Multiplexed quantification of venlafaxine and metabolites in human plasma by liquid chromatography-tandem mass spectrometry

BACKGROUND

Venlafaxine (VEN) and its O-demethylated metabolite, O-desmethylvenlafaxine (ODV), are commonly prescribed serotonin-norepinephrine reuptake inhibitors, approved for the treatment of depression and anxiety. Both are metabolized to inactive metabolites via cytochrome P450 enzymes. While previous studies have focused on quantifying VEN and ODV, bioanalytical methods for the simultaneous measurement of all metabolites are needed to fully characterize the pharmacology of VEN and ODV.

METHODS

K2EDTA plasma was spiked with VEN, ODV, N-desmethylvenlafaxine (NDV), N,O-didesmethylvenlafaxine (NODDV), and N,N-didesmethylvenlafaxine (NNDDV). Drugs and metabolites were extracted via protein precipitation and quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The multiplexed assay was validated in accordance with regulatory recommendations, and evaluated in remnant plasma samples from persons prescribed venlafaxine.

RESULTS

The analytical measuring range for venlafaxine and all four metabolites was 5-800 ng/mL. Standard curves were generated via weighted quadratic (NNDDV) or linear (VEN, ODV, NDV, NODDV) regression of calibrators. Inter-assay imprecision was between 1.9-9.3% for all levels of all analytes. Minor matrix effects were observed, and both recovery efficiency and process efficiency were >96% for all analytes. All other assay validation assessments met acceptance criteria. Drug concentrations measured from remnant plasma specimens obtained from patients with current venlafaxine prescriptions (37.5-450 mg/day) yielded NDDV, NDV, and NODDV metabolite concentrations in 6/21, 14/21, and 20/21 samples, respectively. The ratio of active to inactive analytes ranged from 0.74 to 14.5, with a median of 6.39.

CONCLUSIONS

An efficient and accurate LC-MS/MS method was developed and validated for the quantification of VEN, ODV, and all three inactive metabolites in plasma. The assay met all acceptance criteria, and may be used in future studies of the pharmacokinetics of these drugs.

CYP2D6 Phenotype Influences Pharmacokinetic Parameters of Venlafaxine: Results from a Population Pharmacokinetic Model in Older Adults with Depression

In this study, we aimed to improve upon a published population pharmacokinetic (PK) model for venlafaxine (VEN) in the treatment of depression in older adults, then investigate whether CYP2D6 metabolizer status affected model-estimated PK parameters of VEN and its active metabolite O-desmethylvenlafaxine. The model included 325 participants from a clinical trial in which older adults with depression were treated with open-label VEN (maximum 300 mg/day) for 12 weeks and plasma levels of VEN and O-desmethylvenlafaxine were assessed at weeks 4 and 12. We fitted a nonlinear mixed-effect PK model using NONMEM to estimate PK parameters for VEN and O-desmethylvenlafaxine adjusted for CYP2D6 metabolizer status and age. At both lower doses (up to 150 mg/day) and higher doses (up to 300 mg/day), CYP2D6 metabolizers impacted PK model-estimated VEN clearance, VEN exposure, and active moiety (VEN + O-desmethylvenlafaxine) exposure. Specifically, compared with CYP2D6 normal metabolizers, (i) CYP2D6 ultra-rapid metabolizers had higher VEN clearance; (ii) CYP2D6 intermediate metabolizers had lower VEN clearance; (iii) CYP2D6 poor metabolizers had lower VEN clearance, higher VEN exposure, and higher active moiety exposure. Overall, our study showed that including a pharmacogenetic factor in a population PK model could increase model fit, and this improved model demonstrated how CYP2D6 metabolizer status affected VEN-related PK parameters, highlighting the importance of genetic factors in personalized medicine.

Novel radioiodinated desvenlafaxine-loaded lipid nanocapsule for brain delivery

Lipid nanocapsules (LNCs) are lipid nanocarriers developed for drug delivery enhancement. The antidepressant drug desvenlafaxine (DSV) was entrapped in LNC to improve its brain delivery. Different DSV-loaded LNCs formulae using different oils and surfactants were studied to obtain the optimum formula for further studies. In vivo biodistribution studies were done using Swiss albino mice by intravenous injection of DSV-loaded LNCs by radioiodination technique. The optimum DSV-loaded LNC formula was obtained by using Labrafil® M1944CS as the oil and Solutol® HS15 as the surfactant in the ratio of 1:1, with a particle size of 34.28 ± 0.41 nm, a polydispersity index of 0.032 ± 0.05, a zeta potential of -25.77 ± 1.41, and good stability for up to 6 months. The in vivo biodistribution and pharmacokinetics data ensure the bioavailability improvement for DSV brain delivery as Cmax and AUC(1-t) increased more than double for intravenously DSV-loaded LNCs compared with the DSV solution. In conclusion, the results obtained from this study give an insight into the great potential of using DSV-loaded LNC for the enhancement of brain delivery.

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.

A Massive Venlafaxine Intoxication: Evolution of Cardiac Toxicity with Venlafaxine and O-Desmethylvenlafaxine Elimination Kinetics: A Grand Round

BACKGROUND

This study presents the case of a 19-year-old woman who attempted suicide by ingesting 11.25 g of venlafaxine (V). She was admitted to the hospital with severe biventricular dysfunction, progressing to cardiac arrest requiring extracorporeal circulatory life support for 11 days. The pharmacokinetics of venlafaxine during impaired cardiac output and the effect of its active metabolite, the O-desmethylvenlafaxine (ODV), are currently not very well understood.

METHODS AND RESULTS

Serum concentrations of V and ODV were monitored twice daily for 3 weeks. The maximum concentrations of venlafaxine and ODV were at 14 hours after ingestion, with 29,180 mcg/L for V and 5399 mcg/L for ODV. Half-lives increased, requiring 2 weeks to eliminate the drug. The left ventricular ejection fraction significantly improved when V + ODV was below 1000 mcg/L and remained altered until the ODV concentrations were lower than 400 mcg/L.

CONCLUSIONS

This report, with complete elimination kinetic of V and ODV in a monodrug intoxication, provides information about the modification of pharmacokinetics in the case of an overdose managed by extracorporeal circulatory life support, the cardiac toxicity of ODV, and the value of the toxic threshold for the active moiety.

Effectiveness of Antidepressants in Combination with Psychotherapy

BACKGROUND

Consensus-guidelines for prescribing antidepressants recommend that clinicians should be vigilant to match antidepressants to patient's medical history but provide no specific advice on which antidepressant is best for a given medical history.

AIMS OF THE STUDY

For patients with major depression who are in psychotherapy, this study provides an empirically derived guideline for prescribing antidepressant medications that fit patients' medical history.

METHODS

This retrospective, observational, cohort study analyzed a large insurance database of 3,678,082 patients. Data was obtained from healthcare providers in the U.S. between January 1, 2001, and December 31, 2018. These patients had 10,221,145 episodes of antidepressant treatments. This study reports the remission rates for the 14 most commonly prescribed single antidepressants (amitriptyline, bupropion, citalopram, desvenlafaxine, doxepin, duloxetine, escitalopram, fluoxetine, mirtazapine, nortriptyline, paroxetine, sertraline, trazodone, and venlafaxine) and a category named "Other" (other antidepressants/combination of antidepressants). The study used robust LASSO regressions to identify factors that affected remission rate and clinicians' selection of antidepressants. The selection bias in observational data was removed through stratification. We organized the data into 16,770 subgroups, of at least 100 cases, using the combination of the largest factors that affected remission and selection bias. This paper reports on 2,467 subgroups of patients who had received psychotherapy.

RESULTS

We found large, and statistically significant, differences in remission rates within subgroups of patients. Remission rates for sertraline ranged from 4.5% to 77.86%, for fluoxetine from 2.86% to 77.78%, for venlafaxine from 5.07% to 76.44%, for bupropion from 0.5% to 64.63%, for desvenlafaxine from 1.59% to 75%, for duloxetine from 3.77% to 75%, for paroxetine from 6.48% to 68.79%, for escitalopram from 1.85% to 65%, and for citalopram from 4.67% to 76.23%. Clearly these medications are ideal for patients in some subgroups but not others. If patients are matched to the subgroups, clinicians can prescribe the medication that works best in the subgroup. Some medications (amitriptyline, doxepin, nortriptyline, and trazodone) always had remission rates below 11% and therefore were not suitable as single antidepressant therapy for any of the subgroups.

DISCUSSIONS

This study provides an opportunity for clinicians to identify an optimal antidepressant for their patients, before they engage in repeated trials of antidepressants.

IMPLICATIONS FOR HEALTH CARE PROVISION AND USE

To facilitate the matching of patients to the most effective antidepressants, this study provides access to a free, non-commercial, decision aid at http://MeAgainMeds.com.

IMPLICATIONS FOR HEALTH POLICIES

 Policymakers should evaluate how study findings can be made available through fragmented electronic health records at point-of-care. Alternatively, policymakers can put in place an AI system that recommends antidepressants to patients online, at home, and encourages them to bring the recommendation to their clinicians at their next visit.

IMPLICATIONS FOR FURTHER RESEARCH

 Future research could investigate (i) the effectiveness of our recommendations in changing clinical practice, (ii) increasing remission of depression symptoms, and (iii) reducing cost of care. These studies need to be prospective but pragmatic. It is unlikely random clinical trials can address the large number of factors that affect remission.

The Pharmacokinetics and Bioequivalence of Desvenlafaxine Succinate in Chinese Healthy Subjects Under Fasting and Fed States

Desvenlafaxine succinate is a selective serotonin-norepinephrine reuptake inhibitor for the treatment of major depressive disorder. The pharmacokinetic profile of desvenlafaxine succinate at the clinically recommended dose of 50 mg in Chinese healthy subjects has been reported rarely. The objective of this study was to evaluate the pharmacokinetics and bioequivalence of desvenlafaxine succinate in Chinese healthy subjects. A single-dose, open-label, randomized, two-way crossover study with a 7-day washout period was conducted. A total of 88 individuals were incorporated to show bioequivalence of a generic and a reference drug, with 48 individuals in the fasting state and 40 receiving a high-fat diet. Finally, 46 and 38 individuals completed the fasting and the fed study, respectively. The 90% confidence intervals of the adjusted geometric mean ratios for maximum plasma concentration, area under the concentration-time curve from time zero to the last measurable concentration, and area under the concentration-time curve from time zero to infinity all fell in the bioequivalent interval of 80%-125% in both the fasting and fed states. A total of 33 adverse events were reported, and all were mild or moderate in severity. In summary, the generic and reference formulations were bioequivalent, with no observable safety differences in the fasting/fed state.

Comparison of UV and UV-LED activated sodium percarbonate for the degradation of O-desmethylvenlafaxine

As an active metabolite of venlafaxine and emerging antidepressant, O-desmethylvenlafaxine (ODVEN) was widely detected in different water bodies, which caused potential harm to human health and environmental safety. In this study, the comparative work on the ODVEN degradation by UV (254 nm) and UV-LED (275 nm) activated sodium percarbonate (SPC) systems was systematically performed. The higher removal rate of ODVEN can be achieved under UV-LED direct photolysis (14.99%) than UV direct photolysis (4.57%) due to the higher values of photolysis coefficient at the wavelength 275 nm. Significant synergistic effects were observed in the UV/SPC (80.38%) and UV-LED/SPC (53.57%) systems and the former exhibited better performance for the elimination of ODVEN. The degradation of ODVEN all followed the pseudo-first-order kinetics well in these processes, and the pseudo-first-order rate constant (k_obs) increased with increasing SPC concentration. Radicals quenching experiments demonstrated that both ·OH and CO₃·^- were involved in the degradation of ODVEN and the second-order rate constant of ODVEN with CO₃·^- (1.58 × 10⁸ (mol/L)^-1 sec^-1) was reported for the first time based on competitive kinetic method. The introduction of HA, Cl^-, NO₃^- and HCO₃^- inhibited the ODVEN degradation to varying degrees in the both processes. According to quantum chemical calculation, radical addition at the ortho-position of the phenolic hydroxyl group was confirmed to be the main reaction pathways for the oxidation of ODVEN by ·OH. In addition, the oxidation of ODVEN may involve the demethylation, H-abstraction, OH-addition and C-N bond cleavage. Eventually, the UV-LED/SPC process was considered to be more cost-effective compared to the UV/SPC process, although the UV/SPC process possessed a higher removal rate of ODVEN.

Persistence of N-oxides transformation products of tertiary amine drugs at lab and field studies

This work aimed at studying the formation and persistence of N-oxides transformation products (TPs) of tertiary amine drugs by combining laboratory and field studies relevant for surface water. A monitoring study using passive samplers was first achieved for assessing attenuation of selected pharmaceuticals and their related N-oxides and N-, O-dealkylated TPs (i.e., venlafaxine, tramadol, amisulpride and sulpiride) along a 1.7 km river stretch between two sampling sites. This study revealed the stability of tramadol-N-oxide, amisulpride-N-oxide and the fast dissipation of O-desmethylvenlafaxine-N-oxide, as well as the significance of N-oxidized TPs in comparison to N-dealkylated TPs and parent compounds in river. Lab-scale experiments were then implemented for a better understanding of their mechanisms of formation and degradation under aerobic water/sediment testing and under simulated solar photochemistry. N-oxidation reactions were always a minor transformation pathway under both degradation conditions with respect to N-and O-dealkylation reactions. The amount of generated N-oxides were similar for venlafaxine, tramadol and sulpiride and peaked in the 8.4-12.8% and <4% of their initial concentration (100 μg/L), during photodegradation and biodegradation experiments, respectively. Other transformation pathways such as hydroxylation and α-C-hydroxylation followed by oxidation to amide or dehydration were also identified. Investigated N-oxides TPs (except O-desmethylvenlafaxine-N-oxide) were found stable under solar photolysis and aerobic biodegradation with a very slight reverse reaction to parent compound observed for tramadol-N-oxide and amisulpride-N-oxide. Lab-scale degradation experiments were not able to anticipate the high occurrence levels of N-oxide compounds in the environment. This was most likely due to faster degradation kinetics and/or higher sorption to sediment of parent compounds and dealkylated TPs over N-oxide TPs, resulting in higher relative accumulation of the latter.

Measurement of Hepatic CYP3A4 and 2D6 Activity Using Radioiodine-Labeled O-Desmethylvenlafaxine

Drug metabolizing enzyme activity is affected by various factors such as drug–drug interactions, and a method to quantify drug metabolizing enzyme activity in real time is needed. In this study, we developed a novel radiopharmaceutical for quantitative imaging to estimate hepatic CYP3A4 and CYP2D6 activity. Iodine-123- and 125-labeled O-desmethylvenlafaxine (123/125I-ODV) was obtained with high labeling and purity, and its metabolism was found to strongly involve CYP3A4 and CYP2D6. SPECT imaging in normal mice showed that the administered 123I-ODV accumulated early in the liver and was excreted into the gallbladder, as evaluated by time activity curves. In its biological distribution, 125I-ODV administered to mice accumulated early in the liver, and only the metabolite of 125I-ODV was quickly excreted into the bile. In CYP3A4- and CYP2D6-inhibited model mice, the accumulation in bile decreased more than in normal mice, indicating inhibition of metabolite production. These results indicated that imaging and quantifying the accumulation of radioactive metabolites in excretory organs will aid in determining the dosages of various drugs metabolized by CYP3A4 and CYP2D6 for individualized medicine. Thus, 123/125I-ODV has the potential to direct, comprehensive detection and measurement of hepatic CYP3A4 and CYP2D6 activity by a simple and less invasive approach.

Simple and rapid quantification of cetirizine, venlafaxine, and O-desmethylvenlafaxine in human breast milk, and metformin in human milk and plasma with UHPLC-MS/MS

The majority of women have health problems that require medication after giving birth. Complications such as allergies, postpartum depression, and diabetes are often treated with drugs such as cetirizine, venlafaxine, and metformin, respectively. These treatments are considered safe during lactation, but information of the transfer of drugs to breast milk and possible effects on the infant is scarce. Therefore, this needs to be systematically investigated in larger populations. To enable the determination of drug transfer, we here describe the validation of two rapid, sensitive, and high-throughput analysis methods for 1) simultaneous quantification of cetirizine, venlafaxine, and O-desmethylvenlafaxine in human breast milk, and 2) metformin in human breast milk and plasma. In both methods, a simple protein precipitation protocol with acetonitrile and benchtop-centrifugation was used prior to compound analysis with liquid-chromatography tandem mass spectrometry. The methods had linear ranges between 0.39 - 194.5 ng/mL for cetirizine, 0.28 - 138.7 ng/mL for venlafaxine, 0.26 - 131.7 ng/mL for O-desmethylvenlafaxine, in milk, and 0.65 - 193.7 ng/mL for metformin in both milk and plasma. Intra-run and inter-run precision and accuracy were ≤ 9% for cetirizine, venlafaxine, and O-desmethylvenlafaxine in milk, and ≤ 7% for metformin in milk and plasma. Cetirizine was measured to median milk concentrations of 13 ng/mL (range: 0.65 - 65 ng/mL) in 228 donor samples from breast-feeding women.

Elucidating venlafaxine metabolism in the Mediterranean mussel (Mytilus galloprovincialis) through combined targeted and non-targeted approaches

Exposure of aquatic organisms to antidepressants is currently well documented, while little information is available on how wild organisms cope with exposure to these pharmaceutical products. Studies on antidepressant metabolism in exposed organisms could generate information on their detoxification pathways and pharmacokinetics. The goal of this study was to enhance knowledge on the metabolism of venlafaxine (VEN)-an antidepressant frequently found in aquatic ecosystems-in Mytilus galloprovincialis, a bivalve that is present worldwide. An original tissue extraction technique based on the cationic properties of VEN was developed for further analysis of VEN and its metabolites using targeted and non-targeted approaches. This extraction method was assessed in terms of recovery and matrix effects for VEN metabolites. Commercial analytical standards were applied to characterize metabolites found in mussels exposed to 10 μg/L VEN for 3 and 7 days. Targeted and non-targeted approaches using liquid chromatography (LC) combined with high-resolution mass spectrometry (HRMS) were implemented to screen for expected metabolites based on the literature on aquatic species, and for metabolites not previously documented. Four venlafaxine metabolites were identified, namely N-desmethylvenlafaxine and O-desmethylvenlafaxine, which were clearly identified using analytical standards, and two other metabolites revealed by non-target analysis. According to the signal intensity, hydroxy-venlafaxine (OH-VEN) was the predominant metabolite detected in mussels exposed for 3 and 7 days.

Effects of desvenlafaxine on blood pressure in patients treated for major depressive disorder: a pooled analysis

OBJECTIVE

To evaluate the effect of the serotonin-norepinephrine re-uptake inhibitor desvenlafaxine on blood pressure and incidence of new onset hypertension in pooled short-term studies and in two longer-term, randomized withdrawal studies.

RESEARCH DESIGN AND METHODS

Data from patients randomly assigned to desvenlafaxine 10 mg to 400 mg/day or placebo in 11 short-term (8-12 weeks), fixed-dose, double-blind, placebo-controlled studies of major depressive disorder (MDD) were pooled for analysis; two desvenlafaxine randomized withdrawal studies (36 and 46 weeks) were analyzed separately.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov , NCT00072774, NCT00073762, NCT00277823, NCT00300378, NCT00384033, NCT00798707, NCT00863798, NCT01121484, NCT00824291, NCT01432457, NCT00075257, NCT00887224.

MAIN OUTCOME MEASURES

Outcomes included change from baseline in supine systolic blood pressure (SSBP) and supine diastolic blood pressure (SDBP), assessed using a mixed model repeated measures (MMRM) analysis, and incidence of hypertension (defined as three consecutive second SDBP measures ≥90 mm Hg AND increase of ≥10 mm Hg from baseline and/or SSBP ≥140 mm Hg AND increase of ≥10 mm Hg), analyzed using Cochran Mantel Hanzael tests. Potential predictors of change in SSBP and SDBP at LOCF were examined by including predictor variables in a regression model.

RESULTS

In the pooled, short-term studies, mean changes from baseline over time in SSBP and SDBP were statistically significant compared with placebo for the desvenlafaxine doses of 10 mg/day or greater for SSBP (p ≤ 0.0004; MMRM) and 25 mg/day or greater for SDBP (p ≤ 0.0449; MMRM). The proportion of patients with new onset hypertension differed significantly from placebo for the 50, 200, and 400 mg/day doses (1.9%, 2.4%, 4.8%, respectively, vs 0.8%; all p ≤ 0.0244). Predictors of change in BP included baseline SDBP, baseline SSBP, dose, body mass index, gender, age, race, and history of hypertension.

LIMITATIONS

Data were pooled from studies which differed somewhat in study design and patient demographics. None of the studies were originally designed to examine treatment effects on BP. Study entry criteria limit generalization of these results to medically stable patients with a primary diagnosis of MDD.

CONCLUSIONS

Short-term desvenlafaxine treatment was associated with small but statistically significant increases in SSBP and SDBP.

Effect of redox conditions on pharmaceutical loss during biological wastewater treatment using sequencing batch reactors

We lack a clear understanding of how wastewater treatment plant (WWTP) process parameters, such as redox environment, impact pharmaceutical fate. WWTPs increasingly install more advanced aeration control systems to save energy and achieve better nutrient removal performance. The impact of redox condition, and specifically the use of microaerobic (low dissolved oxygen) treatment, is poorly understood. In this study, the fate of a mixture of pharmaceuticals and several of their transformation products present in the primary effluent of a local WWTP was assessed in sequencing batch reactors operated under different redox conditions: fully aerobic, anoxic/aerobic, and microaerobic (DO concentration ≈0.3mg/L). Among the pharmaceuticals that were tracked during this study (atenolol, trimethoprim, sulfamethoxazole, desvenlafaxine, venlafaxine, and phenytoin), overall loss varied between them and between redox environments. Losses of atenolol and trimethoprim were highest in the aerobic reactor; sulfamethoxazole loss was highest in the microaerobic reactors; and phenytoin was recalcitrant in all reactors. Transformation products of sulfamethoxazole and desvenlafaxine resulted in the reformation of their parent compounds during treatment. The results suggest that transformation products must be accounted for when assessing removal efficiencies and that redox environment influences the degree of pharmaceutical loss.

Relative efficacy and tolerability of vortioxetine versus selected antidepressants by indirect comparisons of similar clinical studies

INTRODUCTION

Vortioxetine is an antidepressant with multimodal activity which has shown efficacy in major depressive disorder (MDD) patients in six of ten short-term, randomized, placebo-controlled trials (completed end 2012).

METHODS

We performed meta-regression analyses to indirectly compare vortioxetine to seven marketed antidepressants with different mechanisms of action. To ensure study comparability, only experimental drug and placebo arms from placebo-controlled registration studies were included in primary analyses. The main outcomes were efficacy (standardized mean difference in change from baseline to 2 months on primary endpoint [MADRS/HAM-D]), and tolerability (withdrawal rate due to adverse events).

RESULTS

For efficacy, estimates of treatment effect (negative estimates favor vortioxetine) for vortioxetine versus comparators were: agomelatine, -0.16 (p = 0.11); desvenlafaxine, 0.03 (p = 0.80); duloxetine, 0.09 (p = 0.42); escitalopram, -0.05 (p = 0.70); sertraline, -0.04 (p = 0.83); venlafaxine IR/XR, 0.12 (p = 0.33); and vilazodone, -0.25 (p = 0.11). For tolerability, all but one combination was numerically in favor of vortioxetine (odds ratio < 1), although not all differences were statistically significant: agomelatine, 1.77 (p = 0.03); desvenlafaxine, 0.58 (p = 0.04); duloxetine, 0.75 (p = 0.26); escitalopram, 0.67 (p = 0.28); sertraline, 0.30 (p = 0.01); venlafaxine, 0.47 (p = 0.01); and vilazodone, 0.64 (p = 0.18). Sensitivity analyses did not significantly alter antidepressant effect estimates or relative ranking.

CONCLUSION

These meta-regression data show that vortioxetine offers a comparable or favorable combination of efficacy (measured by MADRS/HAM-D) and tolerability (measured by withdrawal rate due to adverse events) versus other antidepressants in registration studies in MDD. Alternative methods like mixed-treatment comparison and inclusion of all randomized studies and active reference arms may provide complementary information to this analysis (more evidence but also more heterogeneity). Key messages: Indirect comparisons based on registration studies allow a useful comparison between a recently approved antidepressant and an approved drug. Vortioxetine offers a comparable or favorable combination of efficacy (measured by MADRS/HAM-D assessments) and tolerability (measured by withdrawal rate due to adverse events) versus other antidepressants in registration studies in MDD.

Is desvenlafaxine effective and safe in the treatment of menopausal vasomotor symptoms? A meta-analysis and meta-regression of randomized double-blind controlled studies

BACKGROUND

During perimenopause, vasomotor symptoms are known to have a detrimental effect on women's functional ability and quality of life. For symptomatic women not eligible for hormonal therapy, desvenlafaxine is an option, but its safety margin and tolerability are not yet determined.

METHODS

A computer-based literature search was done in the databases of MEDLINE, Cochrane library, and HINARI (Health InterNetwork Access to Research Initiative). Meta-analysis was conducted by including double-blind randomized controlled studies on the effectiveness and safety of desvenlafaxine in the treatment of hot flashes. The effectiveness, safety and tolerability of desvenlafaxine were determined by standardized mean differences (SMDs) and Mantel-Haenszel odds ratio. Subgroup analysis based on doses of desvenlafaxine and linear meta-regression analyses were performed for several covariates. Heterogeneity testing, the risk of bias assessment and sensitivity analyses were done.

RESULTS

Desvenlafaxine was associated with a statistically significant reduction in the number and severity of daily moderate to severe hot flashes. The number of nighttime awakenings because of hot flashes was also significantly decreased. However, the rate of desvenlafaxine treatment discontinuation because of adverse events was a significantly higher than placebo treated women and the risk ratios of adverse events like asthenia, hypertension, anorexia, constipation, diarrhea, dry mouth, nausea, dizziness, insomnia, somnolence and mydriasis were very high.

CONCLUSION

Desvenlafaxine is effective in the treatment of hot flashes but it is strongly associated with several adverse events and treatment discontinuation. Further clinical trials focusing only on desvenlafaxine related adverse events are highly warranted before it is approved for public use.

Desvenlafaxine may accelerate neuronal maturation in the dentate gyri of adult male rats

Adult hippocampal neurogenesis has been linked to the effects of anti-depressant drugs on behavior in rodent models of depression. To explore this link further, we tested whether the serotonin-norepinephrine reuptake inhibitor (SNRI) venlafaxine impacted adult hippocampal neurogenesis differently than its primary active SNRI metabolite desvenlafaxine. Adult male Long Evans rats (n = 5-6 per group) were fed vehicle, venlafaxine (0.5 or 5 mg) or desvenlafaxine (0.5 or 5 mg) twice daily for 16 days. Beginning the third day of drug treatment, the rats were given a daily bromodeoxyuridine (BrdU; 50 mg/kg) injection for 5 days to label dividing cells and then perfused 2 weeks after the first BrdU injection to confirm total new hippocampal cell numbers and their phenotypes. The high desvenlafaxine dose increased total new BrdU+ cell number and appeared to accelerate neuronal maturation because fewer BrdU+ cells expressed maturing neuronal phenotypes and more expressed mature neuronal phenotypes in the dentate gyri of these versus vehicle-treated rats. While net neurogenesis was not increased in the dentate gyri of rats treated with the high desvenlafaxine dose, significantly more mature neurons were detected. Our data expand the body of literature showing that antidepressants impact adult neurogenesis by stimulating NPC proliferation and perhaps the survival of neuronal progeny and by showing that a high dose of the SNRI antidepressant desvenlafaxine, but neither a high nor low venlafaxine dose, may also accelerate neuronal maturation in the adult rat hippocampus. These data support the hypothesis that hippocampal neurogenesis may indeed serve as a biomarker of depression and the effects of antidepressant treatment, and may be informative for developing novel fast-acting antidepressant strategies.

Phenolic esters of O-desmethylvenlafaxine with improved oral bioavailability and brain uptake

O-Desmethylvenlafaxine (desvenlafaxine, ODV) is a recently approved antidepressant which in some clinical studies failed to meet a satisfactory end-point. The aim of this study was to prepare a series of phenolic esters of ODV and evaluate their potential as ODV prodrugs with improved brain uptake. Fifteen phenolic esters (compounds 1a-o) were synthesized and their pharmacokinetic profiles evaluated in rat. The four compounds producing the highest relative bioavailability of ODV in rat (compounds 1c, 1e, 1n, 1o) were then studied to evaluate their brain uptake. Of these four compounds, compound 1n (the piperonylic acid ester of ODV) demonstrated the highest C(max) of ODV both in the rat hypothalamus and total brain. Finally the pharmacokinetics of 1n were evaluated in beagle dog where the increase in relative bioavailability of ODV was found to be as great as in rat. This high relative bioavailability of ODV coupled with its good brain penetration make 1n the most promising candidate for development as an ODV prodrug.

[Extraction techniques for analysis of venlafaxine and its metabolites in biological matrices]

Venlafaxine (VEN), which was introduced into therapy in 1990s is one of the most often used antidepressants. The monitoring of its concentration in the organism is recommended, particularly in the case when a patient suffers of others illnesses and is treated with different drugs, which can interfere with VEN. The most popular diagnostic material for the determination of VEN level is blood. The present study is the review of actual reports on the methods of extraction of VEN and its metabolite from blood and other human diagnostic materials, like saliva and urine, and also from animals tissues. The paper shows the classic extraction methods, such as liquid-liquid extraction and solid-phase extraction. It also contains the modifications of these methods such as liquid-phase microextraction and cloud point extraction. According to the literature it can be stated that the best recovery of VEN and its main metabolite, O-demethylvenlafaxine, was obtained when the liquid-liquid extraction was used. The new, modified methods of extraction, are cost-effective, owing to the reduced use of solvents and also smaller volume of diagnostic material, but the results of the analysis, especially the recovery of the analytes, were lower than those obtained by classic methods of extraction.

Degradation of lidocaine, tramadol, venlafaxine and the metabolites O-desmethyltramadol and O-desmethylvenlafaxine in surface waters

The photodegradation and biotic transformation of the pharmaceuticals lidocaine (LDC), tramadol (TRA) and venlafaxine (VEN), and of the metabolites O-desmethyltramadol (ODT) and O-desmethylvenlafaxine (ODV) in the aquatic environmental have been investigated. Photodegradation experiments were carried out using a medium pressure Hg lamp (laboratory experiments) and natural sunlight (field experiments). Degradation of the target compounds followed a first-order kinetic model. Rates of direct photodegradation (light absorption by the compounds itself) at pH 6.9 were very low for all of the target analytes (≤0.0059 h(-1) using a Hg lamp and ≤0.0027 h(-1) using natural sunlight), while rates of indirect photodegradation (degradation of the compounds through photosensitizers) in river water at pH 7.5 were approximately 59 (LDC), 5 (TRA), 8 (VEN), 15 (ODT) and 13 times (ODV) higher than the rates obtained from the experiments in ultrapure water. The accelerated photodegradation of the target compounds in natural water is attributed mainly to the formation of hydroxyl radicals through photochemical reactions. Biotic (microbial) degradation of the target compounds in surface water has been shown to occur at very low rates (≤0.00029 h(-1)). The half-life times determined from the field experiments were 31 (LDC), 73 (TRA), 51 (VEN), 21 (ODT) and 18h (ODV) considering all possible mechanisms of degradation for the target compounds in river water (direct photodegradation, indirect photodegradation and biotic degradation).

Medical school gift restriction policies and physician prescribing of newly marketed psychotropic medications: difference-in-differences analysis

OBJECTIVE

To examine the effect of attending a medical school with an active policy on restricting gifts from representatives of pharmaceutical and device industries on subsequent prescribing behavior.

DESIGN

Difference-in-differences approach.

SETTING

14 US medical schools with an active gift restriction policy in place by 2004.

PARTICIPANTS

Prescribing patterns in 2008 and 2009 of physicians attending one of the schools compared with physicians graduating from the same schools before the implementation of the policy, as well as a set of contemporary matched controls.

MAIN OUTCOME MEASURE

Probability that a physician would prescribe a newly marketed medication over existing alternatives of three psychotropic classes: lisdexamfetamine among stimulants, paliperidone among antipsychotics, and desvenlafaxine among antidepressants. None of these medications represented radical breakthroughs in their respective classes.

RESULTS

For two of the three medications examined, attending a medical school with an active gift restriction policy was associated with reduced prescribing of the newly marketed drug. Physicians who attended a medical school with an active conflict of interest policy were less likely to prescribe lisdexamfetamine over older stimulants (adjusted odds ratio 0.44, 95% confidence interval 0.22 to 0.88; P=0.02) and paliperidone over older antipsychotics (0.25, 0.07 to 0.85; P=0.03). A significant effect was not observed for desvenlafaxine (1.54, 0.79 to 3.03; P=0.20). Among cohorts of students who had a longer exposure to the policy or were exposed to more stringent policies, prescribing rates were further reduced.

CONCLUSION

Exposure to a gift restriction policy during medical school was associated with reduced prescribing of two out of three newly introduced psychotropic medications.

Duloxetine versus other anti-depressive agents for depression

BACKGROUND

Although pharmacological and psychological interventions are both effective for major depression, in primary and secondary care settings antidepressant drugs remain the mainstay of treatment. Amongst antidepressants many different agents are available. Duloxetine hydrochloride is a dual reuptake inhibitor of serotonin and norepinephrine and has been licensed by the Food and Drug Administration in the US for major depressive disorder (MDD), generalised anxiety disorder, diabetic peripheral neuropathic pain, fibromyalgia and chronic musculoskeletal pain.

OBJECTIVES

To assess the evidence for the efficacy, acceptability and tolerability of duloxetine in comparison with all other antidepressant agents in the acute-phase treatment of major depression.

SEARCH METHODS

MEDLINE (1966 to 2012), EMBASE (1974 to 2012), the Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Register and the Cochrane Central Register of Controlled Trials up to March 2012. No language restriction was applied. Reference lists of relevant papers and previous systematic reviews were hand-searched. Pharmaceutical company marketing duloxetine and experts in this field were contacted for supplemental data.

SELECTION CRITERIA

Randomised controlled trials allocating patients with major depression to duloxetine versus any other antidepressive agent.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and a double-entry procedure was employed. Information extracted included study characteristics, participant characteristics, intervention details and outcome measures in terms of efficacy, acceptability and tolerability.

MAIN RESULTS

A total of 16 randomised controlled trials (overall 5735 participants) were included in this systematic review. Of these, three trials were unpublished. We found 11 studies (overall 3304 participants) comparing duloxetine with one selective serotonin reuptake inhibitor (SSRI) (six studies versus paroxetine, three studies versus escitalopram and two versus fluoxetine), four studies (overall 1978 participants) comparing duloxetine with a newer antidepressants (three with venlafaxine and one with desvenlafaxine, respectively) and one study (overall 453 participants) comparing duloxetine with an antipsychotic drug which is also used as an antidepressive agent, quetiapine. No studies were found comparing duloxetine with tricyclic antidepressants. The pooled confidence intervals were rather wide and there were no statistically significant differences in efficacy when comparing duloxetine with other antidepressants. However, when compared with escitalopram or venlafaxine, there was a higher rate of drop out due to any cause in the patients randomised to duloxetine (odds ratio (OR) 1.62; 95% confidence interval (CI) 1.01 to 2.62 and OR 1.56; 95% CI 1.14 to 2.15, respectively). There was also some weak evidence suggesting that patients taking duloxetine experienced more adverse events than paroxetine (OR 1.24; 95% CI 0.99 to 1.55).

AUTHORS' CONCLUSIONS

Duloxetine did not seem to provide a significant advantage in efficacy over other antidepressive agents for the acute-phase treatment of major depression. No differences in terms of efficacy were found, even though duloxetine was worse than some SSRIs (most of all, escitalopram) and newer antidepressants (like venlafaxine) in terms of acceptability and tolerability. Unfortunately, we only found evidence comparing duloxetine with a handful of other active antidepressive agents and only a few trials per comparison were found (in some cases we retrieved just one trial). This limited the power of the review to detect moderate, but clinically meaningful differences between the drugs. As many statistical tests have been used in the review, the findings from this review are better thought of as hypothesis forming rather than hypothesis testing and it would be very comforting to see the conclusions replicated in future trials. Most of included studies were sponsored by the drug industry manufacturing duloxetine. As for all other new investigational compounds, the potential for overestimation of treatment effect due to sponsorship bias should be borne in mind. In the present review no trials reported economic outcomes. Given that several SSRIs and the great majority of antidepressants are now available as generic formulation (only escitalopram, desvenlafaxine and duloxetine are still on patent), more comprehensive economic estimates of antidepressant treatment effect should be considered to better inform healthcare policy.

Field and laboratory studies of the fate and enantiomeric enrichment of venlafaxine and O-desmethylvenlafaxine under aerobic and anaerobic conditions

The stereoselectivity of R,S-venlafaxine and its metabolites R,S-O-desmethylvenlafaxine, N-desmethylvenlafaxine, O,N-didesmethylvenlafaxine, N,N-didesmethylvenlafaxine and tridesmethylvenlafaxine was studied in three processes: (i) anaerobic and aerobic laboratory scale tests; (ii) six wastewater treatment plants (WWTPs) operating under different conditions; and (iii) a variety of wastewater treatments including conventional activated sludge, natural attenuation along a receiving river stream and storage in operational and seasonal reservoirs. In the laboratory and field studies, the degradation of the venlafaxine yielded O-desmethylvenalfaxine as the dominant metabolite under aerobic and anaerobic conditions. Venlafaxine was almost exclusively converted to O-desmethylvenlafaxine under anaerobic conditions, but only a fraction of the drug was transformed to O-desmethylvenlafaxine under aerobic conditions. Degradation of venlafaxine involved only small stereoisomeric selectivity. In contrast, the degradation of O-desmethylvenlafaxine yielded remarkable S to R enrichment under aerobic conditions but none under anaerobic conditions. Determination of venlafaxine and its metabolites in the WWTPs agreed well with the stereoselectivity observed in the laboratory studies. Our results suggest that the levels of the drug and its metabolites and the stereoisomeric enrichment of the metabolite and its parent drug can be used for source tracking and for discrimination between domestic and nondomestic wastewater pollution. This was indeed demonstrated in the investigations carried out at the Jerusalem WWTP.

Effective and clinically meaningful non-hormonal hot flash therapies

Although many non-hormonal compounds have shown statistically significant benefit over placebo in hot flash randomized controlled trials (RCTs), these studies have varied considerably in basic methodology making it challenging to deduce which compounds have the greatest potential to provide clinically meaningful benefit. This review used evidence-based methodology closely mirroring the FDA and EMEA guidelines as a template to identify "well-designed" RCTs from which effective and clinically meaningful non-hormonal hot flash therapies could be identified. In addition, pertinent safety information was reviewed. Out of 3548 MEDLINE citations and abstracts, 51 well-designed hot flash RCTs were identified. From these trials, gabapentin, oxybutynin ER, desvenlafaxine, soy-derived isoflavones and black cohosh each showed a clinically meaningful treatment effect in at least 1 RCT. Among these 5 compounds, only gabapentin demonstrated consistent and statistically significant benefit over placebo in all of its well-designed RCTs. Desvenlafaxine, soy-derived isoflavones, and black cohosh demonstrated statistically significant benefit over placebo in 75%, 21%, and 17% of the well-designed RCTs for each compound, respectively. There was only 1 well-designed RCT using oxybutynin ER, which showed it to have a robust and clinically meaningful benefit. In terms of safety, there have been cardiovascular risks associated with desvenlafaxine use in postmenopausal women with hot flashes. The use of anticonvulsants, in general, has been associated with an absolute 0.21% increase in suicidal thoughts and behavior. Further research is needed with several of these nonhormonal compounds to replicate these findings and to also directly compare their efficacy and tolerability with those of hormone replacement therapy.

Occurrence and removal of lidocaine, tramadol, venlafaxine, and their metabolites in German wastewater treatment plants

PURPOSE

Some of the pharmaceuticals that are not extensively investigated in the aquatic environment are the anesthetic lidocaine (LDC), the analgesic tramadol (TRA), and the antidepressant venlafaxine (VEN). LDC metabolizes to 2,6-xylidine (2,6-DMA) and monoethylglycinexylidine (MEGX), TRA to O-desmethyltramadol (ODT), and VEN to O-desmethylvenlafaxine (ODV). Within this study, the distribution and behavior of these compounds in German wastewater treatment plants (WWTPs) were investigated.

METHODS

Samples of influents and effluents from WWTPs in Hesse, Germany were collected between January and September 2010. Analytes were extracted from wastewater samples by solid-phase extraction and from solid samples by sonication. Extracts were measured using gas chromatography/mass spectrometry.

RESULTS

LDC, TRA, VEN, ODT, and ODV were detected in all analyzed influent and effluent samples. 2,6-DMA could not be identified. MEGX was not detected. TRA and ODV were present in untreated wastewater at the highest concentrations (max, 1,129 (TRA) and 3,302 ng L⁻¹ (ODV)), while the concentrations of LDC and VEN were all significantly lower (mean, 135 (LDC) and 116 ng L⁻¹ (VEN)). All of the analytes were only partially removed in the WWTPs. The mean ratios between the concentrations of the metabolites and their respective parent compounds in influents were 4.7 (ODV/VEN) and 0.7 (ODT/TRA). These values remain approximately constant comparing influents and effluents.

CONCLUSIONS

LDC, TRA, VEN, ODT, and ODV are only partially removed from sewage water by WWTPs and thus are continuously discharged in respective recipient rivers. A further transformation of TRA and VEN into the known metabolites during treatment in the WWTPs is not observed.

Clinical outcomes following switch from venlafaxine ER to desvenlafaxine in nonresponders and responders

OBJECTIVE

This post hoc analysis examined efficacy and tolerability of open-label desvenlafaxine in patients with major depressive disorder switched from blinded placebo, venlafaxine extended release (ER), or desvenlafaxine.

RESEARCH DESIGN AND METHODS

Patients who completed 8 weeks of double-blind therapy with placebo (n = 176), venlafaxine ER (n = 175), or desvenlafaxine (n = 143) enrolled in a 10-month, open-label extension study and received desvenlafaxine 200 to 400 mg/d. Efficacy (17-item Hamilton Depression Rating Scale [HDRS(17)]) was assessed separately for nonresponders and responders to double-blind treatment. Tolerability during the first month of open-label desvenlafaxine was assessed.

RESULTS

Among nonresponders (n = 134) to double-blind placebo, venlafaxine ER, and desvenlafaxine, mean decreases in HDRS(17) scores were -10.9, -7.3, and -7.7, respectively; HDRS(17) response rates were 67%, 53%, and 48%, respectively. Although responders (n = 360) to double-blind placebo, venlafaxine ER, and desvenlafaxine had more modest decreases on the HDRS(17), response rates were higher (84%, 87%, and 83%, respectively). Rates of adverse events were highest during week 1, and decreased afterward for the remainder of the first month of treatment.

CONCLUSIONS

Among nonresponders to 8 weeks of double-blind venlafaxine ER, desvenlafaxine, or placebo, 48% to 67% subsequently responded to open-label desvenlafaxine. Over 80% of responders to double-blind therapy maintained response on open-label desvenlafaxine. The switch from venlafaxine ER to desvenlafaxine was well tolerated.

Influence of CYP2D6 genotype on the disposition of the enantiomers of venlafaxine and its major metabolites in postmortem femoral blood

Venlafaxine (VEN) is an antidepressant drug mainly metabolized by the cytochrome P450 (CYP) enzyme CYP2D6 to the active metabolite O-desmethylvenlafaxine (ODV). VEN is also metabolized to N-desmetylvenlafaxine (NDV) via CYP3A4. ODV and NDV are further metabolized to N,O-didesmethylvenlafaxine (DDV). VEN is a racemic mixture of the S- and R-enantiomers and these have in vitro displayed different degrees of serotonin and noradrenaline reuptake inhibition. The aim of the study was to investigate if an enantioselective analysis of VEN and its metabolites, in combination with genotyping for CYP2D6, could assist in the interpretation of forensic toxicological results in cases with different causes of deaths. Concentrations of the enantiomers of VEN and metabolites were determined in femoral blood obtained from 56 autopsy cases with different causes of death. The drug analysis was done by liquid chromatography tandem mass spectrometry (LC/MS/MS) and the CYP2D6 genotyping by PCR and pyrosequencing. The mean (median) enantiomeric S/R ratios of VEN, ODV, NDV and DDV were 0.99 (0.91), 2.17 (0.93), 0.92 (0.86) and 1.08 (1.03), respectively. However, a substantial variation in the relationship between the S- and R-enantiomers of VEN and metabolites was evident (S/R ratios ranging from 0.23 to 17.6). In six cases, a low S/R VEN ratio (mean 0.5) was associated with a high S/R ODV ratio (mean 11.9). Genotyping showed that these individuals carried two inactive CYP2D6 genes indicating a poor metabolizer phenotype. From these data we conclude that enantioselective analysis of VEN and ODV can predict if a person is a poor metabolizer genotype/phenotype for CYP2D6. Knowledge of the relationship between the S- and R-enantiomers of this antidepressant drug and its active metabolite is also important since the enantiomers display different pharmacodynamic profiles.

Clinical utility of desvenlafaxine 50 mg/d for treating MDD: a review of two randomized placebo-controlled trials for the practicing physician

BACKGROUND

Major depressive disorder (MDD) is a common, seriously impairing illness. Desvenlafaxine (administered as desvenlafaxine succinate) is the third serotonin-norepinephrine reuptake inhibitor (SNRI) approved in the United States for the treatment of MDD. Short-term clinical studies have demonstrated the efficacy and safety of 50 to 400 mg/d doses, with no evidence that doses greater than 50 mg/d confer additional benefit.

OBJECTIVE

This paper summarizes published data on the efficacy, safety, and tolerability of the desvenlafaxine 50-mg/d recommended therapeutic dose for MDD and discusses clinical practice considerations.

METHODS

A systematic review of MEDLINE, PsycINFO, and PubMed (all years through June 2009) was performed using the terms desvenlafaxine, DVS, and ODV. The criteria for inclusion in the review were a double-blind design, a placebo control or active comparator group, the 50-mg desvenlafaxine dose group, and enrollment of patients with a diagnosis of MDD. Posters were included if they reported on a study that was subsequently published in a manuscript.

RESULTS

Overall results of two randomized, placebo-controlled, 8-week clinical trials demonstrated the efficacy of desvenlafaxine 50 mg/d for MDD. Statistically significant improvements compared with placebo were observed on the primary efficacy measure (17-item Hamilton Rating Scale for Depression [HAM-D(17)] total score; P < 0.05). Significant differences were observed on several secondary measures (Montgomery Asberg Depression Rating Scale scores in both trials [P < 0.05]; Clinical Global Impressions-Improvement scores [P < or = 0.01], Clinical Global Impressions-Severity scores [P < or = 0.01], HAM-D(17) response [P < or = 0.01] and remission [P < 0.05] in one trial each). Functional outcomes measures (Sheehan Disability Scale total and World Health Organization 5-Item Well-Being Index scores) were significant in both trials (P < 0.05). Safety results indicate desvenlafaxine treatment was safe and well tolerated; findings were consistent with the SNRI class. The generalizability of these findings is limited by the study protocols, which excluded patients with unstable comorbid medical conditions and also those with other Axis 1 and 2 psychiatric illnesses. Additionally, comparisons with other SNRIs are challenging given differences in study design. Desvenlafaxine can be initiated with the 50-mg/d therapeutic dose without titration and provides efficacy with rates of discontinuation due to treatment-emergent adverse events similar to placebo. In vitro data indicate desvenlafaxine has minimal inhibitory effects on cytochrome P450 (CYP) 2D6 and clinical studies show desvenlafaxine does not have a clinically relevant effect on CYP2D6 metabolism. In vitro data also indicate desvenlafaxine is not a substrate or inhibitor of the p-glycoprotein transporter. Plasma protein binding of desvenlafaxine is low (30%) and independent of drug concentration. Bioavailability is high at 80% after oral administration and is not affected by food.

CONCLUSIONS

Desvenlafaxine 50 mg/d has demonstrated efficacy, safety, and tolerability for the treatment of MDD in two placebo-controlled trials. The metabolic profile of desvenlafaxine suggests a low risk of drug-drug interactions owing to minimal inhibitory effects on CYP2D6, lack of interaction with p-glycoprotein, and low protein binding.

Desvenlafaxine: application withdrawal. Desvenlafaxine: withdrawal of marketing application for depression also

A welcome move! This psychoactive agent has an unfavourable risk-benefit balance in both hot flushes and depression.

[Non-hormonal treatment for vasomotor symptoms during menopause: role of desvenlafaxine]

OBJECTIVE

To review the published data that include Selective Serotonin Reuptake Inhibitors (SSRIs) and Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs), especially desvenlafaxine, on vasomotor symptoms (VMS).

METHODS

This review is based on published data in Medline (1990-2009) for studies on SSRI and SNRIs, especially desvenlafaxine, and VMS.

RESULTS

There is increasing evidence that both norepinephrine and serotonin are associated with the communication and modulation of the temperature homeostasis maintained by the hypothalamus. Different studies demonstrated the modest efficacy of SSRIs and SNRIs on VMS. Recently, a program of clinical trials with desvenlafaxine (a salt from the major metabolite of venlafaxine) has been developed for VMS. Currently, there are three randomized, double-blind clinical trials published, showing a significantly higher efficacy of desvenlafaxine versus placebo on VMS. There were also increased minor side effects with desvenlafaxine, especially nausea, at the beginning of the treatment.

CONCLUSIONS

A non-hormonal alternative--desvenlafaxine--has proven efficacy for VMS. There was also an increase in minor side effects, especially nausea, at the beginning of the treatment. There are clear subgroups of patients with VMS eligible, such as women with hormone-dependent cancers, women who do not want to be treated with hormone therapy or just want to get relief of their vasomotor symptoms.

New drug update: 2008

Only 16 new therapeutic agents were marketed in the United States in 2008, the lowest number in many years. Four new drugs have been selected for consideration in this review. The uses and most important properties of each agent are considered, and a rating for each new drug is provided using the New Drug Comparison Rating (NDCR) system developed by the author.

Desvenlafaxine for the treatment of vasomotor symptoms associated with menopause: a double-blind, randomized, placebo-controlled trial of efficacy and safety

OBJECTIVE

The objective of the study was to assess the efficacy and safety of desvenlafaxine (administered as desvenlafaxine succinate) for the treatment of vasomotor symptoms.

STUDY DESIGN

This was a 26 week, double-blind, placebo-controlled trial of 567 postmenopausal women (mean age, 53.7 years; time since natural menopause, 4.8 years) experiencing 50 or more hot flushes (HFs) per week, randomly assigned to desvenlafaxine (100 or 150 mg) or placebo. Change from baseline in average daily number of moderate to severe HFs and average daily HF severity were compared with placebo at weeks 4, 12, and 26.

RESULTS

A significantly greater decrease from baseline in number of HFs occurred at weeks 4 and 12 with 100 and 150 mg desvenlafaxine compared with placebo (week 12 reductions: 60%, 66%, and 47%, respectively; all P < or = .002). Only the 150 mg dose showed significant improvement from baseline at 26 weeks compared with placebo (week 26 reductions: 61%, 69%, and 51%, respectively), although the study was not powered to demonstrate efficacy beyond the initial 12 weeks of therapy. The average daily severity decreased significantly more at weeks 4 and 12 with desvenlafaxine compared with placebo (all P < or = .002). Significantly more desvenlafaxine-treated subjects than placebo-treated subjects discontinued because of adverse events during week 1 only.

CONCLUSION

Desvenlafaxine is an effective treatment for menopausal HFs.

Desvenlafaxine, a serotonin-norepinephrine uptake inhibitor for major depressive disorder, neuropathic pain and the vasomotor symptoms associated with menopause

Desvenlafaxine, a serotonin-norepinephrine reuptake inhibitor (SNRI) developed by Wyeth, is a novel salt form of the isolated major active metabolite of the antidepressant venlafaxine. Desvenlafaxine was developed as a slow-release tablet formulation and rapidly penetrates the brain upon administration supporting its direct effects on neuronal systems of the brain. Unlike various other antidepressants including venlafaxine, desvenlafaxine is not metabolized by cytochrome p450 (CYP) enzyme pathways and is associated with minimal inhibition of CYP enzymes. This feature results in a comparatively low risk of drug-drug interaction and consistent intra-individual and inter-individual pharmacokinetic profiles. Desvenlafaxine has been recently approved by the US FDA for the treatment of major depressive disorder (MDD) based on a series of randomized, double-blind, placebo-controlled clinical trials indicating efficacy and safety for patients with MDD. Studies have also supported the potential utility of desvenlafaxine in the treatment of vasomotor symptoms of menopause, anxiety symptoms and painful physical symptoms. However, concerns including mixed efficacy and adverse events need to be further explored in future studies.

Desvenlafaxine and venlafaxine exert minimal in vitro inhibition of human cytochrome P450 and P-glycoprotein activities

OBJECTIVE

Identification of potential pharmacokinetic drug-drug interactions is an important step in clinical drug development.We assessed and compared the drug-drug interaction potential of desvenlafaxine and venlafaxine, based on their inhibitory potency on human cytochrome P450 (CYP) and P-glycoprotein (P-gp) activities in vitro.

METHODS

Reversible inhibition of CYP1A2, CYP2A6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4, and mechanism-based inhibition of CYP2C9, CYP2C19, CYP2D6, and CYP3A activity by desvenlafaxine and venlafaxine were determined in human liver microsomes.Whether these drugs were substrates for efflux or inhibitors of P-gp were determined in Caco-2 monolayers.

RESULTS

Desvenlafaxine and venlafaxine showed little or no reversible inhibition of various CYP enzymes (concentration that inhibits 50% [IC50] or inhibition constant [Ki] ~ or >100 muM). In addition, neither drug acted as a mechanism-based inhibitor of CYP2C9, CYP2C19, CYP2D6, or CYP3A as they did not reduce the IC50 value for any of these enzymes in the presence of preincubations with or without a nicotinamide adenine dinucleotide phosphate-regenerating system. Desvenlafaxine and venlafaxine showed little inhibition of P-gp activity (IC50 values >250 muM) and did not act as substrates (efflux ratios <2) for efflux in Caco-2 monolayers.

CONCLUSIONS

Considering in vitro and available clinical data, desvenlafaxine and venlafaxine appear to have low potential for pharmacokinetic drug-drug interactions via inhibiting the metabolic clearance of concomitant drugs that are substrates of various CYP enzymes, in particular CYP2D6. In addition, these data suggest that desvenlafaxine and venlafaxine exhibit little potential for pharmacokinetic interactions with concomitant drugs that are substrates or inhibitors of P-gp.

Analysis of depressive symptoms in patients with major depressive disorder treated with desvenlafaxine or placebo

BACKGROUND

The aim of this study was to evaluate the impact of desvenlafaxine on a broad range of major depressive disorder (MDD) symptoms.

METHODS

Data were pooled from 9 double-blind, randomized, placebo-controlled, 8-week studies of desvenlafaxine in adult outpatients with MDD. Intent-to-treat participants received fixed- (50, 100, 200, or 400 mg/d; n = 1342) or flexible-dose (100 to 400 mg/d, n = 463) desvenlafaxine or placebo (n = 1108). Final on-therapy scores for individual items of the 17-item Hamilton Rating Scale for Depression (HAMD17) and the Montgomery Asberg Depression Rating Scale (MADRS) were compared between groups using analysis of covariance. Efficacy at different doses was examined using the subset of fixed-dose studies.

RESULTS

Based on differences in adjusted mean changes from baseline (desvenlafaxine vs placebo), statistically significant advantages with desvenlafaxine (50 to 400 mg/d, all doses pooled) vs placebo were seen for 10 of the 17 HAM-D17 items: depressed mood (-0.4; P < 0.001), feelings of guilt (-0.2; P < 0.001), suicide (-0.1; P < 0.001), late insomnia (-0.1; P = 0.001), work and activities (-0.2; P < 0.001), psychomotor retardation (-0.1; P < 0.001), agitation (-0.1; P < 0.001), psychic anxiety (-0.3; P < 0.001), general somatic symptoms (-0.2; P < 0.001), and genital symptoms (-0.1; P = 0.003). Desvenlafaxine (50 to 400 mg/d, pooled) was significantly better than placebo on all MADRS items (range: -0.1 to -0.5; all P </= 0.019), except "reduced appetite" (-0.01, P > 0.05). Symptom relief was similar with all desvenlafaxine doses examined, including 50 mg/d.

CONCLUSIONS

Shortterm desvenlafaxine therapy (50 to 400 mg/d) improved a broad range of emotional and physical symptoms in outpatients with MDD.

Efficacy, safety, and tolerability of desvenlafaxine 50 mg/day and 100 mg/day in outpatients with major depressive disorder

OBJECTIVE

To assess the efficacy, safety, and tolerability of 50- and 100-mg/day doses of desvenlafaxine (administered as desvenlafaxine succinate), a serotonin-norepinephrine reuptake inhibitor, for the treatment of major depressive disorder (MDD).

RESEARCH DESIGN AND METHODS

Patients with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) MDD and 17-item Hamilton Rating Scale for Depression (HAM-D(17)) scores > or =20 were randomly assigned to double-blind placebo or desvenlafaxine treatment (fixed dose of 50 mg/day or 100 mg/day) for 8 weeks. The primary efficacy measure was the HAM-D(17). Changes from baseline in HAM-D(17) scores were analyzed using analysis of covariance. The final on-therapy evaluation was the primary endpoint for efficacy analyses, using last-observation-carried-forward data. MAIN OUTCOMES MEASURES AND RESULTS: The intent-to-treat population included 447 patients. Desvenlafaxine 50 mg was associated with a significantly greater adjusted mean change from baseline on the HAM-D(17) (-11.5) compared with placebo (-9.5, p=0.018); the 100-mg dose group (-11.0) did not achieve statistical significance (p=0.065). The 100-mg dose group experienced significant improvements compared with placebo on several secondary efficacy measures, including the 6-item Hamilton Depression Rating Scale (p=0.038) and the Visual Analog Scale-Pain Intensity total score (p=0.041). Both desvenlafaxine doses were generally well-tolerated. The most common adverse events (incidence > or =10% in either desvenlafaxine group and twice the rate of placebo) were dry mouth, constipation, insomnia, decreased appetite, hyperhidrosis, and dizziness.

CONCLUSIONS

These results demonstrate efficacy, safety, and tolerability of desvenlafaxine 50 mg/day for treating MDD. The significant findings on secondary measures support the efficacy of desvenlafaxine 100 mg, as seen in other trials. Conclusions may be limited by the exclusion of MDD patients with comorbid conditions and the short-term desvenlafaxine treatment duration.

Serum concentrations of venlafaxine and its metabolites O-desmethylvenlafaxine and N-desmethylvenlafaxine in heterozygous carriers of the CYP2D6*3, *4 or *5 allele

OBJECTIVE

Increased systemic exposure of the antidepressant venlafaxine and increased risk of side effects has previously been observed in patients with defective CYP2D6 function [poor metabolisers (PMs)]. The aim of this study was to evaluate venlafaxine pharmacokinetics in carriers of one functional and one defective CYP2D6 allele [heterozygous extensive metabolisers (HEMs)].

METHODS

Data was collected retrospectively from a therapeutic drug-monitoring database. All CYP-genotyped patients with steady-state serum concentration measurements of venlafaxine and metabolites were included in the study. Patients were divided in groups: *1/*1 [homozygous extensive metabolisers (EMs)], *1/*3, *4 or *5 (HEMs) and *4/*4 (PMs). Dose-adjusted serum concentrations of venlafaxine, O-desmethylvenlafaxine, N-desmethylvenlafaxine, and the metabolic ratio (O-desmethylvenlafaxine/venlafaxine) were compared between the different genotype groups.

RESULTS

The sum of venlafaxine and O-desmethylvenlafaxine serum concentrations was not significantly different between genotype groups. Metabolic ratio was 50% lower in HEMs (n = 18) than in EMs (n = 20) (p < 0.05). Serum concentration of N-desmethylvenlafaxine was 5.5-fold higher in HEMs (p < 0.01) and 22-fold higher in PMs (p < 0.001) than in EMs.

CONCLUSION

The study showed a shift in the metabolic pathway resulting in substantially higher levels of N-desmethylvenlafaxine in HEMs than in EMs. The metabolic pattern of venlafaxine in HEMs was similar to previous observations in PMs and possibly represents an increased risk of venlafaxine-related side effects in HEM patients.

Analysis of the second generation antidepressant venlafaxine and its main active metabolite O-desmethylvenlafaxine in human plasma by HPLC with spectrofluorimetric detection

A high-performance liquid chromatographic method has been developed for the determination of the recent serotonin and norepinephrine reuptake inhibitor (SNRI) venlafaxine and its main active metabolite, O-desmethylvenlafaxine, in human plasma. Separation was obtained by using a reversed-phase column (C8, 150 x 4.6 mm I.D., 5 microm) and a mobile phase composed of 75% aqueous phosphate buffer containing triethylamine at pH 6.8 and 25% acetonitrile. Fluorescence detection was used, exciting at lambda=238 nm and monitoring the emission at lambda=300 nm. Citalopram was used as the internal standard. A careful pre-treatment of plasma samples was developed, using solid-phase extraction with C1 cartridges (100 mg, 1 mL). The limit of quantification (LOQ) was 1.0 ng mL(-1) and the limit of detection (LOD) was 0.3 ng mL(-1) for both analytes. The method was applied with success to plasma samples taken from patients undergoing treatment with venlafaxine. Precision data, as well as accuracy results, were satisfactory and no interference from other drugs was found. Hence, the method is suitable for therapeutic drug monitoring of venlafaxine and its main metabolite in depressed patients' plasma.

Effect of terbinafine and voriconazole on the pharmacokinetics of the antidepressant venlafaxine

This study investigated the effect of terbinafine and voriconazole on the pharmacokinetics of venlafaxine in healthy volunteers. Plasma concentrations of venlafaxine and O-desmethylvenlafaxine (ODV) were measured after ingestion of 75 mg venlafaxine without pretreatment (control), after terbinafine pretreatment, or after voriconazole pretreatment. During the terbinafine phase, the area under the plasma concentration-time curve (AUC(0-infinity)) of venlafaxine was on average 490% (P<0.001) and that of ODV 57% (P<0.001) of the corresponding control value. Terbinafine decreased the AUC(0-infinity) ratio of ODV over venlafaxine by 82% (P<0.001). Voriconazole slightly increased the sum of AUC(0-infinity) of venlafaxine plus AUC(0-infinity) of ODV (active moiety) by 31% (P<0.001). The most likely mechanism for the interaction between terbinafine and venlafaxine is the inhibition of CYP2D6-mediated O-demethylation of venlafaxine, whereas the minor effects of voriconazole are probably due to the inhibition of CYP3A4-, CYP2C9-, or CYP2C19-mediated metabolism of venlafaxine.

Desvenlafaxine Succinate Identifies Novel Antagonist Binding Determinants in the Human Norepinephrine Transporter

Desvenlafaxine succinate (DVS) is a recently introduced antagonist of the human norepinephrine and serotonin transporters (hNET and hSERT, respectively), currently in clinical development for use in the treatment of major depressive disorder and vasomotor symptoms associated with menopause. Initial evaluation of the pharmacological properties of DVS (J Pharmacol Exp Ther 318:657-665, 2006) revealed significantly reduced potency for the hNET expressed in membranes compared with whole cells when competing for [(3)H]nisoxetine (NIS) binding. Using hNET in transfected human embryonic kidney-293 cells, this difference in potency for DVS at sites labeled by [(3)H]NIS was found to distinguish DVS, the DVS analog rac-(1-[1-(3-chloro-phenyl)-2-(4-methylpiperazin-1-yl)-ethyl]cyclohexanol (WY-46824), methylphenidate, and the cocaine analog 3beta-(4-iodophenyl)tropane-2beta-carboxylic acid methyl ester (RTI-55) from other hNET antagonists, such as NIS, mazindol, tricyclic antidepressants, and cocaine. These differences seem not to arise from preparation-specific perturbations of ligand intrinsic affinity or antagonist-specific surface trafficking but rather from protein conformational alterations that perturb the relationships between distinct hNET binding sites. In an initial search for molecular features that differentially define antagonist binding determinants, we document that Val148 in hNET transmembrane domain 3 selectively disrupts NIS binding but not that of DVS.

Venlafaxine in the treatment of children and adolescents with attention-deficit/hyperactivity disorder

OBJECTIVE

The objectives of this pilot study were to explore the changes in symptom severity, tolerability, and the pharmacodynamics of venlafaxine treatment in youths with attention-deficit/hyperactivity disorder (ADHD).

METHODS

This was a 2-week, open-label, outpatient trial of venlafaxine in children and adolescents, ages 5-17 years, with ADHD. Three dosing strata, 0.5, 1.0, and 2.0 mg/kg per day, were examined. ADHD symptom severity and improvement assessments included the ADHD Rating Scale (ARS-IV) and the Clinical Global Impressions Scale (CGI). During this study, venlafaxine, O-desmethylvenlafaxine (ODV), norepinephrine, and serotonin concentrations were obtained.

RESULTS

Thirty-eight participants (33 males) were treated in this trial. Overall, parent-completed and teacher-completed ARS-IV total scores showed a statistically significant positive change at the end of the study when compared to baseline (p < 0.05). Significant increases in plasma venlafaxine concentrations were observed at day 15 when compared to day 8 (p = 0.04). In addition, plasma norepinephrine and serotonin concentrations were found to be significantly decreased from baseline at end of study (p < 0.05). Four patients ended participation in the study prematurely: lost to follow up (n = 2), withdrawal of consent (n = 1), and worsening of ADHD symptoms after 8 days of treatment (n = 1). There were no discontinuations due to other adverse events.

CONCLUSIONS

Venlafaxine appeared to offer some benefit and appears to be relatively safe for the short-term treatment of ADHD in this open-label trial. The pharmacodynamics of venlafaxine in youths are consistent with serotonergic and neuradrenergic modulation.

Simultaneous stereoselective analysis of venlafaxine and O-desmethylvenlafaxine enantiomers in human plasma by HPLC-ESI/MS using a vancomycin chiral column

A high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI/MS) method for simultaneous stereoselective analysis of venlafaxine (VEN) and its major metabolite O-desmethylvenlafaxine (ODV) enantiomers in human plasma has been developed and validated. Chiral chromatography is performed on the CHRIOBIOTIC V (5 microm, 250 mm x 4.6 mm) column with mobile phase constituted of 30 mmol/l ammonium acetate-methanol (15:85, pH 6.0) at a flow rate of 1.0 ml/min and a postcolumn splitting ratio of 3:1. The compounds were ionized in the electrospray ionization (ESI) ion source of the mass spectrometer and detected using the selected ion recording (SIR) mode. Calibration curves obtained from spiked plasma were linear in the range of 5.0-400 ng/ml for S-(+)-VEN and R-(-)-VEN, 4.0-280 ng/ml for S-(+)-ODV and R-(-)-ODV, respectively, with linear correlation coefficient all above 0.999. The average extraction recoveries for all the four analytes were above 76%. The methodology recoveries were higher than 92%. The limit of detection were 1.0 ng/ml for S-(+)-VEN and R-(-)-VEN, 1.5 ng/ml for S-(+)-ODV and R-(-)-ODV, respectively. The intra- and inter-day variation coefficients were less than 9%.

A double-blind, placebo-controlled study of the efficacy and safety of desvenlafaxine succinate in the treatment of major depressive disorder

OBJECTIVE

This study evaluated the efficacy and safety of desvenlafaxine succinate extended-release in major depressive disorder (MDD).

METHOD

Adult outpatients with DSM-IV-defined MDD were randomly assigned to desvenlafaxine 100 mg/day (N = 114), 200 mg/day (N = 116), or 400 mg/day (N = 113) or placebo (N = 118) for 8 weeks. Efficacy variables included change from baseline in the 17-item Hamilton Rating Scale for Depression (HAM-D(17), the primary efficacy measure), Clinical Global Impressions-Improvement scale (CGI-I), Montgomery-Asberg Depression Rating Scale, Clinical Global Impressions-Severity of Illness scale (CGI-S), rates of response (> or = 50% decrease from baseline HAM-D(17) score) and remission (HAM-D(17) score < or =7), and Visual Analog Scale-Pain Intensity overall score. The study was conducted from November 2003 to November 2004.

RESULTS

At the final on-therapy evaluation, the mean HAM-D(17) scores for desvenlafaxine 100 mg/day (12.75) and 400 mg/day (12.50) were significantly lower than for placebo (15.31; p = .0038 and p = .0023, respectively); for desvenlafaxine 200 mg/day, the mean score was 13.31 (p = .0764). CGI-I and Montgomery-Asberg Depression Rating Scale results were significant for all groups; CGI-S results were significant with 100 mg/day and 400 mg/day. Response rates were significantly greater for desven-lafaxine 100 mg/day (51%) and 400 mg/day (48%) versus placebo (35%; p = .017 and p = .046, respectively); the response rate for desvenlafaxine 200 mg/day was 45% (p = .142). Remission rates were significantly greater for desvenlafaxine 400 mg/day (32%) versus placebo (19%; p = .035); remission rates were 30% for desvenlafaxine 100 mg/day (p = .093) and 28% for desvenlafaxine 200 mg/day (p = .126). Visual Analog Scale-Pain Intensity results were significant for desvenlafaxine 100 mg/day versus placebo (p = .002), but not for the higher doses. The most commonly reported adverse events were nausea, insomnia, somnolence, dry mouth, dizziness, sweating, nervousness, anorexia, constipation, asthenia, and abnormal ejaculation/orgasm.

CONCLUSIONS

Desvenlafaxine is effective and well tolerated in the short-term treatment of MDD.

Alleviation of thermoregulatory dysfunction with the new serotonin and norepinephrine reuptake inhibitor desvenlafaxine succinate in ovariectomized rodent models

Hot flushes and night sweats, referred to as vasomotor symptoms (VMS), are presumed to be a result of declining hormone levels and are the principal menopausal symptoms for which women seek medical treatment. To date, estrogens and/or some progestins are the most effective therapeutics for alleviating VMS; however, these therapies may not be appropriate for all women. Therefore, nonhormonal therapies are being evaluated. The present study investigated a new reuptake inhibitor, desvenlafaxine succinate (DVS), in animal models of temperature dysfunction. Both models used are based on measuring changes in tail-skin temperature (TST) in ovariectomized (OVX) rats. The first relies on naloxone-induced withdrawal in morphine-dependent (MD) OVX rats, resulting in an acute rise in TST. The second depends on an OVX-induced loss of TST decreases during the dark phase as measured by telemetry. An initial evaluation demonstrated abatement of the rise in TST with long-term administration of ethinyl estradiol or with a single oral dose of DVS (130 mg/kg) in the MD model. Further evaluation showed that orally administered DVS acutely and dose dependently (10-100 mg/kg) abated a naloxone-induced rise in TST of MD rats and alleviated OVX-induced temperature dysfunction in the telemetry model. Oral administration of DVS to OVX rats caused significant increases in serotonin and norepinephrine levels in the preoptic area of the hypothalamus, a key region of the brain involved in temperature regulation. These preclinical studies provide evidence that DVS directly impacts thermoregulatory dysfunction in OVX rats and may have utility in alleviating VMS associated with menopause.

Employing atmospheric pressure photoionization in liquid chromatography/tandem mass spectrometry to minimize ion suppression and matrix effects for the quantification of venlafaxine and O-desmethylvenlafaxine

During the development of a method for quantitative determination of venlafaxine and its major metabolite O-desmethylvenlafaxine, elevated concentrations of the analyte as well as co-eluting matrix compounds caused ion suppression. This ion suppression was inconsistent and therefore influenced the reproducibility of detection. The use of atmospheric pressure photoionization (APPI) in the positive mode was investigated as a tool to circumvent this problem. Employing APPI resulted in negligible ion suppression and increased linearity of the concentration range. A selective, sensitive and rapid liquid chromatography/tandem mass spectrometry method for the determination of venlafaxine and its major metabolite O-desmethylvenlafaxine in human plasma was developed. The analyte was extracted from plasma into tert-butyl methyl ether followed by back extraction into 2% formic acid. An Agilent 1100 high-performance liquid chromatography (HPLC) system, employing reversed-phase chromatography on a cyano column, coupled to an Applied Biosystems API 3000 triple quadrupole mass spectrometer set to multiple reaction monitoring (MRM) mode, was used for separation and detection of the analytes. The method was validated between 2.36-605 ng per mL with a mean recovery of approximately 88% for both parent compound and metabolite analytes. APPI technology was employed to improve the reproducibility of detection enabling rapid, selective and sensitive quantification of venlafaxine and O-desmethylvenlafaxine in human plasma samples.

New products and regimens (since 2003)

The downturn in the use of hormone replacement therapy since the original publication of the Women's Health Initiative (2002) and Million Women studies (2003) has now stabilized. New products are now being developed which maintain benefits and minimise risks. However, some useful products have been withdrawn by Pharma companies through profitability decisions; other products will regrettably not be launched despite favorable data. New low- and ultra-low-dose oral preparations (containing 0.3 mg conjugated equine estrogens and 0.5 mg estradiol, respectively) appear to maintain benefits for symptom relief and osteoporosis whilst minimizing side-effects and risks. A 14 microg transdermal system appears to maintain bone protection without the need for endometrial protection. New progestogens can minimize progestogenic side-effects through antiandrogenic and antimineralocorticoid effects, e.g. drospirenone, bioidentical progesterone and selective progesterone receptor modulators. A new female androgen patch has been licensed in Europe for treatment of low libido causing distress (hypoactive sexual desire disorder) in surgically menopaused women on estrogen therapy. A non-hormonal option, desvenlafaxine succinate (a serotonin and noradrenaline reuptake inhibitor), for vasomotor symptoms is currently in phase-III clinical trial stage and should be launched in the next year. Additionally, a selective estrogen receptor modulator/conjugated equine estrogen preparation combination currently in phase-III clinical trials is showing encouraging data for efficacy/risks and should provide a further option for women using hormone therapy in the future.