Physiologically Based Pharmacokinetic Modeling to Unravel the Drug-gene Interactions of Venlafaxine: Based on Activity Score-dependent Metabolism by CYP2D6 and CYP2C19 Polymorphisms

BACKGROUND

Venlafaxine (VEN) is a commonly utilized medication for alleviating depression and anxiety disorders. The presence of genetic polymorphisms gives rise to considerable variations in plasma concentrations across different phenotypes. This divergence in phenotypic responses leads to notable differences in both the efficacy and tolerance of the drug.

PURPOSE

A physiologically based pharmacokinetic (PBPK) model for VEN and its metabolite O-desmethylvenlafaxine (ODV) to predict the impact of CYP2D6 and CYP2C19 gene polymorphisms on VEN pharmacokinetics (PK).

METHODS

The parent-metabolite PBPK models for VEN and ODV were developed using PK-Sim® and MoBi®. Leveraging prior research, derived and implemented CYP2D6 and CYP2C19 activity score (AS)-dependent metabolism to simulate exposure in the drug-gene interactions (DGIs) scenarios. The model's performance was evaluated by comparing predicted and observed values of plasma concentration-time (PCT) curves and PK parameters values.

RESULTS

In the base models, 91.1%, 94.8%, and 94.6% of the predicted plasma concentrations for VEN, ODV, and VEN + ODV, respectively, fell within a twofold error range of the corresponding observed concentrations. For DGI scenarios, these values were 81.4% and 85% for VEN and ODV, respectively. Comparing CYP2D6 AS = 2 (normal metabolizers, NM) populations to AS = 0 (poor metabolizers, PM), 0.25, 0.5, 0.75, 1.0 (intermediate metabolizers, IM), 1.25, 1.5 (NM), and 3.0 (ultrarapid metabolizers, UM) populations in CYP2C19 AS = 2.0 group, the predicted DGI AUC0-96 h ratios for VEN were 3.65, 3.09, 2.60, 2.18, 1.84, 1.56, 1.34, 0.61, and for ODV, they were 0.17, 0.35, 0.51, 0.64, 0.75, 0.83, 0.90, 1.11, and the results were similar in other CYP2C19 groups. It should be noted that PK differences in CYP2C19 phenotypes were not similar across different CYP2D6 groups.

CONCLUSIONS

In clinical practice, the impact of genotyping on the in vivo disposition process of VEN should be considered to ensure the safety and efficacy of treatment.

Enantioselective analysis of venlafaxine and its active metabolites: A review on the separation methodologies

Venlafaxine (VFX) is a serotonin and norepinephrine reuptake inhibitor chiral drug used in therapy as an antidepressant in the form of a racemate consisting of R- and S-VFX. The two enantiomers of VFX exhibit different pharmacological activities: R-VFX inhibits both norepinephrine and serotonin synaptic reuptake, whereas S-VFX inhibits only the serotonin one. R- and S-VFX are metabolized in the liver to the respective R- and S-O-desmethylvenlafaxine (ODVFX), R- and S-N-desmethylvenlafaxine (NDVFX), and R- and S-N,O-didesmethylvenlafaxine (NODVFX). The pharmacological profile of ODVFX is close to that of VFX, whereas the other two chiral metabolites (NDVFX and NODVFX) have lower affinity for the receptor sites. The pharmacokinetics of the VFX enantiomers appear stereoselective, including the metabolism process. In the past 20 years, several studies describing the enantioselective analysis of R- and S-VFX in pharmaceutical formulations and its chiral metabolites in biological matrices were published. These methods encompass liquid chromatography coupled with UV detection, mass spectrometry, or tandem mass spectrometry, and capillary electrophoresis. This paper reviews the published methods used for the determination of the individual enantiomers of VFX and its chiral metabolites in different matrices.

Determination of venlafaxine and its active metabolite O-desmethylvenlafaxine in human plasma by HPLC fluorescence

Background

Therapeutic drug monitoring guides clinical individualised medication by measuring plasma concentration, which could improve the curative effect, avoid drug overdose and reduce the incidence of adverse reactions. At present, there are few reports on the clinical detection of venlafaxine and its active metabolite O-desmethylvenlafaxine. In this paper, the detection method of venlafaxine and O-desmethylvenlafaxine in blood plasma was established, which provides an effective and convenient means for guiding clinical application of medication.

Aim

To establish a method for determination of venlafaxine and its active metabolite O-desmethylvenlafaxine in human plasma by high-performance liquid chromatography with fluorescence detection.

Methods

Chromatographic separation was achieved on an Agilent Eclipse XDB-C18 Column (4.6 × 150 mm, 5 µm) with water containing sodium dihydrogen phosphate (0.05 mol/L) and acetonitrile (72:28) as the mobile phases. The following parameters were employed: flow rate 0.5 mL/min, column temperature 30°C, fluorescence excitation wavelength 276 nm and emission wavelength 598 nm.

Results

The method showed good linearity in the concentration range 10-1000 ng/mL. The regression equation for venlafaxine was R=0.0054C+0.0264, r²=0.99991. The regression equation for O-desmethylvenlafaxine was R=0.0034C+0.0272, r²=0.99969. The intraday and interday precisions (relative SD) were less than 10%, and the quantitative limit was 10 ng/mL.

Conclusion

We established a sensitive, specific and simple method for the detection of venlafaxine and O-desmethylvenlafaxine. This method fully meets the needs of clinical trials of venlafaxine and the requirements of relevant guidelines. It provided a reference for the clinical detection of venlafaxine and O-desmethylvenlafaxine plasma concentrations and pharmacokinetic study.

A novel prodrug strategy to improve the oral absorption of O-desmethylvenlafaxine

O-Desmethylvenlafaxine (desvenlafaxine, ODV) is the active metabolite of venlafaxine, with similar activity and less risk for pharmacokinetic drug interactions compared to its parent compound venlafaxine. The purpose of this study was to design a series of esters of ODV and assess their potential as ODV prodrugs with improved bioavailability and brain uptake. Seven esters were synthesized and pharmacokinetic screening was performed in rats. The monoester formed on the phenolic hydroxyl of ODV (ODVP-1, ODVP-2, ODVP-3 and ODVP-5) could be degraded to ODV in rat plasma. These four compounds confirmed as possible prodrugs were then studied to evaluated the relative bioavailability of ODV they produced in beagle dogs. ODVP-1, ODVP-2 and ODVP-3 demonstrated higher relative bioavailability of ODV. Finally, ODVP-1, ODVP-2 and ODVP-3 were studied to evaluate their brain uptake in rats. The concentration of ODV in the rat plasma, brain and hypothalamus after administration of ODVP-1, ODVP-2 or ODVP-3 was higher compared with that of ODV. The higher bioavailability, improved pharmacokineics properties and more rapid penetration and translation of ODV suggest that ODVP-1, ODVP-2 or ODVP-3 may warrant further development and application as ODV prodrugs.

Concentrations of venlafaxine and its main metabolite O-desmethylvenlafaxine during pregnancy

WHAT IS KNOWN AND OBJECTIVE

Depression during pregnancy is common and includes risks for mother and child. Pharmacokinetics of venlafaxine may be changed during pregnancy. This study aimed to describe changes in metabolic ratios and concentrations of venlafaxine and its main metabolite O-desmethylvenlafaxine during and after pregnancy.

METHODS

To study this, we used data from our study of compliance to Antidepressants During Pregnancy (the ADAP study) to investigate the course of venlafaxine and O-desmethylvenlafaxine concentrations during pregnancy and in the period post-partum.

RESULTS AND DISCUSSION

We found that the venlafaxine concentration significantly changed during pregnancy when compared to the post-partum period (P = 0·028). The median concentration of venlafaxine in the first trimester was 98·9% (54·2-292·0%), the second 100·0% (46·5-264·0%) and the third trimester 87·0% (61·5-217·2%). We did not found differences in O-desmethylvenlafaxine concentrations in the different trimesters of pregnancy compared with the post-partum period, P = 0·565. Also the ratio of O-desmethylvenlafaxine/venlafaxine concentrations increased significantly from 76·9% (range 32·8-142·0%) in the first trimester to 196·7% (range 83·3-427·6%) in the third trimester compared with the post-partum period, P = 0·004. Further, three of seven patients had concentrations below the therapeutic reference range (100-400 μg/L) in any period of pregnancy, whereas no one had subtherapeutic concentrations in the post-partum period.

WHAT IS NEW AND CONCLUSION

Venlafaxine concentrations decreases during pregnancy, and the ratio of the concentrations of O-desmethylvenlafaxine/venlafaxine increases during pregnancy. Pregnant women using venlafaxine are at risk for subtherapeutic concentrations, therefore routine monitoring of concentrations venlafaxine and O-desmethylvenlafaxine is recommendable during pregnancy.

Rapid sensitive validated UPLC-MS method for determination of venlafaxine and its metabolite in rat plasma: Application to pharmacokinetic study

A new ultra-performance liquid chromatography–electrospray ionization mass spectrometry (UPLC–MS/ESI) method for simultaneous determination of venlafaxine (VEN) and its metabolite O-desmethylvenlafaxine (ODV) in rat plasma has been developed and validated using Venlafaxine d6 as the internal standard. The compounds and internal standard were extracted from plasma by solid phase extraction. The UPLC separation of the analytes was performed on ACQUITY UPLC^® BEH Shield RP18 (1.7 µm, 100 mm×2.1 mm) column, using isocratic elution with mobile phase constituted of water (containing 2 mM ammonium acetate): acetonitrile (20:80, v/v) at a flow rate of 0.3 mL/min. All of the analytes were eluted within 1.5 min. The compounds were ionized in the electrospray ionization (ESI) ion source of the mass spectrometer, operating in multiple reaction monitoring (MRM) and positive ion mode. The precursor to product ion transitions monitored for VEN, ODV and Venlafaxine d6 were m/z 278.3→121.08, 264.2→107.1 and 284.4→121.0, respectively. The developed and validated method was used for the pharmacokinetic study of VEN in rats.

Pharmacokinetics of venlafaxine and its major metabolite o-desmethylvenlafaxine in freely moving mice using automated dosing/sampling system

OBJECTIVE

To assess the pharmacokinetics of venlafaxine (VEN) and its major metabolite o-desmethylvenlafaxine (ODV) in freely moving mice using automated dosing/infusion (ADI) and automated blood sampling (ABS) systems. In addition, concentration of VEN and its metabolite ODV were also measured in brain by microdialysis.

MATERIALS AND METHODS

Venlafaxine was administered directly via jugular vein or gastric catheterization and blood samples were collected through carotid artery. A series of samples with 10 μl of blood was collected from the mouse using ADI/ABS and analyzed with a validated LC-MS/MS system. Extracellular concentrations of VEN and ODV in brain were investigated by using microdialysis procedure.

RESULTS

The bioavailability of VEN was 11.6%. The percent AUC ratios of ODV to VEN were 18% and 39% following intravenous and intragastric administration, respectively. The terminal half-life of venlafaxine was about two hours. Extracellular concentration of VEN contributed 3.4% of the blood amount, while ODV was not detected in dialysate.

CONCLUSION

This study suggests that besides rapid absorption of VEN, the first-pass metabolism is likely to contribute for its lower bioavailability in the mouse. The proposed automated technique can be used easily to conduct pharmacokinetic studies and is applicable to high-throughput manner in mouse model.

Desvenlafaxine in the treatment of major depressive disorder

Major depressive disorder (MDD) is among the most incapacitating conditions in the world. The emergence of the selective serotonin reuptake inhibitor (SSRI) and serotonin norepinephrine reuptake inhibitors (SNRI) antidepressants has improved the treatment of MDD. Desvenlafaxine succinate (DVS) is the succinate salt of the isolated major active metabolite of venlafaxine, O-desmethylvenlafaxine: it is the third SNRI to become available in the United States, and was approved in 2008 by the US Food and Drug Administration (FDA) for the treatment of MDD. Early investigations showed therapeutic efficacy for doses between 50 and 400 mg/day; however in doses above 100 mg/day there were incremental increases in side effects. Nausea was the most frequent adverse effect. Hence the recommended dosing for DVS is in the 50 to 100 mg range. Desvenlafaxine is excreted in urine, it is minimally metabolized via the CYP450 pathway, and is a weak inhibitor of CYP2D6. A reduced risk for pharmacokinetic drug interactions is a potential advantage over other SNRI. Further head-to-head trials involving comparisons of DVS in the 50 to 100 mg dose range with currently available SSRI and SNRI antidepressants are required. Evidence for relapse prevention is available in the 200 to 400 mg dose range, but this needs to be demonstrated in the 50 to 100 mg dose range, as well as health economic measures and quality of life evaluations.