Chronic treatment with asenapine affects cytochrome P450 2D (CYP2D) in rat brain and liver. Pharmacological aspects

Neuroleptics have to be used for a long time to produce a therapeutic effect. Cytochrome P450 2D (CYP2D) enzymes mediate alternative pathways of neurotransmitter synthesis (i.e. tyramine hydroxylation to dopamine and 5-methoxytryptamine O-demethylation to serotonin), and metabolism of neurosteroids. The aim of our present study was to examine the influence of chronic treatment with the new atypical neuroleptic asenapine on CYP2D in rat brain. In parallel, liver CYP2D was investigated for comparison. Asenapine added in vitro to microsomes of control rats competitively, but weakly inhibited the activity of CYP2D (brain: Ki = 385 μM; liver: Ki = 36 μM). However, prolonged administration of asenapine (0.3 mg/kg sc. for 2 weeks) significantly diminished the activity and protein level of CYP2D in the frontal cortex, nucleus accumbens, hippocampus and cerebellum, but did not affect the enzyme in the hypothalamus, brain stem, substantia nigra and the remainder of the brain. In contrast, asenapine enhanced the enzyme activity and protein level in the striatum. In the liver, chronically administered asenapine reduced the activity and protein level of CYP2D, and the CYP2D1 mRNA level. In conclusion, prolonged administration of asenapine alters the CYP2D expression in the brain structures and in the liver. Through affecting the CYP2D activity in the brain, asenapine may modify its pharmacological effect. By increasing the CYP2D expression/activity in the striatum, asenapine may accelerate the synthesis of dopamine (via tyramine hydroxylation) and serotonin (via 5-methoxytryptamine O-demethylation), and thus alleviate extrapyramidal symptoms. By reducing the CYP2D expression/activity in other brain structures asenapine may diminish the 21-hydroxylation of neurosteroids and thus have a beneficial influence on the symptoms of schizophrenia. In the liver, by reducing the CYP2D activity, asenapine may slow the biotransformation of concomitantly administered CYP2D substrates (drugs) during continuous treatment of schizophrenia or bipolar disorders.

An in vivo microdialysis study of FLZ penetration through the blood-brain barrier in normal and 6-hydroxydopamine induced Parkinson's disease model rats

FLZ (N-[2-(4-hydroxy-phenyl)-ethyl]-2-(2,5-dimethoxy-phenyl)-3-(3-methoxy-4-hydroxy-phenyl)-acrylamide) is a novel synthetic squamosamide derivative and a potential anti-Parkinson's disease (PD) agent. The objective of the present study was to investigate the penetration of free FLZ across the BBB and the effects of P-gp inhibition on FLZ transport in normal and 6-hydroxydopamine (6-OHDA) induced PD model rats. In vivo microdialysis was used to collect FLZ containing brain and blood dialysates following intravenous (i.v.) drug administration either with or without pretreatment with the specific P-gp inhibitor, zosuquidar trihydrochloride (zosuquidar·3HCl). A sensitive, rapid, and reliable ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) technique was developed and validated to quantitate free FLZ levels in the dialysates. No significant differences were observed in the brain/blood FLZ area under the concentration-time curve (AUC) ratio between normal and PD model rats. However, pretreatment with zosuquidar·3HCl markedly increased the AUC ratio in both rat models. In addition, FLZ penetration was similar in zosuquidar·3HCl-pretreated normal and PD rats. These results suggest that P-gp inhibition increases BBB permeability to FLZ, thereby supporting the hypothesis that P-gp normally restricts FLZ transfer to the brain. These findings could provide reference data for future clinical trials and may aid investigation of the BBB permeability of other CNS-active substances.

Amineptine treatment of persistent catatonic symptoms in schizophrenia: a controlled study

BACKGROUND

Data on the treatment response of enduring catatonic phenomena accompanying chronic schizophrenia are few and far between. The aim of this study was to explore the therapeutic effects of add-on amineptine, a dopamine agonist antidepressant in chronic catatonia occurring in schizophrenia.

METHOD

Fifteen subjects with DSM-IV schizophrenia presenting with persistent catatonic features underwent a 15-week, double-blind, placebo-controlled cross-over trial; they were treated for 6 weeks each with amineptine and a placebo, with a 3-week wash-out period in between. The primary outcome measures were the sum scores of the Bush-Francis Catatonia Rating Scale and the Modified Rogers Scale. Changes in other aspects of psychopathology and extrapyramidal side effects (EPS) constituted the secondary outcome measures.

RESULTS

Amineptine augmentation of antipsychotic treatment had no appreciable effect on either of the catatonia ratings. Apart from a statistically significant but clinically negligible improvement in the negative symptom scores, there were no changes in the psychopathology and EPS ratings.

CONCLUSION

The lack of a therapeutic effect of the dopamine agonist amineptine on persistent catatonic signs and symptoms suggests that the dopamine system may not have a decisive role in the pathophysiology of chronic catatonic syndrome arising in the context of schizophrenia.

A randomized, placebo-controlled, double-blind phase 2 study of docetaxel compared to docetaxel plus zosuquidar (LY335979) in women with metastatic or locally recurrent breast cancer who have received one prior chemotherapy regimen

PURPOSE

To determine if concomitant administration of docetaxel plus zosuquidar.3HC1 can prolong progression-free survival in patients with metastatic breast cancer.

METHODS

A randomized, double-blind, multicenter, placebo-controlled clinical trial comparing docetaxel plus 500 mg zosuquidar.3HCl (DZ) with docetaxel plus placebo (DP).

RESULTS

A total of 170 patients were enrolled and randomly assigned to treatment. The median age was 53 years (range, 31-74 years). 81.7% of patients had prior chemotherapy in the adjuvant setting and 18.3% in the neoadjuvant setting. The median progression-free survival time was statistically different between groups [7.2 months (DZ) vs. 8.3 months (DP)]. Once the stratification factor relative to progression following prior chemotherapy was considered, no significant treatment difference existed.

CONCLUSION

The combination of zosuquidar.3HCl plus docetaxel is safe. The analysis of efficacy data is complex, but it can be concluded that there is no difference in progression-free survival, overall survival, or response rate in the study as a whole.

Role of xenobiotic efflux transporters in resistance to vincristine

This study characterized interactions between efflux transporters (P-glycoprotein (MDR1) and multidrug resistance associated proteins (MRPs1-3)) and vincristine (VCR), using cell lines with differential transporter expression, and studied effects of P-glycoprotein inhibition on VCR transport and toxicity. Caco2 (express MDR1, MRPs 1-3), LS174T (express MDR1, MRPs 1, 3), and A549 (express MRPs 1-3) cells were used. To study VCR transport (effective permeability, P(eff)), VCR (1-500 nM) was added to the donor chambers of permeable supports containing Caco2 monolayers, and receiving chamber concentrations were measured. Cytotoxicity experiments were conducted with escalating concentrations of VCR in all cell lines. To determine the contribution of MDR1, experiments were also conducted with LY335979, a specific MDR1 inhibitor. VCR P(eff) was 2 x 10(-6)cm/s in Caco2 cells. LY335979 increased P(eff) in a dose dependent manner (up to 7-fold with 1 microM LY335979) in Caco2 cells. Caco2 and LS174T cell viability decreased significantly when co-incubated with both VCR and LY335979 (1 microM) (P<0.05), however this was not observed in A549 cells. In summary, MDR1 plays an important role in VCR efflux; MDR1 inhibition increased VCR P(eff) in Caco2 cells, and increased VCR cytotoxicity in Caco2 and LS174T cells (both express MDR1), but not A549 cells (minimal MDR1 expression). Inhibition of MDR1 may be a viable strategy to overcome VCR resistance in tumors expressing MDR1, however the presence of other efflux transporters should also be considered, as this will influence the success of such strategies.

Phase I study of the multidrug resistance inhibitor zosuquidar administered in combination with vinorelbine in patients with advanced solid tumours

BACKGROUND

Zosuquidar (LY335979) is an oral P-glycoprotein modulator. This phase I study was designed to determine the maximum tolerated dose (MTD) of zosuquidar in combination with vinorelbine. The effects of zosuquidar on vinorelbine pharmacokinetics were also examined.

DESIGN

Patients with advanced solid tumours were treated with escalating doses of zosuquidar administered every 8-12 h on days 7-9 and 14-16 during cycle 1 then days 0-2, 7-9, and 14-16 from cycle 2 onwards, with vinorelbine 22.5-30 mg/m2 IV on days 1, 8 and 15 every 28 days.

RESULTS

Of 21 patients registered, 19 were treated at four dose levels (zosuquidar 100-300 mg/m2). Two patients had prolonged and febrile neutropenia at the second dose level resulting in a reduction of the dose of vinorelbine in subsequent dose levels. There was another patient with dose-limiting febrile neutropenia at dose level four which resulted in the expansion of the dose level three. Eight patients had stable disease and no objective responses were seen. Vinorelbine pharmacokinetic studies showed reduced clearance when given with zosuquidar.

CONCLUSIONS

The MTD was zosuquidar 300 mg/m2 orally every 12 h for 3 days weekly for 3 weeks with vinorelbine 22.5 mg/m2 IV weekly for 3 weeks every 28 days. Zosuquidar may inhibit vinorelbine clearance to a modest degree.

A Phase I trial of a potent P-glycoprotein inhibitor, zosuquidar trihydrochloride (LY335979), administered intravenously in combination with doxorubicin in patients with advanced malignancy

PURPOSE

Our intention was to (a) to investigate the safety and tolerability of a potent P-glycoprotein modulator, zosuquidar trihydrochloride (LY335979), when administered i.v. alone or in combination with doxorubicin, (b) to determine the pharmacokinetics of zosuquidar and correlate exposure to inhibition of P-glycoprotein function in a surrogate assay, and (c) to compare the pharmacokinetics of doxorubicin in the presence and absence of zosuquidar.

PATIENTS AND METHODS

Patients with advanced malignancies who provided written informed consent received zosuquidar and doxorubicin administered separately during the first cycle of therapy and then concurrently in subsequent cycles. Zosuquidar was given i.v. over 48 h in a cohort-dose escalation manner until the occurrence of dose-limiting toxicity or protocol specified maximum exposure. Doxorubicin doses of 45, 60, 75 mg/m(2) were administered during the course of the trial.

RESULTS

Dose escalation proceeded through 9 cohorts with a total of 40 patients. The maximal doses administered were 640 mg/m(2) of zosuquidar and 75 mg/m(2) of doxorubicin. No dose-limiting toxicity of zosuquidar was observed. Pharmacokinetic analysis revealed that, in the presence of zosuquidar at doses that exceeded 500 mg, there was a modest decrease in clearance (17-22%) and modest increase in area under the curve (15-25%) of doxorubicin. This change was associated with an enhanced leukopenia and thrombocytopenia but was without demonstrable clinical significance. The higher doses of zosuquidar were associated with maximal P-glycoprotein inhibition in natural killer cells.

CONCLUSION

Zosuquidar can be safely coadministered with doxorubicin using a 48 h i.v. dosing schedule.

Phase I Study of Docetaxel in Combination with the P-Glycoprotein Inhibitor, Zosuquidar, in Resistant Malignancies

PURPOSE

To determine the maximum tolerated dose, dose-limiting toxicity, and pharmacokinetics of docetaxel infused over 1 hour when given in combination with oral zosuquidar to patients with resistant solid tumors.

EXPERIMENTAL DESIGN

In cycle 1, patients received docetaxel alone. In subsequent cycles, zosuquidar was administered with docetaxel, which was escalated from 75 to 100 mg/m2. Zosuquidar was escalated from 100 to 300 mg/m2 every 8 hours on days 1 to 3 for a total of 7 doses, or from 400 to 500 mg every 12 hours for 2 doses administered 2 hours before docetaxel. The pharmacokinetics of docetaxel with and without zosuquidar administration were obtained.

RESULTS

Thirty-six of 41 patients completed at least one cycle of docetaxel and zosuquidar. The maximum tolerated dose was docetaxel 100 mg/m2 and zosuquidar 500 mg every 12 hours for 2 doses. The most common toxicity was neutropenia. In 35 patients, zosuquidar produced minimal increases in the docetaxel peak plasma concentrations and area under the curve. Dosing over 3 days with zosuquidar (7 doses) did not show benefit over the 1-day dosing. Of the 36 patients, one patient had a partial response, and 14 patients had disease stabilization.

CONCLUSIONS

Docetaxel at 75 or 100 mg/m2 and zosuquidar 500 mg 2 hours before docetaxel and 12 hours later is well tolerated. Zosuquidar minimally alters the pharmacokinetics of docetaxel, allowing full dose docetaxel to be given with this P-glycoprotein modulator. A Phase II study with this combination in advanced breast carcinoma is underway.

Clinical effects and P-glycoprotein inhibition in patients with acute myeloid leukemia treated with zosuquidar trihydrochloride, daunorubicin and cytarabine

BACKGROUND AND OBJECTIVES

P-glycoprotein (P-gp) is a major cause of multidrug resistance (MDR) in acute myelogenous leukemia (AML) and is thought to contribute to the failure of chemotherapy. Zosuquidar trihydochloride (Z.3HCL) is a potent and selective inhibitor of P-gp which rapidly and effectively inhibits drug efflux.

DESIGN AND METHODS

The aim of this study was to evaluate the clinical effects of Z.3HCL and determine its influence on P-gp activity. Sixteen AML patients were entered into a phase 1 dose ranging clinical trial of Z.3HCL, co-administered intravenously with daunorubicin and cytosine arabinoside (ARA-C). Clinical outcomes, toxicity abd adverse events were assessed. P-gp function was analyzed by flow cytometry. In vitro cytotoxicity was studied using the MTT assay.

RESULTS

Eleven patients achieved a complete remission and one a partial remission with a median survival of 559 (range 38-906) days. Non-hematologic grade 3 and 4 toxicities were seen in 4 patients. Z.3HCL infusion was associated with rapid inhibition of Rh123 efflux in CD56+ cells in 16/16 patients and in CD33+ cells from 6/10 patients. The median inhibition was 95% for CD56+ cells and 85.25% for CD33+ cells was significantly elevated in 6/16 patients. The median IC50, using a MTT assay for daunorubicin, decreased significantly between Z.3HCL modulated and unmodulated cells (n=11,153 and 247 ng/mL respectively, p=0.01).

INTERPRETATION AND CONCLUSIONS

The modulator Z.3HCL is a specific inhibitor of P-gp efflux and can be given safely to patients with AML in combination with induction doses of conventional cytotoxic drugs.

A population pharmacokinetic model for doxorubicin and doxorubicinol in the presence of a novel MDR modulator, zosuquidar trihydrochloride (LY335979)

PURPOSE

To develop a population pharmacokinetic model for doxorubicin and doxorubicinol in the presence of zosuquidar.3HCl, a potent P-glycoprotein inhibitor.

METHODS

The population approach was used (implemented with NONMEM) to analyse doxorubicin-doxorubicinol pharmacokinetic data from 40 patients who had received zosuquidar.3HCl and doxorubicin intravenously (separately in cycle 1 and concomitantly in cycle 2 over 48 h and 0.5 h, respectively).

RESULTS

A five-compartment pharmacokinetic model (including three compartments for doxorubicin pharmacokinetics with two pathways for doxorubicinol formation) best described the doxorubicin-doxorubicinol pharmacokinetics in the presence of zosuquidar.3HCl. Doxorubicin clearance (CL), peripheral volume of distribution (V2) and doxorubicinol apparent clearance (CLm/fm) and apparent volume of distribution (Vm/fm) were 62.3 l/h, 2360 l, 143 l/h and 3150 l, respectively, in the absence or presence of low doses of zosuquidar.3HCl (<500 mg). In the presence of high doses of zosuquidar.3HCl (>or=500 mg), these values decreased by 25%, 26%, 48% and 73%, respectively, and doxorubicinol pharmacokinetics were characterized by a delayed t(max) (24 h versus 4 h), which led to the inclusion of the parallel pathways. A decrease in the objective function ( P<0.005) was observed when the impact of zosuquidar.3HCl was accounted for.

CONCLUSIONS

This integrated parent-metabolite population pharmacokinetic model accurately characterized the increase in doxorubicin and doxorubicinol exposure (1.33- and 2-fold, respectively) in the presence of zosuquidar.3HCl (>or=500 mg) and provided insights into the pharmacokinetic interaction, which may be useful in designing future clinical trials.

A phase I trial of a potent P-glycoprotein inhibitor, Zosuquidar.3HCl trihydrochloride (LY335979), administered orally in combination with doxorubicin in patients with advanced malignancies

PURPOSE

The purpose of this study was to investigate the safety and tolerability of Zosuquidar.3HCl, a potent inhibitor of P-glycoprotein (Pgp), when administered p.o. alone and in combination with doxorubicin and to determine whether Zosuquidar.3HCl affects doxorubicin pharmacokinetics and inhibits Pgp function in peripheral blood natural killer lymphocytes.

EXPERIMENTAL DESIGN

Patients with advanced nonhematological malignancies were eligible for this Phase I trial. Zosuquidar.3HCl and doxorubicin were administered separately during the first cycle of therapy and then administered concurrently. Zosuquidar.3HCl was administered over 4 days, with doses escalated until the occurrence of dose-limiting toxicity. Subsequently, doxorubicin doses were increased from 45 to 75 mg/m(2). Zosuquidar.3HCl, doxorubicin, and doxorubicinol pharmacokinetics were analyzed, and dual fluorescence cytometry was used to determine the effects of Zosuquidar.3HCl on Pgp function in natural killer cells.

RESULTS

A total of 38 patients were treated at nine dose levels. Neurotoxicity was dose-limiting for oral Zosuquidar.3HCl, characterized by cerebellar dysfunction, hallucinations, and palinopsia. The maximum-tolerated dose for oral Zosuquidar.3HCl administered every 12 h for 4 days is 300 mg/m(2). Zosuquidar.3HCl did not affect doxorubicin myelosuppression or pharmacokinetics, and Zosuquidar.3HCl pharmacokinetics were similar in the absence and presence of doxorubicin. Higher plasma concentrations of Zosuquidar.3HCl were associated with greater Pgp inhibition in natural killer cells.

CONCLUSION

Zosuquidar.3HCl can be coadministered with doxorubicin using a 4-day oral dosing schedule, with little effect on doxorubicin toxicity or pharmacokinetics. Further refinement in Zosuquidar.3HCl dosing and scheduling should be explored to optimize Pgp inhibition while minimizing cerebellar toxicity.

Although chemically related to amineptine, the antidepressant tianeptine is not a dopamine uptake inhibitor

We investigated whether the antidepressant tianeptine shares the dopamine uptake inhibitory properties of the chemically related antidepressant amineptine. Tianeptine dose dependently (5, 10, 20, 40 mg/kg IP) increased locomotor activity in mice. This stimulant effect (20 mg/kg IP) was dose dependently prevented not only by the D1 dopamine receptor antagonist SCH 23390 (7.5. 15, 30 microg/kg SC), but also by the D2 dopamine receptor antagonist haloperidol (50, 100, 200 microg/kg IP), in contrast to that elicited by dopamine uptake inhibitors. Where the latter prevent dexamphetamine-induced (3 mg/kg SC) reversion of akinesia in mice pretreated with reserpine (4 mg/kg SC, 5 h before test), tianeptine (20 mg/kg IP, 30 min before test) did not. Tested up to a concentration of 10-4 M, tianeptine did neither inhibit the [3H]dopamine uptake into mouse striatal synaptosomes nor compete in vitro with the specific binding of [3H]WIN 35,428 at dopamine transporters from striatal membranes. Finally, in mice injected IV with a tracer dose of [3H]WIN 35,428 (1 microCi), the highest tested dose of tianeptine (40 mg/kg IP) did not reduce the specific binding of the radioligand to striatal dopamine transporters. It is concluded that the antidepressant effect of tianeptine does not depend upon a blockade of the neuronal dopamine transporter.

[A case of Parkinson syndrome secondary to combined amineptine and bromazepam abuse]

A case report of parkinsonism secondary to chronic abuse of amineptine (3 gr/day) and bromazepam (35 mg/day) in a patient diagnosed of borderline personality disorder is presented. The patient did not take any other drugs and he was not recently on neuroleptic treatment; he recognized the abuse of amineptine, as a stimulant, and the bromazepam abuse, looking for a relief to the excessive anxiety secondary to amineptine. The parkinsonism improved after removing both drugs and taking biperiden and diazepam; lastly the patient was discharged without any medication. The patient did not suffer from other complications associated with amineptine or bromazepam abuse. There are some cases reported of parkinsonism secondary to benzodiazepines but there is none secondary to amineptine. We present a short review of the possible responsible mechanisms, thinking on a complex interaction of both drugs on dopamine and its modulatory systems.

[Sexual dysfunction secondary to SSRIs. A comparative analysis in 308 patients]

The authors analyze the incidence of sexual dysfunction (SD) with different SSRIs (Fluoxetine, Fluvoxamine, Paroxetine and Sertraline) and hence the qualitative and quantitative changes in SD throughout time 308 outpatients (169 women, 139 men; mean +/- SD age = 41 +/- 7) under treatment with SSRIs were interviewed with an SD questionnaire designed for this purpose by the authors including questions about the following items decreased libido, delayed orgasm or anorgasmia, delayed ejaculation inability to ejaculation, impotence and general sexual satisfaction. Patients with the following criteria were included: normal sexual function before SSRIs intake, exclusive treatment with SSRIs or associated with benzodiazepines, previous heterosexual or self-orone current sexual practices. We excluded patients with previous sexual dysfunction, association of SSRIs with neuroleptics, recently hormone intake and significant medical illnesses.

RESULTS

There is a significant increase in the incidence of SD when the physicians ask the patients direct questions (55.29%) versus spontaneous SD reported (14.2%). There are some significant differences among different SSRIs paroxetine provoked more delay of orgasm/ejaculation and more impotence than fluvoxamine, fluoxetine and sertraline (Chi square p < 0.05). Only 22.6% of the patients had a good tolerance about their sexual dysfunction. SD has positive correlation with the dose. The patients experienced substantial improvement in sexual function when the dose was diminished or the drug was withdrawn. Men showed more incidence of sexual dysfunction than women but women's sexual dysfunction was more intense than men. Seven of nine patients (77.7%) experienced total improvement when the treatment was changed to Moclobemide (450 mg/day) and two of four patients (50%) improved when treatment was changed to Amineptine.

T-lymphocyte concentrations of cholecystokinin-8 and beta-endorphin in eating disorders: II. Bulimia nervosa

Concentrations of cholecystokinin-8 (CCK-8) and beta-endorphin (beta-EP) in T-lymphocytes of 26 women with bulimia nervosa (BN) and in 26 age- and sex-matched healthy comparison subjects were measured. Ten patients were then treated with 300 mg/day of fluvoxamine, p.o., and five patients were treated with 300 mg/day of amineptine, p.o., for 4 months. Concentrations of the two peptides were measured again after 1, 2, and 4 months of therapy. Basal CCK-8 values were significantly lower in patients than in healthy subjects. During fluvoxamine therapy, CCK-8 values increased, reaching normal levels by month 4 of treatment. No such increase occurred during amineptine therapy. Baseline beta-EP values were normal in the bulimic patients but had declined by month 4 of fluvoxamine therapy.

T-lymphocyte cholecystokinin-8 and beta-endorphin concentrations in eating disorders: I. Anorexia nervosa

Baseline concentrations of cholecystokinin-8 (CCK-8) and beta-endorphin (beta-EP) were measured in T-lymphocytes from 33 restricting patients with anorexia nervosa (AN-R), 23 binging/purging patients with anorexia nervosa (AN-BP), and 24 healthy volunteers. CCK-8 basal values were significantly lower and beta-EP values significantly higher in AN-R and AN-BP patients than in normal volunteers. Levels of the peptides were measured three more times during a 4-month combined cognitive-behavioral/psychopharmacological treatment (nortriptyline or fluoxetine in AN-R, fluoxetine or amineptine in AN-BP). CCK-8 values fluctuated (nonsignificantly) during each treatment, while beta-EP values decreased (to a significant degree only in fluoxetine-treated AN-R patients).

Metabolism of amineptine in rat, dog and man

After oral administration of amineptine (7-[(10-11)-dihydro-5H-dibenzo(a,d)cycloheptane-5yl] amino heptanoic acid), an original tricyclic antidepressant, seven metabolites were isolated from urine and plasma of rat, dog and man. The metabolic pathways were similar for the three species studied. The two major pathways consisted of the beta-oxidation of the heptanoic side chain leading to pentanoic (first step) and propanoic (second step) side chain metabolites and the hydroxylation of the dibenzocycloheptyl ring on carbon atom 10 (C10) causing the formation of two diastereoisomers. Lactamization by internal dehydration of beta-oxidized metabolites appeared to be a minor route of biotransformation. Conjugation reactions were of minor importance in the rat, in contrast to findings for dog and man. Urinary elimination was the major route of excretion in man while in dog and in rat faecal excretion was predominant.

[Amineptin dependence. Detection of patients at risk. Report of 8 cases]

The authors relate eight cases of amineptine dependency collected between 1980 and 1988 in 7 women and 1 man treated in the CHU of Besançon (France). The pharmacodependency appeared to be limited mainly to an abuse and a psychic dependence, i.e. a compulsive need to use the drug on a periodic (two cases) or continuing (six cases) basis in order to experience its psychomotor stimulant like effect. The used dosages ranged between 1,000 and 2,500 mg per day. The daily dose was divided into little doses, every hour for example. The induction modality was progressive during weeks or months and a stable dose period was then encountered. In one patient only, we observed a progressive increase of the dose without stabilisation of the dose. The withdrawal of amineptine was obtained without problem except in 2 cases where we observed clinical manifestations of anxiety, psychomotor agitation or bulimia during one day. Four years after the beginning, amineptine dependence was still present in 2 patients. In 4 patients we obtained an interruption of the amineptine pharmacodependency for one to three years. We did not see again the two remaining patients. In two cases, the main diagnosis, according to DSM III, was a major personality disorder (borderline). In the six other cases the diagnosis was a bipolar affective disorder (including four cases with only hypomanic episodes only). In these six patients the main characteristic of their affective illness was the association with other psychiatric disorders, especially personality disorders, such as borderline personality in one case and atypical personality with uncontrolled behavior as the main feature, in the 5 other patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of unilateral intrahippocampal injection of MK-801 upon local cerebral glucose utilisation in conscious rats

The effects of unilateral intrahippocampal injections of the non-competitive NMDA receptor antagonist, MK-801, on local cerebral glucose utilisation have been examined in conscious rats using [14C]2-deoxyglucose autoradiography. The intrahippocampal injection of MK-801 (10 nmol) induced significant marked increases in glucose use in the ipsilateral hippocampus molecular layer and dentate gyrus (by 31 and 44%, respectively). Function-related glucose use in brain regions with known neuronal connections with the site of drug administration (e.g. entorhinal cortex, septal nucleus, mamillary body) was minimally altered after intrahippocampal MK-801 administration. Blockade of hippocampal NMDA receptors does not appear to modify activity, as reflected in local glucose utilisation, in hippocampal afferent and efferent circuits in conscious rats.

Comparison of the neuroprotective effects of the N-methyl-D-aspartate antagonist MK-801 and the opiate-receptor antagonist nalmefene in experimental spinal cord ischemia

Both N-methyl-D-aspartate (NMDA)-receptor antagonists and opiate-receptor antagonists have been shown to limit tissue damage after ischemic central nervous system injury. We compared the neuroprotective effects of the noncompetitive NMDA-receptor antagonist MK-801 and the opiate-receptor antagonist nalmefene in a model of global spinal cord ischemia and reperfusion in unanesthetized rabbits. MK-801 (1 mg/kg) or nalmefene (0.1 mg/kg) was administered intravenously 5 minutes after reperfusion. MK-801 treatment and nalmefene treatment each significantly improved the neurologic and histologic outcome compared with saline controls. Differences in these outcome measures between MK-801 treatment and nalmefene treatment did not reach statistical significance. Our results are consistent with the hypothesis that multiple factors, including endogenous opioids and excitatory amino acids, contribute to the secondary tissue injury after central nervous system ischemia. These data also provide further evidence that therapeutic interventions with opiate-receptor antagonists or NMDA antagonists may be beneficial in limiting neurologic dysfunction after ischemic brain or spinal cord injury.

The self-administration of MK-801 can depend upon drug-reinforcement history, and its discriminative stimulus properties are phencyclidine-like in rhesus monkeys

The proposed noncompetitive N-methyl-D-aspartate antagonist MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo(a,d)cyclohepten-5,10-imine maleate] has therapeutic potential as an anticonvulsant and neuroprotectant. Previous research has demonstrated that MK-801 shares many of the biochemical and pharmacological actions of the abused drug phencyclidine (PCP). The purpose of the present study was to determine whether rhesus monkeys would self-administer i.v. MK-801 and to determine whether MK-801 has discriminative stimulus properties similar to those of PCP. Four Rhesus monkeys were trained to press response levers according to fixed-ratio 10 schedules of reinforcement for infusions of cocaine (33 micrograms/kg/injection) or PCP (10 micrograms/kg/injection). Various doses of MK-801 were evaluated during substitution tests to determine whether they would maintain lever pressing. None of the four rhesus monkeys tested self-administered MK-801 when it was offered to them after a recent history of cocaine self-administration. Three of the four monkeys, however, did self-administer MK-801 when provided a history of PCP self-administration. All four rhesus monkeys given drug discrimination training with 80 micrograms/kg PCP and tested with MK-801 generalized from the PCP stimulus in a dose-dependent manner. MK-801 was about 2 to 3 times more potent and had a longer duration of action than PCP. Overall, these results provide further evidence in a primate species of similarities in the behavioral effects of MK-801 and PCP, and suggest that MK-801 may have abuse potential of the PCP type.

[A case of amineptine dependence]

We relate a case of amineptine (Survector) dependence in a patient with a previous history of amphetamine dependence. Under pressure from the family, she came to the hospital with anxiety symptoms which had appeared 48 hours after suspension of the treatment. The product was initially prescribed by a psychiatrist three years previously and she took a dose of 100 mg/day for three months. Approximately one year ago she re-started the treatment on her own initiative, increasing the dose to about 30 tablets/day (3 g) in order to combat against asthenia and to be able to maintain her normal level of activity. In her history we find an episode of amphetamine dependence at 17 years old. We compare the characteristics of this case with other reported cases. Finally some recommendations for a better use of this antidepressant in similar cases are suggested.

NMDA receptor antagonists disrupt the retinotectal topographic map

We tested the effect of two NMDA receptor antagonists, APV or MK801 (with NMDA), and the receptor agonist NMDA on the maintenance of retinal topography in frogs. Topography was assayed by measuring the dispersion of retrogradely labeled ganglion cells following a local HRP injection into the tectum. In untreated tadpoles, labeled cells covered about 5% of the retinal area. In APV- or MK801/NMDA-treated tadpoles, labeled ganglion cells covered 17% and 10% of the retinal area, respectively. Neither treatment with L-APV nor with NMDA disrupts the fidelity of the retinotectal projection. Neither APV- nor NMDA-treated ganglion cell terminals differed from untreated terminals with respect to tangential area, branch number, or branch density. These data support a role for the NDMA receptor in visual system development.

A novel NMDA antagonist, MK-801, impairs performance in a hippocampal-dependent spatial learning task

N-Methyl-d-aspartate (NMDA) receptors have been implicated with the triggering of long-term potentiation, a currently studied physiological model of learning and memory. The compound (+)-5-methyl-10,11-dihydro-5H-dibenzo [a,d] cyclohepten-5,10-imine maleate (MK-801) has recently been classified as a potent and selective NMDA antagonist acting at the associated ion channel. After determination of the highest intraperitoneal dose of MK-801 at which increases in activity (measured in photocell activity cages and 3-arm maze) were not observed (0.2 mg/kg), rats that had been previously trained to obtain food pellets in an 8-arm radial maze up to criterion were tested with 0.1 and 0.2 mg/kg doses. Dose-related decreases in "efficiency" in the task were found. The present findings support the suggestion that NMDA antagonists cause impairments in "working memory" and also support the status of long-term potentiation as a physiological model of memory.

Potentiation of kainic acid epileptogenicity and sparing from neuronal damage by an NMDA receptor antagonist

The time course and severity of the excitotoxic syndrome induced in rats by s.c. injection of 10 mg/kg kainic acid (KA) was modified by pretreatment with MK801, a non-competitive inhibitor of the NMDA receptor, at doses of 0.1, 1 and 10 mg/kg. A dose-dependent increase in the severity of the KA-induced electrographic (EEG) manifestations of epilepsy was seen after MK801. This consisted of an earlier appearance and higher number of EEG seizures, longer time spent in seizures, and an earlier onset of status epilepticus. In contrast, behavioral seizures were increased only in the 0.1 mg/kg MK801 group, but abolished by higher doses. On the contrary, wet dog shakes were progressively reduced with increasing doses of MK801. Four of the 9 animals receiving KA-only group and 3 of the 10 animals in the 1 and 10 mg MK801 groups were sacrificed 5 days after KA. The brain of the KA-only rats presented diffuse gross and microscopic evidence of hemorrhagic necrosis and neuronal damage; the MK801 rats showed only minimal neuronal loss in the CA3 hippocampal sector. This study demonstrates that neuronal damage and epileptiform activity can be dissociated. Furthermore, it confirms the protective effect of MK801 against neuronal damage caused by multiple factors. Lastly, it emphasizes the need for EEG monitoring in order to accurately assess any epileptic/antiepileptic effect.

Evaluation of the glutamate antagonist dizocilipine maleate (MK-801) on neurologic outcome in a canine model of complete cerebral ischemia: correlation with hippocampal histopathology

This study was designed to determine if dizocilipine maleate (MK-801), administered following 11 min of complete ischemia in dogs, could favorably alter neurologic outcome and hippocampal damage. Eighteen dogs were anesthetized and subjected to complete cerebral ischemia by temporary occlusion of the ascending aorta and the venae cavae via a thoracotomy. Five min postischemia, 9 dogs were given dizocilipine 150 micrograms/kg, followed by an infusion of 1.25 microgram/kg/min for 8 h. Control dogs were given equal volumes of placebo. Dogs were evaluated neurologically at 24, 48, and 72 h; thereafter, the brains were perfused, fixed and harvested. There was no significant difference in outcome between dizocilipine- and placebo-treated dogs: 5 of 9 given dizocilipine were normal, 1 was mildly injured and 3 were severely injured or dead. In the control animals given placebo, 3 of 9 were normal, 2 were mildly injured and 4 were moderately to severely injured. Histopathologic examination was limited to the hippocampus. CA1 and CA2,3,4 pyramidal neurons were graded according to degree of injury on a 5-point scale. There were no differences in histopathologic grades between the two groups. However, in both groups combined there was a significant correlation between neurologic outcome grade and histopathologic grade. The only notable systemic effect of dizocilipine appeared to be prolonged sedation which extended beyond 24 h postischemia but was not evident at 48 h postischemia. The authors conclude that more outcome studies in more sensitive models are needed.

Pharmacokinetics of amineptine after single-dose, repeated treatment and study of the at-risk populations

In this paper, three different studies are discussed. First, pharmacokinetics of the tricyclic antidepressant amineptine (Survector) and its main metabolite were investigated in young healthy adults. Amineptine was rapidly absorbed. Mean peak plasma concentrations of amineptine and its metabolite occurred 1 and 1.5 h, respectively, after drug administration. The mean apparent volume of distribution was large: 2.4 L/kg. Elimination was rapid. T 1/2 (half-life) was 0.8 h for amineptine and 2.5 h for the metabolite. The mean apparent plasma clearance of amineptine was high (124.8 L/h). In a second study in young patients, no change in pharmacokinetic parameters was observed after a 10-day course of repeated treatment with the drug. Finally, pharmacokinetics of amineptine and its main metabolite were studied in elderly patients on day 1 and after a repeated administration for 15 days. There was no significant age-linked change in the pharmacokinetics of amineptine even if half-life and area under the curve of the metabolite were all greater in the elderly subjects than in young adults. Pharmacokinetic parameters of amineptine and its metabolite were not affected by repeated administration over 15 days. The pharmacokinetic characteristics of amineptine in elderly subjects do not necessitate any dosage alteration for this population.

In vivo demonstration of the enhancement of MK-801 by L-glutamate

MK-801 infused bilaterally into the nucleus accumbens of rats produced a dose-related increase in locomotor activity that was not blocked by intra-accumbens infusion of haloperidol (2.5 micrograms). Intra-accumbens infusion of L-glutamate (1.0 microgram) was without effect when administered alone, but significantly enhanced the increase in locomotor activity produced by MK-801 (5.0 micrograms). The inactive isomer of MK-801 did not produce hypermotility and L-glutamate did not enhance amphetamine(intra-accumbens)-induced hypermotility. These results extend to an in vivo model electrophysiological and radioligand binding studies demonstrating an enhancement of MK-801 activity by L-glutamate. The results also reinforce the concept that such an enhancement would occur during an escalation of excitatory amino acid levels accompanying pathological overload and, thus, would trigger a compensatory neuronal protection by MK-801.

The glutamate antagonist MK-801 reduces focal ischemic brain damage in the rat

Excessive activation of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptor has been implicated in the sequence of neurochemical events that results in irreversible neuronal damage in cerebral ischemia. The effects of the NMDA antagonist (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate (MK-801) upon the amount of ischemic brain damage has been assessed quantitatively in the lightly anesthetized rat. Focal cerebral ischemia was produced by the permanent occlusion of one middle cerebral artery (MCA), and the animals were killed 3 hours after the arterial occlusion. MK-801 (0.5 mg/kg) was administered intravenously either 30 minutes prior to MCA occlusion or 30 minutes after the induction of ischemia. Pretreatment with MK-801 reduced the volume of ischemic damage both in the cerebral cortex (by 38% compared with untreated rats with MCA occlusion; p less than 0.01) and in the caudate nucleus (by 18% compared with controls; p less than 0.05). Treatment with MK-801, initiated 30 minutes after MCA occlusion, reduced the volume of ischemic damage in the cerebral cortex (by 52% compared with controls; p less than 0.01). The volume of ischemic damage in the caudate nucleus was minimally influenced by MK-801 treatment initiated after MCA occlusion. The antiischemic effects of MK-801 were readily demonstrable despite the hypotension that MK-801 induced in rats anesthetized with halothane (0.5%), nitrous oxide (70%), and oxygen (30%). The potency of MK-801 in reducing ischemic brain damage, even when administered after the induction of ischemia, highlights the potential use of NMDA receptor antagonists for the treatment of focal cerebral ischemia in humans.

Focal cerebral ischaemia in the cat: treatment with the glutamate antagonist MK-801 after induction of ischaemia

The effects of the glutamate N-methyl-D-aspartate receptor antagonist MK-801 in reducing ischaemic brain damage have been examined in anaesthetised cats, with drug treatment being initiated 2 h after the induction of cerebral ischaemia. Focal cerebral ischaemia was produced by permanent occlusion of one middle cerebral artery, and the animals were killed 6 h later. The amount of early irreversible ischaemic damage was assessed at 16 predetermined stereotactic planes. Treatment with MK-801 (5 mg/kg, i.v.) 2 h after middle cerebral artery occlusion reduced significantly the volume of ischaemic damage (from 1,625 +/- 384 mm3 of the cerebral hemisphere in vehicle-treated cats to 792 +/- 385 mm3 in MK-801-treated cats). The demonstration of reduced ischaemic brain damage with MK-801, when the agent is administered after the induction of ischaemia, extends the therapeutic potential of such agents in the treatment of focal cerebral ischaemia in humans.

Analgesic properties of intrathecally administered heterocyclic antidepressants

Antinociceptive activities of heterocyclic antidepressants (HCAs) were studied after intrathecal (i.t.) administration in mice. HCAs with selective norepinephrine reuptake blocking properties (noradrenergic HCAs), such as desipramine and protriptyline, produced different antinociceptive profiles from HCAs with selective serotonin reuptake blocking properties (serotonergic HCAs), such as fluoxetine and citalopram. Noradrenergic HCAs were antinociceptive in all of the three nociceptive tests employed in the present study, i.e., tail-flick (TF) test, i.t. substance P-induced behavioral (SPB) test and intradermal hypertonic saline-induced behavioral (HSB) test. Intrathecal noradrenergic HCAs potentiated systemic or i.t. morphine-induced antinociception in the TF test. Serotonergic HCAs were partially antinociceptive in the SPB and HSB test, but inactive in the TF test. Furthermore, serotonergic HCAs did not enhance the antinociception produced by systemic or intrathecal morphine. The present data suggest that the efficacy of HCAs in the control of chronic pain stems, at least partially, from their action in the spinal cord, their analgesic activities probably involve blockade of monoamine reuptake. and the spinal serotonergic system probably possesses a dual action in regard to spinal nociception, while the noradrenergic system does not.

Butriptyline: human pharmacokinetics and comparative bioavailability of conventional and sustained release formulations

The pharmacokinetics and relative bioavailability of butriptyline from conventional and a sustained release (SR) formulation have been studied in a panel of 14 volunteers. A single oral dose of 75 mg butriptyline hydrochloride was administered and a 2 X 2 latin square design was followed. Pharmacokinetic modelling has shown that the plasma butriptyline concentration/time profile is adequately described by a two-compartment open model; good agreement was obtained for the model-fitted and measured parameters. The SR formulation was shown to possess sustained release characteristics as evidenced by the increase in Tmax for 2.6 to 7.5 h, the decrease in Cmax from 46.5 to 10.3 ng ml-1, and a three-fold increase in 'half-value duration' (HVD). The changes have been achieved without any significant decrease in the relative bioavailability of the SR formulation. The half-life of butriptyline in plasma was about 20 h and was not formulation dependent.

Cyclobenzaprine hydrochloride effect on skeletal muscle spasm in the lumbar region and neck: two double-blind controlled clinical and laboratory studies

A new drug, Cyclobenzaprine hydrochloride (Flexeril), was compared with diazepam (Valium) and placebo in double-blind trials for efficacy in treating spasms and pain in the neck and low back. Complex recording methods involving clinical evaluations (graded), patient self-ratings, goniometry, motion analysis by computer, electromyography of controlled motions and detailed statistical analysis were used. Clinical improvement over two weeks was statistically significant in all treatment groups with a statistically significant preference for Cyclobenzaprine hydrochloride. The most striking improvements recorded were in the electromyographic findings, which showed statistically significant changes for the Cyclobenzaprine group. Clinical muscle spasms are not accompanied by increased myoelectric activity; the reverse is true. With improvement, myoelectric activity in back muscles is augmented during prescribed stressful movements as measured by electromyography and computer analysis combined with complex electrogoniometry.

Plasma levels and bioavailability of cyclobenzaprine in human subjects

Cyclobenzaprine was extensively metabolized in man, less than 1% of the dose being excreted unchanged in the urine. Comparison of areas under plasma level curves (AUC) after oral and intravenous doses suggests that the drug may be partly metabolized in the lumen or during its first passage through the gut wall and/or liver. Average plasma levels of the drug increased with increasing dosage, but the AUC increased less rapidly with increasing dose, possibly because of dose-dependent absorption.

Butaclamol in newly admitted chronic schizophrenic patients: a modified fixed-dose dose-range design

In a double-blind placebo controlled study of newly admitted chronic schizophrenics, an attempt was made to further evaluate the safety, acceptability, and effectiveness of BT in doses of 10, 20, and 40 mg. Significant dose related responses occurred on several behavioral variables by the first week of treatment. Maximum clinical response appeared to be at the 20-40 mg. dose level. Extrapyramidal signs occurred at all doses, but with greater severity at higher doses. Excessive daytime drowsiness occurred in all groups but with longer duration and greater intensity in the 20 mg. group. Rebound insomnia occurred after the abrupt withdrawal of BT at all dose levels suggesting the desirability of further study of its hypnotic properties.

[Clinical experiences with noxiptilin]

Noxiptilin (Elronon) proved to be a good bipolar thymoleptic agent in the clinical test at 3 special clinics. Its stimulating effect on the psychomotor function is more pronounced than its sedative action. Therefore, in cases with the anxious, agitated depressive syndrome the additional therapy with a neuroleptic agent or a sedative tranquilizer may be favourable. N. is well tolerated even at a higher age. The side effects are the same as those of other known thymoleptics.

Noxiptilin (Agedal)--a new tricyclic antidepressant with a faster onset of action? A double-blind, multicentre comparison with amitriptyline

Five psychiatric hospitals in Norway took part in this double blind clinical trial, in which noxiptilin (Agedal) was compared with amitriptyline in hospitalized patients with primary depressive illness. According to total randomization, each patient received either noxiptilin or amitriptyline in semiflexible dosage, usually to a maximum dialy dose of 200-250 mg, for at least three, and possibly six weeks. Thirty patients received noxiptilin and 32 received amitriptyline for at least three weeks. The "total" improvement was assessed in two different ways: 1) By direct global assessment; according to this method, there was a non-significant tendency towards greater improvement on amitriptyline after three and sex weeks, in female and male patients alike. 2) By percentage reduction in total score on Hamilton's rating scale for depression; according to this method, there was a significantly greater improvement on noxiptilin after one week in female but not in male patients. After 2, 3 and 6 weeks there were no significant differences. Thus, this trial seems to support earlier claims that noxiptilin has a faster onset of action than amitriptyline. The two drugs did not differ significantly in their effect on any single symptom, nor in their effect on different types of depression. Both drugs had a better effect in patients with duration of present illness less than three months, than in patients with a duration longer than three months. Noxiptilin had a significantly better effect than amitriptyline in patients with insidious onset of present illness, whereas there was a strong (but non-significant) tendency for a better effect of amitriptyline in patients with a more acute onset of illness. No satisfactory explanation can be offered for this unexpected finding.