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

Antidotes in Clinical Toxicology-Critical Review

Poisoning and overdose are very important aspects in medicine and toxicology. Chemical weapons pose a threat to civilians, and emergency medicine principles must be followed when dealing with patients who have been poisoned or overdosed. Antidotes have been used for centuries and modern research has led to the development of new antidotes that can accelerate the elimination of toxins from the body. Although some antidotes have become less relevant due to modern intensive care techniques, they can still save lives or reduce the severity of toxicity. The availability of antidotes is crucial, especially in developing countries where intensive care facilities may be limited. This article aims to provide information on specific antidotes, their recommended uses, and potential risks and new uses. In the case of poisoning, supportive therapies are most often used; however, in many cases, the administration of an appropriate antidote saves the patient's life. In this review, we reviewed the literature on selected antidotes used in the treatment of poisonings. We also characterised the antidotes (bio)chemically. We described the cases in which they are used together with the dosage recommendations. We also analysed the mechanisms of action. In addition, we described alternative methods of using a given substance as a drug, an example of which is N-acetylcysteine, which can be used in the treatment of COVID-19. This article was written as part of the implementation of the project of the Polish Ministry of Education and Science, "Toxicovigilance, poisoning prevention, and first aid in poisoning with xenobiotics of current clinical importance in Poland", grant number SKN/SP/570184/2023.

Potentially inappropriate prescribing in hospitalised children: a retrospective, cross-sectional study at a tertiary children's hospital in China

INTRODUCTION

For improving and optimising drug use in children, we previously developed a tool (including a series of criteria for identifying potentially inappropriate prescribing in children) by literature review and the two-round Delphi technique to prevent inappropriate medication prescriptions at the prescribing stage.

OBJECTIVE

To assess the prevalence of potentially inappropriate prescription (PIP) among hospitalised children and explore risk factors associated with PIP.

DESIGN

A retrospective cross-sectional study.

SETTING

A tertiary children's hospital in China.

PARTICIPANTS

Hospitalised children with complete medical records who received drug treatment and discharged from 1 January to 31 December 2021.

OUTCOME MEASURES

We evaluated the medication prescriptions by using a series of previously developed criteria for detecting the prevalence of PIP in hospitalised children and used logistic regression to explore the risk factors (including sex, age, number of drugs, number of comorbidities, days of hospitalisation and admission departments) for PIP in children.

RESULTS

A total of 87 555 medication prescriptions for 16 995 hospitalised children were analysed, and 19 722 PIPs were detected. The prevalence of PIP was 22.53%, and 36.92% of the children had at least one PIP during hospitalisation. The department with the highest prevalence of PIP was the surgical department (OR 9.413; 95% CI 5.521 to 16.046), followed by the paediatric intensive care unit (PICU; OR 8.206; 95% CI 6.643 to 10.137). 'Inhaled corticosteroids for children with respiratory infections but without chronic respiratory diseases' was the most frequent PIP. Logistic regression results showed that PIP was more likely to occur in male patients (OR 1.128, 95% CI 1.059 to 1.202) and younger patients (<2 years old; OR 1.974; 95% CI 1.739 to 2.241), and in those with more comorbidities (≥11 types; OR 4.181; 95% CI 3.671 to 4.761), concomitant drugs (≥11 types; OR 22.250; 95% CI 14.468 to 34.223) or longer hospital stay (≥30 days; OR 8.130; 95% CI 6.727 to 9.827).

CONCLUSIONS

Medications for long-term hospitalised young children with multiple comorbidities should be minimised and optimised, to avoid PIP, reduce adverse drug reactions and ensure children's medication safety. The surgery department and PICU had a high prevalence of PIP in the studied hospital and should be the focus of supervision and management in routine prescription review.

Urinary retention triggered by dimenhydrinate: A case report

The antihistamine dimenhydrinate as the trigger of acute urinary retention has not been reported. A 35-year-old female with a long-term history of depression treated with sertraline (150 mg/d) since years developed acute urinary retention after having received 100 mg dimenhydrinate intravenously for excessive, postural vertigo. Urinary retention required placement of a disposable catheter, which halted 1.6 liter of urine. Since urinary retention persisted, she received a permanent catheter, which initially halted another 1.2 liter of urine. Urinary retention resolved spontaneously within 48 hours, and the patient was discharged with her previous medication. This case shows that intravenous dimenhydrinate can trigger the development of acute urinary retention in patients under long-term treatment with sertraline, which is why it should be given with caution in this group of patients.

Case Report: De Novo and Persistent Psychosis After Withdrawal From Chronic Opioid Therapy

Psychiatric illness is associated with both chronic pain syndromes and opioid use disorder, further complicating how we care for patients with psychiatric issues. We report a unique case of a de novo and persistent psychotic disorder after complicated opioid withdrawal in a patient without any psychiatric history. The patient developed persistent auditory hallucinations after discontinuation of chronic opioid therapy that responded only to atypical antipsychotic (olanzapine) treatment. This case illustrates the neuropsychiatric effects of chronic opioid exposure, as well as layered clinical management dimensions related to opioid detoxification and psychosis treatment. Long-term opioid therapy may have lasting neuropsychiatric effects, including playing a role in the development and/or expression of psychotic disorders. Here we review the limited literature on the effects of opioids on psychosis. This complex case also demonstrates a clinical approach for effectively co-managing psychiatric symptoms in the context of chronic pain and chronic opioid therapy.

Do Pediatric Emergency Physicians Comply With Guideline Recommendations in Management of Patients With Acute Urticaria?

OBJECTIVES

To determine the level of knowledge and practical preferences of pediatricians regarding acute urticaria (AU) management and to assess the effects of training provided in accordance with the current urticaria guideline recommendations on pediatricians who work in the pediatric emergency department (PED).

METHODS

A theoretical training was provided to pediatricians regarding the diagnosis and treatment of AU in line with current urticaria guideline recommendations. Before the training, pediatricians completed a 10-item questionnaire. This prospective study assesses their treatment approaches in patients admitted to PED because of AU during the 6-month period before and the 1-year period after training.

RESULTS

Four hundred seventeen children in the pretraining and 1085 children in the posttraining periods were treated for AU in PED. Forty-eight pediatricians participated in the training. According to their questionnaire responses, 35% of them used only H1 antihistamine (AH) treatment, 50% used second-generation H1 AH (2nd-GAH) as AHs, 75% preferred the oral route of administration, and 85.4% did not administer systemic corticosteroid (sCS) to all patients. Comparing the practice approaches of the pediatricians in the pretraining and posttraining periods, first-generation H1 antihistamine (1st-GAH) preference rate decreased from 68.4% to 30.3% and the sCS preference rate decreased from 58.5% to 25.7%, while the 2nd-GAH preference rate increased from 31.7% to 69.7% (P < 0.001 for all). No treatments were prescribed for 10.8% of patients before the training and 3% after the training during discharge at home (P < 0.05). Comparing the home treatment choices of the pediatricians in the pretraining and posttraining periods, 1st-GAH preference rate decreased from 11.5% to 5%, while the 2nd-GAH preference rate increased from 78.7% to 91.5% (for both parameters, P < 0.001).

CONCLUSIONS

Practical treatment preferences of pediatricians in the treatment of children with AU differ considerably from both current guideline recommendations and their own theoretical knowledge, and training can enhance pediatricians' compliance with current guideline recommendations.

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.

Towards definitive management of allergic rhinitis: best use of new and established therapies

BACKGROUND

Allergic rhinitis (AR) is an inflammatory disease of the nasal mucosa impacting up to 25% of Canadians. The standard of care for AR includes a treatment plan that takes into account patient preferences, the severity of the disease, and most essentially involves a shared decision-making process between patient and provider.

BODY

Since their introduction in the 1940s, antihistamines (AHs) have been the most utilized class of medications for the treatment of AR. First-generation AHs are associated with adverse central nervous system (CNS) and anticholinergic side effects. On the market in the 1980s, newer generation AHs have improved safety and efficacy. Compared to antihistamines, intranasal corticosteroids (INCS) have significantly greater efficacy but longer onset of action. Intranasal AH and INCS combinations offer a single medication option that offers broader disease coverage and faster symptom control. However, cost and twice-per-day dosing remain a major limitation. Allergen immunotherapy (AIT) is the only disease-modifying option and can be provided through subcutaneous (SCIT) or sublingual (SLIT) routes. While SCIT has been the definitive management option for many years, SLIT tablets (SLIT-T) have also been proven to be safe and efficacious.

CONCLUSION

There is a range of available treatment options for AR that reflect the varying disease length and severity. For mild to moderate AR, newer generation AHs should be the first-line treatment, while INCS are mainstay treatments for moderate to severe AR. In patients who do not respond to INCS, a combination of intranasal AH/INCS (AZE/FP) should be considered, assuming that cost is not a limiting factor. While SCIT remains the option with the most available allergens that can be targeted, it has the potential for severe systemic adverse effects and requires weekly visits for administration during the first 4 to 6 months. SLIT-T is a newer approach that provides the ease of being self-administered and presents a reduced risk for systemic reactions. In any case, standard care for AR includes a treatment plan that takes into account disease severity and patient preferences.

CSACI position statement: Newer generation H1-antihistamines are safer than first-generation H1-antihistamines and should be the first-line antihistamines for the treatment of allergic rhinitis and urticaria

Oral H₁-antihistamines (AHs) are the most commonly used therapy to treat allergic rhinitis and chronic urticaria. Older, first-generation AHs (e.g. diphenhydramine, hydroxyzine) have significant and common side effects including sedation, impairment with decreased cognitive function, poor sleep quality, dry mouth, dizziness, and orthostatic hypotension. These drugs have also been found to result in death from accidents, intentional or unintentional overdoses, and sudden cardiac death. The unfavourable risk–benefit profile of first-generation AHs led to the development of newer, less-sedating second- and third-generation AHs, which first became available in Canada in the 1980s. High-quality trials have proven that newer generation AHs are superior in safety compared to older first-generation AHs. On average, they have improved potency and efficacy. Second- and third-generation AHs are the recommended first-line treatment for mild allergic rhinitis and acute and chronic urticaria. Despite this evidence, older first-generation AHs continue to be over-utilized because of their over-the-counter (OTC) status and long history of use. The Canadian Society of Allergy Clinical Immunology (CSACI) recommends that newer generation AHs should be preferred over first-generation AHs for the treatment of allergic rhino-conjunctivitis and urticaria. To promote this recommendation, education of health professionals and the public is necessary. Further, given the dangers of older first-generation AHs, we believe they should be used only as a last resort with eventual consideration given to having them only available behind the counter in pharmacies.

Poison-related visits in a pediatric emergency department: A retrospective analysis of patients who bypass poison control centers

INTRODUCTION

Poison control centers (PCC) are an effective means to prevent unnecessary emergency department (ED) visits associated with poisoning exposures. However, not all patients with poison exposures utilize the PCC. The purpose of this study was to identify unintentional pediatric poisoning exposures presenting to a large US children's hospital that could have been managed onsite (i.e., at home) if consultation with a PCC had occurred prior to the ED visit.

METHODS

Using ED encounters from a tertiary children's hospital, unintentional pharmaceutical, chemical, or fume exposures occurring between October 1, 2014 and September 30, 2015 were identified from ICD-9-CM billing codes. Two specialists in poison information reviewed the medical records of the identified patients who had no contact with the PCC and determined whether these encounters were preventable through PCC triage. Descriptive statistics examined the differences between the encounters. Data were analyzed in R v3.2.4 (Vienna, Austria) and SAS v9.4 (SAS Institute, Cary, NC).

RESULTS

In the total study population (n = 231), 98 (42.4%) were PCC triaged and 133 (57.6%) were caregiver self-referred to the ED. For those who self-referred, 62 (46.6%) patients would have been recommended to be managed onsite instead of presenting at the ED for medical care. Analgesics and household cleaning products were the most common pharmaceutical and chemical exposures, respectively.

CONCLUSIONS

Nearly half of ED visits for pediatric patients with unintentional poisoning exposures could have been avoided by contacting a PCC. Educational and self-efficacy-based interventions are needed to expand the public's use of PCC services.

Adverse events associated with diphenhydramine in children, 2008-2015

Introduction: Diphenhydramine (DPH) exposures in children may be the result of accidental unsupervised ingestions, caregiver error, and intentional misuse of DPH-containing cough and cold medications (CCM). We sought to understand the nature of pediatric ingestions of DPH, particularly the toxicity and outcome of a single product, single ingredient DPH (DPH-only) exposures, in order to derive ingredient-specific information about the clinical effects and course of such cases.Methods: As part of a U.S. multi-year safety surveillance program to assess the safety of over-the-counter (OTC) medications used in cough and cold preparations in children <12 years of age, an expert panel reviewed cases involving symptomatic adverse events potentially related to oral exposures to these medications. After individual review, the cases were categorized by causal relationship of the reported ingredients to the adverse event, exposure intent (therapeutic, non-therapeutic, unknown intent), and dose (therapeutic, supratherapeutic, or unknown). Following panel review, any disagreement on classification was discussed until a consensus was reached. The data were then analyzed with respect to descriptive findings.Results: The panel reviewed 6618 eligible cases and determined 2802 were at least potentially related to oral exposure to DPH. Of these, 2028 were DPH-only cases (39.1% of all cases judged at least potentially related to a cough and cold medication). The majority (79.5%) of DPH-only cases occurred in children 2 to <4 years of age and involved accidental unsupervised ingestions (74.7%). Liquid pediatric formulations were the most common (51.7%) products reported followed by solid pediatric formulations (24.0%). The most common adverse events were tachycardia (53.4%), hallucinations (46.5%), somnolence (34.7%), agitation (33.9%), and mydriasis (26.3%). Seizures occurred in only 5.5% of cases. Five (0.2%) deaths were reported; in the death cases, the DPH dose was judged supratherapeutic in one and unknown in the other four. Child abuse was reported in four of the five death cases and three of the five deaths were homicides.Conclusions: Exposures to DPH-only products were the most common type of exposure detected in our study of adverse events associated with CCM in children. The majority of the DPH-only cases were the result of accidental unsupervised ingestions. Most adverse events were relatively mild self-limited anticholinergic effects and few deaths occurred. Deaths involving DPH were often associated with child abuse or homicide. Interventions targeting the prevention of accidental unsupervised are likely to be impactful in preventing morbidity associated with DPH-only exposure.

Ingestion of Over-the-Counter Liquid Medications: Emergency Department Visits by Children Aged Less Than 6 Years, 2012-2015

INTRODUCTION

Unintentional medication ingestions by young children lead to nearly 60,000 emergency department visits annually; 15% involve oral liquid medications. Safety packaging improvements have been shown to limit liquid medication ingestions. Estimated rates of emergency department visits for pediatric ingestions by product were calculated to help target interventions.

METHODS

Frequencies and rates of emergency department visits for unintentional pediatric ingestions were estimated using adverse event data from the National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance project and retail sales/pharmacy dispensing data from Information Resources, Inc. and QuintilesIMS (collected 2012-2015; analyzed 2017). Rates of emergency department visits for ingestions of over-the-counter liquid medications were compared with those for prescription solid medications.

RESULTS

From the results of 568 cases, an estimated 6,427 emergency department visits (95% CI=4,907, 7,948) were made annually after a child aged <6 years accessed one of the four most commonly implicated over-the-counter liquid medications without caregiver oversight. Nearly two thirds (63.8%) of these visits were made by children aged ≤2 years and 9.0% resulted in hospitalization. Acetaminophen was the most commonly implicated over-the-counter liquid medication (2,515 estimated emergency department visits annually). Rates of emergency department visits for liquid diphenhydramine and acetaminophen ingestions (8.1 and 7.4 emergency department visits per 100,000 bottles sold) were higher than rates for other common over-the-counter liquids and comparable to high-rate prescription solid medications (clonidine and buprenorphine/naloxone: 11.1 and 10.5 emergency department visits per 100,000 dispensed prescriptions, respectively).

CONCLUSIONS

Product-specific rates of emergency department visits for unintentional ingestions can help prioritize preventive interventions, such as enhancing safety packaging with flow restrictors.

Cardiac arrest caused by diphenhydramine overdose

Case

A 45‐year‐old man presented to our emergency department with disturbance of consciousness; he had mentioned to his family earlier about a drug overdose. When first responders arrived, he suffered cardiac arrest. Cardiac arrest due to drug overdose was diagnosed.The patient was supported with venoarterial extracorporeal membrane oxygenation. Arterial blood gas showed mixed acidosis, and electrocardiogram showed junctional rhythm and complete right bundle branch block.

Outcome

The patient's blood pressure gradually decreased, and he died on the third day of hospitalization. After death, his serum diphenhydramine concentration at the time of arrival was found to be 18.7 μg/mL.

Conclusion

Although diphenhydramine is regarded as a safe medication, it shows dose‐dependent toxicity. High intake is associated with death; therefore, caution should be exercised in cases of drug overdose. Developing a procedure for rapid measurement in the emergency department should be a priority.

Eszopiclone ingestions reported to Texas poison control centers, 2005—2006

Eszopiclone is a nonbenzodiazepine hypnotic for the treatment of insomnia and classified as schedule IV controlled substance. Limited information exists on eszopiclone ingestions reported to poison control centers. The distribution of eszopiclone ingestions reported to Texas poison control centers during 2005—2006 was determined for various factors. In addition, triage guidelines for the management of such ingestions were drafted. Of 525 total eszopiclone ingestions, 259 involved coingestants. Of coingestant cases, 78.8% involved suspected attempted suicide and 90.7% were managed at a healthcare facility. Of 266 ingestions of eszopiclone alone, 40.2% were suspected attempted suicide and 62.0% were managed at a healthcare facility. A final medical outcome and dose ingested were known for 60 ingestions of eszopiclone alone. The mean dose was 28.3 mg (range 0.3—210 mg). Ingestions of eszopiclone alone of ≤6 and >6 mg differed with respect to the proportion involving suspected attempted suicide (0.0% versus 64.7%), final medical outcome of minor or moderate effect (38.5% versus 67.6%) and management at a healthcare facility (34.6% versus 91.2%). Using 6 mg as a threshold dose for referral to a healthcare facility, 78% of cases not already at/en route to a healthcare facility were managed according drafted triage guidelines. Human & Experimental Toxicology (2007) 26, 795— 800

webPOISONCONTROL: can poison control be automated?

BACKGROUND

A free webPOISONCONTROL app allows the public to determine the appropriate triage of poison ingestions without calling poison control. If accepted and safe, this alternative expands access to reliable poison control services to those who prefer the Internet over the telephone. This study assesses feasibility, safety, and user-acceptance of automated online triage of asymptomatic, nonsuicidal poison ingestion cases.

METHODS

The user provides substance name, amount, age, and weight in an automated online tool or downloadable app, and is given a specific triage recommendation to stay home, go to the emergency department, or call poison control for further guidance. Safety was determined by assessing outcomes of consecutive home-triaged cases with follow-up and by confirming the correct application of algorithms. Case completion times and user perceptions of speed and ease of use were measures of user-acceptance.

RESULTS

Of 9256 cases, 73.3% were triaged to home, 2.1% to an emergency department, and 24.5% directed to call poison control. Children younger than 6 years were involved in 75.2% of cases. Automated follow-up was done in 31.2% of home-triaged cases; 82.3% of these had no effect. No major or fatal outcomes were reported. More than 91% of survey respondents found the tool quick and easy to use. Median case completion time was 4.1 minutes.

CONCLUSION

webPOISONCONTROL augments traditional poison control services by providing automated, accurate online access to case-specific triage and first aid guidance for poison ingestions. It is safe, quick, and easy to use.

Novel use of dexmedetomidine for the treatment of anticholinergic toxidrome

INTRODUCTION

We report the case of an adolescent with anticholinergic toxidrome from diphenhydramine overdose, whose symptoms were treated with a novel application of dexmedetomidine.

CASE REPORT

A 13-year-old female developed an anticholinergic toxidrome after intentionally ingesting 9.5 mg/kg of diphenhydramine. Despite routine supportive therapies, to include appropriate doses of lorazepam, she continued to have significant agitation, psychosis, and hallucinations. A dexmedetomidine infusion was started to aid in the treatment of her agitation and psychosis with marked improvement of her symptoms.

DISCUSSION

Using dexmedetomidine for the treatment of anticholinergic toxidrome has not been previously described in the literature, but there are multiple reports of its use in alcohol withdrawal syndrome. We suggest that adding dexmedetomidine as an adjunctive agent in the therapy of anticholinergic toxidrome may relieve the symptoms of agitation, psychosis, tachycardia, and hypertension, without the attendant risk of respiratory depression associated with high doses of benzodiazepines.

Parkinson's disease: carbidopa, nausea, and dyskinesia

When l-dopa use began in the early 1960s for the treatment of Parkinson's disease, nausea and reversible dyskinesias were experienced as continuing side effects. Carbidopa or benserazide was added to l-dopa in 1975 solely to control nausea. Subsequent to the increasing use of carbidopa has been the recognition of irreversible dyskinesias, which have automatically been attributed to l-dopa. The research into the etiology of these phenomena has identified the causative agent of the irreversible dyskinesias as carbidopa, not l-dopa. The mechanism of action of the carbidopa and benserazide causes irreversible binding and inactivation of vitamin B6 throughout the body. The consequences of this action are enormous, interfering with over 300 enzyme and protein functions. This has the ability to induce previously undocumented profound antihistamine dyskinesias, which have been wrongly attributed to l-dopa and may be perceived as irreversible if proper corrective action is not taken.

Efficacy of flow restrictors in limiting access of liquid medications by young children

OBJECTIVE

To assess whether adding flow restrictors (FRs) to liquid medicine bottles can provide additional protection against unsupervised medication ingestions by young children, even when the child-resistant closure is not fully secured.

STUDY DESIGN

In April and May 2012, we conducted a block randomized trial with a convenience sample of 110 3- and 4-year-old children from 5 local preschools. Participants attempted to remove test liquid from an uncapped bottle with an FR and a control bottle without an FR (with either no cap or an incompletely closed cap).

RESULTS

All but 1 (96%; 25 of 26) of the open control bottles and 82% (68 of 83) of the incompletely closed control bottles were emptied within 2 minutes. Only 6% (7 of 110) of the bottles with FRs were emptied during the 10-minute testing period, none before 6 minutes. Overall, children removed less liquid from the bottles with FRs than from the open or incompletely closed control bottles without FRs (both P < .001). All children assigned open control bottles and 90% of those assigned incompletely closed control bottles removed ≥ 25 mL of liquid. In contrast, 11% of children removed ≥ 25 mL of liquid from uncapped bottles with FRs. Older children (aged 54-59 months) were more successful than younger children at removing ≥ 25 mL of liquid (P = .002) from bottles with FRs.

CONCLUSION

Our findings suggest that adding FRs to liquid medicine bottles limits the accessibility of their contents to young children and could complement the safety provided by current child-resistant packaging.

Restricting cough and cold medicines in children

AIMS

Based on concerns about safety and efficacy, international authorities have either advised against the use of cough and cold medication or considering such action. We aimed to systematically review the evidence for the effectiveness and safety of cough and cold medicines in children.

METHODS

We conducted a systematic review to identify studies relating to the use of products to treat symptoms of the common cold, influenza or allergic rhinitis, and relating to poisoning or toxicity from unintentional ingestion or overdose in children (<12 years). Medline, Embase and the Cochrane database were searched. No meta-analysis was undertaken because of the paucity of evidence, multiple medicines available, and the need to consider both effectiveness and safety.

RESULTS

Seventy two relevant studies or clinical reports were identified. There was little support for the effectiveness of these medicines for acute cough or the common cold in children. However, the majority of these medicines do not appear to be highly toxic in children and are not a major cause of severe effects following unintentional poisoning. The common use of these agents does not appear to be responsible for increased deaths in young children. Many cases of toxicity from cough and cold medications in young children are a result of therapeutic error. Particular medications, including diphenhydramine and codeine, appear to be associated with a high frequency of severe adverse effects and toxicity.

CONCLUSION

Restriction of cough and cold medicines in children is supported by currently available evidence.

Risk of first-generation H(1)-antihistamines: a GA(2)LEN position paper

BACKGROUND

First-generation H(1)-antihistamines obtained without prescription are the most frequent form of self-medication for allergic diseases, coughs and colds and insomnia even though they have potentially dangerous unwanted effects which are not recognized by the general public.

AIMS

To increase consumer protection by bringing to the attention of regulatory authorities, physicians and the general public the potential dangers of the indiscriminate use first-generation H(1)-antihistamines purchased over-the counter in the absence of appropriate medical supervision.

METHODS

A GA(2)LEN (Global Allergy and Asthma European Network) task force assessed the unwanted side-effects and potential dangers of first-generation H1-antihistamines by reviewing the literature (Medline and Embase) and performing a media audit of US coverage from 1996 to 2008 of accidents and fatal adverse events in which these drugs were implicated.

RESULTS

First-generation H(1)-antihistamines, all of which are sedating, are generally regarded as safe by laypersons and healthcare professionals because of their long-standing use. However, they reduce rapid eye movement (REM)-sleep, impair learning and reduce work efficiency. They are implicated in civil aviation, motor vehicle and boating accidents, deaths as a result of accidental or intentional overdosing in infants and young children and suicide in teenagers and adults. Some exhibit cardiotoxicity in overdose.

CONCLUSIONS

This review raises the issue of better consumer protection by recommending that older first-generation H(1)-antihistamines should no longer be available over-the-counter as prescription- free drugs for self-medication of allergic and other diseases now that newer second- generation nonsedating H(1)-antihistamines with superior risk/benefit ratios are widely available at competitive prices.

Dimenhydrinate in children with infectious gastroenteritis: a prospective, RCT

OBJECTIVE

Vomiting is a common symptom in children with infectious gastroenteritis. It contributes to fluid loss and is a limiting factor for oral rehydration therapy. Dimenhydrinate has traditionally been used for children with gastroenteritis in countries such as Canada and Germany. We investigated the efficacy and safety of dimenhydrinate in children with acute gastroenteritis.

METHODS

We performed a prospective, randomized, placebo-controlled, multicenter trial. We randomly assigned 243 children with presumed gastroenteritis and vomiting to rectal dimenhydrinate or placebo. Children with no or mild dehydration were included. All children received oral rehydration therapy. Primary outcome was defined as weight gain within 18 to 24 hours after randomization. Secondary outcomes were number of vomiting episodes, fluid intake, parents' assessment of well-being, number of diarrheal episodes, and admission rate to hospital. We recorded potential adverse effects.

RESULTS

Change of weight did not differ between children who received dimenhydrinate or placebo. The mean number of vomiting episodes between randomization and follow-up visit was 0.64 in the dimenhydrinate group and 1.36 in the placebo group. In total, 69.6% of the children in the dimenhydrinate group versus 47.4% in the placebo group were free of vomiting between randomization and the follow-up visit. Hospital admission rate, fluid intake, general well-being of the children, and potential adverse effects, including the number of diarrhea episodes, were similar in both groups.

CONCLUSIONS

Dimenhydrinate reduces the frequency of vomiting in children with mild dehydration; however, the overall benefit is low, because it does not improve oral rehydration and clinical outcome.

H1 antihistamines: current status and future directions

In this review, we compare and contrast the clinical pharmacology, efficacy, and safety of first-generation H1 antihistamines and second-generation H1 antihistamines. First-generation H1 antihistamines cross the blood-brain barrier, and in usual doses, they potentially cause sedation and impair cognitive function and psychomotor performance. These medications, some of which have been in use for more than 6 decades, have never been optimally investigated. Second-generation H1 antihistamines such as cetirizine, desloratadine, fexofenadine, levocetirizine, and loratadine cross the blood-brain barrier to a significantly smaller extent than their predecessors. The clinical pharmacology, efficacy, and safety of these medications have been extensively studied. They are therefore the H1 antihistamines of choice in the treatment of allergic rhinitis, allergic conjunctivitis, and urticaria. In the future, clinically advantageous H1 antihistamines developed with the aid of molecular techniques might be available.

Paradoxical excitation on diphenhydramine may be associated with being a CYP2D6 ultrarapid metabolizer: three case reports

Diphenhydramine is a widely used antihistaminic that is frequently included in over-the-counter medications. Due to its sedating properties, diphenhydramine is used in some hypnotic preparations. Occasionally, patients respond to diphenhydramine with paradoxical excitation. There are no studies on the prevalence of paradoxical excitation in healthy subjects. Diphenhydramine appears to cause mild inhibition of the cytochrome P450 (CYP) 2D6 enzyme. This can be interpreted as competitive inhibition, suggesting that diphenhydramine may be a CYP2D6 substrate. When subjects have at least three active copies of the CYP2D6 gene, they are called ultrarapid metabolizers (UMs) and present high metabolic capacity for CYP2D6 substrates. In the United States, CYP2D6 UMs may account for approximately 1% to 2% of the population. We describe three CYP2D6 UMs who reported paradoxical excitation on diphenhydramine. These cases suggest that in CYP2D6 UMs, diphenhydramine may be converted to a compound that causes excitation due to the abnormally high CYP2D6 activity. Therefore, such individuals may be at higher risk for excitation. Although these are only three anecdotal cases of paradoxical excitation from three CYP2D6 UMs, the reports illustrate the need for larger, more formal studies of diphenhydramine responses in CYP2D6 UMs and of diphenhydramine metabolism.

Dimenhydrinate effect on cerebral oxygen status and salivary chromogranin-A during cognitive tasks

To investigate the effects of dimenhydrinate on cerebral oxygen status (COS; cerebral oxygenated hemoglobin concentration changes) and salivary chromogranin-A (CgA) during a cognitive test battery, a double-blind, placebo-controlled, randomized, crossover protocol was used to examine the effect of 50 mg of dimenhydrinate or placebo in 12 subjects. This test battery includes tests of both reaction time and fundamental cognitive ability and was used in the assessment of pilots. Poor cognitive performance was observed in the subjects taking dimenhydrinate. We used two-channel near-infrared spectroscopy to investigate the effects of dimenhydrinate on the COS. With the one exception of shifting attention task in the left forehead, no significant difference was found between dimenhydrinate and placebo during the tasks of the test battery. Under placebo treatment, on the other hand, CgA levels were significantly elevated during cognitive testing when compared with baseline. However, CgA levels were not significantly elevated above baseline following dimenhydrinate. The present study is one of the first to demonstrate that the first-generation antihistamine drugs altered the responses of salivary CgA during cognitive tasks. The changes in salivary CgA secretion, as a result of dimenhydrinate administration, may serve as a sensitive biomarker of a psychological status such as a drug-induced sedation during the performance of a cognitive test battery. Further studies, however, are required to examine the usefulness of this sensitive biomarker in investigation of psychological agents during cognitive tasks.

Antihistamine mepyramine directly inhibits KCNQ/M channel and depolarizes rat superior cervical ganglion neurons

The first-generation antihistamines are widely prescribed medications that relieve allergic reactions and urticaria by blocking the peripheral histamine H(1) receptor. Overdose of these drugs often results in serious neuronal toxic effects, including seizures, convulsions and worsening of epileptic symptoms. The KCNQ/M K(+) channel plays a crucial role in controlling neuron excitability. Here, we demonstrate that mepyramine and diphenhydramine, two structurally related first-generation antihistamines, can act as potent KCNQ/M channel blockers. Extracellular application of these drugs quickly and reversibly reduced KCNQ2/Q3 currents heterologously expressed in HEK293 cells. The current inhibition was concentration and voltage dependent. The estimated IC(50) (12.5 and 48.1 microM, respectively) is within the range of drug concentrations detected in poisoned patients (30-300 microM). Both drugs shifted the I-V curve of KCNQ2/Q3 channel to more depolarized potentials and altered channel gating properties by prolonging activation and shortening deactivation kinetics. Mepyramine also inhibited the individual homomeric KCNQ1-4 and heteromeric KCNQ3/Q5 currents. Moreover, mepyramine inhibited KCNQ2/Q3 current in an outside-out patch excised from HEK293 cells and the inhibitory effect was neither observed when it was applied intracellularly nor affected by blocking phospholipase C (PLC) activity, indicating an extracellular and direct channel blocking mechanism. Finally, in cultured rat superior cervical ganglion (SCG) neurons, mepyramine reduced the M type K(+) current in a concentration-dependent manner and led to marked membrane potential depolarization. It is likely that these effects may be involved in the adverse neuroexcitatory effects observed in patients experiencing an overdose of antihistamines.

Safety of levocetirizine treatment in young atopic children: An 18-month study

There are more than 40 H(1)-antihistamines available worldwide. Most of these medications have never been optimally studied in prospective, randomized, double-masked, placebo-controlled trials in children. The aim was to perform a long-term study of levocetirizine safety in young atopic children. In the randomized, double-masked Early Prevention of Asthma in Atopic Children Study, 510 atopic children who were age 12-24 months at entry received either levocetirizine 0.125 mg/kg or placebo twice daily for 18 months. Safety was assessed by: reporting of adverse events, numbers of children discontinuing the study because of adverse events, height and body mass measurements, assessment of developmental milestones, and hematology and biochemistry tests. The population evaluated for safety consisted of 255 children given levocetirizine and 255 children given placebo. The treatment groups were similar demographically, and with regard to number of children with: one or more adverse events (levocetirizine, 96.9%; placebo, 95.7%); serious adverse events (levocetirizine, 12.2%; placebo, 14.5%); medication-attributed adverse events (levocetirizine, 5.1%; placebo, 6.3%); and adverse events that led to permanent discontinuation of study medication (levocetirizine, 2.0%; placebo, 1.2%). The most frequent adverse events related to: upper respiratory tract infections, transient gastroenteritis symptoms, or exacerbations of allergic diseases. There were no significant differences between the treatment groups in height, mass, attainment of developmental milestones, and hematology and biochemistry tests. The long-term safety of levocetirizine has been confirmed in young atopic children.