Hepatotoxicity despite early administration of intravenous N-acetylcysteine for acute acetaminophen overdose

OBJECTIVES

The objective was to evaluate the effectiveness of intravenous N-acetylcysteine (IV NAC; 300 mg/kg over 21 hours) in early acute acetaminophen (APAP) overdose patients.

METHODS

This observational case series included patients hospitalized between 2004 and 2007 for acute APAP overdoses and who were reported to a regional poison center. Inclusion criteria were plasma APAP concentrations on or above the treatment line on the Rumack-Matthew nomogram, administration of IV NAC within 8 hours of ingestion, and follow-up to known outcome. The hospital chart of each patient who received IV NAC for longer than the standard 21 hours was reviewed. Hepatotoxicity was defined as hepatic aminotransferase levels greater than 1,000 IU/L.

RESULTS

Seventy-seven patients met inclusion criteria and received at least 21 hours of IV NAC for an acute APAP overdose. Seven patients received antidotal therapy for greater than 21 hours. These patients tended to have ingested combination preparations, have very high initial plasma APAP concentrations, and had persistently elevated plasma concentrations during their hospital stay. Hepatotoxicity occurred in 4 patients (5.2%, 95% confidence interval [CI] = 0.2% to 10.1%), including 1 death and 1 liver transplantation.

CONCLUSIONS

Hepatotoxicity developed in 5.2% of cases, suggesting that the 21-hour IV NAC regimen is suboptimal in some patients. In addition to high initial plasma APAP concentrations, APAP product formulation and persistently elevated plasma APAP concentrations were identified as factors possibly associated with developing hepatotoxicity. The authors propose a tailored approach to the discontinuation of IV NAC and point out the need for reevaluation of optimal doses and duration of therapy.

Comparison of toxicity of acute overdoses with citalopram and escitalopram

BACKGROUND

Seizures and QTc prolongation are associated with citalopram poisoning; however, overdose experience with escitalopram is more limited.

OBJECTIVES

The goals of this study were to compare citalopram's vs. escitalopram's clinical effects in overdose, including the incidence of seizures.

METHODS

A retrospective review was conducted for single-substance acute overdoses with citalopram and escitalopram, managed in hospitals, that were reported to six U.S. poison centers from 2002-2005.

RESULTS

There were 374 citalopram and 421 escitalopram overdose cases. Gender and ages were similar between the two, with 68-70% females and a median age of 20 years for citalopram and 18 years for escitalopram. Median dose by history was 310 mg for citalopram and 130 mg for escitalopram. More serious outcomes were associated with citalopram overdoses (p < 0.001). Most frequently reported clinical effects with citalopram and escitalopram were tachycardia, drowsiness, hypertension, and vomiting. Seizures (30 vs. 1, respectively, p < 0.001) and tremor (32 vs. 13, respectively, p = 0.001) were more common with citalopram. QTc prolongation occurred in 14 citalopram cases and 7 escitalopram cases (p = 0.109). There was an association between increasing dose and severity of outcome for citalopram (p < 0.001) and escitalopram (p = 0.011). In children < 6 years old, 12 of 66 citalopram and 5 of 57 escitalopram cases experienced toxicity, such as drowsiness, nausea/vomiting, and tachycardia. There were no seizures in this age group.

CONCLUSIONS

Escitalopram seems to be less toxic than citalopram after an acute overdose; seizures and tremors were more common with citalopram. Initial management of overdoses should include seizure precautions for citalopram and cardiac monitoring for both drugs.

Frequency of medication errors with intravenous acetylcysteine for acetaminophen overdose

BACKGROUND

Acetadote, an intravenous preparation of acetylcysteine, became commercially available in the US in June 2004 for the treatment of acetaminophen poisoning. The dosing regimen is complex, consisting of a loading dose followed by 2 maintenance doses, each with different infusion rates.

OBJECTIVE

To analyze the frequency of medication errors related to the complex dosing regimen for intravenous acetylcysteine.

METHODS

A retrospective chart review of a regional poison center's records was performed for all patients treated with intravenous acetylcysteine from August 1, 2006, to August 31, 2007. Data collected included acetylcysteine dose, infusion rate, interruptions in therapy, unnecessary administration, and medical outcome. Records that revealed medication errors were further examined for the time and location of the errors.

RESULTS

There were 221 acetaminophen overdose cases treated with intravenous acetylcysteine that met inclusion criteria. Of these, 84 medication errors occurred in 74 (33%) patients. The frequency and types of errors were 1.4% incorrect dose, 5% incorrect infusion rate, 18.6% more than 1 hour of interruption in therapy, and 13.1% unnecessary administration. The frequency and types of medication errors in pediatric patients were similar to those in the total patient population. Errors occurred most frequently in the emergency department compared with intensive care units or general medical floors. In addition, errors occurred most frequently on third shift, compared with first or second shift. Evaluation of medical outcomes in cases involving acetaminophen only found that medication errors did not have an impact on coded outcomes.

CONCLUSIONS

Medication administration errors occur frequently with intravenous acetylcysteine. Awareness of this problem, coupled with increased vigilance in identifying factors associated with errors, should decrease medication errors with intravenous acetylcysteine therapy for acetaminophen poisoning.

Toxicity of buprenorphine overdoses in children

OBJECTIVE

There are few reports in children of overdoses of buprenorphine, a partial opioid agonist used in the treatment of opioid dependence and pain. The purpose of this study was to analyze buprenorphine overdoses in young children reported by US poison centers to the Researched Abuse, Diversion, and Addiction-Related Surveillance System.

METHODS

A retrospective review of buprenorphine overdoses in children < 6 years of age reported to the Researched Abuse, Diversion, and Addiction-Related Surveillance System from November 2002 through December 2005 was performed. Patients lost to follow-up and those ingesting multiple substances were excluded.

RESULTS

Eighty-six cases met inclusion criteria. In the 54 children who developed toxicity, the clinical effects included drowsiness or lethargy (55%), vomiting (21%), miosis (21%), respiratory depression (7%), agitation or irritability (5%), pallor (3%), and coma (2%). There were no fatalities. The mean time to onset of effects was 64.2 minutes, with a range of 20 minutes to 3 hours. Duration of clinical effects was under 2 hours in 11%, 2 to 8 hours in 59%, 8 to 24 hours in 26%, and > 24 hours in 4%. Children who ingested > or = 2 mg of buprenorphine were more likely to experience clinical effects, and all of the children who ingested > 4 mg experienced some effect. No child ingesting < 4 mg experienced a severe effect. Of the 22 children administered naloxone, 67% had at least a partial response.

CONCLUSIONS

Buprenorphine overdoses are generally well tolerated in children, with significant central nervous system and respiratory depression occurring in only 7%. Any child ingesting > 2 mg and children < 2 years of age ingesting more than a lick or taste should be referred to the emergency department for a minimum of 6 hours of observation. Naloxone can be used to reverse respiratory depression.

Prospective observational multi-poison center study of ziprasidone exposures

BACKGROUND

Ziprasidone is an atypical antipsychotic associated with QTc prolongation during therapeutic use. We characterized the clinical manifestations associated with ziprasidone overdoses, in particular the incidence and severity of QTc prolongation.

METHODS

Four regional poison centers prospectively collected ziprasidone overdose data from August 1, 2003 to October 1, 2005. Cases were included if they were followed to known medical outcome and comprised single-substance ziprasidone exposures or with co-ingestants not associated with prolongation of the QTc interval.

RESULTS

Fifty-six ziprasidone exposures met inclusion criteria. The most common clinical effects were drowsiness (N=38, 67.9%) and tachycardia (N=19, 33.9%). QTc prolongation (>0.500 second) occurred in only one patient. Seven patients had QTc intervals of 0.450 to 0.500 second. Medical outcomes were coded as no effect (13, 23.2%), minor effect (21, 35.5%), moderate effect (20, 35.7%), or major effect (2, 3.4%).

CONCLUSION

Common clinical effects following ziprasidone overdose are drowsiness and tachycardia. Clinically significant QTc prolongation occurs infrequently.

Polypharmacy and the geriatric patient

The older adult population is increasing and with it, the risk of polypharmacy. Multiple physicians treating one patient, increasing comorbidities, and an increase in the variety of drugs available contribute to the adverse effects of polypharmacy on the elderly patient. Application of Beers criteria, appropriate therapeutic drug monitoring, and careful, periodic review of the patient's medication list will assist with preventing the sometimes lethal complications of polypharmacy.

2005 Annual Report of the American Association of Poison Control Centers' national poisoning and exposure database

BACKGROUND

The American Association of Poison Control Centers (AAPCC; <a href="http://www.aapcc.org" target="BLANK">http://www.aapcc.org</a>) maintains the national database of information logged by the country's 61 Poison Control Centers (PCCs). Case records in this database are from self-reported calls: they reflect only information provided when the public or healthcare professionals report an actual or potential exposure to a substance (e.g., an ingestion, inhalation, or topical exposure.), or request information/educational materials. Exposures do not necessarily represent a poisoning or overdose. The AAPCC is not able to completely verify the accuracy of every report made to member centers. Additional exposures may go unreported to PCCs, and data referenced from the AAPCC should not be construed to represent the complete incidence of national exposures to any substance(s). U.S. Poison Centers make possible the compilation and reporting of this report through their staffs' meticulous documentation of each case using standardized definitions and compatible computer systems. The 61 participating poison centers in 2005 are: Regional Poison Control Center, Birmingham, AL; Alabama Poison Center, Tuscaloosa, AL; Arizona Poison and Drug Information Center, Tucson, AZ; Banner Poison Control Center, Phoenix, AZ; Arkansas Poison and Drug Information Center, Little Rock, AK; California Poison Control System-Fresno/Madera Division, CA; California Poison Control System-Sacramento Division, CA; California Poison Control System-San Diego Division, CA; California Poison Control System-San Francisco Division, CA; Rocky Mountain Poison and Drug Center, Denver, CO; Connecticut Poison Control Center, Farmington, CT; National Capital Poison Center, Washington, DC; Florida Poison Information Center, Tampa, FL; Florida Poison Information Center, Jacksonville, FL; Florida Poison Information Center, Miami, FL; Georgia Poison Center, Atlanta, GA; Illinois Poison Center, Chicago, IL; Indiana Poison Center, Indianapolis, IN; Iowa Statewide Poison Control Center, Sioux City, IA; Mid-America Poison Control Center, Kansas City, KA; Kentucky Regional Poison Center, Louisville, KY; Louisiana Drug and Poison Information Center, Monroe, LA; Northern New England Poison Center, Portland, ME; Maryland Poison Center, Baltimore, MD; Regional Center for Poison Control and Prevention Serving Massachusetts and Rhode Island, Boston, MA; Children's Hospital of Michigan Regional Poison Control Center, Detroit, MI; DeVos Children's Hospital Regional Poison Center, Grand Rapids, MI; Hennepin Regional Poison Center, Minneapolis, MN; Mississippi Regional Poison Control Center, Jackson, MS; Missouri Regional Poison Center, St Louis, MO; Nebraska Regional Poison Center, Omaha, NE; New Jersey Poison Information and Education System, Newark, NJ; New Mexico Poison and Drug Information Center, Albuquerque, NM; New York City Poison Control Center, New York, NY; Long Island Regional Poison and Drug Information Center, Mineola, NY; Ruth A. Lawrence Poison and Drug Information Center, Rochester, NY; Upstate (formerly Central) New York Poison Center, Syracuse, NY; Western New York Poison Center, Buffalo, NY; Carolinas Poison Center, Charlotte, NC; Cincinnati Drug and Poison Information Center, Cincinnati, OH; Central Ohio Poison Center, Columbus, OH; Greater Cleveland Poison Control Center, Cleveland, OH; Oklahoma Poison Control Center, Oklahoma City, OK; Oregon Poison Center, Portland, OR; Pittsburgh Poison Center, Pittsburgh, PA; The Poison Control Center, Philadelphia, PA; Puerto Rico Poison Center, San Juan, PR; Palmetto Poison Center, Columbia, SC; Tennessee Poison Center, Nashville, TN; Central Texas Poison Center, Temple, TX; North Texas Poison Center, Dallas, TX; Southeast Texas Poison Center, Galveston, TX; Texas Panhandle Poison Center, Amarillo, TX; West Texas Regional Poison Center, El Paso, TX; South Texas Poison Center, San Antonio, TX; Utah Poison Control Center, Salt Lake City, UT; Virginia Poison Center, Richmond, VA; Blue Ridge Poison Center, Charlottesville, VA; Washington Poison Center, Seattle, WA; West Virginia Poison Center, Charleston, WV; Wisconsin Poison Center, Milwaukee, WI.

Efficacy of activated charcoal administered more than four hours after acetaminophen overdose

To evaluate whether administration of activated charcoal, in addition to standard N-acetylcysteine (NAC) therapy, after acetaminophen overdose provides additional patient benefit over NAC therapy alone, a 1-year non-randomized prospective, multi-center, observational case series was performed at three poison centers and one poison center system. Entrance criteria were all acute acetaminophen overdoses with: 1) an acetaminophen blood concentration determined to be in the toxic range by the Rumack-Matthew nomogram; and 2) all therapies, including NAC and activated charcoal, initiated between 4 and 16 h post-ingestion. There were 145 patients meeting entrance criteria, of whom 58 patients (40%) received NAC only and 87 patients (60%) received NAC and activated charcoal. Overall, 23 patients had elevations of AST or ALT greater than 1000 IU/L, of which 21 patients received NAC only (38% of total NAC only group) and 2 patients received NAC and activated charcoal (2% of total NAC+AC group). Administration of activated charcoal in this series of patients with toxic acetaminophen concentrations treated with NAC was associated with reduced incidence of liver injury, as measured by elevated serum transaminases and prothrombin times.

Evaluation of toxicity of topiramate exposures reported to poison centers

Published literature on the toxicity of a topiramate overdose is limited to case reports. This retrospective study of poison center data was performed to examine the severity of topiramate overdoses. Data on single substance exposures to topiramate reported to the American Association of Poison Control Centers (AAPCC) Toxic Exposure Surveillance System (TESS) in 2000 and 2001 were retrospectively analysed. A total of 567 cases met the inclusion criteria, of which 39% occurred in adults over 19 years of age and 30.2% in children < or = 4 years old. The majority of patients (62.1%) experienced no toxicity. The most common clinical effects reported were drowsiness/lethargy (15.5%), dizziness/vertigo (4.9%), agitation (4.9%), confusion (3.9%), nausea (2.6%) and vomiting (2.5%). Symptomatic patients were older than asymptomatic patients and adults were more likely to be managed in a healthcare facility (P <0.0001). Patients who received gastrointestinal decontamination experienced less serious outcomes than those without decontamination (P <0.02). It is concluded that clinicians should expect relatively mild mental status changes in adults or children with toxicity from topiramate overdose. Serious toxic effects, such as CNS depression with respiratory depression or persistent non-anion gap metabolic acidosis, are infrequent.

Are 1–2 dangerous? Chloroquine and hydroxychloroquine exposure in toddlers

Ingestion of 1-2 tablets of chloroquine or hydroxylchloroquine is thought to predispose children under 6 years of age to serious morbidity and mortality. The actual risk to the toddler and appropriate guidelines for care remain unclear at a time when both medications are therapeutically utilized as anti-inflammatory agents in addition to their main use as anti-parasitics. A review of the literature and data from the American Association of Poison Control Centers reveals instances where exposure to as little as 1-2 tablets of chloroquine resulted in serious consequences. Based on these findings, ingestions of greater than 10 mg/kg of chloroquine base or unknown amounts require triage to the nearest health care facility for 4-6 h of observation. There is very limited data on pediatric hydroxychloroquine overdoses and no reports of toxicity from 1-2 pills, but given its similarity to chloroquine, it also should be considered potentially toxic at small doses. Thus, similar recommendations should be followed for triage after accidental hydroxychloroquine overdose.

High-Dose Insulin Therapy for Calcium-Channel Blocker Overdose

OBJECTIVE:

To evaluate the evidence for using high-dose insulin therapy with supplemental dextrose and potassium in calcium-channel blocker (CCB) overdose.

DATA SOURCES:

Evidence of efficacy for high-dose insulin therapy with supplemental dextrose and potassium was sought by performing a search of MEDLINE and Toxline between 1966 and July 2004 using combinations of the terms calcium-channel blocker, overdose, poisoning, antidote, and insulin. Abstracts from the North American Congress of Clinical Toxicology for the years 1996–2003 were also reviewed.

STUDY SELECTION AND DATA EXTRACTION:

Identified articles, including animal studies, case reports, and case series, were evaluated for this review. No clinical trials were available.

DATA SYNTHESIS:

Animal models of CCB overdose demonstrate that high-dose insulin with supplemental dextrose and potassium was a more effective therapy than calcium, glucagon, or catecholamines. High-dose insulin appears to enhance cardiac carbohydrate metabolism and has direct inotropic effects. Published clinical experience is limited to 13 case reports where insulin was used after other therapies were failing; 12 of these patients survived. High-dose insulin therapy was beneficial for CCB-induced hypotension, hyperglycemia, and metabolic acidosis. Bradycardia and heart block resolved in some patients, but persisted in others.

CONCLUSIONS:

Based on animal data and limited human experience, as well as the inadequacies of available alternatives for patients with significant poisoning, high-dose insulin therapy warrants further study and judicious use in patients with life-threatening CCB poisoning.

Toxic clonidine ingestion in children

OBJECTIVES

We performed a prospective case series to seek dosage or clinical parameters to better identify patients who need direct medical evaluation.

STUDY DESIGN

All clonidine ingestions in children younger than 12 years of age reported to 6 poison centers were followed for a minimum of 24 hours. Exclusion criterion was polydrug ingestion.

RESULTS

The study included 113 patients, of whom 63 were male. Mean age was 3.8 years (+/-2.4 SD). Clinical effects were common, but severe adverse effects occurred in <10% of patients. The dose ingested was reported for 90 patients (80%); 61 (68%) children ingested <0.3 mg and none had coma, respiratory depression, or hypotension. The lowest dose ingested by history with coma and respiratory depression was 0.3 mg (0.015 mg/kg). Prior clonidine therapy did not affect outcome. Onset of full clinical effects in all cases was complete within 4 hours of ingestion.

CONCLUSIONS

We recommend direct medical evaluation for (1) all children 4 years of age and younger with unintentional clonidine ingestion of >or=0.1 mg, (2) ingestion of >0.2 mg in children 5 to 8 years of age, and (3) ingestion of >or=0.4 mg in children older than 8 years of age. Observation for 4 hours may be sufficient to detect patients who will develop severe effects.

Atypical experience: a case series of pediatric aripiprazole exposures

BACKGROUND

Aripiprazole is a new psychotropic agent that possesses a unique pharmacologic profile. The drug demonstrates mixed dopamine and serotonin agonist-antagonist activity and has been labeled a third-generation antipsychotic and dopamine-serotonin system stabilizer. Overdose experience is limited, especially in pediatrics.

CASE SERIES

Of five pediatric cases identified, toxicity was mainly evident in younger patients. A 2-year-old who ingested 40 mg experienced vomiting and significant lethargy lasting approximately 30 h. A 6-year-old who received two doses of aripiprazole therapeutically experienced lethargy, drooling, and flaccid facial muscles which improved with diphenhydramine. Two adolescents remained asymptomatic despite doses of 120 mg and 300 mg while a third adolescent with an unknown dose experienced transient lethargy.

CONCLUSION

Aripiprazole is capable of producing marked lethargy and gastrointestinal upset in pediatric patients. Adolescents in this series experienced only minor, if any, clinical effects. Major clinical effects, i.e., seizures, dysrhythmias, were not reported in this series.

Evaluation of lamotrigine toxicity reported to poison centers

BACKGROUND

Lamotrigine is an antiepileptic drug for the treatment of partial and generalized seizures as well as bipolar disorder. Limited published information exists describing the clinical effects of lamotrigine overdose.

OBJECTIVE

To examine the toxicity of exposures to lamotrigine utilizing national poison center data.

METHODS

Data on single-substance exposures to lamotrigine reported to the American Association of Poison Control Centers Toxic Exposure Surveillance System in 2000 and 2001 were retrospectively analyzed.

RESULTS

There were 493 cases that met the inclusion criteria. The majority of exposures occurred within the age groups 20-59 years old (n = 198, 40.2%), followed by </=4 years old (n = 173, 35.1%). Overall, the majority of patients (52.1%) exposed to lamotrigine in overdose experienced no toxic clinical effects. The most common clinical effects reported in overdose were drowsiness/lethargy (20.9%), vomiting (11%), nausea (5.1%), ataxia (4.9%), dizziness/vertigo (4.5%), and tachycardia (4.3%). Major clinical effects included coma (n = 6), seizures (n = 8), and respiratory depression (n = 3). Medical outcome was reported as minor in 150 (30.4%), moderate in 73 (14.8%), and major in 13 (2.6%) cases. There were no deaths.

CONCLUSIONS

These data demonstrate that the majority of patients exposed to lamotrigine in overdose experienced minor or no clinical effects. Although rare, serious effects can also occur.

Characterization of gabapentin overdose using a poison center case series

BACKGROUND

Gabapentin is an anticonvulsant that is being used for an increasing number of off-label indications. The purpose of this study is to document the clinical manifestations and outcomes of gabapentin exposures reported to poison centers.

METHODS

A multicenter prospective observational study of all gabapentin exposures reported to three poisoncenters was conducted between 4/1/98 and 4/1/2000. Cases involving gabapentin only were evaluated.

RESULTS

There were 20 cases with gabapentin as the sole substance in doses ranging from 50 mg to 35 g. Ten of the 20 cases involved children and adolescents. Clinical effects developed early and resolved within 10 hours in most patients. Seven cases were managed in the home with only observation. Four of these patients remained asymptomatic. Effects reported in the three symptomatic patients were drowsiness (3) and ataxia (1). Thirteen patients were managed in a health care facility. Nine were symptomatic with reported effects of drowsiness (6), dizziness (3), nausea/vomiting (2), tachycardia (2), and hypotension (2). None of the patients were admitted for medical care.

CONCLUSION

In this cases series, gabapentin exposures caused no or minimal toxicity.

Pediatric methylphenidate exposures: 7-year experience of poison centers in the United States

This study was undertaken to evaluate trends and toxicity of pediatric methylphenidate exposures; 1993 to 1999 national poison center data were analyzed. There were 12,917 exposures, increasing from 927 in 1993 to 2,445 in 1999. The majority of children during the entire study period experienced no effect (60.3%) or minor effects (28.7%), with no fatalities. Most common reasons were unintentional general or therapeutic errors in children under 13 years and suicide attempt in adolescents. Adolescents were more likely to experience clinical toxicity, hospitalizations and more serious outcomes. The trend of increasing frequency of methylphenidate exposures reported to poison centers exactly parallels increasing therapeutic use.

Poison centers' experience with methylphenidate abuse in pre-teens and adolescents

OBJECTIVE

To evaluate trends and toxicity of methylphenidate abuse in pre-teens and adolescents reported to poison centers.

METHOD

The 1993-1999 American Association of Poison Control Centers Toxic Exposure Surveillance System was queried for methylphenidate abuse cases in children aged 10 through 19 years that were followed to known outcome. Main outcome measures included number of cases annually, toxicity, management site, and coded medical outcome.

RESULTS

Of 759 cases, 42.7% involved 10-through 14-year-olds. For the 530 (70.0%) cases involving methylphenidate only, the frequency increased sevenfold from 1993 to 1999. Of 570 patients (75.1%) managed in a health care facility, 398 were discharged from the emergency department and 172 were admitted. Symptoms occurred more commonly in exposures involving coingestants (84.3%) than in methylphenidate-only exposures (71.1%). The most common symptoms in adolescents with methylphenidate only were tachycardia (31.7%), agitation/irritability (25.7%), and hypertension (11.5%). Outcomes were no effect in 189 cases (24.9%) and mild, moderate, and severe in 318 (41.9%), 245 (32.3%), and 7 (0.9%) patients, respectively.

CONCLUSIONS

Poison center data demonstrate increasing frequency of methylphenidate abuse. While the majority of adolescents experienced clinical effects and were managed in a health care facility, outcomes were good, especially in cases involving methylphenidate only.

Adverse events associated with dietary supplements: an observational study

BACKGROUND

Adverse events associated with dietary supplements are difficult to monitor in the USA, because such products are not registered before sale, and there is little information about their content and safety.

METHODS

In 1998, 11 poison control centres in the USA recorded details of 2332 telephone calls about 1466 ingestions of dietary supplements, in 784 of which patients had symptoms. We used a multitiered review process (kappa 0.42) to select 489 cases for whom we were at least 50% certain that their negative events were associated with dietary supplements. We aimed to assess the effects of multiple ingredients and long-term use, and collated data for patterns of use and information resources.

FINDINGS

A third of events were of greater than mild severity. We noted both new and previously reported associations that included myocardial infarction, liver failure, bleeding, seizures, and death. Increased symptom severity was associated with use of several ingredients, long-term use, and age. Paediatric exposures were more often unintentional than were adult ingestions, and treatment of disease was the reason for supplement use in at least 28% of reports. Most products and ingredients were not identified in the information database (Poisindex) used by poison control centres, and specific adverse events were reported variably among five additional sources.

INTERPRETATION

Dietary supplements are associated with adverse events that include all levels of severity, organ systems, and age groups. Associations between adverse events and ingredients are difficult to verify if a product has more than one ingredient, and because of incomplete information systems. Research into hazards and risks of dietary supplements should be a priority.

Electrocardiographic changes associated with beta-blocker toxicity

STUDY OBJECTIVE

We sought to characterize the ECG changes associated with symptomatic beta-blocker overdose.

METHODS

The study population consisted of a prospective cohort of patients reporting to 2 regional poison centers with beta-blocker overdose. Each patient received an ECG on presentation and a structured follow-up. The inclusion criteria for symptomatic overdose included heart rate of less than 60 beats/min or systolic blood pressure of less than 90 mm Hg; symptoms consistent with decreased end-organ perfusion; therapeutic intervention with cardioactive medication; and corroboration by 2 of the authors that this was a clear-cut case of symptomatic beta-blocker overdose with cardiovascular toxicity. Exclusion criteria included cardioactive coingestants, age younger than 6 years, and no available ECG.

RESULTS

Of 167 patients, 13 were determined to have symptomatic exposures. First-degree heart block (>200 ms) was the most common ECG finding (10/12) and also had the greatest likelihood ratio (5.31) when comparing those with symptomatic exposures with those with asymptomatic exposures. Comparing the asymptomatic with the symptomatic groups, the mean PR interval was 167 ms (95% confidence interval [CI] 162 to 171 ms) versus 216 ms (95% CI 193 to 238 ms), the mean QRS interval was 89 ms (95% CI 87 to 91 ms) versus 112 ms (95% CI 92 to 132 ms), the mean QTc interval was 422 ms (95% CI 417 to 428) versus 462 ms (95% CI 434 to 490 ms), and the mean heart rate was 72 beats/min (95% CI 69 to 74 beats/min) versus 66 beats/min (95% CI 59 to 73 beats/min). Two cases of symptomatic acebutolol exposure appeared unique by demonstrating disproportionate prolongation of the QTc interval, an RaVR height of 3 mm or greater, and associated ventricular tachydysrhythmia.

CONCLUSION

The majority of clinically significant beta-blocker intoxications demonstrate negative dromotropic effects on ECG. Several ECG differences in acebutolol intoxication might reflect unique pathophysiologic processes relative to other beta-blockers.

Epidemiology and toxicity of pediatric guanfacine exposures

OBJECTIVE

To examine the epidemiology and toxicity of guanfacine exposures in children and adolescents reported to poison control centers.

METHODS

Guanfacine exposures reported to the American Association of Poison Control Centers Toxic Exposure Surveillance System from 1993 to 1999 in children and adolescents <19 years of age were analyzed.

RESULTS

There were 870 cases that met the inclusion criteria: 478 (54.9%) were children <6 years old, 304 (34.9%) were 6-12 years old, and 88 (10.1%) were adolescents 13-18 years old. The number of cases increased eight-fold over the 7-year period, with the largest increase in children <13 years of age. Analysis showed 29.7% of exposures were managed on site (non-healthcare facility) and 68.3% were managed in a healthcare facility. There were no symptoms in 546 (62.8%) children. In 324 symptomatic children, the most common symptoms were drowsiness/lethargy (76.8%), bradycardia (30.0%), and hypotension (25.8%). The majority of cases were acute (77.5%), 182 (20.9%) were acute-on-chronic, and 14 (1.6%) were chronic. Children aged 6-12 years represented the majority of the acute-on-chronic and chronic exposures with (n = 118). Overall, there were 195 (22.4%) exposures coded as minor, 121 (13.9%) as moderate, and 8 (0.9%) as major effects.

CONCLUSIONS

These data demonstrated a trend of increasing numbers of guanfacine exposures annually. Although the majority of children experienced minimal or no toxicity, serious toxicity can occur.