High performance liquid chromatographic determination of ultra traces of two tricyclic antidepressant drugs imipramine and trimipramine in urine samples after their dispersive liquid-liquid microextraction coupled with response surface optimization.

Dispersive liquid-liquid microextraction (DLLME) coupled with high performance liquid chromatography by ultraviolet detection (HPLC-UV) as a fast and inexpensive technique was applied to the determination of imipramine and trimipramine in urine samples. Response surface methodology (RSM) was used for multivariate optimization of the effects of seven different parameters influencing the extraction efficiency of the proposed method. Under optimized experimental conditions, the enrichment factors and extraction recoveries were between 161.7-186.7 and 97-112%, respectively. The linear range and limit of detection for both analytes found to be 5-100ng mL(-1) and 0.6ng mL(-1), respectively. The relative standard deviations for 5ng mL(-1) of the drugs in urine samples were in the range of 5.1-6.1 (n=5). The developed method was successfully applied to real urine sample analyses.

Acción de los antidepresivos sobre las fases del sueño: componentes tónicos y fásicos / Action of antidepressants on the phases of sleep: tonic and phasic components

Se presentan los efectos descritos para los antidepresivos sobre el sueño (actividad REM, sueño de ondas lentas, continuidad del sueño, microestructura y ensoñaciones). Se describen como numerosos, diversos y no siempre consistentes, con lo que se reconoce la limitación del conocimiento actualmente disponible. Se exponen las diferencias en el perfil farmacológico que podrían estar implicadas, básicamente: a) la participación del sistema serotoninérgico, aunque con implicación controvertida de los distintos subtipos de receptores, en la supresión REM; b) el antagonismo de los receptores 5HT2A/2C, el incremento del sueño de ondas lentas y la promoción de la continuidad del sueño; c) la participación en este último efecto del antagonismo α1 y H1, y d) la limitada responsabilización del sistema noradrenérgico. Se explicita la compleja relación entre ensoñaciones, fármacos antidepresivos, sueño REM y depresión. También se identifican las diferencias que implican los efectos agudos frente a los crónicos; las distintas dosis y perfiles farmacocinéticos en voluntarios sanos frente a pacientes deprimidos, y los cambios en la macroestructura (evaluación tradicional visual) frente a la microestructura (evaluación cuantitativa computarizada). Con el objetivo de disponer de una descripción más precisa de la relación entre la depresión, el sueño y el efecto antidepresivo, se sugiere la necesidad de llevar a cabo estudios en los que directamente se comparen distintos antidepresivos, utilizando diseños que comporten el control de todas las variables de confusión identificadas (AU)

The effects described for antidepressants on sleep (REM activity, slow wave sleep (SWS), sleep continuity, microstructure of sleep and dreams) are presented. These are described as numerous, diverse and not always consistent, the reason why the limitation of knowlege at the moment available is recognized.The differences in the pharmacological profile that could be implied basically are exposed below: (i) participation of serotonergic system although with a controversial implication of different types of receptors in REM sleep supression; (ii) the antagonism of 5HT 2A/2C receptors, the increase of SWS and the promotion of sleep continuity; (iii) the participation in this last effect of α1 and H1 antagonism; (iv) the limited implication of noradrenergic system. The complex relationship between dreams, antidepressants, REM sleep and depression is shown. Differences involved between acute effects vs chronic effects, different dosages and pharmacokinetic profiles in healthy volunteers vs depressed patients and changes in the macrostructure (traditional visual evaluation) vs microstructure (quantitative computerized evaluation) are also recognized. With the aim of having a more precise description of the relationship between depression, sleep and antidepressant effect, the necessity to carry out studies comparing directly different types of antidepressants using designs to control all the identified variables of confusion, is suggested (AU)

Trimipramine pharmacokinetics after intravenous and oral administration in carriers of CYP2D6 genotypes predicting poor, extensive and ultrahigh activity.

OBJECTIVE: The tricyclic antidepressant trimipramine is one of the drugs with the most pronounced differences in pharmacokinetics caused by the CYP2D6 genetic polymorphism. However, the effect of CYP2D6 genotype on steady state kinetics and on bioavailability has not been studied so far. In addition, we were interested in trimipramine pharmacokinetics in genetically defined ultra rapid metabolizers. METHODS: We studied intravenous and multiple dose oral application of 50 mg trimipramine in five, seven, and three healthy volunteers with CYP2D6 genotypes predicting deficient, highly active and ultrarapid metabolism. The latter group included carriers of one wild-type and one duplication allele. Trimipramine and desmethyltrimipramine concentrations were measured by HPLC over a time interval of 72 h after intravenous and after one oral application. RESULTS: Both bioavailability and systemic clearance significantly depended on CYP2D6 genotype with a linear gene dose relationship. Mean bioavailability was 44, 16 and 12% in carriers of zero, two and three active genes of CYP2D6, respectively, and the corresponding data for systemic clearance were 12.0, 24.2, and 30.3 l/h. Consequently, the mean total oral clearances were 27.3, 151, and 253 l/h in poor, extensive and ultrarapid metabolizers. CONCLUSIONS: High bioavailability combined with low systemic clearance of trimipramine in poor metabolizers of CYP2D6 substrates results in a very high exposure to trimipramine with the risk of adverse drug reactions. On the other hand, the extremely high systemic and presystemic elimination may result in sub-therapeutic drug concentrations in carriers of CYP2D6 gene duplications with a high risk of poor therapeutic response.

Effects of polymorphisms in CYP2D6, CYP2C9, and CYP2C19 on trimipramine pharmacokinetics.

Little is known about the impact of cytochrome P450 polymorphisms on the metabolism of trimipramine, which is still widely used as antidepressant due to its positive effect on sleep patterns. A single oral dose of 75 mg trimipramine was given to 42 healthy volunteers selected according to their CYP2D6, CYP2C19, and CYP2C9 genotypes. The reference group included 8 subjects with homozygous active wild-type genotypes of all 3 enzymes (EM). This group was compared with 7 intermediate (IM) with 1 and 7 poor metabolizers (PM) with zero active alleles of CYP2D6 and CYP2C19, respectively, and with 4 subjects with the genotype CYP2C9*3/*3. Pharmacokinetics of trimipramine and its demethylated metabolite strongly depended on the CYP2D6 genotype. Median oral clearance of trimipramine was 276 L/h (range 180-444) in the reference group but only 36 L/h (range 24-48) in CYP2D6 PMs (P < 0.001). These differences could only be explained by an effect of CYP genotypes on both parameters, systemic clearance and bioavailability, the latter being at least 3-fold higher in CYP2D6 PMs than in the reference group. The desmethyltrimipramine area under the concentration-time curve was 40-fold greater in CYP2D6 PMs than in the reference group (1.7 vs. 0.04 mg/L x h in EMs), but below the quantification limit in most carriers of deficiencies of CYP2C19 or CYP2C9. This indicates that both CYP2C enzymes contribute to the demethylation of desmethyltrimipramine and CYP2D6 to further metabolism.

abcb1ab P-glycoprotein is involved in the uptake of citalopram and trimipramine into the brain of mice.

The phenomenon of a heterogeneous response to the same drug in different patients is well-known. An important reason is that, even at equal concentrations, the bioavailability of a drug depends on the interaction of the drug with the blood-brain barrier (BBB). In part, this is due to the drug-transporting P-glycoprotein (P-gp), a product of the multiple drug resistance gene (ABCB1), which can transport drugs against a concentration gradient across the BBB back into the plasma and thereby reduce the bioavailability in the brain. In the present study, we have examined the uptake of the antidepressants citalopram and trimipramine into the brain of abcb1ab knockout mice compared with controls. One hour after s.c. injection of the drugs, concentrations of the two drugs and of the metabolite d-trimipramine in brain, spleen, kidney, liver and plasma were measured with HPLC. Significantly higher brain concentrations in knockout mice, showing that these drugs are substrates of P-gp and that the presence of P-gp reduces the effective bioavailability of these substances in the brain. The results of our study contradict an earlier report that citalopram is not actively transported from endothelial cells. These results were derived from an in vitro study, showing that due to the complexity of the BBB-drug interaction, it is difficult to transfer results from in vitro studies to the in vivo situation. We hypothesize that inter-individual differences in the activity of the ABCB1 gene can account in part for the great variation in clinical response to antidepressants in psychiatric patients, even at comparable plasma levels.

Enantiomers' potential in psychopharmacology--a critical analysis with special emphasis on the antidepressant escitalopram.

Stereochemistry is now influencing most areas of pharmacotherapy, with a growing awareness in the field of psychiatry and, more specifically, depression. This is due to the fact that the enantiomers of many chiral drugs may have distinct pharmacological, pharmacokinetic and/or pharmacogenetic profiles. Consequently, in some instances there may be an advantage in using a single enantiomer over the racemic form-thus providing a basis for the development of new therapeutic agents, as well as the potential to improve current treatments. This review highlights some of the potential advantages and disadvantages that using single enantiomers might offer. The principles are exemplified through reference to the stereoselective properties of several established chiral psychotropic drugs, including thioridazine, methadone, trimipramine, mianserin, mirtazapine, fluoxetine and citalopram. Emphasis is given to the treatment of depression and how the potential of one pure enantiomer-escitalopram, the S-enantiomer of the selective serotonin reuptake inhibitor citalopram-appears to be fulfilling its preclinical promise in the clinic.

Drug accumulation and elimination in Calliphora vicina larvae.

Calliphora vicina larvae were fed on drug-laden muscle from three suicides involving amitriptyline, temazepam and a combination of trazodone and trimipramine; triplicate daily harvestings were analysed. The limit of detection for all four drugs was 0.01 micrograms drug/g larvae. Mean drug concentrations (microgram/g) in the initial muscle were:amitriptyline, 2.68; temazepam, 4.04; trazodone, 21.56; and trimipramine, 19.58. Larval rearings for days 4-8 (15 larval samples per drug) had mean and ranges of drug concentrations (microgram/g) of 0.10 (r, 0.02-0.24) for amitriptyline; 0.52 (r, 0.26-0.78) for temazepam; 0.13 (r, 0.05-0.32) for trazodone; and 0.28 (r, 0.10-0.59) for trimipramine. After day 8 there was a precipitous fall in larval drug concentrations associated with pupariation. At day 11 ranges of drug concentrations (microgram/g) were: amitriptyline, < 0.01-0.01; temazepam, 0.01-0.08; trazodone, < 0.01-0.01; and trimipramine, 0.04-0.04. Day 16 pupae had corresponding ranges (microgram/g) of < 0.01, 0.01-0.01, < 0.01 and < 0.01-0.02. Transfer to drug-free food at day 5 led to similar falls in drug concentrations (microgram/g) from day 5 to day 6: 0.08-0.03 for amitriptyline, 0.61-0.09 for temazepam, 0.13-0.01 for trazodone, and 0.30-0.02 for trimipramine. The results show considerable variation in larval drug concentrations, both at the same developmental stage and at different stages of the life cycle, under conditions which closely reflect case situations. In practice, the precipitous decrease in drug concentrations in non-feeding larvae and at pupariation make it desirable to sample only larvae actively feeding on a corpse.

Modulation of the AMPA receptor by phospholipase A2: effect of the antidepressant trimipramine.

Previous results have shown that chronic administration of the antidepressant trimipramine prevents the formation of long-term potentiation in the rat hippocampus. In the present study, we compared the effects of chronic administration of trimipramine on the binding properties of hippocampal glutamate receptors and on the modulation of the DL-alpha-amino-3-hydroxy-5- methyl-isoxazolpropionic acid (AMPA) receptors by phospholipase A2 (PLA2). Whereas the binding characteristics of various agonist and antagonist ligands to the N-methyl-D-aspartate and the AMPA receptors were not modified by trimipramine treatment, there was a significant reduction in the increase in 3H-AMPA binding elicited by PLA2 treatment. Since activation of PLA2 has been reported to play a critical role in the formation of long-term potentiation, possibly mediated through a modification of the AMPA receptors, the results strengthen the hypothesis that PLA2-induced modification of 3H-AMPA binding is an important component of synaptic plasticity.

Determination of trimipramine and its demethylated and hydroxylated metabolites in plasma by gas chromatography-mass spectrometry.

A gas chromatographic-mass spectrometric (GC-MS) method has been developed, for the determination of trimipramine (TRI), desmethyltrimipramine (DTRI), didesmethyltrimipramine (DDTRI), 2-hydroxytrimipramine (2-OH-TRI) and 2-hydroxydesmethyltrimipramine (2-OH-DTRI). The method includes two derivatization steps with trifluoroacetic acid anhydride and N-methyl-N-(tert.-butyldimethyl silyl)trifluoroacetamide and the use of an SE-54 capillary silica column. The limits of quantitation were found to be 2 ng/ml for DTRI and 4 ng/ml for all other substances. Besides, methods have been optimized for the hydrolysis of the glucuronic acid conjugated metabolites. This specific detection method is useful, as polymedication is a usual practice in clinical situations, and its sensitivity allows its use for single-dose pharmacokinetic studies.

[Comparative study of the pharmacokinetics of amitriptyline oxide and trimipramine after single administration in healthy male probands and patients with renal failure]. / Vergleichende Untersuchung zur Pharmakokinetik von Amitriptylinoxid und Trimipramin nach Einmalgabe bei gesunden männlichen Probanden und Patienten mit Niereninsuffizienz.

The pharmacokinetics of the antidepressants amitriptyline oxide and trimipramine and their major metabolites amitriptyline, nor-triptyline and desmethyltrimipramine, were studied in twelve healthy male subjects (aged from 22 to 62 years) and twelve patients (aged from 25 to 73 years) with severe renal impairment (glomerular filtration rate < 10 ml/min). Oral single doses of 60 mg amitriptyline oxide and 50 mg trimipramine, separated by a washout period, were administered to all study participants. Blood and urine samples were collected up to 120 hours after administration. For trimipramine and desmethyltrimipramine, a new HPLC method was developed. The "Fischer Somatic and Undesired Effects Check List" was used for the assessment of adverse events. The mean plasma half-life and AUC of amitriptyline oxide and its metabolites were significantly higher in patients than in healthy adults. For trimipramine the AUC was significantly higher in patients. The plasma half-life of trimipramine was longer in patients, but statistically not significant. The maximum plasma concentrations for both drugs and metabolites were at an average distinctly higher in patients. Clearance rate of amitroptylinoxide and trimipramine also differed between the two groups. Correlating with these results a high incidence and a longer persistence (in most cases > 12 hours) and more pronounced adverse effects were noted in the patient group, whereas in volunteers adverse events were only observed up to approximately eight hours.

Post-mortem toxico-kinetics of trazodone.

Trazodone is a structurally unique bicyclic anti-depressant, said to be significantly less toxic than other anti-depressants following an acute overdose. We studied the tissue distribution and post-mortem redistribution of trazodone in two fatalities, one of which allowed comparison with trimipramine, a typical tricyclic anti-depressant. Case 1, a 53-year-old female weighing 72 kg, had femoral vein concentrations of trimipramine 5.5 micrograms/ml, trazodone 14.4 micrograms/ml and alcohol 107 mg%. Case 2, a 48-year-old female of 70 kg, had a femoral vein trazodone of 15.5 micrograms/ml and alcohol 34 mg%, with no other drugs detected. For case 1 and case 2 respectively, trazodone tissue concentrations were: skeletal muscle 7.3 and 9.0 micrograms/g; left and right lungs 13.3, 12.9 and 35.3, 40.1; myocardium, 30.9 and 28.9; kidneys 34.7 and 39.6; liver 73.7 and 82.4; fat 18.5 and 16.5; brain 48.6 and 20.9. For case 1 and 2, respectively, blood trazodone concentrations in 10 initial autopsy samples ranged from 13.7-17.3 and 14.4-16.9 micrograms/ml. Twenty-four and forty-eight hours later the respective ranges were 12.8-18.0 and 12.4-19.9 for case 1, 12.5-20.1 and 12.7-27.0 for case 2. By contrast, for trimipramine, blood concentrations at 0 time, 24 h and 48 hours ranged from 5.5-11.4, 5.2-14.3, and 4.2-18.2, respectively. We conclude that trazodone shows little preferential concentration in solid organs and consequently has relatively stable post-mortem blood concentrations with little drug redistribution artefact. Both the clinical pharmacokinetics and post-mortem toxicokinetics of trazodone differ significantly from the tricyclic anti-depressants.

[Suicide with chloroquine combined with maprotiline and trimipramine]. / Suizid mit Chloroquin unter Beteiligung von Maprotilin und Trimipramin.

Report on suicide with chloroquine in combination with maprotiline and trimipramine. Chloroquine and his metabolite monodesethylchloroquine could be determined in organs and body fluids. The highest organ-concentrations of chloroquine were found in liver and kidney. The survival time and dose are discussed.

Influence of quinidine on the pharmacokinetics of trimipramine and on its effect on the waking EEG of healthy volunteers. A pilot study on two subjects.

The pharmacokinetics and pharmacodynamics (waking EEG) of 75 mg trimipramine taken orally were determined in two healthy volunteers on two separate occasions, once without and once after comedication with 2 x 50 mg quinidine. Quinidine, a potent cytochrome P-450IID6 inhibitor, is used as a pharmacological tool to mimic a lack of this enzyme in man. In this study, it markedly altered the pharmacokinetics of trimipramine, almost doubling its plasma half-life and decreasing its apparent clearance and volume of distribution. These results strongly suggest that trimipramine is a substrate of cytochrome P-450IID6. These modifications of trimipramine metabolism were accompanied by measurable changes in some EEG variables, most notably with regard to the relative power in the alpha and theta bands, which showed higher and longer-lasting effects of trimipramine. Since cytochrome P-450IID6 is deficient in 5-10% of Caucasian subjects, this may have consequences in trimipramine-treated subjects, especially with regard to the effects of the drug on the EEG.

Effect of iprindole on the metabolism of trimipramine in the rat.

Major metabolites of trimipramine in young male Sprague-Dawley rats are the result of alicyclic and aromatic ring oxidation. The four major urinary metabolites have been identified as 10-oxotrimipramine, 2-hydroxytrimipramine, 2-hydroxynortrimipramine, and 2-hydroxy-10-oxotrimipramine. When iprindole was administered to rats prior to trimipramine, the effect on trimipramine metabolism was profound. The formation of both 10-oxo metabolites was virtually completely inhibited; the production of 2-hydroxytrimipramine was significantly reduced while the metabolic formation of 2-hydroxynortrimipramine was increased. It is apparent from these preliminary results that metabolic alicyclic and aromatic hydroxylations are catalyzed by different cytochrome P450 isozymes and more than one P450 isozyme is involved in the aromatic ring oxidation of trimipramine and nortrimipramine.

Simultaneous determination of trimipramine and its major metabolites by high-performance liquid chromatography.

Trimipramine is a tricyclic antidepressant drug often assayed by gas chromatographic or gas chromatographic-mass spectrometry techniques. A high-performance liquid chromatographic method with electrochemical detection is described for the assay of trimipramine and its major metabolites, monodesmethyltrimipramine and 2-hydroxytrimipramine, in plasma. The method is sensitive, accurate and robust and thus suitable for routinely assaying samples following single doses of trimipramine to man. The assay was applied to plasma samples obtained following a single 50-mg dose of trimipramine to healthy volunteers.

Nonlinear kinetics of trimipramine in depressed patients.

An increase of the dose of trimipramine (TM) results in a markedly disproportionate increase of the steady-state plasma concentration of the major active metabolite desmethyltrimipramine (DMT). Ten patients receiving 75 mg/day of TM had a mean steady-state plasma concentration of 53.8 ng/ml TM and 26.3 ng/ml DMT. Ten others receiving 150 ng/ml TM had a mean concentration of 122.5 ng/ml TM and 133.8 ng/ml DMT. This is most likely due to the saturation within therapeutic dosage range of the subspecies of cytochrome P-450 responsible for hydroxylation of DMT. Available data on metabolism of tricyclic antidepressants shows that the hydroxylation of desmethylimipramine (desipramine) but not that of desmethylamitriptyline (nortriptyline) reaches saturation within therapeutic dosage range. Clinicians should take into consideration the possibility of dose-dependent kinetics when adjusting the dose of tricyclic antidepressants. This finding highlights the value of monitoring of blood levels of antidepressants.

Chronopharmacokinetic and bioequivalence studies of two formulations of trimipramine after oral administration in man.

The bioavailability of two oral formulations of trimipramine, tablets and solution, was performed in twelve healthy volunteers, in a cross-over study. Each formulation was administered in the morning after a fasted period, and in the evening after a meal, in order to evaluate the role of both administration time and food consumption on the plasma kinetic parameters, under usual therapeutic conditions. A high interindividual variability of data was found. First, the extent of bioavailability was identical for the two formulations but the rate of bioavailability seemed to be different, with the p.o. solution, being more rapidly absorbed (tmax = 1.50 h). The effect of administration time was more obvious for the solution as shown by a lower quantitative absorption as well as a delay in time to reach the maximal concentration. Regardless of formulation and administration time, the t1/2 beta was about 10 hours and the mean MRT value was 11 hours.