Severe acute cardiomyopathy associated with venlafaxine overdose and possible role of CYP2D6 and CYP2C19 polymorphisms

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.

Case Report: Co-occurrence of Myocarditis and Thrombotic Microangiopathy Limited to the Heart in a COVID-19 Patient

We report on an impressive case of a previously healthy 47-year-old female Caucasian SARS-CoV-2 positive patient who died within 48 h after initial cardiac symptoms. Autopsy revealed necrotizing myocarditis and extensive microthrombosis as the cause of death. The interesting feature of this case is the combination of both myocarditis and extensive localized microthrombosis of cardiac capillaries. Microthrombosis was not present in other organs, and the patient did not show typical features of diffuse alveolar damage in the lungs. Taken together, our morphologic findings illustrate the angiocentric, microangiopathic, thromboinflammatory disease with significant thrombotic diathesis prevalent in COVID-19, which has been previously described in the literature, likely warranting thromboprophylaxis even in oligosymptomatic circumstances. This case also delineates several potential etiologies for microthrombosis, i.e., inflammatory reactions and primary hypercoagulative states. Further systematic analyses on risk stratification for receipt of prophylactic anticoagulation in COVID-19 are urgently required.

The Influence of Combined CYP2D6 and CYP2C19 Genotypes on Venlafaxine and O-Desmethylvenlafaxine Concentrations in a Large Patient Cohort

PURPOSE

The antidepressant venlafaxine is largely O-desmethylated by CYP2D6, whereas CYP2C19 mediates an alternative metabolic route of venlafaxine through N-desmethylation. The aim of this study was to investigate the combined effect of genotype-predicted CYP2D6 and CYP2C19 phenotypes on serum concentrations of venlafaxine and metabolites in a large patient population.

METHODS

Patients were retrospectively included from a therapeutic drug monitoring service at Diakonhjemmet Hospital in Oslo (Norway) between January 01, 2007, and December 31, 2017. The study population was divided into different phenotype subgroups according to the combinations of CYP2D6/CYP2C19 phenotypes; intermediate metabolizers (IMs), poor metabolizers (PMs) and ultrarapid metabolizers, and compared using combined normal metabolizers (NMs) as reference.

FINDINGS

The dose-adjusted serum concentration of venlafaxine was 4- and 13-fold increased in combined CYP2D6 IM/CYP2C19 PMs and combined PMs, respectively, compared with combined NMs (P < 0.001). The sum concentration of venlafaxine + ODV (pharmacological active moiety) was increased 1.9 and 3.6-fold, respectively, in the same phenotype groups. Furthermore, the dose-adjusted active moiety exposure was similar in combined IMs as combined CYP2D6 PM/CYP2C19 NMs. CYP2D6 and CYP2C19 phenotypes explained 46% of the interindividual variability in dose-adjusted venlafaxine serum concentrations, whereas CYP2D6 alone explained 24%.

CONCLUSIONS

The combined CYP2D6/CYP2C19 phenotype has a significant impact on serum concentrations of venlafaxine and also on the active moiety of venlafaxine + ODV, than CYP2D6 alone. In clinical practice, it is therefore important to take into account phenotype variabilities of both enzymes when assessing the risk of dose-dependent adverse effects during venlafaxine treatment.

Potential Pharmacokinetic Drug-Drug Interactions between Cannabinoids and Drugs Used for Chronic Pain

Choosing an appropriate treatment for chronic pain remains problematic, and despite the available medication for its treatment, still, many patients complain about pain and appeal to the use of cannabis derivatives for pain control. However, few data have been provided to clinicians about the pharmacokinetic drug-drug interactions of cannabinoids with other concomitant administered medications. Therefore, the aim of this brief review is to assess the interactions between cannabinoids and pain medication through drug transporters (ATP-binding cassette superfamily members) and/or metabolizing enzymes (cytochromes P450 and glucuronyl transferases).

The Effect of Venlafaxine on Electrocardiogram Intervals During Treatment for Depression in Older Adults

PURPOSE/BACKGROUND

Venlafaxine is a commonly used antidepressant with both serotonergic and noradrenergic activity. There are concerns that it may prolong the corrected QT interval (QTc), and older adults may be at higher risk for this adverse effect, especially at higher dosages of the medication.

METHODS/PROCEDURES

In this secondary analysis of a prospective clinical trial, we measured changes in QTc and other electrocardiogram (ECG) parameters in 169 adults 60 years or older with a major depressive disorder treated acutely with venlafaxine extended release up to 300 mg daily. We examined the relationship of venlafaxine dosage and ECG parameters, as well as the relationship between serum levels of venlafaxine and ECG parameters.

FINDINGS/RESULTS

Venlafaxine exposure was not associated with an increase in QTc. Heart rate increased with venlafaxine treatment, whereas the PR interval shortened, and QRS width did not change significantly. The QTc change from baseline was not associated with venlafaxine dosages or serum concentrations. Age, sex, cardiovascular comorbidities, and depression remission status did not predict changes in QTc with venlafaxine.

IMPLICATIONS/CONCLUSIONS

Venlafaxine treatment did not prolong QTc or other ECG parameters, even in high dosages in older depressed adults. These findings indicate that venlafaxine does not significantly affect cardiac conduction in most older patients.

Toxicological Assessment of Venlafaxine: Acute and Subchronic Toxicity Study in Rats

Antidepressants are the most commonly prescribed drugs for psychiatric treatment, and venlafaxine (VEN) is one of the most popular options. Venlafaxine is a nontricyclic dual-acting serotonin-norepinephrine reuptake inhibitor. Although an increased incidence of acute toxicity and addiction has been reported, controlled studies examining its toxic effects on different organs are still lacking. This study investigated the possible toxic effects of VEN on the liver, kidney, and gastric tissues. Three groups of rats were administered saline, a single LD₅₀ dose (350 mg/kg), or 100 mg/kg VEN daily, followed by increases in the dose of 50 mg/kg every 10 days for 30 days (about 10 times the therapeutic doses). The following parameters of liver and kidney injury were then assayed: alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transferase, prothrombin time, partial thromboplastin time, blood urea nitrogen, and serum creatinine. A histopathological examination was then conducted. Both acute and subchronic administration of VEN produced multiple clinical manifestations in the experimental animals, including seizures, coma, and even death. Moreover, the liver and renal function tests indicated injury in these tissues. Furthermore, the histopathological examination showed signs of organ toxicity after both acute and chronic VEN exposure. This study has shown that VEN has harmful effects on the liver, kidney, and stomach in either a single high dose (LD₅₀) or repeated exposure to 10 times the therapeutic doses. As a result, strategies to increase awareness of these effects among physicians and the public are needed because this drug may be addictive.

Should a routine genotyping of CYP2D6 and CYP2C19 genetic polymorphisms be recommended to predict venlafaxine efficacy in depressed patients treated in psychiatric settings?

AIM

The antidepressant venlafaxine (VEN) is metabolized by CYP2D6 and CYP2C19. The aim of this study was to assess the relevance of generalizing to daily practice the genotyping of CYP2D6 and CYP2C19 to predict VEN efficacy in depressed patients treated in psychiatric settings.

PATIENTS & METHODS

This study was nested in a naturalistic cohort, with 206 patients requiring a new antidepressant treatment and genotyped for CYP2D6 *3, *4, *5 del, *6, *2xN, *10, *41 and CYP2C19 *2, *3, *4, *5, *17 alleles.

RESULTS

CYP2D6 and CYP2C19 phenotypes were associated neither with the Hamilton depression rating scale score improvement, nor with response and remission.

CONCLUSION

Routine CYP2D6 and CYP2C19 genotyping cannot be recommended to predict VEN efficacy in depressed patients treated in psychiatry settings.

Palpitations and Asthenia Associated with Venlafaxine in a CYP2D6 Poor Metabolizer and CYP2C19 Intermediate Metabolizer

Cardiotoxicity has been extensively reported in venlafaxine (VEN) overdoses. Asthenia is also among the common side effects described for this antidepressant. VEN is metabolized mainly by CYP2D6 and to a minor extent by CYP2C19 to the major active metabolite O-desmethylvenlafaxine (ODV). Altered pharmacokinetic parameters in patients with polymorphisms in the CYP2D6 and CYP2C19 genes that result in decreased enzymatic activity have been documented. Here we describe a patient case of VEN associated palpitations and asthenia. The patient takes VEN extended release 150 mg twice daily. Genotyping confirmed the patient is a poor metabolizer for CYP2D6 and an intermediate metabolizer for CYP2C19. We propose that the palpitations and asthenia are related to sustained VEN exposure due to reduced metabolism.

Pharmacokinetic Pharmacogenetic Prescribing Guidelines for Antidepressants: A Template for Psychiatric Precision Medicine

Antidepressants are commonly prescribed medications in the United States, and there is increasing interest in individualizing treatment selection for more than 20 US Food and Drug Administration-approved treatments for major depressive disorder. Providing greater precision to pharmacotherapeutic recommendations for individual patients beyond the large-scale clinical trials evidence base can potentially reduce adverse effect toxicity profiles and increase response rates and overall effectiveness. It is increasingly recognized that genetic variation may contribute to this differential risk to benefit ratio and thus provides a unique opportunity to develop pharmacogenetic guidelines for psychiatry. Key studies and concepts that review the rationale for cytochrome P450 2D6 (CYP2D6) and cytochrome P450 2C19 (CYP2C19) genetic testing can be delineated by serum levels, adverse events, and clinical outcome measures (eg, antidepressant response). In this article, we report the evidence that contributed to the implementation of pharmacokinetic pharmacogenetic guidelines for antidepressants primarily metabolized by CYP2D6 and CYP2C19.

Clinical association between pharmacogenomics and adverse drug reactions

Adverse drug reactions (ADRs) are a major public health concern and cause significant patient morbidity and mortality. Pharmacogenomics is the study of how genetic polymorphisms affect an individual's response to pharmacotherapy at the level of a whole genome. This article updates our knowledge on how genetic polymorphisms of important genes alter the risk of ADR occurrence after an extensive literature search. To date, at least 244 pharmacogenes identified have been associated with ADRs of 176 clinically used drugs based on PharmGKB. At least 28 genes associated with the risk of ADRs have been listed by the Food and Drug Administration as pharmacogenomic biomarkers. With the availability of affordable and reliable testing tools, pharmacogenomics looks promising to predict, reduce, and minimize ADRs in selected populations.

Accelerated hypertension after venlafaxine usage

Venlafaxine is the first antidepressant that acts via inhibiting serotonin and noradrenaline reuptake. Hypertension is observed in doses exceeding 300 mg/day and is the most feared complication. We report a patient with accelerated hypertension after venlafaxine use observed at a dose of 150 mg/day. A 23-year-old patient with symptoms of insomnia, depression, anhedonia, fatigue admitted our clinic. Venlafaxine at a dose of 75 mg/day was initiated after he was diagnosed with major depressive disorder. After 5 months, venlafaxine dose was uptitrated to 150 mg/day due to inadequate response to drug. After using venlafaxine for ten months at the dose of 150 mg/day, he admitted our clinic with headache and epistaxis. He was hospitalized after his blood pressure was measured as 210/170 mmHg. No secondary causes for hypertension were found, and venlafaxine treatment was considered possible etiologic factor. After stopping venlafaxine treatment, his blood pressure was reverted back to normal limits. While mild elevation of blood pressure could be observed after venlafaxine treatment, this case shows that accelerated hypertension with a diastolic blood pressure rise above 120 mmHg could be observed at relatively low doses of venlafaxine. Close monitoring of blood pressure is necessary after initiation of treatment, as accelerated hypertension could cause endorgan damage with potentially catastrophic results.

Risk of QT/QTc Prolongation Among Newer Non-SSRI Antidepressants

Objective: To review QT prolongation potential with newer nonselective serotonin reuptake inhibitor (non-SSRI) antidepressants. Data Sources: A PubMed literature search was performed from 1982 through June 16, 2014. Search terms included bupropion, desvenlafaxine, duloxetine, levomilnacipran, mirtazapine, venlafaxine, and vilazodone in combination with each of the following terms: cardiac toxicity, QTc prolongation, QT prolongation, torsades de pointes, and TdP. Study Selection and Data Extraction: English-language human studies, case reports, package inserts, manufacturer electronic communications, and ArizonaCert database were utilized. Data Synthesis: Rare QT prolongation has been reported with venlafaxine at therapeutic doses and in overdose. Bupropion has also been linked to QT prolongation in overdose situations. In elderly patients with a variety of high-risk comorbidities, mirtazapine did demonstrate higher odds of sudden cardiac death and ventricular arrhythmias when compared with paroxetine. Largely because of a lack of available data, existing studies fail to demonstrate QT prolongation with desvenlafaxine, duloxetine, levomilnacipran, and vilazodone. Conclusion: Based on the current literature, risk of QT/QTc prolongation with the majority of newer non-SSRI antidepressants at therapeutic doses is low. The highest risk for QT prolongation appears to exist in overdose situations with venlafaxine and bupropion. Given the few to nonexistent controlled studies and confounding variables present in case reports, it is difficult to draw conclusions on QT prolongation risk with many of the newer non-SSRI antidepressants.

Norepinephrine transporter function and human cardiovascular disease

Approximately 80-90% of the norepinephrine released in the brain or in peripheral tissues is taken up again through the neuronal norepinephrine transporter (NET). Pharmacological studies with NET inhibitors showed that NET has opposing effects on cardiovascular sympathetic regulation in the brain and in the periphery. Furthermore, NET is involved in the distribution of sympathetic activity between vasculature, heart, and kidney. Genetic NET dysfunction is a rare cause of the postural tachycardia syndrome. The condition is characterized by excessive adrenergic stimulation of the heart, particularly with standing. Conversely, NET inhibition may be beneficial in hypoadrenergic states, such as central autonomic failure or neurally mediated syncope, which results from acute sympathetic withdrawal. Biochemical studies suggested reduced NET function in some patients with essential hypertension. Furthermore, cardiac NET function appears to be reduced in common heart diseases, such as congestive heart failure, ischemic heart disease, and stress-induced cardiomyopathy. Whether NET dysfunction is a consequence or cause of progressive heart disease in human subjects requires further study. However, studies with the nonselective NET inhibitor sibutramine suggest that reduced NET function could have an adverse effect on the cardiovascular system. Given the widespread use of medications inhibiting NET, the issue deserves more attention.