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At least 19 recordsLinked to original sources
PubMed2000

Pimozide for schizophrenia or related psychoses.

BACKGROUND: Pimozide was first formulated in the late 1960s and marketed for the care of those with schizophrenia or related psychoses such as delusional disorder. OBJECTIVES: To assess the effects of pimozide for people with schizophrenia, non-affective psychotic mental illness and delusional disorder in terms of clinical, social and economic outcomes. SEARCH STRATEGY: Electronic searches of Biological Abstracts (1982-1995), The Cochrane Schizophrenia Group's Register, EMBASE (1980-1995), Janssen-Cilag UK's register of studies (1999), MEDLINE (1966-1995), PsycLIT (1974-1995), hand-searching the references of all included studies and contacting the manufacturers of the compound. SELECTION CRITERIA: All randomised trials relating to people with schizophrenia, or similar disorders comparing pimozide to other drug treatments were sought. Studies where randomisation was implied rather than stated were included if they did not change the results. Primary outcomes were clinically significant change in global function, mental state, relapse, hospital admission, death, adverse events and acceptability of treatment. DATA COLLECTION AND ANALYSIS: Studies were selected, rated and data extracted. For dichotomous data Relative Risks (RR) based on a random effects model with the 95% confidence intervals (CI) were estimated. The number needed to treat statistic (NNT) was calculated where indicated. Analysis was by intention-to-treat. MAIN RESULTS: This review currently includes 34 studies focusing on those with schizophrenia, none on people with delusional disorder. Few people have been randomised to pimozide versus placebo, but data from three longer term studies does suggest that the active drug prevents relapse (RR 0.59 CI 0.4-0.8, NNT 4 CI 2-13). Pimozide has similar efficacy to that of typical antipsychotic drugs for the outcomes of change in global functioning, mental state, relapse and leaving the study early. People allocated to pimozide did not have a higher mortality than those taking other antipsychotics. Pimozide was more likely to cause parkinsonian tremor (RR 1.6 CI 1.1-2.3, NNH 6 CI 3-44) and lead to a requirement for antiparkinsonian medication more frequently (RR 1.8, CI 1.2-2.6, NNH 3 CI 2-5) than other drugs. It was, however, less likely to cause sedation (RR 0.38 CI 0.2-0.7, NNH 6 CI 4-16). REVIEWER'S CONCLUSIONS: Although there are shortcomings in the data there is enough overall consistency, over different outcomes and time scales, to confirm that pimozide is a drug with similar efficacy to other more commonly used antipsychotics such as chlorpromazine for those with schizophrenia. There are no data to support or refute its use for those with delusional disorder.

Antipsychotic Agents↗
PubMed1982

Prediction of early relapse after pimozide discontinuation by response to d-amphetamine during pimozide treatment.

Thirteen schizophrenic patients underwent a d-amphetamine infusion while being treated with pimozide, an antipsychotic agent and a relatively specific dopamine (DA) blocker. Six patients who showed an acute increase in psychosis with d-amphetamine relapsed within 3 months after pimozide withdrawal. Of the seven patients who did not change in psychosis with d-amphetamine, six did not relapse after pimozide discontinuation (Fisher's exact test, p less than 0.005). Retrospectively, the psychosis-inducing effects of d-amphetamine were found to be predictive of psychotic exacerbation following subsequent pimozide withdrawal. Pimozide failed to block the psychotogenic effects of d-amphetamine in six patients indicating that other mechanisms besides DA may play a role in psychotic decompensation. The d-amphetamine infusion paradigm should be studied further to determine its clinical value for identifying which schizophrenic patients are at risk for relapse after discontinuation of neuroleptic treatment.

Acute Disease↗
PubMed1999

Effect of clarithromycin on the pharmacokinetics and pharmacodynamics of pimozide in healthy poor and extensive metabolizers of cytochrome P450 2D6 (CYP2D6).

BACKGROUND: The use of pimozide is associated with prolongation of the QT interval and fatal ventricular arrhythmia. We recently reported 2 fatal cases in patients taking pimozide and clarithromycin and we have shown that clarithromycin inhibits CYP3A-mediated metabolism of pimozide in vitro. In this study, we examined the effect of clarithromycin on pimozide pharmacokinetics and QT interval changes in a total of 12 healthy subjects (7 men and 5 women), documented as extensive metabolizers or poor metabolizers of CYP2D6. METHODS: In a randomized, double-blind placebo-controlled crossover design, subjects were given a single 6-mg oral dose of pimozide after 5 days of treatment with clarithromycin (500 mg twice a day) or a placebo pill. Blood samples were obtained before and for 96 hours after pimozide administration, and plasma pimozide and clarithromycin concentrations were measured by HPLC. Electrocardiograms for the analysis of the QTc intervals were recorded immediately before each blood sample. RESULTS: Pimozide significantly lengthened QTc interval in the first 20 hours in both the placebo-treated groups (delta QTcmax = 13.3 +/- 5.3 ms; P = .003) and clarithromycin-treated groups (delta QTcmax = 15.7 +/- 9.5 ms; P = .005) compared with baseline values. This is consistent with an effect of the parent drug. Clarithromycin caused a significant increase in the peak plasma concentration (P = .015), terminal elimination half-life (P = .003), and area under the plasma concentration-time curve (P = .024) and a decrease in the clearance (P = .029) of pimozide. Mean QTcmax observed within 20 hours of pimozide administration was significantly greater in the clarithromycin-treated group (23.8 +/- 12.2 ms; P = .0397) than in the placebo-treated group (16.8 +/- 6 ms). There was no significant effect of CYP2D6 or gender on the pharmacokinetics or pharmacodynamics of pimozide. CONCLUSIONS: A single 6-mg oral dose of pimozide resulted in measurable QT interval changes. Clarithromycin inhibited CYP3A-mediated pimozide metabolism and the resulting elevation in plasma concentrations may increase the risk of pimozide cardiotoxicity.

Adult↗
PubMed2005

Coadministration of sertraline with cisapride or pimozide: an open-label, nonrandomized examination of pharmacokinetics and corrected QT intervals in healthy adult volunteers.

BACKGROUND: Sertraline hydrochloride is a selective serotonin reuptake inhibitor with demonstrated efficacy and safety for the treatment of the following disorders: major depressive, obsessive-compulsive, panic, premenstrual dysphoric, social anxiety, and posttraumatic stress. Although sertraline is unlikely to cause clinically significant inhibition of cytochrome P450 (CYP) 3A4 substrates, even modest concentration increases for narrow therapeutic index drugs, such as pimozide or cisapride, are potentially important. OBJECTIVE: The goal of this study was to determine whether there is a pharmacokinetic interaction, as shown by plasma concentrations and electrocardiographic evidence of QTc intervals, between sertraline 200 mg QD and cisapride 10 mg QID, and between sertraline 200 mg QD and pimozide (single 2-mg dose). METHODS: Patients in group A were administered cisapride on days 1 and 2 (10 mg QID), day 3 (10 mg/d), days 25 through 29 (10 mg QID), and day 30 (10 mg/d). Sertraline was administered on days 4 through 29 at a starting dose of 50 mg/d, which was titrated upward in 50-mg increments every third day to a maximum of 200 mg/d. Patients in group B were treated with 2 mg of pimozide on days 1 and 39. Sertraline was administered on days 18 through 46 at a starting dose of 50 mg/d, which was titrated upward in 50-mg increments every third day to a maximum of 200 mg/d. RESULTS: There were 9 males and 6 females in group A (sertraline + cisapride) (mean age, 34.4 years for males, 41.7 years for females; mean weight, 78.7 kg for males, 66.6 kg for females; 14 Hispanic, 1 white), and 8 males and 7 females in group B (sertraline + pimozide) (mean age, 26.1 years for males, 33.4 years for females; mean weight, 70.8 kg for males, 61.4 kg for females; 15 Hispanic). Coadministration of sertraline and cisapride resulted in statistically significant reductions of 29% and 36% in cisapride C(max) and AUC from time 0 to 6 hours, respectively, compared with cisapride alone. Coadministration of sertraline and pimozide resulted in statistically significant increases of 35% and 37% in pimozide Cmax and AUC(0-infinity), respectively, compared with pimozide alone. No subject exhibited a prolongation of the QTc interval > or =15% with coadministration of sertraline and cisapride, or sertraline and pimozide. CONCLUSIONS: This study found that coadministration of sertraline with cisapride resulted in decreases in cisapride concentrations, and no significant effects on QTc intervals. Coadministration of sertraline 200 mg/d and a single dose of pimozide 2 mg produced significant increases in pimozide concentrations but no prolongation of the QTc interval > or =15%. This opposite effect for pimozide compared with cisapride, as well as other previously tested CYP3A4 substrates, suggests that there are mechanisms other than CYP3A4 involved in the sertraline-pimozide interaction.

Adult↗
PubMed1986

Effects of pimozide on appetitive behavior and locomotor activity: dissimilarity of effects when compared to extinction.

The effects of pimozide were examined in a runway paradigm using food reward. Rats received one of three doses of pimozide, vehicle or Ringer's prior to testing. Two additional groups received pimozide or vehicle after the test trial in the home cage. An extinction group received no food in the goal box on test days. Several components of running behavior were assessed as was food consumed in the goal box. Effects of pimozide on general locomotor activity were assessed in the open-field following the runway phase. Results of the runway indicated that pimozide-treated rats differed from the extinction group in latencies to leave the start box and enter the goal box. Pimozide-treated rats consumed less saccharin-flavored food than controls. The post-treatment pimozide group showed a reduction in saccharin-food intake suggesting a conditioned taste aversion. Thus, the reduction observed in the pretreated pimozide group may be due to some unconditioned aversion induced by the drug. Open-field revealed that pimozide resulted in lower activity than controls. This study indicates that the effects of pimozide on food reinforcement are not similar to the effects seen in extinction. These data are consistent with the hypothesis that the effects of pimozide, in this paradigm, constitute an interference with motor responses as opposed to an attenuation of reward properties of the stimuli.

Animals↗
PubMed1990

Inhibition of human breast cancer cell proliferation in tissue culture by the neuroleptic agents pimozide and thioridazine.

Permanent cell culture lines derived from human breast cancer tissue are important experimental models in the study of human breast cancer cell proliferation. In the present work, pimozide, thioridazine, W-13, and W-12 were shown to inhibit MCF-7 human breast cancer cell growth. The 50% inhibition concentration values determined in two proliferation assays, [3H]thymidine incorporation and cell number, were in close agreement for each compound tested. The order of potency for growth inhibition in the presence of 2% stripped calf serum was pimozide (Ki 2 microM) greater than thioridazine (Ki 5 microM) greater than W-13 (Ki 15 microM) greater than W-12 (Ki 39 microM). Similar concentrations of these compounds blocked estradiol-induced growth of MCF-7 cells, but estrogen receptor (ER) interactions do not seem to be involved. Pimozide and thioridazine had no effect on the estradiol binding properties of the MCF-7 ER, nor did pimozide interfere with the induction of progesterone receptors by estradiol. Furthermore, pimozide also inhibited incorporation of [3H]thymidine into MCF-7 cells stimulated by polypeptide hormones in serum-free medium. The Ki for pimozide in serum-free medium alone, 0.46 microM, was similar to that determined in the presence of insulin (0.42 microM), insulin-like growth factor I (0.54 microM), and epidermal growth factor (0.43 microM). The effects of pimozide on breast cancer cell growth were not limited to the MCF-7 cell line. Pimozide also blocked cell growth and [3H]thymidine incorporation into the ER-positive T47D and ZR75-1B human breast cancer cell lines and the ER-negative human breast cancer cell line, MDA-MB-231. Although numerous mechanisms of action of pimozide and thioridazine have been identified, both drugs are calmodulin antagonists at drug concentrations that inhibit breast cancer cell growth in vitro. Inhibition of MCF-7 cell growth by the selective calmodulin antagonists W-13 and W-12 is consistent with a role for calmodulin antagonism in the broad growth-inhibitory properties of pimozide. We conclude that pimozide and thioridazine may be useful in the control of estradiol- and polypeptide hormone-induced growth of ER-positive and ER-negative human breast tumors.

Antineoplastic Agents↗
PubMed1984

Pimozide attenuates free feeding: best scores analysis reveals a motivational deficit.

Pimozide treatment (1.0 and 2.0 mg/kg) decreased free feeding in rats. The animals were presented daily with 35 meal segments, each consisting of five 45-mg pellets; pimozide resulted in longer mean latencies to initiate eating, longer mean eating times per segment (duration scores) and more pellets left uneaten. The increase in durations was progressive both within and across test sessions; toward the end of the final session many pellets were left uneaten. Failure to initiate eating of the first pellet of each segment was rare, and was always preceded by failure to eat the fifth pellet of the preceding meal segment. To assess whether either the increase in latencies or the increase in durations reflected an impairment of absolute response capability, 'best scores' in the pimozide and control conditions were compared; the shortest latencies and durations in the pimozide condition were as 'good' as those of the control condition. However, the animals generally produced 'best' scores on fewer trials in the pimozide condition. An exception was on day 1 of testing, when the frequency of 'best' latencies was higher in the pimozide condition. The fact that the 'best' scores under pimozide equalled the 'best' scores under vehicle suggests that the pimozide-treated animals had the motoric capacity to respond normally. The facts that the pimozide-treated animals did not perform to the demonstrated limits of that capacity in a normal percentage of trials and that performance on days 2 and 3 of testing were 'worse' than performance on day 1 of testing suggest that pimozide causes a motivational deficit that has not been widely recognized.

Animals↗
PubMed1998

The cell death response to gamma-radiation in MCF-7 cells is enhanced by a neuroleptic drug, pimozide.

Neuroleptic drugs that bind sigma sites were tested for their ability to inhibit growth and radiosensitize MCF-7 human breast cancer cells. Inhibition of growth by approximately 50% occurred in cells exposed to pimozide (0.6 microM), haloperidol (10 microM), and the sigma ligand DTG (1,3-di(2-tolyl)guanidine, 20 microM), but no growth inhibition occurred in cells exposed to clozapine, a neuroleptic drug lacking sigma binding activity, or dextromethorphan, a selective sigma 1 binding ligand. Pimozide (2.5 microM), but not haloperidol (3.6 microM), enhanced the sensitivity of MCF-7 cells to gamma radiation in clonogenic survival assays. Pimozide significantly decreased MCF-7 clonogenic survival following a 5 or 8 Gy dose of gamma radiation, and the dose of radiation required for 1% survival (survival enhancement ratio, SER) was decreased by a factor of 2. Exposure of normal WI-38 human embryonic lung cells to pimozide did not increase their sensitivity to gamma radiation. Pimozide (2.5 microM) activated early apoptotic changes in MCF-7 cells that were detected by the uptake of Hoechst 33342 dye, and 10 microM pimozide activated a complete apoptotic pathway resulting in the death of > 90% of the cells within 24 hours. MCF-7 cells exposed to gamma radiation alone (8 Gy) showed giant cell formation, mitotic arrest, and a limited degree of apoptosis and necrosis. Within 50 hours of treatment with a combination of radiation and pimozide, cell numbers were sharply reduced compared with cultures exposed to either radiation or pimozide alone. We conclude that pimozide augmented the sensitivity of MCF-7 cells to radiation-induced cell killing through a mechanism not shared by haloperidol, but suggest that concentration of pimozide in MCF-7 cells as a result of an enrichment of sigma 2 sites might target the radiosensitization.

Antipsychotic Agents↗
PubMed1998

Identification and characterization of human cytochrome P450 isoforms interacting with pimozide.

Using human liver microsomes (HLMs) and recombinant human cytochrome P450 (CYP450) isoforms, we identified the major route of pimozide metabolism, the CYP450 isoforms involved, and documented the inhibitory effect of pimozide on CYP450 isoforms. Pimozide was predominantly N-dealkylated to 1,3-dihydro-1-(4-piperidinyl)-2H-benzimidazol-2-one (DHPBI). The formation rate of DHPBI showed biphasic kinetics in HLMs, which suggests the participation of at least two activities. These were characterized as high-affinity (K(m1) and Vmax1) and low-affinity (K(m2) and Vmax2) components. The ratio of Vmax1 (14 pmol/min/mg protein)/K(m1) (0.73 microM) was 5.2 times higher than the ratio of Vmax2 (244 pmol/min/mg protein)/K(m2) (34 microM). K(m2) was 91 times higher than K(m1). The formation rate of DHPBI from 25 microM pimozide in nine human livers correlated significantly with the catalytic activity of CYP3A (Spearman r = 0.79, P = .028), but not with other isoforms. Potent inhibition of DHPBI formation from 10 microM pimozide was observed with ketoconazole (88%), troleandomycin (79%), furafylline (48%) and a combination of furafylline and ketoconazole (96%). Recombinant human CYP3A4 catalyzed DHPBI formation from 10 microM pimozide at the highest rate (V = 2.2 +/- 0.89 pmol/min/pmol P450) followed by CYP1A2 (V = 0.23 +/- 0.08 pmol/min/pmol P450), but other isoforms tested did not. The K(m) values derived with recombinant CYP3A4 and CYP1A2 were 5.7 microM and 36.1 microM, respectively. Pimozide itself was a potent inhibitor of CYP2D6 in HLMs when preincubated for 15 min (Ki = 0.75 +/- 0.98 microM) and a moderate inhibitor of CYP3A (Ki = 76.7 +/- 34.5 microM), with no significant effect on other isoforms tested. Our results suggest that pimozide metabolism is catalyzed mainly by CYP3A, but CYP1A2 also contributes. Pimozide metabolism is likely to be subject to interindividual variability in CYP3A and CYP1A2 expression and to drug interactions involving these isoforms. Pimozide itself may inhibit the metabolism of drugs that are substrates of CYP2D6.

Antipsychotic Agents↗
PubMed1986

The effects of pimozide on drinking behavior in the rat: an investigation using the conditioned taste aversion paradigm.

In an attempt to examine the potential aversive properties of the neuroleptic pimozide, a conventional conditioned taste aversion (CTA) paradigm was employed. Rats were either pretreated with pimozide (1.0 mg/kg) before the presentation of a familiar or novel saccharin-flavored solution or tap water or received injections of pimozide after the presentation of a novel saccharin solution. Following this procedure, rats were given a two bottle choice test under drug-free conditions. All pretreated pimozide groups demonstrated a significant unconditioned reduction in fluid intake relative to the vehicle control group. These pimozide groups having different drinking histories did not differ from one another. Although pimozide did not induce a CTA in rats post-treated with this neuroleptic, overall this group drank significantly less saccharin than the control group. Furthermore, on the two bottle choice test, rats which received contingent exposure to pimozide and saccharin (pre and post conditions), did not demonstrate a preference for the saccharin solution. These results suggest that the reduction in fluid intake observed in the pretreated pimozide groups may be due to some unconditioned aversive state induced by the drug. These data indicate that the mechanisms involved in the reduction of fluid intake induced by pimozide may be unrelated to a manipulation of the reinforcing properties of the appetitive stimulus.

Analysis of Variance↗
PubMed1980

Pimozide: delayed onset of action at rat striatal pre- and postsynaptic dopamine receptors.

It has been reported that the antipsychotic drug, pimozide, is unique in that it blocks postsynaptic dopamine (DA) receptors, but not presynaptic DA receptors. This was examined by comparing pimozide with haloperidol for time of onset of action in several experimental paradigms designed to demonstrate blockade of pre- and postsynaptic striatal DA receptors. Haloperidol (1.0 mg/kg s.c.) caused near maximum catalepsy scores within 90 min after injection, a time when twice as much pimozide had yet to produce catalepsy. Pimozide consistently exhibited a delayed onset of action on several dopaminergic biochemical parameters including: increased striatal DA metabolism, increased DA receptors. In electrophysiological studies, pimozide did not block the ability of apomorphine to inhibit DA impulse flow if given 5 to 10 min before apomorphine, but was effective if longer pretreatment times were allowed. These data indicate that a delay or pimozide action occurs at both postsynaptic and presynaptic DA receptors. It is known that pimozide binds with high affinity to neuroleptic binding sites (in vitro) and rapidly enters the brain after systemic injection. Pretreatment of animals with SKF 525-A, an inhibitor of liver mixed-function oxidase enzymes, had little or no effect on pimoxide's actions, suggesting that formation of an active metabolite is not the cause of pimozide's delayed actions. The reason for the delayed action is unclear, but pimozide will interact with both pre- and postsynaptic DA receptors if given sufficient time.

Animals↗