Population pharmacokinetics of clomipramine, desmethylclomipramine, and hydroxylated metabolites in patients with depression receiving chronic treatment: model evaluation

HiPSC-derived multi-organoids-on-chip system for safety assessment of antidepressant drugs

The poor predictive power of existing preclinical models has spurred efforts to develop human-relevant models for accurate assessment of drug safety. In this work, we developed a multi-organoids-on-a-chip system derived from human induced pluripotent stem cells (hiPSCs), which allows for the assessment of the cardiac safety of an antidepressant drug, following liver metabolism in vitro. This liver-heart organoids-on-chip device contains compartmentalized chambers separated by a porous membrane, which permits the co-culture of 3D human liver organoids in the upper multi-well chamber and cardiac organoids in the bottom micropillar array simultaneously. The co-cultured liver and heart organoids on chip maintained good viability and human organ-specific functions respectively, including the synthesis of albumin and urea of liver organoids, and the beating function of cardiac organoids. In particular, the liver organoids displayed proper metabolic capabilities with high expression of CYP450 enzyme genes. Clomipramine, a widely used antidepressant drug, can be metabolized into an active metabolite (desmethylclomipramine) through the hepatic CYP450 enzymes of liver organoids on chip identified by mass spectrometry. After exposure to 1 μM clomipramine in the liver chamber for 24 h and 48 h, the co-cultured heart organoids in the bottom layer showed significantly reduced cell viability, impaired functions of cardiac beating and calcium flux, indicating the hepatic metabolism-dependent cardiotoxicity induced by clomipramine. By combining stem cell biology and microengineered technology, this proposed hiPSC-derived multi-organoids-on-a-chip system can reflect human organ-specific functions, as well as the complex process of drug metabolism and responses at the multi-organ level. It may provide a novel platform for the assessment of drug effectiveness and safety in vitro.

In Vitro and In Vivo Pipeline for Validation of Disease-Modifying Effects of Systems Biology-Derived Network Treatments for Traumatic Brain Injury-Lessons Learned

We developed a pipeline for the discovery of transcriptomics-derived disease-modifying therapies and used it to validate treatments in vitro and in vivo that could be repurposed for TBI treatment. Desmethylclomipramine, ionomycin, sirolimus and trimipramine, identified by in silico LINCS analysis as candidate treatments modulating the TBI-induced transcriptomics networks, were tested in neuron-BV2 microglial co-cultures, using tumour necrosis factor α as a monitoring biomarker for neuroinflammation, nitrite for nitric oxide-mediated neurotoxicity and microtubule associated protein 2-based immunostaining for neuronal survival. Based on (a) therapeutic time window in silico, (b) blood-brain barrier penetration and water solubility, (c) anti-inflammatory and neuroprotective effects in vitro (p < 0.05) and (d) target engagement of Nrf2 target genes (p < 0.05), desmethylclomipramine was validated in a lateral fluid-percussion model of TBI in rats. Despite the favourable in silico and in vitro outcomes, in vivo assessment of clomipramine, which metabolizes to desmethylclomipramine, failed to demonstrate favourable effects on motor and memory tests. In fact, clomipramine treatment worsened the composite neuroscore (p < 0.05). Weight loss (p < 0.05) and prolonged upregulation of plasma cytokines (p < 0.05) may have contributed to the worsened somatomotor outcome. Our pipeline provides a rational stepwise procedure for evaluating favourable and unfavourable effects of systems-biology discovered compounds that modulate post-TBI transcriptomics.

Large Variation in Brain Exposure of Reference CNS Drugs: a PET Study in Nonhuman Primates

BACKGROUND

Positron emission tomography microdosing of radiolabeled drugs allows for noninvasive studies of organ exposure in vivo. The aim of the present study was to examine and compare the brain exposure of 12 commercially available CNS drugs and one non-CNS drug.

METHODS

The drugs were radiolabeled with (11)C (t 1/2 = 20.4 minutes) and examined using a high resolution research tomograph. In cynomolgus monkeys, each drug was examined twice. In rhesus monkeys, a first positron emission tomography microdosing measurement was repeated after preadministration with unlabeled drug to examine potential dose-dependent effects on brain exposure. Partition coefficients between brain and plasma (KP) were calculated by dividing the AUC0-90 min for brain with that for plasma or by a compartmental analysis (VT). Unbound KP (KP u,u) was obtained by correction for the free fraction in brain and plasma.

RESULTS

After intravenous injection, the maximum radioactivity concentration (C max, %ID) in brain ranged from 0.01% to 6.2%. For 10 of the 12 CNS drugs, C max, %ID was >2%, indicating a preferential distribution to brain. A lower C max, %ID was observed for morphine, sulpiride, and verapamil. K P ranged from 0.002 (sulpiride) to 68 (sertraline) and 7 of 13 drugs had KP u,u close to unity. For morphine, sulpiride, and verapamil, K P u,u was <0.3, indicating impaired diffusion and/or active efflux. Brain exposure at microdosing agreed with pharmacological dosing conditions for the investigated drugs.

CONCLUSIONS

This study represents the largest positron emission tomography study on brain exposure of commercially available CNS drugs in nonhuman primates and may guide interpretation of positron emission tomography microdosing data for novel drug candidates.

Clinical and genetic correlates of suicidal ideation during antidepressant treatment in a depressed outpatient sample

AIMS

This study investigated clinical and genetic predictors of increasing suicidal ideation during antidepressant treatment.

MATERIALS & METHODS

A total of 131 depressed outpatients were allocated to four antidepressants (paroxetine, venlafaxine, clomipramine or nefazodone) in a sequential step procedure until remission. Suicidality was assessed using the 10th item of the Montgomery-Asberg Depression Rating Scale (MADRS). A total of 11 candidate genes involved in different mechanisms of antidepressant action were selected for association with increasing suicidality.

RESULTS

Increasing suicidality correlated with depression severity and higher antidepressant blood levels. Risk of increasing suicidal ideation was higher in subjects taking antidepressants other than paroxetine (odds ratio: 1.11). The strongest genetic predictor was found to be rs1360780 within the FKBP5 gene (p = 2.9 × 10(-5)), followed by 2677G>T in the ABCB1 gene. The rs130058 SNP within the 5-HTR1B gene demonstrated a differential association with increasing suicidal ideation depending on antidepressant type.

CONCLUSION

Increasing suicidal ideation might be an adverse effect of antidepressants. The involvement of FKBP5 indicates that dysregulation of the hypothalamic-pituitary-adrenal axis is involved in treatment increasing suicidal ideation.

Therapeutic drug monitoring of clomipramine and amitriptyline in a depressed patient with upper digestive tract resection

We describe a 55-year-old woman with extensive digestive resection and recurrent depressive disorder resistant to oral clomipramine tablets but not to an oral solution of amitriptyline. In the light of this case report, the potential mechanisms of drug resistance after digestive resection are discussed, including the importance of drug monitoring.

Pharmacokinetics of clomipramine, an antidepressant, in poloxamer 407-induced hyperlipidaemic model rats

Objective

This study was undertaken to investigate the effects of hyperlipidaemia on the pharmacokinetics of clomipramine, an antidepressant, particularly addressing the change of clomipramine distribution to plasma components in poloxamer 407-induced hyperlipidaemia model rats.

Methods

Clomipramine pharmacokinetic studies in hyperlipidaemic rats were performed with clomipramine continuous infusion. Furthermore, clomipramine protein binding and distribution to the brain and plasma components such as lipoproteins were investigated.

Key findings

Mean plasma concentration of clomipramine at steady state during continuous infusion (17.5 µg/min/kg) in hyperlipidaemic rats (0.45 ± 0.01 µg/ml) was significantly higher than that in the control rats (0.30 ± 0.02 µg/ml). However, the amount of clomipramine in the brain in hyperlipidaemic rats (0.31 ± 0.06 µg/g) was dramatically lower than in the control rats (1.89 ± 0.13 µg/g). However, the plasma unbound fraction in hyperlipidaemic rats (0.98 ± 0.05%) was significantly lower than that of the control rats (6.51 ± 0.62%).

Conclusions

Lower distribution to the brain and lower plasma clearance of clomipramine in hyperlipidaemic rats resulted from lower plasma unbound fraction because of higher lipid-rich protein contents in blood. Results of this study provide useful information for dosage adjustment of clomipramine in hyperlipidaemia.

Effects of physiological covariables on pharmacokinetic parameters of clomipramine in a large population of cats after a single oral administration

This study was conducted to confirm an interindividual variability in pharmacokinetic parameters of clomipramine in a large population of cats and to identify potential covariables that would explain the presence of such pharmacokinetic variability after a single dose of Clomicalm. Clomipramine hydrochloride was administered orally according to a weight-dose chart from 0.32 to 0.61 mg/kg, to 76 cats and five blood samples were then taken by direct venipuncture at 1, 3, 6, 12, and 24 h. Plasma concentrations of clomipramine and desmethylclomipramine (DCMP) were measured by LC-MS/MS. The Standard Two-Stage technique was used to assess differences and detect correlations between pharmacokinetic parameter estimates and individual covariables. A large interindividual variability in all pharmacokinetic parameters (CV% 64-124) was detected. Statistically significant gender-related differences were detected in MR and Cl/F, where female cats had a higher mean MR (0.53) and faster Cl/F (0.36 L/h.kg) than males (0.36 and 0.21 L/h.kg, respectively). No correlation could be found between clomipramine AUC0-24 h or DCMP AUC0-24 h and sedation scores. Further feline studies are required to assess these findings after multiple dosing of clomipramine and DCMP to allow clinical extrapolation.

Pharmacokinetics of clomipramine and desmethylclomipramine after single-dose intravenous and oral administrations in cats

A cross-over study was performed in six adult spayed cats to determine the pharmacokinetics of clomipramine and its metabolite, desmethylclomipramine (DCMP) after intravenous (0.25 mg/kg) and oral (0.5 mg/kg) single-dose administrations. Plasma clomipramine and DCMP were measured by high-performance liquid chromatography at regular intervals for up to 30 h. Intravenous clomipramine best fit a two-compartmental model yielding an elimination rate constant of 0.037-0.09 h(-1) from which a mean half-life of 12.3 h was calculated. Mean clomipramine AUC(0--infinity) (ngxh/mL), clearance (L/hxkg), V(ss) (L/kg) and MRT (h) values were 652.5, 0.393, 5.0, and 13.5, respectively. Compartmental modeling for clomipramine, after oral administration, and DCMP after both administrations, produced wide parameter estimates and plots of residuals indicated poor goodness of fit. Noncompartmental analysis yielded mean AUC(0--30 h) (ngxh/mL), C(max) (ng/mL) and T(max) (h) of 948.3, 87.5 and 6.2 for clomipramine, and 613.8, 34.8, and 12.8 for DCMP respectively after oral administration. Clomipramine bioavailability was 90%. The present study showed marked pharmacokinetic variability for clomipramine and DCMP through biphasic absorption and potential genetic variability in clomipramine metabolism. It was concluded that population pharmacokinetics would allow better characterization of clomipramine variability that may explain the variability in clinical response noted in cats.

Relevance of assessing drug concentration exposure in pharmacogenetic and imaging studies

Pharmacodynamic differences are difficult to interpret without drug concentration data. In particular, variability in drug exposure may confound the interpretation of pharmacogenetic, therapeutic outcome, and neuroimaging studies. Inter-individual variability in concentrations can be quite high due to variable adherence and pharmacokinetics. For example, clearance may be influenced by genetics, drug interactions, age and illness. We review findings that acute responses to selective serotonin reuptake inhibitors can have a concentration-response relationship using positron emission tomography and neuroendocrine measures. We also present preliminary evidence that the concentration-response relationship for paroxetine is influenced by genotypic differences at the serotonin transporter promoter. In large clinical studies, the accurate assessment of drug exposure can be challenging, with several techniques used to assess exposure. Population pharmacokinetics (Pop PK) is a method that is ideally suited for analysing concentration data from large trials because both patient-specific and population parameters can be determined with only a small number of plasma samples per patient. As opposed to relying on prescribed doses or a single trough level, the ability to determine more accurately exposure with Pop PK reduces the heterogeneity introduced by exposure variability. Pop PK hierarchic Bayesian approaches have been effective for characterizing anticonvulsants, antibiotics, antineoplastics and antiarrhythmics. We have recently successfully incorporated these pop PK analyses into routine assessments of elderly patients in clinical trials of selective serotonin reuptake inhibitors (SSRIs) and second generation antipsychotics. For the design and interpretation of neuroimaging, pharmacogenetic, and behavioural studies, the assessment of drug concentration exposure is therefore feasible and has potentially important ramifications.