Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The antidepressant venlafaxine has a unique chemical structure and neuropharmacologic profile. It significantly inhibits reuptake of both serotonin and norepinephrine and lacks notable muscarinic-cholinergic or alpha-adrenergic effects. Premarketing studies involving more than 2000 patients showed the efficacy of venlafaxine to be significantly greater than placebo at dosages between 75 and 375 mg/day in both outpatients and inpatients. The medication may be administered twice or three times daily. Venlafaxine was found equally effective for patients older and younger than 60 years and in those with psychomotor retardation or agitation; it proved slightly more efficacious than fluoxetine in a comparison study with melancholic inpatients. A promising finding of these studies is the suggestion of a rapid onset of clinical effect for venlafaxine. In some studies, venlafaxine showed a consistent and robust clinical superiority over placebo by Week 1, and in the inpatient study involving melancholic patients, the superiority of venlafaxine was demonstrated as early as Day 4. In general, early responses are seen at the higher dosages. Venlafaxine has also shown promise in treating rigorously defined treatment-refractory depression. The adverse effects of venlafaxine that most often led to discontinuation from a clinical study were nausea (6%), somnolence (3%), insomnia (3%), and dizziness (3%). Although nausea was the most common adverse effect overall, it resolved rapidly--within the first 1 to 3 weeks of therapy. Other adverse events with incidences significantly higher than with placebo were dizziness, constipation, sweating, nervousness, and abnormal ejaculation. The seizure rate and potential for cardiac conduction changes or orthostatic hypotension with venlafaxine were comparable with rates seen with the serotonin selective reuptake inhibitors. A small number of patients experienced dose-dependent blood pressure elevation with venlafaxine in premarketing studies (3% to 5% of those receiving < or = 200 mg/day; 7% of those receiving 201-300 mg/day; 13% of those receiving > 300 mg/day vs. 2% receiving placebo). In general, venlafaxine is well tolerated, and its treatment discontinuation rate is similar to those of the newer antidepressants and superior to discontinuation rates with the first-generation agents.
 ...
PMID:The role of venlafaxine in rational antidepressant therapy. 796 45

Major depression is a common and disabling disorder with far-reaching social and economic implications. Nonetheless, major depression is treatable by one of the many currently available antidepressants with response rates of approximately 65-70%. Treatment of depression has improved in recent years because of the availability of effective and well-tolerated antidepressants, such as the selective serotonin reuptake inhibitors (SSRIs). The currently available antidepressants are generally equally effective and are distinguished primarily by side-effect profiles. The side effects of tricyclic antidepressants (TCAs) are attributed to their nonspecific interaction with cholinergic, histaminergic, serotonergic, and dopaminergic receptors in the central nervous system. The secondary amine TCAs, nortriptyline and desipramine, are preferred among the TCAs because of a more favorable side-effect profile. The TCAs are cardiotoxic, and overdoses are frequently fatal. Adverse effects, including potentially fatal drug and food interactions, limit the use of the monoamine oxidase inhibitors (MAOIs); however, these agents have a role in the treatment of depression with comorbid anxiety, refractory depression, atypical depression, and bulimia. The SSRIs possess a class side-effect profile of headache, nausea, and sexual dysfunction. Individual differences in side effects may distinguish fluoxetine (nervousness, restlessness), sertraline (diarrhea, loose stools), and paroxetine (dry mouth). The SSRIs all inhibit certain cytochrome P450 isoenzymes involved in the metabolism of drugs, such as the TCAs, and each SSRI has been reported to increase plasma concentrations of concomitantly administered TCAs. Bupropion therapy is associated with a risk of seizure development, which can be minimized by multiple daily doses. Trazodone is sedating and can rarely cause priapism. The related compound, nefazodone, does not cause sexual dysfunction or priapism, but is associated with sedation. Venlafaxine, a recently available antidepressant that appears to have efficacy in treatment-refractory depression, may cause nausea that requires gradual upward dosage titration. Higher doses of venlafaxine may also cause elevations in blood pressure, heart rate, and serum cholesterol. As more is learned about the pathophysiology of depression, even more specific and well-tolerated antidepressants will be developed.
 ...
PMID:Contemporary management of depression. 799 23

Venlafaxine is a newly introduced antidepressant agent. The drug causes selective inhibition of neuronal reuptake of serotonine and norepinephrine with little effect on other neurotransmitter systems. Cases of seizures, tachycardia, and QRS prolongation have been observed following drug overdose in humans. The clinical manifestations of cardiac toxicity suggest that venlafaxine may exhibit cardiac electrophysiological effects on fast conducting cells. Consequently, studies were undertaken to characterize effects of venlafaxine on the fast inward sodium current (I(Na)) of isolated guinea pig ventricular myocytes. Currents were recorded with the whole-cell configuration of the patch-clamp technique in the presence of Ca(2+) and K(+) channel blockers. Results obtained demonstrated that venlafaxine inhibits peak I(Na) in a concentration-dependent manner with an estimated IC(50) of 8. 10(-6) M. Inhibition was exclusively of a tonic nature and rate-independent. Neither kinetics of inactivation (tau(inac)= 0.652 +/- 0.020 ms, under control conditions; tau(inac)= 0.636 +/- 0.050, in the presence of 10(-5) M venlafaxine; n = 5 cells isolated from five animals) nor kinetics of recovery from inactivation of the sodium channels (tau(re)= 58.7 +/- 1.6 ms, under control conditions; tau(re)= 54.4 +/- 1.8, in the presence of 10(-5) M venlafaxine; n = 10 cells isolated from six animals) were significantly altered by 10(-5) M venlafaxine. These observations led us to conclude that venlafaxine blocks I(Na) following its binding to the resting state of the channel. Thus, the characteristics of block of I(Na) by venlafaxine are different from those usually observed with most tricyclic antidepressants or conventional class I antiarrhythmic drugs.
 ...
PMID:Mechanism of sodium channel block by venlafaxine in guinea pig ventricular myocytes. 1049 Sep 14

Depression in epilepsy patients is not only extremely common, but is often poorly recognized and inadequately treated. Depression can have significant consequences including increased medical utilization, poor quality of life, social disability, and mortality. Etiology of depression is multifaceted with prominent psychosocial determinants. Salient medical issues include iatrogenic causes, especially side effects of antiepileptic drugs (AEDs). In addition, seizures with increased frequency and with "forced normalization" can be associated with mood disturbance. After a thorough search for correctable causes, treatment should not be delayed, and should include both psychotherapy and pharmacologic therapies. Antidepressants remain the mainstay of pharmacologic intervention with the selective serotonin reuptake inhibitors (SSRIs) considered first-line treatment. Venlafaxine, nefazadone, and tricyclic antidepressants (TCAs) can also be used, but with some important caveats. Decreasing the seizure threshold is a common side effect of all antidepressants, but the risk can be minimized and should not prevent vigorous treatment of the depressive state. Other side effects present with varying frequency from the common (eg, sexual dysfunction as seen with SSRIs) to uncommon withdrawal reactions and rare complications of serotonin syndrome. Depression must also be considered a recurring disease, and when a successful regimen is ascertained, adequate continuation of treatment is a necessity. Care must be taken to treat the patient until complete resolution is achieved. Many patients with a major depressive disorder (MDD) will improve with inadequate treatment, but remain encumbered by a smoldering, low-level dysthymia that, in itself, can severely restrict the patient's quality of life.
 ...
PMID:Depression in Individuals with Epilepsy. 1109 81

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.
 ...
PMID:Proconvulsant effects of high doses of venlafaxine in pentylenetetrazole-convulsive rats. 1196 Jan 97

The present study was designed to investigate the effects of venlafaxine, a serotonin and noradrenaline reuptake inhibitor (SNRI), on ethanol withdrawal syndrome in rats. Adult male Wistar rats (187-319 g) were used for the study. Ethanol (7.2%, v/v) was given to rats by a liquid diet for 21 days. Control rats were pair-fed an isocaloric liquid diet containing sucrose as a caloric substitute to ethanol. Venlafaxine (5, 10, 20 and 40 mg/kg) and saline were injected to rats intraperitoneally just before ethanol withdrawal. After the 2nd, 4th and 6th hour of ethanol withdrawal, rats were observed for 5 min, and withdrawal signs that included locomotor hyperactivity, agitation, stereotyped behaviour and wet dog shakes were recorded or rated. A second series of injections was given at the 6th hour after the first one, and rats were then tested for audiogenic seizures. Venlafaxine produced some inhibitory effects on locomotor hyperactivity, stereotypic behaviours and wet dog shakes. However, a two-way anova of the data did not indicate any significant effect. It reduced the incidence of the audiogenic seizures at the 6th hour of ethanol withdrawal. Venlafaxine (20 mg/kg) also prolonged the latency of the seizures significantly. Our results suggest that acute venlafaxine treatment has limited beneficial effects on ethanol withdrawal syndrome in rats.
 ...
PMID:Effects of venlafaxine on ethanol withdrawal syndrome in rats. 1554 41

Venlafaxine is a recently developed serotoninergic antidepressant whose reported toxicity at overdose levels includes central nervous system depression, seizures, and cardiovascular toxicity. The authors now present a case of venlafaxine overdose in a young woman complicated by a rise in plasma creatine kinase activity up to 52,600 U/L. Immediate therapy with intravenous fluids, bicarbonate, and furosemide was administered, and there were no further complications, notably no renal failure. This case supports the notion that venlafaxine can induce direct skeletal muscle toxicity leading to severe rhabdomyolysis. Therefore, clinicians should monitor muscle enzymes in patients with venlafaxine overdose to detect the development of rhabdomyolysis at an early stage and to initiate appropriate therapy rapidly.
 ...
PMID:Severe rhabdomyolysis following venlafaxine overdose. 1617 26

Venlafaxine (Efexor), a selective noradrenergic reuptake inhibitor, is an important therapeutic option in the treatment of perinatal depression, but its effects on the newborn are uncertain. We present a report of two infants with neonatal seizures attributed to maternal use of venlafaxine. The first infant was hypotonic and required resuscitation at birth. The second was born in a good condition but developed clinically apparent seizures after the second day of life. Both infants responded rapidly to treatment with phenobarbitone that was weaned uneventfully by the first and second week of life. Both remain well at 1 year of age. Other causes of neonatal seizures were excluded and neurological investigations on these two infants were unremarkable. We suggest that all infants exposed to maternal venlafaxine, no matter their condition at birth, be monitored in hospital for at least 3 to 4 days in order to preempt and treat adverse neurological events.
 ...
PMID:Neonatal seizures from in utero venlafaxine exposure. 1704 5

Rhabdomyolysis has been reported after venlafaxine ingestion. We wished to characterize the prevalence of this adverse effect in a realistic clinical setting. Therefore, a retrospective casenote review was performed, including 235 patients admitted to the Royal Infirmary of Edinburgh due to venlafaxine overdose between January 2000 and June 2006. Seizures occurred in 8.9% of the study population. Patients who suffered seizures had ingested larger quantities of venlafaxine than those who did not develop seizures; median (interquartile range) 2800 mg (2006-4350 mg) versus 1500 mg (900-2700 mg, p = 0.001). Raised CK values were more prevalent in those with seizures than those without seizures (61.1% versus 25.7% respectively, p = 0.004). Nonetheless, a positive correlation was found between the quantity of venlafaxine ingested and CK across the whole group (rho = 0.201, 95% confidence interval 0.045-0.347), and in patients who had not developed seizures (rho = 0.174, 95% confidence interval 0.009-0.331). Venlafaxine overdose is associated with a high prevalence of acute muscle injury, both in patients who develop seizures and in those who do not. The clinical significance of this association merits further consideration.
 ...
PMID:Venlafaxine ingestion is associated with rhabdomyolysis in adults: a case series. 1732 98

Venlafaxine is a relatively new antidepressant with selective effects. Compared with traditional antidepressants, this agent has fewer adverse side effects. However, venlafaxine overdose has been reported with severe complications such as seizure, ventricular tachycardia, serotonin syndrome, neuroleptic malignant syndrome and rhabdomyolysis. We present a 21-year-old female with bipolar depression who took a low dose of venlafaxine, but subsequently developed severe rhabdomyolysis. Her plasma level of creatine kinase increased up to 18,711 U/L in few days. These findings may serve as a reminder to physicians to be alert to the possibility of rhabdomyolysis in patients who have only taken a low dose of venlafaxine.
 ...
PMID:Low-dose venlafaxine-induced severe rhabdomyolysis: a case report. 2245 96


1 2 Next >>