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Aravagiri M, Marder SR. Simultaneous determination of risperidone and 9-hydroxyrisperidone in plasma by liquid chromatography/electrospray tandem mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2000; 35:718-724. [PMID: 10862124 DOI: 10.1002/1096-9888(200006)35:6<718::aid-jms999>3.0.co;2-o] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A simple and highly sensitive liquid chromatographic/electrospray tandem mass spectrometric (LC/MS/MS) assay was developed for the simultaneous determination of risperidone (RSP) and its major circulating metabolite 9-hydroxyrisperidone (9-OH-RSP) in the plasma of humans and rats. A simple one-step solvent extraction with 15% methylene chloride in pentane was used to isolate the compounds from plasma. The compounds were eluted from a phenyl-hexyl column and detected with a Perkin-Elmer SCIEX API2000 triple-quadrupole mass spectrometer using positive ion atmospheric pressure electrospray ionization and multiple reaction monitoring. The assay was linear over the range 0.1-100 ng ml(-1) when 0.5 ml of plasma was used in the extraction. The overall intra- (within-day) and inter- (between days) assay variations were < 11%. The variations in the concentrations of two long-term quality control samples from pooled patient plasma samples analyzed over a period of 6 months were approximately 10%. The analysis time for each sample was 4 min and more than 100 samples could be analyzed in one day by running the system overnight. The assay is simple, highly sensitive, selective, precise and fast. This method is being used for the therapeutic drug monitoring of schizophrenic patients treated with RSP and to study the pharmacokinetics and tissue distribution of RSP and 9-OH-RSP in rats.
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152
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Bhana N, Spencer CM. Risperidone: a review of its use in the management of the behavioural and psychological symptoms of dementia. Drugs Aging 2000; 16:451-71. [PMID: 10939309 DOI: 10.2165/00002512-200016060-00005] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
UNLABELLED Risperidone is a benzisoxazole derivative which has proven efficacy against the positive and negative symptoms of schizophrenia. It has more recently been investigated and shown efficacy as a treatment for the behavioural and psychological symptoms associated with dementia in the elderly. Risperidone has pharmacological properties resembling those of the atypical antipsychotic clozapine and an improved tolerability profile compared with the conventional antipsychotic haloperidol. Risperidone has antagonistic activity primarily at serotonin 5-HT2A and dopamine D2 receptors. In the first 2 large, well controlled trials of an antipsychotic agent used in the treatment of elderly patients with Alzheimer's dementia, vascular dementia or mixed dementia, risperidone 1 mg/day was at least as effective as haloperidol and superior to placebo, as assessed by the rating scales for global behaviour, aggression and psychosis. In extension phases of the 2 trials, clinical benefits were maintained for treatment periods of up to 1 year, with an incidence rate of tardive dyskinesia (2.6%) one-tenth of that seen with conventional antipsychotics. Risperidone, administered at a low dosage of 1 mg/day was associated with fewer extrapyramidal symptoms compared with haloperidol in elderly patients. Risperidone was well tolerated with no clinically relevant abnormalities in laboratory tests, vital signs or electrocardiogram results. CONCLUSION The efficacy of risperidone has been demonstrated in the treatment of the behavioural and psychological symptoms associated with dementia in the elderly. Preliminary results from 1-year extension studies confirm the favourable efficacy and tolerability profile of risperidone 1 mg/day. Although head to head studies with other atypical antipsychotic agents are required and the long term use of the drug requires clarification, risperidone represents a generally well tolerated and effective treatment in the management of dementia-associated behavioural and psychological symptoms in the elderly.
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153
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Yoshimura R, Nakamura J, Ueda N, Terao T. Effect of risperidone on plasma free 3-methoxy-4-hydroxyphenylglycol (pMHPG) levels in schizophrenic patients: relationship among plasma concentrations of risperidone and 9-hydroxyrisperidone, pMHPG levels, and clinical improvement. Int Clin Psychopharmacol 2000; 15:175-80. [PMID: 10870876 DOI: 10.1097/00004850-200015030-00007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We examined the relationships among the clinical efficacies of risperidone, plasma concentrations of risperidone and its active metabolite, 9-hydroxyrisperidone, and changes in plasma free MHPG (pMHPG) in 14 schizophrenic patients. Clinical improvement in negative symptoms of schizophrenia treated with risperidone has been associated with increased pMHPG and, in the present study, there were positive correlations between plasma 9-hydroxyrisperidone concentrations and increased pMHPG levels. These results suggest that risperidone might improve negative symptoms in schizophrenia by influencing noradrenergic neurons.
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Hill RC, McIvor RJ, Wojnar-Horton RE, Hackett LP, Ilett KF. Risperidone distribution and excretion into human milk: case report and estimated infant exposure during breast-feeding. J Clin Psychopharmacol 2000; 20:285-6. [PMID: 10770482 DOI: 10.1097/00004714-200004000-00036] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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155
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Prakash C, Kamel A, Cui D, Whalen RD, Miceli JJ, Tweedie D. Identification of the major human liver cytochrome P450 isoform(s) responsible for the formation of the primary metabolites of ziprasidone and prediction of possible drug interactions. Br J Clin Pharmacol 2000; 49 Suppl 1:35S-42S. [PMID: 10771452 PMCID: PMC2015052 DOI: 10.1046/j.1365-2125.2000.00151.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AIMS To identify the cytochrome P450 (CYP) isoform(s) responsible for the formation of the primary metabolite of ziprasidone (ziprasidone sulphoxide), to determine the kinetics of its formation and to predict possible drug interactions by investigating CYP isoform inhibition in an in vitro study. METHODS In vitro metabolism of [14C]-ziprasidone was studied using human liver microsomes. The metabolites were identified using mass spectrometry. The kinetics of metabolite formation were determined using [14C]-ziprasidone (10-200 microM) over 5 min, and Km and Vmax were estimated from Lineweaver-Burk plots. IC50 values for the inhibition of specific probe substrates for CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4, by ziprasidone, risperidone and 9-hydroxyrisperidone were also determined using human liver microsomes from three subjects. Mean Ki values were calculated. RESULTS Three CYP-mediated metabolites - ziprasidone sulphoxide, ziprasidone sulphone and oxindole acetic acid - were identified. The apparent Km and Vmax values for the formation of the major metabolite, ziprasidone sulphoxide (measured as the sum of sulphoxide and sulphone) were 235 microM and 1.14 nmol mg(-1) protein min(-1), respectively. Isoform-selective inhibitors and recombinant enzymes indicated that CYP3A4 is responsible for the formation of ziprasidone metabolites. Ziprasidone was not a substrate for the other isoforms studied. Similar in vitro inhibition of CYP2D6 (Ki 6.9-16 microM) and CYP3A4 (Ki 64-80 microM) was obtained with ziprasidone, risperidone and 9-hydroxyrisperidone. The in vivo free drug concentrations associated with clinically effective doses of ziprasidone are at least 1500-fold lower than the mean Ki for either CYP2D6 inhibition or CYP3A4 inhibition. CONCLUSIONS Ziprasidone is predominantly metabolized by CYP3A4 in human liver microsomes and is not expected to mediate drug interactions with coadministered CYP substrates, at clinically effective doses.
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Alfaro CL, Nicolson R, Lenane M, Rapoport JL. Carbamazepine and/or fluvoxamine drug interaction with risperidone in a patient on multiple psychotropic medications. Ann Pharmacother 2000; 34:122-3. [PMID: 10669197 DOI: 10.1345/aph.19223] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Iakovlev VA. [The new antipsychotic preparation Rispolept (risperidone)]. VOENNO-MEDITSINSKII ZHURNAL 1999; 320:43-5. [PMID: 10650767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
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158
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Bork JA, Rogers T, Wedlund PJ, de Leon J. A pilot study on risperidone metabolism: the role of cytochromes P450 2D6 and 3A. J Clin Psychiatry 1999; 60:469-76. [PMID: 10453802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
BACKGROUND The limited available information on plasma risperidone levels shows a stable relationship between daily doses of risperidone and total plasma concentration (risperidone plus its active metabolite 9-hydroxyrisperidone). The ratio between risperidone and 9-hydroxyrisperidone characterizes cytochrome P450 2D6 (CYP2D6) status. According to the manufacturer, the CYP2D6 genotype or drugs that influence CYP2D6 or other cytochrome P450 isoenzyme activity are not expected to be clinically significant. One case report suggests that CYP3A participates in the metabolism of risperidone. METHOD A case series of 13 risperidone patients (the initial case and 12 new cases) who were genotyped for CYP2D6 were followed, and another 20 risperidone patients from a case-control study for the CYP2D6 genotype were reviewed. RESULTS The CYP2D6 poor metabolizers, who are enzyme deficient (2/13 in the case series and 3/20 in the case-control study), did not appear to tolerate risperidone well. Drugs affecting CYP3A, in particular powerful inducers and inhibitors, resulted in at least a 2-fold decrease or increase in plasma risperidone levels. CONCLUSION The anecdotal nature of this study is clearly a limitation. Drugs influencing CYP3A and CYP2D6 metabolic activity may significantly affect risperidone levels. Thus, plasma level monitoring of risperidone in a clinical setting may be useful, especially if patients are taking multiple medications or a CYP2D6 deficiency is suspected. New prospective studies under more controlled conditions are needed to verify these hypotheses.
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Lee DY, Lee KU, Kwon JS, Jang IJ, Cho MJ, Shin SG, Woo JI. Pharmacokinetic-pharmacodynamic modeling of risperidone effects on electroencephalography in healthy volunteers. Psychopharmacology (Berl) 1999; 144:272-8. [PMID: 10435394 DOI: 10.1007/s002130051003] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
RATIONALE CNS-active drugs produce specific electroencephalographic changes and the concentration-effect relationship of antipsychotics may be elucidated by adopting electroencephalography (EEG) as an effect measurement tool. OBJECTIVE The purpose of the present study was to determine the concentration-effect relationship of risperidone by assessing the EEG effect after oral administrations of single dose risperidone in healthy young males. METHODS Nine healthy male volunteers received a 1 mg single oral dose of risperidone according to a placebo controlled crossover design. Plasma levels of risperidone and its active metabolite 9-hydroxyrisperidone were measured by radioimmunoassay. Quantitative EEG parameters were obtained for each of four frequency bands through spectral EEG analysis. The difference in the absolute power in the delta frequency band for the F3 lead between risperidone and placebo was used as a drug effect parameter. For pharmacokinetic-pharmacodynamic modeling, the hypothetical effect compartment kinetically linked to plasma by a first-order process was postulated. All curve fittings were done with the non-linear curve-fitting program NONLIN. RESULTS Our results showed that absolute powers in delta and theta frequency bands were higher for risperidone administration than for placebo at all EEG leads, and the maximum effects were detected at about 3 h after administration of the drug. The hysteresis loop was observed in the plot of plasma concentration of risperidone or sum of risperidone and 9-hydroxyrisperidone (Cp) versus EEG effect for each subject. A linear model adequately described the relationship between the effect compartment concentrations (Ce) and EEG effects, and the two limbs of hysteresis in the Cp-effect plot were collapsed in the Ce-effect plot for risperidone or risperidone plus 9-hydroxyrisperidone. CONCLUSION The increases of absolute power for delta and theta frequency bands of EEG were induced by single oral administration of risperidone. The linear PK-PD model fit well with the relationship between effect compartment concentrations (Ce) and EEG effects of risperidone.
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Amchin J, Zarycranski W, Taylor KP, Albano D, Klockowski PM. Effect of venlafaxine on the pharmacokinetics of risperidone. J Clin Pharmacol 1999; 39:297-309. [PMID: 10073330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
An open-label study evaluated the effect of steady-state venlafaxine on the single-dose pharmacokinetic profile of risperidone, a CYP2D6 substrate; its active metabolite, 9-hydroxyrisperidone; and the total active moiety (risperidone plus 9-hydroxyrisperidone). Thirty healthy subjects received a 1 mg oral dose of risperidone before and after venlafaxine dosing to steady state. No significant changes occurred between treatments in the area under the concentration-time curve (AUC) for 9-hydroxyrisperidone or the total active moiety. However, venlafaxine weakly altered the pharmacokinetics of risperidone. Oral clearance decreased 38%, and the volume of distribution decreased 17%, resulting in a 32% increase in the AUC for risperidone. Renal clearance of 9-hydroxyrisperidone also decreased by 20% in the presence of venlafaxine. Safety profiles of both drugs were not altered. This study demonstrated that venlafaxine did not affect the pharmacokinetic profile of 9-hydroxyrisperidone or the total active moiety, although it weakly inhibited the metabolism of risperidone. These results show that venlafaxine is unlikely to be involved in a pharmacokinetic interaction with concomitant risperidone.
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Balant-Gorgia AE, Gex-Fabry M, Genet C, Balant LP. Therapeutic drug monitoring of risperidone using a new, rapid HPLC method: reappraisal of interindividual variability factors. Ther Drug Monit 1999; 21:105-15. [PMID: 10051063 DOI: 10.1097/00007691-199902000-00017] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Because of the enormous gap between premarketing studies in physically healthy subjects and clinical practice in patients, the present study reconsidered interindividual variability factors affecting risperidone concentrations under routine therapeutic drug monitoring conditions. The study included 92 patients, 27% of whom were 70 years or older. The patients received risperidone orally (dose range, 0.5-11 mg per day) and had concentrations of risperidone and the active metabolite 9-hydroxyrisperidone measured at steady state by a new, rapid, and sensitive method of high-performance liquid chromatography (HPLC). After normalization to a dose of 4 mg/day, median concentrations were 2.9 ng/ml (80% range, 0.9-27.9 ng/ml) for the parent compound and 24.1 ng/ml (80% range, 12.0-57.6 ng/ml) for the metabolite. When considering linear regression models, age was identified as a major source of interindividual variability, with expected increases of 340% and 220% for concentrations of parent compound and metabolite, with age increasing from 20 to 80 years. Body weight provided an additional significant contribution to the variability of 9-hydroxyrisperidone concentration, a 20-kg higher body weight associated with a concentration decrease of 23%. Serotonin-specific reuptake inhibitor (SSRI) comedication (fluoxetine, two patients; citalopram, two patients; paroxetine, one patient; fluvoxamine, one patient) was significantly associated with 4.6-fold higher concentrations of parent compound, in keeping with an inhibitory action on CYP2D6 enzyme. Significantly higher concentrations of 9-hydroxy-risperidone (+ 29%) were also observed in the 17 patients with biperiden comedication. Therapeutic drug monitoring data, collected in patients representative of the population for which the drug was intended, allowed us to quantify the dose reduction needed in elderly patients and thus provided valuable information in addition to the one collected during premarketing studies performed with strict inclusion and exclusion criteria.
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Aravagiri M, Yuwiler A, Marder SR. Distribution after repeated oral administration of different dose levels of risperidone and 9-hydroxy-risperidone in the brain and other tissues of rat. Psychopharmacology (Berl) 1998; 139:356-63. [PMID: 9809856 DOI: 10.1007/s002130050726] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Rats were treated with daily oral doses of 1, 4, and 6 mg/kg risperidone (RSP) and its metabolite, 9-hydroxy-risperidone (9-OH-RSP), for 15 consecutive days. Concentrations of RSP and 9-OH-RSP were measured in plasma, brain, liver, kidney, lungs and fat tissue by high-performance liquid chromatography with electrochemical detection. Non-specific distribution of RSP and 9-OH-RSP in various brain regions was also studied after administration of 6 mg/kg per day oral dose for 15 days. After RSP treatment, concentrations of 9-OH-RSP were higher than those of RSP in plasma and tissues except in brain, where both compounds were present in nearly equal concentrations. Similarly, after 9-OH-RSP treatment, levels of 9-OH-RSP were higher than levels of either RSP or 9-OH-RSP or the sum of RSP and 9-OH-RSP levels measured after treatment with RSP. There was a moderate relationship between RSP dose and tissue levels of RSP and 9-OH-RSP (all rs > or = 0.62, P < 0.01), except in fat. There was also a strong relationship between the dose and tissue levels of 9-OH-RSP (all rs > or = 0.68, P < 0.005). A significant relationship was found between plasma levels of RSP and brain levels of RSP and 9-OH-RSP (all rs > or = 0.57, P < 0.03) after treatment with RSP. After 9-OH-RSP treatment, a much stronger relationship was observed between plasma and brain 9-OH-RSP levels (rs > or = 0.90, P < 0.005). The plasma concentrations of RSP and 9-OH-RSP appear to reflect their concentrations in brain. The tissue-to-plasma ratios of RSP and 9-OH-RSP were relatively low compared to other antipsychotics. In liver, kidney and lung the tissue to plasma ratio for RSP and 9-OH-RSP after treating with RSP ranged from 0.85 to 3.4. The brain to plasma ratio for RSP and 9-OH-RSP was several-fold lower than that in peripheral tissues. After RSP administration, the mean brain to plasma level ratio for RSP was 0.22, and for 9-OH-RSP to it was 0.04. The brain to plasma ratio of 9-OH-RSP after giving 9-OH-RSP was similarly low (0.04). The low brain/plasma ratio of high potency RSP and 9-OH-RSP may in part be due to their low lipophilicity, log P = 3.04 and 2.32, respectively, resulting in limited non-specific accumulation in brain tissue.
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Remington G, Kapur S, Zipursky R. APA Practice Guideline for schizophrenia: risperidone equivalents. American Psychiatric Association. Am J Psychiatry 1998; 155:1301-2. [PMID: 9734565 DOI: 10.1176/ajp.155.9.1301a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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164
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Lane HY, Chang WH. Risperidone-carbamazepine interactions: is cytochrome P450 3A involved? J Clin Psychiatry 1998; 59:430-1. [PMID: 9721825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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165
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Lauterbach EC. Catatonia-like events after valproic acid with risperidone and sertraline. NEUROPSYCHIATRY, NEUROPSYCHOLOGY, AND BEHAVIORAL NEUROLOGY 1998; 11:157-63. [PMID: 9742515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A patient with schizoaffective disorder developed signs of catatonia while on a regimen of valproic acid, sertraline, and risperidone. The catatonic features evolved for the first time after a single dose of valproate and were alleviated by lorazepam. The same catatonic signs recurred after a second dose of valproate and again remitted after lorazepam. Catatonia did not recur subsequent to discontinuing valproate, and the patient had tolerated the combination of valproate and risperidone in the past without developing catatonia. Although the catatonia in this case initially appears to be paradoxical, the phenomenon is actually consistent with current models of catatonia. A unique drug interaction may account for this phenomenon. Possible pharmacokinetic and pharmacodynamic explanations are discussed, including the relation of catatonia to increased activity of the medial globus pallidus and current models of catatonia.
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Aravagiri M, Marder SR, Wirshing D, Wirshing WC. Plasma concentrations of risperidone and its 9-hydroxy metabolite and their relationship to dose in schizophrenic patients: simultaneous determination by a high performance liquid chromatography with electrochemical detection. PHARMACOPSYCHIATRY 1998; 31:102-9. [PMID: 9657237 DOI: 10.1055/s-2007-979308] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A simple, sensitive and accurate method for the simultaneous determination of risperidone (RSP) and its 9-hydroxy metabolite (9-OH-RSP) in human plasma is described. The relationship between dose of RSP and the plasma concentration of RSP and 9-OH-RSP in a clinical situation is discussed. Both compounds were isolated from plasma by a simple one-step liquid-liquid extraction with 15% methylene chloride in pentane. High-performance liquid chromatography separations were made on a cyano column and the compounds were detected by electrochemical detector. The method had sufficient sensitivity to determine RSP and 9-OH-RSP accurately at concentrations as low as 0.25 ng/ml when 1 ml of plasma is used for the analysis. The assay determinations were accurate, precise and consistent with a coefficient of variation less than 15%. Commonly co-administered drugs and other antipsychotics did not interfere with the analysis of either RSP or 9-OH-RSP There were large variations in inter- and intra-individual values of plasma concentrations of RSP and 9-OH-RSP. The 9-OH-RSP appears to be the major circulating active moiety and its plasma concentrations were, on the average 22 fold higher than that of RSP in schizophrenic patients treated with RSP. The ratio of RSP/9-OH-RSP concentrations suggested that three of the patients may have deficiency in cytochrome P450 enzyme CYP 2D6. The plasma concentrations of RSP showed a weak relationship with the administered daily oral dose (r = 0.4684, p = 0.01, n = 215). However, there was a good relationship between the daily dose of RSP and the plasma concentration of 9-OH-RSP (r = 0.6654, p = 0.01, n = 280) or the total active moiety, sum of RSP and 9-OH-RSP concentrations (r = 0.7041, p = 0.0005, n = 280). The measurement of the total active moiety in plasma of schizophrenic patients may be useful for assessing the relationship between dose and plasma concentration and dose and clinical outcome of patients rather than measuring RSP alone.
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Abstract
With a decade of neuroreceptor imaging of antipsychotics behind us, this article attempts to synthesise what has been learnt about the mechanism of action of antipsychotics using these techniques. The data show that: (i) the 'typical' antipsychotics bind mainly to the dopamine D2 receptor, and that 60-80% D2 occupancy may provide optimal antipsychotic response with little extrapyramidal side effects; (ii) all the clinically available 'atypical' antipsychotics show a higher occupancy of the 5-HT2 than D2 receptors; (iii) however, these 'atypical' antipsychotics differ in their D2 occupancy. The D2 occupancy of risperidone is within the typical range (i.e. > 60%) while that of clozapine is clearly lower (< 60%); (iv) antipsychotics with combined 5-HT2/D2 antagonism lose some of their 'atypical' properties if used in doses where their D2 occupancy is too high (> 80%). Based on these data a framework is suggested wherein antipsychotics may be classified on the basis of their D2 and 5-HT2 occupancy in patients at steady state while taking clinically relevant doses. Within this framework typical antipsychotics are classified as 'high-D2', resperidone as 'high-D2 high-5HT2' and clozapine as a 'low-D2 high-5HT2' antipsychotic. The justification, limitations and the value of this framework in understanding and investigating newer antipsychotics is discussed.
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169
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Zayas EM, Grossberg GT. The treatment of psychosis in late life. J Clin Psychiatry 1998; 59 Suppl 1:5-10; discussion 11-2. [PMID: 9448664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The authors emphasize the need for careful differential diagnosis when symptoms of psychosis arise in patients over the age of 65 years. Prevalence of psychotic disorders in the elderly ranges from 0.2%-4.7% in community-based samples to 10% in a nursing home population and as high as 63% in a study of Alzheimer's patients. Risk factors associated with the development of psychotic symptoms and common causes of delirium are reviewed. Because age-related changes affect the pharmacokinetics of neuroleptics, the authors' treatment recommendations, which include the use of traditional and novel antipsychotics, take into account the higher risk of side effects in the elderly.
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Su TP, Malhotra AK, Hadd K, Breier A, Pickar D. D2 dopamine receptor occupancy: a crossover comparison of risperidone with clozapine therapy in schizophrenic patients. ARCHIVES OF GENERAL PSYCHIATRY 1997; 54:972-3. [PMID: 9337781 DOI: 10.1001/archpsyc.1997.01830220102017] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Sommers DK, Snyman JR, van Wyk M, Blom MW, Huang ML, Levron JC. Lack of effect of amitriptyline on risperidone pharmacokinetics in schizophrenic patients. Int Clin Psychopharmacol 1997; 12:141-5. [PMID: 9248870 DOI: 10.1097/00004850-199705000-00004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The interaction between plasma concentrations of the tricyclic antidepressant amitriptyline and the metabolism of the new antipsychotic risperidone was studied in 12 patients with chronic schizophrenia. Each patient received 3 mg risperidone twice a day for 28 days. Amitriptyline was coadministered at doses of 50 mg/day on day 15 and 100 mg/day on days 16 to 21. Amitriptyline did not significantly affect the mean plasma concentrations or pharmacokinetics of risperidone in schizophrenic patients or influence the antipsychotic fraction (the total concentration of risperidone and 9-hydroxyrisperidone, its primary and biologically active metabolite). These results suggest that risperidone dose need not be adjusted when coadministered with amitriptyline at doses up to 100 mg/day in schizophrenic patients.
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Gutierrez R, Lee PI, Huang ML, Woestenborghs R. Risperidone: effects of formulations on oral bioavailability. Pharmacotherapy 1997; 17:599-605. [PMID: 9165565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The bioavailability of risperidone was evaluated in an open-label, randomized, two-way, crossover study comparing a 1-mg tablet with a 1-mg/ml oral solution. Both formulations were administered as a single 1-mg dose with a 10-day washout period between treatments. Of 26 healthy men who entered the study, 23 completed both treatment periods. Plasma concentrations of risperidone and the active moiety (risperidone plus its active metabolite, 9-hydroxyrisperidone) were determined by radioimmunoassays. For key pharmacokinetic values (Cmax, AUC), the 90% CIs on the relative bioequivalence of risperidone, 9-hydroxyrisperidone, and the active moiety were contained within the equivalence range of 80-120% (80-125% for log-transformed data). The results demonstrate that the 1-mg/ml oral solution and the 1-mg tablet are bioequivalent.
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Abstract
We report the response to risperidone in seven hospitalized, adult patients who presented psychotic symptoms etiologically related to a general medical condition. The conditions included brain surgery in two, and anticardiolipin syndrome, renal failure, epilepsy, lupus, and metastatic carcinoma in one each. Four patients had failed previous treatment with at least one typical antipsychotic agent. Response to risperidone was assessed by the Brief Psychiatric Rating Scale (BPRS). Serum was collected for measurement of steady-state trough risperidone and 9-hydroxyrisperidone concentrations at effective doses in three patients. Amelioration of psychotic symptoms was noted in all seven patients. Mean (+/- SD) BPRS scores were reduced significantly from baseline (63.0 +/- 15.1) to endpoint (27.0 +/- 3.5; p < 0.01). The mean effective daily dose of risperidone was 3.1 +/- .7 mg and time to response was 4.7 +/- 2.4 days. Risperidone was not present at detectable concentrations in the three patients studied. The mean steady-state trough serum concentration of 9-hydroxyrisperidone in the three patients assessed was 20.3 +/- 9.8 ng/ml. These preliminary findings, which suggest that risperidone is a safe and effective agent in patients with psychotic symptoms due to various medical conditions, need to be confirmed by randomized, antipsychotic comparison trials involving a larger number of patients.
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175
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Ansseau M. [Pharma-clinics. Drug of the month. Risperidone (Risperdal)]. REVUE MEDICALE DE LIEGE 1996; 51:665-667. [PMID: 8984564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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176
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Henderson DC, Goff DC. Risperidone as an adjunct to clozapine therapy in chronic schizophrenics. J Clin Psychiatry 1996; 57:395-7. [PMID: 9746446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Some treatment-resistant schizophrenic patients improve enough to remain out of the hospital but continue to have significant positive or negative symptoms. METHOD The goal of this study was to assess the safety and potential efficacy of risperidone as an adjunct for schizophrenic patients treated with clozapine. In an open 4-week trial involving 12 DSM-III-R-diagnosed patients, the addition of risperidone to clozapine was well tolerated and did not affect serum clozapine concentrations significantly. RESULTS Total Brief Psychiatric Rating Scale (BPRS) scores and subscales measuring positive symptoms, negative symptoms, and depressive symptoms were significantly reduced from baseline. Ten of 12 participants had a 20% or greater reduction in the total BPRS score. CONCLUSION In this open trial, the addition of risperidone to clozapine was well tolerated and produced significant reduction of symptoms, suggesting that this may be a useful clinical approach. Because this was an open trial, the improvement we observed must be replicated in a controlled trial.
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177
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Nyberg S, Nakashima Y, Nordström AL, Halldin C, Farde L. Positron emission tomography of in-vivo binding characteristics of atypical antipsychotic drugs. Review of D2 and 5-HT2 receptor occupancy studies and clinical response. Br J Psychiatry Suppl 1996:40-4. [PMID: 8733822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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178
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Abstract
The current literature describing the pharmacokinetics of the atypical antipsychotics clozapine and risperidone is reviewed, and discussion on the clinical significance of these data is presented. These drugs are well absorbed when taken orally but are poorly bioavailable because of presystemic elimination. They are highly cleared by hepatic metabolism involving specific P450 isozymes. Risperidone elimination produces a potent active metabolite. Neither of the drugs has received extensive study related to drug-drug interactions, but several are potentially important because a purported therapeutic plasma concentration range is proposed for clozapine and a possible curvilinear dose response relationship has been reported for risperidone. The current clinical pharmacokinetic database for these atypical antipsychotics suggests that much can be learned with additional study that would be of value in individualizing their dosage regimens.
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179
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DeVane CL. Drug interactions and antipsychotic therapy. Pharmacotherapy 1996; 16:15-20. [PMID: 8778682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Various combinations of drugs may be used to treat psychotic disorders, but pharmacodynamic and pharmacokinetic interactions can result in adverse effects. In most cases, interactions are of clinical significance only when drug therapy is initiated or discontinued, or when major changes in dosage are made. A number of patient-related variables also affect the clinical significance of a drug-drug interaction. To help predict the occurrence of interactions, and therefore minimize or prevent them, the clinician should be familiar with each agent's pharmacokinetics, the enzymes involved in its metabolism, and the expected pharmacologic effects. With this knowledge, the clinician may consider decreasing the dosage of previous therapy or reducing the dosage of a coadministered drug to prevent or minimize the potential of an adverse interaction.
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180
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Snoeck E, Van Peer A, Sack M, Horton M, Mannens G, Woestenborghs R, Meibach R, Heykants J. Influence of age, renal and liver impairment on the pharmacokinetics of risperidone in man. Psychopharmacology (Berl) 1995; 122:223-9. [PMID: 8748391 DOI: 10.1007/bf02246543] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The pharmacokinetics of the antipsychotic agent risperidone were investigated in healthy young and elderly subjects, cirrhotic patients and patients with moderate and severe renal insufficiency. In a comparative trial, a single oral 1-mg dose was administered to fasting subjects. Plasma and urine concentrations of the parent compound risperidone and the active moiety (i.e. risperidone plus 9-hydroxy-risperidone) were measured by radioimmunoassays. No or only small changes in plasma protein binding were observed in hepatic and renal disease, whereas the protein binding was not influenced by aging. The inter-individual variability in plasma concentrations of the active moiety was much less than the variability in plasma concentrations of risperidone. Three out of six subjects, behaving like poor metabolizers, were on medication (thiethylperazine, amitriptyline, metoprolol) that may inhibit risperidone metabolism by CYP2D6 (debrisoquine 4-hydroxylase). The pharmacokinetics of risperidone in elderly and cirrhotic patients were comparable to those in young subjects, whereas total oral clearance was reduced in renal disease patients. The elimination rate and clearance of 9-hydroxy-risperidone was reduced in elderly and renal disease patients because of a diminished creatinine clearance. The CL(oral) of the active moiety, which is primarily 9-hydroxy-risperidone, was reduced by about 30% in the elderly and by about 50% in renal disease patients. In addition, the t1/2 of the active moiety was prolonged (19 h in young subjects versus about 25 h in elderly and renal disease patients). Based upon the pharmacokinetics of the active moiety, a dose reduction and a cautious dose titration is advised in the elderly and in patients with renal disease. In cirrhotic patients, the single-dose pharmacokinetics were comparable to those in healthy young subjects.
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181
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Volavka J. Lead-in placebo washout period. Br J Psychiatry 1995; 167:694. [PMID: 8564334 DOI: 10.1192/bjp.167.5.694a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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