Unintentional cetirizine overdose causing anticholinergic syndrome.

The incidence of anticholinergic syndrome due to second generation antihistamines is infrequently reported. Largely due to their decreased affinity for central nervous system (CNS) receptors, second generation antihistamines are rarely associated with anticholinergic symptoms, though toxicity is still possible particularly when taken in excess. We report a case of a six year old boy who presented with agitation, hallucinations, fixed and dilated pupils, tachycardia, and hyperthermia consistent with anticholinergic toxicity several hours after accidental overdose of a second generation antihistamine, cetirizine. Early identification of this rare phenomenon is important not only for appropriate emergency management but also for avoidance of potentially invasive and unnecessary tests which may further increase patient morbidity.

Diphenhydramine exposure in dogs: 621 cases (2008-2013).

OBJECTIVE To characterize the signalment, dose response, and clinical signs of diphenhydramine toxicosis in dogs. DESIGN Retrospective case series. ANIMALS 621 dogs with diphenhydramine exposure. PROCEDURES The electronic medical record database for an animal poison control center was reviewed from January 2008 through December 2013 to identify dogs that had ingested or been injected with diphenhydramine. Information extracted from the records and evaluated included the signalment, clinical signs observed, and estimated exposure dose of diphenhydramine. Clinical signs were categorized as none, mild, moderate, and severe. RESULTS The mean ± SEM age of dogs was 3.6 ± 0.1 years (range, 0.1 to 16 years). Diphenhydramine exposure was by ingestion for 581 (93.6%) dogs and injection for 40 (6.4%) dogs. Only 146 (23.5%) dogs developed ≥ 1 clinical signs of toxicosis, the most common of which were associated with the nervous (lethargy, hyperactivity, agitation, hyperthermia, ataxia, tremors, and fasciculations) or cardiovascular (tachycardia) systems, and 3 dogs died. Although the presence and extent of clinical signs varied greatly among dogs, the exposure dose of diphenhydramine was positively associated with the severity of clinical signs in a dose-dependent manner regardless of the route of exposure (ingestion or injection). CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that dogs exposed to diphenhydramine developed clinical signs of toxicosis fairly infrequently, and those clinical signs were generally mild and primarily affected the neurologic and cardiovascular systems. Supportive treatment for diphenhydramine toxicosis should be administered on the basis of the clinical signs observed.

A pseudoencephalitis presentation of a pediatric non-intentional intoxication.

UNLABELLED: We report a case of a pseudo encephalitis presentation of pediatric intoxication - Case report - a 7 year-old girl was admitted to our pediatric emergency unit after she developed sudden agitation, visual and tactile hallucinations. She was febrile (38.3 °C). She had not experienced any recent head trauma, infection or toxic ingestion; she did not take any medication for ADD. Her physical exam revealed tachycardia, normal pupils, reflexes and normal plantar responses. Laboratory investigations (complete blood count, basic metabolic panel, plasma lactate level, ammonia level) produced normal results. Lumbar puncture and computed tomography of the brain were normal. A serum and urine drug screening (benzodiazepines, barbiturates, cocaine, cannabis, amphetamines, methadone, ethanol) was negative. An electroencephalogram, performed during an episode of hallucinations, was compatible with benzodiazepine intoxication. A larger toxic detection by liquid chromatography/diode array detector (LC-DAD) detected promethazine and its metabolites. Symptoms lasted 20 h and she finally said she drank syrup from an over-the-counter cough suppressant medication. Comments - Anticholinergic syndrome is not well recognized or evoked in children presenting hallucinations. Promethazine is still present in several over-the-counter medications, alone or in combination with acetaminophen, carbocisteine or opiates. CONCLUSION: Medications containing promethazine should not be prescribed in children. Such intoxication can mimic encephalitis.

Implications of diphenhydramine single-dose unintended ingestions in young children.

BACKGROUND: Diphenhydramine is frequently used in children, but the consequences of single unintended dose exposures in young children are unknown. METHODS: We evaluated 2000-2001 American Association of Poison Control Centers-Toxic Exposure Surveillance data on children exposed to diphenhydramine ingestions. RESULTS: Nine hundred twenty-six cases met the inclusion criteria; 49.1% were men, mean age was 29.7 +/- 13.0 months (range, 1-72 months). Approximately 85% of unintentional exposures occurred in 1- to 3-year-old children. The mean dose ingested was 6.4 +/- 6.1 mg/kg (median, 4.6 mg/kg). Thirty-two percent of patients were symptomatic: minor (29.4%), moderate (2.9%), and severe (0.11%). There was no relationship between dose and symptom severity. Diphenhydramine dose ingestion of 7.5 mg/kg or greater was not a predictor of severity (P = 0.47) CONCLUSIONS: The relationship between ingested dose and severity of symptoms was insignificant.

How much is too much? Oligosymptomatic presentation after 11.5 g of diphenhydramine.

We report the case of a 47-year-old male obese Caucasian patient presenting 2 hours after ingestion of 11.5 g of diphenhydramine. Despite this excessive overdose, he showed only a few hours of impaired consciousness and no further symptoms. A diphenhydramine plasma concentration of 15,352 nmol/L was measured 8 hours after the overdose ingestion. A heterogeneous CYP2D6 extensive metabolizer genotype excludes a pharmacokinetic explanation for this unusually oligosymptomatic presentation. However, the patient suffered from longstanding, refractory depression despite numerous treatment attempts with various drugs, pointing to the possibility of decreased pharmacodynamic responsiveness for therapeutic and toxic effects.

[Fatal suicidal intoxication with cetirizine in patient with anorexia--a case report]. / Samobójcze smiertelne zatrucie cetyryzyna u chorej leczonej z powodu jadlowstretu psychicznego--opis przypadku.

According to the best of our knowledge this is the first case of acute fatal intoxication with cetirizine published in medical literature. We have described the case of a 18-year-old female with the history of anorexia for 2 years, who was admitted to Clinic of Toxicology because of suicidal attempt with use of cetirizine. The laboratory results revealed metabolic acidosis with the pH 7.13; pO2 88 mm Hg; pCO2 36 mm Hg; HCO3 12.0 mmol/L; BE (-)17 mmol/L; SO2 100% and hypokalemia (K+ 3.1 mmol/L). On physical examination blood pressure was 70/40 mm Hg, heart rate was 36-40 beats/min. Convulsions were observed. After about two hours of intensive treatment there was a cardiac arrest in the form of ventricular fibrillation. The resuscitation procedures which lasted for over 2.5 hours were ineffective. The high dose (270 mg) of cetirizine as well as anorexia and hypokalemia could have been the cause of the unique character of the symptoms in this case. Further investigations should be carried out to confirm the safety of cetirizine in the conditions of massive intoxication and with coexistence of other risk factors.

Case of polymorphic ventricular tachycardia in diphenhydramine poisoning.

This is the first reported case of torsades de pointes attributable to diphenhydramine, a drug with weak I(Kr) effects. A 26-year-old, healthy man was admitted to intensive care after a diphenhydramine overdose. Results of physical examination, ECG, and electrolytes were normal at admission. Despite supportive care, he developed typical, sustained, torsades de pointes with a markedly prolonged QT interval requiring cardioversion. Drugs with weak I(Kr)-blocking effects may cause lethal proarrhythmia in susceptible individuals when delivered in high concentrations. This case illustrates the variation in repolarization reserve that exists in a free-standing population.

High-dose loratadine exposure in a six-year-old child.

Loratadine is a long-acting antihistamine indicated for the treatment of seasonal allergic rhinitis and chronic idiopathic urticaria in patients 6 years of age and older. The literature contains little information on high-dose loratadine exposures; as a consequence, poison centers are unsure of the loratadine dose that can be managed with observation and the dose that requires treatment. We report an intentional ingestion of 300 mg loratadine by a 6-y-old child that resulted in minor elevation of blood pressure and heart rate when managed with supportive care only. Further studies and case series are needed before a minimum toxic dose can be established.