Delayed onset of liver injury after intentional chloroform overdose: a case report and literature review

Chloroform is a recognised cause of acute liver injury, although now rarely encountered in clinical practice. We present a case of inhalational chloroform self-poisoning in a 47-year-old man that presented to hospital initially with reduced conscious level and later developed acute liver injury that was treated with intravenous acetylcysteine. This paper reviews the existing literature and presents a summary of the mechanisms of chloroform hepatotoxicity. Published cases show that there is a characteristic delay of 24 to 48 hours between chloroform exposure and elevation of liver transaminase activity. Therefore, clinicians need to provide an appropriate duration of monitoring in order to detect the occurrence of this important toxic effect.

Global research production in glyphosate intoxication from 1978 to 2015: A bibliometric analysis

BACKGROUND

Glyphosate (N-phosphonomethylglycine) has been used as a broad-spectrum herbicide that has been widely used in the agricultural industry and also available for home use. The main aim of this study is to present a general overview of glyphosate intoxication-related publications from its introducing since the early 1970s using bibliometric technique.

METHODS

On June 23, 2016, a literature search of the Scopus database was performed. We then extracted and analyzed the data using well-established qualitative and quantitative bibliometric indices: Publication year, affiliation, document type, country name, subject category, journal name, publishing language, and collaboration and citation patterns.

RESULTS

We recognized a total of 3735 publications on glyphosate published between 1973 and 2015. There were 875 publications related to glyphosate intoxication in the Scopus database published between 1978 and 2015. Articles (757) comprised 86.5% of the total publications, followed by reviews (41; 4.7%). Most publications were published in English (87.9%), followed by Portuguese (6.6%). The number of publications related to glyphosate intoxication increased from 44 in 1978-1987 up to 152 in 1996-2005 and then quadrupled in 2006-2015. The United States was the leading country with 180 documents representing 20.6%, followed by Brazil (120; 13.7%), Canada (78; 8.9%), Argentina (61; 7.0%), and France (57; 6.5%). The 85.6% of the publications was cited, and the average of citation per document was 17.13 with h-index of 55. Furthermore, the United States achieved the highest h-index of 33. Most of the global international collaborations are made with researchers from the United States, who collaborated with 23 countries/territories in 44 publications.

CONCLUSIONS

The trends in global glyphosate-related research between 1978 and 2015 were evaluated by a bibliometric technique. Results showed that English was the leading publishing language, and the major publication type was original article. Findings showed that number of research publications related to glyphosate intoxication increased significantly in the last decade. The United States and Brazil are the two most productive countries in research on glyphosate intoxication. This study will be beneficial to policy makers by identifying areas that need greater investment and research funding to target appropriate agriculture sectors so as to improve glyphosate safety in a global setting.

Olanzapine overdose is associated with acute muscle toxicity

Olanzapine is an atypical antipsychotic that is reported to cause myopathy and raised creatine kinase (CK) levels. The prevalence and severity of acute myopathy after deliberate olanzapine ingestion are unclear. Therefore, we reviewed casenotes from 64 consecutive patients admitted to our institution after olanzapine overdose. Overall, serum CK was higher than five times the upper limit of normal in 17% of patients. The prevalence of raised CK values was positively correlated with the stated quantity of olanzapine ingested, suggesting a dose-dependent relationship for acute muscle toxicity. There was an apparent delay of 12 hours or more between olanzapine ingestion and the occurrence of maximum CK. Despite the high prevalence of acute muscle toxicity after olanzapine ingestion, none of the patients developed renal failure.

Emergency Presentation of an Elderly Female Patient with Profound Hypoglycaemia

We present the case of an elderly non-diabetic female who was admitted to hospital as an emergency due to loss of consciousness. Her clinical presentation was consistent with hypoglycaemia due to a massive insulin overdose. However, the patient refuted the possibility of insulin administration, and the circumstances were reported to the police for investigation. This case demonstrates the clinical and biochemical characteristics of insulin overdose. Furthermore, it serves to illustrate the sequence of events that may be created when foul play is suspected, and the factors related to patient confidentiality that require consideration by the responsible physician.

Scientific research related to calcium channel blockers poisoning: Bibliometric analysis in Scopus, 1968-2012

PURPOSE

Calcium channel blockers (CCBs) were the most common agents associated with a significant morbidity and mortality rate. The main objective of this study was to examine the publication pattern related to CCBs poisoning at the global level using bibliometric analysis of articles published in SciVerse Scopus online database.

METHODS

Data were searched for documents that contained specific words regarding CCB poisoning as keywords in the title. No time period limitations were specified in the search regarding the starting year. The ending date of the search was 31 December 2012.

RESULTS

The criteria were met by 713 publications from 53 countries. The largest number of articles associated with CCBs was from the United States (30%), followed by the United Kingdom (7.4%), Japan (6%), and Germany (5.6%). No data related to CCBs were published from 159 (75%) of 212 countries registered in World Bank online database. There was no correlation between the number of published articles in the country and its population size (r = 0.03, p > 0.926). United Kingdom and Australia were the leading countries in terms of number of CCBs publications per million inhabitants (0.83 and 0.82 articles per million inhabitants, respectively), followed by the United States (0.68). Countries with a large population, such as India, tended to rank relatively low (0.01 articles per million inhabitants). The total number of citations at the time of data analysis (23 October 2014) was 6462, with an average of 9.1 citations per document. The highest median (interquartile range) number of citations was 8 (8-18) for the United States, followed by 6 (1-21) for Australia, 5 (1-15) for the United Kingdom, and 5 (1-24) for Canada. The h-index of the retrieved documents was 37.

CONCLUSIONS

Scientific production on CCBs poisoning is increasing; nonetheless, the international collaboration is still rare. The amount of CCBs-based research activity was low or not available in most countries. More regional epidemiological studies are required to bridge the gap in CCBs-based research and to promote better evaluation of CCBs poisoning worldwide.

Global research productivity of N-acetylcysteine use in paracetamol overdose: A bibliometric analysis (1976-2012)

PURPOSE

The main objective of this study was to examine the publication pattern of N-acetylcysteine (NAC) research output for paracetamol overdose at the global level.

METHODS

Data were searched for documents that contained specific words regarding NAC and paracetamol as keywords in the title and/or abstract and/or keywords. Scientific output was evaluated based on a methodology developed and used in other bibliometric studies. Research productivity was adjusted to the national population and nominal gross domestic product per capita.

RESULTS

The criteria were met by 367 publications from 33 countries. The highest number of articles associated with the use of NAC in paracetamol overdose was from the United States of America (USA; 39.78%), followed by the United Kingdom (UK; 11.99%). After adjusting for economy and population power, USA (2.822), Iran (1.784) and UK (1.125) had the highest research productivity. The total number of citations at the time of data analysis (14 March 2014) was 8785 with an average of 23.9 citations per document and a median (interquartile range) of 6 (1-22). The h-index of the retrieved documents was 48. The highest h-index was 32 for USA, followed by 20 for UK. Furthermore, the highest number of collaborations with international authors for each country was held by USA with 11 countries, followed by Canada with 7 countries.

CONCLUSION

The amount of NAC-based research activity was low in some countries, and more effort is needed to bridge this gap and to promote better evaluation of NAC use worldwide. Our findings demonstrate that NAC use for paracetamol overdose remains a hot issue in scientific research and may have a larger audience compared with other toxicological aspects. Editors and authors in the field of toxicology might usefully promote the submission of work on NAC in future to improve their journal's impact.

Impact of amending the acetylcysteine marketing authorisation on treatment of paracetamol overdose

In September 2012, the Medicines and Healthcare products Regulatory Agency (MHRA) substantially amended the Marketing Authorisation for acetylcysteine following an extensive review. The present study examined the impact of this license change on patterns of acetylcysteine use in patients presenting to hospital after paracetamol (acetaminophen) overdose. Between September 2011 and April 2013, 785 consecutive patients presented to York Hospital due to paracetamol overdose, and a before-after analysis was used to compare outcomes. There were 483 patients before and 302 patients after the license amendment, and age, gender, acute or staggered overdose pattern, and dose were similar in both groups. In the patients with paracetamol concentrations between the "100-line" and "200-line," a significantly higher proportion received acetylcysteine treatment (51% before versus 98% after, P = 0.0029), as expected. A modest increase was also observed in relation to late or staggered overdose or cases where the time of ingestion was uncertain (53% versus 74%, P = 0.0430). The median duration of hospital stay increased across the entire study population, from 15 to 24 hours (P = 0.0159) due to the increased proportion of patients requiring acetylcysteine treatment. The findings indicate that the MHRA amendment is a financially costly intervention, and further studies are needed to examine clinical outcomes so that its cost effectiveness might be addressed.

Unplanned alcohol withdrawal: a survey of consecutive admissions to an acute medical unit in 2010 and 2011

BACKGROUND

Alcohol-related presentations to hospital have been increasing in the UK in recent years, including the occurrence of acute withdrawal. This study sought to better characterize the clinical features, patterns of treatment and outcomes in this patient group.

METHODS

Patients admitted to the Acute Medical Unit of York Hospital due to acute alcohol withdrawal are normally treated according to a protocol that involves both fixed-dose and symptom-triggered drug administration. Admissions between 2010 and 2011 inclusive were studied.

RESULTS

There were 211 admission episodes solely due to acute alcohol withdrawal, involving 127 patients (97 men, 76.4%) with median age of 45 years (interquartile range: 39-52 years). There was a high prevalence of depression (34%), alcoholic liver disease (22%) and drug misuse (12%). Total dose of chlordiazepoxide varied between 0 and 610 mg and tapered rapidly after the first day of admission. Vitamin supplements were administered to >90% of patients, including parenteral and oral in 74%, parenteral alone in 9% and oral alone in 9%. A specialist alcohol nurse reviewed patients while in hospital in 40% of cases. Approximately one-third of patients had multiple admissions for alcohol withdrawal during the study period.

CONCLUSION

A high prevalence of physical and mental health disorders was observed. The local policy permitted high initial chlordiazepoxide doses and prompt downward titration, with a broad range of doses between individuals. Approximately 10% required no specific therapy, and there may be opportunities for developing alternative pathways for delivery of care in an ambulatory setting for these patients.

Acute Caffeine Ingestion: Clinical Features in Patients Attending the Emergency Department and Scottish Poison Centre Enquiries Between 2000 and 2008

Background and Aims

Little information is available regarding the healthcare burden associated with deliberate caffeine ingestion. The present study sought to establish the impact of caffeine ingestion on hospital attendances and Poisons Centre enquiries in Scotland.

Methods

Retrospective analyses of clinical data from patients attending the Royal Infirmary of Edinburgh after acute caffeine ingestion, and TOXBASE enquiries from Scotland regarding caffeine poisoning between 2000-2008 inclusive. Cochran-Armitage trend tests were used to evaluate changes in annual admissions and TOXBASE enquiries.

Results

There were 43 hospital attendances due to deliberate caffeine ingestion, representing 0.2% of all poisoning cases. The median (interquartile range) stated dose was 1040 mg (600-1500 mg). Minor gastrointestinal symptoms were common, and no patient developed features of severe toxicity. There were 1418 enquiries to TOXBASE concerning caffeine poisoning, representing 0.2% of all poisoning enquiries from Scotland. The proportions of hospital admissions and TOXBASE enquiries due to caffeine ingestion have remained constant.

Conclusion

Caffeine ingestion is uncommon, and results in only a small number of hospital attendances and Poisons Centre enquiries. In contrast to patterns reported elsewhere, the prevalence of caffeine abuse has not increased in Scotland over recent years.

Delayed onset of acute renal failure after significant paracetamol overdose: A case series

Acute renal failure is a recognized manifestation of paracetamol toxicity, but comparatively little data is available concerning its onset and duration. The present study sought to characterize the time course of rising serum creatinine concentrations in paracetamol nephrotoxicity. Renal failure was defined by serum creatinine concentration ≥150 μmol/L (1.69 mg/dL) or ≥50% increase from baseline. Serum creatinine concentrations and alanine aminotransferase activity were considered with respect to the interval after paracetamol ingestion. There were 2068 patients with paracetamol overdose between March 2005 and October 2007, and paracetamol nephrotoxicity occurred in 8 (0.4%). All had significant hepatotoxicity, and peak serum alanine aminotransferase activity occurred at 2.5 days (2.2 to 2.9 days) after ingestion. Peak serum creatinine concentrations did not occur until 5.5 days (4.4 to 5.9 days) after ingestion (p = .031 by Wilcoxon test). Serum creatinine concentrations slowly restored to normal, and renal replacement was not required. In this patient series, rising serum creatinine concentrations only became detectable after more than 48 hours after paracetamol ingestion. Therefore, renal failure might easily be missed if patients are discharged home before this. Further work is required to establish the prevalence of paracetamol-induced nephrotoxicity, and its clinical significance.

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.

Variability in the quality of overdose advice in Summary of Product Characteristics (SPC) documents: gut decontamination recommendations for CNS drugs

AIMS

Deliberate self-poisoning is a major cause of morbidity and mortality. The Summary of Product Characteristics (SPC) document is a legal requirement for all drugs, and Section 4.9 addresses the features of toxicity and clinical advice on management of overdose. The quality and appropriateness of this advice have received comparatively little attention.

METHODS

Section 4.9 of the SPC was examined for all drugs in the central nervous system (CNS) category of the British National Formulary. Advice concerning gut decontamination was examined with respect to specific interventions: induced vomiting, oral activated charcoal, gastric lavage, and other interventions. Data were compared with standard reference sources for clinical management advice in poisoning. These were graded 'A' if no important differences existed, 'B' if differences were noted but not thought clinically important, and 'C' if differences were thought to be clinically significant.

RESULTS

SPC documents were examined for 258 medications from 67 manufacturers. The overall agreement was 'A' in 23 (8.9%), 'B' in 28 (10.9%) and 'C' in 207 (80.2%). Discrepancies were due to inappropriate recommendation of induced emesis in 21.7% (95% confidence interval 17.1, 27.1), gastric lavage in 38.4% (32.7, 44.4), other gut decontamination in 5.8% (3.6, 9.4) and failure to recommend oral activated charcoal in 57.4% (51.1, 63.4).

CONCLUSIONS

Gut decontamination advice in SPC documents with respect to CNS drugs was inadequate. Possible reasons for the observed discrepancies and ways of improving the consistency of advice are proposed.

Alerting and Surveillance Using Poisons Information Systems (ASPIS): Outcomes from an international working group

BACKGROUND

In recent years, awareness of the risks of chemical and poison exposure has increased, and a number of highly publicized terrorist events have heightened community fears. In particular, there is concern surrounding the potential risk of a covert release, which underpins the need to develop robust methods of population surveillance.

AIMS AND METHODS

This article outlines the proceedings of a working group and focuses on the need for greater international cooperation and understanding of existing toxicological surveillance systems in a variety of countries. Poison control centers have well-established local networks and experienced staff, which make them well-placed to detect chemical and poison release. This needs further development to ensure timely detection of signals, which might be better achieved by robust international networks and consistent use of data collection tools. We illustrate some of the strengths and weaknesses of existing surveillance methods, and present a position statement on the minimum dataset required by future surveillance systems.

CONCLUSIONS

Poison control centers provide a useful platform for developing surveillance activity. Having proposed a number of common aims and objectives, it is hoped that these consensus statements will inform decision makers and stimulate discussion of how international toxicological surveillance programs might best be developed.

Serum urea concentration and the risk of hepatotoxicity after paracetamol overdose

BACKGROUND

Glutathione depletion increases the incidence of toxicity after paracetamol overdose. Risk factors for toxicity, including chronic ethanol excess and malnutrition, are associated with low serum urea concentrations. Therefore, we hypothesized that low serum urea concentration might itself be predictive of hepatotoxicity in patients that present to hospital after paracetamol overdose.

METHODS

The present study prospectively collected data from 1085 patients attending the Emergency Department after paracetamol overdose. Hepatotoxicity was predefined by prothrombin time ratio >1.3 or alanine transaminase > or = 1000 U/l. Serum urea concentrations were considered in a stepwise multiple regression analysis that included paracetamol dose, co-ingestion of ethanol and other drugs, serum concentration, N-acetylcysteine, interval to treatment, vomiting and serum creatinine.

RESULTS

Median (IQR) serum urea concentrations were 3.3 mmol/l (2.7-4.2 mmol/l) in those without risk factors, compared with 3.0 mmol/l (2.4-3.9 mmol/l) in those with chronic excess ethanol intake (P < 0.001 by Mann Whitney test) and 2.5 mmol/l (1.9-2.8 mmol/l) in patients with other risk factors (P < 0.001). Multivariate analysis found that serum urea concentrations were not independently associated with hepatotoxicity.

CONCLUSION

Low serum urea concentration is not an independent risk factor for hepatotoxicity after paracetamol overdose.

Does the patient history predict hepatotoxicity after acute paracetamol overdose?

BACKGROUND

Initial management of patients who were presented to hospital after acute paracetamol overdose depends on the suspected amount ingested and more than 12 g is potentially fatal. However, the validity of this approach has received comparatively little attention.

METHODS

The present study is sought to establish whether the stated paracetamol dose might predict systemic exposure and risk of hepatotoxicity. A prospective observational study of consecutive patients presenting to the Emergency Department due to acute paracetamol overdose was performed. Serum paracetamol concentrations between 4 and 15 h post-ingestion were compared with the Rumack-Matthew '200-line' nomogram, and hepatotoxicity was defined by prothrombin time ratio >1.3 or alanine transaminase > or =1000 U/l.

RESULTS

There were 987 patients, and the stated quantity of paracetamol ingested was 0-12 g in 475 (48.1%), >12 g in 349 (35.4%) and unknown in 163 (16.5%). Ingestion of >12 g was associated with paracetamol concentration above the '200-line' in 31.8% (95% CI 27.1-36.9%) vs. 3.2% (1.9-5.2%), P < 0.0001 by chi2 proportional test, and associated with hepatotoxicity in 6.9% (4.6-10.1%) vs. 1.3% (0.5-2.8%), P = 0.0001.

CONCLUSION

Therefore, ingestion of >12 g predicted higher paracetamol exposure and increased risk of hepatotoxicity and supports the validity of patient history in this context.

Lowering serum urate does not improve endothelial function in patients with type 2 diabetes

AIMS/HYPOTHESIS

Endothelial dysfunction contributes to excess cardiovascular risk in patients with type 2 diabetes. There is strong evidence of an association between high serum uric acid concentrations and endothelial dysfunction, and uric acid has been proposed as an independent cardiovascular risk factor in type 2 diabetes. We hypothesised that lowering of uric acid concentrations might allow restoration of endothelial function in this high-risk group.

METHODS

Intravenous urate oxidase (1.5 mg) was administered to ten patients with type 2 diabetes and ten healthy participants in a two-way, randomised, placebo-controlled, crossover study. Forearm blood flow responses to intra-brachial acetylcholine, sodium nitroprusside and N(G)-monomethyl-L-arginine (L-NMMA) were measured using venous occlusion plethysmography. The augmentation index (AIx) was determined by pulse wave analysis as a measure of large arterial stiffness.

RESULTS

Acetylcholine and L-NMMA evoked lesser responses in patients with type 2 diabetes than in healthy participants. Baseline AIx was higher in patients with type 2 diabetes (mean +/- SD: 13.1 +/- 6.9%) than in healthy participants (2.0 +/- 5.1%; p = 0.006). Urate oxidase lowered serum uric acid concentrations by 64 +/- 11% (p < 0.001), but this had no effect on forearm blood flow responses or AIx in either group.

CONCLUSIONS/INTERPRETATION

Substantial short-term lowering of uric acid did not have a direct vascular effect, suggesting that, on its own, this might not be an effective strategy for restoring endothelial function in patients with type 2 diabetes.

Cardiovascular toxicity due to venlafaxine poisoning in adults: a review of 235 consecutive cases

AIMS

Venlafaxine may increase the risk of arrhythmia in certain patients. We sought to characterize the cardiovascular effects of venlafaxine overdose in adults.

METHODS

A retrospective casenote review of patients admitted to the Royal Infirmary of Edinburgh between January 2000 and June 2006. Haemodynamic and electrocardiographic data were examined in the whole group and a subset that ingested venlafaxine alone.

RESULTS

Two hundred and thirty-five patients (65 men) with median (interquartile range) age 34 years (27-43 years) had ingested venlafaxine 1500 mg (919-2800 mg). Tachycardia (40.0%), high blood pressure (28.4%) and mydriasis (36.6%) were common. Corrected QT >450 ms occurred in seven men (11.1%) and 17 women (10.5%) and transient arrhythmia in three patients. There was a positive correlation between stated quantity of venlafaxine ingested and heart rate [rho = 0.195, 95% confidence interval (CI) 0.054, 0.328] and QTc (rho = 0.314, 95% CI 0.089, 0.509).

CONCLUSIONS

Venlafaxine overdose is associated with sympathomimetic cardiovascular effects and prolonged QTc, irrespective of coingested drugs. These mechanisms might pose an increased risk of arrhythmia and require further exploration.

Glycolysis inhibitors negatively bias blood glucose measurements: potential impact on the reported prevalence of diabetes mellitus

BACKGROUND

Blood glucose concentrations are essential in defining diabetes mellitus. Recent guidelines advocate either of two discrete methods for sample collection and processing. One of these involves addition of glycolysis inhibitors, such as sodium fluoride-potassium oxalate (NaF-KOx) to sample collection tubes, whereas the other requires immediate refrigeration and sample separation.

AIMS

To examine whether the choice of the preanalytical process has any impact on subsequent glucose determinations.

METHODS

62 healthy men participated in the study during screening for diabetes. Paired venous blood samples were collected in a serum-gel tube and a tube containing NaF-KOx (both Sarstedt, Leicester, UK). Serum was promptly separated from gel tube samples and refrigerated, whereas NaF-KOx samples were not separated until immediately before analysis. Glucose concentrations were determined using an Olympus AU 2700 analyser incorporating an automated hexokinase method.

RESULTS

Mean (95% CI) glucose concentration in serum-gel tube samples was 5.2 mmol/l (5.0 to 5.4 mmol/l), whereas the concentration in tubes containing NaF-KOx was 4.9 mmol/l (4.8 to 5.1 mmol/l). A negative bias of 0.23 mmol/l (0.16 to 0.30 mmol/l) and relative negative bias of 4.7 % (3.2% to 6.3%) were observed for samples collected in NaF-KOx tubes, consistent with the combined effects of glycolysis and dilution.

CONCLUSIONS

Bias associated with the use of NaF-KOx tubes may have a significant impact on the prevalence of fasting hyperglycaemia, according to current diagnostic criteria. The small but significant difference between preanalytical processes should be considered when screening for the presence of diabetes mellitus.

Pattern of lithium exposure predicts poisoning severity: evaluation of referrals to a regional poisons unit

BACKGROUND

Lithium toxicity may result in severe clinical features. There is on-going uncertainty about the significance of serum lithium concentrations in patients with lithium toxicity.

AIM

To examine potential relationships between stated quantity of lithium ingested, serum lithium concentrations, and poisoning severity among patients referred to a regional poisons centre.

METHODS

Prospective evaluation of enquiries to the Scottish Poisons Information Bureau about lithium toxicity between 2000-2005 inclusive.

RESULTS

There were 172 enquiries, relating to acute ingestion (n = 101), acute-on-therapeutic ingestion (n = 38), or chronic poisoning (n = 33). Poisoning severity was moderate or severe in 9.9%, 26.3% (p < 0.05 vs. acute) and 54.5% (p < 0.005 vs. acute) of each group, respectively. Median (IQR) serum lithium concentrations in each group were: 2.4 (1.7-3.3) mmol/l, 2.1 (1.4-3.8) mmol/l, and 2.3 (1.9-3.3) mmol/l, respectively. The median stated quantities ingested in acute and acute-on-therapeutic lithium exposure were 5000 mg (2000-11 050 mg) and 4000 mg (2400-8820 mg), respectively.

DISCUSSION

Patients with acute-on-therapeutic and chronic poisoning are at greatest risk of severe toxicity. These differences cannot be explained by either the quantity of lithium ingested or serum lithium concentration alone.

Severe hypotension and hypothermia caused by acute ethanol toxicity

This article reports the time course and clinical features of acute ethanol poisoning in an elderly man who had previously abstained from alcohol. Several hours after ingestion, severe hypotension and hypothermia developed, and the consciousness level was reduced. Supportive measures were sufficient to allow the patient's blood pressure and temperature to recover by 24 h post ingestion. The clinical manifestations of ethanol toxicity are often confounded by coexistent drug ingestion and variable periods of unconsciousness before arrival at hospital. This case highlights that hypotension and hypothermia may be explained on the basis of severe ethanol poisoning alone, in the absence of any other contributing factors. Clinical features of poisoning may be delayed by several hours and, therefore, patients presenting at the hospital should be considered for observation for at least 4 h after consumption of potentially toxic quantities. More severe toxicity should be anticipated in patients who normally abstain from alcohol.

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.

IMPACT OF LEGISLATIVE CHANGES ON PATTERNS OF ANTIPSYCHOTIC PRESCRIBING AND SELF-POISONING IN SCOTLAND: 2000-06

Recently, national guidelines have advocated greater use of atypical rather than typical antipsychotics in the treatment of schizophrenia. In addition, there have been safety concerns regarding the potential cardiotoxicity of certain antipsychotics taken in overdose. This has led regulatory authorities in the United Kingdom to restrict the use of thioridazine. The overall impact of these legislative changes on patterns of antipsychotic prescribing has received comparatively little attention. Therefore, we sought to examine the effects on community prescribing practices, and to determine whether this was accompanied by changes in patterns of antipsychotic poisoning. Between 2000-03, there was a rapid decline in the use of typical antipsychotics, whereas the use of atypical antipsychotics increased. The prevalence of atypical and typical antipsychotic prescribing has been approximately equal between 2003-06. During the same study period, hospital admissions due to typical antipsychotic poisoning also declined, however, the effects lagged behind changes in prescribing practice by 2-3 years. These data indicate that legislative changes that restrict the use of thioridazine and other typical antipsychotics are associated with a measurable reduction in the number of hospital admissions due to overdose with these agents.

Rapid onset of haemodynamic effects after angiotensin converting enzyme-inhibitor overdose: implications for initial patient triage

BACKGROUND

Angiotensin converting enzyme (ACE)-inhibitor overdose may result in severe hypotension. Existing data do not adequately deal with the likely onset of haemodynamic effects, which has implications for the appropriate duration of monitoring in the acute-care setting. Therefore, the relationship between the interval after an ACE-inhibitor overdose and onset of hypotension was examined.

METHODS

A retrospective case review of patients who attended our institution after an ACE-inhibitor overdose between 1 January 2000 and 31 December 2005 was carried out. Data collected were heart rate, blood pressure, electrolytes, electrocardiogram variables, and interval between ingestion and lowest recorded blood pressure.

RESULTS

33 patients (24 men) who presented after an ACE-inhibitor overdose were identified. Median (interquartile range (IQR)) age was 49 (42-56) years, and stated quantity ingested was 20 (7-42) times the defined daily dose. The median (IQR) interval between ACE-inhibitor ingestion and lowest recorded systolic blood pressure was 4.5 (3.8-5.5) h, diastolic blood pressure was 3.8 (3.3-6.5) h and mean blood pressure was 4.2 (3.5-5.5) h. Heart rate did not increase substantially in response.

CONCLUSION

The lowest blood pressure was recorded within a short interval after an ACE-inhibitor overdose, irrespective of therapeutic intervention. Patients in whom hypotension has not occurred within 6 h of ingestion can be considered for discharge.

Redefining the ACE-inhibitor dose-response relationship: substantial blood pressure lowering after massive doses

OBJECTIVES

The blood pressure-lowering dose-response relationship for angiotensin converting enzyme (ACE) inhibitors is assumed to flatten at doses higher than those conventionally used in clinical practice. However, existing clinical trial data do not adequately address the haemodynamic effects of high ACE inhibitor dosages. Therefore, we examined the blood pressure responses in patients presenting to hospital following a deliberate ACE inhibitor overdose.

METHODS

The study design was a retrospective case review, and included all patients who presented to our hospital in the past 5 years after an ACE inhibitor overdose. The data collected were heart rate and systemic blood pressure at various times after ingestion and maximum haemodynamic derangement; these were compared to baseline or recovered values.

RESULTS

Data from 33 patients (24 men) were evaluated. The median (inter-quartile range, IQR) age of the patients was 49 years (IQR: 42-56 years). The median stated dose ingested was 140 mg (IQR: 60-280 mg), which is 20x (IQR: 7-42) the defined daily dose. The maximum fall in systolic blood pressure was 50 mmHg (IQR: 40-64 mmHg), diastolic blood pressure was 35 mmHg (IQR: 26-43 mmHg) and mean blood pressure was 39 mmHg (IQR: 30-47 mmHg).

CONCLUSIONS

The observed reduction in blood pressure following an overdose of an ACE inhibitor was greater than anticipated based on data from therapeutic doses. We conclude that a blood pressure-lowering dose-response relationship extends to higher ACE inhibitor doses than those conventionally used in clinical practice.

Weight loss and fatigue in an elderly patient

We report a recent clinical case of an elderly patient who presented with weight loss and fatigue and who was diagnosed with hyperthyroidism. Some time later, he was discovered to have underlying oesophageal lymphoma. The latter diagnosis was believed to contribute, at least in part, to his symptoms at the time of initial presentation. The case illustrates the potential difficulties associated with establishing the diagnosis of oesophageal lymphoma. Furthermore, symptoms of weight loss and fatigue are commonly encountered in general medical patients. This case reminded us that even when a diagnosis of hyperthyroidism has been established, these symptoms may be attributable to other pathology.

Hyperuricaemia does not impair cardiovascular function in healthy adults

OBJECTIVE

To investigate the possibility that uric acid (UA) can impair endothelial function, an important surrogate for atherosclerosis.

DESIGN

UA was administered locally or systemically to healthy adult men and women in a series of randomised placebo controlled studies. This temporarily raised serum UA concentrations, so that the potential effects of hyperuricaemia on mechanisms of cardiovascular disease could be studied.

MAIN OUTCOME MEASURES

The effects of UA administration on basal blood flow and responses to locally administered acetylcholine, sodium nitroprusside, and L-N(G)-monomethylarginine were studied in the forearm vascular bed with venous occlusion plethysmography. The effects of hyperuricaemia on systemic vascular resistance, large artery compliance, and baroreflex sensitivity were examined by validated non-invasive techniques.

RESULTS

UA administration caused a twofold increase in serum concentrations. However, there were no acute effects on haemodynamic variables, basal forearm blood flow, or nitric oxide dependent endothelial function.

CONCLUSION

Unlike other risk factors associated with endothelial dysfunction, acute exposure to high concentrations of UA does not impair cardiovascular function in healthy men. These findings do not support a causal link between hyperuricaemia and atherosclerosis.

Uric acid reduces exercise-induced oxidative stress in healthy adults

Uric acid (UA) possesses free-radical-scavenging properties, and systemic administration is known to increase serum antioxidant capacity. However, it is not known whether this protects against oxidative stress. The effects of raising UA concentration were studied during acute aerobic physical exercise in healthy subjects, as a model of oxidative stress characterized by increased circulating 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha) concentrations. Twenty healthy subjects were recruited to a randomized double-blind placebo-controlled crossover study, and underwent systemic administration of 0.5 g of UA in 250 ml of 0.1% lithium carbonate/4% dextrose vehicle or vehicle alone as control. Subjects performed high-intensity aerobic exercise for 20 min to induce oxidative stress. Plasma 8-iso-PGF2alpha concentrations were determined at baseline, after exercise and after recovery for 20 min. A single bout of high-intensity exercise caused a significant increase in plasma 8-iso-PGF2alpha concentrations from 35.0 +/- 4.7 pg/ml to 45.6 +/- 6.7 pg/ml (P<0.01). UA administration raised serum urate concentration from 293 +/- 16 to 487 +/- 16 micromol/l (P<0.001), accompanied by increased serum antioxidant capacity from 1786+/-39 to 1899 +/- 45 micromol/l (P<0.01). UA administration abolished the exercise-induced elevation of plasma 8-iso-PGF2alpha concentrations. High UA concentrations are associated with increased serum antioxidant capacity and reduced oxidative stress during acute physical exercise in healthy subjects. These findings indicate that the antioxidant properties of UA are of biological importance in vivo.

Systemic uric acid administration increases serum antioxidant capacity in healthy volunteers

Oxidative stress plays an important role in the development of atherosclerosis and contributes to tissue damage that occurs as a consequence, particularly in myocardial infarction and acute stroke. Antioxidant properties of uric acid have long been recognized and, as a result of its comparatively high serum concentrations, it is the most abundant scavenger of free radicals in humans. Elevation of serum uric acid concentration occurs as a physiologic response to increased oxidative stress-for example, during acute exercise-thus providing a counter-regulatory increase in antioxidant defenses. In view of its antioxidant properties, uric acid may have potentially important and beneficial effects within the cardiovascular system. We wished to investigate whether administration of uric acid was feasible and if it could have an impact on antioxidant function in vivo. We have, therefore, performed a randomized, placebo-controlled double-blind study of the effects of systemic administration of uric acid, 1,000 mg, in healthy volunteers, compared with vitamin C, 1,000 mg. We observed a significant increase in serum free-radical scavenging capacity from baseline during uric acid and vitamin C infusion, using two methodologically distinct antioxidant assays. The effect of uric acid was substantially greater than that of vitamin C.

Angiotropic large B-cell lymphoma with clinical features resembling subacute combined degeneration of the cord

Angiotropic large cell lymphoma is a rare neoplastic disorder associated with a high mortality. The hallmark of the disease is lymphoid proliferation confined to the intravascular compartment without local tissue or vessel wall infiltration [1]. This feature is so striking that the disease was originally thought to arise from endothelial tissue and early cases were described as malignant angioendotheliomatosis. However, application of immunohistochemical methods for detection of lymphoid markers such as the CD45 and CD20 cell surface markers has confirmed its lymphoid origin, usually of B-cell lineage [2]. Clinical manifestations of the disease are protean and are due to multifocal medium and small vessel occlusion by tumour cells [3]. Characteristic sites of involvement are skin and central nervous system and although an ante-mortem diagnosis can be made from a biopsy specimen, it is often unsuspected [4]. We present a case of angiotropic large B-cell lymphoma in a 74-year-old man who presented with urinary symptoms and had a neurological picture resembling subacute combined degeneration of the cord.

Recurrent renal cholesterol embolism

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Acute renal failure due to retroperitoneal haematoma: a question of warfarin dispensation

We report a case of an important and uncommon haemorrhagic complication in a patient receiving warfarin treatment. We reflect on the importance of close monitoring of anticoagulant therapy to prevent haemorrhagic complications and to ensure safety in longterm use.

Basic dihydromorphanthridinones with anticonvulsant activity

Some 11-alkylamino-5,6-dihydro-6-oxomorphanthridines and related compounds have been prepared and screened for anticonvulsant activity. One of the more active compounds, 11-dimethylamino-5,6-dihydro-6-oxomorphanthridine (ICI 45,337) was selected for further study and taken to clinical trial in epileptic patients.