The safety and tolerability of venlafaxine hydrochloride: analysis of the clinical trials database

Hepatitis associated with low-dose venlafaxine for postmenopausal vasomotor symptoms

OBJECTIVE

To report a case of drug-induced hepatitis associated with low-dose venlafaxine.

CASE SUMMARY

A 60-year-old white woman receiving venlafaxine 75 mg daily for vasomotor symptoms presented after one month of therapy with nonspecific complaints, including abdominal pain. A series of diagnostic and laboratory tests revealed an enlarged liver and elevated alanine aminotransferase (ALT) up to 372 U/L, aspartate aminotransferase (AST) up to 99 U/L, gamma-glutamyltransferase (GGT) up to 962 U/L, and alkaline phosphatase up to 758 U/L. All potential hepatotoxic medications were discontinued. Within one week after stopping venlafaxine, her liver function test results showed marked improvement. Almost 4 weeks after discontinuing therapy, venlafaxine 37.5 mg was reinitiated. Her ALT, AST, GGT, and alkaline phosphatase again increased to 269, 49, 256, and 263 U/L, respectively, 6 days after resuming therapy. Upon discontinuation of venlafaxine, her liver function abnormalities resolved.

DISCUSSION

This case is significant due to the severity of symptoms and consequent liver function test results involved in diagnosing drug-induced hepatitis. It is also remarkable because of the hepatotoxicity that occurred initially and on rechallenge with low-dose venlafaxine. The hepatotoxic effects of venlafaxine have been characterized as rare and idiosyncratic. The Naranjo probability scale revealed that the adverse drug event was probable.

CONCLUSIONS

Venlafaxine therapy can lead to drug-induced hepatitis, even when used at low doses. Clinicians should be aware of this possible adverse effect of venlafaxine therapy and monitor patients closely after initiation of therapy.

Venlafaxine and Bladder Function

BACKGROUND

Occasional case reports describe urinary incontinence in patients taking the selective serotonin and norepinephrine reuptake inhibitor antidepressant venlafaxine.

OBJECTIVE

In this study the authors investigated the possible effect of venlafaxine on urinary function in a series of 9 patients with urinary retention resulting from spinal cord lesions. They primarily sought to understand whether the reported venlafaxine-induced urinary incontinence was a specific drug-induced effect and, if so, whether venlafaxine might be an effective treatment of urinary retention.

METHODS

During a 1-week baseline period, patients measured postvoiding residual volume through a catheter and recorded the number of micturitions within 24 hours. At the end of the baseline period, venlafaxine 75 mg extended-release on a once-daily evening administration schedule was added to their therapy for 1 week.

RESULTS

None of the patients reported severe/uncontrollable side effects while taking venlafaxine. Extended-release venlafaxine (75 mg/day) significantly reduced the postvoiding residual volume and increased the micturition rate; the volume diminished on the first day of treatment and remained stable over the ensuing days.

CONCLUSION

These findings suggest that venlafaxine could be useful to improve voiding in patients with spinal cord disease.

Combined effects of venlafaxine, nicotine replacement, and brief counseling on smoking cessation

In this study, 147 smokers were randomly assigned to receive either venlafaxine or placebo in conjunction with behavioral counseling (9 weekly sessions) and transdermal nicotine replacement therapy (22 mg/day). Patients began medication 2 weeks before quitting and continued for 18 weeks after quitting, with the daily dose titrated from 150 to 225 mg. in response to symptoms of negative affect and relapse. The results showed no main effect of treatment on abstinence. Post hoc analysis revealed that both at the end of treatment and at the 1-year follow-up smokers consuming less than a pack of cigarettes a day benefited from the addition of venlafaxine to the treatment regimen. Venlafaxine also reduced negative affect for all smokers for up to 6 weeks postcessation. The findings suggest that venlafaxine could have some role to play in the treatment of lighter smokers, in addition to the expected benefits of nicotine replacement therapy and behavioral counseling.

Clinical trials of potential antidepressants: to what extent are the elderly represented: a review

BACKGROUND

There is widespread use of antidepressants in the elderly population. The principle of treatment of depression, however, is derived mostly from studies employing young adults and healthy elderly. This article reviews the literature on the extent to which the elderly are represented in clinical trials of potential antidepressants.

METHOD

Medline search of relevant articles of clinical trials of potential antidepressants.

RESULTS

The maximum age of inclusion for most clinical trials was 65 years. The highest age reported for depressed subjects was 90 years. There was no clear consensus on who were considered to be elderly; clinical trials conducted on the elderly included subjects who were 50, 55, or 60 years and over. Pharmacological studies on healthy subjects were most often done on young adults, age range 18 to 65 years. The period of study was relatively shorter for clinical trials done on elderly subjects. There was however, no difference in the exclusion or inclusion criteria between studies done in young and elderly subjects.

CONCLUSIONS

Elderly subjects aged 75 years and over were clearly underrepresented in the clinical trials of potential antidepressants. For drugs that are used by the elderly, in its pivotal studies for registration, the inclusion of at least 25% of subjects aged 75 years and over is recommended.

Extended-release venlafaxine in relapse prevention for patients with major depressive disorder

Many studies have demonstrated that venlafaxine is an efficacious and safe treatment for major depressive disorder (MDD). This double-blind, placebo-controlled study was performed to evaluate the efficacy of venlafaxine extended-release (XR) (75-225 mg/day) in the prevention of relapse of depression. Patients with MDD who responded to an 8-week course of venlafaxine XR treatment, i.e., had a score < or = 3 on the Clinical Global Impressions scale-Severity of Illness item (CGI-S) and a 21-item Hamilton Rating Scale for Depression (HAM-D(21)) score < or = 10, were randomly assigned to receive continuation treatment (up to 6 months) with venlafaxine XR (n=161) or placebo (n=157). The main efficacy outcome measure was the number of patients who experienced a relapse of depression. Relapse was defined by either a combination of a patient meeting Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for MDD and a CGI-S score > or = 4, two consecutive CGI-S scores > or = 4, or a final CGI-S score > or = 4 for a patient who withdrew from the study. The cumulative probability of relapse was calculated using the Kaplan-Meier method of survival analysis. During the 6-month evaluation period, significantly more patients in the placebo group had a relapse of MDD than did patients who continued treatment with venlafaxine XR. Cumulative relapse rates at 3 and 6 months were 19 and 28%, respectively, for venlafaxine XR, and 44 and 52%, respectively, for placebo. This study demonstrates that venlafaxine XR is an effective and safe continuation therapy.

A review of antidepressant-induced hypomania in major depression: suggestions for DSM-V

OBJECTIVES

To determine if the classification of 'antidepressant-induced hypomania' in DSM-IV is supported by available data.

METHODS

We reviewed the available scientific literature to examine the incidence of mania and hypomania in non-bipolar patients who were treated with antidepressants.

RESULTS

Eighty-nine per cent of studies of antidepressants in major depressive disorder patients reported no cases of treatment-induced hypomania. No instances of treatment-induced hypomania were reported in three large studies of patients with chronic forms of depression.

CONCLUSIONS

The rate of antidepressant-induced hypomania in major depressive disorder is within the rate of misdiagnosis of bipolar depression as unipolar. Depressed patients who experience antidepressant-associated hypomania are truly bipolar.

Fatality Related to a 30-g Venlafaxine Overdose

A 30-g venlafaxine overdose resulted in death for a 39-year-old woman whose 43-day clinical course was highlighted by refractory hypotension and the resulting complications of bowel ischemia and perforation. Her venlafaxine and O-desmethylvenlafaxine levels, analyzed by high-performance liquid chromatography one day after ingestion, were 21.82 mg/L (therapeutic range 0.1-0.5 mg/L) and 3.33 mg/L (0.2-0.4 mg/L), respectively. These levels remained elevated for over 7 days. Postulated explanations for these extended elevated levels were saturation of drug metabolism, decreased drug metabolism, and existence of a genetic polymorphism. Our patient's venlafaxine overdose produced a wide variety of clinical challenges, to include seizures, tachycardia, decreased level of consciousness, refractory hypotension, and bowel dysmotility. In addition, this case augments the growing body of literature that suggests that venlafaxine may be fatal in overdose situations.

A double blind comparison of venlafaxine and paroxetine in obsessive-compulsive disorder

While the usefulness of clomipramine and selective serotonin reuptake inhibitors (SSRIs) in obsessive-compulsive disorder (OCD) has been established, the efficacy of serotonin-norepinephrine reuptake inhibitors remains to be determined. This report describes the first randomized double-blind comparison study of an SNRI in patients with obsessive-compulsive disorder. The current study compares the efficacy and tolerability of venlafaxine with paroxetine. One hundred and fifty patients with primary OCD according to DSM-IV criteria were randomly assigned in a 12-week double-blind trial to receive dosages titrated upward to 300 mg/d of venlafaxine (n = 75) or 60 mg/d of paroxetine (n = 75). Primary efficacy was assessed by the change from baseline on the Yale-Brown obsessive-compulsive scale (Y-BOCS). Other assessments throughout the trial included the Hamilton depression rating scale, and the Hamilton anxiety rating scale. An intent-to-treat, last-observation-carried-forward analysis demonstrated a mean decrease on the Y-BOCS of 7.2 +/- 7.5 in the venlafaxine group and of 7.8 +/- 5.4 in the paroxetine group. In both treatment groups, a responder rate (decrease > 35% on the Y-BOCS) of approximately 40% was found. There were no significant differences between venlafaxine and paroxetine with regard to response or responder rates. The incidence of adverse events for venlafaxine and paroxetine was comparable. The most common side effects for venlafaxine were somnolence, insomnia, a dry mouth, and sweating; and for paroxetine somnolence, sweating, nausea, and headache. These results show that venlafaxine was equally effective to paroxetine in treating patients with OCD. Venlafaxine may be a useful therapy for obsessive-compulsive patients, but is not superior to SSRIs.

Venlafaxine: A 2003 update

BACKGROUND

venlafaxine has been available for use as an antidepressant in the United States for a decade.

OBJECTIVE

Comprehensive reviews of venlafaxine have been published elsewhere; thus, this update focuses on newer issues of treatment remission in depression, treatment-resistant depression, and extended-release venlafaxine for generalized anxiety disorder (GAD).

METHODS

Relevant clinical literature from 1993 through 2003 was identified from database searches of MEDLINE and International Pharmaceutical Abstracts, and from manual searches of reference lists of the identified papers. Search terms included venlafaxine extended-release, venlafaxine XR, treatment-resistant depression, depressive disorders, anxiety disorders, generalized anxiety disorder, and antidepressive agents second generation.

RESULTS

With its dual action of serotonin and noradrenergic reuptake inhibition, venlafaxine has been shown to be superior in efficacy to selective serotonin reuptake inhibitors for severe major depressive disorder, treatment-resistant depression, and depressive symptom remission. Its demonstrated efficacy for both short- and long-term treatment of GAD has led to its use for obsessive-compulsive disorder and chronic pain syndromes, although inadequate clinical literature currently exists to support these latter 2 uses. In the past decade, no new or unexpected adverse events have been identified with venlafaxine therapy, except a possibly greater risk of fatal overdose compared with other serotonergic drugs, suggesting the need for caution in patients with suicidal ideation. Because venlafaxine is a potent serotonin agonist, caution must also be exercised to prevent the possibility of serotonin syndrome when used with other serotonin agonists, and its dose should be tapered very gradually to minimize the risk of a serotonin withdrawal reaction.

CONCLUSION

Venlafaxine has emerged as a successful post-SSRI-era antidepressant with an expanded range of uses since it was first marketed.

Tender points as predictors of distress and the pharmacologic management of fibromyalgia syndrome

The object of this study was to determine the association between tender point pain ratings, tender point counts and distress in people with fibromyalgia and to review the pharmacotherapy of fibromyalgia. Demographic, psychosocial, and health status information was collected from 316 health maintenance organization members with fibromyalgia. A manual tender point exam was conducted. Tender point counts predicted 3.0%, and tender point severity ratings predicted 8.3%, of the variance in distress. Little difference was found between the variance predicted for physical versus psychologic distress. A principal components analysis of all measures produced four distinct factors: global-physical functioning, tender points, psychologic, and physical. Tender point pain ratings and counts predicted a small but significant amount of variance in distress. In addition, FMS involves at least four rather distinct factors, one of which is related to tender points. Pharmacotherapeutic management is provided on a patient-specific basis including pharmacokinetics, pharmacodynamic, pathophysiologic, and psychosocial needs designed and modulated for each individual patient.

Efficacy of venlafaxine in major depression resistant to selective serotonin reuptake inhibitors

INTRODUCTION

Some studies suggest that venlafaxine, due to its pharmacodynamic characteristics, could be an effective drug in depression, resistant to other antidepressive agents. This investigation explores the efficacy and tolerability of venlafaxine in major depression, resistant to a selective serotonin reuptake inhibitor (SSRI).

METHODS

A multicenter naturalistic study was performed during 6 months and included those patients diagnosed of major depression according to the criteria of DSM-IV who had a minimum score of 18 on the Hamilton Depression Rating Scale (HAM-D) and who had not responded to previous treatment with a SSRI at therapeutic doses for a minimum of 4 weeks. The assessment of efficacy was performed with the HAM-D scale, the Montgomery-Asberg Depression Rating Scale (MADRS), the Hamilton Anxiety Rating Scale (HAM-A) and the Global Clinical Impression (GCI). Tolerability was evaluated by recording the adverse reactions and with the GCI score on overall drug tolerability.

RESULTS

A total of 69 patients, of which 59 were evaluable for efficacy (they had fulfilled at least 4 weeks of treatment), were included. About 81% of all of them obtained a reduction of at least 50% in the HAM-D, 74% were considered as "quite improved" or "very improved" in the GCI and 69% met both criteria. The mean dose of venlafaxine used was 170.4 (S.D.=43.8) mg. Of the 21 patients who did not complete the 6 months of treatment, 3 were due to lack of efficacy, 6 due to adverse effects and 12 for other reasons. About 89.2% of side effects were considered as mild or moderate.

CONCLUSION

The results of our study support the efficacy and tolerability of venlafaxine in patients suffering from depression who have not responded to SSRI treatment.

Venlafaxine poisoning complicated by a late rise in creatine kinase: two case reports

Newer anti-depressants are often considered to be safer than more established anti-depressants. However, clinical experience of the effects of these agents in overdose is limited. Here, we present two cases of venlafaxine overdose that were complicated by a delayed rise in plasma creatine kinase. Although the clinical consequences were not serious, physicians should be alerted to the possibility of delayed rhabdomyolysis or serotonin syndrome in patients who have taken venlafaxine in overdose.

An organic psychosis due to a venlafaxine-propafenone interaction

OBJECTIVE

An extraordinary case of an organic psychosis during the treatment of a patient with a bipolar affective disorder.

METHODS

Clinical observation and further investigations including monitoring of serum levels (case report).

RESULTS

A significant interaction between venlafaxine and propafenone causes markedly increased serum levels of venlafaxine correlating with unexpected psychopathological changes.

CONCLUSIONS

There is a potentially dangerous interaction between venlafaxine and propafenone. Serum levels of venlafaxine should be monitored if propafenone is added.

Proconvulsant effects of high doses of venlafaxine in pentylenetetrazole-convulsive rats

Venlafaxine, an atypical antidepressant drug, has been used to treat several neurological disorders, presenting excellent efficacy and tolerability. Clinical seizures after venlafaxine treatment have occasionally been reported when the drug was used at very high doses or in combination with other medications. The aim of the present study was to investigate the convulsant effects of venlafaxine in rats under controlled laboratory conditions. Adult male Wistar rats (8 per group) receiving venlafaxine or saline at the doses of 25-150 mg/kg were subjected 30 min later to injections of pentylenetetrazole at the dose of 60 mg/kg. The animals receiving 75, 100 and 150 mg/kg venlafaxine presented increased severity of convulsion when compared to controls (P = 0.02, P = 0.04, and P = 0.0004, respectively). Indeed, an increased percentage of death was observed in these groups (50, 38, and 88%, respectively) when compared to the percentage of death in the controls (0%). The group receiving 150 mg/kg showed an reduction in death latency (999 +/- 146 s) compared to controls (1800 +/- 0 s; cut-off time). Indeed, in this group, all animals developed seizures prior to pentylenetetrazole administration. Surprisingly, the groups receiving venlafaxine at the doses of 25 and 50 mg/kg showed a tendency towards an increase in the latency to the first convulsion. These findings suggest that venlafaxine at doses of 25 and 50 mg/kg has some tendency to an anticonvulsant effect in the rat, whereas doses of 75, 100 and 150 mg/kg presented clear proconvulsant effects in rats submitted to the pentylenetetrazole injection. These findings are the first report in the literature concerning the role of venlafaxine in seizure genesis in the rat under controlled conditions.

Efficacy of venlafaxine in geriatric depression

Geriatric patients with major depression present clinical challenges not encountered in younger individuals, including a greater incidence of medical comorbidity, higher rates of multiple medication use, changes in drug metabolism due to age or physical illness, and increased sensitivity to antidepressant side effects. Nevertheless, successful treatment of depressive disorders in the elderly improves mental and physical functioning, decreases morbidity and perhaps mortality, and enhances quality of life. Recent research indicates that newer antidepressants are effective for late life depression and safer for older individuals. Among newer antidepressants, venlafaxine has a pharmacological profile that makes it an attractive choice for geriatric patients. It has limited potential to interact with other medications because it only weakly inhibits the cytochrome P450 system and binds to plasma proteins at a low level. Dosing may have to be adjusted for patients with renal failure, but typically not for those with liver disease or other medical conditions. Data from three double-blind and four open clinical trials support the safety and efficacy of venlafaxine for geriatric depression. Patients may experience transient, generally tolerable side effects such as insomnia, nausea, agitation, or dry mouth early in treatment, but more serious problems such as falls or cardiac rhythm disturbances seem to be rare. Treatment emergent hypertension occurs in a small percentage of older patients, generally at doses above 150 mg/day. Finally, emerging data suggest that venlafaxine may be effective for conditions such as stroke, anxiety, and neuropathic pain that frequently accompany depressive disorders in the elderly.

Neuropharmacology of venlafaxine

Venlafaxine (Effexor) is an effective antidepressant and has also been approved for the treatment of generalized anxiety disorder. Venlafaxine was initially characterized as an inhibitor of both serotonin (5HT) and norepinephrine (NE) uptake and was therefore termed a "dual uptake inhibitor." This chapter reviews data from both in vitro and in vivo studies regarding its effects on 5HT and NE neurotransmission. In addition, the effects of venlafaxine on other systems that may play a role in its therapeutic efficacy effects are described. The data indicate that venlafaxine is a relatively weak inhibitor of NE transport in vitro. In vivo studies indicate that venlafaxine selectively inhibits 5HT uptake at low therapeutic doses and inhibits both 5HT and NE uptake at higher therapeutic doses. This chapter concludes with a discussion of the effects of venlafaxine on various aspects of physiology.

Efficacy of venlafaxine in the treatment of severe depression

Although the efficacy of available antidepressants has been well established in the treatment of mild to moderate depression, clinical research literature on severe depression is more limited, due to lack of a standardized definition for the condition and the resulting inconsistent data. Given the heterogeneous nature of severe depression, reports suggesting noradrenergic as well as serotonergic system involvement in depressive disorders, and the substantive capability of both clomipramine and TCA-SSRI combination to treat severe depression, investigation of dual-action antidepressant agent efficacy in the treatment of severe depression is warranted. The merit of one such combined-action agent, venlafaxine, is reviewed. Efficacy findings from the limited number of comparative clinical trials conducted in the severely depressed patient population suggest that, while venlafaxine has been evaluated in a broad range of depressed patients, this compound may be particularly effective for the severely ill. Pharmacological features of venlafaxine, which may benefit the patient with severe depression, include the possibility of a rapid onset of action and a dose-response curve. Based upon studies comparing venlafaxine with both placebo and other first-line antidepressants, it is concluded that venlafaxine is safe, tolerable, and effective for the treatment of severe depression.

Seizures associated with therapeutic doses of venlafaxine and trimipramine

OBJECTIVE

To report a patient having a first-time seizure after receiving venlafaxine and trimipramine for depression.

CASE SUMMARY

A 25-year-old white woman with chronic depression was treated with venlafaxine 150 mg/d and trimipramine 50 mg/d. Eleven days after increase of the trimipramine dosage to 100 mg/d, she was hospitalized because of seizures suggesting a secondary generalized grand-mal episode. The electroencephalogram showed a pathologic pattern with several generalized epileptiform discharges. Because of suspected drug-induced seizures, both antidepressants were stopped. After antidepressant drug cessation, the patient was symptom free and had no further seizure episodes within the following 12 months of follow-up. No other potential cause for the seizure episode could be identified.

DISCUSSION

Both venlafaxine and trimipramine have been associated with seizures, mainly after overdose. Venlafaxine-associated seizures at therapeutic doses have not been reported in the literature. We hypothesize that a pharmacodynamic or pharmacokinetic drug interaction between venlafaxine and trimipramine involving the CYP2D6 isoenzyme may have played a role in inducing the seizures.

CONCLUSIONS

Clinicians should be aware of the proepileptogenic effect of venlafaxine and trimipramine at therapeutic doses and that this combination may eventually increase the risk of seizures.

Pharmacotherapeutic options in the treatment of comorbid depression and anxiety

Although anxiety and mood disorders are listed as separate disorders in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, they frequently coexist. They may be expressed phenotypically as comorbidities or as the provisional entity mixed anxiety-depressive disorder. Patients with both anxiety and depression are more symptomatic, use more health care resources, and have a worse prognosis than those with a single disorder. Recognizing and treating these patients are challenges for physicians because the symptoms of the two disorders often overlap. Administration of effective treatment, comprising both anxiolytic and antidepressant effects, can reduce patient distress and disability, as well as inappropriate utilization of medical services. Medications such as tricyclic antidepressants, selective serotonin reuptake inhibitors, nefazodone, venlafaxine XR (extended release) and mirtazapine, are highly effective in treating comorbid depression and anxiety. These newer agents now represent the pharmacotherapeutic treatments of choice for the comorbid conditions.

Antidepressants, old and new. A review of their adverse effects and toxicity in overdose

The newer antidepressants are as efficacious as the older agents in the treatment of depression. They have a side effect profile that is different from the older drugs and are generally better tolerated. Drug-drug interactions do exist with some of these agents and can usually be predicted from knowledge of their metabolism. When taken in overdose as the sole agents they are rarely fatal; seizures, nausea, vomiting, decreased level of consciousness, and tachycardia are common. In combination with other drugs, toxicity can be more severe. The serotonin syndrome can occur with many of these drugs, and the emergency physician must be vigilant in the evaluation of the overdose patient. CAs and older MAOIs are still in use and remain dangerous when taken in overdose. Patients asymptomatic after a period of observation in the ED usually can be discharged after psychiatric evaluation, when it is required.

Cardiovascular and neurological toxicity of venlafaxine

1. We report a case of venlafaxine overdose and describe pharmacokinetic data on drug disposition. 2. Case report. Serial venlafaxine levels were measured and drug half-life calculated and compared to data at therapeutic concentrations. Metabolite concentrations were also measured and the potential for toxicity described with reference to individual variation in such metabolism 3. Venlafaxine can cause significant cardiac and neurotoxicity. Its potential for causing such toxicity may be dependent on whether an individual has the extensive metaboliser cytochrome CYP2D6 phenotype or the poor metaboliser phenotype