Automated determination of pirlindole enantiomers in plasma by on-line coupling of a pre-column packed with restricted access material to a chiral liquid chromatographic column.

A fully automated liquid chromatographic method has been developed for the determination of the enantiomers of pirlindole, an antidepressant drug, in human plasma. The method is based on the use of a pre-column packed with restricted access material (RAM) (LiChrospher ADS RP-4) for sample clean-up coupled to a column containing a cellulose tris-(3,5-dimethylphenylcarbamate) based chiral stationary phase (Chiralcel OD-R) for the separation and quantitative analysis of pirlindole enantiomers. A 50-microl plasma volume was injected directly onto the pre-column using a mixture of phosphate buffer (pH 5.0) and methanol (97:3; v/v) as washing liquid. By rotation of a switching valve, the analytes were then eluted in the back-flush mode with the LC mobile phase. A complete separation of pirlindole enantiomers was obtained in 22 min on the Chiralcel OD-R column, using a mobile phase made of a mixture of phosphate buffer (pH 5.0) containing 50 mM sodium perchlorate and acetonitrile (65:35; v/v). The flow-rate was 0.6 ml/min and the analytes were detected fluorometrically using 295 and 340 nm as excitation and emission wavelengths, respectively. The method was then validated and was found to be linear in the 2.5-200 ng/ml range. The limit of detection was lower than 1 ng/ml. Repeatability and intermediate precision at a concentration of 50 ng/ml were about 1.5 and 3.5%, respectively.

The behavioral effects of acute and chronic JL 13, a putative antipsychotic, in Cebus non-human primates.

RATIONALE: Neuroleptic or antipsychotic drugs are the mainstay of treating acute and chronic psychosis. However, their efficacy is offset by a wide array of side effects, especially extrapyramidal syndromes (EPS). In an attempt to develop novel antipsychotic agents, several animal models have been developed to characterize the profile of new chemical entities. OBJECTIVE: To evaluate the behavioral characteristics of JL 13, a potentially unique antipsychotic agent, three separate studies across a wide dose range in Cebus monkeys were conducted and compared with two studies of oral and parenteral haloperidol. METHODS: Twelve Cebus monkeys were tested with single i.m. doses of JL 13 (0.1-2.5 mg/kg), single p.o. doses (1.0-50.0 mg/kg), and 35 days of continuous p.o. (up to 25 mg/kg) treatments and were blindly evaluated. The same twelve monkeys were also tested with haloperidol i.m. (0.01-0.25 mg/kg) and nine of the monkeys also received haloperidol p.o. (0.1-5.0 mg/kg). Behaviors scored included sedation/arousal, locomotor activity, EPS of parkinsonism and dystonia, as well as reactivity. RESULTS: JL 13 produced mild to moderate and dose-related increased sedation and decreased locomotor activity. Minimal decreases in eye blinking rates were also noted as a consequence of sedation. Mild dystonia and parkinsonian symptoms of slow movement developed at the highest dose tested of 50 mg/kg p.o. in only 6 of 12 monkeys. This is 50 times higher than oral doses of haloperidol that would be needed to produce similar EPS effects. Dose-related EPS of dystonia and bradykinesia occurred in relation to decreased locomotor activity and reactivity to stimuli with haloperidol i.m. and p.o., which are features characteristically seen with traditional neuroleptics. CONCLUSIONS: The behavioral effects of JL 13 in non-human primates suggest this compound is well tolerated and may have a favorable antipsychotic benefit/risk ratio in the clinic, especially if antipsychotic efficacy occurs at doses well below those that can cause EPS.

Novel inhibitors of the sodium-calcium exchanger: benzene ring analogues of N-guanidino substituted amiloride derivatives.

A series of N-guanidino substituted 2,4-diamino-5-carbonylguanidine molecules related to amiloride were synthesised and evaluated for their ability to inhibit the sodium-calcium exchanger in rat insulinoma cells (RINm5F) and human platelets. Specific chemical pathways were used to prepare the benzene derivatives designed as bioisosteric analogues of the pyrazine derivatives of amiloride. Several so-called 'simplified analogues', where some substituents of amiloride were omitted or replaced, were also prepared and included in the biological evaluation. The inhibitory potency of the sodium-calcium exchanger was screened on both cell types by measuring their effect on 45Ca(2+) uptake. Among the most active compounds, N-(2-amino-5-chloro-4-nitrobenzoyl)-N'-(1-naphtylmethyl)guanidine (IC(50)=3.4 microM) was found more active than amiloride (IC(50)=690 microM) and 3,4-dichlorobenzamil (IC(50)=15.2 microM), the reference inhibitor.

Electrooxidation potential as a tool in the early screening for new safer clozapine-like analogues.

The chemical modification of clozapine (1) has permitted the finding of new analogues, e.g., olanzapine (2), quetiapine (3), 5-(4-methylpiperazin-1-yl)-8-chloropyrido[2,3-b][1,5]benzoxazepine fumarate (9), with a clinical or psychopharmacological profile similar to that of clozapine. However, when developing new derivatives, the designers are discouraged by the development of clozapine-induced agranulocytosis. Different researchers have raised the role played by the oxidizability of the molecule in such a deleterious effect. In the present paper, we examined the oxidation profile (direct scavenging abilities, efficacy in inhibiting lipid peroxidation, and electrooxidation potential) of newly developed methoxy and trifluoromethylsulfonyloxy analogues related to clozapine, some of them being described as putative antipsychotic. The oxazepine derivative 7, unlike the other diazepine derivatives (6, 10--12), was not readily oxidized. Using a statistical predictive model for hematotoxicity previously described, 7 was found in the cluster of potentially nontoxic compounds while diazepine derivatives 6 and 10-12 were classified as potentially toxic compounds. Among these original compounds, 7, which presents a preclinical clozapine-like profile and a low sensitivity to oxidation, could be a promising antipsychotic candidate with low side effects. Considering the tricyclic derivatives examined so far, some elements of structure-oxidation relationship (SOR) might be pointed out. Regarding the nature of the tricyclic ring substituent, from the most to the least sensitive to oxidation, the sequence was as follows: HO > Cl > CH(3)O > CF(3)SO(2)O. The nature of the tricyclic ring influenced also the sensitivity to oxidation; the diazepine moiety appeared to be the most reactive ring compared to oxa- and thiazepine congeners. These parameters could be advantageously integrated in the early design of new safer clozapine-like analogues.

The inclusion of fluoxetine into gamma-cyclodextrin increases its bioavailability: behavioral, electrophysiological and pharmacokinetic studies.

The inclusion of a drug into cyclodextrin generally results in the modification of its physical and chemical properties and sometimes can increase its oral bioavailability. The aim of this study was to compare the effects of the fluoxetine HCl/gamma-cyclodextrin complex to that of traditional fluoxetine HCl. In the forced swimming test in mice, fluoxetine HCl/gamma-cyclodextrin was more effective than fluoxetine HCl, the ED30s being, respectively, 9.5 and 16.9 mg/kg PO. Both compounds (10 mg/kg PO) were able to reduce the firing rate of dorsal raphe neurons in the rat. However, between-groups comparisons showed no significant differences between fluoxetine HCl treated animals and the vehicle group, while fluoxetine HCl/gamma-cyclodextrin appeared significantly more effective than vehicle from minute 25 of the measurement period. In healthy volunteers, the relative oral bioavailability, calculated as the ratio AUC 0-infinity fluoxetine HCl/gamma-cyclodextrin on AUC 0-infinity fluoxetine HCl (20 mg PO), was equal to 249.9%. The three experiments taken together suggest that the complexation of fluoxetine HCl into gamma-cyclodextrin increases its pharmacological efficacy in animals, this effect being related to an enhancement of its oral bioavailability as demonstrated in human healthy subjects.

Oxidation sensitivity may be a useful tool for the detection of the hematotoxic potential of newly developed molecules: application to antipsychotic drugs.

Some antipsychotic agents have been found to produce agranulocytosis and aplastic anemia. The oxidation phenomena and/or the formation of free radicals has been suggested to be causally related to various hematological disorders, e.g., agranulocytosis. Using five experimental conditions, we tested the oxidative potential of compounds with and without a history of hematological side effects, e.g., agranulocytosis and aplastic anemia. A statistical analysis was undertaken for each experimental condition and a multivariate analysis combining all results was performed. Two peroxidase-induced free radical models did not successfully discriminate between drugs with and without a history of causing hematologic problems (<70%). The lipid peroxidation system provided even less satisfactory discrimination, with only 56.25% correct classification. However, an 87.5% correct classification was obtained when using the oxidation potentials of these drugs determined at pH 4.7 and at pH 7.4. A multivariate analysis taking into account the five variables provided 87.5% success in classification. The two clusters were better discriminated in terms of a "distance coefficient." In a second analysis, the putative antipsychotic pyridobenzodiazepine analogues (JL5, JL8, JL18, and JL25) were classified in the cluster of toxic compounds, while the oxa- and thiazepine analogues (JL2, JL3, and JL13) were classified as nontoxic compounds. On the other hand, a few metabolites of clozapine and fluperlapine were classified in the toxic compound group. The procedure described herein is, to our knowledge, the first which classifies molecules of different structures as well as different pharmacological profiles according to their hematotoxic potential. Such a procedure could be used to predict drug-induced hematological side effects.

Effects of JL 3, a putative antidepressant, on rat noradrenergic and serotonergic systems.

Using in vitro electrophysiological procedures, we confirm the inhibitory effect of 10-(4-methylpiperazin-1-yl)pyrido[4,3-b][1, 4]benzothiazepine (JL 3), on dorsal raphe serotonergic (IC(50)=14 microM) and noradrenergic neurons (IC(50)=4.5 microM). The effect on dorsal raphe neurons was reduced by N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinyl- cyclohexanecarboxamide (WAY-100635), suggesting the importance of 5-HT(1A) receptor stimulation. Yohimbine, and ritanserin, to a lesser extent, blocked the inhibitory effect of JL 3 on locus coeruleus neurons indicating that alpha(2)-adrenoceptors and 5-HT(2A) receptors may be implicated in the effects. Because of its negligible alpha(2)-adrenoceptor affinity, the effect of JL 3 on locus coeruleus neurons, would have to be indirect. JL 3 may interfere with the norepinephrine transporter site (IC(50)=0.34 microM). JL 3 tended to reinforce the hypertensive effect of norepinephrine, while it strongly inhibited the hypertensive effect of tyramine, further indicating an interaction at the norepinephrine transporter site level.

Facilitatory effects of chronically administered citicoline on learning and memory processes in the dog.

1. Citicoline (cytidine (5') diphosphocholine) has been shown to reverse aging-induced memory deficits, scopolamine-induced amnesia and nucleus basalis magnocellularis lesion-induced learning impairment. 2. This study aimed to evaluate the effects of citicoline on learning and retrieval processes in a complex differential reinforcement of response duration schedule in normal dogs. 3. The effects of citicoline on a stabilized performance were also measured in order to be able to differentiate specific memory effects from non specific influences on the motor, neuro-vegetative and motivational systems. 4. The results demonstrate that citicoline can exert facilitatory effects on learning and memory but also on retrieval processes. The complete absence of effects on the stabilized performance and on the motor, neuro-vegetative and motivational systems constitutes arguments in favour of a selectivity of action on the memory processes.

Short- and long-term effects of molsidomine retard and molsidomine nonretard on exercise capacity and clinical status in patients with stable angina: a multicenter randomized double-blind crossover placebo-controlled trial.

A multicenter, randomized, double-blind, crossover, placebo-controlled study was conducted in 90 isosorbide dinitrate responders showing stable angina to compare the efficacy of molsidomine retard, 8 mg b.i.d., with that of molsidomine, 4 mg t.i.d., for 6 weeks. Total work performance (workload x min) was significantly improved, compared with baseline and placebo until 8 and 12 h after molsidomine and molsidomine retard administration, respectively. ST-segment depression decreased significantly under the two treatments at 60 W as well as at maximal exercise. The rate-pressure product (heart rate x systolic blood pressure) decreased and increased significantly at submaximal and maximal exercise level, respectively. All these effects remained significant after 6-week treatment, with only the ST segment showing a nonsignificant tendency to improvement at maximal work. The frequency of anginal attacks and of sublingual nitroderivative-tablets consumption decreased significantly with molsidomine, 4 mg, and molsidomine retard, 8 mg. However, overall results showed that the latter form reduces myocardial ischemia more efficiently at submaximal exercise level, has a more prolonged effect on exercise tolerance, and maintains it at a somewhat higher level after 6-week treatment.

Simultaneous determination of pirlindole enantiomers and dehydropirlindole by chiral liquid chromatography.

Liquid chromatography was employed for the determination of pirlindole enantiomers and its oxidation product dehydropirlindole (DHP). The direct separation of pirlindole enantiomers and DHP was achieved on a cellulose tris-(3,5-dimethylphenylcarbamate) chiral stationary phase (Chiralcel OD-R). Acetonitrile was used as the organic modifier and sodium perchlorate was used as an ionic additive in the mobile phase. The influence of acetonitrile and sodium perchlorate concentrations on enantioselectivity and achiral selectivity towards DHP was investigated in order to find suitable conditions for the determination of low amounts of each analyte. The mobile phase selected consisted of a mixture of acetonitrile and phosphate buffer (pH 5.0) containing sodium perchlorate (0.05 M) (35:65, v/v) and the UV detector was set at 220 nm. The method developed was validated and was found to be linear in the 0.1-5 microg ml(-1) range (r2 = 0.999 for the three compounds). Repeatability and the intermediate precision for the three analytes at a concentration of 0.1 microg ml(-1) were about 3 and 4%, respectively. This concentration corresponds to the quantification of 0.1% for the minor enantiomer. Actual determinations of enantiomeric purity for single enantiomers of pirlindole were performed.

Comparative study of pirlindole, a selective RIMA, and its two enantiomers using biochemical and behavioural techniques.

The interaction with monoamine oxidase A (MAO-A) and B has been shown to be sensitive to the absolute configuration of molecules. Therefore, the aim of this study was to compare the effects of the racemic pirlindole (a selective and reversible MAO-A inhibitor) and its two enantiomers using biochemical techniques (in vitro and ex vivo determination of rat brain MAO-A and MAO-B activity) and behavioural models (forced swimming test and reserpine-induced hypothermia and palpebral ptosis test). In vitro, the MAO-A IC50 of (+/-)-pirlindole, R-(-)-pirlindole and S-(+)-pirlindole were 0.24, 0.43 and 0.18 microM, respectively. Ex vivo, their ID50 were 24.4, 37.8 and 18.7 mg/kg i.p. The differences between the three compounds were not significant, with a ratio between the two enantiomers [R-(-)/S-(+)] of 2.2 in vitro and 2.0 ex vivo. MAO-B was only slightly inhibited. In the forced swimming test and the reserpine-induced hypothermia and ptosis model, the three compounds had an antidepressant profile. In the forced swimming test, the minimal effective dose ratio between the R-(-) and the S-(+) was again around 2.0. The behavioural observations were thus clearly in accordance with the biochemical data.

Enantiomeric separation of pirlindole by liquid chromatography using different types of chiral stationary phases.

The enantioseparation of pirlindole by liquid chromatography (LC) was investigated using three different chiral stationary phases (CSPs) containing either cellulose tris-(3,5-dimethylphenylcarbamate) (Chiralcel OD-R), ovomucoid (OVM) or beta-cyclodextrin (beta-CD). The effects of the mobile phase pH on retention, enantioselectivity and resolution were studied. Methanol and acetonitrile were tested as organic modifiers while the influence of the addition to the mobile phase of sodium alkanesulfonates or sodium perchlorate was also investigated. Sodium perchlorate was only used on the Chiralcel OD-R column while sodium alkanesulfonates were tested as mobile phase additives on the three kinds of CSPs. The enantioseparation of pirlindole could be obtained on all CSPs tested, the best results with respect to chiral resolution being achieved on the Chiralcel OD-R and the OVM columns. The use of sodium octanesulfonate (NaOS) was found to improve the enantioseparation of pirlindole on the OVM column while enantioselectivity was considerably enhanced by addition of sodium perchlorate on the Chiralcel OD-R column.

Double-blind randomized controlled study of the efficacy and tolerability of two reversible monoamine oxidase A inhibitors, pirlindole and moclobemide, in the treatment of depression.

The aim of this double-blind randomized study was to compare the efficacy and the tolerability of moclobemide (300-600 mg daily) and pirlindole (150-300 mg daily), two reversible inhibitors of MAO-A (RIMAs), in the treatment of depression. In total 116 patients were included in the trial, 111 patients (52 patients on pirlindole and 59 patients on moclobemide) were evaluable for efficacy and safety, and 77 patients completed the whole study (42 days of administration). Both treatments produced highly significant improvements in the Hamilton Depression Rating Scale (HDRS) score, the Hamilton Anxiety Rating Scale (HARS) score and the Montgomery-Asberg Rating Scale (MADRS) score from day 7 to day 42. The pattern of development of the three scores in the two groups did not differ significantly. After 42 days of treatment, an improvement of > or = 50% in the HDRS score was noted in 80% and 67% of patients in the pirlindole and moclobemide groups, respectively. A total of 30 (58%) patients on pirlindole and 33 (56%) patients on moclobemide experienced side-effects that were considered to be possibly or probably related to the medication. The differences between the two drugs were non-significant for all types of side-effect, with the exception of dry mouth and tachycardia, which were significantly more frequent with moclobemide.

Pirlindole: a selective reversible inhibitor of monoamine oxidase A. A review of its preclinical properties.

Pirlindole is a tetracyclic compound that has been characterized as a potential antidepressant drug. It has pharmacological characteristics in common with both tricyclic antidepressants and classical irreversible monoamine oxidase inhibitors. Its main mechanism of action consists of a selective and reversible inhibition of monoamine oxidase A. Secondarily, it exerts an inhibitory effect on noradrenaline and 5-hydroxytryptamine reuptakes. It has no effect on the dopaminergic and cholinergic systems. It has only a low potential for amplifying tyramine and noradrenaline pressor effect, which makes one expect that it will not be at the basis of a 'cheese effect'. Pirlindole has an absolute bioavailability of between 20 and 30% due to an extensive first-pass effect. Orally, the Tmax varies between 2.5 and 6 h in the rat and 0.8 and 2 h in the dog. Two phases of elimination (7.5 and 34-70 h) are measured in the rat and three phases in the dog (1.3, 10.8 and 185 h); it is extensively metabolized. The rat eliminates mainly unconjugated products while the dog eliminates mostly conjugated products. Acute and chronic toxicological studies have not revealed potentially dangerous effects of the drug at the usual doses. It does not present measurable mutagenic, clastogenic or carcinogenic properties. Thus, pirlindole shows pharmacological, pharmacokinetic and toxicological properties which make it suitable for the management of depression.

JL13, a pyridobenzoxazepine compound with potential atypical antipsychotic activity: a review of its behavioural properties.

The search for an improved clozapine-like compound has resulted in the selection of a new molecule: JL13 (5-(4-methylpiperazin-1-yl)-8-chloro-pyrido[2,3-b][1,5] benzoxazepine fumarate). Like clozapine, JL13 did not antagonize apomorphine-induced stereotypy and did not produce catalepsy but antagonized apomorphine-induced climbing in rodents (ID50 = 3.9 mg kg-1 s.c.). It was inactive against d-amphetamine-induced stereotypy but antagonized d-amphetamine-induced hyperactivity in the mouse (ID50 = 4.4 mg kg-1 i.p.). JL13, like clozapine, was able to antagonize (+/-)-DOI-induced head-twitches in the mouse (ID50 = 2.0 mg kg-1 i.p.). In the open-field test in the rat and forced swimming test in the mouse a high similarity was noted between the two drugs in the same range of doses. In a complex temporal regulation schedule in the dog, JL13 showed a high resemblance with clozapine without inducing sialorrhea, palpebral ptosis or any significant motor side effects. In rats trained to discriminate clozapine, JL13 (10 mg kg-1 i.p.) induced a high level of generalization (70%) to clozapine. In a drug discrimination procedure in the squirrel monkey, JL13 (3-10 mg kg-1 i.m.) produced a full substitution of clozapine. On the basis of these preclinical data, it is thus predicted that JL13 would be a promising atypical antipsychotic drug.

A double-blind randomized placebo-controlled study of the efficacy and safety of pirlindole, a reversible monoamine oxidase A inhibitor, in the treatment of depression.

The efficacy and safety of pirlindole (300 mg/day), a new reversible inhibitor of monoamine oxidase A, have been evaluated in a multicentre placebo-controlled double-blind randomized trial in 103 in-patients suffering from unipolar major depression (DSM-III-R 296.2, 296.3) over a 42-day period after a run-in placebo period of 6 days. Pirlindole produced a significantly greater decrease than placebo in the Hamilton depression score (from day 28), the Hamilton anxiety score (from day 28) and the Montgomery-Asberg depression score (on day 42). On day 42, the Hamilton depression score was < or = 7, > or = 8 and < or = 15, or > or = 16 in 21%, 45% and 34%, respectively, in the placebo group compared to 72%, 24% and 3.4%, respectively, in the pirlindole group (P < 0.001). The differences between the two groups in terms of tolerance and safety were not statistically significant.

Dibenzoazepine analogues: the electrophysiological properties of JL3, a potential atypical antidepressant.

JL3, 10-(4-methylpiperazin-1-yl)pyrido[4,3-b][1,4]benzothiazepine, has potent antidepressant-like activity in Porsolt's test in mice. Therefore, its influence on the electrical activity of central monoaminergic neurons was investigated in rats anaesthetized with chloral hydrate. JL3 induced a marked decrease of the firing rate of dorsal raphe serotonergic neurons (ID50 = 3.87 +/- 0.57 mg kg-1) and of locus coeruleus noradrenergic neurons (ID50 = 2.63 +/- 0.35 mg kg-1). The drug did not modify the electrical activity of A10 dopaminergic neurons. JL3 does not block amine uptake but it has affinity for 5-HT1A and 5-HT2 receptors. It is speculated that serotonergic mechanisms could play a role in the electrophysiological effects of JL3.

New dibenzazepine derivatives with disinhibitory and/or antidepressant potential: neurochemical and behavioural study in the open-field and forced swimming tests.

Original bioisosteric analogues of clozapine were evaluated for potential disinhibitory and/or antidepressant effects using the open-field test in the rat and Porsolt's forced swimming test in the mouse. Attempts to relate the behavioural results to the binding affinities for dopamine (D1, D2), serotonin (5-HT(2)) and muscarinic (M) receptors were also undertaken. In the open-field test, two main profiles were observed. The first profile corresponded to disinhibitory molecules resembling diazepam and ritanserin. The second profile corresponded to antipsychotic compounds resembling either typical (haloperidol, clothiapine) or atypical (clozapine) neuroleptics. The results obtained in the forced swimming test confirmed the neuroleptic-like activity of the second group of compounds, while two compounds of the first group (JL 3 and JL 26) showed an antidepressant-like activity, JL 3 being as active as imipramine. While it was not possible to relate the first profile to any binding interaction, a relation could be established among the second group of compounds between the typical or atypical antipsychotic behavioural profile and the 5-HT(2)/D2 ratio.

Modulation of the clozapine structure increases its selectivity for the dopamine D4 receptor.

Clozapine has a more marked affinity for the recently cloned dopamine D4 receptor than for the dopamine D2 receptor. In the search for a selective ligand for the dopamine D4 receptor, useful as a pharmacological tool or as a potent atypical antipsychotic, a pyridobenzodiazepine derivative bioisoster of clozapine, JL 18, 8-methyl-6-(4-methyl-1-piperazinyl)-11H-pyrido [2,3-b][1,4]benzodiazepine, was found to be the most dopamine D4-selective ligand belonging to the diarylazepine class. Indeed, JL 18 binds to the dopamine D4 receptor with affinity up to 25 times superior to that for the dopamine D2 receptor and presents reduced affinities for other receptors.