Hospital usage of TOXBASE in Great Britain: Temporal trends in accesses 2008 to 2015.

AIM: To examine temporal trends in accesses to the UK's National Poison Information Service's TOXBASE database in Britain. METHODS: Generalized additive models were used to examine trends in daily numbers of accesses to TOXBASE from British emergency departments between January 2008 and December 2015. Day-of-the-week, seasonality and long-term trends were analysed at national and regional levels (Wales, Scotland and the nine English Government Office Regions). RESULTS: The long-term trend in daily accesses increases from 2.8 (95% confidence interval (CI): 2.6-3.0) per user on 1 January 2008 to 4.6 (95% CI: 4.3-4.9) on 31 December 2015, with small but significant differences in population-corrected accesses by region ( p < 0.001). There are statistically significant seasonal and day of the week patterns ( p < 0.001) across all regions. Accesses are 18% (95% CI: 14-22%) higher in summer than in January and at the weekend compared to weekdays in all regions; there is a 7.5% (95% CI: 6.1-8.9%) increase between Friday and Sunday. CONCLUSIONS: There are consistent in-year patterns in access to TOXBASE indicating potential seasonal patterns in poisonings in Britain, with location-dependent rates of usage. This novel descriptive work lays the basis for future work on the interaction of TOXBASE use with emergency admission of patients into hospital.

Overdose in young children treated with anti-reflux medications: Poisons enquiry evidence of excess 10-fold dosing errors with ranitidine.

BACKGROUND: Accidental drug overdose is a common problem in young children. We examined the influence of formulation and dose in enquiries for different gastro-oesophageal reflux disease treatments in children under 5 years to the UK's National Poisons Information Service. METHODS: Overdose characteristics with ranitidine, omeprazole or domperidone were compared with those of metoclopramide and the H-1 antagonist chlorphenamine, for the period 1 July 2007 to 30 June 2015. RESULTS: There were a total of 1092 ranitidine, 618 domperidone and 1193 omeprazole cases; 669, 281 and 424, respectively, were single agent enquiries; of these 77% (517) of ranitidine, 52% (145) domperidone and 32% (135) omeprazole cases occurred in children <5 years. In comparison, 17% (34/424) of metoclopramide and 53% (533/1013) of chlorphenamine were <5 years; 79% (410/517) of ranitidine overdose enquiries in children <5 years were under 6 months of age, higher than domperidone (68/145, 47%; p < 0.05), omeprazole (8/135, 6%), chlorphenamine (13/553, 2%) or metoclopramide (1/34, 3%) (all p < 0.01). In children aged <6 months, 101 were 10-fold overdoses, 86 with ranitidine. CONCLUSIONS: Tenfold overdoses in children (<5 years) were a feature of ranitidine enquiries, likely due to the high concentration of the syrup. This has relevance to other liquid formulations used for non-licenced indications in young children. Such therapeutic errors cause significant carer anxiety and healthcare utilization. Assistance is needed from manufacturers and legislators in modifying formulation so that drugs can be safely used in young children. Education of prescribers and carers is also needed to reduce the incidence of such errors that cause significant carer anxiety and healthcare utilization.

Circulating acetaminophen metabolites are toxicokinetic biomarkers of acute liver injury.

Acetaminophen (paracetamol-APAP) is the most common cause of drug-induced liver injury in the Western world. Reactive metabolite production by cytochrome P450 enzymes (CYP-metabolites) causes hepatotoxicity. We explored the toxicokinetics of human circulating APAP metabolites following overdose. Plasma from patients treated with acetylcysteine (NAC) for a single APAP overdose was analyzed from discovery (n = 116) and validation (n = 150) patient cohorts. In the discovery cohort, patients who developed acute liver injury (ALI) had higher CYP-metabolites than those without ALI. Receiver operator curve (ROC) analysis demonstrated that at hospital presentation CYP-metabolites were more sensitive/specific for ALI than alanine aminotransferase (ALT) activity and APAP concentration (optimal CYP-metabolite receiver operating characteristic area under the curve (ROC-AUC): 0.91 (95% confidence interval (CI) 0.83-0.98); ALT ROC-AUC: 0.67 (0.50-0.84); APAP ROC-AUC: 0.50 (0.33-0.67)). This enhanced sensitivity/specificity was replicated in the validation cohort. Circulating CYP-metabolites stratify patients by risk of liver injury prior to starting NAC. With development, APAP metabolites have potential utility in stratified trials and for refinement of clinical decision-making.

Comprehensive microRNA profiling in acetaminophen toxicity identifies novel circulating biomarkers for human liver and kidney injury.

Our objective was to identify microRNA (miRNA) biomarkers of drug-induced liver and kidney injury by profiling the circulating miRNome in patients with acetaminophen overdose. Plasma miRNAs were quantified in age- and sex-matched overdose patients with (N = 27) and without (N = 27) organ injury (APAP-TOX and APAP-no TOX, respectively). Classifier miRNAs were tested in a separate cohort (N = 81). miRNA specificity was determined in non-acetaminophen liver injury and murine models. Sensitivity was tested by stratification of patients at hospital presentation (N = 67). From 1809 miRNAs, 75 were 3-fold or more increased and 46 were 3-fold or more decreased with APAP-TOX. A 16 miRNA classifier model accurately diagnosed APAP-TOX in the test cohort. In humans, the miRNAs with the largest increase (miR-122-5p, miR-885-5p, miR-151a-3p) and the highest rank in the classifier model (miR-382-5p) accurately reported non-acetaminophen liver injury and were unaffected by kidney injury. miR-122-5p was more sensitive than ALT for reporting liver injury at hospital presentation, especially combined with miR-483-3p. A miRNA panel was associated with human kidney dysfunction. In mice, miR-122-5p, miR-151a-3p and miR-382-5p specifically reported APAP toxicity - being unaffected by drug-induced kidney injury. Profiling of acetaminophen toxicity identified multiple miRNAs that report acute liver injury and potential biomarkers of drug-induced kidney injury.

Impact of reducing the threshold for acetylcysteine treatment in acute paracetamol poisoning: the recent United Kingdom experience.

BACKGROUND: On 3 September 2012, the licensed indication for acetylcysteine was changed in the United Kingdom (UK) so that all patients with a plasma paracetamol concentration above a "100 mg/L" (4 h post ingestion) nomogram treatment line after an acute paracetamol (acetaminophen) overdose should be treated. This is a lower threshold than that used in the United States, Canada, Australia, and New Zealand. Here we report the impact of this change in the UK on the management of patients with acute overdose in different paracetamol concentration ranges. METHODS: This is a cohort study, consisting of a retrospective analysis conducted on prospectively collected audit data in three UK hospitals. Following appropriate ethical and data protection authority approval, data for patients presenting within 24 h of an acute timed single paracetamol overdose were extracted. Numbers of admissions and use of antidote in relation to different paracetamol concentration bands (< 100 mg/L; 100-149 mg/L; 150-199 mg/L; and ≥ 200 mg/L at 4 h) were analyzed for one-year periods before and after the change. RESULTS: Comparing the year before with the year after the change, there was no change in the numbers of patients presenting to hospital within 24 h of acute timed paracetamol overdose (1246 before and 1251 after), but more patients were admitted (759 before and 849 after) and treated with acetylcysteine (389 before and 539 after). Of the 150 additional patients treated with acetylcysteine in the year following the change, 114 (76%, 95% CI: 68.4-82.6) were in the 100-149 group and 9 (6.0%, 95% CI: 2.8-11.1) in the 150-199 group. CONCLUSIONS: Changes to national guidelines for managing paracetamol poisoning in the UK have increased the numbers of patients with acute overdose treated with acetylcysteine, with most additional treatments occurring in patients in the 100-149 mg/L dose range, a group at low risk of hepatotoxicity and higher risk of adverse reactions.

National toxicovigilance for pesticide exposures resulting in health care contact - An example from the UK's National Poisons Information Service.

BACKGROUND: Although there are extensive systems in place for pharmacovigilance, similar systems for detecting adverse health effects relating to pesticide exposure are rare. In 2004, the National Poisons Information Service (NPIS) pesticide surveillance study was implemented to identify cases requiring health care contact in the UK. This report describes the epidemiology of pesticide exposures reported to poison centres in the UK over a 9-year period. METHODS: Data on exposures were gathered through monitoring access to the NPIS's online clinical toxicology database TOXBASE(®) and through monitoring calls to the four NPIS units (Edinburgh, Cardiff, Newcastle and Birmingham). Severity was judged by both caller and NPIS staff. RESULTS: During the 9 years, 34,092 enquiries concerning pesticides were recorded; 7,804 cases of pesticide exposure were derived from these enquiries. Exposures were predominantly unintentional and acute (6,789; 87.0%); 217 (2.8%) and 755 (9.7%) were chronic unintentional and acute deliberate self-harm exposures, respectively. The majority of cases occurred in children, especially the 0-4 year age group The minimum incidence of pesticide exposure requiring health care contact was 2.0 cases/100,000 population per year. Reported numbers were 6- to 25-fold greater than those picked up through other UK pesticide toxicovigilance schemes. There were 81 cases of severe toxicity and 38 cases of fatal exposure. Deliberate self-harm accounted for 62.3% of severe cases and 79% of deaths. Aluminium phosphide, paraquat, diquat and glyphosate were responsible for most severe and fatal cases. CONCLUSIONS: The data gathered from this pesticide surveillance study indicate that poison centre resources can usefully monitor pesticide exposures resulting in health care contact in the UK. The NPIS may usefully be one component of the UK's response to European legislation requiring surveillance of complications resulting from pesticide use.

Guidelines for laboratory analyses for poisoned patients in the United Kingdom.

To enable consistency of investigation and the establishment of best practice standards, consensus guidelines were formulated previously by the UK National Poisons Information Service and the Association for Clinical Biochemistry. These joint guidelines have now been updated to reflect current best practice. The types of laboratory investigation required for poisoned patients are categorized as either (a) essential common laboratory investigations or (b) specific toxicological assays, and also as either (i) common or (ii) specialist or infrequent. Tests in categories (a) and (bi) should be available 24 hours per day, with a maximum turnaround time of 2 h. For the specialist assays, i.e. category (bii), availability and turnaround times have been specified individually. The basis for selection of these times has been clinical utility. The adoption of these guidelines, along with the use of the National Poisons Information Service (0844 8920111) and its online poisons information resource TOXBASE(®) (www.toxbase.org) enable the poisoned patient to receive appropriate, 'best practice' investigations according to their clinical needs and will avoid unnecessary investigations.

The predictive value of hospital admission serum alanine transaminase activity in patients treated for paracetamol overdose.

BACKGROUND: Paracetamol is a major cause of poisoning. Treatment decisions are predominately based on the dose ingested and a timed blood paracetamol concentration because most patients present to hospital soon after overdose, before hepatotoxicity can be confirmed/excluded using serum alanine transaminase (ALT). Nonetheless, ALT is measured at hospital presentation; we investigated its value in predicting hepatotoxicity. METHODS: From March 2011 to May 2012, patients admitted to the Royal Infirmary of Edinburgh for paracetamol overdose treatment were identified. We determined the value of admission ALT (below or above our upper limit of normal-50 IU/l) at predicting three endpoints: 1-doubling of ALT; 2-peak ALT >1000 IU/l; 3-peak international normalized ratio (INR) >2. RESULTS: From 500 patients, 410 met the entry criteria; 264 presented within 8 h of overdose, 54 between 8 and 24 h, 53 after 24 h and 39 were staggered ingestions. Admission ALT was increased in 71. For endpoint 1 (ALT doubling), the positive predictive value (PPV) of admission ALT was 19% [95% confidence interval (CI) 12-30] with a negative predictive value (NPV) of 98% (95% CI 96-99); endpoint 2 (ALT >1000 IU/l: PPV 23% (95% CI 14-34) and NPV 100% (95% CI 99-100) and for endpoint 3 (INR >2): PPV 14% (95% CI 7-25) and NPV of 100% (95% CI 99-100). The NPV remained high when only late presenters were included. CONCLUSION: Admission ALT within the normal range has a high NPV and could be used, alone or in combination with newer biomarkers, to identify lower risk patients at hospital presentation.

The use of atropine in a nerve agent response with specific reference to children: are current guidelines too cautious?

This review examines the potential use of nerve agents by a terrorist organisation against a civilian population, which has become an increasingly apparent threat in the UK. Present guidelines for the use of atropine, particularly in children, following such an event are unclear. No precise agreement exists on the most appropriate dose of atropine, or the frequency with which it should be administered. This uncertainty leaves children vulnerable as potentially life-saving treatment may be crucially delayed. Guidelines must be standardised to allow rapid antidotal delivery and maximise the potential for survivors. This review examines the issues currently surrounding the use of atropine in children following a nerve agent attack and propose strategies for treating exposed children.

Interpretation of clinical guidelines for poisoned patients: positive and negative effects of standard phrases used in TOXBASE.

INTRODUCTION: Electronic information sources are increasingly relied upon for clinical management advice. TOXBASE is a standardised online resource that offers clinical advice on the management of poisoned patients and is the first point of contact between clinicians and the National Poisons Information Service in the United Kingdom. Advice is delivered using a series of standard phrases. The present study examined how healthcare professionals interpret the phrases and studied their impact on clinical decision-making. METHODS: A structured prospective written questionnaire was offered to healthcare staff in the Lothian region, and an electronic questionnaire issued to TOXBASE users across the United Kingdom. Participants were asked to respond to a variety of scenarios representing acutely poisoned patients. Clinical management advice was offered via TOXBASE using a variety of standard phrases, and participants were asked to express the likelihood that they would then administer gut decontamination treatment. RESULTS: There were 70 respondents to written questionnaires, and 119 respondents to the electronic version. Phrases that included didactic instructions, for example 'give', 'contraindicated', 'do' and 'perform' were associated with strongly positive or strongly negative responses. In contrast, advice that consisted of open phrases such as 'consider', 'benefit uncertain', and 'few data' were associated with inconsistent responses. CONCLUSION: Didactic words and phrases are associated with more consistent interpretation and response than open-ended words and phrases. The choice of words and phrases used in electronic systems can have an independent impact on clinical decision-making and require further consideration.

Adverse reactions associated with acetylcysteine.

INTRODUCTION: Paracetamol (acetaminophen) is one of the most common agents deliberately ingested in self-poisoning episodes and a leading cause of acute liver failure in the western world. Acetylcysteine is widely acknowledged as the antidote of choice for paracetamol poisoning, but its use is not without risk. Adverse reactions, often leading to treatment delay, are frequently associated with both intravenous and oral acetylcysteine and are a common source of concern among treating physicians. METHODS: A systematic literature review investigating the incidence, clinical features, and mechanisms of adverse effects associated with acetylcysteine. RESULTS: A variety of adverse reactions to acetylcysteine have been described ranging from nausea to death, most of the latter due to incorrect dosing. The pattern of reactions differs with oral and intravenous dosing, but reported frequency is at least as high with oral as intravenous. The reactions to the intravenous preparation result in similar clinical features to true anaphylaxis, including rash, pruritus, angioedema, bronchospasm, and rarely hypotension, but are caused by nonimmunological mechanisms. The precise nature of this reaction remains unclear. Histamine now seems to be an important mediator of the response, and there is evidence of variability in patient susceptibility, with females, and those with a history of asthma or atopy are particularly susceptible. Quantity of paracetamol ingestion, measured through serum paracetamol concentration, is also important as higher paracetamol concentrations protect patients against anaphylactoid effects. Most anaphylactoid reactions occur at the start of acetylcysteine treatment when concentrations are highest. Acetylcysteine also affects clotting factor activity, and this affects the interpretation of minor disturbances in the International Normalized Ratio in the context of paracetamol overdose. CONCLUSION: This review discusses the incidence, clinical features, underlying pathophysiological mechanisms, and treatment of adverse reactions to acetylcysteine and identifies particular "at-risk" patient groups. Given the commonality of adverse reactions associated with acetylcysteine, it is important to ensure that any adverse event does not preclude patients from receiving maximal hepatic protection, particularly in the context of significant paracetamol ingestion. Further work on mechanisms should allow specific therapies to be developed.

Patterns and predictors of re-admission to hospital with self-poisoning in Scotland.

OBJECTIVES: To identify factors influencing hospital re-admission with self-poisoning. STUDY DESIGN: Retrospective cohort follow-up study using national linked hospital discharge data. METHODS: All Scottish adult hospital episodes with self-poisoning admissions were captured using NHS Scotland Information Services Division data, and first-time 'index' admissions between 1996 and 2002 were identified. Re-admission rate was defined as the proportion of index admissions who went on to have one or more further self-poisoning admissions within 2 years. The effects of various potential risk factors for re-admission were examined using logistic regression. RESULTS: In total, 50,891 index admissions were identified; of these, 8278 patients were re-admitted. The 1-year re-admission rate was 12.2%. Older patients (>65 years) were least likely to be re-admitted [odds ratio (OR) 0.40, P<0.01, compared with patients aged 15-24 years]. No differences were found between males and females. Previous psychiatric hospital admission was associated with an increased re-admission rate (OR 2.85, P<0.01), with a diagnosis of personality disorder associated with the highest rate of re-admission (OR 4.59, P<0.01). Other factors predicting re-admission were: increased deprivation (quintile 3: OR 1.16, P<0.01; quintile 5: OR 1.15, P<0.01, compared with quintile 1); taking medicines for chronic disease, drug dependency (OR 1.6 and 1.19, P < or = 0.02) or antidepressants (OR 1.11, P=0.01) (compared with paracetamol); and co-ingestion of three or more agents (OR 1.37, P<0.01). CONCLUSION: Younger age, higher deprivation, ingestion of certain drug groups or multiple drug types, and prior psychiatric hospital admission are all risk factors for re-admission with self-poisoning. Personality disorder carried the greatest risk of re-admission. These findings may provide a basis to develop policies to reduce re-admission rates in the future.

UK childhood exposures to pesticides 2004-2007: a TOXBASE toxicovigilance study.

OBJECTIVE: There are no systematic methods for toxicovigilance of non-medicinal products in the UK. This is particularly relevant for pesticides, where there is significant public concern about potential adverse effects. This study describes a prospective toxicovigilance scheme based on follow-up of enquiries to the National Poisons Information Service (NPIS) through its online poisons information system TOXBASE. These enquiries reflect acute exposures and the patterns of acute illness that result. RESULTS: A total of 10 061 pesticide-related enquiries were identified. After follow-up, data were gathered on 2364 suspected exposures, of which 1162 involved children. After exclusions, 1147 exposures are reported here. No deaths were reported and only 37 children were admitted to hospital. The majority were considered to have either minimal or no features (925, 80.6%). Symptoms for 38 children were unknown. Symptoms reported in the other 184 children included nausea or vomiting (58), eye irritation, pain or conjunctivitis (29), skin irritation (28), abdominal pain (24), mouth or throat irritation (18) and diarrhoea (15). Where age was recorded, 60.5% (680) of children involved in suspected pesticide exposures were aged 2 years or less. The most common scenario for acute accidental exposure to pesticide in children was exposure after application (329, 28.7%) or due to poor storage (228, 19.9%). CONCLUSIONS: Areas of potential concern identified included storage, access of young children to "laid" baits and pesticides, and exposures as a result of medication errors, with liquid head lice preparations being confused with other medicines. Use of NPIS systems provides a potentially useful method of toxicovigilance.

Renal injury at first presentation as a predictor for poor outcome in severe paracetamol poisoning referred to a liver transplant unit.

BACKGROUND: Paracetamol poisoning remains a leading cause of morbidity and mortality. Identifying indices of poor prognosis at first presentation is key to both improving clinical care and determining targets for intervention. Renal failure is a feature of severe paracetamol poisoning. The aim of this study was to investigate the relationship between renal function (serum creatinine, Cr) at first hospital presentation and time of tertiary referral to outcomes in severe paracetamol poisoning. METHODS: This was a retrospective cohort analysis of patients referred to the Scottish Liver Transplant Unit due to paracetamol poisoning between 1992 and 2004. The relation between degree of renal injury and outcomes, including worst prothrombin time, Kings College Hospital Criteria (KCHC) and death were examined. The effects of age, nature (single or multiple) and stated size of overdose, hepatic enzyme induction (gamma-glutamyl transpeptidase, GGT), degree of liver injury (aspartate aminotransferase, prothrombin time), blood pressure and renal injury were assessed. RESULTS: Data from 522 patients were included. Renal impairment (Cr >120 mmol/l) was present in 48.8% of patients with liver injury at time of first presentation. Creatinine at first admission predicted poorer outcome in terms of worse prothrombin time, KCHC and death (p < 0.001). Associated risk factors for renal dysfunction included later presentation, staggered ingestion, increased age, hypotension and elevated GGT at first admission. CONCLUSIONS: Creatinine at first admission appears to be a predictor of poor outcome in paracetamol overdose. A better understanding of mechanisms involved in causing renal dysfunction may offer potential therapeutic targets for improving outcome in this common poisoning.

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.

Impaired heart rate variability and altered cardiac sympathovagal balance after antidepressant overdose.

PURPOSE: Antidepressant overdose may be associated with significant cardiotoxicity, and recent data have shown that acute toxic effects are associated with impaired heart rate variability. This study was designed to examine the feasibility of non-invasive heart rate variability recording in patients that present to hospital after deliberate antidepressant ingestion. METHODS: This was a prospective study of 72 consecutive patients attending the Emergency Department after deliberate antidepressant overdose and 72 age-matched patients that ingested paracetamol, as a control group. Single time-point continuous electrocardiographic recordings were used to allow spectral analyses of heart rate variability determined in low-frequency (LF) and high-frequency (HF) domains. The LF:HF ratio was used to represent overall sympathovagal cardiac activity. RESULTS: Antidepressant overdose was associated with reduced overall heart rate variability: 1329 vs. 2018 ms(2) (P = 0.0239 by Mann-Whitney test). Variability in the LF domain was higher (64.8 vs. 49.8, P = 0.0006), whereas that in the HF domain was lower (24.3 vs. 36.4, P = 0.0001), and the LF:HF ratio was higher in the antidepressant group (2.4 vs. 1.2, P = 0.0003). CONCLUSIONS: Antidepressant overdose is associated with impaired heart rate variability in a pattern consistent with excess cardiac sympathetic activity. Further work is required to establish the significance of these findings and to explore whether the impairment of heart rate variability may be used to predict the development of arrhythmia in this patient group.

EJCP and clinical toxicology: the first 40 years.

INTRODUCTION: The European Journal of Clinical Pharmacology is now 40 years old and its history and development parallel developments in the related discipline of clinical (medical) toxicology. The journal has published many papers over its history that have informed its readers of scientific advances that link clinical pharmacology and clinical toxicology. DISCUSSION: This review will provide an overview of the developments in treatment of poisoning and how effects of poisoning may provide information for drug regulation and suggests ways in which developments in pharmacogenetics and metabolomics may stimulate future research in this area.

Survey of cases of paracetamol overdose in the UK referred to National Poisons Information Service (NPIS) consultants.

BACKGROUND: Paracetamol is the most common means of drug overdose in the UK. Guidance on management is available to junior doctors through TOXBASE, the online resource managed by the UK National Poisons Information Service (NPIS) and in poster form. TOXBASE is supported by NPIS units and further by a UK national rota of clinical toxicologists. A study was undertaken to examine reasons why calls about paracetamol are referred to consultants to better understand issues in managing this common poisoning. METHODS: Calls relating to paracetamol overdose referred by a poisons information specialist to the duty NPIS consultant between 1 May 2005 and 30 April 2006 were identified from the database and the number of TOXBASE accesses during the same time period was determined. Enquiries that resulted in consultant referral were classified into six categories. RESULTS: Calls referred to NPIS consultants pertain mainly to patients who present late, staggered overdoses, adverse reactions to N-acetylcysteine, and interpretation of blood results. This information has been used to inform the development of TOXBASE so that comprehensive advice is readily available to end users. CONCLUSIONS: The operation of a national consultant rota enables information on difficult or unusual cases of poisoning to be pooled so that treatment guidelines can be developed to optimise treatment throughout the UK.