ABCB1 gene polymorphisms are associated with fatal intoxications involving venlafaxine but not citalopram.

P-glycoprotein (P-gp), encoded by the ABCB1/MDR1 gene, is a drug transporter at the blood-brain barrier. Several polymorphisms in the ABCB1 gene are known to affect the activity and/or expression of P-gp, thereby influencing the treatment response and toxicity of P-gp substrates like citalopram and venlafaxine. In this study, we aimed to investigate the frequency of ABCB1 genotypes in forensic autopsy cases involving these two antidepressants. Further, the distribution of ABCB1 genotypes in deaths related to intoxication was compared to cases not associated to drug intoxication. The study included 228 forensic autopsy cases with different causes and manners of deaths. The ABCB1 single nucleotide polymorphisms (SNPs) G1199A, C1236T, C3435T and G2677T/A for these individuals were determined. The SNPs C1236T and C3435T in venlafaxine-positive cases were significantly different between the intoxication cases and non-intoxications. This was not seen for cases involving citalopram, indicating that the effect of genetic variants might be substrate specific. This novel finding should, however, be confirmed in future studies with larger number of cases.

The effect of decontamination procedures on the pharmacodynamics of venlafaxine in overdose.

AIMS: To investigate the relationship between decontamination procedures and seizure events caused by venlafaxine overdose and to estimate the time at which 90% of patients would have had their first seizure in the presence and absence of decontamination. METHODS: Data were collected from 319 patients who took an overdose of venlafaxine on 436 occasions. Seizures occurred on 24 of 436 occasions (5%). Patients received one of single dose activated charcoal (SDAC), whole bowel irrigation (WBI), a combination of either (SDAC/WBI) or no decontamination. Logistic regression and time to event analysis were used to investigate the influence of dose and decontamination on the probability of seizures and time to 90% (t(90) ) of seizure, respectively. RESULTS: A linear logistic regression model described the data. Simulation from the model showed that the probability of seizure was 0.05 (0.03-0.08), 0.19 (0.09-0.35) and 0.75 (0.30-0.96) at 1000, 5000 and 10 000 mg, respectively (median and 95% credible interval). At the mean dose of 2100 mg the odds ratios (OR) in the presence of SDAC, WBI and SDAC/WBI were 0.48 (0.25-0.89), 0.71 (0.35-1.22) and 0.25 (0.08-0.62), respectively. A modified Gompertz model described the time to seizure events. Simulations from the Gompertz model showed that the t(90) values for first seizure was 26 h and was not affected by dose or decontamination procedure. CONCLUSION: SDAC/WBI provided greater benefits than the sum of the independent effects of SDAC and WBI. Patients should be observed for at least 24 h for seizures based on the dose and risk of seizure occurring.

Fatal venlafaxine poisonings are associated with a high prevalence of drug interactions.

Venlafaxine (VEN) is an antidepressant found to possess a higher fatal toxicity index (FTI, i.e., deaths in proportion to consumption) than other newer antidepressants and selective serotonin reuptake inhibitors (SSRIs). The aim of this study was to elucidate using post-mortem cases whether the apparent high toxicity of VEN is associated with adverse drug interactions, pharmacogenetic factors and/or the manner of death. Within a 2-year period, a comprehensive post-mortem database and death certificates were searched for cases with laboratory findings of VEN, findings of other drugs, associated background information and the cause and manner of death. In 123 cases, the concentrations of VEN and its two metabolites, O-desmethylvenlafaxine (O-VEN) and N-desmethylvenlafaxine (N-VEN), and the CYP2D6 genotype were determined in post-mortem blood. The median concentrations of VEN, O-VEN and N-VEN were 560, 420 and 49 µg/l, respectively. A prominent feature of the VEN-positive cases was the high abundance of interacting drugs (46%), being more common with higher VEN concentrations. Compared to other common antidepressants, VEN-positive cases showed the highest suicide frequency, but also the proportion of suicidal VEN poisonings of all suicides was substantially higher than that of mirtazapine or SSRIs. Relative CYP2D6 activity did not predispose to high VEN concentrations, and the frequency of the extreme phenotypes followed the general population. In conclusion, the high suicide potential of VEN in combination with the high prevalence of drugs causing adverse interactions could be the reason for the observed high FTI.

Cognitive deterioration after venlafaxine overdose.

BACKGROUND: Venlafaxine is an antidepressant whose adverse event profile is similar to that of the SSRIs (selective serotonin reuptake inhibitors). Serious complications due to venlafaxine overdose have been described. These generally have been resolved with supportive measures alone. However, although patients usually recover even after massive intake of the drug, death may occur in rare cases. OBJECTIVE: This article reports a case of dementia after an overdose of venlafaxine. CASE REPORT: We present a case of severe cognitive deterioration in a 48-year-old woman after venlafaxine overdose in a suicide attempt. She became comatose after the overdose. On recovery from the coma, she suffered irreversible motor and cognitive alterations and seizures. Several factors could justify the possible association of these side effects with venlafaxine overdose: time relationship, severe focal deficit and other neurological signs, symptomatic fluctuation, relationship of serotonin networks with the cognitive functions and deficits related to the network damage, and the potential capacity of venlafaxine to damage the central nervous system. However, other alternatives, especially factors that could implicate a hypoxic encephalopathy as the origin of the dementia, cannot be entirely ruled out. CONCLUSION: Venlafaxine seems to have special toxicity vis-à-vis the SSRIs, and this case adds to the literature supporting this. Cognitive function should be monitored after an overdose with venlafaxine.

[Serotonin syndrome in the course of drug-poisoning--case presentation]. / Zespól serotoninergiczny w przebiegu zatrucia lekami--opis przypadku.

UNLABELLED: Serotonin syndrome is caused by excess serotonin in the central nervous system. It usually occurs as adverse drug-therapy (neuroleptic agents, monoamine oxidase inhibitors, serotonin reuptake inhibitors and others). CASE PRESENTATION: a 50-year-old woman with a history of depression, was admitted to our hospital, due to suicidal drug poisoning (moclobemide- 4500 mg, venlafaxine 1050 mg, mianserin 300 mg and cytisine 30mg). She was also drunk. The patient was unconscious and sweaty, on the ECG tachycardia (120/min) was observed. In addition, several hours after admission, the patient developed acute respiratory failure, we observed myoclonus, lockjaw, body temperature increased to 37.3 degrees Celsius, and blood pressure was 170/80 mmHg. During the neurological examination there was a tendency to bilaterall Babinski sign and the nystagmus was present. The patient was intubated, and we started an intravenous infusion of Relanium. In laboratory studies: ethanol: 2.52 g/l, tests for benzodiazepines and tricyclic antidepressants were negative, WBC 13.1 tys/microl, CPK was elevated to 372 U/L, other parameters (electrolytes, transaminases, serum total protein, glucose, CRP, creatinine) were normal. The patient required intensive care and treatment during the next two days. The diagnosis of serotonin syndrome was based on the Hunter's criteria, which are more sensitive and more specific than Sternbach's criteria. The patient was discharged from hospital in good condition.

Evaluation of a QT nomogram for risk assessment after antidepressant overdose.

AIMS: A QT-heart rate nomogram has recently been proposed as a means of identifying patients at risk of torsades de pointes after antidepressant overdose, based on published cases of drug-induced torsades de pointes. The present study sought to examine the performance of the nomogram in patients who ingest an antidepressant overdose but do not develop arrhythmia. METHODS: A retrospective case control study of patients presenting to hospital after overdose of citalopram, mirtazapine and venlafaxine was carried out. The primary outcome variable was QT higher than the nomogram, and was compared with occurrence of QT(c) (QT corrected by Bazett's formula) greater than ≥440 ms and QT(c) ≥500 ms, with comparison between drugs. Data are expressed as proportions in each group with 95% confidence intervals. RESULTS: There were 858 electrocardiograms from 541 patients. QT was higher than the nomogram in 2.4% (1.4, 4.1%), whereas QT(c) was ≥440 ms in 23.1% (95% CI 19.8, 26.8%), and QT(c) was ≥500 ms in 1.1% (0.5, 2.5%). Citalopram overdose was more likely to be associated with QT higher than the nomogram compared with the other agents (difference 7.0%, 95% CI 2.9, 11.9%, P = 0.001) and more likely to be associated with QT(c) ≥440 ms (difference = 11.0%, 95% CI 2.6, 19.0%, P = 0.013). CONCLUSIONS: The QT nomogram was associated with a lower false positive rate than widely accepted QT(c) criteria, and allowed detection of different effects of individual drugs. The nomogram offers potential advantages over QT(c) criteria and merits further investigation in a clinical setting.

[Acute lethal poisoning with venlafaxine]. / Ostre, smiertelne zatrucie wenlafaksyna.

The case of acute venlafaxine poisoning with fatal outcome is shown. The 52-year-old woman with depression disorder ingested 56 pills of Symfaxin ER 150 venlafaxine as a suicidal attempt. Initially she was observed in the Neurology Department because of seizures, but after her husband found empty packages of medicine she was sent to the Toxicology Department being suspected of venlafaxine poisoning. The qualitative toxicological test confirmed the presence of venlafaxine in urine. In the course of poisoning rhabdomiolysis, hypotension and consecutive acute renal failure were observed. Finally, severe ventricular tachyarrhythmia occurred leading do cardiac arrest. Despite intensive symptomatic and supportive treatment the patient died.

Electrocardiogram changes and arrhythmias in venlafaxine overdose.

AIMS: To investigate serial electrocardiogram (ECG) parameters, haemodynamic changes and arrhythmias following venlafaxine overdose. METHODS: The study included 369 venlafaxine overdoses in 273 patients presenting to a toxicology unit where an ECG was available. Demographic information, details of ingestion, haemodynamic effects [heart rate and blood pressure (BP)] and complications (arrhythmias and conduction defects) were obtained. ECG parameters (QT, QRS) were measured manually and analysed by visual inspection, including plotting QT-HR pairs on a QT nomogram. RESULTS: The median ingested dose was 1500 mg [interquartile range (IQR) 600-3000 mg; range 75-13 500 mg). Tachycardia occurred in 54% and mild hypertension (systolic BP >140 mmHg) in 40%. Severe hypertension (systolic BP >180 mmHg) and hypotension (systolic BP <90 mmHg) occurred in 3% and 5%, respectively. No arrhythmias occurred based on continuous telemetry, and conduction defects were found in only seven of 369 admissions; five of these conduction defects were pre-existing abnormalities. In 22 admissions [6%, 95% confidence interval (CI) 4-10] there was an abnormal QT-HR pair, with larger doses being more likely to be associated with an abnormal QT. The median maximum QRS width was 85 ms (IQR 80-90 ms; range 70-145 ms) and the QRS was greater than 120 ms in only 24 admissions (7%, 95% CI 4-10). CONCLUSIONS: Venlafaxine overdose causes only minor abnormalities in the QT and QRS intervals, unlikely to be associated with major arrhythmias, except possibly with large doses.

Tricyclic antidepressant toxicity treated with massive sodium bicarbonate.

Tricyclic antidepressant (TCA) morbitity is primarily due to cardiac arrhythmias and hypotension, which become more refractory to treatment as acidosis progresses (Ann Emerg Med. 1985;14:1-9; Clin Toxicol. 2007;45:203-233; Flomenbaum N, Goldfrank L, Hoffman R, et al. Goldfrank's toxicologic emergencies. 8th ed. McGraw-Hill Companies, Inc, 2006). Early recognition and aggressive treatment are necessary for patient survival.

[Misuse of substances theoretically without abuse potential--case series]. / Naduzywanie substancji teoretycznie bez znanego potencjalu uzalezniajacego--przeglad przypadków.

The aim of our study was to present cases of misuse of different substances theoretically without abuse potential. In the last few years such behavior became an increasing problem in toxicological and emergency units. Lack of typical signs of intoxication with psychoactive substances, and negative results of standard toxicological tests may be a challenge for toxicologists and emergency medicine practitioners.

Predictive factors for generalized seizures after deliberate citalopram overdose.

AIMS: Seizures are a recognized complication of citalopram overdose. The present study sought to establish risk factors for seizures in this high-risk patient group, including stated dose ingested, co-ingested drugs or ethanol, and electrolyte disturbances. METHODS: A retrospective casenote review was carried out of patients who attended the Emergency Department due to citalopram overdose between January 2000 and July 2007 inclusive. Stepwise logistic regression analysis considered age, gender, stated citalopram dose, acute ethanol consumption, co-ingested drugs, administration of activated charcoal, and hyponatraemia. RESULTS: There were 241 patients (177 women), and the median (interquartile range) stated citalopram dose was 300 mg (200 to 600 mg). Generalized seizures occurred in 18 patients (7.5%). Logistic regression analysis found co-ingested tricyclic antidepressants or venlafaxine predicted seizures with odds ratio = 15 (95% confidence interval 3, 75). In the absence of co-ingested drugs, the minimum citalopram dose associated with seizures was 400 mg. Odds ratio for seizures = 1.1 (95% confidence interval 1.0, 1.2) for every 100 mg increment in citalopram dose. Seizures were associated with a greater need for invasive ventilatory support, higher creatine kinase activity, and prolonged hospital stay. CONCLUSIONS: Generalized seizures are an important manifestation of citalopram toxicity, and cannot be explained solely by electrolyte disturbances or co-ingestion of other drugs or ethanol. The strongest predictors of seizures in this patient series were ingestion of high citalopram dosages and co-ingestion of drugs capable of lowering seizure threshold.

Venlafaxine ingestion is associated with rhabdomyolysis in adults: a case series.

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.

Serotonin syndrome:case report and current concepts.

Selective serotonin reuptake inhibitors (SSRI's) are increasingly being used as the first line therapeutic agent for the depression. It is therefore not unusual to see a case of overdose with these agents. More commonly an adverse drug reaction may be seen among the older patients who are particularly vulnerable to the serotonin syndrome due to multiple co-morbidity and polypharmacy. The clinical picture of serotonin syndrome (SS) is non-specific and there is no confirmatory test. SS may go unrecognized because it is often mistaken for a viral illness, anxiety, neurological disorder or worsening psychiatric condition.

Successful use of cardiac allograft from serotonin antagonist intoxication.

BACKGROUND: Compromised organ donors are generally not accepted for heart transplantation (HT) despite the increasing number of critically ill patients on the waiting lists. By extending the donor criteria to include certain cases of intoxication, the organ shortage may be reduced. METHODS: The case of a successful orthotopic HT with an allograft from a donor poisoned by antidepressant overdose is presented. RESULTS: Early graft function was satisfactory with anteroseptal dyskinesis and an ejection fraction of 75% on echocardiography. The cardiac allograft recipient suffered some postoperative complications including gastrointestinal problems. The following period was up to now uneventful. Discharge from the intensive care unit was after 4 days. In-hospital stay was prolonged at 26 days. CONCLUSIONS: Because of limited myocardial toxicity, donor hearts from certain victims of antidepressant intoxication may be safely used for HT. Existing cardiac organ donor criteria must be reevaluated to maximise the available organ pool.

Relative toxicity of venlafaxine and selective serotonin reuptake inhibitors in overdose compared to tricyclic antidepressants.

BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) and venlafaxine have been regarded as less toxic in overdose than tricyclic antidepressants (TCAs). Within the TCAs, dothiepin has greater toxicity. Venlafaxine may be more toxic than SSRIs. AIM: To assess the toxicity in overdose of venlafaxine and SSRIs compared to TCAs, and of dothiepin compared to other TCAs. DESIGN: Cohort study of prospectively collected data from the Hunter area, NSW, Australia. METHODS: First admissions with antidepressant deliberate self-poisoning (DSP) (November 1994 to April 2000) were identified; the presence of seizures, life-threatening arrhythmias, coma, serotonin toxicity or ICU admission, and QRS duration were noted. RESULTS: There were 538 admissions, with no deaths. The odds ratio (OR) for seizures with dothiepin vs. other TCAs was 3.4 (95%CI 1.2-9.9). Seizures occurred in 7/51 (14%) venlafaxine overdoses; all patients with seizures consumed > or =900 mg. The OR for seizures vs. TCAs was 4.4 (95%CI 1.4-13.8). Coma was less likely with venlafaxine and SSRIs. SSRIs, but not venlafaxine, were less likely to prolong the QRS to > or =100 ms. ICU admission was less likely for SSRIs. Serotonin toxicity was much more common with venlafaxine and SSRIs. DISCUSSION: Venlafaxine and dothiepin are pro-convulsant in overdose. Venlafaxine is more likely to cause serotonin toxicity, but less likely to cause coma than TCAs. SSRIs are less likely to cause coma, require ICU admission, or prolong the QRS, but are more likely to cause serotonin toxicity. Antidepressants other than TCAs or venlafaxine should be considered in patients at risk of seizure or suicide.