justified to clarify the properties of this classical antipsychotic drug.

Pharmacokinetic Factors in the Adverse Cardiovascular Effects of Antipsychotic Drugs

Antipsychotics may cause serious adverse cardiovascular effects, including prolonged QT interval and sudden death. This review considers antipsychotic-induced cardiovascular events from three perspectives: high-risk drugs, high-risk individuals and high-risk drug interactions. Pharmacokinetic drug interactions involving the cytochrome P450 (CYP) enzymatic pathway and pharmacodynamic interactions leading to direct cardiotoxic effects are discussed. Original reports on antipsychotic-induced drug interactions are reviewed, with consideration of management guidelines. The literature was reviewed from 1 January 1966 to 1 February 2002. The literature search revealed only 12 original articles published on antipsychotic drug interactions leading to cardiovascular adverse events. Only 4 of the 12 reports were prospective studies; the remainder were either retrospective or anecdotal.Although poor study designs preclude a definitive statement, it appears that pharmacokinetic interactions primarily involved the CYP2D6 and CYP3A4 enzymatic pathways. Those involving the CYP2D6 isozyme included interactions with tricyclic antidepressants, selective serotonergic reuptake inhibitors and beta-blockers. Among these drug interactions, tricyclic antidepressants were most likely to reach clinical significance because of their limited therapeutic index. Drug interactions related to the CYP3A4 pathway were generally less severe, and involved high-potency antipsychotics coadministered with inhibitors such as clarithromycin. Strategies are discussed for the management of adverse cardiovascular events related to antipsychotic drug interactions, including the use of an algorithm. Large, randomised, placebo-controlled studies with strict inclusion criteria are needed to determine the role that antipsychotics play in QT prolongation and sudden death.

Clinically significant pharmacokinetic drug interactions with psychoactive drugs: antidepressants and antipsychotics and the cytochrome P450 system

Psychotherapeutic drugs (antipsychotics and antidepressants) are widely used for treating anxiety. Many psychotherapeutic drugs are metabolized mainly by cytochrome P450 (CYP)2C19 and CYP2D6, and are often administered with other drugs. Therefore, it is necessary to be careful when co-administering psychotherapeutic drugs whose metabolism might be inhibited by other drugs. In particular, selective serotonin reuptake inhibitors (SSRIs) inhibit the metabolism of psychotherapeutic drugs mediated by CYP2C19 and CYP2D6. It is useful to phenotype CYP2C19 and CYP2D6 (extensive metabolizers or poor metabolizers) before giving such medication. Knowledge of substrates, inhibitors and inducers of CYP isoenzymes may help clinicians to anticipate and avoid psychotherapeutic drug interactions and improve rational prescribing practices. In addition, genotyping for these drugs may be also useful in preventing side-effects.

Influence of neuroleptics on the metabolism of tricyclic antidepressants--in vitro experiments with rat liver microsomes

The influence of two neuroleptics--the phenothiazine perazine and the butyrophenone haloperidol--on the metabolism of the tricyclic antidepressants amitriptyline (AMI), imipramine (IMI), and chlorimipramine (CMI) was studied in vitro in isolated liver microsomes of female Sprague-Dawley rats. The rats were pretreated over 10 days with either NaCl solutions or with 1, 3, and 10 mg/kg haloperidol or 5 and 15 mg/kg perazine, respectively. The microsomal fraction was incubated with various concentrations of antidepressants. The drugs and their metabolites were analyzed by high-performance liquid chromatography (HPLC). Neither pretreatment with haloperidol nor perazine had any significant influence on the demethylation and N-oxidation activity of the microsomes. Benzylic 10-hydroxylation of AMI or IMI or 10- and 11-hydroxylation of CMI was inhibited significantly by pretreatment with perazine, as was 2-hydroxylation of IMI and CMI, whereas 8-hydroxylation of CMI was not influenced. The inhibition was dose dependent. With haloperidol, only the high dose of 10 mg/kg caused a significant inhibition of benzylic 10-hydroxylation, whereas phenolic hydroxylation was not influenced. The inhibition was much lower than for perazine. Comparing the results with pharmacokinetic studies in humans revealed a good agreement in metabolic pathways. The study could therefore be important in the choice of neuroleptic drugs in combination therapy.