VENLAFAXINE INGESTION IS ASSOCIATED WITH RHABDOMYOLYSIS IN ADULTS: A CASE SERIES

Brain Targeting of Venlafaxine via Intranasal Transbilosomes Thermogel for Improved Management of Depressive Disorder

The current research aimed to design and optimize hyaluronic acid-coated transbilosomes containing venlafaxine (VLF-HA-TBLs) for nose-to-brain delivery for improved management of depressive disorder. Venlafaxine-loaded transbilosomes (VLF-TBLs) were developed according to the film hydration procedure, optimized for maximum efficiency using the quality by design-based Box-Behnken design (BBD), and then coated with hyaluronic acid (HA). The optimized VLF-HA-TBLs were subjected to in vitro characterization, integrated into a thermolabile gel, and then exposed to in vivo evaluation studies. The results revealed that the VLF-HA-TBLs formulation exhibited acceptable size (185.6 ± 4.9 nm), surface charge (-39.8 ± 1.7 mV), and entrapment efficiency (69.6 ± 2.6 %). The morphological study revealed that nanovesicles were spherical and displayed a consistent size distribution without particle aggregation. It also showed improved ex vivo nasal diffusion and a prolonged release profile. In addition, the formulated VLF-HA-TBLs were stable under the studied conditions and tolerable when applied intranasally. Compared to the intranasal administration of VLF solution (VLF-SOL), the biodistribution analysis showed that VLF-HA-TBLs delivered intranasally had a relative bioavailability of 441 % in the brain and 288 % in plasma. Moreover, the intranasal delivery of VLF-HA-TBLs demonstrated much higher bioavailability (512 %) in the brain compared to VLF-SOL administered intravenously. Collectively, it could be possible to infer that HA-TBLs might be an effective nanocarrier to administer VLF to the brain via the nasal route.

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.

Venlafaxine-Associated Rhabdomyolysis: A Literature Review

PURPOSE

This systematic review aimed to investigate the clinical manifestations and characteristics of venlafaxine-associated rhabdomyolysis.

METHODS

A systematic search was conducted in PubMed, Elsevier, Science Direct, Embase, Springer Link, Wiley Online Library, CNKI, and Wanfang databases from the date of database inception to January 2023. Previously reported cases of venlafaxine-associated rhabdomyolysis were identified, and relevant data from these cases were collected for descriptive statistical analysis. Cases that met the inclusion criteria were evaluated to determine the correlation between adverse reactions and venlafaxine.

RESULTS

A total of 12 patients with venlafaxine-associated rhabdomyolysis were included. None of these patients had a history of muscle pain or discomfort. Of the 12 patients, 5 patients received venlafaxine at doses of ≤225 mg/d, whereas the remaining 7 patients received doses exceeding 225 mg/d. The main clinical symptoms included myalgia, muscle weakness, and renal injury. All 12 patients discontinued venlafaxine and received symptomatic care.

CONCLUSIONS

Venlafaxine, used either as a monotherapy or in combination with other drugs, may be associated with rhabdomyolysis. Creatine kinase levels may normalize or significantly decrease after discontinuation of venlafaxine and symptomatic treatment.

Pressure Necrosis Requiring Fasciotomy After Kratom Overdose

INTRODUCTION

Kratom (Mitragyna speciosa) is a popular plant-based extract that has dose-dependent stimulatory and sedative effects. It has been used for self-treatment of opioid withdrawal and can result in seizures, hepatotoxicity, and infectious complications from bacterial contamination. Reports of morbidity and mortality associated with Kratom may be confounded by coingestants. We report a case of severe rhabdomyolysis and pressure necrosis leading to fasciotomy in a patient who was using Kratom.

CASE REPORT

A 31-year-old male with substance use presented to the emergency department after loss of consciousness for 6 hours after smoking Kratom. He was found to have rhabdomyolysis, acute renal and hepatic injury, and electrolyte disturbances. No ethanol was detected, and urine drug screen was negative. Over the next 3 hours, the patient developed signs of compartment syndrome and he was transferred to the operating room for fasciotomy. He required continuous renal replacement therapy for 48 hours and his labs and clinical status improved. He was discharged 18 days later. A serum and urine sample from the first day of presentation were analyzed for mitragynine and 7-hydroxymitragynine using an Ultra Performance Liquid Chromatography-Tandem Mass Spectrometer (UPLC-MSMS) method. The serum mitragynine was 5 ng/mL and the urine mitragynine 6 ng/mL.

CONCLUSIONS

Although there are numerous reports of opioids resulting in prolonged periods of immobilization and rhabdomyolysis, this is not commonly reported in Kratom overdoses.This case report highlights the profound sedative effect of Kratom and the potential of pressure necrosis injury resulting in rhabdomyolysis and compartment syndrome requiring fasciotomy.

Characterization of intentional-abuse venlafaxine exposures reported to poison control centers in the United States

Background: Venlafaxine use to achieve an amphetamine-like high has been described but data regarding the epidemiology and clinical effects are sparse. Objectives: Describe the prevalence and toxicity of venlafaxine abuse reported to US poison control centers. Methods: This was a retrospective review of venlafaxine exposures reported to the National Poison Data System (NPDS) from 2000 to 2016. Inclusion criteria were: age 12 years and older, reason for exposure intentional-abuse, and either single-substance exposure or venlafaxine was the first substance. The primary outcome was prevalence of intentional-abuse of venlafaxine. Secondary outcomes characterized demographics, geographic distribution, toxicity, and outcomes. Results: Intentional-abuse accounted for 752 of 85,621 venlafaxine exposures. Overall prevalence was 87.8 intentional-abuse exposures/10,000 venlafaxine exposures reported to NPDS (range, 59.3-117.6/10,000). Prevalence decreased from 107/10,000 in 2000 to 59.3/10,000 in 2016. Median age was 23 years and 50% were female. Primary route was ingestion (90.8%) with 4.7% using venlafaxine via inhalation/intranasal insufflation, and 3.7% both routes. There were 227 venlafaxine-only exposures; 54.0% were treated/released from the emergency department, 20% were admitted for medical management, 9.0% to a psychiatric facility, and 17.0% managed at home. Known medical outcomes for single-substance exposures were: no effect (24.0%), minor (39.0%), moderate (33.0%), and major (4.0%); no deaths occurred. Most frequent clinical effects were tachycardia (33.9%), drowsiness (20.7%), and agitation (11.5%). Conclusion: The prevalence of venlafaxine abuse reported to poison control centers has decreased. Medical outcomes are usually not serious. Clinicians should be aware that non-medical use is possible but infrequently reported to poison control centers.

Bilateral sciatic neuropathy with severe rhabdomyolysis following venlafaxine overdose: A case report

RATIONALE

Venlafaxine is an antidepressant and anxiolytic agent that functions by inhibiting central serotonin and norepinephrine reuptake, and it is a relatively recently introduced drug. In particular, overdose of venlafaxine has been reported to cause severe cardiac toxicity including ventricular tachycardia, prolongation of QT interval, and seizure or severe muscular injury. However, reports describing venlafaxine-induced rhabdomyolysis with neuropathy remain scarce. Accordingly, we report such a case involving a 49-year-old woman with bilateral sciatic neuropathy combined with rhabdomyolysis following venlafaxine overdose.

PATIENT CONCERNS

The patient complained of severe pain and tenderness in both thighs, weakness in both ankle flexor and extensor muscles, and a tingling sensation in the toes of both feet.

DIAGNOSES

Bilateral sciatic neuropathy combined with rhabdomyolysis following venlafaxine overdose.

INTERVENTION

Needle electromyography revealed fibrillation potentials and positive sharp waves, with absent recruitment in all the major muscles innervating the sciatic nerve bilaterally. Pelvic magnetic resonance imaging was performed after electromyography and revealed multifocal enhancement of signal intensity, suggesting muscle necrosis in the gluteus and thigh muscles, and swelling of both sciatic nerves on short tau inversion recovery (STIR) imaging sequences.

OUTCOMES

Two months later, the patient's ankle dorsiflexion strength, measured with manual muscle test, was grade 0/0, and ankle plantar flexion was grade 0/0. The patient reported little sensation at the lateral and posterior aspects of her lower leg, and dorsum and sole of the foot. A follow-up electromyography study revealed improvement in the long head of the right biceps femoris; polyphasic motor unit action potentials with diminished recruitment were observed, but otherwise unchanged.

LESSONS

When encountering patients who have overdosed on venlafaxine, it is very important to detect and treat severe complications such as cardiac toxicity, seizure, and rhabdomyolysis, among others. However, if rhabdomyolysis has already materialized, it should not be forgotten that the secondary damage caused by it. Physicians should rapidly detect and be minimized to mitigate future complications.

Adverse reactions to dietary supplements containing red yeast rice: assessment of cases from the Italian surveillance system

AIMS

Red yeast rice (RYR) is contained in dietary supplements for patients with dyslipidemia. RYR supplements contain monacolin K, which is chemically identical to lovastatin, a licensed drug with a well-known risk profile. We aim to describe the safety profile of RYR by analysing spontaneous reports of suspected adverse reactions (ARs).

METHODS

Within the Italian Surveillance System of Natural Health Products, suspected ARs were collected and evaluated by a multidisciplinary group of experts to assess causality using the WHO-UMC system or the CIOMS/RUCAM score, for hepatic reactions. The public version of the WHO-Vigibase was also queried.

RESULTS

From April 2002 to September 2015, out of 1261 total reports, 52 reports concerning 55 ARs to RYR dietary supplements were collected. ARs consisted in myalgia and/or increase in creatine phosphokinase (19), rhabdomyolysis (1), liver injury (10), gastrointestinal reactions (12), cutaneous reactions (9) and other reactions (4). Women were involved in 70% of cases. In 13 cases, the reaction required hospitalization, and 28 patients were taking other medications. Dechallenge was positive in 40 reactions (73%), rechallenge was positive in 7. Causality resulted as certain (1), probable (31, 56%), possible (18, 34%), unlikely (3) or unassessable (2). Similar distribution emerged from the WHO-Vigibase.

CONCLUSIONS

The potential safety signals of myopathies and liver injury raise the hypothesis that the safety profile of RYR is similar to that of statins. Continuous monitoring of dietary supplements should be promoted to finally characterize their risk profile, thus supporting regulatory bodies for appropriate actions.

Rare case of severe serotonin syndrome leading to bilateral compartment syndrome

The term 'serotonin syndrome' describes a constellation of symptoms caused by serotonergic overstimulation. Its characteristic clinical presentation consists of encephalopathy, neuromuscular signs and autonomic hyperactivity. After removal of the offending agent, the clinical course is usually self-limited but can occasionally lead to severe symptoms. We report the case of a 68-year-old woman who presented emergently with encephalopathy. Home medications included paroxetine and dextroamphetamine/amphetamine. Physical examination revealed tachycardia, tachypnoea, diaphoresis, rigidity, hyperreflexia and clonus. Given the fast onset of symptoms, a diagnosis of serotonin syndrome was made. Laboratory studies showed acute-on-chronic kidney injury and elevated creatine kinase. The patient's mental status quickly returned to baseline with supportive care. Her rhabdomyolysis, however, persisted and led to acute compartment syndrome in her lower extremities. After bilateral leg fasciotomies and treatment of a severe wound infection with intravenous antibiotics, the patient has now recovered with complete resolution of her symptoms.

Development and evaluation of brain targeted intranasal alginate nanoparticles for treatment of depression

The purpose of the present study was to investigate the potential of Venlafaxine loaded alginate nanoparticles (VLF AG-NPs) for treatment of depression via intranasal (i.n.) nose to brain delivery route. The VLF AG-NPs were prepared and optimized on the basis of various physio-chemical characteristics. Pharmacodynamic studies of the VLF AG-NPs for antidepressant activity were carried in-vivo by forced swimming test and locomotor activity test on albino Wistar rats. VLF AG-NPsi.n. treatment significantly improved the behavioural analysis parameters i.e. swimming, climbing, and immobility in comparison to the VLF solutioni.n. and VLF tabletoral. The intranasal VLF AG-NPs also improved locomotor activity when compared with VLF solutioni.n. and VLF tabletoral. Confocal laser scanning fluorescence microscopy studies were performed on isolated organs of rats after intravenous and intranasal administrations of Rodamine-123 loaded alginate nanoparticles to determine its efficacy for nose to brain delivery and also for its qualitative distribution to other organs. Brain uptake and pharmacokinetic studies were performed by determination of VLF concentration in blood and brain respectively for VLF AG-NPsi.n., VLF solutioni.n. and VLF solutioni.v. The greater brain/blood ratios for VLF AG-NPsi.n. in comparison to VLF solutioni.n. and VLF solutioni.v. respectively at 30 min are indicative of superiority of alginate nanoparticles for direct nose to brain transport of VLF. Thus, VLF AG-NPsi.n. delivered greater VLF to the brain in comparison to VLF solution which indicates that VLF AG-NPs could be a promising approach for the treatment of depression.

Insights into direct nose to brain delivery: current status and future perspective

Now a day's intranasal (i.n) drug delivery is emerging as a reliable method to bypass the blood-brain barrier (BBB) and deliver a wide range of therapeutic agents including both small and large molecules, growth factors, viral vectors and even stem cells to the brain and has shown therapeutic effects in both animals and humans. This route involves the olfactory or trigeminal nerve systems which initiate in the brain and terminate in the nasal cavity at the olfactory neuroepithelium or respiratory epithelium. They are the only externally exposed portions of the central nervous system (CNS) and therefore represent the most direct method of noninvasive entry into the brain. This approach has been primarily used to explore therapeutic avenues for neurological diseases. The potential for treatment possibilities with olfactory transfer of drugs will increase as more effective formulations and delivery devices are developed. Recently, the apomorphine hydrochloride dry powders have been developed for i.n. delivery (Apomorphine nasal, Lyonase technology, Britannia Pharmaceuticals, Surrey, UK). The results of clinical trial Phase III suggested that the prepared formulation had clinical effect equivalent to subcutaneously administered apomorphine. In coming years, intranasal delivery of drugs will demand more complex and automated delivery devices to ensure accurate and repeatable dosing. Thus, new efforts are needed to make this noninvasive route of delivery more efficient and popular, and it is also predicted that in future a range of intranasal products will be used in diagnosis as well as treatment of CNS diseases. This review will embark the existing evidence of nose-to-brain transport. It also provides insights into the most relevant pre-clinical studies of direct nose-brain delivery and delivery devices which will provide relative success of intranasal delivery system. We have, herein, outlined the relevant aspects of CNS drugs given intranasally to direct the brain in treating CNS disorders like Alzheimer's disease, depression, migraine, schizophrenia, etc.

Low-dose venlafaxine-induced severe rhabdomyolysis: a case report

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.

Venlafaxine loaded chitosan NPs for brain targeting: pharmacokinetic and pharmacodynamic evaluation

The purpose of the present investigation was to prepare venlafaxine (VLF) loaded chitosan nanoparticles (NPs) to enhance the uptake of VLF to brain via intranasal (i.n.) delivery. VLF loaded chitosan NPs were prepared and characterized for particle size, size distribution, zeta potential, encapsulation efficiency and in vitro drug release. In order to investigate the localization of chitosan NPs in brain and other organs qualitatively confocal laser scanning microscopy technique was carried out using rhodamine-123 (ROD-123) as marker. The levels of VLF in plasma and brain tissues were also determined, the brain/blood ratios of VLF for VLF (i.v.), VLF (i.n.), VLF chitosan NPs (i.n.) were 0.0293, 0.0700 and 0.1612, respectively, at 0.5h, indicative of better brain uptake of VLF chitosan NPs. The higher drug transport efficiency (508.59) and direct transport percentage (80.34) of VLF chitosan NPs as compared to other formulations suggest its better efficacy in treatment of depression.

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.

Venlafaxine-associated serotonin syndrome causing severe rhabdomyolysis and acute renal failure in a patient with idiopathic Parkinson disease

A 43-year-old male patient with idiopathic Parkinson disease, on dopaminergic therapy, was admitted with confusion and agitation, diaphoresis, and hyperkinesia after the commencement of the serotonin-noradrenaline reuptake inhibitor venlafaxine 2 weeks prior for depression. He was found to have severe rhabdomyolysis and developed acute renal failure. The most likely diagnosis was serotonin syndrome induced by venlafaxine, although neuroleptic malignant syndrome was also considered. The differential diagnosis, atypical features in this presentation, and possible mechanisms are discussed.

Assessment of serum creatine kinase among adolescent patients following jimsonweed (Datura stramonium) and moonflower (Datura inoxia) ingestions: a review of 11 cases

INTRODUCTION

Datura stramonium (DS) (jimsonweed) is well known for its abuse potential for hallucinogenic effects and Datura inoxia (DI) (moonflower) has been abused for similar effects. To our knowledge, only one case report describes rhabdomyolysis in association with DS or DI ingestion.

CASE IDENTIFICATION AND DETAILS

Patient hospital charts were retrospectively screened from January 1, 2002 to December 31, 2007 to identify patients with qualifying ICD-9 codes for toxic plant ingestions. We report on 11 patient cases of DS/DI ingestions in which serum creatine kinase (CK) concentrations were monitored. These admissions occurred at our hospital over a 6-year period. Serum CK concentrations ranged from 72 to 70,230 U/L. Only three patients had serum CK concentrations greater than 1,000 U/L. One patient with a peak concentration of 70,230 U/L and a positive myoglobinuria was diagnosed with rhabdomyolysis.

DISCUSSION

Based on our review of the literature and these cases, it is possible that serum CK concentrations may be elevated more frequently than previously realized. The clinical significance of this abnormal laboratory value is uncertain with the majority of patients remaining asymptomatic without any clinical evidence of rhabdomyolysis.

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.

Sertraline-Induced Rhabdomyolysis in an Elderly Patient with Dementia and Comorbidities

Objective:

To describe a case of sertraline-induced rhabdomyolysis in an elderly patient with dementia and comorbidities.

Case Summary:

A 71-year-old woman visited a psychiatrist in September 2007 for her depressed mood. Her medical history included vascular dementia accompanied by depression, arterial hypertension, and heart failure, as well as cardiac pacemaker implantation several years earlier for severe bradyarrythmia. She had begun taking amisulpride 50 mg/day and diazepam 2 mg at bedtime 6 months prior to the psychiatrist appointment, with poor relief of her depressed mood. Her drug therapy also included nicergoline 30 mg/day, amlodipine 5 mg/day, aspirin 100 mg/day, candesartan 16 mg/day, and atenolol 25 mg/day. At this psychiatrist visit, sertraline 50 mg/day was added for her depression, and was continued after a geriatrician visit in October. Her mood improved significantly. On December 18, 2007, she was admitted to the cardiology unit to undergo a pacemaker replacement. Laboratory tests revealed creatine kinase (CK) 7952 IU/L, lactate dehydrogenase 1021 IU/L, myoglobin 2322 U/L, and aspartate aminotransferase 362 IU/L, resulting in a diagnosis of iatrogenic rhabdomyolysis. Amisulpride and sertraline were discontinued. On December 24, serum CK was 839 IU/L and myoglobin was 91 U/L and the patient was discharged. On January 22, laboratory tests showed normal values of CK, CK-MB, and myoglobin. Sertraline 50 mg/day was again prescribed for the patient's persistent depressed mood. Fifteen days later, blood tests showed CK 1327 IU/L and myoglobin 324 U/L; therefore, the drug was discontinued. CK and myoglobin levels normalized a week later. On April 2, escitalopram was started. At time of writing, there was no evidence of any increase in CK, myoglobin, or other markers of rhabdomyolysis.

Discussion:

The Naranjo probability scale indicated a probable relationship between sertraline treatment and the onset of rhabdomyolysis. No relationship between amisulpride and rhabdomyolysis was found. Furthermore, rechallenge with sertraline caused CK and myoglobin to again increase, which was reversed following a discontinuation of sertraline. The patient's other comorbidities and medications have not been suggested as possible interactions with sertraline that can cause rhabdomyolysis. Genetic defects of sertraline demethylation and/or P-glycoprotein binding or concurrent circumstances may explain the onset of rhabdomyolysis in this particular patient.

Conclusions:

This patient's rhabdomyolysis was probably induced by sertraline therapy.

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.

Doxylamine toxicity: seizure, rhabdomyolysis and false positive urine drug screen for methadone

The present report highlights the possible adverse effects of doxylamine, a common over the counter sleep aid. Doxylamine is an antihistamine that at toxic doses can cause anticholinergic effects, including seizures, rhabdomyolysis and death. The following case describes a patient with doxylamine toxicity who presented with seizure and confusion. Our patient was managed symptomatically, and remained otherwise stable throughout his hospitalisation. This case is atypical in terms of a delayed rhabdomyolysis and a false positive urine drug screen test for methadone. There is evidence that doxylamine at toxic levels can lead to false positives for methadone and phencyclidine testing using immunoassay-based urine drug screen kits. Urine drug screen testing on patients who are hospitalised is typically performed using immunoassays. However, in certain cases confirmatory secondary testing may be required. Doxylamine is prone to abuse and knowledge of the clinical presentation of its toxicity and the management of acute overdose can be life-saving.

Patterns of antiepileptic drug overdose differ between men and women: admissions to the Edinburgh Poisons Unit, 2000-2007

BACKGROUND AND AIMS

Antiepileptic drugs are increasingly used in patients with psychiatric disorders who are at increased risk of self-harm. This might increase the likelihood that these agents are used as a means of overdose. This study was designed to examine the rate of occurrence of antiepileptic drug overdose between 2000 and 2007.

METHODS

A retrospective observational study examined patterns of antiepileptic drug overdose in patients admitted to the Edinburgh Poisons Unit, and compared prescription data for the corresponding region. Data were compared using chi-square trend tests.

RESULTS

There were 18 010 admissions to the Toxicology Unit, and 613 patients ingested at least one antiepileptic drug (3.4%). The most frequently implicated were carbamazepine, sodium valproate, phenytoin and lamotrigine, which corresponded with those most commonly prescribed. Women were more likely to ingest lamotrigine than men (P < 0.0001), and less likely to ingest sodium valproate (P = 0.0234). Patients that ingested antiepileptic drugs were more likely to be admitted to hospital for >1 day (22% vs. 8%, P < 0.0001) and need transfer to a psychiatric facility (14% vs. 7%, P < 0.0001).

CONCLUSIONS

Patients that ingested antiepileptic drugs required more intensive medical and psychiatric intervention compared to ingestion of other agents. Significant gender differences were noted in the specific antiepileptic drug ingested. Further work is required to establish whether this discrepancy may be explained by gender-based prescribing practices.

Screening of venlafaxine hydrochloride for transdermal delivery: passive diffusion and iontophoresis

The objective of the study was to investigate in vitro transdermal delivery of venlafaxine hydrochloride across the pigskin by passive diffusion and iontophoresis. For passive diffusion, experiments were carried out in Franz diffusion cell whereas for iontophoretic permeation, the diffusion cell was modified to contain both the donor and return electrode on the same side of skin. Anodal iontophoresis was carried out using a current density of 0.5 mA/cm(2). Donor concentrations used were 585.5 mg/ml (saturated solution) and 100 mg/ml. Experiments initially performed to determine the transport efficiency of venlafaxine ions showed promising results. Iontophoresis increased the permeation rate at both concentration levels over their passive counterparts (P < 0.01), but surprisingly higher steady-state flux was obtained from lower donor drug load (P < 0.01). The favorable pH of the unsaturated solutions is suggested to be the cause for this effect. Mild synergistic effect was observed when iontophoresis was carried out incorporating peppermint oil in the donor but the same was not found in passive diffusion. Highest steady-state flux obtained in the experiment was 3.279 mumol/cm(2)/h when peppermint oil (0.1%) was included in the donor. As the maintenance requirement of venlafaxine hydrochloride is approximately 9.956 mumol/h, the results suggested that the drug is a promising candidate for iontophoretic delivery.

A case from the department of neurology

Uncompleted suicide attempts are a significant cause of morbidity, which in catastrophic cases can be both medically and ethically challenging to manage. We discuss the case of a 63-year-old man who survived a suicide attempt by venlafaxine (Effexor) overdose, causing an intracranial hemorrhage and leaving him in an apparently awake but noncommunicative state. Ethical concerns arose when considering if he should be indefinitely maintained on life support. These include the difficulties of characterizing his level of consciousness and prognosis; establishing his decisional capacity regarding end-of-life decisions in a setting of depression and suicidality; and assessing the suitability of a surrogate decision-maker. In conclusion, we discuss whether the fact that his grave neurological condition was caused by a suicide attempt was relevant to the decision to continue or withdraw life support.