Rhabdomyolysis: a rare adverse effect of diphenhydramine overdose

Delayed-Onset olanzapine-induced rhabdomyolysis

Olanzapine is a commonly used and effective second-generation antipsychotic agent used for the control of paranoia and agitation in schizophrenia and bipolar disorder as well as in the behavioural and psychological symptoms of dementia. Serious side effects of treatment are uncommon but spontaneous rhabdomyolysis represents a rare complication. We describe here a patient treated with a stable dose of olanzapine for more than 8 years who developed acute severe rhabdomyolysis without an identifiable trigger and without features suggestive of neuroleptic malignant syndrome. The rhabdomyolysis was atypical in its delayed onset and severity with a creatine kinase level of 345 125 U/L, the highest level reported in the available literature. We also describe the clinical manifestations of delayed-onset olanzapine-induced rhabdomyolysis and its differentiation from neuroleptic malignancy syndrome, and we highlight key aspects of management to prevent or minimise further complications such as acute kidney injury.

Clinical and patient characteristics associated with severe outcome in diphenhydramine toxicity

BACKGROUND

Diphenhydramine is frequently misused and ingested recreationally for its antihistaminergic and antimuscarinic effects and is often involved in both serious and fatal poisonings, either in isolation or in combination with other xenobiotics.

OBJECTIVE

This analysis sought to determine which patient and encounter characteristics were associated with severe outcome after diphenhydramine overdose.

METHODS

This is an analysis of the multi-center ToxIC registry (2010-2016). Descriptive analysis of all cases with diphenhydramine listed as the "primary agent" contributing to toxicity were included. Analysis sought to determine which patient and encounter characteristics were associated with severe outcome, defined as occurrence of seizure, ventricular dysrhythmia, or intubation. To determine which patient and encounter characteristics were individually associated with severe outcome, we performed chi-square tests. Fisher's exact tests were used in the case of sparse data. We also performed multivariable logistic regression to further determine independent risk factors for severe outcome in diphenhydramine overdose.

RESULTS

Eight hundred and sixty-three cases remained after exclusion with 15.6% (n = 135) of all patients having one or more severe outcome. The most common severe outcome was seizures which occurred in 98 (11.6%) of all ingestions. Females comprised 59.1% (n = 510) of all ingestions. Most ingestions were intentional (86.0%, n = 742) with the most common known reason for an intentional ingestion being self-harm, accounting for 37.5% (n = 324) of all ingestions. Self-harm ingestions and ingestions in males were more commonly associated with intubation. When examining outcomes by age, there were no significant differences overall or in any individual outcome except intubation in which children 0-12 were less likely to be intubated as compared to teens and adults. Signs and symptoms most strongly associated with a severe outcome included acidemia (pH < 7.2), QRS prolongation (QRS > 120 ms), and elevated anion gap (AG > 20).

DISCUSSION

Acidemia, QRS prolongation, and elevated anion gap are associated with severe outcomes in diphenhydramine toxicity. Further research is warranted to determine their predictive characteristics.

QT interval prolongation and rhabdomyolysis associated with diphenhydramine toxicity: a case report

Diphenhydramine is a widely available, over-the-counter medication used for allergies and as a sleeping aid. When used in prescription doses, it is generally safe.

Overdose of the medication has been associated with dangerous and life-threatening outcomes. Our case describes diphenhydramine toxicity manifesting with two rare but potentially

life-threatening complications, rhabdomyolysis, and QT prolongation. Laboratory testing for diphenhydramine levels are not widely available. We recommend a high degree of suspicion for these complications when evaluating patients with diphenhydramine overdose, to adequately manage and prevent untoward outcomes.

Massively elevated creatine kinase levels in antihistamine-induced rhabdomyolysis

Rhabdomyolysis is the destruction of skeletal muscle tissue with release of intracellular components into the circulation. Elevation of creatine kinase levels in serum is indicative of muscle damage and is associated with acute kidney injury. Antihistamines are a rare cause of nontraumatic rhabdomyolysis. Herein we describe a case of intentional ingestion of diphenhydramine resulting in rhabdomyolysis with subsequent elevation in creatine kinase levels exceeding 2 million IU/L. Aggressive intravenous volume expansion rapidly lowered creatine kinase levels and improved renal function.

Extracorporeal Cardiopulmonary Resuscitation After Diphenhydramine Ingestion

INTRODUCTION

Diphenhydramine is a widely used first-generation histamine (H₁) antagonist that can be obtained without prescription in many countries. Massive ingestions can result in severe toxicity and even death. We describe a case of diphenhydramine overdose leading to cardiac arrest, cardiopulmonary resuscitation (CPR), and extracorporeal membrane oxygenation (ECMO) cannulation for refractory ventricular fibrillation, a process we refer to as extracorporeal cardiopulmonary resuscitation (ECPR).

CASE REPORT

Responding to a call for altered mental status, emergency medical service (EMS) personnel found an unconscious and seizing 17-year-old male. He had reportedly developed generalized tonic-clonic seizures and dysrhythmias after ingesting approximately 800 25-mg diphenhydramine tablets. He was transferred to our pediatric intensive care unit (PICU) after stabilization at a local emergency center. After approximately 7 hours of clinical stability and normalization of cardiac rhythm, electrolytes, and acidosis, he developed renewed seizure activity and accelerated ventricular rhythm leading to hemodynamic collapse and cardiac arrest. He was cannulated for veno-arterial extracorporeal membrane oxygenation (VAECMO) with CPR in progress. A pharmacobezoar located in his stomach was presumed to be the cause of his biphasic clinical deterioration. After 5 days, the patient was successfully weaned from ECMO support. Ten days later, his convalescence continued in the step-down unit and was discharged with good functional outcome.

DISCUSSION

Significant ingestion of anticholinergic substances is often fatal. This case describes a favorable outcome after ECPR and aggressive supportive management following a large intentional overdose of diphenhydramine.

Biodistribution of diphenhydramine in reproductive organs in an overdose case

Motion sickness medications such as Travelmin^® prescribed in Japan include diphenhydramine (DPH), dyphylline, diphenidol, and/or caffeine. Herein, we report a patient who died due to rhabdomyolysis after ingesting a DPH containing motion sickness medication. A Japanese male in his 30 s reported missing after going out for a drive early in the morning was found dead in his car in the evening of the same day. An autopsy showed moderate edema, congestion, and several petechiae in both lungs. The brain was congested and edematous with no atherosclerosis of cerebral arteries. The prostate and both testes were slightly edematous. Gastric contents included approximately 15 mL of dark-brown fluid without tablets or food residue. Toxicological examination showed that blood DPH levels in all tissues were between 4.90 and 7.27 μg/mL, which represented toxic to lethal levels. DPH (μg/mL) levels were approximately 3-9 times higher in the prostate (73.42) and testes (left, 28.23; right, 30.09) than those in all regions of the brain (range 7.75-12.33). Blood dyphylline, diphenidol and caffeine levels in reproductive organs reached high, but not toxic levels. In conclusion, DPH, dyphylline, diphenidol, and caffeine levels were higher in reproductive organs such as the prostate and testes than in the central nervous system and heart. As we determined in this case, motion sickness medications might accumulate in reproductive organs. Thus, further examination of tissue biodistribution of DPH, dyphylline, diphenidol, and caffeine is necessary to assess their potential long-term effects in these sites.

A single dose of histamine-receptor antagonists before downhill running alters markers of muscle damage and delayed-onset muscle soreness

Histamine contributes to elevations in skeletal muscle blood flow following exercise, which raises the possibility that histamine is an important mediator of the inflammatory response to exercise. We examined the influence of antihistamines on postexercise blood flow, inflammation, muscle damage, and delayed-onset muscle soreness (DOMS) in a model of moderate exercise-induced muscle damage. Subjects consumed either a combination of fexofenadine and ranitidine (blockade, n = 12) or nothing (control, n = 12) before 45 min of downhill running (-10% grade). Blood flow to the leg was measured before and throughout 120 min of exercise recovery. Markers of inflammation, muscle damage, and DOMS were obtained before and at 0, 6, 12, 24, 48, and 72 h postexercise. At 60 min postexercise, blood flow was reduced ~29% with blockade compared with control (P < 0.05). Markers of inflammation were elevated after exercise (TNF-ɑ, IL-6), but did not differ between control and blockade. Creatine kinase concentrations peaked 12 h after exercise, and the overall response was greater with blockade (18.3 ± 3.2 kU·l^-1·h^-1) compared with control (11.6 ± 2.0 kU·l^-1·h^-1; P < 0.05). Reductions in muscle strength in control (-19.3 ± 4.3% at 24 h) were greater than blockade (-7.8 ± 4.8%; P < 0.05) and corresponded with greater perceptions of pain/discomfort in control compared with blockade. In conclusion, histamine-receptor blockade reduced postexercise blood flow, had no effect on the pattern of inflammatory markers, increased serum creatine kinase concentrations, attenuated muscle strength loss, and reduced pain perception following muscle-damaging exercise.NEW & NOTEWORTHY Histamine appears to be intimately involved with skeletal muscle during and following exercise. Blocking histamine's actions during muscle-damaging exercise, via common over-the-counter antihistamines, resulted in increased serum creatine kinase, an indirect marker of muscle damage. Paradoxically, blocking histamine's actions attenuated muscle strength loss and reduced perceptions of muscle pain for 72 h following muscle-damaging exercise. These results indicate that exercise-induced histamine release may have a broad impact on protecting muscle from exercise-induced damage.

Diphenhydramine overdose with intraventricular conduction delay treated with hypertonic sodium bicarbonate and i.v. lipid emulsion

Diphenhydramine toxicity commonly manifests with antimuscarinic features, including dry mucous membranes, tachycardia, urinary retention, mydriasis, tachycardia, and encephalopathy. Severe toxicity can include seizures and intraventricular conduction delay. We present here a case of a 23-year-old male presenting with recurrent seizures, hypotension and wide complex tachycardia who had worsening toxicity despite treatment with sodium bicarbonate. The patient was ultimately treated with intravenous lipid emulsion therapy that was temporally associated with improvement in the QRS duration. We also review the current literature that supports lipid use in refractory diphenhydramine toxicity.

Iatrogenic neurology

Iatrogenic disease is one of the most frequent causes of hospital admissions and constitutes a growing public health problem. The most common type of iatrogenic neurologic disease is pharmacologic, and the central and peripheral nervous systems are particularly vulnerable. Despite this, iatrogenic disease is generally overlooked as a differential diagnosis among neurologic patients. The clinical picture of pharmacologically mediated iatrogenic neurologic disease can range from mild to fatal. Common and uncommon forms of drug toxicity are comprehensively addressed in this chapter. While the majority of neurologic adverse effects are listed and referenced in the tables, the most relevant issues are further discussed in the text.

Acute renal failure caused by pheniramine maleate induced rhabdomyolysis: an unusual case

Antihistamines are easily available over-the-counter medications, which are frequently involved in overdoses. The usual course is accompanied by the anticholinergic effects of these agents. We report a case of a suicide attempt in a young male, where ingestion of antihistamine pheniramine maleate was complicated by nontraumatic rhabdomyolysis and oliguric acute renal failure. Rhabdomyolysis and acute renal failure is a rarely reported but potentially serious complication among patients who present to the emergency after intentional overdoses making recognition and prompt intervention essential. We also describe the potential mechanism of muscle injury in antihistamine overdose.

Fatal diphenhydramine poisoning with increased vascular permeability including late pulmonary congestion refractory to percutaneous cardiovascular support

BACKGROUND

Fatal adult cases of acute diphenhydramine poisoning are extremely rare.

CASE REPORT

Transiently awakened by a roommate, a 39-year-old man admitted to massive ingestion of an over-the-counter drug containing diphenhydramine salicylate. On admission the patient was semicomatose and developed circulatory collapse with severe dehydration and metabolic acidosis, followed by status epilepticus. Despite extensive life support measures including percutaneous cardiopulmonary support, vascular permeability progressively increased, with pulmonary congestion as well as peripheral vasodilation evident as rubedo. The patient died without improvement of cardiac function. Subsequent diphenhydramine assays in serum specimens obtained at the time of delayed congestive symptoms indicated decreases in drug concentration to a sublethal amount.

DISCUSSION

We suspect that metabolites of diphenhydramine with histamine-agonist actions contributed to the development of fatal delayed symptoms.

Rhabdomyolysis: a review of clinical presentation, etiology, diagnosis, and management

Rhabdomyolysis is a condition that results from many underlying etiologies and can present in a myriad of ways to the emergency physician. However, some clinical and laboratory features are almost always present and, if noted, can help in making the diagnosis. This review article will focus on the presenting symptoms, the various etiologies, the underlying mechanisms, and the current management of pediatric rhabdomyolysis.

Diphenhydramine and dimenhydrinate poisoning: an evidence-based consensus guideline for out-of-hospital management

In 2003, there were 28,092 human exposures to diphenhydramine reported to poison centers in the US. A related drug, dimenhydrinate, is a less frequent cause of poisonings. Between January 2000 and June 2004, there were 2,534 reported dimenhydrinate ingestions in children less than 6 years of age. An evidence-based expert consensus process was used to create this guideline. Relevant articles were abstracted by a trained physician researcher. The first draft was created by the primary author. The entire panel discussed and refined the guideline before distribution to secondary reviewers for comment. The panel then made changes based on the secondary review comments. The objective of this guideline is to assist poison center personnel in the appropriate out-of-hospital triage and initial management of patients with a suspected ingestion of diphenhydramine or dimenhydrinate, or a dermal exposure to diphenhydramine. This guideline is based on an assessment of current scientific and clinical information. The expert consensus panel recognizes that specific patient care decisions may be at variance with this guideline and are the prerogative of the patient and the health professionals providing care, considering all of the circumstances involved. This guideline does not substitute for clinical judgment. The panel's recommendations for dermal or oral exposures to diphenhydramine or oral exposures to dimenhydrinate follow. The grade of recommendation is in parentheses: 1) All patients with suicidal intent, intentional abuse, or in cases in which a malicious intent is suspected (e.g., child abuse or neglect) should be referred to an emergency department (Grade D). 2) In patients without evidence of self-harm, abuse, or malicious intent, poison center personnel should elicit additional information including the time of the ingestion or dermal exposure, determination of the precise dose ingested, and the presence of co-ingestants (Grade D). 3) Patients experiencing any changes in behavior other than mild drowsiness or mild stimulation should be referred to an emergency department. Examples of moderate to severe symptoms that warrant referral include agitation, staring spells, inconsolable crying, hallucinations, abnormal muscle movements, loss of consciousness, seizures, or respiratory depression (Grade D). 4) For patients referred to the emergency department, transportation via ambulance should be considered based on several factors including the condition of the patient and the length of time it will take the patient to arrive at the emergency department (Grade D). 5) If the patient has no symptoms, and more than 4 hours have elapsed between the time of diphenhydramine ingestion and the call to the poison center, referral to an emergency department is not recommended. For dermal exposures to diphenhydramine, if the patient has no symptoms and it has been more than 8 hours since the diphenhydramine was thoroughly removed from the skin, referral to an emergency department is not recommended (Grade D). 6) Patients with acute ingestions of less than a toxic dose of diphenhydramine, or chronic exposures to diphenhydramine and no or mild symptoms, can be observed at home with instructions to call the poison center back if symptoms develop or worsen. The poison center should consider making a follow-up call at approximately 4 hours after ingestion (Grade D). 7) Children less than 6 years of age who ingest at least 7.5 mg/kg of diphenhydramine should be referred to an emergency department (Grade D). 8) Patients 6 years of age and older who ingest at least 7.5 mg/kg or 300 mg of diphenhydramine (whichever is less), should be referred to an emergency department (Grade D). 9) If the patient has no symptoms, and more than 6 hours have elapsed between the time of dimenhydrinate ingestion and the call to the poison center, referral to an emergency department is not recommended (Grade D). 10) Patients with acute ingestions of less than a toxic dose of dimenhydrinate, or chronic exposures to dimenhydrinate and no or mild symptoms, can be observed at home with instructions to call the poison center back if symptoms develop or worsen. The poison center should consider making a follow-up call at approximately 6 hours after ingestion (Grade D). 11) Children less than 6 years of age ingesting at least 7.5 mg/kg of dimenhydrinate should be referred to an emergency department (Grade D). 12) Patients 6 years of age and older ingesting at least 7.5 mg/kg or 300 mg of dimenhydrinate (whichever is less), should be referred to an emergency department for evaluation (Grade D). 13) Following oral exposures of diphenhydramine or dimenhydrinate, do not induce emesis. Because of the potential for diphenhydramine or dimenhydrinate to cause loss of consciousness or seizures, activated charcoal should not be administered en route to an emergency department (Grade D). 14) For chronic dermal exposures of diphenhydramine, skin decontamination (with water or soap and water) should be attempted prior to transporting a patient to an emergency department unless moderate to severe symptoms are already present. In this circumstance, transportation should not be delayed, and EMS personnel should attempt skin decontamination en route to the emergency department (Grade D). 15) Intravenous sodium bicarbonate may be administered by EMS personnel if QRS widening (QRS >0.10 msec) is present and if authorized by EMS medical direction (Grade D). 16) Physostigmine should be reserved for administration in a hospital (Grade D). 17) Benzodiazepines may be administered by EMS personnel if agitation or seizures are present, and if authorized by EMS medical direction (Grade D).

Effect of dextromethorphan, diphenhydramine, and placebo on nocturnal cough and sleep quality for coughing children and their parents

OBJECTIVES

To determine whether the commonly used over-the-counter medications dextromethorphan and diphenhydramine are superior to placebo for the treatment of nocturnal cough and sleep difficulty associated with upper respiratory infections and to determine whether parents have improved sleep quality when their children receive the medications when compared with placebo.

METHODS

Parents of 100 children with upper respiratory infections were questioned to assess the frequency, severity, and bothersome nature of the nocturnal cough. Their answers were recorded on 2 consecutive days, initially on the day of presentation, when no medication had been given the previous evening, and then again on the subsequent day, when either medication or placebo was given before bedtime. Sleep quality for both the child and the parent were also assessed for both nights.

RESULTS

For the entire cohort, all outcomes were significantly improved on the second night of the study when either medication or placebo was given. However, neither diphenhydramine nor dextromethorphan produced a superior benefit when compared with placebo for any of the outcomes studied. Insomnia was reported more frequently in those who were given dextromethorphan, and drowsiness was reported more commonly in those who were given diphenhydramine.

CONCLUSIONS

Diphenhydramine and dextromethorphan are not superior to placebo in providing nocturnal symptom relief for children with cough and sleep difficulty as a result of an upper respiratory infection. Furthermore, the medications given to children do not result in improved quality of sleep for their parents when compared with placebo. Each clinician should consider these findings, the potential for adverse effects, and the individual and cumulative costs of the drugs before recommending them to families.

Drug-induced rhabdomyolysis

PURPOSE OF REVIEW

Drug-induced rhabdomyolysis is a common syndrome that is complex and potentially life threatening. This article reviews the pathophysiology, clinical presentations, and common compounds that cause drug-induced rhabdomyolysis.

RECENT FINDINGS

The list of drugs and inciting agents that cause rhabdomyolysis is quite extensive. Rhabdomyolysis is defined as skeletal muscle injury that leads to the lysis of muscle cells and the leakage of myocyte contents into the extracellular compartments. The presenting clinical features are myalgias, myoglobinuria, and an elevated serum creatine kinase. There have been several case reports in the literature involving some common pediatric drugs that are associated with rhabdomyolysis. Diphenhydramine, Ecstasy, and baclofen have recently been implicated as the etiology of drug-induced rhabdomyolysis in several pediatric patients. Alkalinization of the urine is a controversial treatment of drug-induced rhabdomyolysis and has proven to be beneficial in some patients.

SUMMARY

A high index of suspicion, early recognition, and adequate treatment will result in an excellent prognosis of drug-induced rhabdomyolysis.

Antihistamine-induced Rhabdomyolysis

Antihistamines, which are readily available over the counter in sleeping aids, are commonly found in intentional overdoses. We report three new cases of severe rhabdomyolysis related to ingestion of these agents. This is a rarely reported but potentially overlooked complication among patients who present to the emergency center after intentional overdoses. We also describe the potential mechanism of muscle injury in antihistamine overdoses and comment on the potential for cross-reactivity of antihistamines with the urine screen for phencyclidine.

Rhabdomyolysis and acute renal failure following an ethanol and diphenhydramine overdose

OBJECTIVE

To report a case of nontraumatic rhabdomyolysis complicated by oliguric, acute renal failure following an intentional overdose of ethanol and diphenhydramine.

CASE SUMMARY

A 21-year-old white man was admitted through the emergency department following an intentional overdose of ethanol and diphenhydramine. The patient subsequently developed acute renal failure, and a diagnosis of nontraumatic rhabdomyolysis was made. With the absence of other common causes in this case, the rhabdomyolysis was believed to be due to the combined ethanol and diphenhydramine overdose.

DISCUSSION

Rhabdomyolysis is a severe and life-threatening syndrome caused by various insults to skeletal muscle, including drug-induced injury. Early detection and institution of effective treatments are essential to minimizing the complications of this syndrome. A delay in establishing the diagnosis in this case likely contributed to the severity of the renal failure.

CONCLUSIONS

Nontraumatic rhabdomyolysis is an uncommon adverse outcome of drug and toxin ingestion. Due to the potential severity of the complications of this syndrome and the importance of early recognition and treatment to prevent renal failure, clinicians should have a high index of suspicion for rhabdomyolysis following overdoses that involve alcohol or antihistamines.

Myoglobinuria

Myoglobinuria refers to an abnormal pathologic state in which an excessive amount of myoglobin is found in the urine, imparting a cola-like hue, usually in association with myonecrosis and a clinical picture of weakness, myalgias, and edema. Myoglobinuria is produced by multiple causes: any condition that accelerates the use or interferes with the availability of oxygen or energy substrates to muscle cells can result in myoglobinuria, as can events that produce direct muscle injury, either mechanical or chemical. Acute renal failure is the most serious complication, which can be prevented by prompt, aggressive treatment. In patients surviving acute attacks, recovery of muscle and renal function is usually complete.