Clonidine poisoning in young children

Clinical Effects of Pediatric Clonidine Exposure: A Retrospective Cohort Study at a Single Tertiary Care Center

BACKGROUND

Pediatric clonidine ingestions frequently result in emergency department visits and admission for cardiac monitoring. Detailed information on the clinical course and specifically time of vital sign abnormalities of these patients is lacking.

OBJECTIVE

The objective of this study was to provide descriptive analysis of the rates and times to vital sign abnormalities, treatment, disposition, and outcomes in a single-center cohort of pediatric patients with report of clonidine poisoning.

METHODS

We performed a retrospective cohort study of patients younger than 21 years who presented to a large, urban, tertiary care center with a report of single substance clonidine exposure between January 2004 and November 2017. Patients were dichotomized into younger (≤9 years or younger) and older (10-21 years) groups based on the expected physiologic and psychologic differences between older and younger children.

RESULTS

Eighty-eight patients met our inclusion criteria. Younger patients (≤9 years or younger; n = 47) were more likely to be exposed to someone else's medication (53%) and older patients (10-21 years; n = 41) overwhelmingly (85%) were exposed to their own medication. Thirty-nine (45%) became bradycardic, 27 (32%) became bradypneic, and 38 (44%) became hypotensive. Eighty percent of patients had depressed mental status. Thirty-three (38%) patients received at least one dose of naloxone (median 0.07 mg/kg; interquartile range 0.03-0.11 mg/kg). Of those who received naloxone, 50% had a documented clinical response.

CONCLUSIONS

In this study of patients at a pediatric tertiary referral center, pediatric patients with report of clonidine exposures were likely to exhibit altered mental status and frequently develop vital sign abnormalities. Naloxone exhibited some effectiveness; given its wide safety margin, high-dose naloxone should be used in critically poisoned non-opioid-dependent patients. Because adolescents are much more likely to ingest their own clonidine medication, counseling with parents and other caregivers regarding safe medication storage is paramount.

Outcomes following clonidine ingestions in children: an analysis of poison control center data

Background

This paper sought to characterize pediatric clonidine ingestions, report trends in incidence, and evaluate outcomes using the Florida Poison Center’s data over a period of 15 years, from 2002 to 2016.

Results

There were 3444 total exposures. Forty percent of the cohort was female. The median age was 5 years. The age distribution changed over time to a higher proportion of teenagers exposed (p < 0.0001). From 2002 to 2016, exposures increased from 182 to 378 with a rise in incidence from 4.8 to 9.1 per 100,000 children. Acute on chronic exposures increased from 29.3% to 42.2% (p < 0.0001). Female intentional ingestions increased from 52 to 70% (p < 0.0001). Twenty-four percent were managed at home, 34% were discharged from the emergency department, 8% were admitted to the floor, and 25% were admitted to the intensive care unit (ICU). Major medical outcomes were associated with older age (p = 0.0043, 95% CI 0.0015 to 0.0080) and higher clonidine dose (p < 0.0001, 95% CI 0.0347 to 0.0600). Older children were more likely to ingest a larger dose of clonidine (p < 0.001, 95% CI 0.0531 to 0.0734), while younger children were more likely to be admitted to the ICU (p < 0.001, 95% CI − 0.0092 to − 0.0033). Males were more likely to have acute on chronic ingestions (p < 0.001, 95% CI − 0.1639 to − 0.0982); females were significantly more likely to be admitted to the ICU (p < 0.0001, 95% CI 0.0380 to 0.0969).

Conclusions

Our analysis shows an increase in the incidence in pediatric clonidine exposures over time despite adjustment for population growth.

Prospective multicentre randomised, double-blind, equivalence study comparing clonidine and midazolam as intravenous sedative agents in critically ill children: the SLEEPS (Safety profiLe, Efficacy and Equivalence in Paediatric intensive care Sedation) study

BACKGROUND

Children in paediatric intensive care units (PICUs) require analgesia and sedation but both undersedation and oversedation can be harmful.

OBJECTIVE

Evaluation of intravenous (i.v.) clonidine as an alternative to i.v. midazolam.

DESIGN

Multicentre, double-blind, randomised equivalence trial.

SETTING

Ten UK PICUs.

PARTICIPANTS

Children (30 days to 15 years inclusive) weighing ≤ 50 kg, expected to require ventilation on PICU for > 12 hours.

INTERVENTIONS

Clonidine (3 µg/kg loading then 0-3 µg/kg/hour) versus midazolam (200 µg/kg loading then 0-200 µg/kg/hour). Maintenance infusion rates adjusted according to behavioural assessment (COMFORT score). Both groups also received morphine.

MAIN OUTCOME MEASURES

Primary end point Adequate sedation defined by COMFORT score of 17-26 for ≥ 80% of the time with a ± 0.15 margin of equivalence. Secondary end points Percentage of time spent adequately sedated, increase in sedation/analgesia, recovery after sedation, side effects and safety data.

RESULTS

The study planned to recruit 1000 children. In total, 129 children were randomised, of whom 120 (93%) contributed data for the primary outcome. The proportion of children who were adequately sedated for ≥ 80% of the time was 21 of 61 (34.4%) - clonidine, and 18 of 59 (30.5%) - midazolam. The difference in proportions for clonidine-midazolam was 0.04 [95% confidence interval (CI) -0.13 to 0.21], and, with the 95% CI including values outside the range of equivalence (-0.15 to 0.15), equivalence was not demonstrated; however, the study was underpowered. Non-inferiority of clonidine to midazolam was established, with the only values outside the equivalence range favouring clonidine. Times to reach maximum sedation and analgesia were comparable hazard ratios: 0.99 (95% CI 0.53 to 1.82) and 1.18 (95% CI 0.49 to 2.86), respectively. Percentage time spent adequately sedated was similar [medians clonidine 73.8% vs. midazolam 72.8%: difference in medians 0.66 (95% CI -5.25 to 7.24)]. Treatment failure was 12 of 64 (18.8%) on clonidine and 7 of 61 (11.5%) on midazolam [risk ratio (RR) 1.63, 95% CI 0.69 to 3.88]. Proportions with withdrawal symptoms [28/60 (46.7%) vs. 30/58 (52.6%)] were similar (RR 0.89, 95% CI 0.62 to 1.28), but a greater proportion required clinical intervention in those receiving midazolam [11/60 (18.3%) vs. 16/58 (27.6%) (RR 0.66, 95% CI 0.34 to 1.31)]. Post treatment, one child on clonidine experienced mild rebound hypertension, not requiring intervention. A higher incidence of inotropic support during the first 12 hours was required for those on clonidine [clonidine 5/45 (11.1%) vs. midazolam 3/52 (5.8%)] (RR 1.93 95% CI 0.49 to 7.61).

CONCLUSIONS

Clonidine is an alternative to midazolam. Our trial-based economic evaluation suggests that clonidine is likely to be a cost-effective sedative agent in the PICU in comparison with midazolam (probability of cost-effectiveness exceeds 50%). Rebound hypertension did not appear to be a significant problem with clonidine but, owing to its effects on heart rate, specific cardiovascular attention needs to be taken during the loading and early infusion phase. Neither drug in combination with morphine provided ideal sedation, suggesting that in unparalysed patients a third background agent is necessary. The disappointing recruitment rates reflect a reluctance of parents to provide consent when established on a sedation regimen, and reluctance of clinicians to allow sedation to be studied in unstable critically ill children. Future studies will require less exacting protocols allowing enhanced recruitment.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN02639863.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 18, No. 71. See the NIHR Journals Library website for further project information.

[Clonidine poisoning in a child: a case report]

Clonidine poisoning's clinical feature is well documented in the medical literature, but the minimal toxic dose has not yet been established. The effectiveness of naloxone is also controversial. The authors describe a clonidine overdose in a 9-year-old boy (25 kg) during a growth hormone test: he received tenfold the prescribed clonidine dose (0.23 mg instead of 0.023 mg) with 6.2 mg betaxolol. About 40 min later, he became drowsy and then complained of low blood pressure, bradycardia, and myosis. By maintaining the Trendelenburg position, administering fluids as well as salbutamol and naloxone (three doses of 0.2 mg were required), he recovered and was discharged from the hospital on day 2. The minimal clonidine toxic dose, the clinical picture, and the effectiveness of naloxone administration are discussed in this paper.

Toxicity of antihypertensives in unintentional poisoning of young children

BACKGROUND

Knowledge is limited about the toxicity of unintentional exposure to antihypertensives in young children (0-6 years of age).

OBJECTIVE

Our aim was to research symptoms and poisoning severity in unintentional poisonings in this group of age and determine adequate poisoning management.

METHODS

We performed a 10-year retrospective, explorative analysis of the Mainz Poison Center/Germany database with regard to circumstances of poison exposure, dosage, symptoms, and treatment. To be able to relate drug exposure with reported symptoms, analyses were restricted to single drug exposures. Written follow-up information was obtained in about 50% of all cases.

RESULTS

A total of 1489 cases were analyzed, of which 957 were single drug exposures with 421 exposures to beta-blocking agents, 364 to inhibitors of the renin-angiotensin system, 122 to calcium channel blockers, and 50 to antiadrenergic drugs. No severe (Poisoning Severity Score [PSS]=3) or fatal poisonings (PSS=4) were reported and, with the exception of atenolol, propranolol, irbesartan, isradipin, clonidine, and moxonidine, no poisonings with a PSS>1. We did not find a significant relationship between dosage, release formulation and symptoms, or PSS. All patients fully recovered without specific treatment.

CONCLUSIONS

In young children with unintentional, single drug exposure to the most popular antihypertensive medication (i.e., metoprolol, bisoprolol, ramipril, enalapril, lisinopril, captopril, candesartan, valsartan, amlodipine, and verapamil), only mild symptoms occurred, and hospital evaluation is not a must. However, children with recent exposure to clonidine or moxonidine should be evaluated at a hospital due to an increased likelihood of poisonings of at least moderate severity.

Overdose of drugs for attention-deficit hyperactivity disorder: clinical presentation, mechanisms of toxicity, and management

The prevalence of attention-deficit hyperactivity disorder (ADHD) in the USA is estimated at approximately 4-9% in children and 4% in adults. It is estimated that prescriptions for ADHD medications are written for more than 2.7 million children per year. In 2010, US poison centers reported 17,000 human exposures to ADHD medications, with 80% occurring in children <19 years old and 20% in adults. The drugs used for the treatment of ADHD are diverse but can be roughly separated into two groups: the stimulants such as amphetamine, methylphenidate, and modafinil; and the non-stimulants such as atomoxetine, guanfacine, and clonidine. This review focuses on mechanisms of toxicity after overdose with ADHD medications, clinical effects from overdose, and management. Amphetamine, dextroamphetamine, and methylphenidate act as substrates for the cellular monoamine transporter, especially the dopamine transporter (DAT) and less so the norepinephrine (NET) and serotonin transporter. The mechanism of toxicity is primarily related to excessive extracellular dopamine, norepinephrine, and serotonin. The primary clinical syndrome involves prominent neurological and cardiovascular effects, but secondary complications can involve renal, muscle, pulmonary, and gastrointestinal (GI) effects. In overdose, the patient may present with mydriasis, tremor, agitation, hyperreflexia, combative behavior, confusion, hallucinations, delirium, anxiety, paranoia, movement disorders, and seizures. The management of amphetamine, dextroamphetamine, and methylphenidate overdose is largely supportive, with a focus on interruption of the sympathomimetic syndrome with judicious use of benzodiazepines. In cases where agitation, delirium, and movement disorders are unresponsive to benzodiazepines, second-line therapies include antipsychotics such as ziprasidone or haloperidol, central alpha-adrenoreceptor agonists such as dexmedetomidine, or propofol. Modafinil is not US FDA approved for treatment of ADHD; however, it has been shown to improve ADHD signs and symptoms and has been used as an off-label pharmaceutical for this diagnosis in both adults and children. The mechanism of action of modafinil is complex and not fully understood. It is known to cause an increase in extracellular concentrations of dopamine, norepinephrine, and serotonin in the neocortex. Overdose with modafinil is generally of moderate severity, with reported ingestions of doses up to 8 g. The most common neurological effects include increased anxiety, agitation, headache, dizziness, insomnia, tremors, and dystonia. The management of modafinil overdose is largely supportive, with a focus on sedation, and control of dyskinesias and blood pressure. Atomoxetine is a selective presynaptic norepinephrine transporter inhibitor. The clinical presentation after overdose with atomoxetine has generally been mild. The primary effects have been drowsiness, agitation, hyperactivity, GI upset, tremor, hyperreflexia, tachycardia hypertension, and seizure. The management of atomoxetine overdose is largely supportive, with a focus on sedation, and control of dyskinesias and seizures. Clonidine is a synthetic imidazole derivative with both central and peripheral alpha-adrenergic agonist actions. The primary clinical syndrome involves prominent neurological and cardiovascular effects, with the most commonly reported features of depressed sensorium, bradycardia, and hypotension. While clonidine is an anti-hypertensive medication, a paradoxical hypertension may occur early with overdose. The clinical syndrome after overdose of guanfacine may be mixed depending on central or peripheral alpha-adrenoreceptor effects. Initial clinical effects may be drowsiness, lethargy, dry mouth, and diaphoresis. Cardiovascular effects may depend on time post-ingestion and may present as hypotension or hypertension. The management of guanfacine overdose is largely supportive, with a focus on support of blood pressure. Overdose with ADHD medications can produce major morbidity, with many cases requiring intensive care medicine and prolonged hospital stays. However, fatalities are rare with appropriate care.

The poisoned child in the pediatric intensive care unit

Acutely poisoned children remain a common problem facing pediatricians working in acute care medicine in the United States and worldwide. The management of such children continues to be challenging, and their care has evolved throughout the years. The concept of gastric decontamination in acute poisoning has significantly changed over the past 10 years, and many of the previously used techniques have been abandoned or fallen out of favor for lack of evidence to their benefit or unacceptable serious risks and side effects. Supportive care continues to be the cornerstone in managing most poisoned children. Only a few patients benefit from antidotes or specific interventions.

Zentralnervöse Atemdepression als Komplikation der Behandlung des kongenitalen Glaukoms mit Brominidin-Augentropfen

We report the case of a premature newborn (gestational age 33 weeks) with congenital glaucoma. After a trabeculotomy high intraocular pressure persisted, leading to adjuvant treatment with timolol and--when the infant was 3 weeks old--with brimonidine. After the first application of topical brimonidine the infant developed such severe apnoeic spells that intubation and temporary ventilation were necessary. A review of the literature reveals that when used in young infants brimonidine eye drops can potentially have toxic effects on the central nervous system (e.g. respiratory depression). The use of topical brimonidine is therefore not advised in this age group.

TESS-based dose–response using pediatric clonidine exposures

OBJECTIVE

The toxic and lethal doses of clonidine in children are unclear. This study was designed to determine whether data from the American Association of Poison Control Centers Toxic Exposure Surveillance System (TESS) could be utilized to determine a dose-response relationship for pediatric clonidine exposure.

METHODS

3,458 single-substance clonidine exposures in children <6 years of age reported to TESS from January 2000 through December 2003 were examined. Dose ingested, age, and medical outcome were available for 1550 cases. Respiratory arrest cases (n = 8) were classified as the most severe of the medical outcome categories (Arrest, Major, Moderate, Mild, and No effect). Exposures reported as a "taste or lick" (n = 51) were included as a dose of 1/10 of the dosage form involved. Dose ranged from 0.4 to 1980 (median 13) microg/kg. Weight was imputed based on a quadratic estimate of weight for age. Dose certainty was coded as exact (26% of cases) or not exact (74%). Medical outcome (response) was examined via logistic regression using SAS JMP (release 5.1).

RESULTS

The logistic model describing medical outcome (P < 0.0001) included Log dose/kg (P = 0.0000) and Certainty (P = 0.045).

CONCLUSION

TESS data can provide the basis for a statistically sound description of dose-response for pediatric clonidine poisoning exposures.

Deadly ingestions

More than 50% of the toxic-exposure calls to US poison centers involve children. Although most of these exposures are nontoxic, there are several products and medications that are widely available to the pediatric population that can lead to severe toxicity or even death. With some of these medications, death or severe symptoms can occur with the ingestion of only a small amount. It is important that the clinician be familiar with presenting signs and symptoms of potentially toxic ingestions and is able to initiate a therapeutic and life-saving intervention. This article reviews some of the deadlier ingestions that children may be exposed to.

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.

Deadly pediatric poisons: nine common agents that kill at low doses

More than 97% of pediatric exposures reported to the AAPCC in 2001 had either no effect or mild clinical effects. Despite the large number of exposures, only 26 of the 1074 reported fatalities occurred in children younger than age 6. These findings reflect the fact that, in contrast to adolescent or adult ingestions, pediatric ingestions are unintentional events secondary to development of exploration behaviors and the tendency to place objects in the mouth. Ingested substances typically are nontoxic or ingested in such small quantities that toxicity would not be expected. As a result, it commonly is believed that ingestion of one or two tablets by a toddler is a benign act and not expected to produce any consequential toxicity. Select agents have the potential to produce profound toxicity and death, however, despite the ingestion of only one or two tablets or sips. Although proven antidotes are a valuable resource, their value is diminished if risk after ingestion is not adequately appreciated and assessed. Future research into low-dose, high-risk exposures should be directed toward further clarification of risk, improvements in overall management strategies,and, perhaps most importantly, prevention of toxic exposure through parental education and appropriate safety legislation.

Clonidine poisoning in children: a recent experience

OBJECTIVES

To identify cases of clonidine poisoning presenting to a tertiary paediatric hospital and to investigate trends in presentation, outcome and prevention. Furthermore, any public health implications of the use of clonidine in children are to be explored.

METHODS

Cases of clonidine poisoning presenting to Royal Children's Hospital were reviewed over the period from 1997 to 2001 (inclusive), with significant data obtained from coded medical records.

RESULTS

Twenty-four cases of clonidine poisoning were identified over the 5-year period. Nine patients ingested their own medication, which was prescribed for attention-deficit hyperactivity disorder. Clonidine was prescribed for a child in 16 cases (67%). Impaired conscious state and bradycardia were the most common presenting features. Activated charcoal was given in 14 cases and volume expansion in six. There were 12 children (50%) who required admission to intensive care for monitoring, including three who received mechanical ventilation. The average length of stay was 25.7 h with no long-term complications.

CONCLUSIONS

This is the largest series of clonidine poisoning in children recorded in Australia, with morbidity considerable. Emphasis needs to be placed on educating parents of clonidine's dangers in overdose to their own children as well as others.

Retrospective review of Tizanidine (Zanaflex) overdose

BACKGROUND

Tizanidine is a centrally acting muscle relaxant with a novel mechanism of action and structurally related to clonidine. There are no large case series of tizanidine exposure.

METHODS

Retrospective review of all ingestions involving tizanidine reported to a poison control center from January 2000 through February 2003. Exclusion criteria were polydrug ingestion, no follow-up or lost to follow-up.

RESULTS

There were 121 cases of which 45 patients met entrance criteria. Mean age was 32 years (range 1 to 80). Thirty-seven patients were evaluated in a health care facility of which 27 were admitted for medical care. Clinical effects included lethargy (n = 38), bradycardia (n = 14), hypotension (n = 8), agitation (n = 7), confusion (n = 5), vomiting (n = 3), and coma (n = 2). Mean dose ingested by history was 72 mg (S.D. + 86). The lowest dose associated with hypotension was 28mg, which occurred in a 63-year-old female with a BP of 88/52 and a HR of 54. The lowest dose associated with coma was between 60 mg and 120 mg, which occurred in a 30-year-old female with a HR of 30 and BP of 81/48. There were 6 patients < 6 yrs. The lowest dose with bradycardia and drowsiness in a small child was 16 mg in a 2 YO (weight unknown). All other cases in children < 6 yrs involved ingestion of a single tablet (2 or 4 mg) with only mild drowsiness reported. Therapy in this series was primarily supportive and included pressors in 3 cases and intubation in 3 cases. Naloxone was administered to 7 patients. There was no response to naloxone in 5 patients, poor documentation of response in one, and arousal in one patient. All patients recovered without residual complications.

CONCLUSION

Clinical manifestations of tizanidine overdose include alterations of mental status, bradycardia, and hypotension. In this series, outcome was good with supportive therapy.

Are one or two dangerous? Clonidine and topical imidazolines exposure in toddlers

Clonidine and the imidazolines, commonly found in topical ophthalmic and nasal decongestants, are chemically related drugs that have been responsible for many pediatric poisonings. These medications can cause significant morbidity in small doses. A review of the available literature reveals that young children have exhibited severe signs and symptoms after ingesting as little as one to two clonidine tablets or 2.5 ml of a topical imidazoline product. Central nervous system depression, respiratory depression, and cardiovascular instability are the most common features of poisoning. Signs and symptoms develop rapidly, within 4-6 h. Care is supportive. Death is rare, but many poisoned patients require monitoring in an intensive care setting.

Management of toxic exposure in children

Millions of children ingest household products and medications yearly. The continuous proliferation of new products and pharmaceutic agents makes it difficult for physicians to maintain a current command of toxicologic information. Multiple sources, including poison control centers, can provide information; however, EPs must be familiar with several agents that are either significant for their frequency or for their disproportionate potential for morbidity and mortality in pediatric patients. With this select group of intoxicants, physicians must anticipate cardiovascular and pulmonary instability and rapid changes in central nervous system functioning. Appropriate supportive care requires monitoring of the following: vital signs, level of consciousness, airway control, ventilation and circulatory support, body temperature, urine output, and acid base balance. Once these concerns are addressed, prevention of further absorption, enhancing a product's elimination, and treatment with specific antidotes may enhance supportive care. Care is also likely to be enhanced if the EP recognizes the inherent differences (medically and socially) between adults and children of various ages. Definitive emergency care is completed only after the provision of a developmentally oriented preventive strategy.

Clonidine toxicity revisited

The incidence of clonidine overdose is increasing, yet there is a paucity of new information regarding treatment options for clonidine toxicity. Reported treatment approaches vary widely, demonstrating the lack of science on which current treatment is based. Available research needs to be reassessed. Neurotransmitters, receptors, endogenous opioids, and baseline sympathetic tone determine the clinical response to clonidine as well as the potential response to drug therapy following clonidine overdose. This article reviews aspects of clonidine toxicity that need to be further investigated. Multicenter research trials will be required to evaluate new treatment options.

Pediatric toxicologic concerns

Pediatric poisonings account for significant morbidity in the United States each year. Clinicians must keep current with advances in toxicology to be familiar with the latest recommended treatment regimens and antidotes. They also must be familiar in identifying toxidromes and important physical examination findings. Having these skills can enable the clinician to determine who is at risk for significant morbidity or mortality and to provide the appropriate medical care.

Severe intoxication from xylazine inhalation

We present the first documented case of overdose from xylazine inhalation. The patient developed findings consistent with alpha 2 adrenergic agonist toxicity, eg coma, miosis, apnea, bradycardia, hypothermia, and dry mouth 2 hours after exposure. Standard dose naloxone did not reverse these effects. The patient fully recovered after appropriate supportive measures. A review of prior reports of xylazine exposure is provided.

A 1000-fold overdose of clonidine caused by a compounding error in a 5-year-old child with attention-deficit/hyperactivity disorder

A 5-year-old child who weighed 17.5 kg received 50 mg of clonidine. The amount ingested was confirmed by analysis of the suspension administered (clonidine HCl 9.78 mg/mL). To our knowledge, this represents the largest ingestion in a child and the largest ingestion on a milligram per kilogram basis in the medical literature. The child's initial presentation included hyperventilation, an unusual feature of clonidine toxicity. The child was discharged without sequela 42 hours after admission. A serum concentration of clonidine 17 hours postingestion was 64 ng/mL, the highest reported to date in a pediatric patient. The intoxication was traced to a pharmacy compounding error in which milligrams were substituted for micrograms. Increased prescribing of clonidine in young children coupled with the requirement to compound clonidine in a suspension and the narrow therapeutic index suggests that the frequency of severe ingestions in children will increase in the future.

Ophthalmic drops causing coma in an infant

A 1-month-old infant with Peters anomaly had recurrent episodes of unresponsiveness, hypotension, hypotonia, hypothermia, and bradycardia. An extensive medical evaluation determined these episodes to be caused by brimonidine, an anti-glaucoma agent. There is the potential for serious toxic effects from the systemic absorption of topically applied ophthalmic agents in children.

Hypotension following the initiation of tizanidine in a patient treated with an angiotensin converting enzyme inhibitor for chronic hypertension

Centrally acting alpha-2 adrenergic agonists are one of several pharmacologic agents used in the treatment of spasticity related to disorders of the central nervous system. In addition to their effects on spasticity, certain adverse cardiorespiratory effects have been reported. Adults chronically treated with angiotensin converting enzyme inhibitors may have a limited ability to respond to hypotension when the sympathetic response is simultaneously blocked. The authors present a 10-year-old boy chronically treated with lisinopril, an angiotensin converting enzyme inhibitor, to control hypertension who developed hypotension following the addition of tizanidine, an alpha-2 agonist, for the treatment of spasticity. The possible interaction of tizanidine and other antihypertensive agents should be kept in mind when prescribing therapy to treat either hypertension or spasticity in such patients.

Drug Poisoning and Overdose for the Health Professional: Review of Select Over-the-Counter (OTC) and Prescription Medications

Exposure to over-the-counter and prescription medications can pose significant therapeutic and health hazards to patients, and present health care professionals with scenarios that require proper assessment and treatment. Knowing when an exposure to or overdose of a drug requires emergency medical attention is equally as important as to knowing when such assistance is not necessary—that simple treatment measures performed at home will suffice. This current discussion is intended to highlight select principles and clinical information pertaining to common drug exposures and overdoses, but not replace the full spectrum of information that would be available to health care professionals (and the lay public) by contacting their nearest poison control center. Many of the basic principles and concerns that are encountered with exposures to chemicals (i.e., route of exposure, patient medical history, quantity of the substance involved, elapsed time since the initial exposure, etc.) apply equally well to drug exposures. Likewise, evaluating each of these variables will determine which type of treatment approaches are, and are not, considered in situations of drug (or chemical) exposure and overdose.

Case study: accidental clonidine patch overdose in attention-deficit/hyperactivity disorder patients

The safety and efficacy of the clonidine patch are contingent on the integrity of the transdermal system and the condition of the dermal surface to which it is applied. This article presents the first 2 case reports in the literature of unintentional overdose in pediatric patients with attention-deficit/hyperactivity disorder treated with transdermal clonidine. Appropriate precautions and patient education can help limit toxicity from the clonidine patch in children and adolescents.

Clonidine overdose in childhood: implications of increased prescribing

OBJECTIVE

To highlight the increase in the number of cases of clonidine overdose admitted to a specialist paediatric hospital, with particular reference to the clinical features, clinical course and circumstances surrounding the incident.

METHODS

Cases of clonidine overdose were identified by review of the emergency department attendance register, the intensive care unit database and inpatient statistics collection. Case notes were reviewed to determine the clinical features, history and clinical course in each case.

RESULTS

Fifteen patients experienced 16 overdoses during the period 1990-97 inclusive. Only one case occurred before 1994. Depressed level of consciousness and bradycardia were the most common clinical manifestations, and were observed in 75 and 88% of cases respectively. There were no fatalities. Five patients received naloxone. Other treatment modalities included gastrointestinal decontamination, atropine, ventilation and inotropic support. Fourteen cases occurred in association with medication prescribed for attention-deficit hyperactivity disorder (ADHD).

CONCLUSION

Clonidine overdose is a potentially serious condition, often requiring intensive care management. Our experience suggests that it is a growing problem, related in part to its increased use in the treatment of ADHD. Preventive strategies, including raising the level of awareness of risks, changes to packaging and appropriate selection of patients for treatment, need consideration if further overdoses are to be prevented.

A 9-month-old with bradycardia and periodic apnea

The patient was discharged approximately 36 hours after admission to the emergency department. At that time she was awake and alert and responding appropriately to her surroundings. Her vital signs were within normal limits. It took approximately 2 weeks to receive the baby's clonidine level, which was 11.0 ng/mL; the therapeutic level is between 0.5 to 4.5 ng/mL. We came to the conclusion that the babysitter's clonidine patch had accidentally fallen into the playpen, where the baby subsequently sucked on it. To this day, the babysitter denies any involvement. Situations such as this confront emergency nurses every day, and questions arise regarding intent. In this case, the physician interviewed the babysitter and believed that the overdose was unintentional. Once again we are reminded of the fragility of life, the importance of capable, cautious caregivers, and just how easily accidents can happen. What a happy outcome this turned out to be after what appeared to be such a grave medical emergency on presentation!

Clonidine poisoning in Jefferson County, Alabama

STUDY OBJECTIVE

To describe the epidemiology of clonidine-related hospitalization in children, to evaluate the efficacy of naloxone, and to review the clinical effects of clonidine toxicity.

METHODS

This was a retrospective analysis in an urban teaching pediatric emergency department with an annual census of 55,000 involving 80 children younger than 6 years who were admitted for clonidine ingestion during a 6-year period.

RESULTS

Clonidine commonly belonged to the patient's grand-mother (54%). Black children were twice as likely to be hospitalized for clonidine ingestion than white children compared with children hospitalized for any injury. Average time to onset of symptoms was 35 minutes. Decreased level of consciousness was the most common presenting symptom (96%). Mean ED vital signs were systolic blood pressure, 102 mm Hg; pulse, 98; respirations, 25 (six patients intubated); and temperature, 36.6 degrees C, Naloxone was administered to 49% of patients, 84% of whom demonstrated no response.

CONCLUSION

Clonidine ingestion is endemic in our area. Serious clinical effects mandate that all children with clonidine ingestion be triaged to a health care facility. Naloxone as an antidote for clonidine remains controversial.

A comprehensive review of naloxone for the emergency physician

Naloxone has enjoyed long-standing success as a safe and effective opioid antagonist and has been invaluable in defining the role of endogenous opioid pathways in the response to pathological states such as sepsis and hypovolemia. We look forward to exciting research to further elucidate these pathways and to improve outcome by modulating the patient's physiological response to these stresses.

Update on Antidotal Therapy

Antidotal therapy is useful for only a meager number of poisonous agents in which reversal of the effects of the toxin, or treatment of the toxin-induced pathophysiologic derangements, is possible. This review of selected antidotes is meant to acquaint the reader with some of the new and/or controversial uses for a few of our older agents, to introduce two new agents recently marketed, and to refresh information on antidotes not often used.

Update in medical toxicology

This article examines some current issues in toxicologic care. First there is a review of the scope of pediatric poisonings and some aspects of initial management. Then there is a discussion of the decision-making process required to properly use gastric decontamination in the management of poisonings. Each of the common methods available--emesis, gastric lavage, activated charcoal, catharsis, and whole bowel irrigation--is discussed. Finally, several new and old antidotes are reviewed, namely naloxone, glucagon, bicarbonate, dimercaptosuccinic acid, digoxin-specific fab fragments, and flumazenil.

Difficult diagnoses in toxicology. Poisons not detected by the comprehensive drug screen

The comprehensive drug screen has serious limitations when used as the sole study for diagnosing intoxication. A careful history and physical examination in the poisoned patient can provide important clues that point to possible toxins. Ancillary studies help differentiate the most likely poison and guide treatment. Fortunately, most poison victims do well with supportive care alone. However, the clinician should be aware of agents that can cause significant harm to patients if not detected and treated quickly. Iron and carbon monoxide are good examples of lethal agents that need a high index of clinical suspicion for early recognition and require specific therapy to ensure a good outcome. Patients who overdose with clonidine, calcium-channel blockers, beta-adrenergic blockers, or albuterol must be managed expectantly and according to their clinical presentation because rapid laboratory verification is not available for these poisons. In all situations, the clinician must integrate information from history, physical examination, and laboratory to render the best care.